Salmonella

Vet Microbiol, 2002 Oct 2, 89(1), 53 - 60
The prevalence and PCR detection of Salmonella contamination in raw poultry; Whyte P et al.; Contaminated poultry meat has been identified as one of the principal foodborne sources of Salmonella . The development of rapid detection assays for Salmonella would enable official agencies and food industries to identify contaminated foodstuffs in a more timely manner . In addition, these diagnostic tools could allow more 'real time' decisions to be made regarding end product acceptability . In this study, a survey was carried out to determine the prevalence of Salmonella in raw broiler carcasses . A total of 198 neck skin samples were obtained from within 40 flocks at a commercial broiler slaughtering facility . The presence of Salmonella was assessed by traditional culture methods and by a Salmonella-specific polymerase chain reaction (PCR) test . Salmonella was recovered from 32 (16%) of all samples using traditional culture methods . In contrast, the PCR assay proved to be more sensitive and detected Salmonella DNA in 38 (19%) of the samples tested . The pathogen was detected in 45 (23%) of the 198 samples when culture and PCR results were combined . The sensitivity of the PCR test was also greater than culture when detecting Salmonella from within flocks (53% of flocks by PCR, 30% of flocks by culture) . The combination of both tests revealed that 55% of the flocks were contaminated with Salmonella . The PCR assay proved to be a highly specific and sensitive method for detecting Salmonella and the incorporation of a routine PCR test in conjunction with standard culture could be effective in providing a more accurate profile of the prevalence of this pathogen in broiler carcasses.

Harefuah, 2002 Aug, 141(8), 685 - 8, 763
{Salmonella virchow sacroiliitis and bacteremia in a child}; Genizi J et al.; A 2.5 years old girl was admitted because of high fever and limping that appeared two days after she had trauma to her right leg . Bone scan demonstrated increased uptake in the right sacroiliac joint, and CT demonstrated right sacroiliitis . Salmonella vircow was isolated from the blood culture . The patient recovered after a five weeks course of intravenous antibiotics . Salmonella sacroiliitis in children is rare, and only seven cases have been reported in the English literature in the last 40 years . We reviewed the literature dealing with pathophysiology diagnosis therapy and outcome of this infection.

Environ Microbiol, 2002 Sep, 4(9), 538 - 45
Mitigation of avian reproductive tract function by Salmonella enteritidis producing high-molecular-mass lipopolysaccharide; Parker CT et al.; Hens were infected with a wild-type Salmonella enteritidis and its wzz mutant, which lacked the ability to make high-molecular-mass lipopolysaccharide (LPS), in six experiments paired by dosage and route of exposure . Involution of the reproductive tract occurred in 86% of hens that were injected subcutaneously with 108 cfu of the wild-type strain, but none did so when injected with the wzz mutant . In spite of the lack of a specific effect on the reproductive tract, infection of hens with the mutant produced more contaminated eggs and heterophilic granulomas in developing ova (yolks) than wild type; thus, overall, the mutant appeared to be more virulent except after intravenous injection . The mutant also decreased shell quality more often than wild type, regardless of dosage or route of infection . These results suggest that egg-contaminating Salmonella enteritidis that produces high-molecular-mass LPS mitigates signs of illness in poultry by altering the response of the avian reproductive tract to infection, but without altering the incidence of egg contamination following bacteraemia . Further research is warranted to determine whether analyses of shell quality might aid in identification of flocks at risk of producing contaminated eggs.

Plasmid, 2002 Jul, 48(1), 59 - 63
Sequence analysis and characterization of plasmid pSFD10 from Salmonella choleraesuis; Liu M et al.; The nucleotide sequence of a small plasmid, designated pSFD10, is isolated from the vaccine strain Salmonella choleraesuis C500 in China, has been determined . This plasmid is 4091 bp long with a total G+C content of 51.4%, which is in the range of Salmonella genomic DNA . Analysis of the complete nucleotide sequence reveals that pSFD10 has a high degree of similarity to ColE1-type plasmid, having the possible cer and rom genes, and a putative mobilization origin of ColE1-type . Plasmid pSFD10 possesses six main open reading frames (ORFs), five of which have a very high degree of amino acid identity to ColE1-type plasmid gene products involved in mobilization and copy number control . The other ORF (ORF6) encodes a putative protein, which has 49% homology to the invasion plasmid antigen J protein (IpaJ) secreted by the type III secretion apparatus of Shigella flexneri . In addition, pSFD10 belongs to a different incompatibility group than ColE1-type and pMB1-type to which it is related . Plasmid pSFD10 can be mobilized by the plasmid RP4 in E . coli.

Rev Inst Med Trop Sao Paulo, 2002 Jul-Aug, 44(4), 235 - 7
Isolation of Salmonella enterica and serologic reactivity to Leptospira interrogans in opossums (Didelphis virginiana) from Yucatán, México; Ruiz-Pina HA et al.; The presence of Salmonella enterica and serologic evidence of infection by Leptospira interrogans, were detected in the opossum Didelphis virginiana in a semi-urban locality of the Yucatan State, Mexico . Ninety-one opossums were captured during the period April 1996 and May 1998 . From a total of 17 feces samples, four Salmonella enterica subsp . enterica serotypes (Sandiego, Newport, Anatum, and Minnesota), and one Salmonella enterica subsp . arizonae serovar O44:Z4,Z23:- were isolated . Some opossums presented mixed infections . From 81 sera samples, four (4.9%) were positive to antibodies to Leptospira serovars pomona and wolfii . Both animals infected with Salmonella enterica and those serologically positive to Leptospira interrogans were captured in peridomestic habitat . Opossums infected with Salmonella enterica, were captured in dry season, and those seropositive to Leptospira interrogans during the rainy season . The implications of infection and reactivity of these zoonotic pathogens in D . virginiana in the Yucatan state are briefly discussed.

J Pediatr, 2002 Sep, 141(3), 381 - 7
Infection due to extended-spectrum beta-lactamase-producing Salmonella enterica subsp . enterica serotype infantis in a neonatal unit; Pessoa-Silva CL et al.; OBJECTIVE: To describe the investigation and control of an outbreak of extended-spectrum beta-lactamase producing Salmonella enterica subsp . enterica serotype Infantis in a neonatal unit in Brazil . METHODS: A case-control study for risk factors for Salmonella Infantis systemic infection, environmental cultures, and evaluation of staffing and overcrowding and an assessment of infection control practices were performed . RESULTS: During July 1998 to June 1999, 140 Salmonella Infantis culture-positive patients were identified in the neonatal unit . Presence of a peripheral intravascular catheter was identified as an independent risk factor (odds ratio = 4.98; 95% CI = 1.59-19.31; P =.01) and each 250-g increase in birth weight as a protective factor (odds ratio = 0.76; 95% CI = 0.57-0.95; P =.03) . Hospital stay was significantly longer and costs higher in case patients than in control patients . Salmonella Infantis was isolated from multiple environmental sources . Neonatal unit personnel were observed to make several breaks in infection control practices . The unit was understaffed and overcrowded . Prompt case identification, cohorting of patients, enhanced staff hand hygiene, and environmental cleaning terminated the outbreak . CONCLUSIONS: Inadequate infection control practices, nursery overcrowding, and understaffing can have an adverse effect on patient morbidity, mortality rates, and hospital cost.

J Bacteriol, 2002 Oct, 184(19), 5468 - 78
Mutational analysis of the Escherichia coli PhoQ sensor kinase: differences with the Salmonella enterica serovar Typhimurium PhoQ protein and in the mechanism of Mg2+ and Ca2+ sensing; Regelmann AG et al.; The PhoP-PhoQ two-component system plays a role in Mg2+ homeostasis and/or the virulence properties of a number of bacterial species . A Salmonella enterica serovar Typhimurium PhoQ sensor kinase mutant, in which the threonine at residue 48 in the periplasmic sensor domain is changed to an isoleucine, was shown previously to result in elevated expression of PhoP-activated genes and to affect mouse virulence, epithelial cell invasion, and sensitivity to macrophage killing . We characterized a complete set of proteins having amino acid substitutions at position 48 in the closely related Escherichia coli PhoQ protein . Numerous mutant proteins having amino acid substitutions with side chains of various sizes and characters displayed signaling phenotypes similar to that of the wild-type protein, indicating that interactions mediated by the wild-type threonine side chain are not required for normal protein function . Changes to amino acids with aromatic side chains had little impact on signaling in response to extracellular Mg2+ but resulted in reduced sensitivity to extracellular Ca2+, suggesting that the mechanisms of signal transduction in response to these two divalent cations are different . Surprisingly, the Ile48 protein displayed a defective phenotype rather than the hyperactive phenotype seen with the S . enterica serovar Typhimurium protein . We also describe a mutant PhoQ protein lacking the extracellular sensor domain with a defect in the ability to activate PhoP . The defect does not appear to be due to reduced autokinase activity but rather appears to be due to an effect on the stability of the aspartyl-phosphate bond of phospho-PhoP.

J Bacteriol, 2002 Oct, 184(19), 5307 - 16
Adaptation of sucrose metabolism in the Escherichia coli wild-type strain EC3132; Jahreis K et al.; Although Escherichia coli strain EC3132 possesses a chromosomally encoded sucrose metabolic pathway, its growth on low sucrose concentrations (5 mM) is unusually slow, with a doubling time of 20 h . In this report we describe the subcloning and further characterization of the corresponding csc genes and adjacent genes . The csc regulon comprises three genes for a sucrose permease, a fructokinase, and a sucrose hydrolase (genes cscB, cscK, and cscA, respectively) . The genes are arranged in two operons and are negatively controlled at the transcriptional level by the repressor CscR . Furthermore, csc gene expression was found to be cyclic AMP-CrpA dependent . A comparison of the genomic sequences of the E . coli strains EC3132, K-12, and O157:H7 in addition to Salmonella enterica serovar Typhimurium LT2 revealed that the csc genes are located in a hot spot region for chromosomal rearrangements in enteric bacteria . The comparison further indicated that the csc genes might have been transferred relatively recently to the E . coli wild-type EC3132 at around the time when the different strains of the enteric bacteria diverged . We found evidence that a mobile genetic element, which used the gene argW for site-specific integration into the chromosome, was probably involved in this horizontal gene transfer and that the csc genes are still in the process of optimal adaptation to the new host . Selection for such adaptational mutants growing faster on low sucrose concentrations gave three different classes of mutants . One class comprised cscR(Con) mutations that expressed all csc genes constitutively . The second class constituted a cscKo operator mutation, which became inducible for csc gene expression at low sucrose concentrations . The third class was found to be a mutation in the sucrose permease that caused an increase in transport activity.

J Bacteriol, 2002 Oct, 184(19), 5234 - 9
Identification of GtgE, a novel virulence factor encoded on the Gifsy-2 bacteriophage of Salmonella enterica serovar Typhimurium; Ho TD et al.; The Gifsy-2 temperate bacteriophage of Salmonella enterica serovar Typhimurium contributes significantly to the pathogenicity of strains that carry it as a prophage . Previous studies have shown that Gifsy-2 encodes SodCI, a periplasmic Cu/Zn superoxide dismutase, and at least one additional virulence factor . Gifsy-2 encodes a Salmonella pathogenicity island 2 type III secreted effector protein . Sequence analysis of the Gifsy-2 genome also identifies several open reading frames with homology to those of known virulence genes . However, we found that null mutations in these genes did not individually have a significant effect on the ability of S . enterica serovar Typhimurium to establish a systemic infection in mice . Using deletion analysis, we have identified a gene, gtgE, which is necessary for the full virulence of S . enterica serovar Typhimurium Gifsy-2 lysogens . Together, GtgE and SodCI account for the contribution of Gifsy-2 to S . enterica serovar Typhimurium virulence in the murine model.

J Bacteriol, 2002 Oct, 184(19), 5214 - 22
Role of OxyR as a peroxide-sensing positive regulator in Streptomyces coelicolor A3(2); Hahn JS et al.; Genes encoding a homolog of Escherichia coli OxyR (oxyR) and an alkyl hydroperoxide reductase system (ahpC and ahpD) have been isolated from Streptomyces coelicolor A3(2) . The ahpC and ahpD genes constitute an operon transcribed divergently from the oxyR gene . Expression of both ahpCD and oxyR genes was maximal at early exponential phase and decreased rapidly as cells entered mid-exponential phase . Overproduction of OxyR in Streptomyces lividans conferred resistance against cumene hydroperoxide and H2O2 . The oxyR mutant produced fewer ahpCD and oxyR transcripts than the wild type, suggesting that OxyR acts as a positive regulator for their expression . Both oxyR and ahpCD transcripts increased more than fivefold within 10 min of H2O2 treatment and decreased to the normal level in 50 min, with kinetics similar to those of the CatR-mediated induction of the catalase A gene (catA) by H2O2 . The oxyR mutant failed to induce oxyR and ahpCD genes in response to H2O2, indicating that OxyR is the modulator for the H2O2-dependent induction of these genes . Purified OxyR protein bound specifically to the intergenic region between ahpC and oxyR, suggesting its direct role in regulating these genes . These results demonstrate that in S . coelicolor OxyR mediates H2O2 induction of its own gene and genes for alkyl hydroperoxide reductase system, but not the catalase gene (catA), unlike in Escherichia coli and Salmonella enterica serovar Typhimurium.

J Mol Biol, 2002 Sep 13, 322(2), 281 - 90
Structural properties of FliH, an ATPase regulatory component of the Salmonella type III flagellar export apparatus; Minamino T et al.; FliH is a regulatory component for FliI, the ATPase that is responsible for driving flagellar protein export in Salmonella . FliH consists of 235 amino acid residues, has a quite elongated shape, exists as a homodimer and together with FliI forms a heterotrimer . Here, we have investigated the structural properties of the FliH homodimer in further detail . Like intact His-tagged FliH homodimer, fragment His-FliH(N2) (consisting of the first 102 amino acid residues of FliH), exhibited anomalous elution behavior in gel filtration chromatography; the same was true of His-FliH(C1) (consisting of amino acid residues 119-235), but to a much lesser degree . Thus the elongated shape of FliH appears to derive primarily from its N-terminal region . A deletion version of N-His-FliH, lacking amino acid residues 101-140, does not dimerize and so we were able to establish the gel filtration properties of an almost full-size monomeric form; it also exhibited anomalous elution behavior . We performed trypsin proteolysis of the FliH homodimer and subjected the cleavage products to gel filtration chromatography . FliH was degraded by trypsin and a contaminating protease into two stable fragments: FliH(Prt1) (missing both the first ten and the last 12 amino acid residues), and FliH(Prt2) (missing both the first ten and the last 63 amino acid residues); however, substantial amounts remained undigested even after 24 hours . Under native conditions, both FliH(Prt1) and FliH(Prt2) co-eluted with undigested His-FliH from the gel filtration column, indicating that the fragments exist as a hybrid dimer with intact FliH . These results suggest that the two subunits within the dimer differ in their proteolytic susceptibility . No heterotrimer was observed by gel filtration chromatography when His-FliI was mixed with either His-FliH/FliH(Prt1) or His-FliH/FliH(Prt2) hybrid dimers . A hybrid dimer of FliH and His-FliHDelta1 (lacking the first ten amino acid residues) retained the ability to form a complex with His-FliI . In contrast, hybrid dimers consisting of FliH and either His-FliH(W223ochre) or His-FliH(V172ochre) failed to complex to His-FliI, demonstrating that the C-terminal region of both FliH monomers within the FliH dimer are required for heterotrimer formation.

Trends Microbiol, 2002 Sep, 10(9), 391 - 2
Salmonella selectively stops traffic; Fang F et al.; The intracellular pathogen Salmonella replicates in infected host cells within a specialized vacuole referred to as the Salmonella-containing vacuole (SCV) . Effector molecules encoded by the Salmonella pathogenicity island 2 (SPI-2) type III secretion system (TTSS) are essential for Salmonella to survive in the intracellular environment . It was previously shown that SPI-2 allows Salmonella to inhibit the recruitment of NADPH phagocyte oxidase-containing vesicles to SCVs . New research has now revealed that SPI-2 effectors also interfere with the colocalization of inducible nitric oxide synthase (iNOS) to SCVs, thus protecting the pathogen from the antimicrobial actions of reactive nitrogen species.

Salud Publica Mex, 2002 Jul-Aug, 44(4), 297 - 302
{Outbreak caused by Escherichia coli in Chalco, Mexico}; Cortes-Ortiz IA et al.; OBJECTIVE: To identify the etiologic agent responsible for a disease outbreak following an overflow of sewage water in Valle de Chalco, Mexico . MATERIAL AND METHODS: A retrospective cross-sectional study was carried out . Rectal samples were collected from the population of Chalco valley, who suffered from diarrhea and vomiting during a natural disaster that took place on May 31, 2000 . The Instituto de Diagnostico y Referencia Epidemiologicos (Epidemic Reference and Diagnosis Institute, InDRE, Ministry of Health), received 1521 rectal swab samples from diarrhea cases, to test for E . coli strains . Statistical analysis was performed to find a difference of proportions between cases and non-cases (chi-squared test) . ETEC, EIEC, EPEC and EHEC pathogenic E . coli groups were hybridized by colony blot . RESULTS: Strains isolated were ETEC (62.2%), EIEC (0.84%), EPEC (0.84%), and EHEC non-O157:H7 (0.08%); there was no hybridization in 36.02% of E . coli strains . Other isolated microorganisms were Salmonella spp (0.45%) and Shigella spp (0.06%) . CONCLUSIONS: Enterotoxigenic E . coli was the most likely etiologic agent . Sanitary control strategies should be targeted to preventing outbreaks caused by this pathogenic agent . The English version of this paper is available at: http://www.insp.mx/salud/index.html.

J Egypt Soc Parasitol, 2002 Aug, 32(2), 355 - 60
Delayed Salmonella bacteriuria in a patient infected with Schistosoma haematobium; Bouree P et al.; The authors report a case of Schistosoma haematobium infection with delayed occurrence of Salmonella bacteriuria following treatment of schistosomiasis . Standard models of interaction between these two pathogens may not be fully satisfactory in such a case of co-infection . The role played by a decreased host immune response following schistosomiasis may thus be highlighted to explain a delayed or prolonged infection with Salmonella.

Microbiology, 2002 Sep, 148(Pt 9), 2727 - 33
ClpP is involved in the stress response and degradation of misfolded proteins in Salmonella enterica serovar Typhimurium; Thomsen LE et al.; Components of the ATP-dependent Clp protease complex are found in a wide range of prokaryotic cells and they are often expressed as part of the cellular stress response . To investigate the physiological role of the proteolytic subunit, ClpP, in Salmonella enterica serovar Typhimurium (S . typhimurium) an in-frame deletion of the clpP gene was constructed . Growth experiments revealed that clpP is important for the ability of S . typhimurium to grow under various stressful conditions, such as low pH, elevated temperature and high salt concentrations . Since the stationary-phase sigma factor, RpoS, is a target of the Clp proteolytic complex, the effect of the clpP deletion in the absence of RpoS was examined; it was observed that growth of the S . typhimurium clpP mutant is affected in both an RpoS-dependent and an RpoS-independent manner . Analysis of the degradation of abnormal puromycyl-containing polypeptides showed that ClpP participates in the proteolysis of such proteins in S . typhimurium . These findings prompted an investigation of the growth of an Escherichia coli clpP mutant under various stress conditions . The growth of this E . coli mutant was affected by heat, salt and low pH, although not to the same extent as observed for the S . typhimurium clpP mutant . The results of this study indicate that the S . typhimurium clpP mutant is generally more sensitive to environmental stress than the E . coli clpP mutant and it is proposed that this is due to a reduced ability to degrade misfolded proteins generated under these conditions.

Microbiology, 2002 Sep, 148(Pt 9), 2717 - 26
Active but nonculturable cells of Salmonella enterica serovar Typhimurium do not infect or colonize mice; Smith RJ et al.; The possibility that nonculturable cells of a normally culturable bacterial pathogen may constitute a source or reservoir for infective disease was investigated . In multiple experiments and with careful attention to the statistical limitations of the assays used, Salmonella enterica serovar Typhimurium cells rendered nonculturable by carbon and nitrogen stress in the presence of chloramphenicol were administered orally and intraperitoneally to over 300 female BALB/c mice . Neither infection nor colonization was detected in these studies, even when active but nonculturable (ABNC) cells, as defined by the Kogure cell elongation assay, were present in the inoculum . Doses of ABNC cells exceeding the oral and intraperitoneal LD(50) values by 3.5 and 2 orders of magnitude, respectively, were administered . It was concluded that ABNC cells of the salmonella strains used could not be considered potentially infective and that their detection in samples from material being evaluated as a potential source or reservoir of infection by the Kogure test does not specifically represent an infective hazard.

Microbiology, 2002 Sep, 148(Pt 9), 2705 - 15
Growth and killing of a Salmonella enterica serovar Typhimurium sifA mutant strain in the cytosol of different host cell lines; Beuzon CR et al.; Intracellular pathogens have developed different mechanisms which enable their survival and replication within the host cells . Some survive and replicate within a membrane-bound vacuole modified by the bacteria to support microbial growth (e.g . Salmonella enterica serovar Typhimurium), whereas others escape from the vacuole into the host cell cytosol, where they proliferate (e.g . Listeria monocytogenes) . In this study a Salmonella strain carrying a mutation in sifA which is released from the vacuole was used to analyse Salmonella survival and replication within the cytosol of several cell lines . It was found that Salmonella replicates within the cytosol of epithelial cells at a higher rate than that achieved when replicating within the vacuole, but is defective for replication in the cytosol of fibroblasts or macrophages . Using an aroC purD double mutant strain which does not replicate within host cells, it was shown that Salmonella encounters a killing activity within the cytosol of macrophages . Furthermore, in vitro experiments using cytosol extracted from either infected or uninfected macrophages suggested that this activity is activated upon Salmonella infection.

Vaccine, 2002 Sep 10, 20(27-28), 3239 - 43
The effect of recombinant plasmids on in vivo colonisation of Salmonella enterica serovar Typhimurium strains is not reflected by in vitro cellular invasion assays; Garmory HS et al.; Attenuated strains of Salmonella enterica serovar Typhimurium are used as carriers of heterologous antigens as candidate oral vaccines and, more recently, as carriers of DNA vaccines . In this study, recombinant Salmonella strains that were altered in their ability to colonise murine tissues in vivo when compared to parent strains were not, however, equally altered in their ability to invade murine cells in vitro . These results suggest that in vitro invasion studies may not be a representative model for colonisation of tissues in vivo, and that in vitro studies should ideally be used in conjunction with in vivo studies for the assessment of potential Salmonella vaccines.

Ren Fail, 2002 Jul, 24(4), 535 - 8
Diarrhea associated acute renal failure in a patient with Salmonella enteritidis sepsis; Lin WR et al.; Salmonella enteritidis infection occurs primarily in animals and often results in self-limited gastroenteritis in accidental cross contamination in human . However, the acute renal failure could be a rare but serious complication of the S . enteritidis infection . We report one case of acute renal failure from severe dehydration caused by S . enteritidis food poisoning . The acute renal failure completely recovered after hydration and antibiotic treatment.

Epidemiol Infect, 2002 Aug, 129(1), 35 - 9
An outbreak of Salmonella enteritidis phage type 34a infection in primary school children: the use of visual aids and food preferences to overcome recall bias in a case control study; Linnane E et al.; Outbreaks of infectious intestinal disease are common in schools . Case control studies are useful in the investigation of infectious disease outbreaks but the time interval between illness and investigation can lead to recall bias, particularly in young children . We describe an outbreak of Salmonella enteritidis phage type 34a infection involving 54 clinical cases in two adjacent schools, and a novel approach to overcome recall bias . The likely dates of infection were identified from the epidemic curve . We created a visual display of the menu from those days and asked 9 cases and 18 matched controls to identify their food preferences from this display . Preference for chocolate mouse was significantly associated with illness (P = 0.006) . The results of the case control study agreed with the findings of the environmental investigation . We believe our approach could be used in other circumstances, where subjects are young children or recall bias is a concern.

Epidemiol Infect, 2002 Aug, 129(1), 29 - 34
Decline in epidemic of multidrug resistant Salmonella typhi is not associated with increased incidence of antibiotic-susceptible strain in Bangladesh; Rahman M et al.; Since 1987, multidrug resistant (MDR) strains of Salmonella Typhi, resistant simultaneously to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole, have caused epidemics of severe typhoid fever in Asia and Africa . A retrospective analysis of blood culture results (1989-96) in a Diarrhoea Treatment Centre in Dhaka, Bangladesh detected MDR strains in 0.3% (8 of 2793) of samples in 1990 . The isolation rate peaked to 3.2% (240 of 7501) in 1994 (P < 0.01) and decreased to 1.8% (165 of 9348) in 1995 and further to 1.0% (82 of 8587) in 1996 (P < 0.01 compared to 1994) indicating the emergence and decline of MDR typhoid epidemic . Ten of 15 MDR strains tested had a 176 kb conjugative R plasmid that mediates resistance to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole to Escherichia coli K12 . Unlike MDR strains, the isolation rate (approximately 3.3%) of susceptible S . Typhi remained remarkably unchanged during the study . The significant decrease in isolation of MDR strains suggests that cheaper and effective first-line antibiotics may re-emerge as drugs of choice for the treatment of typhoid fever in Bangladesh.

Epidemiol Infect, 2002 Aug, 129(1), 19 - 27
Human salmonellosis associated with young poultry from a contaminated hatchery in Michigan and the resulting public health interventions, 1999 and 2000; Wilkins MJ et al.; Although approximately 95% of disease caused by nontyphoidal salmonella is transmitted by foodborne vehicles, four documented salmonella outbreaks in the 1990s have been traced to contact with young poultry . No environmental studies of source hatcheries were completed . This case-control study was performed by comparing culture-confirmed Salmonella Infantis in Michigan residents, identified between May and July 1999, with two age- and neighbourhood-matched controls . Eighty environmental and bird tissue samples were collected from an implicated hatchery; all salmonella isolates underwent pulsed-field gel electrophoresis (PFGE) analysis . The study included 19 case-patients sharing the same PFGE subtype and 37 matched controls . Within 5 days before illness onset, 74% of case-patients resided in households raising young poultry compared with 16% of controls (matched OR 19.5; 95% CI 2.9, 378.1) . Eight hatchery samples yielded Salmonella Infantis with PFGE subtypes matching the patients' isolates . This investigation identified birds from a single hatchery as the source of human illness and confirmed the link by matching PFGE patterns from humans, birds and the hatchery environment . Subsequent public health interventions reduced, but did not eliminate, transmission of poultry-associated salmonellosis . Five additional PFGE-linked cases were identified in Spring 2000, necessitating quarantine of the hatchery for depopulation, cleaning and disinfection.

Epidemiol Infect, 2002 Aug, 129(1), 155 - 61
Drug resistances in salmonella isolates from animal foods, italy 1998-2000; Mammina C et al.; We investigated the distribution of serotypes and patterns of drug resistance of 206 strains of salmonella isolated in southern Italy in the years 1998-2000 from raw food of animal origin, faeces of food animals and animal feed . To improve knowledge of mobile genetic elements carrying the resistance genes, some molecular features were also investigated within isolates resistant to three or more antibiotics . A high proportion of isolates, 52.2% and 37.7%, respectively, belonging to both Typhimurium and other serotypes of animal origin, proved to be multidrug resistant . The DT104 complex specific multidrug pattern of resistance was quite infrequent among isolates other than Typhimurium, but resistances to nalidixic acid and kanamycin were more frequent within these last ones (36.9% vs . 11.4% and 56.5% vs . 2.2%, respectively) . Class I integrons were detected in isolates of Typhimurium and seven different serotypes . The relevance of food animal environment as a drug resistance reservoir and animal food as a potential resistance gene vehicle between the farm and human ecological niches is confirmed by our findings.

Epidemiol Infect, 2002 Aug, 129(1), 1 - 8
Salmonella surveillance: a global survey of public health serotyping; Herikstad H et al.; To better understand the global epidemiology of salmonellosis and the national surveillance programmes used for salmonella infections in humans, we conducted a global survey of the 191 WHO Member States . We gathered information on the total number of salmonella isolates serotyped, and the 15 most commonly isolated serotypes from humans in 1990 and 1995 . Of the 104 countries that responded, 76 (73.1%) conducted public health surveillance for salmonella and 69 of these (90.8%) conducted serotyping as part of the surveillance . Fifty-nine countries (56.7% of those responding) provided information about the most commonly isolated serotypes in 1995 . Three serotypes, Enteritidis, Typhimurium and Typhi accounted for 76.1% of all isolates reported in 1995 . One of these three was the most common serotype identified in 93.2% of countries reporting data for that year . In 1995, Enteritidis was the most frequently isolated serotype in 35 countries, followed by Typhi (12 countries) and Typhimurium (8 countries) . The global pandemic of Salmonella Enteritidis continued to expand . The mean national proportion of all salmonella isolates that were Enteritidis increased globally from 25.6% in 1990 to 36.3% in 1995 . Serotyping is a frequently used component of a public health response to the global challenge of salmonellosis . Support for serotyping as part of national salmonella surveillance, and for rapid international communication of the results via a new WHO electronic website will help target future prevention strategies.

Poult Sci, 2002 Aug, 81(8), 1128 - 31
Detection of experimental Salmonella enteritidis and S . typhimurium infections in laying hens by fluorescence polarization assay for egg yolk antibodies; Gast RK et al.; Identifying infected laying flocks is a critical component in efforts to prevent eggborne transmission of Salmonella enteritidis to humans . In the present study, egg yolk samples from experimentally infected chickens were tested for specific antibodies with a very rapid fluorescence polarization assay using tracers prepared from the O-polysaccharides of S . enteritidis and S . typhimurium and a conventional ELISA using an S . enteritidis flagellin antigen . In two trials, groups of specific-pathogen-free laying hens were infected orally with 106 or 10(8) cfu of S . enteritidis (phage type 13a) or with 10(8) cfu of S . typhimurium . Eggs were collected during five weekly postinoculation intervals . Both fluorescence polarization and ELISA detected the majority of hens infected with S . enteritidis at either dose level, although they also frequently cross-reacted with samples from hens infected with S . typhimurium . Fluorescence polarization with an S . typhimurium tracer was likewise able to consistently detect S . typhimurium infection but also tended to cross-react with samples from hens infected with S . enteritidis . Fluorescence polarization appears to offer a simple and rapid alternative to conventional serological methodology, although concerns about specificity may limit the usefulness of antibody testing data.

Environ Mol Mutagen, 2002, 40(1), 1 - 17
Genotoxicity of naturally occurring indole compounds: correlation between covalent DNA binding and other genotoxicity tests; Reddy MV et al.; 3-Methylindole (3MI), melatonin (Mel), serotonin (Ser), and tryptamine (Tryp) were evaluated in vitro for their potential to induce DNA adducts, DNA strand breaks, chromosomal aberrations (Abs), inhibition of DNA synthesis, and mutations . All compounds produced DNA adducts in calf thymus DNA in the presence of rat liver S9 . In cultured rat hepatocytes, all produced DNA adducts but none induced DNA strand breaks . In Chinese hamster ovary cells, 3MI and Mel produced DNA adducts, Abs, and inhibition of DNA synthesis with and without S9, except that Mel without S9 did not form adducts . Ser formed DNA adducts, was an equivocal Abs inducer, and suppressed DNA synthesis . Tryp induced neither adducts nor Abs, but did suppress DNA synthesis with S9 . Ser and Tryp were less cytotoxic than 3MI and Mel . Mel, Ser, and Tryp failed to induce mutations in Salmonella and E . coli strains with or without S9 . 3MI and Mel produced DNA adducts but not mutations in Salmonella TA100 with S9 . 3MI and its metabolite indole 3-carbinol also did not induce mutations in a shuttle vector system in human cells . The lack of correlation between DNA adducts and other genotoxicity endpoints for these indole compounds may be due to the higher sensitivity of the (32)P-postlabeling adduct assay or it may indicate that the indole-DNA adducts per se are not mutagenic and are not able to induce strand breaks or alkali-labile lesions . The indole-induced Abs may result from cytotoxicity and suppression of DNA synthesis with minimal if any contribution from DNA adducts .

Toxic Rep Ser, 1992 Mar, 10, 1 - B7
NTP technical report on the toxicity studies of Ethylbenzene (Cas No . 100-41-4) in F344/N Rats and B6C3F1 Mice (Inhalation Studies); Chan P; Ethylbenzene is commonly used as a solvent and chemical intermediate and as an additive in some motor fuel formulations . Inhalation toxicology studies of ethylbenzene (99% pure) were conducted by exposing groups of F344/N rats and B6C3F1 mice of each sex to ethylbenzene vapor at chamber concentrations of 0, 100, 250, 500, 750, or 1000 ppm, 6 hours per day, 5 days per week for 13 weeks . No rats or mice died during the 13-week exposure . Body weight gains were slightly lower in the high dose groups of male and female rats, but the differences were not statistically significant . Absolute and relative kidney, liver, and lung weights were increased in the exposed rats, while weight increases occurred only in the livers of exposed mice . Chemically related histopathologic changes were not observed in any tissues of rats or mice . No changes were observed in the evaluation of sperm or vaginal cytology in rats or mice . Ethylbenzene was not mutagenic in Salmonella and did not induce chromosomal aberrations or sister chromatid exchanges in Chinese hamster ovary (CHO) cells in vitro, though it did induce trifluorothymidine resistance in mouse lymphoma cells at the highest concentration tested . Micronuclei assays in peripheral blood of mice were negative . Thus, there appears to be only minimal evidence of toxicity in F344/N rats and B6C3F1 mice exposed to ethylbenzene by inhalation at concentrations as high as to 1000 ppm for 13 weeks . Synonyms: EB, ethyl benzene, ethylbenzol, phenylethane . (NOTE: These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U.S . Public Health Service.)

Nat Genet, 2002 Sep, 32(1), 97 - 105
Genetics, cytokines and human infectious disease: lessons from weakly pathogenic mycobacteria and salmonellae; Ottenhoff TH et al.; Host genetic factors are important in determining the outcome of infections caused by intracellular pathogens, including mycobacteria and salmonellae, but until now have been poorly characterized . Recently, some individuals with severe infections due to otherwise weakly pathogenic mycobacteria (non-tuberculous mycobacteria or Mycobacterium bovis bacille Calmette-Guerin) or Salmonella species have been shown to be unable to produce or respond to interferon-gamma . This inability results from mutations in any of five genes encoding essential proteins of the type 1 cytokine cascade: interleukin-12p40, interleukin-12R beta 1, interferon-gamma R1, interferon-gamma R2 or STAT1 . Ten syndromes have thus far been identified . Recent insights in genetically controlled host defense and susceptibility to mycobacterial disease are discussed.

J Clin Microbiol, 2002 Sep, 40(9), 3530 - 1
A pilot with pain in his leg: thigh abscess caused by Salmonella enterica serotype Brandenburg; Bjorkman P et al.; Salmonella enterica serotype Brandenburg is one of the more uncommon serotypes isolated from patients with gastroenteritis . Few cases of extraintestinal infections with serotype Brandenburg have been documented . The first case of a serotype Brandenburg-dependent thigh abscess originating from an atherosclerotic pseudoaneurysm of the femoral artery is reported.

J Clin Microbiol, 2002 Sep, 40(9), 3502 - 5
Persistent endemicity of Salmonella bongori 48:z(35):--in Southern Italy: molecular characterization of human, animal, and environmental isolates; Giammanco GM et al.; From 1984 to 1999, we collected 31 isolates of the rare serovar Salmonella bongori 48:z(35):- in southern Italy . Twenty-four of the isolates were from cases of acute enteritis in humans . Pulsed-field gel electrophoresis analysis showed that all but one of our isolates were at least 80% similar . Our findings suggest that genetically related S . bongori 48:z(35):- strains are endemically circulating in southern Italy.

J Clin Microbiol, 2002 Sep, 40(9), 3497 - 8
Technical improvement to prevent DNA degradation of enteric pathogens in pulsed-field gel electrophoresis; Koort JM et al.; This study used a modified pulsed-field gel electrophoresis (PFGE) method with HEPES as a running buffer to prevent electrophoresis-related DNA degradation of nine Salmonella enterica subsp . enterica serovar Ohio, seven Salmonella serovar Newport, and two enterohemorrhagic Escherichia coli (non-O157) strains . All strains yielded identifiable bands with this method in contrast to a commonly applied PFGE method using Tris buffer.

J Clin Microbiol, 2002 Sep, 40(9), 3406 - 15
Fluorescent amplified fragment length polymorphism analysis of Salmonella enterica serovar typhimurium reveals phage-type- specific markers and potential for microarray typing; Hu H et al.; Fluorescent amplified fragment length polymorphism (AFLP) was applied to 46 Salmonella enterica serovar Typhimurium isolates of Australian origin comprising nine phage types, by using the restriction enzymes MseI and EcoRI and all 16 possible MseI +1-EcoRI +1 primer pair combinations . AFLP in the present study showed a very good discrimination power with a Simpson index of diversity of 0.98, and 35 different AFLP patterns were observed in the 46 isolates . AFLP grouped most serovar Typhimurium isolates by phage type and enabled differentiation of phage types . Furthermore, 84 phage-type-specific polymorphic AFLP fragments, for which presence or absence correlated with phage type (including 25 with one exception to phage type specificity) were observed in the 46 strains studied . Eighteen phage-type-specific AFLP fragments were cloned and sequenced . Fifteen are of known genes or have a homologue in the databases . Three sequences are plasmid related, eight are phage related, and four relate to chromosomal genes . Twelve of the 18 fragments are polymorphic because the DNA is present or absent as indicated by Southern hybridization, and we see good potential to use sequences of these fragments as the basis for multiplex PCR and development of a microarray-based molecular phage-typing method for serovar Typhimurium.

J Clin Microbiol, 2002 Sep, 40(9), 3184 - 91
Molecular characterization of multiresistant d-tartrate-positive Salmonella enterica serovar paratyphi B isolates; Miko A et al.; Since 1996, the National Salmonella Reference Laboratory of Germany has received an increasing number of Salmonella enterica subsp . enterica serovar Paratyphi B isolates . Nearly all of these belonged to the dextrorotatory tartrate-positive variant (S . enterica subsp . enterica serovar Paratyphi B dT(+)), formerly called S . enterica subsp . enterica serovar Java . A total of 55 selected contemporary and older S . enterica subsp . enterica serovar Paratyphi B dT(+) isolates were analyzed by plasmid profiling, antimicrobial resistance testing, pulsed-field gel electrophoresis, IS200 profiling, and PCR-based detection of integrons . The results showed a high genetic heterogeneity among 10 old strains obtained from 1960 to 1993 . In the following years, however, new distinct multiresistant S . enterica subsp . enterica serovar Paratyphi B dT(+) clones emerged, and one clonal lineage successfully displaced the older ones . Since 1994, 88% of the isolates investigated were multiple drug resistant . Today, a particular clone predominates in some German poultry production lines, poultry products, and various other sources . It was also detected in contemporary isolates from two neighboring countries as well.

J Clin Microbiol, 2002 Sep, 40(9), 3121 - 6
Emergence of Klebsiella pneumoniae isolates producing inducible DHA-1 beta-lactamase in a university hospital in Taiwan; Yan JJ et al.; Ten nonrepetitive clinical isolates of Klebsiella pneumoniae exhibiting an unusual inducible beta-lactam resistance phenotype were identified between January 1999 and September 2001 in a university hospital in Taiwan . In the presence of 2 micro g of clavulanic acid, the isolates showed a one to four twofold concentration increase in the MICs of ceftazidime, cefotaxime, and aztreonam but remained susceptible to cefepime (MICs, </=0.5 micro g/ml) and imipenem (MICs, </=0.5 micro g/ml) . PCR, sequence analysis, and isoelectric focusing revealed production by these isolates of TEM-1, SHV-11, and DHA-1, a plasmid-encoded inducible AmpC beta-lactamase originally found in a Salmonella enterica serovar Enteritidis strain . Transfer of the resistance by conjugation experiments was not successful, but Southern hybridization showed that bla(DHA-1) was located on 70-kb plasmids, suggesting that the bla(DHA-1)-containing plasmids in the K . pneumoniae isolates were non-self-transmissible . Five isolates were recovered from patients in two surgery wards and two intensive care units . Acquisition of the DHA-1 producers could be traced back to previous hospitalizations 1 to 5 months earlier for the other five patients . Six and seven patterns among the isolates were demonstrated by plasmid analysis and ribotyping, respectively, indicating that the spread of the DHA-1 producers was due to both horizontal transfer of bla(DHA-1) and dissemination of endemic clones.

