Salmonella

Eur J Immunol, 2000 Mar, 30(3), 944 - 53
Dual role for macrophages in vivo in pathogenesis and control of murine Salmonella enterica var . Typhimurium infections; Wijburg OL et al.; Salmonella spp . are regarded as facultative intracellular bacterial pathogens which are found inside macrophages (Mphi) after i . v . infection . It is generally assumed that Mphi restrict the replication of the bacteria during infection . In this study we examined the in vivo activities of Mphi during experimental S . typhimurium infections, using a selective liposome-based Mphi elimination technique . Unexpectedly, elimination of Mphi prior to infection with virulent S . typhimurium decreased morbidity and mortality, suggesting that Mphi mediate the pathology caused by S . typhimurium . Removal of Mphi) during vaccination with attenuated S . typhimurium did not affect protection against challenge with virulent S . typhimurium, suggesting that Mphi are not required for the induction of protective immunity and that other cells must function as antigen-presenting cell to elicit T cell-mediated protection . However, Mphi appeared to be important effectors of protection against challenge infection since elimination of Mphi from vaccinated mice prior to challenge infection with virulent S . typhimurium significantly decreased protection . These results enhance our understanding of the control of S . typhimurium growth in vivo, and moreover suggest that Mphi play a major role in the pathology of virulent S . typhimurium infections . As such, these cells may present a novel target for therapeutic intervention.

Eur J Immunol, 2000 Mar, 30(3), 768 - 77
Modulation of host immune responses stimulated by Salmonella vaccine carrier strains by using different promoters to drive the expression of the recombinant antigen; Medina E et al.; We evaluated whether immune responses stimulated by Salmonella vaccine carriers can be modulated by using different promoters to drive antigen expression . Mice were orally immunized with strains transfected with plasmids carrying beta-galactosidase (beta-gal) under the control of either a constitutive or an in vivo-activated promoter . While alpha-gal-reactive IgG1, IgG2a, IgG2b and IgG3 were detected in sera of mice immunized with Salmonella expressing constitutively beta-gal, higher titers dominated by IgG2a and IgG2b were detected in sera when the in vivo-activated promoter was used . beta-gal-specific proliferative responses of spleen-derived CD4+ T lymphocytes were similar in both groups . However, CD4+ T lymphocytes from mice immunized with the constitutive promoter secreted IL-4, IL-5, IL-6, IL-10 and IFN-gamma (Th1/Th2 pattern), whereas CD4+ cells mainly secreted IFN-gamma (Th1 pattern) when the second construct was used . The spleens of all immunized mice contained beta-gal-reactive CD8+ CTL precursors . The vaccine prototypes were tested for their capacity to control seeding and/or development within the lung of an intravenously delivered aggressive fibrosarcoma transfected with beta-gal . Reduced metastasis and significantly increased mean survival times were observed in all vaccinated mice . However, protection was improved when the carrier expressed beta-gal upon infection (80 % versus 50% survival, p < 0.05).

Kansenshogaku Zasshi, 2000 Feb, 74(2), 143 - 9
Salmonella paratyphi A is more genetically homogeneous than Salmonella typhi, as indicated by pulsed-field gel electrophoresis; Matsumoto M et al.; We analyzed 18 Salmonella Paratyphi A and 12 Salmonella Typhi isolates from domestic and imported cases in Aichi, Japan, using pulsed-field gel electrophoresis . Paratyphoid fever cases have increased and outbreaks of Salmonella Paratyphi A occasionally occur in Japan, but S . Paratyphi A has not been extensively analyzed . Our study suggests significant genetic homogeneity among Salmonella Paratyphi A belonging to different phage types, which is in contrast to the genetic heterogeneity of Salmonella Typhi . These results suggest that a limited number of clones are responsible for paratyphoid fever.