Fish Shellfish Immunol, 2002 Jul, 13(1), 27 - 45
Different bacterial lipopolysaccharides as toxicants and stressors in the shrimp Palaemon elegans; Lorenzon S et al.; This study compares the in vivo haemocytic response of shrimp, Palaemon elegans (Rathke) to different types of LPS injection . In particular it investigates to what degree and speed the haemocytopenia varies between LPSs from different sources . It further compares the tolerated doses of different LPSs in these animals and finds substantial differences in the various toxicity types . The work then relates this to blood glucose levels and stress-linked variations in glycaemic status . The order of LPS decreasing toxicity determined by LD50 at 96 h was: Salmonella enteritidis, Serratia marcescens, Pseudomonas aeruginosa 10, Escherichia coli K-235 and E . coli 0111:B4 . Eyestalkless animals were more sensitive to LPS . The effects of injected LPS on circulating total blood cell count (THC) was tested . The results show that LPS caused a decrease in THC 8 h after injection and then the THC returned to the initial level and this effect depended on the LPS tested . E . coli K-235 was the most effective in causing haemocytopenia followed by E . coli 0111:B4, S . enteritidis, S . marcescens, and P . aeruginosa 10 . Moreover, LPS-induced increases in the blood glucose level and the time and dose related curves of response obtained depended on the type of LPS tested . E . coli K-235 LPS was again the most effective in elevating blood glucose followed by E . coli 0111:B4, S . marcescens, S . enteritidis and then P . aeruginosa 10 . No significant hyperglycaemia was induced in eyestalkless animals . An inverse order relationship between toxicity (LD50) and stress responses (hyperglycaemia and THC decrease) may suggest a defensive and adaptive role of the latter in occasional septicaemia.

J Dairy Sci, 2002 Jul, 85(7), 1829 - 38
Relationship between content of crude protein in rations for dairy cows and milk yield, concentration of urea in milk and ammonia emissions; Frank B et al.; During recent decades, efforts have been made in several countries to diminish the negative environmental influence of dairy production . The main focus has been on nitrogen and phosphorus . Modern dairy production in Western Europe is often based on imported feed-stuffs, mostly protein-rich feeds . In Sweden at least, it is wished that the use of imported feedstuffs in animal production will decrease due to the risk of contamination with Salmonella and the ban of using GMO crops in Swedish dairy production . An experiment was carried out to investigate whether a lower content of crude protein in the diet would decrease the ammonia release from cow manure and whether a well-balanced diet using only feedstuffs of Swedish origin would maintain milk production . Five treatments were arranged in a Latin square design . Two different protein supplements made of ingredients of Swedish origin were each fed at two protein levels, and a fifth imported commercial protein mix was fed at the higher level . The treatments with low protein levels (13.1 to 13.5%) had a significantly lower milk yield, kilograms of ECM, but, on the other hand the net profit, milk income minus feed cost was nearly the same in all treatments except diet C, which had lower feed cost but also lower net profit due to lower milk yield . The content of urea in milk was higher with diets high in crude protein (17%) content . A decreased protein level in the diets did not influence the content of casein or whey protein, but the commercial concentrate showed a tendency to give lower values than the Swedish mixtures . The low protein diets gave significantly lower ammonia release from manure compared with the high protein diets . There were no production differences between the diets of Swedish feeds compared with the imported control . The readily fermentable beet pulp should have helped cows use the higher N diet more efficiently and increased the response . This gives the rumen microbes a possibility to match the inflow of protein with carbohydrates . Income over feed costs shows that it is possible to compile diets using products of Swedish origin and still be competitive . On the other hand, this structure may change quickly due to altered world market prices.

Cent Afr J Med, 2001 Jun, 47(6), 155 - 8
Anti-Salmonella activity of medicinal plants from Cameroon; Nkuo-Akenji T et al.; OBJECTIVES: To evaluate the effects of herbal extracts derived from plants commonly prescribed by traditional practitioners for the treatment of typhoid fever . DESIGN: A cross sectional study . SETTING: Departments of Life Sciences and Chemistry, University of Buea, Cameroon . SUBJECTS: Methanol extracts of plant parts commonly used in Cameroon for the treatment of typhoid fever . MAIN OUTCOME MEASURES: Antimicrobial activity was tested using the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assays . RESULTS: Methanol extracts of plant parts commonly used in Cameroon for the treatment of typhoid fever were tested for antibacterial activity against Salmonella typhi, S . paratyphi and S . typhimurium . The formulations used were: 1) Formulation A comprising Cymbogogon citratus leaves, Carica papaya leaves, and Zea mays silk . 2) Formulation B comprising C . papaya roots, Mangifera indica leaves, Citrus limon fruit and C . citratus leaves . 3) C . papaya leaves . 4) Emilia coccinea whole plant . 5) Comelina bengalensis leaves . 6) Telfaria occidentalis leaves . 7) Gossypium arboreum whole plant . Antimicrobial activity was tested using the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assays . Generally, Formulation A elicited inhibitory activity at a lower range of 0.02 to 0.06 mg/ml . Similarly, Formulation B elicited bacterial activity at the lowest range of 0.06 to 0.25 mg/ml . C . bengalensis leaves on the other hand, showed the lowest activity with a concentration range of 0.132 to 2.0 mg/ml and 1 to 4 mg/ml in MIC and MBC assays respectively . S . paratyphi was most sensitive to the formulations (concentration range of 0.02 to 1 mg/ml in both MIC and MBC assays) while S . typhimurium was the least sensitive and concentrations of up to 4 mg/ml were required to be bactericidal . CONCLUSION: It is concluded that plant extracts with low MIC and MBC values (1 mg/ml and lower) may contain compounds with therapeutic activity.

Clin Microbiol Infect, 2002 Jul, 8(7), 427 - 30
Salmonella prosthetic joint septic arthritis; Day LJ et al.; We describe a case of Salmonella enteritidis infection of a prosthetic knee joint that was cured with ceftriaxone therapy for 6 weeks and replacement of the tibial component of the prosthesis . Eleven other cases of salmonella prosthetic joint infection have been reported in the English-language literature . Five infections occurred within 20 days of prosthesis placement, and seven occurred several months to years later; ten of 12 infections involved hip prostheses . Nine of 12 patients who had prosthesis removal were cured of the infection . Two of the three patients with retention of the prosthesis required long-term suppressive antibiotic therapy.

East Mediterr Health J, 2000 Sep-Nov, 6(5-6), 1107 - 13
Antibiotic resistance of Moroccan strains of Salmonella enteritidis isolated between 1996 and 1997; Rouahi N et al.; Antimicrobial resistance is a worldwide problem . The antibiotic resistance of Moroccan strains of Salmonella enteritidis was investigated from 1996 to 1997 . A total of 51 strains were collected within this period, 31 derived from human sources and 20 from food . Of the 31 human strains, 10 were resistant to antibiotics; 4 were resistant to two or more antibiotics . Of the 20 food strains, 11 were resistant to antibiotics; 6 were resistant to two or more antibiotics . The results are similar to those obtained from strains isolated from other Mediterranean countries.

J Biol Chem, 2002 Nov 1, 277(44), 42151 - 6 Epub 2002 Aug 23.
Allosteric enhancement of adaptational demethylation by a carboxyl-terminal sequence on chemoreceptors; Barnakov AN et al.; Sensory adaptation in bacterial chemotaxis is mediated by covalent modification of chemoreceptors . Specific glutamyl residues are methylated and demethylated in reactions catalyzed by methyltransferase CheR and methylesterase CheB . In Escherichia coli and Salmonella enterica serovar typhimurium, efficient adaptational modification by either enzyme is dependent on a conserved pentapeptide sequence at the chemoreceptor carboxyl terminus, a position distant from the sites of modification . For CheR-catalyzed methylation, previous work demonstrated that this sequence acts as a high affinity docking site, enhancing methylation by increasing enzyme concentration near methyl-accepting glutamates . We investigated pentapeptide-mediated enhancement of CheB-catalyzed demethylation and found it occurred by a distinctly different mechanism . Assays of binding between CheB and the pentapeptide sequence showed that it was too weak to have a significant effect on local enzyme concentration . Kinetic analyses revealed that interaction of the sequence and the methylesterase enhanced the rate constant of demethylation not the Michaelis constant . This allosteric activation occurred if the sequence was attached to chemoreceptor, but hardly at all if it was present as an isolated peptide . In addition, free peptide inhibited demethylation of the native receptor carrying the pentapeptide sequence at its carboxyl terminus . These observations imply that the allosteric change is transmitted through the protein substrate, not the enzyme.

J Bacteriol, 2002 Sep, 184(18), 4971 - 80
SpiC is required for translocation of Salmonella pathogenicity island 2 effectors and secretion of translocon proteins SseB and SseC; Freeman JA et al.; The Salmonella pathogenicity island 2 (SPI2) type III secretion system (TTSS) promotes Salmonella enterica serovar Typhimurium virulence for mice and increased survival and replication within eukaryotic cells . After phagocytosis, Salmonella serovar Typhimurium assembles the SPI2 TTSS to translocate over a dozen effector proteins across the phagosome membrane . SpiC has been previously shown to be a translocated effector with a large contribution to virulence (K . Uchiya, M . A . Barbieri, K . Funato, A . H . Shah, P . D . Stahl, and E . A . Groisman, EMBO J . 18:3924-3933, 1999) . This report demonstrates by competitive index that the virulence phenotype of a spiC mutant is equivalent to that of a secretion component mutant . In addition, translocation of SPI2 effector proteins was shown to require SpiC . Thus, the severe virulence phenotype resulting from deletion of spiC is likely due to the inability to translocate all SPI2 effectors . SpiC was also required to secrete translocon proteins SseB and SseC but not translocated effector SseJ, indicating that lack of assembly of the translocon explains the spiC mutant phenotype.

J Cell Sci, 2002 Sep 15, 115(Pt 18), 3693 - 701
Diverting intracellular trafficking of Salmonella to the lysosome through activation of the late endocytic Rab7 by intracellular delivery of muramyl dipeptide; Mukherjee K et al.; Previously, we showed that live Salmonella-containing phagosomes (LSP) recruit early acting Rab5 and promote fusion with early endosomes, thus avoiding transport to the lysosomes . Therefore, live Salmonella survive in a specialized compartment . Here we show that scavenger-receptor-mediated intracellular delivery of muramyl dipeptide (MDP) to macrophages leads to efficient killing of Salmonella both in vitro and in vivo . To understand the intracellular trafficking modulation of Salmonella by delivery of MDP, we investigated the levels of endocytic Rab proteins, which are the major regulators of vesicular transport . Western blot analysis reveals reduced Rab5 and enhanced Rab7 content in the maleylated bovine serum albumin-MDP (MBSA-MDP)-treated cells . The reduced content of Rab5 in the treated cells and on phagosomes inhibits the fusion of Salmonella-containing phagosomes with early endosomes, and the enhanced Rab7 content in these cells facilitated targeting of LSP to lysosomes, which contain cathepsin D and vacuolar ATPase, for killing . In vitro reconstitution of lysosomal transport demonstrated that a reduced content of Rab5 and an enhanced level of Rab7 in MBSA-MDP-treated cells is primarily responsible for targeting Salmonella to lysosomes . Intracellular delivery of MDP thus offers a general strategy against macrophage-associated infections caused by intracellular pathogens that survive in the host cell by resisting transport to lysosomes.

Infect Immun, 2002 Sep, 70(9), 5319 - 21
Identification of genes affecting Salmonella enterica serovar enteritidis infection of chicken macrophages; Zhao Y et al.; Screening of 7,680 Salmonella enterica serovar Enteritidis mutants for attenuation in a chicken macrophage infection model yielded a series of mutants including several with defects in previously unrecognized Salmonella virulence genes . One of the newly identified genes was the pbpA2 gene, belonging to the penicillin binding protein gene family.

Infect Immun, 2002 Sep, 70(9), 5312 - 5
Salmonella enterica serovar Typhimurium periplasmic superoxide dismutases SodCI and SodCII are required for protection against the phagocyte oxidative burst; Sly LM et al.; Vitamin D(3) (1,25-dihydroxycholecalciferol) induced the phagocyte oxidative burst and intracellular killing of Salmonella enterica serovar Typhimurium in a phosphatidylinositol 3-kinase-dependent manner . The antimicrobial effect was more pronounced for Salmonella SodCI and SodCII mutants, confirming the role of the phagocyte oxidase in the vitamin D(3) effect . The results for an in vitro system with human THP-1 cells correlate with in vivo virulence data for mice and show that both the SodCI and SodCII enzymes are required to protect against the oxidative burst.

Infect Immun, 2002 Sep, 70(9), 5202 - 7
Hydrogen peroxide-mediated killing of Caenorhabditis elegans by Streptococcus pyogenes; Jansen WT et al.; Caenorhabditis elegans is currently introduced as a new, facile, and cheap model organism to study the pathogenesis of gram-negative bacteria such as Pseudomonas aeruginosa and Salmonella enterica serovar Typhimurium . The mechanisms of killing involve either diffusible exotoxins or infection-like processes . Recently, it was shown that also some gram-positive bacteria kill C . elegans, although the precise mechanisms of killing remained open . We examined C . elegans as a pathogenesis model for the gram-positive bacterium Streptococcus pyogenes, a major human pathogen capable of causing a wide spectrum of diseases . We demonstrate that S . pyogenes kills C . elegans, both on solid and in liquid medium . Unlike P . aeruginosa and S . enterica serovar Typhimurium, the killing by S . pyogenes is solely mediated by hydrogen peroxide . Killing required live streptococci; the killing capacity depends on the amount of hydrogen peroxide produced, and killing can be inhibited by catalase . Major exotoxins of S . pyogenes are not involved in the killing process as confirmed by using specific toxin inhibitors and knockout mutants . Moreover, no accumulation of S . pyogenes in C . elegans is observed, which excludes the involvement of infection-like processes . Preliminary results show that S . pneumoniae can also kill C . elegans by hydrogen peroxide production . Hydrogen peroxide-mediated killing might represent a common mechanism by which gram-positive, catalase-negative pathogens kill C . elegans.

Infect Immun, 2002 Sep, 70(9), 5096 - 106
Attenuated Salmonella enterica serovar Typhi expressing urease effectively immunizes mice against Helicobacter pylori challenge as part of a heterologous mucosal priming-parenteral boosting vaccination regimen; Londono-Arcila P et al.; Recombinant vaccine strains of Salmonella enterica serovar Typhi capable of expressing Helicobacter pylori urease were generated by transforming strains CVD908 and CVD908-htrA with a plasmid harboring the ureAB genes under the control of an in vivo-inducible promoter . The plasmid did not interfere with the ability of either strain to replicate and persist in human monocytic cells or with their transient colonization of mouse lungs . When administered to mice intranasally, both recombinant strains elicited antiurease immune responses skewed towards a Th1 phenotype . Vaccinated mice exhibited strong immunoglobulin G2a (IgG2a)-biased antiurease antibody responses as well as splenocyte populations capable of proliferation and gamma interferon (IFNgamma) secretion in response to urease stimulation . Boosting of mice with subcutaneous injection of urease plus alum enhanced immune responses and led them to a more balanced Th1/Th2 phenotype . Following parenteral boost, IgG1 and IgG2a antiurease antibody titers were raised significantly, and strong urease-specific splenocyte proliferative responses, accompanied by IFNgamma as well as interleukin-4 (IL-4), IL-5, and IL-10 secretion, were detected . Neither immunization with urease-expressing S . enterica serovar Typhi alone nor immunization with urease plus alum alone conferred protection against challenge with a mouse-adapted strain of H . pylori; however, a vaccination protocol combining both immunization regimens was protective . This is the first report of effective vaccination against H . pylori with a combined mucosal prime-parenteral boost regimen in which serovar Typhi vaccine strains are used as antigen carriers . The significance of these findings with regard to development of a human vaccine against H . pylori and modulation of immune responses by heterologous prime-boost immunization regimens is discussed.

Infect Immun, 2002 Sep, 70(9), 5065 - 74
Cruzipain induces both mucosal and systemic protection against Trypanosoma cruzi in mice; Schnapp AR et al.; Cruzipain, the major cysteinyl proteinase of Trypanosoma cruzi, is expressed by all developmental forms and strains of the parasite and stimulates potent humoral and cellular immune responses during infection in both humans and mice . This information suggested that cruzipain could be used to develop an effective T . cruzi vaccine . To study whether cruzipain-specific T cells could inhibit T . cruzi intracellular replication, we generated cruzipain-reactive CD4(+) Th1 cell lines . These T cells produced large amounts of gamma interferon when cocultured with infected macrophages, resulting in NO production and decreased intracellular parasite replication . To study the protective effects in vivo of cruzipain-specific Th1 responses against systemic T . cruzi challenges, we immunized mice with recombinant cruzipain plus interleukin 12 (IL-12) and a neutralizing anti-IL-4 MAb . These immunized mice developed potent cruzipain-specific memory Th1 cell responses and were significantly protected against normally lethal systemic T . cruzi challenges . Although cruzipain-specific Th1 responses were associated with T . cruzi protective immunity in vitro and in vivo, adoptive transfer of cruzipain-specific Th1 cells alone did not protect BALB/c histocompatible mice, indicating that additional immune mechanisms are important for cruzipain-specific immunity . To study whether cruzipain could induce mucosal immune responses relevant for vaccine development, we prepared recombinant attenuated Salmonella enterica serovar Typhimurium vaccines expressing cruzipain . BALB/c mice immunized with salmonella expressing cruzipain were significantly protected against T . cruzi mucosal infection . Overall, these data indicate that cruzipain is an important T . cruzi vaccine candidate and that protective T . cruzi vaccines will need to induce more than CD4(+) Th1 cells alone.

Antimicrob Agents Chemother, 2002 Sep, 46(9), 2977 - 81
Characterization of a self-transferable plasmid from Salmonella enterica serotype typhimurium clinical isolates carrying two integron-borne gene cassettes together with virulence and drug resistance genes; Guerra B et al.; An unusual self-transferable virulence-resistance plasmid (pUO-StVR2) was found in nine multidrug-resistant (ACSSuT phenotype) Salmonella enterica serotype Typhimurium clinical isolates that were assigned to four different phage types and a single and distinctive XbaI pulsed-field gel electrophoresis profile . pUO-StVR2 is an IncFII plasmid of about 140 kb in length carrying the spvA, spvB, and spvC (Salmonella plasmid virulence) and rck (resistance to complement killing) genes . It also carries the oxa1/aadA1a (ampicillin resistance and streptomycin-spectinomycin resistance) gene cassette configuration located within a class 1 integron with qacEDelta1/sul1 (ammonium antiseptics resistance and sulfadiazine resistance); the transposon genes merA, tnpA, and tnpR (mercury resistance, transposase, and resolvase of Tn21, respectively); and the catA1 (chloramphenicol resistance) and tet(B) (tetracycline resistance) genes . The insertion of resistance genes into a Salmonella virulence plasmid constitutes a new and interesting example of plasmid evolution and presents a serious public health problem.

Antimicrob Agents Chemother, 2002 Sep, 46(9), 2821 - 8
Antibiotic resistance genes and Salmonella genomic island 1 in Salmonella enterica serovar Typhimurium isolated in Italy; Carattoli A et al.; Fifty-four epidemiologically unrelated multidrug-resistant Salmonella enterica serovar Typhimurium isolates, collected between 1992 and 2000 in Italy, were analyzed for the presence of integrons . Strains were also tested for Salmonella genomic island 1 (SGI1), carrying antibiotic resistance genes in DT104 strains . A complete SGI1 was found in the majority of the DT104 strains . Two DT104 strains, showing resistance to streptomycin-spectinomycin and sulfonamides, carried a partially deleted SGI1 lacking the flo(st), tetR, and tetA genes, conferring chloramphenicol-florfenicol and tetracycline resistance, and the integron harboring the pse-1 gene cassette, conferring ampicillin resistance . The presence of SGI1 was also observed in serovar Typhimurium strains belonging to other phage types, suggesting either the potential mobility of this genomic island or changes in the phage-related phenotype of DT104 strains.

Psychoneuroendocrinology, 2002 Oct, 27(7), 791 - 804
Potentiation of tumor metastasis in adulthood by neonatal endotoxin exposure: sex differences; Hodgson DM et al.; Previous research in rodents has demonstrated that neonatal exposure to bacterial endotoxin alters the hypothalamic-pituitary-adrenal (HPA) axis resulting in hypersecretion of corticosterone in response to stress in adulthood . Given the known interactions between glucocorticoids and the immune system we tested the hypothesis that such alterations may impact on immune outcomes . Male and female Fischer 344 neonate rats were treated with endotoxin (0.05 mg/kg lipopolysaccaride from Salmonella enteritidis) or vehicle on days 1, 3, 5 and 7 postpartum . In adulthood, animals were subjected to chronic stress and the effect on resistance to tumor colonization (Exp . 1), natural killer (NK) cell activity (Exp . 2), and HPA reactivity (Exp . 3) was assessed . Neonatal endotoxin treatment was found to significantly impair NK cell activity and decrease resistance to tumor colonization in male but not female rats (P<0.05) . Neonatal endotoxin exposure did not affect corticosterone responses to chronic stress in male or female rats, but the corticosterone response to acute stress was potentiated by endotoxin exposure, most notably in females . In conclusion, neonatal endotoxin exposure was found to be associated with a sexually differentiated impairment in tumor colonization and NK activity and long-term alterations in corticosterone responses to stress . The effect on tumor colonization and NK activity was not, however, critically mediated by corticosterone levels . These findings suggest that neonatal bacterial infections may have long-term health implications, specifically in terms of resistance to cancer spread in adulthood .

J Food Prot, 2002 Aug, 65(8), 1227 - 32
Application of nested polymerase chain reaction to detection of Salmonella in poultry environment; Liu T et al.; Isolation of Salmonella from environmental and processing-plant poultry samples requires the sampling of large numbers of areas within the poultry house or plant . Subsequently, the required number of samples necessitates a large volume of work for a microbiology laboratory, especially when the protocol requires the inclusion of a delayed secondary enrichment for the isolation of Salmonella . This study examined the use of the polymerase chain reaction (PCR) to identify those secondary enrichments containing Salmonella . The unique Salmonella virulence gene invA was chosen as the target for the development of a nested PCR because of its uniform distribution among Salmonella serotypes . The use of nested PCR primers increased the sensitivity of detection 100-fold, resulting in the detection of as few as four cells . There was a strong, statistically significant positive correlation between PCR and culture results as determined by chi-square (P < 0.001) and kappa (kappa = 0.915; excellent agreement) tests . Using PCR to screen primary enrichments for presumptive Salmonella contamination, we improved our efficiency at isolating Salmonella upon secondary enrichment by 20%, and no false negatives were observed . This method will not only validate the use of secondary enrichment procedures but also reduce costs and manpower required for the surveillance of Salmonella.

J Food Prot, 2002 Aug, 65(8), 1215 - 20
Inactivation of Escherichia coli O157:H7, Salmonella enterica serotype enteritidis, and Listeria monocytogenes on lettuce by hydrogen peroxide and lactic acid and by hydrogen peroxide with mild heat; Lin CM et al.; Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses . In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics . A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40 degrees C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22 degrees C for 5 min, and 2% H2O2 at 50 degrees C for 60 or 90 s . Control lettuce leaves were treated with deionized water under the same conditions . A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E . coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L . monocytogenes . However, the sensory characteristics of lettuce were compromised by these treatments . The treatment of lettuce leaves with 2% H2O2 at 50 degrees C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days . A < or = 4-log reduction of E . coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L . monocytogenes was obtained . There was no significant difference (P > 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times . Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner . Hence, the treatment of lettuce with 2% H2O2 at 50 degrees C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.

Neurosurgery, 2002 Jul, 51(1), 234 - 7; discussion 237-8
Endovascularly treated cerebral aneurysm using Guglielmi detachable coils acting as a nidus for brain abscess formation secondary to Salmonella bacteremia: case report; Kirollos RW et al.; OBJECTIVE AND IMPORTANCE: Intracranial infections related to the various foreign materials used to secure intracranial aneurysms are extremely rare . The lack of neoendothelium formation across the necks of aneurysms, which is particularly prone to occur when the sac is incompletely packed by Guglielmi detachable coils (GDC), results in the absence of isolation of the coils from the circulation . Colonization of GDCs, which act as a foreign-body nidus after hematogenous spread from infections with bacteremia, may result in localized intracranial infection . CLINICAL PRESENTATION: A 55-year-old woman developed meningitis and a brain abscess surrounding a giant aneurysm that was treated endovascularly with GDC 3 1/2 years earlier . Four weeks before she sought care, she experienced an infective illness with proven Salmonella bacteremia . Salmonella group D was isolated from cerebrospinal fluid . INTERVENTION: The patient was treated successfully with long-term cephalosporin therapy . Follow-up imaging studies revealed regression of the abscess . CONCLUSION: This case suggests that the GDC acted as a colonized foreign body, resulting in the surrounding abscess formation after infection with Salmonella bacteremia . Alternatively, the reaction of the surrounding tissue to the GDC was the predisposing factor and acted as the nidus for the abscess formation.

Mol Microbiol, 2002 Aug, 45(4), 1019 - 27
Conflicting needs for a Salmonella hypervirulence gene in host and non-host environments; Mouslim C et al.; The Gram-negative pathogen Salmonella enterica harbours a periplasmic D-Ala-D-Ala dipeptidase (termed PcgL), which confers the ability to grow on D-Ala-D-Ala as sole carbon source . We now demonstrate that inactivation of the pcgL gene renders Salmonella hypervirulent . This phenotype results from the accumulation of peptidoglycan-derived D-Ala-D-Ala in the pcgL mutant and not from an intrinsically faster growth rate . Synthetic D-Ala-D-Ala (but not L-Ala-L-Ala or D-Ala) increased the number of wild-type Salmonella in the liver and spleen of mice within 24 h of injection, suggesting that D-Ala-D-Ala interferes with some aspect of innate immunity . However, the pcgL mutant was unable to grow on D-Ala-D-Ala as sole carbon source and was defective for survival in nutrient-poor conditions . We identified clinical isolates lacking D-Ala-D-Ala dipeptidase activity and unable to grow on D-Ala-D-Ala because of inactivation of the pcgL gene . Our data suggest that genes (such as pcgL) that, when mutated make pathogens more virulent, may be retained because their contribution to pathogen fitness in non-host environments outweighs potential advantages of the hypervirulent vari-ant in the infected host.

Mol Microbiol, 2002 Aug, 45(4), 967 - 82
Molecular dissection of Salmonella FliH, a regulator of the ATPase FliI and the type III flagellar protein export pathway; Gonzalez-Pedrajo B et al.; FliH is a soluble component of the flagellar export apparatus that binds to the ATPase FliI, and negatively regulates its activity . The 235-amino-acid FliH dimerizes and interacts with FliI to form a hetero-trimeric (FliH)2FliI complex . In the present work, the importance of different regions of FliH was examined . A set of 24 scanning deletions of 10 amino acids was constructed over the entire FliH sequence, along with several combined deletions of 40 amino acids and truncations of both N- and C-termini . The mutant proteins were examined with respect to (i) complementation; (ii) dominance and multicopy effects; (iii) interaction with wild-type FliH; (iv) interaction with FliI; (v) inhibition of the ATPase activity of FliI; and (vi) interaction with the putative general chaperone FliJ . Analysis of the deletion mutants revealed a clear functional demarcation between the FliH N- and C-terminal regions . The 10-amino-acid deletions throughout most of the N-terminal half of the sequence complemented and were not dominant, whereas those throughout most of the C-terminal half did not complement and were dominant . FliI binding was disrupted by C-terminal deletions from residue 101 onwards, indicating that the C-terminal domain of FliH is essential for interaction with FliI . FliH dimerization was abolished by deletion of residues 101-140 in the centre of the sequence, as were complementation, dominance and interaction with FliI and FliJ . The importance of this region was confirmed by the fact that fragment FliHC2 (residues 99-235) interacted with FliH and FliI, whereas fragment FliHC1 (residues 119-235) did not . FliHC2 formed a relatively unstable complex with FliI and showed biphasic regulation of ATPase activity, suggesting that the FliH N-terminus stabilizes the (FliH)2FliI complex . Several of the N-terminal deletions tested permitted close to normal ATPase activity of FliI . Deletion of the last five residues of FliH caused a fivefold activation of ATPase activity, suggesting that this region of FliH governs a switch between repression and activation of FliI . Deletion of the first 10 residues of FliH abolished complementation, severely reduced its interaction with FliJ and uncoupled its role as a FliI repressor from its other export functions . Based on these data, a model is presented for the domain construction and function of FliH in complex with FliI and FliJ.

Vet Rec, 2002 Jul 27, 151(4), 110 - 6
Risk-based evaluation of postmortem inspection procedures for pigs in Australia; Hamilton DR et al.; The results of traditional (incision) and risk-based (visual) postmortem inspection procedures were compared on groups of approximately 30,000 pigs . The performance characteristics used as a basis for comparison included the non-detection rates of grossly detectable abnormalities, the microbiological contamination rates of carcases and boned product, the association of reactive lymph nodes with carcase condemnation and the achievement of 'finished product standards' for 'wholesomeness' . It was estimated that 6 per cent of all cases of abscessation and 28 per cent of all cases of arthritis were undetected by the traditional method, and the comparable figures for the risk-based procedure were 19 per cent and 39 per cent . However, when the rates of contamination of undetected abnormalities with foodborne hazards and other carcase contamination parameters were taken into account, it was concluded that both inspection systems were likely to result in a very similar level of consumer protection . Any increase in potential exposure to foodborne hazards in the abnormalities undetected by risk-based inspection would be insignificant in comparison with the potential exposure to foodborne hazards resulting from contaminated 'normal' lymph nodes and carcase surfaces . There were no statistically significant differences between the two procedures in the contamination rates of pre-chill carcases or boned retail products with Salmonella and Yersinia species.

Curr Microbiol, 2002 Sep, 45(3), 226 - 9
In vitro inhibition of Salmonella enterica serovars choleraesuis and typhimurium, Escherichia coli F-18, and Escherichia coli O157:H7 by a porcine continuous-flow competitive exclusion culture; Harvey RB et al.; A competitive exclusion (CE) culture of porcine cecal bacteria was developed as a continuous-flow culture in chemostats, was designated RPCF, and was used as a model to determine its usefulness against in vitro colonization by Salmonella enterica serovars Typhimurium and Choleraesuis, Escherichia coli strain F-18, and E . coli serotype O157:H7 (933) . Chemostats with or without RPCF were inoculated with 10(6) colony-forming units (CFU)/ml of Typhimurium, Choleraesuis, F-18, or O157:H7 . Chemostats were sampled for salmonellae and E . coli at 15 min, 7 h, and every 24 h thereafter . In control chemostats without RPCF, Typhimurium, Choleraesuis, F-18, and O157:H7 rapidly established colonization and had concentrations of 10(6) CFU/ml for 96-120 h post-inoculation . In the chemostats that contained RPCF, reductions (P < 0.05) of Choleraesuis, F-18, and O157:H7 were observed at 24 h post-inoculation . Typhimurium was decreased (P < 0.05) at 48 h post-inoculation, and by 120 h post-inoculation, all chemostats were negative for the four challenge microorganisms . These results demonstrate that RPCF cultures were able to inhibit the growth of Typhimurium, Choleraesuis, and E . coli strains F-18 and O157:H7 in vitro and suggest the potential for the use of CE in swine to prevent disease induced by these microorganisms.

Proc Natl Acad Sci U S A, 2002 Aug 20, 99(17), 11260 - 4 Epub 2002 Aug 12.
MHC heterozygosity confers a selective advantage against multiple-strain infections; Penn DJ et al.; Genetic heterozygosity is thought to enhance resistance of hosts to infectious diseases, but few tests of this idea exist . In particular, heterozygosity at the MHC, the highly polymorphic loci that control immunological recognition of pathogens, is suspected to confer a selective advantage by enhancing resistance to infectious diseases (the "heterozygote advantage" hypothesis) . To test this hypothesis, we released mice into large population enclosures and challenged them with multiple strains of Salmonella and one of Listeria . We found that during Salmonella infections with three avirulent strains, MHC heterozygotes had greater survival and weight than homozygotes (unlike sham controls), and they were more likely to clear chronic Salmonella infection than homozygotes . In laboratory experiments, we found that MHC heterozygosity enhanced the clearance of multiple-strain Salmonella infections . Yet, contrary to what is widely assumed, the benefits of heterozygosity were due to resistance being dominant rather than overdominant, i.e., heterozygotes were more resistant than the average of parental homozygotes, but they were not more resistant than both . The fact that MHC heterozygotes were more resistant to infection and had higher fitness than homozygotes provides a functional explanation for MHC-disassortative mating preferences.

Food Chem Toxicol, 2002 Nov, 40(11), 1603 - 10
Genotoxicity of gardenia yellow and its components; Ozaki A et al.; Gardenia fruit (Gardenia jasminoides ELLIS) is widely used as a natural food colorant and as a traditional Chinese medicine for treatment of hepatic and inflammatory diseases . "Gardenia yellow" is a natural food colorant which is extracted by ethanol from gardenia fruit . The purpose of this study was to evaluate the genotoxicity of gardenia yellow . Genotoxicity of gardenia yellow and its components, crocetin, gentiobiose (a component of crocin), geniposide and genipin (formed by hydrolysis of geniposide), was studied by Ames test, rec-assay, and sister chromatid exchange (SCE) using V79 cells . Gardenia yellow and its components were found not to be mutagenic in the Salmonella reverse mutation assay . Gardenia yellow and genipin caused damage of DNA in rec-assay . Gardenia yellow induced a significant dose-dependent increase of SCE frequency (8.6 times at 1000 microg/ml as the value for the solvent control) . Only genipin induced SCEs significantly among the components of gardenia yellow . Moreover, genipin induced a significant increase of tetraploids at all doses tested (95% at 8 microg/ml) . Gardenia yellow preparation was analyzed by capillary electrophoresis (CE), and geniposide was detected . However, genipin was not observed . In conclusion, we have shown that genipin possesses genotoxicity . Furthermore, there were unidentified genotoxicants in gardenia yellow.

Berl Munch Tierarztl Wochenschr, 2002 Jul-Aug, 115(7-8), 252 - 8
{Report on Salmonella isolates submitted to the German National Veterinary Salmonella Reference Laboratory in the year 1999}; Dorn C et al.; The National Salmonella Reference Laboratory (NRL-Salm) of the Federal Institute for Health Protection of Consumers and Veterinary Medicine receives putative Salmonella isolates originating from animals, food, feed and the environment for typing . This report summarises the results of the sero- and phagetyping studies . In livestock S . Typhimurium DT 104 with 24% and S . Enteritidis PT 4 with 9% of all isolations predominate like in the human isolates . These sero- and phagetypes are frequently isolated from food as well and consequently can reach the consumer via the food chain.

AIDS, 2002 Aug 16, 16(12), 1633 - 41
Non-typhoidal salmonella bacteraemia among HIV-infected Malawian adults: high mortality and frequent recrudescence; Gordon MA et al.; OBJECTIVE: Non-typhoidal salmonella (NTS) bacteraemia is a common, recurrent illness in HIV-infected African adults . We aimed to describe the presentation and outcome of NTS bacteraemia, the pattern of recurrence, and to determine whether recurrence results from re-infection or recrudescence . DESIGN: One hundred consecutive adult inpatients with NTS bacteraemia in Blantyre, Malawi, were treated with chloramphenicol . Survivors were prospectively followed to detect bacteraemic recurrence . METHODS: Index and recurrent isolates were typed by antibiogram, pulsed-field gel electrophoresis and plasmid analysis to distinguish recrudescence from re-infection . RESULTS: Inpatient mortality was 47%, and 1-year mortality was 77% . A total of 77 out of 78 cases were HIV positive . Anaemia was associated with inpatient death, and several features of AIDS were associated with poor outpatient survival . Among survivors, 43% (19/44) had a first recurrence of NTS bacteraemia at 23-186 days . Among these, 26% (5/19) developed multiple recurrences up to 245 days . No recurrence was seen after 245 days, despite follow-up for up to 609 days (median 214) . Suppurative infections were not found at presentation, and were only seen twice at recurrence . Index and recurrent paired isolates were identical by phenotyping and genotyping, consistent with recrudescence, rather than re-infection . CONCLUSION: NTS bacteraemia has a high mortality (47%) and recurrence (43%) rate in HIV-infected African adults . Recurrence is caused by recrudescence rather than re-infection . As focal infections were rarely found, recrudescence may often be a consequence of intracellular tissue sequestration . There is an urgent need for improved primary treatment and secondary prophylaxis in Africa.

Am J Vet Res, 2002 Aug, 63(8), 1145 - 50
Hematologic and serum biochemical changes in Salmonella ser Typhimurium-infected calves; Santos RL et al.; OBJECTIVE: To evaluate hematologic and serum biochemical changes in Salmonella ser Typhimurium-infected calves . ANIMALS: 16 male 3- to 4-week-old dairy calves . PROCEDURE: 13 calves were experimentally infected with S Typhimurium (strains IR715 and CS401, which are derivatives of ATCC 14028), and 3 calves were uninfected controls . Several hematologic and serum biochemical parameters were measured . RESULTS: Hematologic changes included increases in PCV, RBC count, and hemoglobin concentration, associated with a transitory leukopenia characterized by neutropenia and lymphopenia . Biochemical findings included hypoglycemia, increased BUN, creatinine, and fibrinogen concentrations, and decreased sodium, total CO2, calcium, total protein, and albumin concentrations . Increased total bilirubin concentration associated with decreased conjugated bilirubin concentration was also observed . No significant changes in aspartate aminotransferase, gamma-glutamyltranspeptidase, alkaline phosphatase, and creatinine kinase activities were detected . CONCLUSIONS AND CLINICAL RELEVANCE: Experimental salmonellosis of calves results in marked to severe dehydration, accompanied by metabolic acidosis, hypoglycemia, and an acute inflammatory response associated with increased fibrinogen concentrations and severe neutropenia immediately after inoculation.

J Bacteriol, 2002 Sep, 184(17), 4699 - 708
Salmonella type III secretion-associated protein InvE controls translocation of effector proteins into host cells; Kubori T et al.; Salmonella enterica encodes a type III secretion system (TTSS) within a pathogenicity island located at centisome 63 (SPI-1), which is essential for its pathogenicity . This system mediates the transfer of a battery of bacterial proteins into the host cell with the capacity to modulate cellular functions . The transfer process is dependent on the function of protein translocases SipB, SipC, and SipD . We report here that Salmonella protein InvE, which is also encoded within SPI-1, is essential for the translocation of bacterial proteins into host cells . An S . enterica serovar Typhimurium mutant carrying a loss-of-function mutation in invE shows reduced secretion of SipB, SipC, and SipD while exhibiting increased secretion of other TTSS effector proteins . We also demonstrate that InvE interacts with a protein complex formed by SipB, SipC, and their cognate chaperone, SicA . We propose that InvE controls protein translocation by regulating the function of the Sip protein translocases.

Commun Dis Public Health, 2002 Jun, 5(2), 101 - 5
General outbreaks of infectious intestinal disease linked with salad vegetables and fruit, England and Wales, 1992-2000; Long SM et al.; Between 1992 and 2000, 1,518 foodborne general outbreaks of infectious intestinal disease (IID) were reported to the Public Health Laboratory Service (PHLS) Communicable Disease Surveillance Centre (CDSC), of which 83 (5.5%) were associated with the consumption of salad vegetables or fruit (SVF) . The pathogens most frequently reported were salmonellas (41.0%) and Norwalk-like virus (NLV) (15.7%) . In total 3,438 people were affected; 69 were admitted to hospital and one person died . Most outbreaks were linked to commercial catering premises (67.5%) . Three community outbreaks, of Salmonella enterica serovar Typhimurium Definitive Phage Type (DT) 104, S . Typhimurium DT 204b and Shigella sonnei infection, were found to be associated with lettuce contaminated at source, and these accounted for 501 (14.6%) cases . The latter two outbreaks were international, involving several European countries . This demonstrates how contamination of SVF during production/processing can result in major, geographically widespread, outbreaks of infection with serious public health consequences.