J Microbiol Methods, 2000 Mar, 40(1), 33 - 8
Differentiation of Salmonella enterica serotype gallinarum biotype pullorum from biotype gallinarum by analysis of phase 1 flagellin C gene (fliC); Kwon HJ et al.; Salmonella enterica serotype gallinarum biotype gallinarum and biotype pullorum are non-motile and pathogenic avian strains . Biotype gallinarum causes fowl typhoid and biotype pullorum is the cause of pullorum disease in chickens . The two biotypes could be differentiated based on biochemical characteristics . However, conventional culture and biochemical assays are time-consuming, laborious and need sterile laboratory practices . Although the two biotypes, gallinarum and pullorum are non-motile, they possess the phase 1 flagellin C gene . The variable regions of the flagellin C gene from 41 biotype pullorum and 52 biotype gallinarum were amplified by colony-PCR and analyzed by single strand conformational polymorphism (SSCP) method . Differences in SSCP electrophoretic patterns were confirmed by nucleotide sequencing . In addition, PCR-RFLP with Hinp1I was also successfully applied to differentiate the two biotypes . These results suggested that the variable regions of fliC could be used as a genetic marker to differentiate biotype gallinarum from biotype pullorum.

Clin Orthop, 2000 Mar, (372), 250 - 3
Salmonella osteomyelitis secondary to iguana exposure; Nowinski RJ et al.; Salmonella osteomyelitis is a rare condition that has been associated with patients having hemoglobinopathies or immunosuppression . Healthy patients with no underlying medical history have been known to have Salmonella osteomyelitis develop . Salmonella infection secondary to reptile exposure is an increasing condition in the United States . Several manifestations of salmonellosis have been described in the literature, but no cases of reptile associated bone or joint infections have been reported . The authors present a case of a 7-month-old girl who contracted Salmonella osteomyelitis of her proximal humerus with septic arthritis of the glenohumeral joint secondary to iguana exposure.

Proteins, 2000 Apr 1, 39(1), 89 - 101
Plasticity and steric strain in a parallel beta-helix: rational mutations in the P22 tailspike protein; Schuler B et al.; By means of genetic screens, a great number of mutations that affect the folding and stability of the tailspike protein from Salmonella phage P22 have been identified . Temperature-sensitive folding (tsf) mutations decrease folding yields at high temperature, but hardly affect thermal stability of the native trimeric structure when assembled at low temperature . Global suppressor (su) mutations mitigate this phenotype . Virtually all of these mutations are located in the central domain of tailspike, a large parallel beta-helix . We modified tailspike by rational single amino acid replacements at three sites in order to investigate the influence of mutations of two types: (1) mutations expected to cause a tsf phenotype by increasing the side-chain volume of a core residue, and (2) mutations in a similar structural context as two of the four known su mutations, which have been suggested to stabilize folding intermediates and the native structure by the release of backbone strain, an effect well known for residues that are primarily evolved for function and not for stability or folding of the protein . Analysis of folding yields, refolding kinetics and thermal denaturation kinetics in vitro show that the tsf phenotype can indeed be produced rationally by increasing the volume of side chains in the beta-helix core . The high-resolution crystal structure of mutant T326F proves that structural rearrangements only take place in the remarkably plastic lumen of the beta-helix, leaving the arrangement of the hydrogen-bonded backbone and thus the surface of the protein unaffected . This supports the notion that changes in the stability of an intermediate, in which the beta-helix domain is largely formed, are the essential mechanism by which tsf mutations affect tailspike folding . A rational design of su mutants, on the other hand, appears to be more difficult . The exchange of two residues in the active site expected to lead to a drastic release of steric strain neither enhanced the folding properties nor the stability of tailspike . Apparently, side-chain interactions in these cases overcompensate for backbone strain, illustrating the extreme optimization of the tailspike protein for conformational stability . The result exemplifies the view arising from the statistical analysis of the distribution of backbone dihedral angles in known three-dimensional protein structures that the adoption of straight phi/psi angles other than the most favorable ones is often caused by side-chain interactions . Proteins 2000;39:89-101 .

Int J Infect Dis, 2000, 4(2), 96 - 9
Surveillance of bacterial pathogens associated with acute diarrhea in Lima, Peru; Seas C et al.; OBJECTIVES: A study was conducted in Lima, Peru, from January to April 1995, to determine the bacterial pathogens associated with acute diarrhea in adults, their susceptibility to common antimicrobials, the risk factors involved in cholera transmission, and the best clinical predictors of cholera . METHODS: A random sample of adult patients with acute diarrhea was studied . Epidemiologic and clinical data and risk factors to acquire diarrheal diseases were evaluated . Identification of bacteria and susceptibility to antimicrobials were determined . RESULTS: The study included 336 patients . Vibrio cholerae O1 (52.7%), Shigella spp . (4 . 8%), and Salmonella spp (2.7%) were the pathogens most commonly isolated . No resistance to antimicrobials was observed . Patients with cholera had less access to municipal water (P = 0.0018) and were less likely to have homes connected to a sewage system (P = 0 . 0003) or to have indoor toilet facilities (P = 0.0001) than those without cholera . Liquid stools (odds ratio {OR} = 16.51; confidence interval {CI} = 13.71-19.02; P = 0.003), severe dehydration (OR = 2 . 48; CI = 1.57-3.38; P = 0.0083), generalized cramps (OR = 4.63; CI = 3.10-6.17, P < 0.0001), and washerwoman's hands (OR = 2.45; CI = 1 . 55-3.34; P = 0.017) were the best clinical predictors of cholera in this setting . CONCLUSIONS: Cholera is still prevalent in Lima, and people living in environments with low sanitary conditions are especially at risk . Clinical signs of severe dehydration and liquid stools were the best predictors of cholera.

J Nutr Sci Vitaminol (Tokyo), 1999 Dec, 45(6), 785 - 90
Antibacterial activity of garlic powder against Escherichia coli O-157; Sasaki J et al.; The antibacterial activity of garlic powder against O-157 was tested by using garlic bulbs post-harvested 1 y . O-157 at 10(6-7) cfu/mL perished after incubation for 24 h with a 1% solution of garlic powder . The use of powder from fresh garlic was more effective for antibacterial activity than that from old garlic; the 1% solution of fresh garlic powder eradicating the O-157 in 6 h . The antibacterial activity was resistant to heat treatment of 100 degrees C for 20 min . The water-soluble components of garlic powder were fractionated into three fractions (Fr . 1-3) by Sephadex G-100 column chromatography, among which Fr . 3 showed antibacterial activity against O-157 but the other fractions were scarce in activity . The antibacterial activity was also shown against other types of pathogenic bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enteritidis, and Candida albicans . Thus, the practical use of garlic powder is expected to prevent bacteria-caused food poisoning.

Minerva Chir, 1999 Dec, 54(12), 851 - 4
{Perforation of the small intestine}; Buzio M et al.; BACKGROUND: Small bowel perforation is a major problem in abdominal typhi disease, but is seldom observed in Italy, as Salmonella typhi infections are rare in this Nation . The cause of perforation varies greatly . The reported mortality is high and varies from 23 up to 42% . A retrospective study has been performed in order to find how to improve the outcome . METHODS: A series spanning 10 years is reviewed, from January 1, 1987 to December 31, 1997, comprising 60 patients with small bowel perforation, operated in a urgency setting in the Operating Room of the Emergency Department of the Molinette Hospital in Torino . Resection and primary anastomosis were utilized in 33 patients, 27 underwent oversewing . In 3 patients a colostomy was felt necessary because of a concomitant damage of the colon . RESULTS: No leakages occurred . Hospital stay varies from 1 day to 76 days (24 days mean) . Mortality is consistent with literature: 20 patients (33%) but the cause is related to the primary diseases of the patients . Delay in diagnosis did not affect the patient's outcome . CONCLUSIONS: In conclusion, it is confirmed the one-time surgery as the choice treatment in small bowel perforations from causes other then S . typhi infection . Mortality is not directly related to the consequences of surgical repair.