J Mol Evol, 2002 Jul, 55(1), 37 - 51
Characterization of the ysa pathogenicity locus in the chromosome of Yersinia enterocolitica and phylogeny analysis of type III secretion systems; Foultier B et al.; Several Gram negative bacteria use a complex system called "type III secretion system" (TTSS) to engage their host . The archetype of TTSS is the plasmid-encoded "Yop virulon" shared by the three species of pathogenic Yersinia (Y . pestis, Y . pseudotuberculosis, and Y . enterocolitica) . A second TTSS, called Ysa (for Yersinia secretion apparatus) was recently described in Y . enterocolitica 8081, a strain from serotype O:8 . In this study, we describe the ysa locus from A127/90, another strain of serotype O:8, and we extend the sequence to several new genes encoding Ysp proteins which are the substrates of this secretion system, and a putative chaperone SycB . According to the deduced protein sequences, the ysa system from A127/90 is identical to that of 8081 . It is different from the chromosome-encoded TTSS of Y . pestis but is instead closely related to the Mxi-Spa TTSS of Shigella and to the SPI-1 encoded TTSS of Salmonella enterica . We further demonstrated that the ysa locus is only present in biotype IB strains of Y . enterocolitica . Including this new Ysa system, a phylogenetic analysis of the 26 known TTSSs was carried out, based on the sequence analysis of three conserved proteins . All the TTSSs fall into five different clusters . The phylogenetic tree of these TTSSs is completely different from the evolutionary tree based on 16S RNA, indicating that TTSSs have been distributed by horizontal transfer.

Rev Gastroenterol Peru, 1996 Sep-Dec, 16(3), 214 - 21
{Enteropathogenic agents isolated in persistent diarrhoea}; Lopez Marin D et al.; Out of 45558 patients admited in our hospital, from January 1990 to December 1993, the clinical records of 4445 children with diarrhoea (4289 with acute diarrihoea and 156 with persistent diarrhoea) were reviewed . Those with positive bacteriological or parasitological results were taken as sample.Salmonella was the bacteria most frequently isolated in both groups of patients . ECEP and ECEH had a similar distribution while Shigella showed a higher frequency in cases of persistent diarrhoea, for a third pace of incidence.From the parasitological point of view, Cryptosporidium and Giardia had the same behavior.

J Immunol, 2002 Aug 15, 169(4), 2196 - 203
Characterization of CD8(+) effector T cell responses in volunteers immunized with Salmonella enterica serovar Typhi strain Ty21a typhoid vaccine; Salerno-Goncalves R et al.; Salmonella enterica serovar Typhi (S . typhi) strain Ty21a remains the only licensed attenuated typhoid vaccine . Despite years of research, the identity of the protective immunological mechanisms elicited by immunization with the Ty21a typhoid vaccine remains elusive . The present study was designed to characterize effector T cell responses in volunteers immunized with S . typhi strain Ty21a typhoid vaccine . We determined whether immunization with Ty21a induced specific CTL able to lyse S . typhi-infected cells and secrete IFN-gamma, a key effector molecule against intracellular pathogens . We measured the functional activity of these CTL by a (51)Cr-release assay using 8-day restimulated PBMC from Ty21a vaccinees as effector cells and S . Typhi-infected autologous PHA-activated PBMC as target cells . Most vaccinees exhibited consistently increased CD8-mediated lysis of targets by postimmunization PBMC when compared with preimmunization levels . We also developed an IFN-gamma ELISPOT assay to quantify the frequency of IFN-gamma spot-forming cells (SFC) in PBMC from Ty21a vaccinees using an ex vivo system . Significant increases in the frequency of IFN-gamma SFC following immunization (mean +/- SD, 393 +/- 172; range 185-548 SFC/10(6) PBMC; p = 0.010), as compared with preimmunization levels, were observed . IFN-gamma was secreted predominantly by CD8(+) T cells . A strong correlation was recorded between the cytolytic activity of CTL lines and the frequency of IFN-gamma SFC (r(2) = 0.910, p < 0.001) . In conclusion, this work constitutes the first evidence that immunization of volunteers with Ty21a elicits specific CD8(+) CTL and provides an estimate of the frequency of CD8(+) IFN-gamma-secreting cells induced by vaccination.

Am J Trop Med Hyg, 2002 Apr, 66(4), 416 - 21
Simple dipstick assay for the detection of Salmonella typhi-specific IgM antibodies and the evolution of the immune response in patients with typhoid fever; Hatta M et al.; Application of a dipstick assay for the detection of Salmonella typhi-specific IgM antibodies on samples collected from S . typhi or S . paratyphi culture-positive patients at the day of admission to the hospital revealed the presence of specific IgM antibodies in 43.5%, 92.9%, and 100% for samples collected 4-6 days, 6-9 days, and > 9 days after the onset of fever, respectively . The mean sensitivity for samples collected an average of 6.6 days after the onset of fever was 65.3% . Culture was positive in 65.9% of the cases with a final clinical diagnosis of typhoid fever . Testing of paired serum samples from culture negative patients with a final clinical diagnosis of typhoid fever resulted in staining of the dipstick in 4.3% of the samples collected at the day of admission to the hospital and in 76.6% of the samples collected one week later, thereby provided strong supporting evidence of typhoid fever by demonstrating seroconversion in a large proportion of the patients . The dipstick assay may thus also be useful for the serodiagnosis of culture-negative patients with clinical signs and symptoms consistent with typhoid fever . The advantages of the dipstick assay are that the result can be obtained on the same day allowing a prompt treatment, that only a small volume of serum is needed, and that no special laboratory equipment is needed to perform the assay . The stability of the reagents of the dipstick and the simplicity of the assay allows its use in places that lack laboratory facilities.

Biosci Biotechnol Biochem, 2002 Jun, 66(6), 1400 - 2
Antimutagenic effect of amino acids on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG); Roy MK et al.; The antimutagenic activity of protein-constituting amino acids except histidine on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in vitro using Salmonella typhinurium TA-100 as an indicator bacterium (Ames test), and concentrations (IC50) of amino acids that inhibit 50% of the mutagenecity were measured . Cysteine was found to be most active and glycine, tryptophan, lysine, and arginine were strong antimutagenic amino acids . Other amino acids showed moderate or weak antimutagenic activities, depending on the amino acids . The results indicate that amino acids play a substantial role in chemoprevention of N-nitroso amine-induced mutagenicity.

Mutat Res, 2002 Aug 26, 519(1-2), 205 - 9
Mutagenicity of emissions from a natural gas fueled truck; Lapin CA et al.; Concern about the potential health risks of particulate exhaust emissions from diesel-fueled vehicles has led regulatory agencies to foster the use of natural gas fueled heavy duty vehicles . However, the potential health risks of particulate exhaust emissions from natural gas fueled vehicles have not been well-studied . The present study investigated the mutagenicity of particulate exhaust emissions from a natural gas fueled refuse truck currently in-service . Organic solvent extracts of exhaust particulate emissions from the natural gas fueled truck were positive in both Salmonella tester strains TA98 and TA100 in the presence and absence of S-9 . The maximum mutagenic responses ranged from 7-fold in the TA100 strain to 87-fold in the TA98 strain when compared to negative controls . Our results show that current in-service natural gas fueled heavy duty trucks have particulate exhaust emissions that possess mutagenic activity . This finding requires follow-up studies to develop a database on natural gas fueled vehicles for comparison with data on diesel-fueled vehicles to aid in making decisions on use of alternative fuels to reduce air pollution health risks.

Mutat Res, 2002 Aug 26, 519(1-2), 67 - 74
Comparison of the Ames test and a newly developed assay for detection of mutagenic pollution of marine environments; Czyz A et al.; A new assay for detection of mutagenic pollution of marine environments, based on the use of a series of genetically modified Vibrio harveyi strains, was developed recently . Here, we compared this assay with a commonly used Ames test, employing mutants of Salmonella enterica serovar Typhimurium . We found that survival of S . enterica serovar Typhimurium in artificial marine water and in different samples of marine water is dramatically reduced relative to that of V . harveyi strains . This indicates that V . harveyi strains are significantly more useful in testing samples of marine water . Moreover, sensitivity of both assays was compared . We found that using the V . harveyi assay it is possible to detect significantly (from a few to several times) lower concentrations of typical chemical mutagens than employing the Ames test . Although the higher sensitivity of the V . harveyi test relative to the Ames assay may be of minor importance when testing mutagenicity of certain chemicals in their pure form under laboratory conditions, this feature is very important in testing samples of marine water . Therefore, we assume that the V . harveyi assay may be an adequate test for detection of mutagenic pollution of marine environments.

Res Microbiol, 2002 Jun, 153(5), 281 - 7
Role of trehalose biosynthesis in environmental survival and virulence of Salmonella enterica serovar typhimurium; Howells AM et al.; The otsA and otsB genes, encoding trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase respectively, have been isolated from Salmonella enterica serovar typhimurium and nucleotide-sequenced . Induction of trehalose biosynthesis by exposure of bacteria to high osmotic strength resulted in the intracellular accumulation of trehalose . An otsA mutant of S . enterica serovar typhimurium was more susceptible to killing by heat, and grew poorly under conditions of high osmolarity . The wild-type and otsA mutant strains showed similar abilities to colonise spleen tissues after oral dosing of mice . These findings suggest that the otsBA gene products play a role in environmental survival, but not in virulence, of S . enterica serovar typhimurium.

Int J Food Microbiol, 2002 Aug 25, 77(3), 223 - 31
Survival of Escherichia coli O157:H7 and Salmonella Muenchen on apples as affected by application of commercial fruit waxes; Kenney SJ et al.; Survival of Escherichia coli O157:H7, Salmonella Muenchen, and yeasts and molds on apples as affected by application of five commercial apple waxes was investigated . Red Delicious cv . apples at 21 degrees C were spot inoculated with E . coli O157:H7 and S . Muenchen and spray coated with waxes . Apples sprayed with water served as controls . Apples were dried at either 21 or 55 degrees C for 2 min before subjecting to microbiological analysis after storage for 0, 1, 3, 6, and 12 weeks at 2 or 21 degrees C . Drying temperature did not significantly influence populations of E . coli O157:H7 and S . Muenchen . Waxing reduced populations E . coli O157:H7 and S . Muenchen by up to 1.48 log10 cfu/apple . Compared to untreated apples, treatment of apples with water or waxes resulted in significant (P < or = 0.05) reductions in populations of E . coli O157:H7 and S . Muenchen during storage at 2 degrees C . Reductions on waxed apples stored at 21 degrees C were not as marked compared to reductions on waxed apples stored at 2 degrees C . With the exception of one wax, drying temperature did not significantly influence populations of yeasts and molds . Mold populations were less affected by wax applications than were yeasts, and were detected in higher numbers on apples treated with three of the five waxes compared to populations recovered from untreated control apples . None of the waxes evaluated can be relied upon to kill or remove E . coli O157:H7 and Salmonella on apples.

Int J Food Microbiol, 2002 Aug 25, 77(3), 199 - 204
Bacteriological analysis of fresh produce in Norway; Johannessen GS et al.; A total of 890 samples of fresh produce obtained from Norwegian markets were examined in order to assess the bacteriological quality of the products and their potential public health risk . The samples comprised lettuce, pre-cut salads, growing herbs, parsley and dill, mushrooms and strawberries . The samples were analysed for the presence of thermotolerant coliform bacteria (TCB), Escherichia coli O157, Salmonella spp., Listeria monocytogenes, Staphylococcus spp., and Yersinia enterocolitica . Neither Salmonella spp . nor E . coli O157 were isolated . For all product groups included, TCB were isolated from a small proportion of samples . Three samples harboured L . monocytogenes; one of the isolates belonging to serogroup 1 (champignons) and two of the isolates belonging to serogroup 4 (Chinese leaves and strawberries) . Staphylococci were isolated from a relatively large proportion of the samples of strawberries and mushrooms . However, only four isolates were identified as S . aureus (non-toxinogenic) . By the use of PCR, the presence of Y . enterocolitica was indicated in a few of the samples of lettuce, whilst no positive samples were found using a culturing method . The study shows that the occurrence of pathogenic bacteria and TCB in the products analysed was quite low . Nevertheless, the results indicate that the type of products analysed may contain pathogenic bacteria and thereby represent a risk to the consumers in regard to food-borne diseases.

Plasmid, 2002 May, 47(3), 159 - 71
Characterisation and distribution of a cryptic Salmonella typhi plasmid pHCM2; Kidgell C et al.; pHCM2 is a 106 kbp cryptic plasmid harboured by Salmonella typhi CT18, originally isolated from a typhoid patient in Vietnam . The genome of S . typhi CT18, including pHCM2, has recently been completely sequenced and annotated . Bioinformatic analysis revealed that 57% of the coding sequences (CDSs) encoded on pHCM2 display over 97% DNA sequence identity to the virulence-associated plasmid of Yersinia pestis, pFra . pHCM2 encodes no obvious virulence-associated determinants or antibiotic resistance genes but does encode a wide array of putative genes directly related to DNA metabolism and replication . PCR analysis of a series of S . typhi isolates from Vietnam detected pHCM2-related DNA sequences in some S . typhi isolated before, but not after, 1994 . Similar pHCM2-related sequences were also detected in S . typhi isolated from other regions of South East Asia and Pakistan but not elsewhere in the world.

J Clin Microbiol, 2002 Aug, 40(8), 3050 - 2
Real-time PCR detection of salmonella in suspect foods from a gastroenteritis outbreak in kerr county, Texas; Daum LT et al.; In June 2001, an outbreak of acute gastroenteritis among 109 attendees of a church picnic in Kerr County, Texas, was reported . A 5'-nuclease PCR assay was used to screen for Salmonella in nine food items from the buffet line . Barbeque chicken B tested positive for Salmonella, and no amplification was detected in the remaining food items . These PCR findings were consistent with culture results and were confirmed by direct nucleotide sequencing . Salmonella enterica serotype Panama was cultured from both food and patient stool samples.

J Clin Microbiol, 2002 Aug, 40(8), 2999 - 3003
Comparison of CHROMagar Salmonella medium and xylose-lysine-desoxycholate and Salmonella-Shigella agars for isolation of Salmonella strains from stool samples; Maddocks S et al.; The growth and appearance of 115 stock Salmonella isolates on a new formulation of CHROMagar Salmonella (CAS) medium were compared to those on xylose-lysine-desoxycholate agar (XLD), Salmonella-Shigella agar (SS), and Hektoen enteric agar (HEA) media . CAS medium was then compared prospectively to XLD and SS for the detection and presumptive identification of Salmonella strains in 500 consecutive clinical stool samples . All stock Salmonella isolates produced typical mauve colonies on CAS medium . Nine Salmonella strains were isolated from clinical specimens . The sensitivities for the detection of salmonellae after primary plating on CAS medium and the combination of XLD and SS after enrichment were 100% . The specificity for the detection of salmonellae after primary plating on CAS medium (83%) was significantly (P < 0.0001) higher than that after primary plating on the combination of SS and XLD media (55%) (a 28% difference in rates; 95% confidence interval, 23.0 to 34%) . Twenty-nine non-Salmonella organisms produced mauve colonies on CAS medium, including 17 Candida spp . (59%) and 8 Pseudomonas spp . (28%) . These were easily excluded as salmonellae by colony morphology, microscopic examination of a wet preparation, or oxidase testing . One biochemically inert Escherichia coli isolate required further identification to differentiate it from Salmonella spp . The use of plating on CAS medium demonstrated high levels of sensitivity and specificity and reduced the time to final identification of Salmonella spp., resulting in substantial cost savings . It can be recommended for use for the primary isolation of Salmonella spp . from stool specimens . Other media (e.g., XLD) are required to detect Shigella spp . concurrently.

J Clin Microbiol, 2002 Aug, 40(8), 2813 - 22
Molecular characterization of multidrug-resistant Salmonella enterica subsp . enterica serovar Typhimurium isolates from swine; Gebreyes WA et al.; As part of a longitudinal study of antimicrobial resistance among salmonellae isolated from swine, we studied 484 Salmonella enterica subsp . enterica serovar Typhimurium (including serovar Typhimurium var . Copenhagen) isolates . We found two common pentaresistant phenotypes . The first was resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (the AmCmStSuTe phenotype; 36.2% of all isolates), mainly of the definitive type 104 (DT104) phage type (180 of 187 isolates) . The second was resistance to ampicillin, kanamycin, streptomycin, sulfamethoxazole, and tetracycline (the AmKmStSuTe phenotype; 44.6% of all isolates), most commonly of the DT193 phage type (77 of 165 isolates), which represents an unusual resistance pattern for DT193 isolates . We analyzed 64 representative isolates by amplified fragment length polymorphism (AFLP) analysis, which revealed DNA fingerprint similarities that correlated with both resistance patterns and phage types . To investigate the genetic basis for resistance among DT193 isolates, we characterized three AmKmStSuTe pentaresistant strains and one hexaresistant strain, which also expressed resistance to gentamicin (Gm phenotype), all of which had similar DNA fingerprints and all of which were collected during the same sampling . We found that the genes encoding the pentaresistance pattern were different from those from isolates of the DT104 phage type . We also found that all strains encoded all of their resistance genes on plasmids, unlike the chromosomally encoded genes of DT104 isolates, which could be transferred to Escherichia coli via conjugation, but that the plasmid compositions varied among the isolates . Two strains (strains UT08 and UT12) had a single, identical plasmid carrying bla(TEM) (which encodes ampicillin resistance), aphA1-Iab (which encodes kanamycin resistance), strA and strB (which encode streptomycin resistance), class B tetA (which encodes tetracycline resistance), and an unidentified sulfamethoxazole resistance allele . The third pentaresistant strain (strain UT20) was capable of transferring by conjugation two distinct resistance patterns, AmKmStSuTe and KmStSuTe, but the genes were carried on plasmids with slightly different restriction patterns (differing by a single band of 15 kb) . The hexaresistant strain (strain UT30) had the same plasmid as strains UT08 and UT12, but it also carried a second plasmid that conferred the AmKmStSuGm phenotype . The second plasmid harbored the gentamicin resistance methylase (grm), which has not previously been reported in food-borne pathogenic bacteria . It also carried the sul1 gene for sulfamethoxazole resistance and a 1-kb class I integron bearing aadA for streptomycin resistance . We also characterized isolates of the DT104 phage type . We found a number of isolates that expressed resistance only to streptomycin and sulfamethoxazole (the StSu phenotype; 8.3% of serovar Typhimurium var . Copenhagen strains) but that had AFLP DNA fingerprints similar or identical to those of strains with genes encoding the typical AmCmStSuTe pentaresistance phenotype of DT104 . These atypical StSu DT104 isolates were predominantly cultured from environmental samples and were found to carry only one class I integron of 1.0 kb, in contrast to the typical two integrons (InC and InD) of 1.0 and 1.2 kb, respectively, of the pentaresistant DT104 isolates . Our findings show the widespread existence of multidrug-resistant Salmonella strains and the diversity of multidrug resistance among epidemiologically related strains . The presence of resistance genes on conjugative plasmids and duplicate genes on multiple plasmids could have implications for the spread of resistance factors and for the stability of multidrug resistance among Salmonella serovar Typhimurium isolates.

J Clin Microbiol, 2002 Aug, 40(8), 2779 - 85
Phylogenetic analysis of Salmonella, Shigella, and Escherichia coli strains on the basis of the gyrB gene sequence; Fukushima M et al.; Phylogenetic analysis of about 200 strains of Salmonella, Shigella, and Escherichia coli was carried out using the nucleotide sequence of the gene for DNA gyrase B (gyrB), which was determined by directly sequencing PCR fragments . The results establish a new phylogenetic tree for the classification of Salmonella, Shigella, and Escherichia coli in which Salmonella forms a cluster separate from but closely related to Shigella and E . coli . In comparison with 16S rRNA analysis, the gyrB sequences indicated a greater evolutionary divergence for the bacteria . Thus, in screening for the presence of bacteria, the gyrB gene might be a useful tool for differentiating between closely related species of bacteria such as Shigella spp . and E . coli . At present, 16S rRNA sequence analysis is an accurate and rapid method for identifying most unknown bacteria to the genus level because the highly conserved 16S rRNA region is easy to amplify; however, analysis of the more variable gyrB sequence region can identify unknown bacteria to the species level . In summary, we have shown that gyrB sequence analysis is a useful alternative to 16S rRNA analysis for constructing the phylogenetic relationships of bacteria, in particular for the classification of closely related bacterial species.

Can J Vet Res, 2002 Jul, 66(3), 151 - 7
Improvements required for the detection of Salmonella Pullorum and Gallinarum; Proux K et al.; Detection of the specific Salmonella serovar Gallinarum, which is divided into the biovars Pullorum and Gallinarum, is compulsory under the national hygienic and sanitary control regulations of France for breeding flocks whose offspring are exported . Our aim was to examine the suitability of bacteriologic and serologic methods routinely used in France to screen serum samples and organs for S . Gallinarum . Since bacteriologic reference techniques are designed to isolate the commonly occurring non-typhoid serovars, such as S . Typhimurium, S . Enteritidis, and others that cause outbreaks of foodborne illness, they may not be particularly suitable for detecting S . Pullorum and S . Gallinarum . This hypothesis was confirmed by the inoculation of 10-wk-old chickens and 1-d-old chicks with various strains of S . Pullorum and S . Gallinarum . The most reliable enrichment media were selenite cystine and Rappaport-Vassiliadis broths . Moreover, on the usual plating media, colonies were small, grew more slowly than the common serovars (in 48 h instead of 24 h), and had an unusual appearance . Since the rapid slide agglutination (RSA) test is based only on antigens from standard and variant strains of S . Pullorum, it may not readily detect S . Gallinarum . In our study, it detected infection in all 10-wk-old chickens inoculated with S . Pullorum strains but did not detect any antibodies against S . Gallinarum . Therefore, S . Gallinarum antigens must be added to the S . Pullorum antigens used in the RSA test in order to detect antibodies produced by birds infected with either biovar.

Rev Med Chil, 2002 May, 130(5), 495 - 501
{Epidemiological situation of foodborne diseases in Santiago, Chile in 1999-2000}; Prado V et al.; BACKGROUND: Foodborne diseases are becoming an important cause of morbidity in Chile . In the Metropolitan Region of Chile, the Environmental Health Service started a surveillance program for foodborne diseases in 1994 . In 2000, this program was complemented with an etiologic study of individuals involved in outbreaks . AIM: To report the incidence of foodborne outbreaks in the Metropolitan Region of Chile and its causative agents . RESULTS: One hundred ninety outbreaks of foodborne diseases were reported in 1999 and 260 in 2000 . The Southern Metropolitan health service had the higher incidence rates (7.5 in 1999 and 8.2 in 2000) . The mean attack rates were 25% in both periods, affecting 1248 individuals in 1999 and 1774 in 2000 . In 18% of outbreaks, a pathogen was identified; the most frequent agents were Salmonella Spp, Staphylococcus aureus and Shigella . In 15% of subjects, the cause was histamine or chemical agents . In the rest of the cases, the cause was not identified . The foods with higher risk of causing foodborne diseases were hot prepared dishes, home made goat cheese and meats . CONCLUSIONS: The incidence rates of foodborne disease in Metropolitan Area of Chile are high and maybe underestimate, only in a low rate of outbreaks was possible to have samples for etiologic studies . For a better understanding of this problem, timely notification of foodborne diseases must be encouraged and educational campaigns about the proper manipulation of food items must be implemented.

Zh Mikrobiol Epidemiol Immunobiol, 2002 May-Jun, (3), 70 - 9
{Use of recombinant Salmonella strains for supplying the macro-organism with biologically active molecules}; Bondarenko VM et al.; The characterization of known Salmonella vaccine strains and different attenuated mutants used for developing new vaccines is presented . The use of attenuated Salmonella strains as vaccine vector for the supply of heterologous antigens opens prospects for the creation of effective and commonly available vaccines which approximate the "ideal" vaccine in their qualitative characteristics . The possibility of the genetic modification of attenuated strains permits their targeted reconstruction, considering the specific features of the formation of immune response to the definite heterologous antigen supplied to the body by the bacterial vector.

Zh Mikrobiol Epidemiol Immunobiol, 2002 May-Jun, (3), 63 - 5
{Biocenotic activity of salmonellae of rare groups}; Tabaeva AA et al.; The symbiotic activity of 69 Salmonella cultures of rare groups, belonging to the strains of different origin, with respect to pathogenic and nonpathogenic bacteria, bacilli, Staphylococcus aureus was studied . The study revealed that salmonellae of rare groups were capable of synergetic activity with respect to all test cultures used in this study . The spectrum and manifestation of this property were found to depend on the origin of the strains . The direction of the synergetic activity of salmonellae of rare groups, isolated from the environment, made it possible to suggest the importance of this sign for their survival under unfavorable environmental conditions . Close relationship between the synergetic activity of microorganisms and the clinical course of infection gave grounds for the conclusion on the pathogenic importance of this property and the necessity of its study in the evaluation of the pathogenic potential of microorganisms.

Mol Microbiol, 2002 Aug, 45(3), 711 - 9
Fe(III)-mediated cellular toxicity; Chamnongpol S et al.; Because it can undergo reversible changes in oxidation state, iron is an excellent biocatalyst but also a potentially deleterious metal . Iron-mediated toxicity has been ascribed to Fe(II), which reacts with oxygen to generate free radicals that damage macromolecules and cause cell death . However, we now report that Fe(III) exhibits microbicidal activity towards strains of Salmonella enterica, Escherichia coli and Klebsiella pneumoniae defective in the Fe(III)-responding PmrA/PmrB signal transduction system . Fe(III) bound to a pmrA Salmonella mutant more effectively than to the isogenic wild-type strain and exerted its microbicidal activity even under anaerobic conditions . Moreover, Fe(III) permeabilized the outer membrane of the pmrA mutant, rendering it susceptible to vancomycin, which is normally non-toxic to Gram-negative species . On the other hand, Fe(III) did not affect the viability of a mutant defective in Fur, the major regulator of cytosolic iron homeostasis, which is hypersensitive to Fe(II)-mediated toxicity . A functional pmrA gene was necessary for bacterial survival in soil . Our results indicate that Fe(III) exerts its microbicidal activity by a mechanism that is oxygen independent and different from that mediated by Fe(II).

Pediatr Int, 2002 Aug, 44(4), 391 - 3
Intrafamilial transmission of Salmonella oranienburg; Niizuma T et al.; BACKGROUND: There were diffuse outbreaks of Salmonella oranienburg in Japan since March 1999 which included 1505 patients . The outbreak was caused through ingestion of a dried squid snack contaminated with S . oranienburg . Such a large number of cases has not been previously recorded in Japan or other countries . METHODS: A 9-month-old boy was admitted to our hospital with enteritis and bacteremia due to S . oranienburg . His older brother had eaten the contaminated snack . We detected S . oranienburg in the stools of five out of his six family members . RESULTS: With the exception of the index case's brother, no other family members had eaten the contaminated snack . The S . oranienburg strain detected in the family was confirmed to be the same strain by pulse field gel electrophoresis . Therefore, we presumed there had been a series of household transmissions . CONCLUSION: Our observation of intrafamilial transmission suggests that S . oranienburg may be highly infectious.

Biochemistry (Mosc), 2002 Jul, 67(7), 747 - 52
Endotoxin-lipoprotein complex formation as a factor in atherogenesis: associations with hyperlipidemia and with lecithin:cholesterol acyltransferase activity; Schwartz YSh et al.; A potential role of endotoxin-lipoprotein (bacterial lipopolysaccharide-lipoprotein, LPS-LP) complex formation as a pathogenic factor for atherosclerosis has not been studied yet . The aim of this study was to test the hypothesis that in endotoxinemia in humans hyperlipidemia associated with atherosclerosis development can favor an excessive LPS-LP complex formation, and endotoxin presented in blood can inhibit lecithin:cholesterol acyltransferase (LCAT), one of the key enzymes of reverse cholesterol transport . Endotoxin-binding capacity of lipoproteins (LP) in patients with normolipidemia and hyperlipidemia types IIa and IV was estimated from label incorporation into different LP fractions isolated by means of sequential ultracentrifugation following serum preincubation with Salmonella minnesota R595 125I-labeled LPS . The effect of varied concentrations of S . minnesota R595 LPS on LCAT activity was evaluated from the overall esterifying activity of serum using {1,2-3H2}cholesterol-labeled substrate . The elevation of low density LP (LDL) and very low density LP (VLDL) contents in blood serum in hyperlipidemia types IIa and IV, respectively, resulted in significant elevation of LPS binding to these fractions . LPS added to the blood serum leads to the dose-dependent decrease in LCAT activity . The revealed phenomena of elevated LPS binding to atherogenic LP fractions in hypercholesterolemia and endotoxin-induced LCAT inhibition suggest the pathogenic role of LPS-LP complexes in atherogenesis.

Indian J Med Res, 2002 Feb, 115, 49 - 54
Nalidixic acid susceptibility test to screen ciprofloxacin resistance in Salmonella typhi; Kapil A et al.; BACKGROUND & OBJECTIVES: Clinical non response to ciprofloxacin therapy in enteric fever is increasingly being encountered in endemic areas possibly due to the increase in the levels of resistance to ciprofloxacin in Salmonella typhi . The antimicrobial susceptibility tests for S . typhi performed by the disc diffusion method using NCCLS breakpoints fail to detect the increasing MIC of ciprofloxacin, leading to the inappropriate treatment of enteric fever with ciprofloxacin . We explored the possibility of testing S . typhi strains for their susceptibility to nalidixic acid by disc diffusion method as a marker for high MIC to ciprofloxacin . METHODS: Isolates (94) of S . typhi were tested for in vitro susceptibility to nalidixic acid (30 micrograms) and ciprofloxacin (5 micrograms) by disc diffusion method using NCCLS guidelines . The MIC of these strains to ciprofloxacin was also determined by E-test . RESULTS: Of the 94 strains tested, 56 were NARST (nalidixic acid resistant S . typhi) and 34 were NASST (nalidixic acid sensitive S . typhi) . MIC of ciprofloxacin in the NASST strains varied from 0.002-0.125 microgram/ml while that for NARST strains varied from 0.023-0.38 microgram/ml, which is about 10-folds higher than that of NASST strains . INTERPRETATION & CONCLUSION: Our study shows that resistance to nalidixic acid is associated with a high MIC to ciprofloxacin in S . typhi . These strains would have been interpreted as ciprofloxacin sensitive by routine antimicrobial susceptibility testing by disc diffusion method . Hence screening of S . typhi isolates by the nalidixic acid susceptibility test may be incorporated in a clinical bacteriology laboratory to alert the treating physicians of the possibility of the failure to ciprofloxacin therapy in patients with enteric fever.

Indian J Med Res, 2002 Feb, 115, 46 - 8
Decreasing trend in the occurrence of Salmonella enterica serotype Typhi amongst hospitalised children in Kolkata, India during 1990-2000; Saha MR et al.; In a prospective hospital based surveillance, 1454 children clinically diagnosed as typhoid fever were enrolled during the period between 1990 to 2000 . Of them 336 (23.1%) children were positive for Salmonella enterica serotype Typhi by blood culture . A declining trend of hospitalization and identification of the pathogen was observed from 1992 to 2000 as compared to 1990-1991 . A declining trend of resistance to the commonly used anti-typhoid drugs was seen in the S . enterica serotype Typhi isolates . Recently in 2000, nine strains were detected as ciprofloxacin resistant . Misuse and overuse of ciprofloxacin for the treatment of typhoid fever influenced the development of ciprofloxacin resistant strains of S . enterica serotype Typhi in and around Kolkata.

Nucleic Acids Res, 2002 Jul 15, 30(14), 3181 - 91
A comparative genomic method for computational identification of prokaryotic translation initiation sites; Walker M et al.; The ever growing number of completely sequenced prokaryotic genomes facilitates cross-species comparisons by genomic annotation algorithms . This paper introduces a new probabilistic framework for comparative genomic analysis and demonstrates its utility in the context of improving the accuracy of prokaryotic gene start site detection . Our frame work employs a product hidden Markov model (PROD-HMM) with state architecture to model the species-specific trinucleotide frequency patterns in sequences immediately upstream and downstream of a translation start site and to detect the contrasting non-synonymous (amino acid changing) and synonymous (silent) substitution rates that differentiate prokaryotic coding from intergenic regions . Depending on the intricacy of the features modeled by the hidden state architecture, intergenic, regulatory, promoter and coding regions can be delimited by this method . The new system is evaluated using a preliminary set of orthologous Pyrococcus gene pairs, for which it demonstrates an improved accuracy of detection . Its robustness is confirmed by analysis with cross-validation of an experimentally verified set of Escherichia coli K-12 and Salmonella thyphimurium LT2 orthologs . The novel architecture has a number of attractive features that distinguish it from previous comparative models such as pair-HMMs.

Biochemistry, 2002 Jul 30, 41(30), 9516 - 24
Interactions among membrane and soluble components of the flagellar export apparatus of Salmonella; Zhu K et al.; Interactions among several components of the flagellar export apparatus of Salmonella were studied using affinity chromatography, affinity blotting, and fluorescence resonance energy transfer (FRET) . The components examined were two integral membrane proteins, FlhA and FlhB, and two soluble components, FliH and the ATPase FliI . Affinity chromatography and affinity blotting demonstrated a heterologous interaction between FlhA and FlhB but not homologous FlhA-FlhA or FlhB-FlhB interactions . Both FlhA and FlhB consist of N-terminal transmembrane domains and C-terminal cytoplasmic domains (FlhA(C) and FlhB(C)) . To study the interactions among the cytoplasmic components (FlhA(C), FlhB(C), FliH, and FliI), FRET measurements were carried out using fluorescein-5-isothiocyanate (FITC) as donor and tetramethylrhodamine-5- (and 6-) isothiocyanate (TRITC) as acceptor . To reveal the nature of the binding interactions, measurements were carried out in physiological buffer, at high salt (0.5 M NaCl) and in 30% 2-propanol . The results indicated that FlhA(C) could bind to FlhB(C) and both FlhA(C) and FlhB(C) could bind to themselves . Both FlhA(C) and FlhB(C) bound to FliH and FliI . Several in-frame deletion mutants of FliH were examined and found to have only minor effects of decreased binding to FlhA(C) and FlhB(C); deletions in the interior of the FliH sequence had a greater effect than those at the N terminus . The FliI mutants examined bound FlhA(C) and FlhB(C) about the same as or slightly more weakly than wild-type FliI . FliH bound more weakly to FliI carrying the N-terminal double mutation R7C/L12P than it did to wild-type FliI, confirming the importance of the N terminus of FliI for its interaction with FliH.

Arch Pharm Res, 2002 Jun, 25(3), 320 - 4
Potent antimutagenic and their anti-lipid peroxidative effect of kaikasaponin III and tectorigenin from the flower of Pueraria thunbergiana; Park KY et al.; The MeOH extract of Pueraria thunbergiana (Leguminosae) flowers and its fractions were subjected to Ames test to test the antimutagenicity . EtOAc fraction (1 mg/plate) decreased the number of revertants of Salmonella typhymurium TA100 by 95% against aflatoxin B, (AFB1) . Phytochemical isolation of the EtOAc fraction afforded four isoflavonoids (tectorigenin, glycitein, tectoridin and glycitin) and one saponin (kaikasaponin III) . Though the three isoflavonoids other than tectoridin showed significant antimutagenicity, the activity of kaikasaponin III was the most potent . Kaikasaponin III (1 mg/plate) decreased the number of revertants of S . typhymurium TA100 by 99% against AFB, but by 75% against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) . Tectorigenin (1 mg/plate) inhibited the AFB1-induced mutagenicity by 90% and MNNG-induced one by 76% . Glycitein and glycitin were less active than tectorigenin and kaikasaponin III . This result suggested that kaikasponin III prevents the metabolic activation of AFB1 and scavenge electrophilic intermediate capable of mutation . The two components with potent activities, tectorigenin and kaikasaonin III, significantly prevented the malondialdehyde formation caused by bromobenzene in the rat.

Front Biosci, 2002 Aug 01, 7, d1857 - 66
Control of gene expression in Gram-positive bacteria: extensions of and departures from enteric paradigms; Zuber P; Our introduction to prokaryotic gene expression has always focused on the operon and regulatory mechanisms that operate within enteric bacteria such as Escherichia coli, Salmonella species, and their phages . While operon organization and many of the components of regulatory networks are conserved in Gram-positive species, there exists unique features that set these organisms apart from the enterics . Two examples are presented herein: carbon catabolite control and regulation of RNA polymerase sigma subunit activity, are presented . The accompanying reviews highlight the diversity and novel aspects of genetic control in Gram-positive bacteria, with descriptions of quorum-sensing systems, transcriptional control, and RNA processing mechanisms.

J South Orthop Assoc, 2001 Spring, 10(1), 57 - 60
Septic sacroiliitis: the overlooked diagnosis; Attarian DE; Infection of the sacroiliac joint is extraordinarily rare . However, the initial symptoms and signs associated with this condition are mundane, thus leading to delay in diagnosis, or even misdiagnosis . I report an extremely unusual pyogenic sacroiliitis caused by Salmonella and discuss key clinical components and protocol for the successful evaluation, diagnosis, and treatment of this uncommon illness.

Mol Phylogenet Evol, 2002 Jul, 24(1), 102 - 20
Detection of recombination among Salmonella enterica strains using the incongruence length difference test; Brown EW et al.; Particular serovars of Salmonella enterica have emerged as significant foodborne pathogens in humans . At the chromosomal level, discrete regions in the Salmonella genome have been identified that are known to play important roles in the maintenance, survival, and virulence of S . enterica within the host . Interestingly, several of these loci appear to have been acquired by horizontal transfer of DNA among and between bacterial species . The profound importance of recombination in pathogen emergence is just now being realized, perhaps explaining the sudden interest in developing novel and facile ways for detecting putative horizontal transfer events in bacteria . The incongruence length difference (ILD) test offers one such means . ILD uses phylogeny to trace sequences that may have been acquired promiscuously by exchange of DNA during chromosome evolution . We show here that the ILD test readily detects recombinations that have taken place in several housekeeping genes in Salmonella as well as genes composing the type 1 pilin complex (14 min) and the inv-spa invasion gene complex (63 min) . Moreover, the ILD test indicated that the mutS gene (64 min), whose product helps protect the bacterial genome from invasion by foreign DNA, appears to have undergone intragenic recombination within S . enterica subspecies I . ILD findings were supported using additional tests known to be independent of the ILD approach (e.g., split decomposition analysis and compatibility of sites) . Taken together, these data affirm the application of the ILD test as one approach for identifying recombined sequences in the Salmonella chromosome . Furthermore, horizontally acquired sequences within mutS support a model whereby evolutionarily important recombinants of S . enterica are rescued from strains carrying defective mutS alleles via horizontal transfer.

Vet Immunol Immunopathol, 2002 Sep 25, 88(3-4), 183 - 96
Characterisation of a resource population of pigs screened for resistance to salmonellosis; van Diemen PM et al.; The degree of resistance to Salmonella choleraesuis infection in a reference family purposely bred to map resistance genes was assessed . Aspects of the innate and specific immune system were studied to find a parameter that might predict the resistance of pigs to salmonellosis . The family was bred from commercial full-sister pairs of F1-gilts and four boars . One boar (G398) was identified as breeding susceptible offspring, and one boar (G402) as breeding resistant offspring on the basis of pyrexial responses and numbers of Salmonella in liver and spleen post mortem . The other two boars were classified as 'possible resistant' (Y2008) and 'unknown' (Y6101) respectively . Functional differences in immune cells (neutrophils and lymphocytes) between the offspring of G398 and G402 were detected . The most resistant piglets had a higher number of circulating neutrophils and better polymorphonuclear neutrophils (PMNs) function, but a lower mitogenic response of lymphocytes both pre- and post-infection and a lower antibody response . Between the offspring groups of Y2008 and Y6101 no differences were found in the number of viable Salmonella in liver and spleen at post mortem or in immune cell function, however, the survival rate of these offspring groups was clearly different . Twenty three percent of the Y2008-offspring and 33% of the Y6101-offspring reached the predetermined humane clinical endpoint before the end of the experiment . Our findings suggest a role for several inherited immunological traits, including PMN function and lecithin-induced mitogenic proliferation, which appear to influence resistance to salmonellosis.