J Bacteriol, 2000 Apr, 182(8), 2341 - 4
Identification of SopE2, a Salmonella secreted protein which is highly homologous to SopE and involved in bacterial invasion of epithelial cells; Bakshi CS et al.; Type III secreted Sop protein effectors are delivered into target eukaryotic cells and elicit cellular responses underlying Salmonella pathogenicity . In this work, we have identified another secreted protein, SopE2, and showed that SopE2 is an important invasion-associated effector . SopE2 is encoded by the sopE2 gene which is present and conserved in pathogenic strains of Salmonella . SopE2 is highly homologous to SopE, a protein encoded by a gene within a temperate bacteriophage and present in only some pathogenic strains.

J Bacteriol, 2000 Apr, 182(8), 2262 - 8
Complex function for SicA, a Salmonella enterica serovar typhimurium type III secretion-associated chaperone; Tucker SC et al.; Salmonella enterica encodes a type III secretion system within a pathogenicity island located at centisome 63 that is essential for virulence . All type III secretion systems require the function of a family of low-molecular-weight proteins that aid the secretion process by acting as partitioning factors and/or secretion pilots . One such protein is SicA, which is encoded immediately upstream of the type III secreted proteins SipB and SipC . We found that the absence of SicA results in the degradation of both SipB and SipC . Interestingly, in the absence of SipC, SipB was not only stable but also secreted at wild-type levels in a sicA mutant background, indicating that SicA is not required for SipB secretion . We also found that SicA is capable of binding both SipB and SipC . These results are consistent with a SicA role as a partitioning factor for SipB and SipC, thereby preventing their premature association and degradation . We also found that introduction of a sicA null mutation results in the lack of expression of SopE, another type III-secreted protein . Such an effect was shown to be transcriptional . Introduction of a loss-of-function sipC mutation into the sicA mutant background rescued sopE expression . These results indicate that the effect of sicA on sopE expression is indirect and most likely exerted through a regulatory factor(s) partitioned by SicA from SipC . These studies therefore describe a surprisingly complex function for the Salmonella enterica type III secretion-associated chaperone SicA.

J Bacteriol, 2000 Apr, 182(8), 2245 - 52
OmpR regulates the stationary-phase acid tolerance response of Salmonella enterica serovar typhimurium; Bang IS et al.; Tolerance to acidic environments is an important property of free-living and pathogenic enteric bacteria . Salmonella enterica serovar Typhimurium possesses two general forms of inducible acid tolerance . One is evident in exponentially growing cells exposed to a sudden acid shock . The other is induced when stationary-phase cells are subjected to a similar shock . These log-phase and stationary-phase acid tolerance responses (ATRs) are distinct in that genes identified as participating in log-phase ATR have little to no effect on the stationary-phase ATR (I . S . Lee, J . L . Slouczewski, and J . W . Foster, J . Bacteriol . 176:1422-1426, 1994) . An insertion mutagenesis strategy designed to reveal genes associated with acid-inducible stationary-phase acid tolerance (stationary-phase ATR) yielded two insertions in the response regulator gene ompR . The ompR mutants were defective in stationary-phase ATR but not log-phase ATR . EnvZ, the known cognate sensor kinase, and the porin genes known to be controlled by OmpR, ompC and ompF, were not required for stationary-phase ATR . However, the alternate phosphodonor acetyl phosphate appears to play a crucial role in OmpR-mediated stationary-phase ATR and in the OmpR-dependent acid induction of ompC . This conclusion was based on finding that a mutant form of OmpR, which is active even though it cannot be phosphorylated, was able to suppress the acid-sensitive phenotype of an ack pta mutant lacking acetyl phosphate . The data also revealed that acid shock increases the level of ompR message and protein in stationary-phase cells . Thus, it appears that acid shock induces the production of OmpR, which in its phosphorylated state can trigger expression of genes needed for acid-induced stationary-phase acid tolerance.