Vaccine, 2002 Jul 26, 20(23-24), 3034 - 41
The effect of vaccination with a Salmonella enteritidis aroA mutant on early cellular responses in caecal lamina propria of newly-hatched chickens; Van Immerseel F et al.; When newly hatched chicks are inoculated with a Salmonella strain, they induce a rapid onset of resistance to intestinal colonization by other Salmonella strains . The exact mechanism of this early colonization-inhibition is not known . To study host-related contributions to this phenomenon, the kinetics of immune cell infiltration in the caecal wall was analyzed during the first 10 days after vaccination of newly hatched chickens with a Salmonella enterica serovar Enteritidis aroA mutant, and infection 1 day later with a virulent S . enterica serovar Enteritidis strain . These data were correlated with bacterial colonization and clearance of the Salmonella Enteritidis challenge strain . Bacteriological data showed that vaccinated animals had a much lower number of challenge bacteria in their organs and caecal contents the first days post-challenge, relative to unvaccinated animals . Immunohistochemical analysis of the caecal lamina propria revealed that heterophils started infiltrating the caecal lamina propria from 12 h post-vaccination . Macrophages and T-lymphocytes started infiltrating from 20 h and B-lymphocytes from 24 h post-vaccination . These data imply that immune cells already colonized the caecal wall at the time of challenge in vaccinated animals . The presence and activity of these cells in the caecal wall shortly after administration of a Salmonella Enteritidis aroA mutant might contribute to the inhibition of colonization of a virulent Salmonella strain, subsequently administered.

J Vector Ecol, 2002 Jun, 27(1), 82 - 5
Isolation of Salmonella from muscoid flies at commercial animal establishments in San Bernardino County, California; Mian LS et al.; Adult muscoid flies collected from three dairies and eight commercial poultry ranches in San Bernardino County were tested for Salmonella enteritidis . Of the total 2,686 flies tested, 92.3% were Musca domestica, 5.5% Fannia canicularis, 1.9% Ophyra leucostoma, 0.2% Phaenicia sericata, and <0.1% Muscina stabulans . Whereas flies at the dairies belonged exclusively to M . domestica, faunal composition at the poultry ranches was more diverse, including all five species . Among the five fly species, only M . domestica tested positive for serotypes of S . enteritidis . The six isolates from fly pools (25-50 flies per pool) collected from dairies included five S . enteritidis serotype Kentucky and one S . enteritidis ser . Muenster . Isolates from flies collected at poultry ranches were three S . enteritidis ser . Braenderup, S . enteritidis ser . Kottbus, and S . enteritidis ser . Montevideo . The male to female ratio in M . domestica testing positive for S . enteritidis serotypes, was 3 to 8 pools, showing more female than male flies carrying the organism.

J Mol Microbiol Biotechnol, 2002 Jul, 4(4), 367 - 74
Enhancer-dependent transcription in Salmonella enterica Typhimurium: new members of the sigmaN regulon inferred from protein sequence homology and predicted promoter sites; Studholme DJ; DNA-looping mediated by regulatory proteins is a ubiquitous mode of transcriptional control that allows interactions between genetic elements separated over long distances in DNA . In prokaryotes, one of the best-studied examples of regulatory proteins that use DNA-looping is the NtrC family of enhancer-binding proteins (EBPs), which activate transcription from sigmaN (sigma-N, sigma-54) dependent promoters . The completely sequenced genome of food-borne pathogen Salmonella enterica serovar Typhimurium LT2 contains seven novel EBPs of unknown function . Four of these EBPs have a similar domain organisation to NtrC whilst surprisingly the remaining three resemble LevR in Bacillus subtilis . Probable transcriptional targets are identified for each of the EBPs, including novel homologues of phosphotransferase system Enzyme II (EII) and several virulence-associated functions . Comparisons are made with the related enteric bacteria Salmonella Typhi, Escherichia coli and Yersinia pestis.

Acta Chir Orthop Traumatol Cech, 2002, 69(3), 187 - 90
{Purulent Salmonella arthritis of the ankle joint}; Zan J et al.; In the case study the authors focus on Salmonella enteritidis which caused purulent osteoarthritis of the ankle and sepsis . Salmonella osteoarthritis is one of the nidal forms of the salmonella infection . The authors briefly present etiology, pathogenesis, diagnosis and principles of the treatment of infectious osteoarthritis . They analyze a case of a 56 years old immunocompromised patient who was treated at the authors' department for a late diagnosis with an already developed septicemia . They describe the course of the disease, complications and the result of the treatment and discuss the pitfalls of the diagnosis and treatment . Only a timely diagnosis followed by a sufficiently vigorous surgical intervention with drainage of the joint and combined with a timely, targeted and long-term antibiotic therapy leads to the management of this severe nosologic unit.

Int J Infect Dis, 2002 Jun, 6(2), 98 - 102
Foodborne disease in our global village: a multinational investigation of an outbreak of Salmonella serotype Enteritidis phage type 4 infection in Puerto Vallarta, Mexico; Shane AL et al.; OBJECTIVES: In late 1996, a multinational investigation was launched following an outbreak of diarrheal illness that caused the disruption of an international scientific conference at a first-class hotel in Puerto Vallarta, Mexico . METHODS: A questionnaire was mailed to all American and to selected international attendees . Additional copies of the questionnaire were provided for any family members who may have attended the conference . A case was defined as an illness with three or more loose stools during a 24-h period in a conference attendee or accompanying family member, with illness lasting 2 or more days and onset between 6 and 9 November 1996 . RESULTS: Questionnaires were returned by 81% (232/288) of American attendees, 47% (18/38) of selected international attendees, and 25 family members; 30% (83/275) of respondents met the case definition . Ill persons resided in at least seven countries . Salmonella serotype Enteritidis phage type 4 was isolated from stool specimens from patients residing in Canada, the UK, and the USA . Attending a hotel banquet on 6 November was associated with illness; 42% (82/194) of banquet attendees became ill versus 3% (1/37) of non-attendees (relative risk (RR)515.6, 95% confidence interval (CI)52.3-108.9) . The only banquet food item associated with illness was chili rellenos; 53% (58/109) of persons who ate chili rellenos were ill versus 22% (12/55) of those who did not (RR52.4, 95% CI51.4-4.1) . Chili rellenos ingredients included shelled eggs and cheese; Salmonella was isolated from the leftover cheese but the isolate was not serotyped . CONCLUSIONS: Salmonella may be a cause of traveler's diarrhea and can result in outbreaks even among travelers who follow routine precautions (i.e . staying in a first-class hotel and eating hot foods) . International collaboration in investigating similar outbreaks, including sharing subtyping results, will be necessary for long-term prevention . Global Salm-Surv, an international network of Salmonella reference laboratories coordinated by the World Health Organization, may facilitate such collaboration.

Int J Infect Dis, 2002 Jun, 6(2), 94 - 7
Increasing incidence of nontyphi Salmonella bacteremia among children living in southern Israel; Yagupsky P et al.; OBJECTIVES: To determine if the epidemiology of Salmonella gastroenteritis and childhood bacteremia among the two ethnic populations (Jews and Bedouins) living in southern Israel has changed in recent years . METHODS: Retrospective review of laboratory records and medical charts of patients from whom non-typhi salmonellae were isolated from stool and blood cultures in the 1990-1995 period . RESULTS: The overall incidence of enteric Salmonella infections was 123.5 per 100 000 inhabitants and remained stable during the study period . The incidence of bacteremia among children younger than 4 years increased from 9.3 per 100 000 in the 1990-1992 period to 26.8 per 100 000 in the 1993-1995 period (P 0.01) . This increment was especially caused by Salmonella virchow and S . enteritidis, which were also isolated with increasing frequency from stool cultures . The Bedouin population was underrepresented among stool isolates, whereas its representation among blood isolates closely resembled the fraction of this ethnic group in the overall population of the area . CONCLUSIONS: The incidence of enteric salmonellosis has remained stable at a high endemic level in recent years in southern Israel . The incidence of children's bacteremia has experienced a significant increase, associated with S . virchow and S . enteritidis . Differences in the utilization of medical services may explain differences in the epidemiology of Salmonella infections found in the two resident ethnic groups.

Rev Gastroenterol Disord, 2001, 1(4), 177 - 86
Emerging foodborne pathogens: keeping your patients and your families safe; Oldfield EC 3rd; Changes in food production and societal pressures have led to a continuing increase in the incidence of foodborne illness . Many pathogens are associated with specific foods, e.g., E . coli O157:H7 with hamburgers or Salmonella with eggs . The U.S . Food and Drug Administration has recently approved irradiation for sterilization of meat, but public acceptance of irradiated food is low . Because contaminated foods are seldom detected before they reach store shelves, care in food preparation by professional and home cooks is crucial.

J Biol Chem, 2002 Sep 27, 277(39), 36755 - 9 Epub 2002 Jul 15.
Subunit organization in a soluble complex of tar, CheW, and CheA by electron microscopy; Francis NR et al.; The Salmonella and Escherichia coli aspartate receptor, Tar, is representative of a large class of membrane receptors that generate chemotaxis responses by regulating the activity of an associated histidine protein kinase, CheA . Tar is composed of an NH(2)-terminal periplasmic ligand-binding domain linked through a transmembrane sequence to a COOH-terminal coiled-coil signaling domain in the cytoplasm . The isolated cytoplasmic domain of Tar fused to a leucine zipper sequence forms a soluble complex with CheA and the Src homology 3-like kinase activator, CheW . Activity of the CheA kinase in the soluble complex is essentially the same as in fully active complexes with the intact receptor in the membrane . The soluble complex is composed of approximately 28 receptor cytoplasmic domain chains, 6 CheW chains, and 4 CheA chains . It has a molecular weight of 1,400,000 (Liu, I., Levit, M., Lurz, R., Surette, M.G., and Stock, J.B . (1997) EMBO J . 16, 7231-7240) . Electron microscopy reveals an elongated barrel-like structure with a largely hollow center . Immunoelectron microscopy has provided a general picture of the subunit and domain organization of the complex . CheA and CheW appear to be in the middle of the complex with the leucine zippers of the receptor construct at the ends . These findings show that the receptor signaling complex forms higher ordered structures with defined geometric architectures . Coupled with atomic models of the subunits, our results provide insights into the functional architecture by which the receptor regulates CheA kinase activity during bacterial chemotaxis.

Biochemistry, 2002 Jul 23, 41(29), 9079 - 89
Structural studies of the L-threonine-O-3-phosphate decarboxylase (CobD) enzyme from Salmonella enterica: the apo, substrate, and product-aldimine complexes; Cheong CG et al.; The evolution of biosynthetic pathways is difficult to reconstruct in hindsight; however, the structures of the enzymes that are involved may provide insight into their development . One enzyme in the cobalamin biosynthetic pathway that appears to have evolved from a protein with different function is L-threonine-O-3-phosphate decarboxylase (CobD) from Salmonella enterica, which is structurally similar to histidinol phosphate aminotransferase {Cheong, C . G., Bauer, C . B., Brushaber, K . R., Escalante-Semerena, J . C., and Rayment, I . (2002) Biochemistry 41, 4798-4808} . This enzyme is responsible for synthesizing (R)-1-amino-2-propanol phosphate which is the precursor for the linkage between the nucleotide loop and the corrin ring in cobalamin . To understand the relationship between this decarboxylase and the aspartate aminotransferase family to which it belongs, the structures of CobD in its apo state, the apo state complexed with the substrate, and its product external aldimine complex have been determined at 1.46, 1.8, and 1.8 A resolution, respectively . These structures show that the enzyme steers the breakdown of the external aldimine toward decarboxylation instead of amino transfer by positioning the carboxylate moiety of the substrate out of the plane of the pyridoxal ring and by placing the alpha-hydrogen out of reach of the catalytic base provided by the lysine that forms the internal aldimine . It would appear that CobD evolved from a primordial PLP-dependent aminotransferase, where the selection was based on similarities between the stereochemical properties of the substrates rather than preservation of the fate of the external aldimine . These structures provide a sequence signature for distinguishing between L-threonine-O-3-phosphate decarboxylase and histidinol phosphate aminotransferases, many of which appear to have been misannotated.

MMWR Morb Mortal Wkly Rep, 2002 Jun 28, 51(25), 545 - 8
Outbreak of multidrug-resistant Salmonella newport--United States, January-April 2002; Endocarditis and pericarditis caused by Salmonella paratyphi A: two case reports and review of the literature; Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand . chitsanu.p@chula.ac.th

We report on two children with paratyphoid fever and rare cardiac complications (endocarditis and pericarditis) during an outbreak of Salmonella paratyphi A infection in Bangkok, Thailand, in 1996 . Both of the patients had underlying congenital heart disease . Two cases in the literatures of endocarditis and five cases of pericarditis caused by Salmonella paratyphi were reviewed . These rare cardiac complications should be considered among persons who reside in an endemic area of enteric fever or during disease outbreaks, especially in children with underlying heart diseases.

Infect Immun, 2002 Aug, 70(8), 4721 - 5
Role of the high-affinity zinc uptake znuABC system in Salmonella enterica serovar typhimurium virulence; Campoy S et al.; The Salmonella enterica serovar Typhimurium znuABC genes encoding a high-affinity zinc uptake system and its regulatory zur gene have been cloned . Salmonella serovar Typhimurium zur and znuC knockout mutants have been constructed by marker exchange . The 50% lethal dose of the znuC mutant increased when either orally or intraperitoneally inoculated in BALB/c mice, while virulence of the zur mutant decreased only when mice were intraperitoneally challenged.

Infect Immun, 2002 Aug, 70(8), 4414 - 23
Molecular cloning and characterization of genes for Shigella sonnei form I O polysaccharide: proposed biosynthetic pathway and stable expression in a live salmonella vaccine vector; Xu DQ et al.; The gene region for biosynthesis of Shigella sonnei form I O polysaccharide (O-Ps) and flanking sequences, totaling >18 kb, was characterized by deletion analysis to define a minimal construct for development of Salmonella-based live vaccine vector strains . Lipopolysaccharide (LPS) expression and DNA sequence studies of plasmid deletion derivatives indicated form I O-Ps expression from a 12.3-kb region containing a putative promoter and 10 contiguous open reading frames (ORFs), one of which is the transposase of IS630 . A detailed biosynthetic pathway, consistent with the predicted functions of eight of the nine essential ORFs and the form I O-Ps structure, is proposed . Further sequencing identified partial IS elements (i.e., IS91 and IS630) and wzz upstream of the form I coding region and a fragment of aqpZ and additional full or partial IS elements (i.e., IS629, IS91, and IS911) downstream of this region . The stability of plasmid-based form I O-Ps expression was greater from low-copy vectors than from high-copy vectors and was enhanced by deletion of the downstream IS91 from plasmid inserts . Both core-linked (i.e., LPS) and non-core-linked (i.e., capsule-like) surface expression of form I O-Ps were detected by Western blotting and silver staining of polyacrylamide gel electrophoresis-separated Shigella and Escherichia coli extracts . However, salmonellae, which have a core that is chemically dissimilar to that of shigellae, expressed only non-core-linked surface-associated form I O-Ps . Finally, attenuated Salmonella enterica serovar Typhi live vaccine vector candidates, containing minimal-sized form I operon constructs, elicited immune protection in mice against virulent S . sonnei challenge, thereby supporting the promise of live, oral vaccines for the prevention of shigellosis.

Infect Immun, 2002 Aug, 70(8), 4399 - 405
Flavohemoglobin Hmp protects Salmonella enterica serovar typhimurium from nitric oxide-related killing by human macrophages; Stevanin TM et al.; Survival of macrophage microbicidal activity is a prerequisite for invasive disease caused by the enteric pathogen Salmonella enterica serovar Typhimurium . Flavohemoglobins, such as those of Escherichia coli, Salmonella, and yeast, play vital roles in protection of these microorganisms in vitro from nitric oxide (NO) and nitrosative stress . A Salmonella hmp mutant defective in flavohemoglobin (Hmp) synthesis exhibits growth that is hypersensitive to nitrosating agents . We found that respiration of this mutant exhibited increased inhibition by NO, whereas wild-type cells pregrown with sodium nitroprusside or S-nitrosoglutathione showed enhanced tolerance of NO . Most significantly, hmp mutants internalized by primary human peripheral monocyte-derived macrophages survived phagocytosis relatively poorly compared with similarly bound and internalized wild-type cells . That the enhanced sensitivity to macrophage microbicidal activity is due primarily to the failure of Salmonella to detoxify NO was suggested by the ability of L-N(G)-monomethyl arginine-an inhibitor of NO synthase-to eliminate the difference in killing between wild-type and hmp mutant Salmonella cells . These observations suggest that Salmonella Hmp contributes to protection from NO-mediated inhibition by human macrophages.

Infect Immun, 2002 Aug, 70(8), 4273 - 81
Fimbriated Salmonella enterica serovar typhimurium abates initial inflammatory responses by macrophages; Pascual DW et al.; Oral immunization of mice with a Salmonella vaccine expressing colonization factor antigen I (CFA/I) from enterotoxigenic Escherichia coli results in the rapid onset of interleukin-4 (IL-4) and IL-5 production, which explains the observed elevations in mucosal immunoglobulin A (IgA) and serum IgG1 antibodies . In contrast, oral immunization with the Salmonella vector does not result in the production of Th2-type cytokines . To begin to assess why such differences exist between the two strains, it should be noted that in vitro infection of RAW 264.7 macrophages resulted in the absence of nitric oxide (NO) production in cells infected with the Salmonella-CFA/I vaccine . This observation suggests differential proinflammatory cytokine production by these isogenic Salmonella strains . Upon measurement of proinflammatory cytokines, minimal to no tumor necrosis factor alpha (TNF-alpha), IL-1alpha, IL-1beta, or IL-6 was produced by Salmonella-CFA/I-infected RAW 264.7 or peritoneal macrophages, but production was greatly induced in Salmonella vector-infected macrophages . Only minute levels of IL-12 p70 were induced by Salmonella vector-infected macrophages, and none was induced by Salmonella-CFA/I-infected macrophages . The absence of IL-12 was not due to overt increases in production of either IL-12 p40 or IL-10 . CFU measurements taken at 8 h postinfection showed no differences in colonization in RAW 264.7 cells infected with either Salmonella construct, but there were differences in peritoneal macrophages . However, after 24 h, the Salmonella vector strain colonized to a greater extent in RAW 264.7 cells than in peritoneal macrophages . Infection of RAW 264.7 cells or peritoneal macrophages with either Salmonella construct showed no difference in macrophage viabilities . This evidence shows that the expression of CFA/I fimbriae alters how macrophages recognize or process salmonellae and prevents the rapid onset of proinflammatory cytokines which is typical during Salmonella infections.

Infect Immun, 2002 Aug, 70(8), 4075 - 82
Bacterium-induced CXCL10 secretion by osteoblasts can be mediated in part through toll-like receptor 4; Gasper NA et al.; Two common pathogens known to cause bone infection, Salmonella and Staphylococcus aureus, were investigated to determine their abilities to induce chemokine expression in cultured mouse and human osteoblasts . While these cells are responsible for bone formation, we were surprised to find that they could respond to bacterial infection by upregulating expression of the chemokine CXCL10 (IP-10) . However, there were significant differences in the abilities of the gram-negative bacterium Salmonella and the gram-positive bacterium S . aureus to induce expression of CXCL10 . Reverse transcription-PCR and enzyme-linked immunosorbent assay analyses showed high levels of Salmonella-induced CXCL10 mRNA and protein expression, respectively, whereas the osteoblast response to S . aureus was significantly less . Consistent with these findings, Salmonella-derived lipopolysaccharide (LPS), but not S . aureus-derived peptidoglycan, could induce expression of CXCL10 . An antibody against toll-like receptor 4 (TLR4) could block the LPS-induced CXCL10 production, demonstrating the functional expression of TLR4 by osteoblasts . Despite the inducible nature of TLR2 mRNA expression by bacterium-infected osteoblasts, peptidoglycan failed to stimulate CXCL10 secretion . Immunofluorescent staining of bacterium-infected calvaria (i.e., skull bone) demonstrated the presence of CXCL10 in osteoblasts . The fact that osteoblasts did not express CXCR3 mRNA, whereas T lymphocytes can express high levels of this receptor, suggests that osteoblast-derived CXCL10 may recruit T lymphocytes to the sites of bone infections.

Infect Immun, 2002 Aug, 70(8), 4009 - 18
Salmonella enterica serovar Typhi live vector vaccines delivered intranasally elicit regional and systemic specific CD8+ major histocompatibility class I-restricted cytotoxic T lymphocytes; Pasetti MF et al.; We investigated the ability of live attenuated Salmonella enterica serovar Typhi strains delivered to mice intranasally to induce specific cytotoxic T-lymphocyte (CTL) responses at regional and systemic levels . Mice immunized with two doses (28 days apart) of Salmonella serovar Typhi strain Ty21a, the licensed oral typhoid vaccine, and genetically attenuated mutants CVD 908 (DeltaaroC DeltaaroD), CVD 915 (DeltaguaBA), and CVD 908-htrA (DeltaaroC DeltaaroD DeltahtrA) induced CTL specific for Salmonella serovar Typhi-infected cells in spleens and cervical lymph nodes . CTL were detected in effector T cells that had been expanded in vitro for 7 days in the presence of Salmonella-infected syngeneic splenocytes . A second round of stimulation further enhanced the levels of specific cytotoxicity . CTL activity was observed in sorted alphabeta+ CD8+ T cells, which were remarkably increased after expansion, but not in CD4+ T cells . CTL from both cervical lymph nodes and spleens failed to recognize Salmonella-infected major histocompatibility complex (MHC)-mismatched cells, indicating that the responses were MHC restricted . Studies in which MHC blocking antibodies were used showed that H-2L(d) was the restriction element . This is the first demonstration that Salmonella serovar Typhi vaccines delivered intranasally elicit CD8+ MHC class I-restricted CTL . The results further support the usefulness of the murine intranasal model for evaluating the immunogenicity of typhoid vaccine candidates at the preclinical level.

J Food Prot, 2002 Jul, 65(7), 1177 - 8
A nucleic acid sequence-based amplification method to detect Salmonella enterica serotype enteritidis strain PT4 in liquid whole egg; Cook N et al.; Nucleic acid sequence-based amplification (NASBA) was applied to the detection of Salmonella enterica cells in liquid whole egg . Samples (25 g) of liquid whole egg inoculated with Salmonella cells were enriched for 16 h in buffered peptone water, and the NASBA procedure was effective in detecting the presence of Salmonella in samples inoculated with 10 to 100 CFU prior to enrichment.

J Food Prot, 2002 Jul, 65(7), 1093 - 9
Relationship of cell surface charge and hydrophobicity to strength of attachment of bacteria to cantaloupe rind; Ukuku DO et al.; The cantaloupe melon has been associated with outbreaks of Salmonella infections . It is suspected that bacterial surface charge and hydrophobicity may affect bacterial attachment and complicate bacterial detachment from cantaloupe surfaces . The surface charge and hydrophobicity of strains of Salmonella, Escherichia coli (O157:H7 and non-O157:H7), and Listeria monocytogenes were determined by electrostatic and hydrophobic interaction chromatography, respectively . Initial bacterial attachment to cantaloupe surfaces and the ability of bacteria to resist removal by washing with water were compared with surface charge and hydrophobicity . Whole cantaloupes were submerged in inocula containing individual strains or in cocktails containing Salmonella, E . coli, and L . monocytogenes, either as a mixture of strains containing all three genera or as a mixture of strains belonging to a single genus, for 10 min . Inoculated cantaloupes were dried for 1 h in a biosafety cabinet and then stored for up to 7 days at 4 degrees C . Inoculated melons were washed with water, and bacteria still attached to the melon surface, as well as those in the wash water, were enumerated . Initial bacterial attachment was highest for individual strains of E . coli and lowest for L . monocytogenes, but Salmonella exhibited the strongest attachment on days 0, 3, and 7 . When mixed-genus cocktails were used, the relative degrees of attachment of the three genera ware altered . The attachment of Salmonella strains was the strongest . but the attachment of E . coli was more extensive than that of L . monocytogenes on days 0, 3, and 7 . There was a linear correlation between bacterial cell surface hydrophobicity (r2 = 0.767), negative charge (r2 = 0.738), and positive charge (r2 = 0.724) and the strength of bacterial attachment to cantaloupe surfaces.

J Med Assoc Thai, 2002 Mar, 85(3), 388 - 91
Salmonella neck abscess; Cutchavaree A; Salmonella neck abscesses have rarely been reported in the world literature . Two patients with underlying diabetes mellitus developed deep neck abscesses which did not respond to empirical antimicrobials . Diagnosis of salmonella infection was made by culture of the discharge . Successful treatment was obtained by prescribing appropriate antibiotics and proper drainage.

Cell Microbiol, 2002 Jun, 4(6), 357 - 65
Involvement of SipA in modulating actin dynamics during Salmonella invasion into cultured epithelial cells; Higashide W et al.; Salmonella entry into epithelial host cells results from the host actin cytoskeleton reorganization that is induced by a group of bacterial proteins delivered to the host cells by the Salmonella type III secretion system . SopE, SopE2 and SopB activate CDC42 and Rac1 to intercept the signal transduction pathways involved in actin cytoskeleton rearrangements . SipA and SipC directly bind actin to modulate the actin dynamics facilitating bacterial entry . Biochemical studies have indicated that SipA decreases the critical concentration for actin polymerization and may be involved in promoting the initial actin polymerization in Salmonella-induced actin reorganization . In this report, we conducted experiments to analyze the in vivo function(s) of SipA during Salmonella invasion . SipA was found to be preferentially associated with peripheral cortical actin filaments but not stress fibres using permeabilized epithelial cells . When polarized Caco-2 cells were infected with Salmonella, actin cytoskeleton rearrangements induced by the wild-type strain had many filopodia structures that were intimately associated with the bacteria . In contrast, ruffles induced by the sipA null mutant were smoother and distant from the bacteria . We also found that the F-actin content in cells infected with the sipA mutant decreased nearly 80% as compared to uninfected cells or those infected with the wild-type Salmonella strain . Furthermore, expression of either the full-length or the SipA(459-684) actin-binding fragment induced prominent punctuate actin assembly in the cortical region of COS-1 cells . These results indicate that SipA is involved in modulating actin dynamics in cultured epithelial cells during Salmonella invasion.

Arch Microbiol, 2002 Aug, 178(2), 94 - 101 Epub 2002 May 15.
Role of SdiA in Salmonella enterica serovar Typhimurium physiology and virulence; Volf J et al.; sdiAin Salmonella enterica serovar Typhimurium encodes a protein belonging to the LuxR family of transcriptional regulators . Initial computer analysis revealed the presence of a fur box 19 bp upstream of the start codon of the sdiA gene and a helix-turn-helix motif in the carboxy-terminal part of the SdiA protein typical for transcriptional regulators . Deletion of the furbox resulted in twofold increase of sdiA transcription . Furthermore, addition of dipyridyl, an iron chelator, to culture media increased sdiA transcription to the level observed in the fur box mutant, confirming that sdiA is suppressed in the presence of iron . When S . entericasv . Typhimurium was grown in conditioned medium, sdiA transcription was repressed to 30% of that in cells grown in fresh LB broth; this repression was independent of the fur box . Oral infection of mice with the strain lacking the helix-turn-helix domain of SdiA indicated increased virulence of this S . entericasv . Typhimurium mutant . sdiA, dually controlled by iron concentration and culture-density-derived signals, may therefore play an important role in S . entericasv . Typhimurium virulence regulation.

Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai), 1999, 31(4), 367 - 372
Simultneous Expression of CS3 Colonization Factor Antigen and Cholera Toxin B Subunit in Salmonella typhi; Han ZZ et al.; A host-plasmid balancing system was established based on asd gene in an avirulent strain of Salmonella typhi to express enterotoxigenic E.coli surface antigen CS3 and V.cholerae toxin subunit B(CTB) . The plasmid can be stably maintained in the host and can express CS3 and CTB in the host cell without any antibiotic selection, although expression level and growth characteristics of the recombinant strain expressing either CS3 or CTB are superior to that of the recombinant strain which expresses both of the antigens . Antibo-dies against CS3 and CTB can be detected in sera of mice immunized with recombinant bacteria either orally or subcutaneously, and mice immunized subcutaneously can be protected from challenging with virulent strain of Salmonella typhi . This work may be helpful in constructing multivalent recombinant vaccines for prevention of bacterial diarrhea.

Prev Vet Med, 2002 Jul 25, 54(3), 279 - 89
Probability of and risk factors for introduction of infectious diseases into Dutch SPF dairy farms: a cohort study; van Schaik G et al.; A 2-year cohort study was conducted to investigate the probability of disease introduction into Dutch dairy farms . The farms were tested regularly for diseases and were visited biannually to collect management data . Ninety-five specific pathogen-free (SPF) dairy farms were selected from a database of bovine herpesvirus type 1 (BHV1)-free farms to study the probability of, and risk factors for, introduction of BHV1, bovine viral diarrhoea virus (BVDV), Salmonella enterica subsp . enterica serotype Dublin (S . dublin), and Leptospira interrogans serovar hardjo (L . hardjo).Although most of the 95 SPF farms had a low risk on introduction of infectious diseases, one disease was introduced into 12 farms and two diseases were introduced into one farm . Three farms experienced an outbreak of BHV1, one farm an outbreak of L . hardjo, two farms BVDV, six farms S . dublin, and one farm both BHV1 and S . dublin . The total incidence rate was 0.09 (0.06-0.12) per herd-year at risk . The results suggest that the "non-outbreak" farms were significantly more closed than the "outbreak" farms . Direct animal contacts with other cattle should be avoided and professional visitors should be instructed to wear protective clothing before handling cattle.

FEMS Microbiol Lett, 2002 Jul 2, 212(2), 221 - 8
Identification of a type III secretion system in uropathogenic Escherichia coli; Miyazaki J et al.; To determine virulence-related genes in uropathogenic Escherichia coli (UPEC) showing invasiveness to T-24 bladder cancer cells, genomic subtractive hybridization was performed between a highly invasive and a less invasive strain . Forty-nine DNA fragments were isolated from the invasive strain . One of them showed homology with Salmonella invA gene . By chromosomal walking of the strain, a type III secretion system that has been described in E . coli O157:H7 was identified on the genome of the invasive strains . Three strains out of 100 UPEC isolates had a type III secretion system inserted at 64 min of the chromosome, corresponding to E . coli K-12 MG1655 . This finding suggested that the type III secretion system could play a part in uropathogenicity of UPEC.

Acta Vet Hung, 2002, 50(2), 161 - 6
Polymerase chain reaction amplification of 16S-23S spacer region for rapid identification of Salmonella serovars; Bakshi CS et al.; Polymerase chain reaction (PCR) was used to amplify the spacer regions between the 16S and 23S genes of rRNA genetic loci of Salmonella serovars for their rapid identification . These genetic loci revealed a significant level of polymorphism in length across the species/serovar lines . When the 16S-23S spacer region amplification products were subjected to agarose electrophoresis, the patterns observed could be used to distinguish all the serovars of Salmonella tested . Unique elements obtained in amplification products were mostly clustered at serovar level, although certain genus-specific patterns were also observed . On the basis of the results obtained, the amplification of 16S-23S ribosomal spacer region could suitably be used in a PCR-based identification method for Salmonella serovars.

Proteomics, 2002 Jun, 2(6), 792 - 9
Proteomic approaches to Salmonella Pathogenicity Island 2 encoded proteins and the SsrAB regulon; Deiwick J et al.; Type III protein secretion is a common virulence determinant in Gram-negative bacteria and the genetic information is often clustered in pathogenicity islands or on virulence plasmids . We have analyzed the type III secretion system encoded by Salmonella Pathogenicity Island 2 (SPI2) that is indispensable for systemic disease of Salmonella enterica serotype Typhimurium (S . Typhimurium) in mice . Since the low abundance of this secretion system restricted direct analysis by proteomic approaches, several putative proteins were expressed as recombinant products and analyzed by two-dimensional electrophoresis . The map obtained for SPI2 encoded proteins was correlated to the expression pattern of S . Typhimurium . The latter was compared to the proteins induced by SsrAB, the two-component system regulating SPI2 gene expression . Our results exemplify that recombinant expression is a complementary tool for analysis of low abundant proteins or membrane proteins . This approach contributes to the characterization of these proteins by subcellular fractionation . Furthermore, we show that pulse labeling was necessary to analyze growth phase regulated SPI2 proteins that might not be otherwise detectable.

J Infect Chemother, 2002 Jun, 8(2), 185 - 6
A rare case of Salmonella soft-tissue abscess; Minohara Y et al.; A healthy 6-year-old boy had complained of fever and chest pain for 3 days . On admission, he had a mass on the sternum, 3.7 x 2.5 cm in size . Abnormal laboratory findings included a white blood cell count of 12,900/microl, erythrocyte sedimentation rate (ESR), 74 mm/h, and C-reactive protein (CRP), 9.7 mg/dl . Ultrasound examination of the chest revealed a hypoechoic lesion on the sternum that was 30 x 15 mm in size . Chest computed tomography (CT) scan showed no bone fracture or bone erosion . The patient received cefpirome, given intravenously at 60 mg/kg per day for 10 days . Incision and drainage was performed on the seventh day in the hospital, and we collected 0.5 ml of pus . Salmonella enteritidis was detected from the drainage . However, the patient had no gastrointestinal symptoms . He was discharged on the fourteenth hospital day, as he was asymptomatic . Results of all physical and laboratory examinations including blood and stool cultures and ultrasound examinations, were within the normal limits upon discharge.

FEMS Immunol Med Microbiol, 2002 Jul 12, 33(3), 165 - 71
Lack of clonal relationship between non-typhi Salmonella strain types from humans and those isolated from animals living in close contact; Kariuki S et al.; Antibiogram patterns and chromosomal DNA typing were used to compare 151 non-typhoidal Salmonella spp . (NTS) isolated from patients and 78 from animals, environmental or food specimens obtained within or near the homes of patients with invasive salmonellosis . The majority of NTS from humans (137; 90.7%) were Salmonella enterica serotype Typhimurium (S . Typhimurium) and S . Enteritidis . Chicken specimens and feeds produced (24; 52.2%) S . Enteritidis, while S . Agona was the predominant (20; 77%) serovar among pigs and dairy cows . The majority (97; 64.2%) of NTS from humans were multidrug resistant, while NTS from cows, pigs, beef carcass swabs and sewers were fully susceptible to all antibiotics tested . Pulsed-field gel electrophoresis patterns of XbaI-digested genomic DNA of NTS from the humans and the chickens were different . However, S . Enteritidis from chickens, and S . Braenderup and S . Agona from cows and pigs were clustered together in one group . There was no significant relatedness between NTS isolates from humans and those from animals, food or the environment in close contact to humans.

Commun Dis Public Health, 2001 Dec, 4(4), 300 - 4
Outbreak of Salmonella indiana associated with egg mayonnaise sandwiches at an acute NHS hospital; Mason BW et al.; An outbreak of Salmonella indiana infection in December 2000 affected 17 staff, relatives and patients at an acute NHS Hospital in Swansea . Epidemiological investigation identified egg mayonnaise sandwiches as the vehicle of infection . It was not possible to definitively determine the source of the infection or how the prepared sandwiches became contaminated . The most likely explanation was a pasteurisation failure of a batch of the egg roll used to make these sandwiches . Sandwiches are the most frequently identified vehicle of infection in foodborne outbreaks of salmonella infection in hospitals in England and Wales . The process of sandwich preparation has inherent risks because it involves considerable handling of food, which is consumed without further cooking . Care is required in all stages of preparation including the sourcing of materials used to produce the sandwiches . NHS Trusts should review their Hazard Analysis Critical Control Point plans for sandwich production.

Curr Mol Med, 2002 Jun, 2(4), 393 - 406
Immunity to systemic Salmonella infections; Mastroeni P; Salmonella infections are a serious public health problem in developing countries and represent a constant concern for the food industry . The severity and the outcome of a systemic Salmonella infection depends on the "virulence" of the bacteria, on the infectious dose as well as on the genetic makeup and immunological status of the host . The control of bacterial growth in the reticuloendothelial system (RES) in the early phases of a Salmonella infection relies on the NADPH oxidase-dependent anti-microbial functions of resident phagocytes and is controlled by the innate resistance gene Nramp1 . This early phase is followed by the suppression of Salmonella growth in the RES due to the onset of an adaptive host response . This response relies on the concerted action of a number of cytokines (TNFalpha, IFNgamma, IL12, IL18, and IL15), on the recruitment of inflammatory phagocytes in the tissues and on the activation of the recruited cells . Phagocytes control bacterial growth in this phase of the infection by producing reactive nitrogen intermediates (RNI) generated via the inducible nitric oxide synthase (iNOS) . Clearance of the bacteria from the RES at a later stage of the infection requires the CD28-dependent activation of CD4+ TCR-alphabeta T-cells and is controlled by MHC class II genes . Resistance to re-infection with virulent Salmonella micro-organisms requires the presence of Th1 type immunological memory and anti-Salmonella antibodies . Thus, the development of protective immunity to Salmonella infections relies on the cross-talk between the humoral and cellular branches of the immune system.

Rev Prat, 2002 May 15, 52(10), 1094 - 9
{Inflammatory and infectious aortitis}; Fiessinger JN et al.; Takayasu's disease is the most characteristic example of aortitis . Non-specific aortoarteritis is the only one with stenotic lesions of the aorta . Ischemic symptoms depend of the arterial lesions . Diagnosis is funded on topographic of arterial involvement . CT scan and ultrasound are the method of choice for the diagnosis and follow-up of patients . Compared to controls, patients with giant cell arteritis are 17 times more likely to develop thoracic aortic aneurysm . The risk of this location could justify a systematic research of an aortic involvement during the follow up of patients with temporal arteritis . Saccular aneurysms are an unusual manifestation of Behcet's disease but as in Horton's disease the poor prognosis impose a systematic evaluation . Syphilitic aortic is actually very rare, staphylococcus and salmonella are the main causes of mycotic aneurysms.

J Bacteriol, 2002 Aug, 184(15), 4197 - 204
Antigen 43-mediated autotransporter display, a versatile bacterial cell surface presentation system; Kjaergaard K et al.; Antigen 43 (Ag43), a self-recognizing outer membrane protein of Escherichia coli, has been converted into an efficient and versatile tool for surface display of foreign protein segments . Ag43 is an autotransporter protein characterized by the feature that all information required for transport to the outer membrane and secretion through the cell envelope is contained within the protein itself . Ag43 consists of two subunits (alpha and beta), where the beta-subunit forms an integral outer membrane translocator to which the alpha-subunit is noncovalently attached . The simplicity of the Ag43 system makes it ideally suited as a surface display scaffold . Here we demonstrate that the Ag43 alpha-module can accommodate and display correctly folded inserts and has the ability to display entire functional protein domains, exemplified by the FimH lectin domain . The presence of heterologous cysteine bridges does not interfere with surface display, and Ag43 chimeras are correctly processed into alpha- and beta-modules, offering optional and easy release of the chimeric alpha-subunits . Furthermore, Ag43 can be displayed in many gram-negative bacteria . This feature is exploited for display of our chimeras in an attenuated Salmonella strain.

J Bacteriol, 2002 Aug, 184(15), 4148 - 60
DNA-binding activities of the HilC and HilD virulence regulatory proteins of Salmonella enterica serovar Typhimurium; Olekhnovich IN et al.; The HilC and HilD proteins of Salmonella enterica serovar Typhimurium are members of the AraC/XylS family of transcription regulators . They are encoded on Salmonella pathogenicity island 1 (SPI1) and control expression of the hilA gene, which encodes the major transcriptional activator for many genes encoded on SPI1 and elsewhere that contribute to invasion of host cells . Gel electrophoretic shift and DNase footprinting assays revealed that purified HilC and HilD proteins can bind to multiple regions in the hilA and hilC promoters and to a single region in the hilD promoter . Although both HilC and -D proteins can bind to the same DNA regions, they showed different dependencies on the sequence and lengths of their DNA targets . To identify the binding-sequence specificity of HilC and HilD, a series of single base substitutions changing each position in a DNA fragment corresponding to positions -92 to -52 of the hilC promoter was tested for binding to HilC and HilD in a gel shift DNA-binding assay . This mutational analysis in combination with sequence alignments allowed deduction of consensus sequences for binding of both proteins . The consensus sequences overlap but differ so that HilC can bind to both types of sites but HilD only to one . The hilA and hilC promoters contain multiple binding sites of each type, whereas the hilD promoter contains a site that binds HilC but not HilD without additional binding elements . The HilC and HilD proteins had no major effect on transcription from the hilA or hilD promoters using purified proteins in vitro but changed the choice of promoter at hilC . These results are consistent with a model derived from analysis of lacZ fusions stating that HilC and HilD enhance hilA expression by counteracting a repressing activity.

J Bacteriol, 2002 Aug, 184(15), 4134 - 40
The 2-aminoethylphosphonate-specific transaminase of the 2-aminoethylphosphonate degradation pathway; Kim AD et al.; The 2-aminoethylphosphonate transaminase (AEPT; the phnW gene product) of the Salmonella enterica serovar Typhimurium 2-aminoethylphosphonate (AEP) degradation pathway catalyzes the reversible reaction of AEP and pyruvate to form phosphonoacetaldehyde (P-Ald) and L-alanine (L-Ala) . Here, we describe the purification and characterization of recombinant AEPT . pH rate profiles (log V(m) and log V(m)/K(m) versus pH) revealed a pH optimum of 8.5 . At pH 8.5, K(eq) is equal to 0.5 and the k(cat) values of the forward and reverse reactions are 7 and 9 s(-1), respectively . The K(m) for AEP is 1.11 +/- 0.03 mM; for pyruvate it is 0.15 +/- 0.02 mM, for P-Ald it is 0.09 +/- 0.01 mM, and for L-Ala it is 1.4 +/- 0.03 mM . Substrate specificity tests revealed a high degree of discrimination, indicating a singular physiological role for the transaminase in AEP degradation . The 40-kDa subunit of the homodimeric enzyme is homologous to other members of the pyridoxalphosphate-dependent amino acid transaminase superfamily . Catalytic residues conserved within well-characterized members are also conserved within the seven known AEPT sequences . Site-directed mutagenesis demonstrated the importance of three selected residues (Asp168, Lys194, and Arg340) in AEPT catalysis.

Cell Microbiol, 2002 Jul, 4(7), 435 - 46
Salmonella enterica serovar Typhimurium effector SigD/SopB is membrane-associated and ubiquitinated inside host cells; Marcus SL et al.; SigD/SopB is an effector protein translocated into host cells by one of the type III secretion systems of Salmonella enterica serovar Typhimurium (serovar Typhimurium) . It is an inositol phosphatase that has activity towards several inositol phospholipids in vitro, including phosphatidylinositol 3,4,5- triphosphate . SigD activates Akt in epithelial cells and indirectly activates Cdc42 through one of its products, inositol 1,4,5,6-tetrakisphosphate . As phospholipid targets of SigD activity are localized to host cell membranes, we sought to investigate the intracellular localization of translocated SigD . We show here that SigD is a membrane-associated protein that is ubiquitinated inside host cells . SigD was extracted from host cell membranes with a high pH buffer but not by high salt . Fractionation and deletion analysis using transfected SigD-green fluorescent protein fusions revealed that amino acid residues 117-167 of SigD are essential for membrane association, and that a fragment containing residues 29-116 was ubiquitinated . This is the first direct evidence of a bacterial effector protein being ubiquitinated . Treatment of cells with the proteasome inhibitor MG-132 revealed that, unlike the host cell protein inhibitor of nuclear factor kappa B (IkappaBalpha), SigD does not appear to be rapidly degraded by the proteasome . We speculate that ubiquitination serves to downregulate SigD activity by an alternative mechanism, such as by targeting it for lysosomal degradation.

J Biol Chem, 2002 Oct 25, 277(43), 41120 - 7 Epub 2002 Jul 05.
Capture of a labile substrate by expulsion of water molecules from the active site of nicotinate mononucleotide:5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) from Salmonella enterica; Cheong CG et al.; Nicotinate mononucleotide (NaMN):5,6-dimethylbenzimidazole (DMB) phosphoribosyltransferase (CobT) from Salmonella enterica plays a central role in the synthesis of alpha-ribazole-5'-phosphate, an intermediate for the lower ligand of cobalamin . In earlier studies it proved difficult to obtain the structure of CobT bound to NaMN because it is hydrolyzed in the crystal lattice in the absence of the second substrate DMB . In an effort to map the reaction pathway of this enzyme, NaMN was captured in the active site with the substrate analogs 4,5-dimethyl-1,2-phenylenediamine, 4-methylcatechol, indole, 3,4-dimethylaniline, 2,5-dimethylaniline, 3,4-dimethylphenol, and 2-amino-p-cresol . Structures of these complexes reveal that they exclude water molecules responsible for the hydrolysis from the active site . These structures, together with the early complexes with alpha-ribazole-5'-phosphate and DMB, provide a complete description of the reaction pathway . They demonstrate that the nicotinate moiety and phosphate do not appear to move significantly between reactants and products but that the aromatic base and ribose moiety each move approximately 1.2 A toward each other in the transformation . This study also reveals that, like many other nucleotide binding proteins, coordination of DMB is accompanied by a disorder-order transition in a surface loop . The structure of apo-CobT is also reported.

Lett Appl Microbiol, 2002, 35(2), 146 - 52
Serotyping and RAPD profiles of Salmonella enterica isolates from Mauritius; Khoodoo MH et al.; AIMS: The genus Salmonella is a common agent of gastroenteritis in Mauritius, generating more cases of the disease during summer than during winter . The aims of this study were to assess the genetic diversity of isolates of Salmonella enterica by RAPD fingerprinting, and to establish the relationship between human and chicken isolates . METHODS: Twenty-six isolates were obtained from hospital laboratories and commercial poultry producers locally . RESULTS: The RAPD profiles, biochemical and serological analyses showed that two of the chicken isolates were mistakenly identified as Salmonella . The genetic diversity of the remaining 24 isolates (five chicken and 19 human), confirmed as Salmonella, was analysed using four arbitrary primers, OPA-10, OPR-03, OPI-06 and OPJ-09, chosen from an initial set of 10 decamers . Seventy RAPD markers were generated in four individual DNA profiles . SIGNIFICANCE AND IMPACT OF THE STUDY: Cluster analysis (UPGMA) performed using the NTSYS-pc V 1.8 computer software, confirmed that some strains of Salmonella isolated from chicken were genetically similar to those isolated from humans . Furthermore, a 1 kbp band amplified using primer OPA-10 was specific for the Salmonella genus as it was not amplified in any of the control bacteria.

Environ Sci Technol, 2002 Jun 15, 36(12), 2754 - 9
PCR detection of specific pathogens in water: a risk-based analysis; Loge FJ et al.; The relative concentration of pathogens in water samples collected from storm drains and adjacent surfaces was evaluated using established PCR-based protocols . Out of the 58 samples collected from 21 different storm drains, 22% were PCR positive for Escherichia coli ETEC, Salmonella, or adenovirus . The risk of swimming related illnesses associated with detection of E . coli ETEC and Salmonella ranged from 0.39 to 30:100 000 and 0.3-25:1000, respectively . The detection limit corresponding to a negative-PCR result was evaluated in reference to water quality standards developed using a risk-based approach that integrates human dose-response data with acceptable levels of risk promulgated by the U.S . EPA for recreational contact . The percent of samples with an acceptable detection limit ranged from 0% for Giardia lamblia and Shigella to 100% for E . coli ETEC . The principal factor influencing the detection limit of G . lamblia and Shigella was sample volume . The principal factor influencing the detection limit of the remaining bacteria and protozoa, including E . coli O157:H7, Salmonella, and Cryptosporidium parvum, was the presence of inhibitory compounds in the purified nucleic acid extracts . Both recovery and inhibition adversely impacted the detection limit of viruses . Ambient water quality standards based on the occurrence of specific pathogens enumerated with PCR-based assays could serve as a method of evaluating the biological quality of water but only after significant improvements in filtration and purification protocols . The risk-based methodology developed in this study can be used to evaluate future improvements in filtration and purification protocols.

J Microbiol Immunol Infect, 2002 Jun, 35(2), 94 - 8
Duration of antimicrobial therapy for non-typhoid Salmonella bacteremia in healthy children; Yen MH et al.; Medical records of patients less than 17 years of age with positive blood culture for non-typhoid Salmonella from June 1996 through December 1998 at the Chang Gung Children's Hospital were collected . Patients were categorized into 3 groups according to the duration of effective antibiotic therapy they received . Group 1 received effective antibiotic therapy for less than 7 days; Group 2 for 7 to 9 days; and Group 3 for 10 days or more . Information on clinical presentations, laboratory data, and outcome were collected and analyzed . A total of 59 children were eligible, with 21 in Group 1, 17 in Group 2, and 21 in Group 3 . Demographic data were similar among the 3 groups . No significant difference was found in the clinical symptoms and laboratory data among these groups, including white blood cell count, immature to total ratio of white blood cell, and serum C-reactive protein level . Salmonella group B (n = 37) were the most common isolates, followed by group D (n = 9), group C2 (n = 8), cholerasuis (n = 4), and C1 (n = 2) . Third-generation cephalosporins were the final antibiotic therapy in most (90%) patients, and no isolates showed resistance to these agents in this study . No focal suppurative complications were noted at the initial evaluation and in the 1-year period after treatment . No clinical recurrent diseases were noted during a follow-up period of at least 1 year . Results suggest that for otherwise healthy children with non-typhoid Salmonella bacteremia, less than 10 days of antibiotics therapy could be adequate if they are more than 1 year old and no focal extra-intestinal infection is noted in the initial evaluation.

J Microbiol Immunol Infect, 2002 Jun, 35(2), 78 - 84
Multidrug-resistant non-typhoid Salmonella infections in a medical center; Lee CY et al.; Due to the high incidence of antimicrobial-resistant Salmonella in Taiwan, the emergence of multidrug-resistant Salmonella has become of particular concern . This retrospective study assessed the clinical features of patients with multidrug-resistant Salmonella treated from January 1998 through June 2000 . A total of 201 children and 33 adults with multidrug-resistant Salmonella infections treated during a 2.5-year period were included . Sixty-percent of these patients had used antibiotics before multidrug-resistant Salmonella infection developed . The incidence of extra-intestinal infections was higher in adults (51.4%) than in children (4.9%) . Infection with an invasive serotype of Salmonella, such as Salmonella choleraesuis, and host factors appeared to be predisposing factors for bacteremia or extra-intestinal infections . None of the patients had mortality attributable to multidrug-resistant salmonellosis . The increasing rate of resistance to third-generation cephalosporins and fluoroquinolones and the high multidrug-resistant rate of S . choleraesuis found in this study indicate the importance of judicious use of antimicrobial agents in both humans and animals to reduce the selection and spread of resistant strains.

J Org Chem, 2002 Jul 12, 67(14), 4640 - 6
Synthesis of the Salmonella type E(1) core trisaccharide as a probe for the generality of 1-(benzenesulfinyl)piperidine/triflic anhydride combination for glycosidic bond formation from thioglycosides; Crich D et al.; A synthesis of a chromogenic glycoside of the Salmonella anatum group E(1) core trisaccharide is presented in which all three glycosidic bonds, a 1,2-cis-equatorial, a 1,2-trans-axial, and a 1,2-trans-equatorial linkage representing three of the four main classes of glycosidic bond, are formed with thioglycoside donors activated under a single set of conditions by the combination of 1-(benzenesulfinyl)piperidine and trifluoromethanesulfonic anhydride . 2,3-O-Carbonyl- and 2,3-O-isopropylidene-alpha-L-rhamnopyranosyl thioglycosides are found to be highly alpha-selective rhamnosyl donors under these conditions.

Shock, 2002 Jul, 18(1), 93 - 6
Peroxynitrite enhances the ability of Salmonella dublin to invade T84 monolayers; Cornish AS et al.; In the intestine, epithelial cells continually produce and secrete low levels of nitric oxide (NO) . Salmonella sp . invade epithelium by responding to environmental stimuli . The aims of this study were to determine the effect of reactive nitrogen intermediates (RNIs) on S . dublin and S . typhimurium growth and invasion of T84 epithelial monolayers . Intracellular NO formation was inhibited by 7-nitroindazole (7-NI) or N(G)-monomethyl-L-arginine, monoacetate (L-NMMA); extracellular NO and peroxynitrite were scavenged with ferro-hemoglobin or urate . The effect of authentic peroxynitrite (ONOO-); 3-morpholino-sydnonimine (SIN-1), which releases ONOO- via NO and superoxide; spermine NONOate, which releases only NO; or superoxide generated by xanthine oxidase and pterin on S . dublin and S . typhimurium growth and invasion were examined . Inhibition of NO synthesis and scavenging of extracellular NO or peroxynitrite reduced S . dublin invasion into T84 monolayers and enhanced bacterial growth . Pre-exposure of S . dublin to ONOO- and SIN-1 increased subsequent bacterial invasion into T84 monolayers . Conversely, exposure of bacteria to spermine NONOate or superoxide did not affect S . dublin invasion . In contrast, S . typhimurium invasion was not affected by pre-treatment with NO donors . In conclusion, exposure of S . dublin to ONOO- enhances the ability of the bacteria to invade epithelial cells . These results suggest that luminal ONOO- may have a novel role as an extracellular signal between invasive bacteria and epithelial cells.

Trop Anim Health Prod, 2002 May, 34(3), 195 - 204
Comparative pathogenesis of experimental infections with Salmonella gallinarum in local and commercial chickens; Mdegela RH et al.; The pathogenicity of a virulent strain of Salmonella gallinarum was studied in local chickens and commercial layers . Sixty 4-month-old chickens were used . Of these, 50 chickens were orally infected with S . gallinarum, comprising 25 commercial layers and 25 local chickens . Five chickens in each group were used as uninfected negative controls . The clinical signs and pathological features of acute, subacute and chronic fowl typhoid were observed in both groups . Chickens in both groups seroconverted, but the antibody titre was significantly higher (p < 0.001) in the commercial layers . The antibody titre remained high to the end of the experiment in all the surviving chickens . Only one commercial layer chicken died during the course of the experiment . The PCV decreased significantly (p < 0.001) in the infected chickens of both groups as compared to the controls . The viable cell count of S . gallinarum in the liver and spleen reached a maximum on day 9 after infection in both groups . However, there was a significantly higher cell count (p < 0.05) in the commercial layers . The severity of the disease appeared to be slightly greater in the commercial layers, although the susceptibility was similar in both groups . It was concluded that, under experimental conditions, local chickens are just as susceptible to S . gallinarum infection as are commercial layers.

Clin Diagn Lab Immunol, 2002 Jul, 9(4), 938 - 41
Widal test in diagnosis of typhoid fever in Turkey; Willke A et al.; We studied the value of the Widal tube agglutination test for the diagnosis of typhoid fever . The subjects were all adults >18 years of age and were divided into four groups: (i) 317 healthy blood donor controls, (ii) 31 bacteriologically confirmed patients with Salmonella enterica serotype Typhi, (iii) 21 patients with a clinical diagnosis of typhoid fever, and (iv) 41 febrile nontyphoid patients . Blood donor controls were screened with a slide agglutination test for the Salmonella enterica serotype Typhi O and H antigens, and positives were then tested with the Widal test . Acute- and convalescent-phase sera from patients in groups 2, 3, and 4 were obtained 7 to 10 days apart and tested by the Widal test . Using a cutoff of >or = 1/200 for the O antigen test performed on acute-phase serum gave a sensitivity of 52% and a specificity of 88% with a positive predictive value (PPV) of 76% and a negative predictive value (NPV) of 71% . This increased to 90% sensitivity and specificity with a PPV of 88% and an NPV of 93% when the convalescent-phase serum was tested . We concluded that O and H agglutinin titers of > or = 1/200 are of diagnostic significance . The Widal test is easy, inexpensive, and relatively noninvasive . It can be of diagnostic value when blood cultures are not available or practical . The results must be interpreted cautiously because of the low sensitivity of the test . The Widal test done on convalescent-phase serum gave more-reliable results with higher specificity and sensitivity.

Biosci Biotechnol Biochem, 2002 May, 66(5), 1009 - 14
Rutin-enhanced antibacterial activities of flavonoids against Bacillus cereus and Salmonella enteritidis; Arima H et al.; The antibacterial activities of flavonoids were found by the paper disk method to be enhanced by combining or mixing them . The combinations of quercetin and quercitrin, quercetin and morin, and quercetin and rutin were much more active than either flavonoid alone . Although rutin did not show activity in itself, the antibacterial activities of quercetin and morin were enhanced in the presence of rutin . The antibacterial activities of flavonoids, in combination with morin and rutin, were evaluated, based on the minimum inhibition concentration (MIC) in a liquid culture, by using Salmonella enteritidis and Bacillus cereus as the test bacteria . The activities of galangin, kaempherol, myricetin and fisetin were each enhanced in the presence of rutin when S . enteritidis was used as the test bacterium . The MIC value for kaempherol was markedly decreased by the addition of rutin . Morin inhibited DNA synthesis, and this effect was promoted by rutin at a concentration of 25 microg/ml.

J Food Prot, 2002 Jun, 65(6), 937 - 47
Testing for Salmonella in raw meat and poultry products collected at federally inspected establishments in the United States, 1998 through 2000; Rose BE et al.; The Food Safety and Inspection Service (FSIS) issued Pathogen Reduction; Hazard Analysis and Critical Control Point (HACCP) Systems; Final Rule (the PR/HACCP rule) on 25 July 1996 . To verify that industry PR/HACCP systems are effective in controlling the contamination of raw meat and poultry products with human disease-causing bacteria, this rule sets product-specific Salmonella performance standards that must be met by slaughter establishments and establishments producing raw ground products . These performance standards are based on the prevalence of Salmonella as determined from the FSIS's nationwide microbial baseline studies and are expressed in terms of the maximum number of Salmonella-positive samples that are allowed in a given sample set . From 26 January 1998 through 31 December 2000, federal inspectors collected 98,204 samples and 1,502 completed sample sets for Salmonella analysis from large, small, and very small establishments that produced at least one of seven raw meat and poultry products: broilers, market hogs, cows and bulls, steers and heifers, ground beef, ground chicken, and ground turkey . Salmonella prevalence in most of the product categories was lower after the implementation of PR/HACCP than in pre-PR/HACCP baseline studies and surveys conducted by the FSIS . The results of 3 years of testing at establishments of all sizes combined show that >80% of the sample sets met the following Salmonella prevalence performance standards: 20.0% for broilers, 8.7% for market hogs, 2.7% for cows and bulls, 1.0% for steers and heifers, 7.5% for ground beef, 44.6% for ground chicken, and 49.9% for ground turkey . The decreased Salmonella prevalences may partly reflect industry improvements, such as improved process control, incorporation of antimicrobial interventions, and increased microbial-process control monitoring, in conjunction with PR/HACCP implementation.

J Food Prot, 2002 Jun, 65(6), 1038 - 40
Acquisition of antibiotic resistance plasmids by enterohemorrhagic Escherichia coli O157:H7 within rumen fluid; Mizan S et al.; The emergence of antibiotic resistance among important foodborne pathogens like Escherichia coli O157:H7 has become an important issue with regard to food safety . In contrast to the case for Salmonella, antibiotic resistance has been slow in its development in E . coli O157:H7 despite the presence of mobile antibiotic resistance genes in other E . coli organisms that inhabit the same animal host . We set out to determine if rumen fluid influences the transfer of plasmid-mediated, antibiotic resistance to E . coli O157:H7 . A commensal E . coli strain from a dairy cow was transformed with conjugative R plasmids and served as the donor in matings with naladixic acid-resistant E . coli O157:H7 . R plasmids were transferred from the donor E . coli strain to E . coli O157:H7 in both Luria-Bertani (LB) broth and rumen fluid . R plasmids were transferred at a higher frequency to E . coli O157:H7 during 6 h of incubation in rumen fluid at rates comparable to those in LB broth, indicating that conditions in rumen fluid favor the transfer of the plasmids to E . coli O157 . This finding suggests that the cow's rumen is a favorable environment for the genetic exchange of plasmids between microflora and resident E . coli O157:H7 in the bovine host.

J Food Prot, 2002 Jun, 65(6), 1005 - 7
Serotyping and ribotyping of Salmonella using restriction enzyme PvuII; Bailey JS et al.; The subtyping and identification of bacterial pathogens throughout food processing and production chains is useful to the new hazard analysis critical control point-based food safety plans . Traditional manual serotyping remains the primary means of subtyping Salmonella isolates . Molecular biology techniques, however, offer the promise of more rapid and sensitive subtyping of Salmonella . This study evaluates the potential of restriction enzyme PvuII, followed by probing with the rRNA operon from Escherichia coli, to generate serotype-specific DNA fingerprints . A total of 32 identified serotypes were found with an overall agreement in 208 of the 259 (80%) isolates tested between U.S . Department of Agriculture serotype identification and riboprint serotype identification . Many of the isolates that did not correlate were serotype identified as Salmonella Montevideo, which indicates that for this serotype, there are multiple ribotypes . When Salmonella Montevideo isolates were not included, the ribotype identification agreed with serotyping in 207 of the 231 (90%) isolates . The primary outcome of any ribotyping procedure is to give distinct ribotype patterns . This extensive poultry epidemiological study demonstrates that, in addition to ribotype patterns, the identification of isolates to known serotypes provides the investigator with additional information that can be more useful than traditional epidemiology and isolate identification studies.

Rev Med Chir Soc Med Nat Iasi, 2001 Jul-Sep, 105(3), 536 - 40
{Clinical and biological study of acute diarrhea with mixed etiology in 48 patients}; Luca C et al.; OBJECTIVES: The study of incidence, clinical manifestation and treatment of acute diarrhea with mixed etiology . MATERIAL AND METHOD: Study of 48 patients with acute diarrhea with mixed etiology admitted in the Hospital of Infectious Diseases of Iasi during 1995-1998 . RESULTS: 12 cases (24%) were mixed bacterial infections with the following microorganisms associations: Salmonella + Shigella (10 cazuri); Salmonella + Yersinia enterocolitica (1 case); Salmonella + Rotavirus (1 case) . 16 cases (44%) had mixed digestive infections with parasites, in double or triple associations: Giardia intestinalis + Ascaris lumbricoides (10 cases); Giardia intestinalis + Ascaris lumbricoides + Entamoeba coli (1 case); Giardia intestinalis + Enterobius vermicularis (3 cases); Ascaris lumbricoides + Trichiuris trichiura (2 cases) . The rest of 20 cases presented mixed infections with bacteria and parasites: Salmonella + Rotavirus + Giardia (2 cases), Salmonella + Shigella + Giardia intestinalis or Ascaris lumbricoides (6 cases), Salmonella + Giardia intestinalis (8 cases); Salmonella + Entamoeba coli (3 cases); Shigella + Trichiura trichiuris + Entamoeba coli (1 case) . The majority was male patients from rural areas with age between 5 month and 56 years, the majority being children, 4 cases were found in immunosupressed patients . The clinical symptomatology was dominated by diarrheal syndrome (100%) and the diagnosis was established by clinical characters and confirmed by coproculture and parasitologic exam . The ethiological therapy was guided by antibiogram, in the majority of cases we used fluorochinolones (associated with ceftriaxone in severe cases), together with antiparasitic medications . CONCLUSIONS: In this study predominated the bacterial and parasitic infections, most frequently being isolated Salmonella, Shigella and Giardia intestinalis; the therapy associated fluorochinolones with antiparasitic medication.

Rev Med Chir Soc Med Nat Iasi, 2001 Jan-Mar, 105(1), 133 - 5
Study of outer membrane proteins (OMPS) and their role in co-modulation of resistance in non typhoidic Salmonella strains isolated in Iaşi; Filip R et al.; OBJECTIVES: To characterize the OMP profile and to study the possible interference with other resistance determinants . MATERIAL AND METHODS: 16 non-typhoidic Salmonella strains, isolated in 1999 from stools of pediatric patients, were selected according to their resistance phenotype: resistance to Ampicillin (AMP), Amoxycillin/Clavulanic Acid (AMC), and third generation cephalosporins: Ceftriaxone (CRO) and Ceftazidime (CAZ) . Identification and sensitivity testing were done by DADE MicroScan System . beta-Lactamases were characterized by isoelectric focusing (IEF) with preformed minigelss . OMPs were studied on membrane preparations on SDS-urea gels . RESULTS: Isoelectric points: Majority of the isolates had the association 5.4 +/- 7.6 (3/16) or 5.4 + 8.2 (6/16) . The second beta-lactamase has the capacity to hydrolyse CAZ . We found three different patterns of OMPs: I: 30, 29 and 25 kDa; II: 30, 26 and 24 kDa; III: 30 and 25 kDa . We couldn't find any correlation between the OMPs profile and resistance phenotype, showing that the beta-lactamase production is the only resistant determinant . CONCLUSIONS: The study shows the high frequency of extended-spectrum beta-lactamases (ES beta LA) amongst the non-typhoidic Salmonella; association of TEM type and ES beta LA enzymes diminishes considerably the therapeutic resources: inhibitor associated combinations are non effective . In non-typhoidic Salmonella, porins seems to have no influence in co-modulation of resistance.

J Biol Chem, 2002 Sep 13, 277(37), 34247 - 53 Epub 2002 Jun 28.
Pore formation and function of phosphoporin PhoE of Escherichia coli are determined by the core sugar moiety of lipopolysaccharide; Hagge SO et al.; The lipid matrix of the outer membrane of Gram-negative bacteria is an asymmetric bilayer composed of a phospholipid inner leaflet and a lipopolysaccharide outer leaflet . Incorporated into this lipid matrix are, among other macromolecules, the porins, which have a sieve-like function for the transport or exclusion of hydrophilic substances . It is known that a reduced amount of porins is found in the outer membrane of rough mutants as compared with wild-type bacteria . This observation was discussed to be caused by a reduced number of insertion sites in the former . We performed electrical measurements on reconstituted planar bilayers composed of lipopolysaccharide on one side and a phospholipid mixture on the other side using lipopolysaccharide from various rough mutant strains of Salmonella enterica serovar Minnesota . We found that pore formation by PhoE trimers that were added to the phospholipid side of the bilayers increased with the increasing length of the lipopolysaccharide core sugar moiety . These results allow us to conclude that the length of the sugar moiety of lipopolysaccharide is the parameter governing pore formation and that no particular insertion sites are required . Furthermore, we found that the voltage gating of the porin channels is strongly dependent on the composition of the lipid matrix.

Rev Med Chir Soc Med Nat Iasi, 2000 Apr-Jun, 104(2), 109 - 12
Resistance mechanism for a number of non-typhoidic Salmonella strains isolated in Iaşi, Romania; Filip R et al.; The aim of this study was to find a possible explanation for the resistance pattern of the selected strains and to evaluate the impact in case of isolating such strains . During the period February-March 1998, in the Pediatric Hospital "Sf . Maria" from Iasi, Romania, 12 non-typhoidic Salmonella strains, non-duplicates were isolated from stools of newborns and, in one case, from mother as well . Identification was done by standard methods, and sensitivity testing by disk diffusion method, against the following antimicrobials: Ampicillin (A), Amoxycilin/Clavulanic Acid (AMC), Tetracycline (T), Streptomycin (S), Cloramphenicol (C), Nalidixic Acid (NA), Ciprofloxacin (CIP), Cephalotin (KF), Cefuroxime (CXM), Ceftriaxone (CRO), Cefotaxime (CTX), Ceftazidime (CAZ), Aztreonam (AZT), Imipenem (IPM), Amikacin (AK) . All strains showed resistance to: A, AMC, T, S, C, NA, CRO, CAZ, CXM, CTX, KF except one strain, CTX and CRO sensitive . The possible explanation is the production of an extended-spectrum beta-lactamase (ESbLA), detected by microbiological methods (Masuda and clover-leaf) . Resistance transfer was realised by using the previously described method . In conjugation experiments we have obtained only one transconjugant, identified as E . coli, that has acquired all resistance determinants . This report highlights on the isolation of multiresistant non-typhoidic Salmonella strains in hospitalised patients without previous antibiotic treatment and possibility of detecting such strains by being aware of the correlation: resistance phenotype-resistance mechanism.

Exp Physiol, 2002 May, 87(3), 391 - 9
Route of administration differentially affects fevers induced by Gram-negative and Gram-positive pyrogens in rabbits; Cartmell T et al.; We have investigated the febrile responses of New Zealand White rabbits to a Gram-negative pyrogen (bacterial lipopolysaccharide (LPS) from Salmonella typhosa), commonly associated with systemic infection, and a Gram-positive pyrogen (Staphylococcus aureus), more frequently associated with superficial soft tissue infection, each administered via one of four different routes (intravenous, intramuscular, subcutaneous or intraperitoneal) at each of three different doses (LPS: 0.1, 1 and 10 microg kg(-1); S . aureus: 1.5 x 10(7), 1.5 x 10(8) and 1.5 x 10(9) cell walls kg(-1)) . Intravenous administration of LPS evoked rapid, dose-dependent biphasic fever . Injection of LPS by the other routes also evoked dose-dependent fever . However, these fevers were monophasic, had increased latency of onset, and were of lower amplitude . It is important to note that a dose of approximately 10 and 100 times that of the standard intravenous dose was required to produce a similar peak rise in temperature when administered subcutaneously and intraperitoneally, respectively . Intravenous injection of the highest dose of S . aureus evoked dose-dependent biphasic fever, with short latency of onset, which was very similar to that induced by intravenous LPS . At lower doses, intravenous S . aureus induced monophasic fever . No fever occurred when the same doses of S . aureus were administered by any other route . We conclude that any of the four routes may be used for the study of LPS-induced fever, provided that the doses are adjusted . However, studies of S . aureus-induced fever, and detection of contamination with either pyrogen, requires intravenous injection.

Science, 2002 Jun 28, 296(5577), 2376 - 9
50 million years of genomic stasis in endosymbiotic bacteria; Tamas I et al.; Comparison of two fully sequenced genomes of Buchnera aphidicola, the obligate endosymbionts of aphids, reveals the most extreme genome stability to date: no chromosome rearrangements or gene acquisitions have occurred in the past 50 to 70 million years, despite substantial sequence evolution and the inactivation and loss of individual genes . In contrast, the genomes of their closest free-living relatives, Escherichia coli and Salmonella spp., are more than 2000-fold more labile in content and gene order . The genomic stasis of B . aphidicola, likely attributable to the loss of phages, repeated sequences, and recA, indicates that B . aphidicola is no longer a source of ecological innovation for its hosts.

J Clin Microbiol, 2002 Jul, 40(7), 2662 - 5
Multidrug and broad-spectrum cephalosporin resistance among Salmonella enterica serotype enteritidis clinical isolates in southern Italy; Villa L et al.; From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins . Five isolates produced SHV-12, and one isolate encoded a class C beta-lactamase . The bla(SHV-12) gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.

J Clin Microbiol, 2002 Jul, 40(7), 2498 - 503
Genetic diversity of clinical and environmental strains of Salmonella enterica serotype Weltevreden isolated in Malaysia; Thong KL et al.; The incidence of food-borne salmonellosis due to Salmonella enterica serotype Weltevreden is reported to be on the increase in Malaysia . The pulsed-field gel electrophoresis (PFGE) subtyping method was used to assess the extent of genetic diversity and clonality of Salmonella serotype Weltevreden strains from humans and the environment . PFGE of XbaI-digested chromosomal DNA from 95 strains of Salmonella serotype Weltevreden gave 39 distinct profiles with a wide range of Dice coefficients (0.27 to 1.00), indicating that PFGE is very discriminative and that multiple clones of Salmonella serotype Weltevreden exist among clinical and environmental isolates . Strains of one dominant pulsotype (pulsotype X1/X2) appeared to be endemic in this region, as they were consistently recovered from humans with salmonellosis between 1996 and 2001 and from raw vegetables . In addition, the sharing of similar PFGE profiles among isolates from humans, vegetables, and beef provides indirect evidence of the possible transmission of salmonellosis from contaminated raw vegetables and meat to humans . Furthermore, the recurrence of PFGE profile X21 among isolates found in samples of vegetables from one wet market indicated the persistence of this clone . The environment in the wet markets may represent a major source of cross-contamination of vegetables with Salmonella serotype Weltevreden . Antibiotic sensitivity tests showed that the clinical isolates of Salmonella serotype Weltevreden remained drug sensitive but that the vegetable isolates were resistant to at least two antibiotics . To the best of our knowledge, this is the first study to compare clinical and environmental isolates of Salmonella serotype Weltevreden in Malaysia.

J Clin Microbiol, 2002 Jul, 40(7), 2346 - 51
Characterization of Salmonella serovars by PCR-single-strand conformation polymorphism analysis; Nair S et al.; PCR-restriction fragment length polymorphism (PCR-RFLP) and PCR-single-strand conformation polymorphism (PCR-SSCP) analyses were carried out on the 1.6-kb groEL gene from 41 strains of 10 different Salmonella serovars . Three HaeIII RFLP profiles were recognized, but no discrimination between the serovars could be achieved by this technique . However, PCR-SSCP analysis of the groEL genes of various Salmonella serovars produced 14 SSCP profiles, indicating the potential of this technique to differentiate different Salmonella serovars (interserovar differentiation) . Moreover, PCR-SSCP could differentiate strains within a subset of serovars (intraserovar discrimination), as three SSCP profiles were produced for the 11 Salmonella enterica serovar Enteritidis strains, and two SSCP profiles were generated for the 7 S . enterica serovar Infantis and five S . enterica serovar Newport strains . PCR-SSCP has the potential to complement classical typing methods such as serotyping and phage typing for the typing of Salmonella serovars due to its rapidity, simplicity, and typeability.

Appl Environ Microbiol, 2002 Jul, 68(7), 3614 - 21
Fitness of Salmonella enterica serovar Thompson in the cilantro phyllosphere; Brandl MT et al.; The epiphytic fitness of Salmonella enterica was assessed on cilantro plants by using a strain of S . enterica serovar Thompson that was linked to an outbreak resulting from cilantro . Salmonella serovar Thompson had the ability to colonize the surface of cilantro leaves, where it was detected by confocal laser scanning microscopy (CLSM) at high densities on the veins and in natural lesions . The population sizes of two common colonizers of plant surfaces, Pantoea agglomerans and Pseudomonas chlororaphis, were 10-fold higher than that of the human pathogen on cilantro incubated at 22 degrees C . However, Salmonella serovar Thompson achieved significantly higher population levels and accounted for a higher proportion of the total culturable bacterial flora on cilantro leaves when the plants were incubated at warm temperatures, such as 30 degrees C, after inoculation, indicating that the higher growth rates exhibited by Salmonella serovar Thompson at warm temperatures may increase the competitiveness of this organism in the phyllosphere . The tolerance of Salmonella serovar Thompson to dry conditions on plants at 60% relative humidity was at least equal to that of P . agglomerans and P . chlororaphis . Moreover, after exposure to low humidity on cilantro, Salmonella serovar Thompson recovered under high humidity to achieve its maximum population size in the cilantro phyllosphere . Visualization by CLSM of green fluorescent protein-tagged Salmonella serovar Thompson and dsRed-tagged P . agglomerans inoculated onto cilantro revealed that the human pathogen and the bacterial epiphyte formed large heterogeneous aggregates on the leaf surface . Our studies support the hypothesis that preharvest contamination of crops by S . enterica plays a role in outbreaks linked to fresh fruits and vegetables.

Mutat Res, 2002 Jul, 511(3), 191 - 206
Carcinogenicity of the aromatic amines: from structure-activity relationships to mechanisms of action and risk assessment; Benigni R et al.; Aromatic amines represent one of the most important classes of industrial and environmental chemicals: many of them have been reported to be powerful carcinogens and mutagens, and/or hemotoxicants . Their toxicity has been studied also with quantitative structure-activity relationship (QSAR) methods: these studies are potentially suitable for investigating mechanisms of action and for estimating the toxicity of compounds lacking experimental determinations . In this paper, we first summarized the QSAR models for the rodent carcinogenicity of the aromatic amines . The gradation of potency of the carcinogenic amines depended firstly on their hydrophobicity, and secondly on electronic (reactivity, propensity to be metabolically transformed) and steric properties . On the contrary, the difference between carcinogenic and non-carcinogenic aromatic amines depended mainly on electronic and steric properties . These QSARs can be used directly for estimating the carcinogenicity of aromatic amines . A two-step prediction is possible: (1) estimation of yes/no activity; (2) if the answer from step 1 is yes, then prediction of the degree of potency . The QSARs for rodent carcinogenicity were put in a wider context by comparing them with those for: (a) Salmonella mutagenicity; (b) general toxicity; (c) enzymatic reactions; (d) physical-chemical reactions . This comparative QSAR exercise generated a coherent global picture of the action mechanisms of the aromatic amines . The QSARs for carcinogenicity were similar to those for Salmonella mutagenicity, thus pointing to a similar mechanism of action . On the contrary, the general toxicity QSARs (both in vitro and in vivo systems) were mostly based on hydrophobicity, pointing to an aspecific mechanism of action much simpler than that for carcinogenicity and mutagenicity . The oxidation of the amines (first step in the main metabolic pathway leading to carcinogenic and mutagenic species) had identical QSARs in both enzymatic and physical-chemical systems, thus providing evidence for the link between simple chemical reactions and those in biological systems . The results show that it is possible to generate mechanistically and statistically sound QSAR models for rodent carcinogenicity, and indirectly that the rodent bioassay is a reliable source of good quality data.

Curr Opin Immunol, 2002 Aug, 14(4), 437 - 43
The role of dendritic cells during Salmonella infection; Wick MJ; One type of phagocytic antigen-presenting cell (APC) - the dendritic cell (DC) - may have specialized functions during infection with the bacterium Salmonella, including a possible role in transporting Salmonella across the intestinal barrier . In addition, changes in the number, localization and cytokine production of CD8alpha+, CD8alpha-CD4+ and CD8alpha-CD4- DC subsets occur during infection . DCs function in stimulating bacteria-specific T cells by direct presentation of Salmonella antigens and as bystander APCs . Studying the function of DCs during Salmonella infection provides insight into the capacity of these sophisticated APCs, which are a key link between innate and adaptive immunity, to initiate and modulate the immune response to a bacterial infection.

Eur J Epidemiol, 2001, 17(8), 751 - 5
Epidemiology of antibiotic resistance of human nontyphoidal salmonellae in Greece during an 8-year period (1990-1997); Velonakis EN et al.; The susceptibility patterns of 1027 nontyphoidal Salmonella strains of human origin, isolated in Greece between 1990 and 1997, were determined by broth microdilution . From 1990 to 1995, the overall incindence of resistance for both Salmonella enteritidis and S . typhimurium increased . From 1996 onwards, a decrease was observed, which was more evident for S . enteritidis . Regarding the other examined serotypes a substantial proportion of resistant isolates was found only for S . Virhow and S.

J AOAC Int, 2002 May-Jun, 85(3), 609 - 25
Evaluation of VIDas immuno-concentration Salmonella/VIDAS salmonella immunoassay method for detection of Salmonella in selected foods: collaborative study; Lepper WA et al.; The VIDAS Immuno-concentration Salmonella ICS)/VIDAS Salmonella (SLM) immunoassay method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study . Thirty-two laboratories participated in the evaluation . Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey . The 2 methods were in agreement for 1,266 of the 1,440 samples . Of the 174 samples not in agreement, 69 were VIDAS CS/SLM-positive and BAM/AOAC-negative and 105 were VIDAS ICS/SLM-negative and BAM/AOAC-positive.

J AOAC Int, 2002 May-Jun, 85(3), 593 - 608
Salmonella in selected foods by VIDAS immuno-concentration Salmonella plus selective plate method (Hektoen enteric, xylose lysine desoxycholate, bismuth sulfite): collaborative study; Lepper WA et al.; The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, xylose lysine desoxycholate, bismuth sulfite) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study . Thirty-two laboratories participated in the evaluation . Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey . The 2 methods were in agreement for 1,297 of the 1,455 samples . Of the 158 samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 76 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.

J AOAC Int, 2002 May-Jun, 85(3), 576 - 92
Evaluation of VIDAs Immuno-concentration Salmonella assay Plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) for detection of Salmonella in selected foods: collaborative study; Lepper WA et al.; The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study . Thirty-two laboratories participated in the evaluation . Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey . The 2 methods were in agreement for 1,283 of the 1,440 test samples . Of the 157 test samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 75 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.