Poult Sci, 2000 Mar, 79(3), 331 - 5
Comparison of the effects of dietary selenium, zinc, and selenium and zinc supplementation on growth and immune response between chick groups that were inoculated with Salmonella and aflatoxin or Salmonella; Hegazy SM et al.; The effects of four diets (basal diet, Se, Zn, and Se- and Zn-enriched diets) fed to chicks that were administered one of three treatments {Salmonella and aflatoxin inoculation (T1), Salmonella inoculation (T2), or uninoculated (T3)} were investigated for growth and immune responses . We found a significant improvement in growth performance represented by relative body gain (RBG) and feed efficiency (FE), for the Zn- and Se + Zn-enriched diets fed to the T1 and T2 groups . The antibody immune response was significantly improved for the Se enrichment diet in the T1 and T2 groups . The weight of the bursa and thymus, which relate to the level of the immune response, showed significant decreases, whereas the spleen had a significantly increased relative weight (RW) in the T1 group . The variable dietary trace elements supplement increased the thymic RW in the T2 group.

East Afr Med J, 1999 Nov, 76(11), 623 - 5
Antibody levels to Salmonella typhi and paratyphi in Nigerians; Tanyigna KB et al.; OBJECTIVE: To determine the antibody titre levels to typhoid/paratyphoid fever organisms among apparently healthy volunteers . DESIGN: Cross sectional study . SETTING: General community and University Teaching Hospital . PARTICIPANTS: Volunteer sample of 323 apparently healthy individuals with body temperatures < or = 37.8 degrees C . MAIN OUTCOME MEASURES: Questionnaire administration to classify volunteers into three socio-economic status (SES) . RESULTS: There were 35.29% of the apparently healthy population in Jos community with antibodies to typhoid/paratyphoid fever organisms . The presence of these antibodies were neither sex nor SES related . Normal antibody titres were up to 1:40 and 1:80 for O and H Salmonella antigens respectively . Contrary to the general belief, typhoid/paratyphoid fevers have not affected virtually everybody in Nigeria . The difference between those without previous history and those with previous history was significant (p < 0.05) with those in the former category having a higher percentage . CONCLUSION: For a single sero-diagnosis to have any diagnostic value in Jos community and its environs, only a four-fold rise to what has been found to be normal should be significant . This means that only titres of 1:160 and 1:320 and above for O and H antigens should be considered significant.

Theriogenology, 1999 Jul 15, 52(2), 247 - 57
Risk factors for Neospora caninum-associated abortion storms in dairy herds in The Netherlands (1995 to 1997); Bartels CJ et al.; A 2 to 1 matched case control study design was used to analyze herd level risk factors for Neospora caninum-associated abortion storms in 47 dairy herds . Data were obtained using a questionnaire regarding the state of affairs at the farms over the 2 years prior to the abortion storm . The questionnaire included 120 variables considered to be potential risk factors for either introduction of infection or recrudescence of chronic infection . The relationship between risk factors and case control pairs was analyzed by conditional logistic regression using a three-steps procedure . In addition, cross sectional serology was used to assess the possible role of concomitant infections . The main factors that were significant in the analysis and that were considered to have potential biological relevance were the presence of dogs, the presence of poultry, and the feeding of moldy maize-silage during summer . For both the presence of dogs and the presence of poultry on the farms, a linear relationship was found between the number of animals and the assessed risk for an abortion storm . These findings suggest a possible role of these species in the transmission of N . caninum . Further evidence for such a role of dogs was the significant association between the presence of dogs and the presence of seropositive cattle in the control herds . The feeding of moldy fodder is considered to be a factor which may induce recrudescence of a latent N . caninum-infection by mycotoxins causing immune suppression . We also found some evidence for a possible influence of management practices around calving and a high prevalence of retained afterbirths . No significant association was found for herd level prevalence of antibodies to bovine viral diarrhea virus, bovine herpesvirus 1, Leptospira hardjo or Salmonella dublin.

Int J Food Microbiol, 1999 Nov 15, 52(3), 123 - 53
Microbiological safety evaluations and recommendations on sprouted seeds . National Advisory Committee on Microbiological Criteria for Foods; A case of acute pancreatitis complicating Salmonella enteritis; Second Department of Internal Medicine, Kobe University School of Medicine, JapanWe report a case of acute pancreatitis complicating Salmonella enteritis . A 43-yr-old woman who was admitted to our department because of Salmonella enteritis developed clinical acute pancreatitis with laboratory and radiographic signs on the fourth hospital day . She was free from symptoms on the eighth hospital day, but her elevated serum amylase and lipase levels persisted for more than 2 m.o . In this case, clinical acute pancreatitis was a complication of bacterial enteritis caused by Salmonella enteritidis, and it was characterized by onset a few days after the onset of enteritis and by sustained elevation of serum pancreatic enzyme levels.

Vet Microbiol, 2000 Apr 4, 73(1), 61 - 73
A critical assessment of antimicrobial treatment in uncomplicated Salmonella enteritis; van Duijkeren E et al.; The human and veterinary literature on the effect of antimicrobials on the clinical and bacteriological cure in uncomplicated Salmonella gastroenteritis is reviewed . Comparison of data on the efficacy of conventional antimicrobials (chloramphenicol, neomycin, ampicillin, amoxycillin, tetracycline, trimethoprim/sulfonamide combinations) and the newer fluoroquinolones indicate that quinolones may shorten the course of clinical disease in contrast to the conventional antimicrobials . Postconvalescent excretion of Salmonella was not affected by the conventional antimicrobials whereas the data on the fluoroquinolones in this respect are conflicting . The fluoroquinolones are the drugs of choice in human medicine for severe Salmonella infections and for the elimination of the carrier state . These drugs have not been evaluated in this respect in veterinary medicine . Well designed prospective placebo-controlled studies regarding the effect of antimicrobials, especially the fluoroquinolones, on the clinical cure and the postconvalescent shedding of Salmonella in animals are imperative to develop optimal therapeutic strategies.

J Physiol Biochem, 1999 Dec, 55(4), 301 - 8
High hemoglobin affinity to oxygen and its relationships with lipid peroxidation during fever; Zinchuk V; The effects of high hemoglobin-oxygen affinity (HOA) on rectal temperature and lipid free radical oxidation were investigated in red blood cells, heart, liver and kidneys of male rats during fever . Fever was induced by intraperitoneal injection of Salmonella typhi lipopolysaccharide (LPS; 5.0 mg kg(-1)) . HOA was increased by addition of 0.5% sodium cyanate to drinking water for eight weeks . HOA modification (actual half-saturation oxygen pressure, P50act, decreased to 23.3+/-0.7 vs . 31.6+/-0.7 Torr in control; p < 0.001) weakened a febrile response: rise of temperature after 4 hours was 0.79+/-0.2 degrees C vs . 1.38+/-0.1 degrees C in rats with normal HOA (p < 0.05) . In red cells and tissues of rats with normal HOA, concentrations of conjugated dienes and Schiff bases increased during fever, and alpha-tocopherol level and catalase activity decreased . Rats with increased HOA had an inverse pattern of such changes . Changes in rectal temperature and markers of free radical oxidation correlated with a shift of oxyhemoglobin dissociation curve leftwards . The present results indicate that the intentional increment of HOA may substantially diminish lipid peroxidation activity, increase the body antioxidant content during fever and decrease the febrile response on LPS.