Jpn J Infect Dis, 2002 Apr, 55(2), 45 - 6
Antibiotic susceptibility pattern of Salmonella worthington isolated from neonates--a retrospective study; Ghadage DP et al.; Salmonella worthington is an emerging pathogen and has been implicated in a number of outbreaks of neonatal meningitis and septicemia . Over a period of 5 years, a total of 30 strains of this pathogen were isolated from blood and cerebrospinal fluid of neonates suffering from septicemia with or without meningitis . Most of these strains were resistant to the penicillin group of antibiotics, and many were resistant to cefotaxime . Sixty percent of the isolates were resistant to amikacin; 86% were resistant to chloramphenicol, and none were resistant to ciprofloxacin or norfloxacin . Parenteral fluoroquinolone should be included as part of antibiotic therapy in suspected cases of neonatal meningitis due to S . worthington.

J Bacteriol, 2002 Jul, 184(14), 3774 - 84
A Salmonella enterica serovar typhimurium hemA mutant is highly susceptible to oxidative DNA damage; Elgrably-Weiss M et al.; The first committed step in the biosynthesis of heme, an important cofactor of two catalases and a number of cytochromes, is catalyzed by the hemA gene product . Salmonella enterica serovar Typhimurium hemA26::Tn10d (hemA26) was identified in a genetic screen of insertion mutants that were sensitive to hydrogen peroxide . Here we show that the hemA26 mutant respires at half the rate of wild-type cells and is highly susceptible to the effects of oxygen species . Exposure of the hemA26 strain to hydrogen peroxide results in extensive DNA damage and cell death . The chelation of intracellular free iron fully abrogates the sensitivity of this mutant, indicating that the DNA damage results from the iron-catalyzed formation of hydroxyl radicals . The inactivation of heme synthesis does not change the amount of intracellular iron, but by diminishing the rate of respiration, it apparently increases the amount of reducing equivalents available to drive the Fenton reaction . We also report that hydrogen peroxide has opposite effects on the expression of hemA and hemH, the first and last genes of heme biosynthesis pathway, respectively . hemA mRNA levels decrease, while the transcription of hemH is induced by hydrogen peroxide, in an oxyR-dependent manner . The oxyR-dependent induction is suppressed under conditions that accelerate the Fenton reaction by a mechanism that is not yet understood.

Genet Sel Evol, 2002 Mar-Apr, 34(2), 211 - 9
Heritability of susceptibility to Salmonella enteritidis infection in fowls and test of the role of the chromosome carrying the NRAMP1 gene; Girard-Santosuosso O et al.; 373 thirteen-week-old chicks issued from a commercial cross and 312 chickens from the L2 line were intravenously inoculated with 10 (6) Salmonella enteritidis and the numbers of Salmonella in the spleen, liver and genital organs were assessed 3 days later . Heritabilities of the number of Salmonella were estimated at 0.02 +/-0.04 and 0.05 +/-0.05 in the liver; at 0.29 +/-0.07 and 0.10 +/-0.06 in the spleen; and at 0.16 +/- 0.05 and 0.11 +/-0.08 in the genital organs, in the first and second experiments, respectively . The difference between the two experiments could result from sampling variations and from differences in the genetic structure of the two populations possibly including both heterosis and additive effects as well as their interaction in the first experiment . Genetic correlations between the number of bacteria in the genital organs and liver (0.56 +/-0.58 and 0.76 +/- 0.32 in the first and second experiments, respectively) and spleen (0.37 +/-0.24 and 0.79 +/-0.23) were positive . Moreover a significant within-sire effect of VIL1, a marker gene for NRAMP1, was observed in 117 progeny resulting from 25 informative matings . These results indicate that there are genetic differences in the resistance to visceral infection by S . enteritidis in these commercial egg-laying flocks, and suggest that these differences are at least partly due to genetic polymorphism in the NRAMP1 region.

Ann Trop Med Parasitol, 2002 Mar, 96(2), 203 - 8
Are intestinal helminths a risk factor for non-typhoidal Salmonella bacteraemia in adults in Africa who are seropositive for HIV? A case-control study; Dowling JJ et al.; In Africa, invasive, non-typhoidal Salmonella (NTS) infections are a common but life-threatening complication in adults who are seropositive for HIV . The high prevalence of human infection with intestinal helminths which penetrate the gut could explain the greater importance of NTS bacteraemia in Africa compared with that in industrialized countries . If helminth infection is a major risk factor for NTS it would provide a locally relevant, public-health target . Intestinal helminth carriage in 57 HIV-positive patients with NTS bacteraemia (the cases) was compared with that in 162 HIV-positive controls who were similar to the cases in terms of age, sex, urban dwelling and socio-economic factors . The prevalence of helminth infection, 29% overall, was lower among the cases (18%) than among the controls (33%), giving a crude odds ratio of 0.40 {with a 95% confidence interval (CI) of 0.21-0.9} and an adjusted odds ratio (aOR) of 0.79 (CI = 0.4-1.8) . Five (9%) of the cases and 12 (7%) of the controls were infected with nematodes which penetrate the gut (Ascaris lumbricoides and/or Strongyloides stercoralis) . The aOR for infection with these penetrating worms, corrected for age, sex, urban dwelling and phase of study, was 1.40 (CI = 0.4-4.5) . The present results do not exclude the possibility that helminths play a role in invasive NTS infections, but are not consistent with helminths being a sufficient risk factor in this population to be a public-health target . Anthelmintics are unlikely to have a major impact on preventing NTS bacteraemia in patients diagnosed HIV-positive in Africa.

J Biol Chem, 2002 Sep 6, 277(36), 33127 - 31 Epub 2002 Jun 21.
The ATP:Co(I)rrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica requires the 2'-OH group of ATP for function and yields inorganic triphosphate as its reaction byproduct; Fonseca MV et al.; The specificity of the ATP:corrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica serovar Typhimurium LT2 for its nucleotide substrate was tested using ATP analogs and alternative nucleotide donors . The enzyme showed broad specificity for the nucleotide base and required the 2'-OH group of the ribosyl moiety of ATP for activity . (31)P NMR spectroscopy was used to identify inorganic triphosphate (PPP(i)) as the byproduct of the reaction catalyzed by the CobA enzyme . Cleavage of triphosphate into pyrophosphate and orthophosphate did not occur, indicating that triphosphate cleavage was not required for release of the adenosylcorrinoid product . Triphosphate was a strong inhibitor of the reaction, with 85% of CobA activity lost when the ATP/PPP(i) ratio present in the reaction mixture was 1:2.5.

Vet Microbiol, 2002 Jun 5, 87(1), 73 - 80
Pulsed field gel electrophoresis for animal Salmonella enterica serovar Typhimurium isolates in Taiwan; Tsen HY et al.; Salmonella enterica subspecies enterica serovar Typhimurium is a common pathogen for humans and animals . In order to trace the clonal relationship and to find the circulating strains between human and animal isolates, chromosomal DNAs from 87 serovar Typhimurium strains isolated from animals (pigs were the majority) were subjected to XbaI and SpeI digestion and pulsed field gel electrophoresis (PFGE) . For the 87 animal isolates, 38 PFGE pattern combinations were obtained . As the subtyping results from animal isolates were compared with those from the 45 human isolates, it was found that 14 of the animal isolates and 13 of the human isolates shared a common PFGE pattern combination, i.e., pattern XgSf (or called X5S4) . When these human and animal isolates were subjected to antibiotic susceptibility test using 11 antibiotics, it was found that strains of pattern XgSf (X5S4) belong to a common antibiogram pattern which is tetracycline, gentamicin, ampicillin, streptomycin and chloramphenicol resistant . Since most of the animal and human strains in pattern XgSf were originally isolated from various areas over different years, strains of this PFGE pattern may be the most epidemic strains which circulating between human and animal sources.

Vet Microbiol, 2002 Jun 5, 87(1), 25 - 35
Detection and identification of salmonellas from poultry-related samples by PCR; Oliveira SD et al.; A polymerase chain reaction (PCR) assay was developed for the generic detection of Salmonella sp . and the identification of S . Enteritidis (SE), S . Gallinarum (SG), S . Pullorum (SP) and S . Typhimurium (ST) in material collected in the field from poultry . The specificity and sensitivity of the assay combined with Rappaport-Vassiliadis selective enrichment broth (PCR-RV) were determined, and field samples were analyzed to verify the validity of the method application . Specificity of the assay was tested using 29 SE, 11 SG, 10 ST and 10 SP strains, along with 75 strains of 28 other Salmonella serovars and 21 strains of other bacterial genera . The assay was 100% specific for Salmonella detection and ST identification . The primer pair for SE, SG and SP also detected S . Berta . PCR detection limits for Salmonella at the genus level were 2 ST, 8 SE, 1.1x10(3) SG and 1.8x10(5) SP cells . At the serovar level, detection limits were 7 ST, 1.2x10(3) SE, 4.4x10(7) SG and 1.8x10(6) SP cells . At the genus level, PCR-RV detected approximately 128% more positive field samples than the standard microbiological techniques and results were ready in 48h instead of 7 days . PCR-RV method is diagnostic of Salmonella at the genus level and ST at the serovar level, although other tests are needed to identify SE, SG and SP to serovar level.

Proc Natl Acad Sci U S A, 2002 Jun 25, 99(13), 8608 - 13 Epub 2002 Jun 19.
Overexpression, purification, and site-directed spin labeling of the Nramp metal transporter from Mycobacterium leprae; Reeve I et al.; It has long been recognized that the pathogenicity of a broad range of intracellular parasites depends on the availability of transition metal ions, especially iron . Nramp1 (natural resistance-associated macrophage protein 1), a proton-coupled divalent metal ion transporter, has been identified as a controlling factor in the resistance or susceptibility to infection with a diverse range of intracellular pathogens such as Toxoplasma, Salmonella, Mycobacterium, and Leishmania . The role of divalent metal ion transport is even more compelling given the existence of Nramp homologs in several intracellular parasites, such as mycobacteria . We have confirmed the functional homology of the Nramp homologue from Mycobacterium leprae by using a yeast complementation assay for divalent cation uptake . To facilitate a concerted biochemical and structural analysis of this important class of transporters, the M . leprae Nramp was expressed in Escherichia coli . Dual affinity tags were engineered at the N and C termini to allow for isolation of full-length protein at >95% purity . Site-directed spin labeling of Cys-299 reveals a flexible hinge-like domain . A weak dipolar interaction is detected between the nitroxide and paramagnetic transition ions, indicating this position is approximately 19 A from the nearest high affinity binding site.

FEMS Microbiol Lett, 2002 Jun 18, 212(1), 87 - 93
Passage in mice causes a change in the ability of Salmonella enterica serovar Oranienburg to survive NaCl osmotic stress: resuscitation from the viable but non-culturable state; Asakura H et al.; An outbreak caused by dried processed squids contaminated with Salmonella Oranienburg occurred in Japan in 1999 . Isolates obtained from the causative food were resistant to NaCl osmotic stress, but isolates from the patients were sensitive to NaCl . Although strains from both sources were almost identical in their virulence in mice, a NaCl-resistant strain from food (Sa9911T) became NaCl-sensitive after passage in mice and a NaCl-sensitive strain from one patient (Sa99004) retained NaCl sensitivity after such passage . When dried squid was contaminated experimentally with both strains during processing, only Sa9911T was recovered directly from the final product . Nevertheless, the viability of the Sa99004 cells was over 90% found by fluorescent staining . We suggested that Sa99004 might become viable but non-culturable (VNC) by NaCl stress . This hypothesis was confirmed by resuscitation by efficient enrichment . We concluded that VNC S . Oranienburg would be potentially dangerous contaminants of NaCl-preserved foods and that measures to ensure their detection should be taken at the time of food inspection.

Res Vet Sci, 2002 Jun, 72(3), 169 - 75
Molecular tools for epidemiological investigations of S . enterica subspecies enterica infections; Liebana E; Salmonella infection is one of the most prevalent reported food-borne diseases in industrialised countries, most often associated with eating contaminated eggs, poultry and pork . Traditionally, epidemiological investigations for Salmonella enterica have been based on phenotypic characteristics . However, the predominance of certain phenotypes within hosts or locations makes further epidemiological subgrouping necessary . The combination of conventional and molecular epidemiology data is yielding important insights into the understanding of the epidemiology of many infectious diseases, although at present there is no consensus on which molecular method is best suited for intraserotype differentiation within S . enterica . This paper reviews the current methodology for some of the most prevalent animal and human-associated serotypes . Crown

Int J Colorectal Dis, 2002 Jul, 17(4), 275 - 9 Epub 2001 Dec 06.
Toxic megacolon due to Salmonella: a case report and review of the literature; Chaudhuri A et al.; BACKGROUND AND AIMS: Salmonella colitis is an unusual cause of toxic megacolon . We provide an overview of this condition and report a single case . PATIENTS AND METHODS: A 62-year-old man underwent subtotal colectomy with ileostomy formation for toxic megacolon due to Salmonella enteritidis phage type 4 colitis, followed by reversal with an ileorectal anastomosis . RESULTS: Twenty-seven cases have been described in the literature . These were first treated conservatively, with antibiotics and systemic/local steroids, and some proceded to surgery . CONCLUSION: Salmonella is a rare cause of toxic megacolon, but it can behave opportunistically in patients with ulcerative colitis . S . enteritidis phage type 4 is typically transmitted via raw or uncooked eggs in most cases of salmonellosis attributed to this organism . The disease is rapidly progressive, and death may ensue due to septicaemia and/or perforation . Toxic megacolon is treated aggressively, initially medically, with high-dose steroids and attention to fluid balance, ulcerative colitis being the usual working diagnosis . Once Salmonella is cultured, appropriate antibiotics are commenced . Non-surgical decompression may be appropriate in some cases, but early surgical intervention is required for failed response to these measures or rapid deterioration in the patient's condition . Following initial surgery - often subtotal colectomy and ileostomy formation - continuity may be restored . For most patients with ulcerative colitis ileal pouch anal anastomosis is the operation of choice, but ileorectal anastomosis may be safely performed for Salmonella-induced toxic megacolon . Prevention is better than cure, and therefore health education needs to reinforce avoidance of use of raw or uncooked eggs.

Proc Natl Acad Sci U S A, 2002 Jun 25, 99(13), 8784 - 9 Epub 2002 Jun 18.
Polynucleotide phosphorylase is a global regulator of virulence and persistency in Salmonella enterica; Clements MO et al.; For many pathogens, the ability to regulate their replication in host cells is a key element in establishing persistency . Here, we identified a single point mutation in the gene for polynucleotide phosphorylase (PNPase) as a factor affecting bacterial invasion and intracellular replication, and which determines the alternation between acute or persistent infection in a mouse model for Salmonella enterica infection . In parallel, with microarray analysis, PNPase was found to affect the mRNA levels of a subset of virulence genes, in particular those contained in Salmonella pathogenicity islands 1 and 2 . The results demonstrate a connection between PNPase and Salmonella virulence and show that alterations in PNPase activity could represent a strategy for the establishment of persistency.

Proc Natl Acad Sci U S A, 2002 Jun 25, 99(13), 8956 - 61 Epub 2002 Jun 18.
Evolutionary genomics of Salmonella: gene acquisitions revealed by microarray analysis; Porwollik S et al.; The presence of homologues of Salmonella enterica sv . Typhimurium LT2 genes was assessed in 22 other Salmonella including members of all seven subspecies and Salmonella bongori . Genomes were hybridized to a microarray of over 97% of the 4,596 annotated ORFs in the LT2 genome . A phylogenetic tree based on homologue content, relative to LT2, was largely concordant with previous studies using sequence information from several loci . Based on the topology of this tree, homologues of genes in LT2 acquired by various clades were predicted including 513 homologues acquired by the ancestor of all Salmonella, 111 acquired by S . enterica, 105 by diphasic Salmonella, and 216 by subspecies 1, most of which are of unknown function . Because this subspecies is responsible for almost all Salmonella infections of mammals and birds, these genes will be of particular interest for further mechanistic studies . Overall, a high level of gene gain, loss, or rapid divergence was predicted along all lineages . For example, at least 425 close homologues of LT2 genes may have been laterally transferred into Salmonella and then between Salmonella lineages.

Vet Immunol Immunopathol, 2002 Sep 10, 87(3-4), 423 - 8
Candidate genes for resistance to Salmonella enteritidis colonization in chickens as detected in a novel genetic cross; Lamont SJ et al.; Salmonellosis is a zoonotic disease that is problematic for both animal production and food safety . A novel genetic cross, named the Iowa Salmonella response resource population (ISRRP), was established to elucidate the genetic control of resistance to Salmonella enteritidis (SE) colonization in young chicks, to characterize unique resistance alleles, and to estimate gene interaction effects . Outbred broiler sires were mated with dams of diverse, highly inbred, light-bodied lines to produce an F(1) generation that was informative for all heterozygous alleles of the sires . Mating F(1) sires back to dams of the corresponding inbred line produced a backcross generation . To mimic the natural route of exposure and thus afford the opportunity to investigate mucosal immunity, pathogenic SE were inoculated into the esophagus of day-old chicks . After 1 week, the SE colonizing the cecal lumen and the spleen were enumerated . Candidate genes were selected for analysis based upon one of the two criteria . Functional candidates were genes with reported activity related to the tested traits . Positional candidates were genes mapped near microsatellites that were linked, in other phases of this project, with antibody levels to SE vaccine . Broiler sire alleles of the MHC class I, NRAMP1, PSAP, and IAP1 genes showed association with SE colonization in the F(1) generation of this novel disease resistance resource population.

Appetite, 2002 Jun, 38(3), 189 - 97
Public perception of a range of potential food risks in the United Kingdom; Kirk SF et al.; This study aimed to use a standard questionnaire to obtain a nationally representative sample of opinions on a range of potential food risks . Participants were a national sample of 1182 subjects selected using three different approaches: random and sentinel postal samples and a telephone survey . A modified psychometric questionnaire (the Perceived Food Risk Index) was administered to subjects on three occasions, spanning five time-points . Baseline data collection was undertaken from October to December 1998 (phase 1) . The second wave of data collection was undertaken over three time-points in February, April and July 1999 (one-third of respondents to phase 1 at each time-point - data combined as phase 2), and the final phase of data collection was between October and December 1999 (phase 3) . Principal components analysis was used to assess the intercorrelations between the items on the questionnaire . Two main components were identified as 'dread' and 'knowledge' . Saturated fats were perceived as the least dreaded and the most known of the potential risks considered, while bovine spongiform encephalopathy and Salmonella were the risks dreaded the most . There was a slight perception that the potential risks had become more known over the year, especially for growth hormones . This study has raised a number of important issues for risk communicators . Despite current policy aimed at reducing fat intake, this will be difficult to achieve at a population level since people are not worried about its impact, yet food safety continues to be a significant concern to the public .

Environ Manage, 2002 Apr, 29(4), 510 - 5
The effect of environmental conditions on the ability of a constructed wetland to disinfect municipal wastewaters; Zdragas A et al.; Constructed wetlands are widely used all over the world for the treatment of municipal wastewaters, which are characterized by high concentrations of pathogens . The objectives of this study were (1) to study the effect of solar radiation and temperature on the ability of a constructed wetland to reduce the concentration of total coliforms (TC), and (2) to evaluate the relationship between the presence of Salmonella spp . in the outflow and the concentration of TC . The results of this study showed that under Mediterranean environmental conditions, the percentage reduction in coliforms was lower during winter compared to all other seasons . Maximum removal of coliforms was achieved under conditions of high solar radiation and temperature . In addition, solar radiation was found to play a greater role in coliform die-off at low temperatures than at high temperatures . Finally, it was found that the probability of Salmonella spp . appearance in the outflow of the wetland was related to the concentration of TC . The increase in coliform bacteria in the effluents also increased the chances of Salmonella appearance . The risk of Salmonella spp . appearance in the outflow is minimized when the concentration of TC is below 10(2)/100 mL.

J Pak Med Assoc, 2002 Mar, 52(3), 123 - 7
Therapeutic re-appraisal of multiple drug resistant Salmonella typhi (MDRST) in Pakistani children; Hazir T et al.; BACKGROUND: The emergence of multi drug-resistant Salmonella typhi (MDRST) in many developing countries including Pakistan, has led to a search for suitable alternatives to conventional therapy . Quinolones have been found to be an effective alternative for the treatment of MDRST, in adults as well as in children . METHODS: The efficacy of various therapeutic regimens currently used for the treatment of Typhoid was analysed . Children 1 month to 12 years of age admitted to the Children's Hospital from 1990 to 1993 with fever and Salmonella typhi isolated from blood cultures were included in this retrospective analysis . RESULTS: The cumulative prevalence of Multiple Drug Resistant Salmonella typhi (MDRST) was 67.2% . Only 32.8% of isolated Salmonella typhi were susceptible to chloramphenicol and amoxicillin . The cumulative cure rate with conventional therapy (chloramphenicol or amoxicillin) was 47.4% and 53.6% children needed a change of therapy . The average hospital stay for the non-responders to conventional therapy was 9.2 days as compared to 7.7 days for the responders . The average hospital stay of the patients treated with a third generation cephalosporin was 12.7 days . Patients treated with ofloxacin, a flouroquinolone drug, did not need a change of therapy . The average hospital stay of the patients treated with flouroquinolones was 6.2 days . CONCLUSION: There was a high prevalence of multiple drug resistant typhoid fever in hospitalized children, leading to a high failure rate with conventional therapy . This resulted in frequent change of therapy, delayed defervesence and prolonged hospital stay . The flouroquinolones were found to be the most effective drug against MDRST.

Ann Trop Paediatr, 2002 Jun, 22(2), 183 - 6
Typhoidal focal suppurative lymphatic abscess; Singh NP et al.; We describe a submandibular suppurative lymphatic abscess caused by Salmonella typhi in an 8-year-old child . The diagnosis was confirmed by repeated isolation of S . typhi from the abscess . A literature search found no previous report of a similar nature and this therefore seems to be the first case report of focal suppurative typhoidal lymphatic abscess . The child responded to cephalexin and surgical drainage.

Ann Trop Paediatr, 2002 Jun, 22(2), 165 - 71
Retrospective comparison of management of gastro-enteritis in hospitalised children; Nelson EA et al.; In Hong Kong, bacterial pathogens, the majority of them Salmonellae, cause approximately one-third of paediatric admissions for diarrhoea . This study retrospectively reviewed inpatient gastro-enteritis management, with particular focus on antibiotic use . Antibiotics are generally recommended for Salmonella gastro-enteritis in infants under 3 months of age but not for older infants and children unless they are so toxic that bacteraemia is suspected . Three groups of children admitted with acute gastro-enteritis were randomly identified from a computerised discharge database . Based on pathological reports held in the case records department, the final groups for analysis were Salmonella (n = 86), rotavirus (n = 55) and non-specified (n = 126) . Epi Info version 6 (CDC, Atlanta) was used for data entry and analysis . Compared with a combined rotavirus/non-specified group, the Salmonella group were significantly more likely to have blood (OR 6.1, 95% CI 3.2-11.7, p < 0.0001) and mucus (OR 4.8, 95% CI 2.6-8.9, p < 0.0001) in the stool, fever during admission (OR 3.6, 95% CI 1.6-8.4, p = 0.001), more stools per day (median 6.2 vs 4.2, p < 0.0001), a longer stay in hospital (median 3.4 vs 2 days, p < 0.0001) and to be younger (median 7.1 vs 14.6 mths, p < 0.0001) . The Salmonella group were more likely to have been given antibiotics (38% vs 15%, OR 3.6, 95% CI 1.9-6.9, p < 0.0001) but age did not influence the likelihood that antibiotics would be given.

Ann Ig, 2002 Mar-Apr, 14(2), 97 - 103
{Survey of the presence of bacterial pathogens in foods sold at retail stores in the city of Cassino}; Langiano E et al.; The presence of bacterial food pathogens was evaluated in 154 food samples collected from supermarkets and butchers in the city of Cassino (South-Central Italy) . Food pathogens were identified in 17.5% of the total food samples . In the raw meat samples, 24.6% tested positives for Listeria monocytogenes, 4.3% for Salmonella and 2.9% for Escherichia coli O157 . Y . enterocolitica, only investigated in pork meat, was identified in 7.4% of the samples . In poultry, L . monocytogenes was identified in 55% of the samples.

Arch Orthop Trauma Surg, 2002 Jun, 122(5), 306 - 7 Epub 2002 Mar 02.
Ruptured abdominal aortic aneurysm associated with a psoas abscess; Inufusa A et al.; A case of abdominal aortic aneurysm infected by Salmonella dublin is presented . Computed tomography (CT) revealed an abdominal aortic rupture associated with a psoas abscess . An axillo-femoral bypass was performed . The aneurysm and the psoas abscess were resected.

Antimicrob Agents Chemother, 2002 Jul, 46(7), 2257 - 61
Novel class 1 integron (InS21) carrying blaCTX-M-2 in Salmonella enterica serovar infantis; Di Conza J et al.; The genetic organization of the region coding for CTX-M-2 in Salmonella enterica serovar Infantis was determined by PCR mapping . This gene seems to have been mobilized from the Kluyvera ascorbata chromosome to a complex sulI-type integron, similar to In6 and In7.

Prev Vet Med, 2002 Jun 25, 54(2), 157 - 68
Risk factors for clinical Salmonella enterica subsp . enterica serovar Typhimurium infection on Dutch dairy farms; Veling J et al.; Risk factors for outbreaks in 1999 of clinical Salmonella enterica subsp . enterica serovar Typhimurium infection on dairy farms were studied in a matched case-control study with 47 case farms and 47 control farms . All 47 case farms experienced a clinical outbreak of salmonellosis which was confirmed with a positive bacteriologic culture for serovar Typhimurium in one or more samples . Serovar Typhimurium phage type 401 and 506 (definitive type 104, DT104) were the most frequently isolated phage types (13 isolates) . On most farms (66%), clinical signs were seen only among adult cows . The most frequently reported clinical signs were diarrhoea (in 92% of the farms) and depression (in 79% of the farms).Control farms were matched on region and had no history of salmonellosis . A questionnaire was used to collect data on case and control farms . The relationship between serovar Typhimurium status of the farm and possible risk factors was tested using conditional logistic regression . Significant factors in the final model were presence of cats on the farm (OR=0.06), purchase of manure (OR=21.5), feeding colostrum only from own dam (OR=0.08), a non-seasonal calving pattern (OR=25), unrestricted grazing of lactating cows (OR=0.07), and a high mean mowing percentage of pasture (OR=1.02).

Vet Microbiol, 2002 Jul 22, 87(4), 315 - 25
Pathogenesis of infections with Salmonella enterica subsp . enterica serovar Muenchen in the turtle Trachemys scripta scripta; Pasmans F et al.; The pathogenesis of Salmonella enterica subsp . enterica serovar Muenchen infections in the aquatic turtle Trachemys scripta scripta was studied . After oral infection with 5x10(5)cfu of serovar Muenchen of 10-14-month-old turtles, kept at 26 degrees C, the intestine and especially the ileum, caecum and colon was colonized . Invasion of the intestinal wall, causing histopathological lesions, and colonization of internal organs were not observed . Serovar Muenchen was only isolated from turtles for 8 days after exposure . Keeping the turtles at 37 degrees C caused colonization of liver and spleen in two of six orally infected turtles and augmented the numbers of bacteria in the intestinal tract . In contrast to oral infections, intraperitoneal infections of turtles with serovar Muenchen enabled the bacterium to persist inside the host for at least 5 weeks . Clearance of serovar Muenchen from the liver and blood was more pronounced at 26 degrees C than at 37 degrees C . ELISA antibodies were demonstrated in intraperitoneally but not in orally infected turtles kept at 26 degrees C . In conclusion, the lack of persistence and invasiveness of serovar Muenchen in T . s . scripta after oral exposure might be due to the turtle's relatively low body temperature and/or the absence of well-organized gut-associated lymphoid tissue.

J Vet Med B Infect Dis Vet Public Health, 2002 May, 49(4), 163 - 8
Comparison of ITS profiling, REP- and ERIC-PCR of Salmonella Enteritidis isolates from Poland; Chmielewski R et al.; Thirty-one Salmonella Enteritidis strains isolated from chickens, broilers and hens were analysed by genotypic typing including REP-PCR . ERIC-PCR and ITS profiling (PCR-ribotyping) . Analysis of DNA banding patterns generated by REP-PCR revealed the presence of 22 different genotypes, which were grouped by dendrogram analysis into three distinct lineages (maximum similarity approx . 50%) . Each isolate of S . Enteritidis analysed by ERIC-PCR generated an individual DNA pattern . Again, these isolates could be divided into three distinct genomic groups (maximum similarity approx . 60%) by their ERIC-PCR fingerprints . REP- and ERIC-PCR were found to be more discriminatory for typing of S . Enteritidis than ITS profiling . Amplification of the 16S-23S rDNA spacer region gave nine different profiles of DNA, subdivided into two closely related groups by dendrogram analysis . In summary, data obtained by genotyping methods for S . Enteritidis isolates from regions located in the south-west and the central parts of Poland revealed an enormous heterogeneity among analysed samples, and proved that REP- and ERIC-PCR are highly discriminatory techniques, which can be used, in addition to conventional methods, in epidemiological studies of S . Enteritidis infections.

Mol Microbiol, 2002 Jun, 44(5), 1309 - 21
Topology of the Salmonella invasion protein SipB in a model bilayer; McGhie EJ et al.; A critical early event in Salmonella infection is entry into intestinal epithelial cells . The Salmonella invasion protein SipB is required for the delivery of bacterial effector proteins into target eukaryotic cells, which subvert signal transduction pathways and cytoskeletal dynamics . SipB inserts into the host plasma membrane during infection, and the purified protein has membrane affinity and heterotypic membrane fusion activity in vitro . We used complementary biochemical and biophysical techniques to investigate the topology of purified SipB in a model membrane . We show that the 593 residue SipB is predominantly alpha-helical in aqueous solution, and that no significant change in secondary structural content accompanies lipid interaction . SipB contains two -helical transmembrane domains (residues 320-353 and 409-427), which insert deeply into the bilayer . Their integration allowed the hydrophilic region between the hydrophobic domains (354-408) to cross the bilayer . SipB membrane integration required both the hydrophobic domains and an additional helical C-terminal region (428-593) . Further spectroscopic analysis of these domains in isolation showed that the hydrophobic regions insert obliquely into the bilayer, whereas the C-terminal domain associates with the bilayer surface, tilted parallel to the membrane . The combined data suggest a topological model for membrane-inserted SipB.

Mol Microbiol, 2002 Jun, 44(5), 1235 - 50
Autoinduction of the ompR response regulator by acid shock and control of the Salmonella enterica acid tolerance response; Bang IS et al.; Salmonella enterica serovar Typhimurium periodically experiences acid stress in a variety of host and non-host environments . An encounter with non-lethal acid stress (pH > 4) induces an assortment of physiological changes, called the acid tolerance response (ATR), that helps the cell to tolerate extreme low pH (pH 3) . These physiological changes differ in log phase and stationary phase cells and are controlled by different regulatory proteins . OmpR is an acid-induced response regulator critical to the stationary phase ATR but not to the log phase ATR . As OmpR also controls the expression of the acid-induced virulence operon ssrAB, acid shock induction of ompR was examined to gain insight into how Salmonella links virulence with survival at extreme acid pH . The results indicate that acid pH induces ompR from a promoter different from that used for basal expression . Transcription from this promoter is repressed by the histone-like protein H-NS and requires OmpR-P for induction . The classic sensor kinase EnvZ and acetyl phosphate collaborate to produce the optimum level of OmpR-P needed for autoinduction . Although OmpR-P is required for acid-induced expression of ompR in wild-type cells, OmpR is not needed for ompR transcription in the absence of H-NS . Thus, the role of OmpR-P in autoinduction is to help to counteract repression by H-NS . This evidence, combined with the finding that relaxing DNA supercoiling with novobiocin also increased ompR transcription, suggests that acid stress induces ompR by altering local DNA topology, not by changing the phosphorylation status of OmpR.

FEBS Lett, 2002 Jun 19, 521(1-3), 105 - 8
Optimization of GFP levels for analyzing Salmonella gene expression during an infection; Wendland M et al.; Green fluorescent protein (GFP) is an attractive reporter for Salmonella gene expression analysis but might interfere with virulence when expressed at high levels . To identify suitable GFP levels, we constructed a series of Salmonella strains expressing different amounts of GFP and measured their fluorescence and colonization levels in infected mice . The results show that GFP concentrations in the range of 7000-200,000 molecules per Salmonella cell are detectable in ex vivo samples using flow cytometry, and cause no major Salmonella virulence defect . Appropriate GFP levels can be obtained with weak promoters and stable GFP, or strong promoters and destabilized GFP.

Food Chem Toxicol, 2002 Aug, 40(8), 1165 - 70
Pseudouridine, an antimutagenic substance in beer towards N-methyl-N'-nitro-N-nitrosoguanidine (MNNG); Yoshikawa T et al.; Previously we reported that beer is antimutagenic against several food-derived mutagens including heterocyclic amines . We describe here the isolation and identification of pseudouridine from beer as an antimutagenic substance against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) . All of the 17 samples of beer tested showed inhibition of the MNNG mutagenicity in Salmonella . Extensive fractionation through chromatography of the active components from a freeze-dried beer sample gave six antimutagenic fractions . One contained pseudouridine, as characterized by the UV spectra, nuclear magnetic resonance, and co-chromatography in HPLC . Pure pseudouridine inhibited the mutagenicity of MNNG in a dose-dependent manner . The amount of pseudouridine in the beer sample, estimated at about 0.4 mg/100 ml beer, can account for 3% of the total antimutagenicity of beer . Thus, the major active components in beer remain to be identified . The role of pseudouridine in inhibiting the mutagenicity of MNNG is to be studied further . Among analogs of pseudouridine, spongouridine, but not uridine, was antimutagenic against MNNG . The bacterial mutagenicity of another methylating agent N-methyl-N-nitrosourea was also inhibited by pseudouridine . Pseudouridine is the first example among nucleosides to be shown to possess an antimutagenic property.

Food Chem Toxicol, 2002 Aug, 40(8), 1085 - 90
Genotoxic effects of ochratoxin A in human-derived hepatoma (HepG2) cells; Ehrlich V et al.; Ochratoxin A (OTA) is a widespread mycotoxin that occurs in many commodities from grains to coffee beans all over the world . Evidence is accumulating that OTA may cause cancer in humans . The compound was tested in micronucleus (MN) and single-cell gel electrophoresis (SCGE) assays in human-derived hepatoma (HepG2) cells and caused pronounced dose-dependent effects at exposure concentrations of 5 microg/ml and greater . On the contrary, no induction of His(+) revertants was found in Salmonella microsome assays with strains TA98 and TA100 with HepG2-derived enzyme (S9) mix in liquid incubation assays under identical exposure concentrations . Taken together, our results indicate that OTA is clastogenic in the human-derived cells . These findings support the assumption that this mycotoxin may cause genotoxic effects in hepatic tissue of humans.

Mol Microbiol, 2002 Jun, 44(6), 1637 - 50
Structural characterization of lipo-oligosaccharide (LOS) from Yersinia pestis: regulation of LOS structure by the PhoPQ system; Hitchen PG et al.; The two-component regulatory system PhoPQ has been shown to regulate the expression of virulence factors in a number of bacterial species . For one such virulence factor, lipopolysaccharide (LPS), the PhoPQ system has been shown to regulate structural modifications in Salmonella enterica var Typhimurium . In Yersinia pestis, which expresses lipo-oligosaccharide (LOS), a PhoPQ regulatory system has been identified and an isogenic mutant constructed . To investigate potential modifications to LOS from Y . pestis, which to date has not been fully characterized, purified LOS from wild-type plague and the phoP defective mutant were analysed by mass spectrometry . Here we report the structural characterization of LOS from Y . pestis and the direct comparison of LOS from a phoP mutant . Structural modifications to lipid A, the host signalling portion of LOS, were not detected but analysis of the core revealed the expression of two distinct molecular species in wild-type LOS, differing in terminal galactose or heptose . The phoP mutant was restricted to the expression of a single molecular species, containing terminal heptose . The minimum inhibitory concentration of cationic antimicrobial peptides for the two strains was determined and compared with the wild-type: the phoP mutant was highly sensitive to polymyxin . Thus, LOS modification is under the control of the PhoPQ regulatory system and the ability to alter LOS structure may be required for survival of Y . pestis within the mammalian and/or flea host.

Mol Microbiol, 2002 Jun, 44(6), 1589 - 98
Conjugal transfer of the virulence plasmid of Salmonella enterica is regulated by the leucine-responsive regulatory protein and DNA adenine methylation; Camacho EM et al.; Host-encoded functions that regulate the transfer operon (tra) in the virulence plasmid of Salmonella enterica (pSLT) were identified with a genetic screen . Mutations that decreased tra operon expression mapped in the lrp gene, which encodes the leucine-responsive regulatory protein (Lrp) . Reduced tra operon expression in an Lrp- background is caused by lowered transcription of the traJ gene, which encodes a transcriptional activator of the tra operon . Gel retardation assays indicated that Lrp binds a DNA region upstream of the traJ promoter . Deletion of the Lrp binding site resulted in lowered and Lrp-independent traJ transcription . Conjugal transfer of pSLT decreased 50-fold in a Lrp- background . When a FinO- derivative of pSLT was used, conjugal transfer from an Lrp- donor decreased 1000-fold . Mutations that derepressed tra operon expression mapped in dam, the gene encoding Dam methyltransferase . Expression of the tra operon and conjugal transfer remain repressed in an Lrp- Dam- background . These observations support the model that Lrp acts as a conjugation activator by promoting traJ transcription, whereas Dam methylation acts as a conjugation repressor by activating FinP RNA synthesis . This dual control of conjugal transfer may also operate in other F-like plasmids such as F and R100.

Infect Immun, 2002 Jul, 70(7), 3843 - 55
The Salmonella enterica serotype typhimurium effector proteins SipA, SopA, SopB, SopD, and SopE2 act in concert to induce diarrhea in calves; Zhang S et al.; Salmonella enterica serotype Typhimurium requires a functional type III secretion system encoded by Salmonella pathogenicity island 1 (SPI1) to cause diarrhea . We investigated the role of genes encoding secreted target proteins of the SPI1-associated type III secretion system for enteropathogenicity in calves . Salmonella serotype Typhimurium strains having mutations in sptP, avrA, sspH1, or slrP induced fluid secretion in the bovine ligated ileal loop model at levels similar to that of the wild type . In contrast, mutations in sipA, sopA, sopB, sopD, or sopE2 significantly reduced fluid accumulation in bovine ligated ileal loops at 8 h postinfection . A strain carrying mutations in sipA, sopA, sopB, sopD, and sopE2 (sipA sopABDE2 mutant) caused the same level of fluid accumulation in bovine ligated ileal loops as a strain carrying a mutation in sipB, a SPI1 gene required for the translocation of effector proteins into host cells . A positive correlation was observed between the severity of histopathological lesions detected in the ileal mucosa and the levels of fluid accumulation induced by the different mutants . After oral infection of calves, the Salmonella serotype Typhimurium sipAsopABDE2 mutant caused only mild diarrhea and was more strongly attenuated than strains having only single mutations . These data demonstrate that SipA, SopA, SopB, SopD, and SopE2 are major virulence factors responsible for diarrhea during Salmonella serotype Typhimurium infection of calves.

Infect Immun, 2002 Jul, 70(7), 3611 - 20
Expression of the Plasmodium falciparum immunodominant epitope (NANP)(4) on the surface of Salmonella enterica using the autotransporter MisL; Ruiz-Perez F et al.; Gram-negative bacterial proteins which are exported from the cytosol to the external environment by the type V secretion system are also known as autotransporters . Once translocated to the periplasmic compartment by the sec-dependent general secretory pathway, their C-terminal domain forms a pore through which the N-terminal domain travels to the outer membrane without the need of other accessory proteins . MisL (protein of membrane insertion and secretion) is a protein of unknown function located in the pathogenicity island SPI-3 of Salmonella enterica and classified as an autotransporter due to its high homology to Escherichia coli AIDA-I . In the present work, the MisL C-terminal translocator domain was used to display the immunodominant B-cell epitope of the circumsporozoite protein (CSP) from Plasmodium falciparum on the surface of Salmonella enterica serovar Typhimurium (serovar Typhimurium SL3261) and serovar Typhi (serovar Typhi CVD 908) . The MisL beta domain was predicted by alignment with AIDA-I, amplified from serovar Typhimurium SL3261, cloned in a plasmid fused to four repeats of the tetrapeptide NANP behind the Escherichia coli heat-labile enterotoxin B subunit signal peptide to ensure periplasmic traffic, and expressed under the control of the anaerobically inducible nirB promoter . The fusion protein was translocated to the outer membrane of both bacterial strains, although the foreign epitope was displayed more efficiently in serovar Typhimurium SL3261, which elicited a better specific antibody response in BALB/c mice . More importantly, antibodies were able to recognize the native CSP in P . falciparum sporozoites . These results confirm that MisL is indeed an autotransporter and that it can be used to express foreign immunogenic epitopes on the surface of gram-negative bacteria.

Infect Immun, 2002 Jul, 70(7), 3546 - 50
MD-2, a novel accessory molecule, is involved in species-specific actions of Salmonella lipid A; Muroi M et al.; Salmonella lipid A is inactive in human macrophages despite being potently active in murine macrophages . We investigated the molecular basis for this species-specific action of Salmonella lipid A . When murine CD14 (mCD14), mTLR4, and mMD-2 were all expressed in human monocytic THP-1 cells, these cells were capable of responding to Salmonella lipid A . Expressing each of these proteins separately did not impart such responsiveness . Expression of mTLR4 plus mMD-2, but not mCD14 plus mTLR4 or mCD14 plus mMD-2, conferred this responsiveness . In THP-1 cells expressing mCD14, mTLR4, and mMD-2, replacing mCD14 with human CD14 had no effect on responsiveness to Salmonella lipid A or synthetic Salmonella-type lipid A (compound 516) . When mTLR4 was replaced with human TLR4, the responses to these lipid A preparations were decreased to half, and the replacement of mMD-2 decreased responsiveness to one-third, although the responses to Escherichia coli lipid A or synthetic E . coli-type lipid A (compound 506) were not affected . These results indicate that both TLR4 and MD-2 participate in the species-specific action of Salmonella lipid A.

Infect Immun, 2002 Jul, 70(7), 3457 - 67
Characterization of Salmonella enterica derivatives harboring defined aroC and Salmonella pathogenicity island 2 type III secretion system (ssaV) mutations by immunization of healthy volunteers; Hindle Z et al.; The attenuation and immunogenicity of two novel Salmonella vaccine strains, Salmonella enterica serovar Typhi (Ty2 Delta aroC Delta ssaV, designated ZH9) and S . enterica serovar Typhimurium (TML Delta aroC Delta ssaV, designated WT05), were evaluated after their oral administration to volunteers as single escalating doses of 10(7), 10(8), or 10(9) CFU . ZH9 was well tolerated, not detected in blood, nor persistently excreted in stool . Six of nine volunteers elicited anti-serovar Typhi lipopolysaccharide (LPS) immunoglobulin A (IgA) antibody-secreting cell (ASC) responses, with three of three vaccinees receiving 10(8) and two of three receiving 10(9) CFU which elicited high-titer LPS-specific serum IgG . WT05 was also well tolerated with no diarrhea, although the administration of 10(8) and 10(9) CFU resulted in shedding in stools for up to 23 days . Only volunteers immunized with 10(9) CFU of WT05 mounted detectable serovar Typhimurium LPS-specific ASC responses and serum antibody responses were variable . These data indicate that mutations in type III secretion systems may provide a route to the development of live vaccines in humans and highlight significant differences in the potential use of serovars Typhimurium and Typhi.

J Rheumatol, 2002 Jun, 29(6), 1214 - 8
Risk factors of mortality for salmonella infection in systemic lupus erythematosus; Tsao CH et al.; OBJECT: To investigate the risk factors of mortality for Salmonella infection in patients with systemic lupus erythematosus (SLE) . METHODS: Between 1995 and 1999 we reviewed 37 cases of Salmonella infection in 31 patients with SLE from a total of 1191 hospitalized patients with SLE at a medical center in Taiwan . Contrasting cases of patients who died with those who survived, we compared clinical and laboratory characteristics of SLE at the time of Salmonella infection, with special attention to potential risk factors (sex, age, complete blood count and differential count, erythrocyte sedimentation rate, C-reactive protein, complements, Salmonella species, infection site, reinfection, SLE presenting with Salmonella infection, associated non-Salmonella infection, etc.) . RESULTS: The mean age at the onset of SLE in the 8 mortality cases was significantly higher than the 23 cases of survivors (p < 0.05) . Other factors significantly related to death included associated infections other than Salmonella species, reinfection of Salmonella species, and cases of SLE presenting with Salmonella infection . Reinfection and SLE presenting with Salmonella infection were the most important risk factors of mortality for SLE with Salmonella infections: relative risk (CI) 84 (4.3-1638.8) and 63 (3.1-1296.5), respectively . CONCLUSION: Patients with SLE who are older or have associated infections other than Salmonella have an increased mortality rate when they have concurrent Salmonella infection . Patients with Salmonella infection occurring concurrently with the first presentation of SLE and patients with SLE reinfected with Salmonella species are at higher risk of mortality.

Vet Clin North Am Food Anim Pract, 2002 Mar, 18(1), 7 - 34
Biosecurity for neonatal gastrointestinal diseases; Barrington GM et al.; Infectious diarrhea is an important cause of neonatal calf morbidity and mortality that results in significant economic losses in the beef and dairy industries . Although numerous risk factors related to the occurrence of neonatal diarrhea have been identified, they can all be categorized into those that are related to the calf, the pathogens involved, or the environment of the calf . The immune status of calves, specifically the level of passively acquired immunity through colostrum, is the major risk factor related to the calf and the occurrence of diarrhea . Although numerous pathogens have been implicated in the occurrence of neonatal diarrhea, only a relatively limited number are commonly involved . Most should be viewed as secondary opportunists rather than primary pathogens, because none are extraordinarily virulent, and with the exception of Salmonella spp., most are present within the gastrointestinal tract of many healthy, mature cattle . Important risk factors related to pathogens involved in neonatal calf diarrhea involve the size of the inoculum and the occurrence of multiple infections . Finally, when considering the environment and housing conditions in which beef and dairy calves may reside, it is clear that tremendous variations exist . Despite these variations, the risk factors associated with the environment of the calf are also those that are the most amenable to the implementation of general environmental control and monitoring strategies as well as specific biosecurity measures.

Eur J Cardiothorac Surg, 2002 May, 21(5), 935 - 7
Bronchogenic cyst infected by Salmonella enteritidis followed gastroenteritis; Kostopoulos G et al.; Congenital bronchogenic cysts of the lung and mediastinum develop from the ventral foregut during embryogenesis . Bronchogenic cysts are seldom seen in the adults and most are thought to be asymptomatic and free of complications unless they become infected or are large enough to cause pressure on contiguous vital structures such as the tracheal carina, the lung or the esophagus . We present the unique case of a 24-year-old man who developed respiratory symptoms after Salmonella enteritidis infected bronchogenic cyst following Salmonella gastroenteritis.

Int J Exp Pathol, 2002 Feb, 83(1), 1 - 20
Heterogeneity in the granulomatous response to mycobacterial infection in patients with defined genetic mutations in the interleukin 12-dependent interferon-gamma production pathway; Lammas DA et al.; Patients with genetic lesions in the Type-1 cytokine/cytokine receptor pathway exhibit a selective susceptibility to severe infections with poorly pathogenic mycobacteria and non-typhi salmonella spp . These experiments of nature demonstrate that IL-12-dependent IFNgamma production is critical for granuloma formation and therefore host immunity against such pathogens . The essential role of granuloma formation for protective immunity to these organisms is emphasized by the differing granuloma forming capabilities and resultant clinical sequelae observed in these patients which seems to reflect their ability to produce or respond to IFNgamma (Fig . 9) . At one pole of this spectrum, represented by the complete IFNgammaR1/2 deficient patients, there is a complete absence of mature granuloma formation, whereas with the less severe mutations (i.e . partial IFNgammaR1/2, complete IL-12p40 and complete IL-12Rbeta1 deficiency), granuloma formation is very heterogenous with wide variations in composition being observed . This suggests that in the latter individuals, who produce partial but suboptimal IFNgamma responses, other influences, including pathogen virulence and host genotype may also affect the type and scale of the cellular response elicited.

Can Vet J, 2002 Jun, 43(6), 441 - 2
Preliminary assessment of the risk of Salmonella infection in dogs fed raw chicken diets; Joffe DJ et al.; This preliminary study assessed the presence of Salmonella spp . in a bones and raw food (BARF) diet and in the stools of dogs consuming it . Salmonella was isolated from 80% of the BARF diet samples (P < 0.001) and from 30% of the stool samples from dogs fed the diet (P = 0.105) . Dogs fed raw chicken may therefore be a source of environmental contamination.

Kyobu Geka, 2002 Jun, 55(6), 502 - 4
{Mycotic descending thoracic aortic aneurysm complicated by pyothorax postoperatively: report of a case}; Nishiuchi S et al.; We experienced with a case of mycotic descending thoracic aortic aneurysm (MTAA) complicated by pyothorax postoperatively . The graft replacement accompanied with wrapping by omental pedicle flap (OPF) was performed in this case . We considered that causative organism for MTAA was Salmonella species, and discussed effectiveness of the application of OPF to MTAA.

Planta Med, 2002 May, 68(5), 452 - 4
Characterization of the bactericidal activity of the natural diterpene kaurenoic acid; Wilkens M et al.; Kaurenoic acid is a diterpene with selective antibacterial activity against Gram-positive bacteria . The compound is bacteriolytic for Bacillus cereus . This activity was only partially affected by the composition and pH of the culture medium . Loss of the ability to retain the Gram stain and morphological alterations were produced in B . cereus cells exposed to kaurenoic acid . On the other hand, LPS mutants of Salmonella typhi were resistant to the compound, but spheroplasts of Escherichia coli became more sensitive to kaurenoic acid.

Genes Immun, 2002 Jun, 3(4), 196 - 204
Identification of genetic loci controlling bacterial clearance in experimental Salmonella enteritidis infection: an unexpected role of Nramp1 (Slc11a1) in the persistence of infection in mice; Caron J et al.; The Gram-negative bacteria, Salmonella, cause a broad spectrum of clinical diseases in both animals and humans ranging from asymptomatic carriage to life-threatening sepsis . We have developed a model to study the contribution of genetic factors to the susceptibility of 129sv and C57BL/6J inbred mice to Salmonella enteritidis during the late phase of infection . C57BL/6J mice were able to eliminate completely sublethal inoculums of S . enteritidis from their reticuloendothelial system, whereas 129sv mice could not even after 60 days post inoculation . A genome scan performed on 302 (C57BL/6J x 129sv) F2 progeny identified three dominant loci (designated Ses1 to Ses3) that are associated with disease susceptibility in 129sv mice . Two highly significant linkages were identified on chromosomes 1 (Ses1) and 7 (Ses2) with respective LOD scores of 9.9 (P = 1.4 x 10(-11)) at D1Mcg5 and 4.0 (P = 1.9 x 10(-5)) at D7Mit62 . One highly suggestive QTL was located on chromosomes15 (Ses3) with a LOD score 3.4 (P = 1.2 x 10(-4)) . The estimated effects of Ses1, Ses2 and Ses3 on the bacterial clearance were greater in females . Using a model of three loci, with interaction between Ses1 and Ses2 and sex as a covariate, the three QTLs explained 32% of the phenotypic variance . The candidacy of Nramp1 as the gene for Ses1 was evaluated using mice carrying a null allele at Nramp1 (129sv-Nramp1(tm1Mcg)) . These mice have a significantly lower spleen bacterial load compared to the wild-type 129sv mice, strongly suggesting the involvement of Nramp1 in controlling S . enteritidis clearance during the late phase of infection.

Neurology, 2002 Jun 11, 58(11), 1641 - 5
Clinical and pathologic characteristics of nontyphoidal salmonella encephalopathy; Arii J et al.; OBJECTIVE: To investigate the clinical and pathologic characteristics of primary encephalopathy caused by nontyphoidal salmonellosis (NTS) . METHODS: Case records of six Japanese hospitals from 1994 to 1999 were reviewed . Eight cases of primary NTS encephalopathy were identified based on strictly defined criteria: 1) encephalopathic feature defined as altered state of consciousness, altered cognition or personality, or seizures; 2) detection of nontyphoidal Salmonella species in stool; 3) absence of other viral or bacterial infection associated with CNS abnormalities; and 4) absence of alternative explanation by underlying neurologic or systemic disease . Three patients died, three had severe sequelae, and two recovered completely . The authors analyzed their clinical course, neurologic symptoms, and histopathologic findings . RESULTS: NTS encephalopathy was clinically characterized by diffuse and rapidly progressive brain dysfunction and circulatory failure that developed following enteritis . There was no evidence of severe dehydration or sepsis, and encephalopathy was rarely accompanied by abnormal laboratory data, except elevated CSF opening pressure, brain edema on CT, and slow waves on EEG . Pathologic findings included minimal ischemic damage and mild edema in the brain, microvesicular fatty change of the liver, severe enterocolitis but no evidence of dehydration, and no fatal organ damage including microvasculature and endothelial cells . CONCLUSION: Noninfectious encephalopathy associated with nontyphoidal salmonella infection is a distinctive clinical entity that can be differentiated from Reye's syndrome and Ekiri.

J Bacteriol, 2002 Jul, 184(13), 3640 - 8
Activation of prophage eib genes for immunoglobulin-binding proteins by genes from the IbrAB genetic island of Escherichia coli ECOR-9; Sandt CH et al.; Four distinct Escherichia coli immunoglobulin-binding (eib) genes, each of which encodes a surface-exposed protein that binds immunoglobulins in a nonimmune manner, are carried by separate prophages in E . coli reference (ECOR) strain ECOR-9 . Each eib gene was transferred to test E . coli strains, both in the form of multicopy recombinant plasmids and as lysogenized prophage . The derived lysogens express little or no Eib protein, in sharp contrast to the parental lysogen, suggesting that ECOR-9 has an expression-enhancing activity that the derived lysogens lack . Supporting this hypothesis, we cloned from ECOR-9 overlapping genes, ibrA and ibrB (designation is derived from "immunoglobulin-binding regulator"), which together activated eib expression in the derived lysogens . The proteins encoded by ibrA and ibrB are very similar to uncharacterized proteins encoded by genes of Salmonella enterica serovar Typhi and E . coli O157:H7 (in a prophage-like element of the Sakai strain and in two O islands of strain EDL933) . The genomic segment containing ibrA and ibrB has been designated the IbrAB island . It contains regions of homology to the Shiga toxin-converting prophage, Stx2, as well as genes homologous to phage antirepressor genes . The left boundary between the IbrAB island and the chromosomal framework is located near min 35.8 of the E . coli K-12 genome . Homology to IbrAB was found in certain other ECOR strains, including the other five eib-positive strains and most strains of the phylogenetic group B2 . Sequencing of a 1.1-kb portion of ibrAB revealed that the other eib-positive strains diverge by </=0.1% from ECOR-9, whereas eib-negative ECOR-47 diverges by 16%.

J Bacteriol, 2002 Jul, 184(13), 3450 - 6
pfs-dependent regulation of autoinducer 2 production in Salmonella enterica serovar Typhimurium; Beeston AL et al.; Bacterial intercellular communication provides a mechanism for signal-dependent regulation of gene expression to promote coordinated population behavior . Salmonella enterica serovar Typhimurium produces a non-homoserine lactone autoinducer in exponential phase as detected by a Vibrio harveyi reporter assay for autoinducer 2 (AI-2) (M . G . Surette and B . L . Bassler, Proc . Natl . Acad . Sci . USA 95:7046-7050, 1998) . The luxS gene product mediates the production of AI-2 (M . G . Surette, M . B . Miller, and B . L . Bassler, Proc . Natl . Acad . Sci . USA 96:1639-1644, 1999) . Environmental cues such as rapid growth, the presence of preferred carbon sources, low pH, and/or high osmolarity were found to influence the production of AI-2 (M . G . Surette and B . L . Bassler, Mol . Microbiol . 31:585-595, 1999) . In addition to LuxS, the pfs gene product (Pfs) is required for AI-2 production, as well as S-adenosylhomocysteine (SAH) (S . Schauder, K . Shokat, M . G . Surette, and B . L . Bassler, Mol . Microbiol . 41:463-476, 2001) . In bacterial cells, Pfs exhibits both 5'-methylthioadenosine (MTA) and SAH nucleosidase functions . Pfs is involved in methionine metabolism, regulating intracellular MTA and SAH levels (elevated levels of MTA and SAH are potent inhibitors of polyamine synthetases and S-adenosylmethionine dependent methyltransferase reactions, respectively) . To further investigate regulation of AI-2 production in Salmonella, we constructed pfs and luxS promoter fusions to a luxCDABE reporter in a low-copy-number vector, allowing an examination of transcription of the genes in the pathway for signal synthesis . Here we report that luxS expression is constitutive but that the transcription of pfs is tightly correlated to AI-2 production in Salmonella serovar Typhimurium 14028 . Neither luxS nor pfs expression appears to be regulated by AI-2 . These results suggest that AI-2 production is regulated at the level of LuxS substrate availability and not at the level of luxS expression . Our results indicate that AI-2-dependent signaling is a reflection of metabolic state of the cell and not cell density.

J Bacteriol, 2002 Jul, 184(13), 3433 - 41
Spa32 regulates a switch in substrate specificity of the type III secreton of Shigella flexneri from needle components to Ipa proteins; Magdalena J et al.; Type III secretion systems (TTSS) are essential virulence determinants of many gram-negative bacteria and serve, upon physical contact with target cells, to translocate bacterial proteins directly across eukaryotic cell membranes . The Shigella TTSS is encoded by the mxi/spa loci located on its virulence plasmid . By electron microscopy secretons are visualized as tripartite with an external needle, a transmembrane domain, and a cytoplasmic bulb . In the present study, we generated a Shigella spa32 mutant and studied its phenotype . The spa32 gene shows low sequence homology to Salmonella TTSS1 invJ/spaN and to flagellar fliK . The spa32 mutant, like the wild-type strain, secreted the Ipas and IpgD, which are normally secreted via the TTSS, at low levels into the growth medium . However, unlike the wild-type strain, the spa32 mutant could neither be induced to secrete the Ipas and IpgD instantaneously upon addition of Congo red nor penetrate HeLa cells in vitro . Additionally, the Spa32 protein is secreted in large amounts by the TTSS during exponential growth but not upon Congo red induction . Interestingly, electron microscopy analysis of the spa32 mutant revealed that the needle of its secretons were up to 10 times longer than those of the wild type . In addition, in the absence of induction, the spa32 mutant secreted normal levels of MxiI but a large excess of MxiH . Taken together, our data indicate that the spa32 mutant presents a novel phenotype and that the primary defect of the mutant may be its inability to regulate or control secretion of MxiH.

Structure (Camb), 2002 Jun, 10(6), 773 - 86
Variation on a theme of SDR . dTDP-6-deoxy-L- lyxo-4-hexulose reductase (RmlD) shows a new Mg2+-dependent dimerization mode; Blankenfeldt W et al.; dTDP-6-deoxy-L-lyxo-4-hexulose reductase (RmlD) catalyzes the final step in the conversion of dTDP-D-glucose to dTDP-L-rhamnose in an NAD(P)H- and Mg2+-dependent reaction . L-rhamnose biosynthesis is an antibacterial target . The structure of RmlD from Salmonella enterica serovar Typhimurium has been determined, and complexes with NADH, NADPH, and dTDP-L-rhamnose are reported . RmlD differs from other short chain dehydrogenases in that it has a novel dimer interface that contains Mg2+ . Enzyme catalysis involves hydride transfer from the nicotinamide ring of the cofactor to the C4'-carbonyl group of the substrate . The substrate is activated through protonation by a conserved tyrosine . NAD(P)H is bound in a solvent-exposed cleft, allowing facile replacement . We suggest a novel role for the conserved serine/threonine residue of the catalytic triad of SDR enzymes.

Nat Struct Biol, 2002 Jul, 9(7), 518 - 21
The bacterial protein SipA polymerizes G-actin and mimics muscle nebulin; Galkin VE et al.; SipA is a Salmonella protein delivered into host cells to promote efficient bacterial entry, which is essential for pathogenicity . SipA exerts its function by binding F-actin, resulting in the stabilization of F-actin and the stimulation of the bundling activity of fimbrin . Here we show that under low salt conditions where spontaneous nucleation and polymerization of actin do not occur, SipA induces extensive polymerization . We have used electron microscopy and a method for helical image analysis to visualize the complex of actin with the actin-binding fragment of SipA . The SipA fragment binds to actin as a tubular molecule extending approximately 95 A . The main sites of SipA binding on actin involve sequence insertions that are not present in the bacterial homolog of actin, MreB, suggesting a mechanism for preventing SipA from interacting with bacterial MreB filaments . Remarkably, the pattern of SipA binding, which connects subunits on opposite actin strands and explains the stabilization of F-actin, is similar to that shown for a fragment of the giant muscle protein nebulin . We suggest that SipA is a bacterial structural mimic of muscle nebulin and nebulin-like proteins in non-muscle cells that are involved in the regulation of the actin-based cytoskeleton.

Vet Rec, 2002 May 25, 150(21), 649 - 54
Antimicrobial resistance in Salmonella isolated from animals and their environment in England and Wales from 1988 to 1999; Jones YE et al.; Resistance to 16 antimicrobial agents was monitored in 109,125 Salmonella cultures isolated from animals, their environment and feedstuffs between 1988 and 1999 . The sensitivity of the 6512 isolates of Salmonella enterica enterica serotype Dublin to all the antimicrobial agents tested varied from 98.2 per cent in 1997 to 99.7 per cent in 1990 and 1996 . In contrast, among 28,053 isolates of Salmonella enterica enterica serotype Typhimurium, there was a marked decrease in their sensitivity to all the antimicrobial agents tested, from 57.4 per cent in 1992 to 7.6 per cent in 1995, owing to the widespread occurrence in farm animals of S Typhimurium isolates of the definitive type DT104, resistant to ampicillin, sulphonamides, streptomycin, chloramphenicol and tetracyclines, although the percentage of sensitive isolates increased to 18.4 per cent in 1999, when the incidence of DT104 had decreased . Some isolates of DT104 also showed an increase in resistance to potentiated sulphonamides (2.4 per cent in 1989 to 19.2 per cent in 1999) and nalidixic acid (0 per cent in 1992, 3.8 per cent in 1995 to a peak of 16.9 per cent in 1998) . In 1996, 5.1 per cent of 1086 isolates of S Typhimurium from cattle and 35.9 per cent of 192 isolates of S Typhimurium from poultry showed resistance to nalidixic acid . Of the other 74,528 Salmonella isolates, the percentage of strains sensitive to all the antimicrobials tested decreased slightly from 88.2 per cent in 1988 to 70.6 per cent in 1996 and then increased slightly to 73.7 per cent in 1999 . The commonest of these other Salmonella serotypes was Salmonella Enteritidis (20,982), which remained predominantly susceptible (ranging from 81.4 to 97.4 per cent) during the study period . Few isolates were resistant to commonly used veterinary antimicrobials, for example, furazolidone, the use of which was banned in 1990, and the aminoglycoside, apramycin.

Comp Immunol Microbiol Infect Dis, 2002 May, 25(3), 159 - 72
Dynamics of a protective avian inflammatory response: the role of an IL-8-like cytokine in the recruitment of heterophils to the site of organ invasion by Salmonella enteritidis; Kogut MH; Increased resistance to Salmonella enteritidis (SE) organ infectivity in chickens can be conferred by the prophylactic administration of SE-immune lymphokines (ILK) . Resistance is associated with an enhanced heterophilic accumulation within 4 h of ILK injection . In these studies, the role of IL-8 in ILK-mediated heterophil recruitment during SE infections in young chickens was investigated . Heterophil accumulation was enhanced 2-4 h after the i.p . injection of both ILK and SE (ILK/SE) when compared to the control chicks . An i.p . injection of a rabbit polyclonal anti-human IL-8 antibody significantly (P < 0.01) reduced the accumulation of heterophils in the peritoneum after the injection of ILK/SE . Injections of preimmune rabbit IgG had no effect on peritoneal heterophil numbers . Within 2 h of injection of ILK/SE, a ten-fold increase in heterophil chemotactic activity was found in the peritoneal lavage fluid from these chicks compared to the saline control chicks . Pretreatment, with the anti-IL-8 antibody, of the peritoneal lavage fluids collected from the ILK/SE-treated chicks dramatically reduced this heterophil chemotactic activity . Treatment of the lavage fluids from all groups with preimmune IgG had no effect on heterophil chemotaxis . Additionally, pretreatment of ILK with the anti-human IL-8 antibody had no effect on heterophil chemotaxis . The results from these experiments suggest that IL-8 is produced locally by the host in response to both the SE infection and the ILK . With these studies, it was established that IL-8 is a major chemotactic factor produced by the host, which aids in mediating the ILK/SE-induced recruitment of heterophils to the site of SE invasion.

FEMS Immunol Med Microbiol, 2002 Jun 3, 33(2), 107 - 13
Production and characterization of monoclonal immunoglobulin A antibodies directed against Salmonella H:g,m flagellar antigen; Iankov ID et al.; Hybridomas were generated after intragastral immunization of BALB/c mice with live Salmonella suberu and subsequent fusion between isolated spleen lymphoblasts and myeloma cells . Three monoclonal antibodies (MAbs) of immunoglobulin A (IgA) isotype were selected and characterized . All of them were found to recognize the H:g epitope in enzyme-linked immunosorbent assay and immunoblotting but did not react with all H:g-expressing strains in slide agglutination test . All MAbs strongly agglutinated Salmonella enteritidis type strain and a large number of S . enteritidis clinical isolates . They were not bactericidal in the presence of complement . All hybridoma clones produced secretory IgA forms, which were found in the gastrointestinal tract of mice bearing hybridoma as a subcutaneous 'backpack' tumor or after intravenous application of purified MAbs . The IgA MAbs stability demonstrated in different tests together with their antigen specificity and strong agglutination ability make them a useful diagnostic tool for serotyping of Salmonella strains.

FEMS Immunol Med Microbiol, 2002 Jun 3, 33(2), 71 - 6
Monoclonal antibody of IgG isotype against a cross-reactive lipopolysaccharide epitope of Chlamydia and Salmonella Re chemotype enhances infectivity in L-929 fibroblast cells; Haralambieva IH et al.; A murine monoclonal antibody (MAb) 202D7 of IgG3 isotype recognizes a lipopolysaccharide (LPS) epitope of Chlamydia spp . and cross-reacts with the Re chemotype LPS of Salmonella and Escherichia coli . The antibody exhibits strong complement activating properties and stimulates phagocytosis of Salmonella enterica serovar Minnesota Re mutant by murine macrophages . Salmonella Re mutants are non-invasive for cell monolayers but still can enter and replicate in L-929 murine fibroblast cells . The entry of bacteria within the cells increases five-fold in the presence of MAb 202D7 . The antibody mediates attachment and enhances five-fold the infectivity of Chlamydia pneumoniae into L-929 cells, which suggests a possible IgG-mediated mechanism of entry and survival of the pathogen in fibroblast cells.

Biosens Bioelectron, 2002 Aug, 17(8), 676 - 84
Immunosensor for the differentiation and detection of Salmonella species based on a quartz crystal microbalance; Wong YY et al.; Immunosensors based on the microgravimetric quartz crystal microbalance (QCM) technique have been developed for the detection of Salmonella species from serogroups A, B and D . Salmonella serogroup-specific murine monoclonal antibodies, respectively, raised against these serogroups were immobilized onto the silver electrodes of piezoelectric (PZ) crystals by cross-linkage via glutaraldehyde (GA) to the electrode surfaces pre-coated with thin polyethyleneimine (PEI) layer . The specific immunosensors developed gave responses in linear ranges from 10(5) to 5x10(8) cells per ml with no significant interference from other strains of Salmonella and Escherichia coli up to 10(8) cells per ml . They showed good repeatability and excellent linear range, achieving detection limits down to 10(4) cells per ml with ability to distinguish different strains of Salmonella . These biosensors exhibited an exquisite specificity evidenced by their ability to discriminate antigens, the structures of which differ only by the isomeric form of di-deoxyhexose . The antibody-modified crystals showed no loss in activity over 4 days under storage at 4 degrees C.

Vet Microbiol, 2002 Jul 9, 87(3), 253 - 65
Prevalence of Escherichia coli O157:H7 prophage-like sequences among German Salmonella enterica serotype Typhimurium phage types and their use in detection of phage type DT104 by the polymerase chain reaction; Malorny B et al.; A 1.6kb DNA fragment identified by random amplifiable polymorphic DNA differentiation (RAPD) from a Salmonella enterica serotype Typhimurium phage type DT104 isolate was used to investigate the prevalence of the region in 160 DT104 isolates, 83 other epidemiological important S . Typhimurium phage types and 20 strains selected from 17 other Salmonella serotypes . PCR screening tests using two different primer-sets derived from the RAPD fragment's nucleotide sequence showed that 76% of the 160 DT104 isolates investigated, including subtypes DT104A, DT104B, DT104B low, DT104H and DT104L, reacted positively . High sensitivity was shown for DT104 strains expressing at least the penta-resistance pattern ACSSuT (97% of 104 strains tested) . DT104 susceptible strains showed only a sensitivity of 35% (17 strains tested) . In contrast, 83% of the 83 strains from the other S . Typhimurium phage types reacted negatively . Strains from five out of the 17 other serotypes showed a positive signal with one primer-set . The other primer-set exhibited only a positive reaction with one S . Dublin isolate . The analysis of a 2415bp extended sequence revealed homologies to genes encoded by Escherichia coli O157:H7 prophages, suggesting that the described region contains genes of a prophage specific for DT104 and related phage types.

Regul Toxicol Pharmacol, 2002 Apr, 35(2 Pt 1), 255 - 65
Safety assessment of DHA-rich microalgae from Schizochytrium sp; Hammond BG et al.; The purpose of this series of studies was to assess the genotoxic potential of docosahexaenoic acid-rich microalgae from Schizochytrium sp . (DRM) . DRM contains oil rich in highly unsaturated fatty acids (PUFAs) . Docosahexaenoic acid (DHA n-3) is the most abundant PUFA component of the oil ( approximately 29% w/w of total fatty acid content) . DHA-rich extracted oil from Schizochytrium sp . is intended for use as a nutritional ingredient in foods . All in vitro assays were conducted with and without mammalian metabolic activation . DRM was not mutagenic in the Ames reverse mutation assay using five different Salmonella histidine auxotroph tester strains . Mouse lymphoma suspension assay methodology was found to be inappropriate for this test material because precipitating test material could not be removed by washing after the intended exposure period and the precipitate interfered with cell counting . The AS52/XPRT assay methodology was not subject to these problems and DRM was tested and found not to be mutagenic in the CHO AS52/XPRT gene mutation assay . DRM was not clastogenic to human peripheral blood lymphocytes in culture . Additionally, DRM did not induce micronucleus formation in mouse bone marrow in vivo further supporting its lack of any chromosomal effects . Overall, the results of this series of mutagenicity assays support the conclusion that DRM does not have any genotoxic potential . (c) 2002 Elsevier Science (USA).

Environ Res, 2002 Mar, 88(3), 188 - 98
Interleukin-8 secretion from monocytic cell lines for evaluation of the inflammatory potential of organic dust; Allermann L et al.; The potential of organic dust to induce inflammation in vitro can be viewed as a crude measure of the total biologically active compounds in a dust sample . The purpose of this study was to further develop an in vitro screening method for evaluation of potential hazard related to low doses of dust exposure using two monocytic cell lines (U937 and THP-1) . Dust was obtained from schools in Copenhagen . U937 and THP-1 cells were stimulated with dust for 24 h and interleukin-8 secretion was measured . The initial slopes of the dose-response curves were used to calculate the inflammatory potential, or potency factor (PF), of the samples . In characterization of the method, lipopolysaccharide from Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella enteritidis were tested together with three glucans, nickel sulfate (NiSO(4)), methyl methacrylate (MMA), formaldehyde, and four surfactants . The PF values of LPSs in both monocytic assays ranked as follows: S . enteritidis> E . coli>K . pneumoniae/P . aeruginosa . The PF values of NiSO(4), MMA, formaldehyde, and the surfactants were zero or below . Using the THP-1 cell line, the PF values of dust samples were 30 times higher than when using the U937 cell line, and 7 times higher than when using the lung epithelial cell line (A549) . The high sensitivity of the THP-1 bioassay makes it potentially useful as a screening tool for hazard evaluation of dust from, e.g., the indoor environment . (c) 2002 Elsevier Science (USA).

Int J Food Microbiol, 2002 Jun 25, 76(3), 191 - 8
Enhanced antimicrobial effects of combination of lactate and diacetate on Listeria monocytogenes and Salmonella spp . in beef bologna; Mbandi E et al.; The antimicrobial activities of salts of organic acids such as lactate and acetate are well documented, but there is limited information on their effect when used in combination . We previously reported enhanced inhibition of Listeria monocvtogenes and Salmonella enterica serovar Enteritidis in sterile comminuted beef at 5 and 10 degrees C by combinations of sodium lactate (SL) (2.5%) and sodium diacetate (SDA) (0.2%) . The present study was undertaken to evaluate the inhibitory effect of these salts, alone and in combination, in ready-to-eat (RTE) meat . Single strains and six-strain mixtures of each of the pathogens ( approximately 3 log CFU/g) were tested in beef bologna during aerobic storage at 5 and 10 degrees C for up to 60 days . The growth rate of the six-strain mixture of Listeria was faster than that of the single strain (Scott A) in the lactate/diacetate-free product . While each of the salts delayed growth of the listeriae at 5 degrees C, the effect of their combination was listericidal for the single strain and listeriostatic for the six-strain mixture . Enhanced inhibition by the salt combination was also observed at 10 degrees C . Salmonella numbers declined to undetectable levels in the untreated meat product and in each of the treatments after 20-30 days . However, the decline was more rapid in meat with the combination of the salts during storage at both 5 and 10 degrees C . Each of the salts further delayed the growth of the background microflora during storage at 5 degrees C, with their combinations showing the most effect.

Rheumatology (Oxford), 2002 Jun, 41(6), 651 - 7
Invasion of Salmonella into human intestinal epithelial cells is modulated by HLA-B27; Saarinen M et al.; OBJECTIVE: To investigate the influence of the major histocompatibility complex (MHC) class I molecule HLA-B27 on (i) the invasion of Salmonella and Yersinia into human intestinal epithelial cells, (ii) the survival of intracellular Salmonella in these cells, and (iii) the production of certain inflammatory cytokines by the cells after Salmonella infection . METHODS: The human intestinal epithelial cell line Henle-407 was transfected with HLA-B27 DNA . These cells and HLA-B27-negative control cells were infected with Salmonella or Yersinia, and viable intracellular bacteria were determined as colony-forming units . Cytokine production was assayed with ELISA . RESULTS: Salmonella invaded HLA-B27-positive Henle cells in higher numbers than HLA-B27-negative control cells . However, HLA-B27 did not affect the invasion of Yersinia or the survival of the intracellular bacteria in these intestinal epithelial cells . Salmonella infection induced production of interleukin-8 (IL-8), IL-6 and monocyte chemotactic protein 1 (MCP-1) by Henle cells that was not affected by HLA-B27 in a specific way . CONCLUSIONS: These findings suggest that HLA-B27 enhances the invasion of Salmonella into intestinal epithelial cells . The interaction between bacteria and intestinal epithelial cells plays an important role during the early phases of ReA . HLA-B27-linked modulation of Salmonella invasion may lead to an increased load of Salmonella in intestinal tissue and thus increased susceptibility to reactive arthritis.

Circulation, 2002 Jun 4, 105(22), 2600 - 4
Prevention of inflammation-induced endothelial dysfunction: a novel vasculo-protective action of aspirin; Kharbanda RK et al.; BACKGROUND: Inflammation and infection may initiate and promote atherosclerosis or its complications by adverse effects on the vascular endothelium . The mechanisms by which aspirin reduces cardiovascular risk might involve anti-inflammatory actions or direct effects on the endothelium in addition to its antiplatelet action . We investigated the role of aspirin in modulating endothelial dysfunction induced by an experimental inflammatory stimulus . METHODS AND RESULTS: An inflammatory response was generated in healthy volunteers by Salmonella typhi vaccination . Venous occlusion plethysmography was used to assess resistance vessel responses (16 hours before and 8 hours after vaccination) to the endothelium-dependent dilator bradykinin (BK) and the endothelium-independent dilator glyceryl-trinitrate (GTN) . Twelve subjects were randomized to receive either aspirin 1.2 g orally or placebo 2 hours before vaccination . After vaccination alone there was suppression of the response to BK in the placebo group (P=0.01), with no change in response to GTN . In the aspirin group there was no change in the response to either BK or GTN after vaccination . Aspirin treatment prevented vaccine-induced elevation of interleukin-1 receptor antagonist but enhanced the generation of tumor necrosis factor-alpha compared with placebo . In an additional 5 individuals, local intrabrachial aspirin (10 mg/min for 15 minutes) failed to restore responses to BK after vaccination . CONCLUSIONS: Experimental inflammation produces endothelial dysfunction, which can be prevented by pretreatment with aspirin . Locally administered aspirin does not reverse vaccine-induced endothelial dysfunction once established . The protective effects of aspirin on inflammation-induced endothelial dysfunction may be through modulation of the cytokine cascade.

Am J Respir Crit Care Med, 2002 Jun 1, 165(11), 1516 - 25
Endotoxin induces respiratory failure and increases surfactant turnover and respiration independent of alveolocapillary injury in rats; Davidson KG et al.; Although endotoxin-induced acute lung injury is associated with inflammation, alveolocapillary injury, surfactant dysfunction, and altered lung mechanics, the precise sequence of these changes is polemic . We have studied the early pathogenesis of acute lung injury in spontaneously breathing anesthetized rats after intravenous infusion of Salmonella abortus equi endotoxin . The animals became hypoxic, and airway resistance, tissue resistance, lung elastance, and static compliance all deteriorated well before any change in alveolar neutrophils, macrophages, lung fluid (99mTc-labeled diethylenetriamine pentaacetic acid), or 125I-albumin flux, which were only appreciably increased at 8.5 hours . Lung elastance deteriorated before airway resistance, indicating that the compliance change was specific rather than caused by reduced lung volume . The subcellular and alveolar content of surfactant proteins A and B, cholesterol, disaturated phospholipids, and phospholipid classes remained normal in the face of a dramatic increase in the synthesis and turnover of 3H-disaturated phosphatidylcholine . Our findings indicate that the increase in surfactant disaturated phospholipid turnover reflects, at least in part, an approximately five-fold increase in "sigh frequency." We suggest that endotoxin has direct effects on tissue resistance and lung elastance independent of surfactant composition and that the initial respiratory failure results primarily from endotoxin-induced ventilation/perfusion mismatch independent of edema or alveolocapillary injury per se.

FEMS Microbiol Lett, 2002 May 7, 210(2), 251 - 5
Representational difference analysis uncovers a novel IS10-like insertion element unique to pathogenic strains of Yersinia enterocolitica; Iwobi A et al.; The method of suppressive subtractive hybridization was employed to map out genomic differences between the highly pathogenic Yersinia enterocolitica (Ye) biogroup 1B, serotype O:8 strain (WA-314) and the closely related apathogenic Y . enterocolitica biogroup 1A, serotype O:5 strain (NF-O) . A novel IS10-like element, IS1330, uncovered by this technique was found to be uniquely present in high copy numbers among the highly pathogenic Y . enterocolitica 1B strains, while a single copy of the element was found in the low pathogenic Ye biogroup 4 serotype O:3 strain . The 1321-bp repetitive element has 19-bp imperfect inverted terminal repeats and is bracketed by a 10-bp duplication of the target sequence . The predicted transposase shares high homology with the IS10 open reading frame of the large virulence plasmid pWR501, of Shigella flexneri, with IS10 transposase of Salmonella typhi, and with IS1999 (tnpA) of Pseudomonas aeruginosa . The IS1330 tnp gene is transcribed in vitro and in vivo in HeLa cells . At least one copy of IS1330 flanks the recently described chromosomal type III secretion cluster in Y . enterocolitica WA-314, O:8, and future studies should shed light on whether this novel transposase mediates transposition events in highly pathogenic Y . enterocolitica strains, thus enhancing the genetic plasticity of this species.

FEMS Microbiol Lett, 2002 May 7, 210(2), 245 - 9
Optimization of a rapid and sensitive identification system for Salmonella enteritidis by capillary electrophoresis with laser-induced fluorescence; Shintani T et al.; A system coupling capillary electrophoresis (CE) with a laser-induced fluorescence (LIF) system for the identification of Salmonella enteritidis was developed . Addition of an appropriate amount of sodium alginate and NaCl to the running buffer made it possible to obtain a reproducible sharp peak . Two fluorescent staining methods using a cell-permeable nucleic acid stain and a salmonellae-specific polyclonal antibody were adapted to the system . The CE-LIF successfully detected as few as three cells per injection from a pure culture of S . enteritidis . The CE-LIF system can be conveniently used for rapid and highly sensitive identification of S . enteritidis.

Int J Infect Dis, 2002 Mar, 6(1), 17 - 22
Changes in bloodstream infections in HIV-positive patients in a university hospital in Spain (1995-1997); Pedro-Botet ML et al.; OBJECTIVES: The Hospital Universitario Germans Trias i Pujol is a 600-bed center serving 700,000 inhabitants including 1800 patients with HIV infection in Catalonia (Spain) . Highly active antiretroviral therapy (HAART) became available at the end of 1996 . Thus, the period 1995 1997 was considered appropriate for evaluating possible epidemiological changes in bloodstream infections (BSI) in HIV-infected patients . METHODS: All significant bloodstream infections, including mycobacteremia and fungemia, observed in HIV-positive patients from January, 1995 to December, 1997 have been included in the study . RESULTS: One hundred and eighty six cases were evaluated, in whom a decrease in BSI was observed (68 in 1995, 86 in 1996, 32 in 1997) . Over time, we observed an improvement in the immunologic situation of the patients (1995: CD4 <50/mm3 73.8% vs 1997: CD4 <50/mm3 45.5% (P=0.05)) . The source of BSI was known in 80.7% of the episodes . BSI secondary to catheter and respiratory infections prevailed in 1995, whereas an increase in bacteremias related to intravenous drug use, with or without endocarditis, was seen in 1997 . The most frequent isolates were Mycobacterium avium intracellulare (23) (MAI), M . tuberculosis (20), Staphylococcus aureus (20), coagulase-negative staphylococci (16), Salmonella spp . (16) and Streptococcus pneumoniae (15) . In 1997, a decrease was observed in the isolation of Gram-negatives and Mycobacterium spp . with S . aureus and enterococci prevailing . CONCLUSIONS: The prevalence of bloodstream infections in HIV-positive patients has decreased since the introduction of HAART and the immunologic state has improved . Furthermore there is a trend to a decrease or disappearance of microorganisms, such as Pseudomonas spp., Mycobacterium tuberculosis, MAI or fungi related to severe immunosuppression . Lastly, bacteremia caused by the active use of intravenous drugs remains stable with the highest percentage in Spain.

Biochemistry, 2002 Jun 11, 41(23), 7519 - 27
Thermodynamics of aminoglycoside and acyl-coenzyme A binding to the Salmonella enterica AAC(6')-Iy aminoglycoside N-acetyltransferase; Hegde SS et al.; Kinetic and mechanistic studies on the chromosomally encoded aminoglycoside 6'-N-acetyltransferase, AAC(6')-Iy, of Salmonella enterica that confers resistance toward aminoglycosides have been previously reported {Magnet et al . (2001) Biochemistry 40, 3700-3709} . In the present study, equilibrium binding and the thermodynamic parameters of binding of aminoglycosides and acyl-coenzyme A derivatives to AAC(6')-Iy and of two mutants, C109A and the C109A/C70A double mutant, have been studied using fluorescence spectroscopy and isothermal titration calorimetry (ITC) . Association constants for different aminoglycosides varied greatly (4 x 10(4)-150 x 10(4)) while the association constants of several acyl-coenzyme A derivatives were similar (3.2 x 10(4)-4.5 x 10(4)) . The association constants and van't Hoff enthalpy changes derived from intrinsic protein fluorescence changes were in agreement with independently measured values from isothermal titration calorimetry studies . Binding of both aminoglycosides and acyl-coenzyme A derivatives is strongly enthalpically driven and revealed opposing negative entropy changes, resulting in enthalpy-entropy compensation . The acetyltransferase exhibited a temperature-dependent binding of tobramycin with a negative heat capacity value of 410 cal mol(-1) K(-1) . Isothermal titration studies of acetyl-coenzyme A and tobramycin binding to mutant forms of the enzyme indicated that completely conserved C109 does not play any direct role in the binding of either of the substrates, while C70 is directly involved in aminoglycoside binding . These results are discussed and compared with previous steady-state kinetic studies of the enzyme.

Pediatrics . 2002 Jun;109(6):e97.
Osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia, and immunodeficiency in a boy and incontinentia pigmenti in his mother; Dupuis-Girod S et al.; A child with X-linked osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia, and immunodeficiency (OL-EDA-ID) was recently reported . We report the clinical features of a second boy with this novel syndrome and his mother, who presented with signs of incontinentia pigmenti (IP) . The child had mild osteopetrosis without neurosensory complications, unilateral lymphedema of the left leg, and characteristic features of anhidrotic ectodermal dysplasia with sparse hair, facial dysmorphy, delayed eruption of teeth, and sweat gland abnormalities . He died at 18 months of severe immunodeficiency with multiple infections caused by Gram-negative (Salmonella enteritidis) and Gram-positive (Streptococcus pneumoniae) bacteria, nontuberculous mycobacteria (Mycobacterium kansasii), and fungi (Pneumocystis carinii) . His 30-year-old mother's medical history, together with residual cutaneous lesions, was highly suggestive of IP without neurologic impairment . In this patient with OL-EDA-ID, we detected the same NF-kappaB essential modulator stop codon hypomorphic mutation identified in the previous patient . The occurrence of the same clinical features in 2 unrelated patients with the same genotype demonstrates that OL-EDA-ID is a genuine clinical syndrome . The clinical and biological descriptions of the proband and his mother further corroborate the relationship between IP and EDA . Both syndromes are allelic and are associated with mutations in NF-kappaB essential modulator, with a genotype-phenotype correlation in hemizygous males . In contrast, loss-of-function mutations and hypomorphic mutations may cause IP in females.

J Chemother, 1991 Jan, 3 Suppl 1, 80 - 3
Antibiotic sensitivity of Salmonella strains from food-handlers in the period 1980-1988 in Italy; Gelosa L; Throughout the past nine years, between 1980 and 1988, we tested 1,205,257 food-handlers as Salmonella carriers in Milan . We isolated 20,286 Salmonella strains with annual average prevalence of 1.68%, fairly costant in recent years . The serotype isolated confirm the prevalence of minor Salmonella, such as S . thypimurium, S . panama, S . anatum, S . london, S . derby, S . infantis, S . heidelberg, S . bredeney, S . braenderup . The frequency of new strains decreased from 15 in 1980 to 1 in 1988 and these were infrequent serogroups . Salmonella strains isolated were generally sensitive to aminoglycoside antibiotics (tobramycin, netilmicin), while they were often resistant to rifampicin, aztreonam, and sometimes to cefuroxime and tetracycline with multiple-resistance.

J Antimicrob Chemother, 2002 Jun, 49(6), 1011 - 4
Unusual Salmonella enterica serotype Typhimurium isolate producing CMY-7, SHV-9 and OXA-30 beta-lactamases; Hanson ND et al.; Beta-lactam resistance in Salmonella isolates is increasing . This paper describes the combination of three different beta-lactamases, OXA-30, SHV-9 and CMY-7, expressed by an isolate of Salmonella enterica serotype Typhimurium . This is the first report of an isolate of Salmonella having both an extended-spectrum beta-lactamase and an AmpC beta-lactamase.

Appl Environ Microbiol, 2002 Jun, 68(6), 3114 - 20
Differences in growth of Salmonella enterica and Escherichia coli O157:H7 on alfalfa sprouts; Charkowski AO et al.; Sprout producers have recently been faced with several Salmonella enterica and Escherichia coli O157:H7 outbreaks . Many of the outbreaks have been traced to sprout seeds contaminated with low levels of human pathogens . Alfalfa seeds were inoculated with S . enterica and E . coli O157:H7 strains isolated from alfalfa seeds or other environmental sources and sprouted to examine growth of these human pathogens in association with sprouting seeds . S . enterica strains grew an average of 3.7 log(10) on sprouting seeds over 2 days, while E . coli O157:H7 strains grew significantly less, an average of 2.3 log(10) . The initial S . enterica or E . coli O157:H7 inoculum dose and seed-sprouting temperature significantly affected the levels of both S . enterica and E . coli O157:H7 on the sprouts and in the irrigation water, while the frequency of irrigation water replacement affected only the levels of E . coli O157:H7 . Colonization of sprouting alfalfa seeds by S . enterica serovar Newport and E . coli O157:H7 strains transformed with a plasmid encoding the green fluorescent protein was examined with fluorescence microscopy . Salmonella serovar Newport colonized both seed coats and sprout roots as aggregates, while E . coli O157:H7 colonized only sprout roots.

Appl Environ Microbiol, 2002 Jun, 68(6), 2737 - 44
Salmonella enterica serovar Typhimurium and Escherichia coli contamination of root and leaf vegetables grown in soils with incorporated bovine manure; Natvig EE et al.; Bovine manure, with or without added Salmonella enterica serovar Typhimurium (three strains), was incorporated into silty clay loam (SCL) and loamy sand (LS) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers . The S . enterica serovar Typhimurium inoculum was 4 to 5 log CFU/g in manure-fertilized soil . The conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily average Madison, Wis., weather conditions (hourly temperatures, rainfall, daylight, and humidity) for a 1 March or a 1 June manure application and subsequent vegetable growing seasons ending 9 August or 28 September, respectively . Core soil samples were taken biweekly from both inoculated and uninoculated soil beds in each chamber . Radishes, arugula, and carrots were planted in soil beds, thinned, and harvested . Soils, thinned vegetables, and harvested vegetables were analyzed for S . enterica serovar Typhimurium and Escherichia coli (indigenous in manure) . After the 1 March manure application, S . enterica serovar Typhimurium was detected at low levels in both soils on 31 May, but not on vegetables planted 1 May and harvested 12 July from either soil . After the 1 June manure application, S . enterica serovar Typhimurium was detected in SCL soil on 7 September and on radishes and arugula planted in SCL soil on 15 August and harvested on 27 September . In LS soil, S . enterica serovar Typhimurium died at a similar rate (P >or= 0.05) after the 1 June manure application and was less often detected on arugula and radishes harvested from this soil compared to the SCL soil . Pathogen levels on vegetables were decreased by washing . Manure application in cool (daily average maximum temperature of <10 degrees C) spring conditions is recommended to ensure that harvested vegetables are not contaminated with S . enterica serovar Typhimurium . Manure application under warmer (daily average maximum temperature >20 degrees C) summer conditions is not recommended when vegetable planting is done between the time of manure application and late summer . A late fall manure application will not increase the risk of contaminating vegetables planted the next spring, since further experiments showed that repeated freeze-thaw cycles were detrimental to the survival of S . enterica serovar Typhimurium and E . coli in manure-fertilized soil . The number of indigenous E . coli in soil was never significantly lower (P < 0.05) than that of S . enterica serovar Typhimurium, suggesting its usefulness as an indicator organism for evaluating the risk of vegetable contamination with manure-borne S . enterica serovar Typhimurium.

Medicina (B Aires), 2002, 62(2), 154 - 8
{Cytokines induced by experimental anti-tetanus immunization . Vaccine formulation effect}; Castro M et al.; Several factors are involved in the selective activation of T helper 1 or T helper 2 cells, such as the type of antigen-presenting cells involved in the immune response and the different physical characteristics of antigens . The aim of this work was to evaluate if adding other antigens to tetanus toxoid modifies the original immune response . BALB/c mice were immunized with tetanus and diphtheria toxoids associated with whole-cell Bordetella pertussis (DTPw vaccine), B . pertussis soluble antigens (DTPa vaccine) or Salmonella typhi plus DTPa (DTPaSt vaccine) . DTPw and DTPaSt immunization induced a T helper 1/T helper 2 (Th1/Th2) anti-tetanus response with gamma interferon and interleukin 5 production . DTPa immunization induced a Th2 response with production of interleukin 5 and interleukin 6 . Only DTPw vaccine induced higher levels of IL-12 in non-immunized mice . Our findings indicate that the co-injection of whole-cell antigens such as B . pertussis or S . typhi, modifies the anti-tetanus response shifting it from Th2 to Th1 type . However, the original Th2 immune response is not modified when the vaccine consists only of soluble antigens.

J Clin Microbiol, 2002 Jun, 40(6), 2074 - 8
DNA microarray-based typing of an atypical monophasic Salmonella enterica serovar; Garaizar J et al.; A multidrug-resistant fljB-lacking Salmonella enterica serovar {4,5,12:i:-} emerged in Spain in 1997 . We analyzed the genome from four strains of this serovar using a microarray containing almost all the predicted protein coding regions of serovar Typhimurium strain LT2, including the pSLT plasmid . Only a few differences from serovar Typhimurium LT2 were observed, suggesting the serovar to be Typhimurium as well . Six regions of interest were identified from the microarray data . Cluster I was a deletion of 13 genes, corresponding to part of the regulon responsible for the anaerobic assimilation of allantoin . Clusters II and IV were associated with the absence of the Fels-1 and Fels-2 prophage . Cluster III was a small group of Gifsy-1 prophage-related genes that appeared to be deleted or replaced . Cluster V was a deletion of 16 genes, including iroB and the operon fljAB, which is reflected in the serovar designation . Region VI was the gene STM2240, which appears to have an additional homologue in these strains . The regions spanning the deletions involving the allantoin operon and the fljAB operon were PCR amplified and sequenced . PCR across these regions may be an effective marker for this particular emergent serovar . While the microarray data for all isolates of the new serovar were essentially identical for all LT2 chromosomal genes, the isolates differed in their similarity to pSLT, consistent with the heterogeneity in plasmid content among isolates of the new serovar . Recent isolates have acquired a more-complete subset of homologues to this virulence plasmid . In general, microarrays can provide useful complementary data to other typing methods.

J Clin Microbiol, 2002 Jun, 40(6), 1924 - 9
Profile of Salmonella enterica subsp . enterica (subspecies I) serotype 4,5,12:i:- strains causing food-borne infections in New York City; Agasan A et al.; Strains of newly emerging Salmonella enterica subsp . enterica (subspecies I) serotype 4,5,12:i:- causing food-borne infections, including a large food poisoning outbreak (n = 86) characterized by persistent diarrhea (14% bloody), abdominal pain, fever, and headache, were examined . The organisms were found in the stool samples from the patients . The biochemical profile of the organisms is consistent with that of S . enterica subsp . I serotypes, except for decreased dulcitol (13%) and increased inositol (96%) utilization . Twenty-eight percent of the strains showed resistance to streptomycin, sulfonamides, or tetracycline only; all three antimicrobial agents; or these agents either alone or in combination with ampicillin, trimethoprim, and trimethoprim-sulfamethoxazole . None of the serotype 4,5,12:i:- strains showed resistance or decreased susceptibility to chloramphenicol or ciprofloxacin . On pulsed-field gel electrophoresis (PFGE), the strains showed 11 or 12 resolvable genomic fragments with 18 banding patterns and three PFGE profile (PFP) clusters (i.e., PFP/A, PFP/B, and PFP/C) . Seventy-five percent of the isolates fingerprinted were closely related (zero to three band differences; similarity {Dice} coefficient, 86 to 100%); 63% of these were indistinguishable from each other (PFP/A(1)) . PFP/A(1) was common to all strains from the outbreak and 11 hospital sources . Strains from six other hospitals shared clusters PFP/B and PFP/C . PFP/C(4), of the environmental isolate, was unrelated to PFP/A and PFP/B . Nine band differences (similarity coefficient, 61%) were noted between PFP/A(1) and PFP/E of the multidrug-resistant S . enterica subsp . enterica serotype Typhimurium definitive type 104 strains . Whether these emerging Salmonella strains represent a monophasic, Dul(-) variant of serotype Typhimurium or S . enterica subsp . enterica serotype Lagos or a distinct serotype of S . enterica subsp . I is not yet known . Some of the phenotypic and genotypic properties of the serotype 4,5,12:i:- strains are described here.

Indian J Pathol Microbiol, 2001 Oct, 44(4), 493 - 4
Rare co-existence of Salmonella typhi and mycobacteria tuberculosis in a psoas abscess--a case report; Kindo AJ et al.; We report a rare case of dual infection in a psoas abscess . Pus from the abscess grew Salmonella typhi and the abscess wall showed epitheloid granulomas giant cells, which we confirmed as tuberculosis by PCR . Such dual infection cases may be missed unless looked for since both these infections are common in our country.

Mutat Res, 2002 May 27, 517(1-2), 251 - 4
Antimutagenic mechanisms of Phyllanthus orbicularis when hydrogen peroxide is tested using Salmonella assay; Ferrer M et al.; Phyllanthus orbicularis is a medicinal plant, endemic to Cuba, whose aqueous extract has proven antiviral properties and antimutagenic activities against aromatic amines and hydrogen peroxide . In addition, this plant extract presents antioxidant activity . In this paper, using the Salmonella assay with the experimental approaches of co-incubation, pre- and post-treatments, it is shown that the P . orbicularis extract protects bacterial cells from oxidative damage and mutation by some intracellular mechanism, irrespective of its antioxidant activity.

J Vet Diagn Invest, 2002 May, 14(3), 211 - 8
Evaluation and extension of the cusum technique with an application to Salmonella surveillance; Carpenter TE; The cumulative sum (cusum) technique was examined for its use in a disease surveillance system for detecting temporal clusters of events . Optimal technique parameters were derived for scenarios not previously considered . Simulation modeling produced results that evaluated deviations from predefined rate increases . The cusum technique was less prone to false alarms and more efficient at detecting large rate increases than previously reported . As demonstrated using data obtained from a Salmonella surveillance system operated by a state animal diagnostic laboratory system, the cusum technique could provide early warning of an epidemic problem.

Poult Sci, 2002 May, 81(5), 715 - 20
Microbial contamination in inoculated shell eggs: I . Effects of layer strain and hen age; Jones DR et al.; Three Ottawa control strains and a current commercial laying stock were reared and housed under identical environmental and management conditions . Eggs were collected from each strain when hens were 32, 45, 58, 71, and 84 wk of age . The eggs were inoculated with Salmonella enteritidis (SE), Pseudomonasfluorescens (PF), or a combination of the two . After storage at 26 C, bacterial counts were obtained from the exterior shell surfaces (rinse), air cell, egg contents, and shell structure . SE and PF survived at different rates on the shell surface with as much as a 1 log difference during a given collection period . Egg content counts tended to be higher than eggshell counts in PF, whereas the opposite was true for SE . These data suggest that PF is a primary invader of eggs that is more capable of contaminating egg contents through the shell membranes than SE . The PF and SE data suggest that bacterial contamination of air cells, shells, and egg contents is more easily achieved in eggs from older hens than from younger hens . There were also differences between the strains . Control Strain 10 consistently maintained a lower level of contamination for both organisms in each sampling location . The overall results of this study suggest that genetic selection has altered the ability of eggs to resist microbial contamination and that screening for microbial integrity should be considered in the selection process among the laying egg breeders.

Poult Sci, 2002 May, 81(5), 657 - 63
Microsatellites linked to Salmonella enterica Serovar Enteritidis burden in spleen and cecal content of young F1 broiler-cross chicks; Kaiser MG et al.; Contamination of poultry and poultry products by Salmonella enterica Serovar Enteritidis (SE) continues to be problematic even though biosafety management practices have aided in reduction of the SE burden . Identification of molecular markers linked to disease resistance loci would further reduce SE burden by enabling selection for genetic resistance . The objectives of this study were therefore to evaluate specific genomic regions for resistance to SE burden in young broiler-cross chicks and to evaluate the interaction of allele with dam line and sex . Three hatches of F1 chicks were produced by crossing sires from a broiler breeder male line with hens from three highly inbred lines (Fayoumi 15.2, and MHC-congenic G-B1 and G-B2 Leghorn) . At 1 d of age, the chicks were intraesophageally inoculated with SE phage type 13a . Spleen and cecal content samples were harvested at 1 wk, and the levels of SE were quantified by serial plate dilution . Each of the F1 chicks was genotyped with four microsatellites that had previously been shown to be linked to antibody response to SE vaccine . All four microsatellites had a significant (P < or = 0.05) main effect or interaction with dam line or sex on the level of SE in spleen and cecal contents.

Proc Natl Acad Sci U S A, 2002 May 28, 99(11), 7675 - 80
Inorganic polyphosphate is essential for long-term survival and virulence factors in Shigella and Salmonella spp; Kim KS et al.; The importance of inorganic polyphosphate (poly P) and poly P kinase (PPK), the enzyme principally responsible for its synthesis, has been established previously for stationary-phase survival of Escherichia coli and virulence in Pseudomonas aeruginosa . The gene (ppk) that encodes PPK is highly conserved among many bacterial pathogens, including Shigella and Salmonella spp . In view of the phylogenetic similarity of the enteropathogens and the frequency with which virulence factors are expressed in stationary phase, the ppk gene of pathogenic Shigella flexneri, Salmonella enterica serovar Dublin, and Salmonella enterica serovar typhimurium have been cloned and deleted . In some of these mutants lacking ppk, the phenotypes included features indicative of decreased virulence such as: (i) growth defects, (ii) defective responses to stress and starvation, (iii) loss of viability, (iv) polymyxin sensitivity, (v) intolerance to acid and heat, and (vi) diminished invasiveness in epithelial cells . Thus PPK may prove, as it has with P . aeruginosa, to be an attractive target for antibiotics, with low toxicity because PPK is not found in higher eukaryotes.

Proc Natl Acad Sci U S A, 2002 May 28, 99(11), 7652 - 7
Genomewide identification of proteins secreted by the Hrp type III protein secretion system of Pseudomonas syringae pv . tomato DC3000; Petnicki-Ocwieja T et al.; The ability of Pseudomonas syringae pv . tomato DC3000 to be pathogenic on plants depends on the Hrp (hypersensitive response and pathogenicity) type III protein secretion system and the effector proteins it translocates into plant cells . Through iterative application of experimental and computational techniques, the DC3000 effector inventory has been substantially enlarged . Five homologs of known avirulence (Avr) proteins and five effector candidates, encoded by genes with putative Hrp promoters and signatures of horizontal acquisition, were demonstrated to be secreted in culture and/or translocated into Arabidopsis in a Hrp-dependent manner . These 10 Hrp-dependent outer proteins (Hops) were designated HopPtoC (AvrPpiC2 homolog), HopPtoD1 and HopPtoD2 (AvrPphD homologs), HopPtoK (AvrRps4 homolog), HopPtoJ (AvrXv3 homolog), HopPtoE, HopPtoG, HopPtoH, HopPtoI, and HopPtoS1 (an ADP-ribosyltransferase homolog) . Analysis of the enlarged collection of proteins traveling the Hrp pathway in P . syringae revealed an export-associated pattern of equivalent solvent-exposed amino acids in the N-terminal five positions, a lack of Asp or Glu residues in the first 12 positions, and amphipathicity in the first 50 positions . These characteristics were used to search the unfinished DC3000 genome, yielding 32 additional candidate effector genes that predicted proteins with Hrp export signals and that also possessed signatures of horizontal acquisition . Among these were genes encoding additional ADP-ribosyltransferases, a homolog of SrfC (a candidate effector in Salmonella enterica), a catalase, and a glucokinase . One ADP-ribosyltransferase and the SrfC homolog were tested and shown to be secreted in a Hrp-dependent manner . These proteins, designated HopPtoS2 and HopPtoL, respectively, bring the DC3000 Hrp-secreted protein inventory to 22.

Cardiovasc Res, 2002 Jun, 54(3), 684 - 93
Inhibition of nuclear factor-kappaB activation by IRFI 042, protects against endotoxin-induced shock; Altavilla D et al.; BACKGROUND: The aim of our study was to investigate the effect of IRFI 042, a novel dual vitamin E-like antioxidant, on nuclear factor-kappaB (NF-kappaB) activation, TNF-alpha gene priming and on the release of the mature protein during endotoxin shock . METHODS: Endotoxin shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg kg(-1) of Salmonella enteritidis lipopolysaccharide (LPS) . Survival rate, mean arterial blood pressure, serum TNF-alpha and plasma malondialdehyde (MAL) levels were investigated . We then evaluated in the liver TNF-alpha mRNA levels, NF-kappaB binding activity and the inhibitory protein IkappaBalpha . Moreover we studied in LPS stimulated (50 microg ml(-1)) peritoneal macrophages (Mphi), NF-kappaB activation, cytoplasmic IkappaB-alpha degradation, the message for TNF-alpha, and TNF-alpha and MAL levels . RESULTS: LPS administration reduced survival rate (0%, 72 h after LPS administration), decreased mean arterial blood pressure, augmented serum TNF-alpha (60+/-11 ng ml(-1)) and enhanced plasma malondialdehyde (MAL) levels (55+/-7.1 nmol l(-1)) . LPS shocked rats also had increased TNF-alpha mRNA levels, augmented liver NF-kappaB binding activity in the nucleus and decreased levels of the inhibitory protein IkappaBalpha . In addition, in vitro LPS stimulation (50 microg ml(-1)) significantly induced NF-kappaB activation and cytoplasmic IkappaBalpha degradation in Mphi, enhanced TNF-alpha mRNA levels and increased Mphi TNF-alpha and MAL . Treatment with IRFI 042 (20 mg kg(-1), i.v., 5 min after endotoxin challenge) protected against LPS-induced lethality (90% survival rate 24 h and 80% survival rate 72 h after LPS injection, respectively), reduced hypotension, blunted plasma MAL (9.0+/-0.9 nmol l(-1)) and decreased serum TNF-alpha (15+/-3 ng ml(-1)) . The antioxidant also inhibited the loss of IkappaBalpha protein from the hepatic cytoplasm, blunted the increased NF-kappaB binding activity in the liver and decreased hepatic liver mRNA for TNF-alpha . Furthermore 'in vitro' IRFI 042 (50 microM) significantly inhibited activation of NF-kappaB through inhibition of IkappaBalpha degradation, reduced the amount of TNF-alpha mRNA, decreased LPS-induced TNF-alpha release and blunted lipid peroxidation (MAL) in LPS stimulated Mphi . CONCLUSIONS: These data suggest that IRFI 042 blocks the activation of NF-kappaB, reduces TNF-alpha mRNA levels, and finally reverses endotoxic shock.

Arch Med Res, 2002 May-Jun, 33(3), 313 - 5
Salmonella infection-associated acute rhabdomyolysis . Some pathogenic considerations; Brncic N et al.; Rhabdomyolysis is a syndrome characterized by extended myolysis, elevation of serum aminotransferases and creatine kinase, and myoglobinuria . It is a rare but well-established complication of a spectrum of infectious diseases . Salmonella infections have been connected with this syndrome as well . We present here the case of a 58-year-old female affected by Charcot-Marie-Tooth (CMT) disease, a type of hereditary neuropathy, who presented with acute renal failure and rhabdomyolysis syndrome in the course of Salmonella infantis gastroenteritis . We formed some considerations on the pathogenesis of rhabdomyolysis in this specific setting based on certain experimental works on the Salmonella pathogenic cycle . We concluded that the calcium-dependent mechanism coupled with a predisposing factor might be of major significance in the development of this complication.

J Food Prot, 2002 May, 65(5), 848 - 52
Reduction of Escherichia coli O157:H7 and Salmonella spp . on laboratory-inoculated mung bean seed by chlorine treatmentt; Fett WF; Three U.S . outbreaks of foodborne illness due to consumption of contaminated raw mung bean sprouts occurred in the past 2 years and were caused by Salmonella Enteritidis . The original source of the pathogens is thought to have been the seed . The aim of this study was to determine whether treatment with aqueous chlorine would eliminate the pathogens from mung bean seed inoculated in the laboratory with four-strain cocktails of Escherichia coli O157:H7 and Salmonella spp . Treatments (for 5, 10, or 15 min) with buffered (500 mM potassium phosphate, pH 6.8) or unbuffered solutions containing 0.3 or 3.0% (wt/vol) Ca(OCl)2 were tested . In order to mimic common commercial practice, seed was rinsed before and after treatment with sterile tap water . Treatment for 15 min with buffer (500 mM potassium phosphate, pH 6.8) or sterile water in combination with the seed rinses resulted in maximum reductions of approximately 3 log10 CFU/g . The largest reductions (4 to 5 log10 CFU/g) for the chlorine treatments in combination with the rinses were obtained after treatment with buffered 3.0% (wt/vol) Ca(OCl)2 for 15 min . Treatment of mung bean seed for 15 min with unbuffered or buffered 3.0% (wt/vol) Ca(OCl)2 did not adversely affect germination . Even though treatments with 3% (wt/vol) Ca(OCl)2 in combination with the water rinses were effective in greatly reducing the populations of both bacterial pathogens, these treatments did not result in the elimination of the pathogens from laboratory-inoculated seed.

J Food Prot, 2002 May, 65(5), 814 - 9
R-phycoerythrin as a time-temperature integrator to verify the thermal processing adequacy of beef patties; Smith SE et al.; The objective of this study was to relate R-phycoerythrin (PE) fluorescence decay to the inactivation of Salmonella in beef patties cooked using adequate and inadequate thermal processes as defined by the U.S . Department of Agriculture (USDA) safe harbor requirements and lethality standards . Ground beef containing 4.8 or 19.1% fat was inoculated with an eight-strain cocktail of Salmonella and formed into 113-g patties . Capillary tubes containing PE in borate buffer at pH 9.0 were attached to a thermocouple and inserted horizontally into the patties . Patties (n = 43) were cooked on a grill maintained at 177 degrees C for 6 to 13 min and reached internal temperatures ranging from 57 to 77 degrees C . Patties were analyzed for Salmonella survivors and for fluorescence decay of PE . The thermal lethality of each process was calculated at a reference temperature of 65 degrees C . Twenty-four of the 43 high-fat patties met the USDA safe harbor regulations, with thermal lethalities of >66 s, whereas only 20 of these patties met the proposed 5-log10 lethality standard . Three of the 20 low-fat patties that met USDA regulations did not meet the proposed lethality standard . A normalized PE fluorescence value of about 0.3 (confidence interval = 99%) indicated that patties had been processed sufficiently to reduce Salmonella by 5 log10 cycles . PE has the potential for use as a marker to verify processing adequacy in food-processing plants and in other settings in which the use of the target pathogen is inappropriate.

J Food Prot, 2002 May, 65(5), 768 - 73
Antibiotic resistance of Salmonella spp . from animal sources in Spain in 1996 and 2000; Usera MA et al.; Emergence of resistant and multiresistant bacteria has become an important worldwide sanitary problem . International agencies recommend improving resistance surveillance studies in not only human but also animal origin strains . Because of its ubiquitous characteristics and zoonotic agent consideration, Salmonella spp . can be used as a good indicator microorganism for resistance surveillance studies . Salmonella spp . strains from animal sources isolated in 1996 (107) and 2000 (474) in Spain were tested against 12 different antimicrobials agents, using the disc diffusion method . Results were interpreted following the NCCLS criteria . Data showed that Salmonella spp . strains (61.7% in 1996 and 81.5% in 2000) were resistant to at least one antibiotic . Pig-related strains were considerably more resistant than strains from other sources . Enteritidis serotype was less resistant than other serotypes, except for ampicillin in 1996 (50% resistant) and nalidixic acid in 2000 (65.1% resistant) . An emergent monophasic serotype, 4,5,12:i:-, first detected in 1997 in Spain was 100% resistant and 90% multiresistant . Typhimurium serotype was the most common Salmonella serotype from animal sources in both years . It was widely distributed among animals and was among the serotypes with a higher degree of resistance . The ampicillin, chloramphenicol, sulfonamides, streptomycin, and tetracycline resistance pattern, commonly associated with Salmonella serotype Typhimurium DT 104, had spread among other Typhimurium phage types and other Salmonella serotypes . Salmonella spp . strains isolated from feeding stuffs were considerably more susceptible than animal source strains, suggesting that the high Salmonella spp . resistance percentage was probably due to the use of antibiotics in animal farms rather than the consumption of contaminated feeding stuffs.

J Food Prot, 2002 May, 65(5), 742 - 5
Serotype tracking of Salmonella through integrated broiler chicken operations; Bailey JS et al.; The widespread presence of Salmonella in all phases of broiler chicken production and processing is well documented . However, little information is available to indicate the identity and movement of specific serotypes of Salmonella through the different phases of an integrated operation . In this study, samples were collected from the breeder farm, from the hatchery, from the previous grow-out flock, from the flock during grow-out, and from carcasses after processing . Salmonella were recovered from 6, 98, 24, 60, and 7% of the samples, respectively, in the first trial and from 7, 98, 26, 22, and 36% of the samples, respectively, in the second trial . Seven different serotypes were identified in the first trial, and 12 different serotypes were identified in the second trial . For both trials there was poor correlation between the serotypes found in the breeder farms and those found in the hatchery . This finding and the fact that similar serotypes were found in the hatchery in both trials suggests that there was an endemic population of Salmonella in the hatchery . An association between the serotypes found in the hatchery and those found on the final processed carcasses was observed in both trials . This study confirms that a successful intervention program for broiler production operations must be multifaceted, with one component being disinfection in the hatchery.

J Bacteriol, 2002 Jun, 184(12), 3329 - 37
Substrate recognition properties of oligopeptidase B from Salmonella enterica serovar Typhimurium; Morty RE et al.; Oligopeptidase B (OpdB) is a serine peptidase broadly distributed among unicellular eukaryotes, gram-negative bacteria, and spirochetes which has emerged as an important virulence factor and potential therapeutic target in infectious diseases . We report here the cloning and expression of the opdB homologue from Salmonella enterica serovar Typhimurium and demonstrate that it exhibits amidolytic activity exclusively against substrates with basic residues in P(1) . While similar to its eukaryotic homologues in terms of substrate specificity, Salmonella OpdB differs significantly in catalytic power and inhibition and activation properties . In addition to oligopeptide substrates, restricted proteolysis of histone proteins was observed, although no cleavage was seen at or near residues that had been posttranslationally modified or at defined secondary structures . This supports the idea that the catalytic site of OpdB may be accessible only to unstructured oligopeptides, similar to the closely related prolyl oligopeptidase (POP) . Salmonella OpdB was employed as a model enzyme to define determinants of substrate specificity that distinguish OpdB from POP, which hydrolyzes substrates exclusively at proline residues . Using site-directed mutagenesis, nine acidic residues that are conserved in OpdBs but absent from POPs were converted to their corresponding residues in POP . In this manner, we identified a pair of glutamic acid residues, Glu(576) and Glu(578), that define P(1) specificity and direct OpdB cleavage C terminal to basic residues . We have also identified a second pair of residues, Asp(460) and Asp(462), that may be involved in defining P(2) specificity and thus direct preferential cleavage by OpdB after pairs of basic residues.

J Bacteriol, 2002 Jun, 184(12), 3203 - 13
mig-14 is a Salmonella gene that plays a role in bacterial resistance to antimicrobial peptides; Brodsky IE et al.; It was previously demonstrated that the mig-14 gene of Salmonella enterica serovar Typhimurium is necessary for bacterial proliferation in the liver and spleen of mice following intragastric inoculation and that mig-14 expression, which is induced within macrophages, is under the control of the global regulator PhoP . Here we demonstrate that the mig-14 promoter is induced by growth in minimal medium containing low magnesium or acidic pH, consistent with regulation by PhoP . In addition, mig-14 is strongly induced by polymyxin B, protamine, and the mammalian antimicrobial peptide protegrin-1 . While phoP is necessary for the induction of mig-14 in response to protamine and protegrin, mig-14 is still induced by polymyxin B in a phoP background . We also demonstrate that mig-14 is necessary for resistance of S . enterica serovar Typhimurium to both polymyxin B and protegrin-1 . Gram-negative resistance to a variety of antimicrobial peptides has been correlated with modifications of lipopolysaccharide structure . However, we show that mig-14 is not required for one of these modifications, the addition of 4-aminoarabinose to lipid A . Additionally, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of wild-type and mig-14 lipopolysaccharide also shows no detectable differences between the two strains . Therefore, mig-14 contributes to Salmonella resistance to antimicrobial peptides by a mechanism that is not yet fully understood.

J Bacteriol, 2002 Jun, 184(12), 3159 - 66
SitABCD is the alkaline Mn(2+) transporter of Salmonella enterica serovar Typhimurium; Kehres DG et al.; MntH, a bacterial homolog of the mammalian natural resistance-associated macrophage protein 1 (Nramp1), is a primary Mn(2+) transporter of Salmonella enterica serovar Typhimurium and Escherichia coli . S . enterica serovar Typhimurium MntH expression is important for full virulence; however, strains carrying an mntH deletion are only partially attenuated and display no obvious signs of Mn(2+) deficiency . We noted that promoter sequences for mntH and for the putative Fe(2+) transporter sitABCD appeared to have the same regulatory element responsive to Mn(2+) and so hypothesized that sitABCD could transport Mn(2+) with high affinity . We have now characterized transport by SitABCD in S . enterica serovar Typhimurium using (54)Mn(2+) and (55)Fe(2+) and compared its properties to those of MntH . SitABCD mediates the influx of Mn(2+) with an apparent affinity (K(a)) identical to that of MntH, 0.1 microM . It also transports Fe(2+) but with a K(a) 30 to 100 times lower, 3 to 10 microM . Inhibition of (54)Mn(2+) transport by Fe(2+) and of (55)Fe(2+) transport by Mn(2+) gave inhibition constants comparable to each cation's K(a) for influx . Since micromolar concentrations of free Fe(2+) are improbable in a biological system, we conclude that SitABCD functions physiologically as a Mn(2+) transporter . The cation inhibition profiles of SitABCD and MntH are surprisingly similar for two structurally and energetically unrelated transporters, with a Cd(2+) K(i) of approximately 1 microM and a Co(2+) K(i) of approximately 20 microM and with Ni(2+), Cu(2+), and Fe(3+) inhibiting both transporters only at concentrations of >0.1 mM . The one difference is that Zn(2+) exhibits potent inhibition of SitABCD (K(i) = 1 to 3 microM) but inhibits MntH weakly (K(i) > 50 microM) . We have previously shown that MntH transports Mn(2+) most effectively under acidic conditions . In sharp contrast, SitABCD has almost no transport capacity at acid pHs and optimally transports Mn(2+) at slightly alkaline pHs . Overall, coupled with evidence that each transporter is multiply but distinctly regulated at the transcriptional level, the distinct transport properties of MntH versus SitABCD suggest that each transporter may be specialized for Mn(2+) uptake in different physiological environments.

What Is Functional Genomics?, What Is Biofilm?, What Is Pcr?, What Is MIC?, What Is Genetic Engineering?, i, Microbe, n, Microbiology, s, Microorganism, o, Bacterium, o, Microbes, s, Meningococcus, r, Multidrug resistant, r, Haemophilus, r, Staphylococcus, a, Staphylococcus, n, Antibiotics, o, Haemophilus, n, Vibriosis, s, Lactobacillus, n, Staphylococcus, e, Anaerobic bacteria, o, Lactobacillus, s, Salmonella typhimurium, s, Bacteriophages, n, Thermophiles, i, Prokaryotes, e, Eubacter, o, Antimicrobials, s, Escherichia coli, s, Clostridia, i, Pasteurella

Scientific Publications - Work Done by Microbiology Reader Bioscreen C
Agricultural Microbiology Anaerobic Microbiology Antimicrobial Susceptibility Artificial Atmosphere Bioassay of Antibiotics Biofilm Microbiology Bioreactor Technology Biotechnology Cell Biology Clinical Microbiology Environmental Microbiology Experiments with Yeast	Fermentation Food Microbiology Functional Genomics Gene Technology Growth Media Development Growth Rate and Lag Time Industrial Microbiology Medical/Pharmaceutical Field Microbiological Assay Microbiological Research Microbiology of Cosmetics go to a specific theme...	Military Microbiology Molecular Microbiology Mutagenicity and Genotoxicity Oral Microbiology Patents Postantibiotic Studies Soil Microbiology Spore Microbiology Veterinary Microbiology Waste/Wastewater Treatment Water Microbiology Wine Microbiology

� 2005 Transgalactic Ltd (manufacturer of Bioscreen C software) | Privacy Statement | P.O. Box 1393, 00101 Helsinki, Finland, phone: +358 9 85172920, fax: +358 9 8749481, e-mail: microbiology@bionewsonline.com

Last modified: May 25, 2005