Biol Neonate, 2000 Mar, 77(3), 191 - 5
Prophylactic treatment of endotoxic shock with monophosphoryl lipid A in newborn rats; Wy CA et al.; Mortality due to gram-negative septic shock remains high despite advances in medical care . Induction of endotoxin tolerance might be a new treatment strategy to prevent septic shock in the newborn . The present study was performed to show that an injection in pregnant rats of monophosphoryl lipid A (MPL), a nontoxic derivative of lipopolysaccharide (LPS), induces tolerance to Salmonella enteritidis LPS and tumor necrosis factor alpha (TNF-alpha) in their offspring . MPL at a dose of 2 mg/kg was injected into pregnant rats on the 19th day of gestation . Their 0-day-old offspring later received an intraperitoneal injection of S . enteritidis LPS or TNF-alpha . Newborn rats of MPL-treated dams exhibited a higher survival rate, absence of lactacidemia and lower plasma TNF-alpha concentration in response to S . enteritidis LPS when compared to the newborn rats of saline-treated dams . Newborn rats of MPL-treated dams were more tolerant to TNF-alpha than those of saline-treated dams . MPL injection into pregnant rats did not increase plasma endotoxin concentration in the fetuses, suggesting no placental passage took place, but it did increase plasma TNF-alpha concentration . We concluded that an injection of MPL into pregnant rats induced tolerance to LPS in their offspring, which might be due to TNF-alpha-induced TNF-alpha tolerance .

Biol Neonate, 2000 Mar, 77(3), 174 - 80
The effect of cold stimulation to the face on the metabolic rate of the febrile piglet; Voss LJ et al.; Sudden infant death syndrome has been associated with winter climates, infection, and overwrapping of babies . The hypothesis has been tested in this laboratory that two different causes of increased metabolic rate, high core temperature (via the van't Hoff or 'Q10' effect) and face-cooling, might synergistically induce hyperthermia . This proved not to be the case . We now report on a 'febrile' state adding Salmonella abortus equi pyrogens . The combination of face-cooling and pyrogen administration to 14 already hot piglets produced an increase in oxygen consumption of 47% in 6 of the animals (19% overall) . Face-cooling alone caused a 6.5% fall in oxygen consumption, and injection of pyrogens alone had no effect on oxygen consumption . We conclude that there may be a danger of life-threatening hyperthermia in the combination of a cold face and febrile state .

J Med Assoc Thai, 1999 Nov, 82 Suppl 1, S144 - 8
Pulmonary involvement in childhood systemic lupus erythematosus; Chantarojanasiri T et al.; Twenty-four children (aged 6-15 years, M:F = 1:11) with systemic lupus erythematosus (SLE), who had respiratory symptoms, were retrospectively reviewed . Chest radiographs obtained from all patients revealed pleural effusion in 13, alveolar infiltration in 9, pericardial effusion and cardiomegaly in 6, interstitial infiltration in 4, hilar adenopathy in 3, lung abscess in 2 and pneumatocele with pneumothorax in 1 . Etiologic organisms were identified in 7 cases; (3 cases of nocardia isolated from pleural effusion and sputum, 2 cases of tuberculosis, 1 case with staphylococcus aureus septicemia and 1 case with salmonella septicemia) . All except one patient improved with medical treatment . One patient died from pneumonitis . Although pulmonary involvement is increasingly recognized in children with SLE, neither roentgenogram nor clinical findings were specific . The differentiation of pulmonary infiltrates caused by lupus lung disease from pulmonary infection should be carefully evaluated.

Lett Appl Microbiol, 2000 Jan, 30(1), 75 - 9
An RNA transcription-based amplification technique (NASBA) for the detection of viable Salmonella enterica; Simpkins SA et al.; Possession of mRNA is indicative of cell viability . RTPCR is not appropriate for mRNA detection as it cannot unambiguously detect mRNA in a DNA background . The alternative amplification technique, NASBA, avoids the disadvantages of RTPCR . We have devised a method for detection of viable Salmonella enterica . This involves NASBA amplification of mRNA transcribed from the dnaK gene . Amplification of mRNA extracted from viable and heat-killed cells from the same population produced consistent and highly significant (P > 0.01) differences between the respective signals . The signal obtained from viable cells was completely eradicated by RNase treatment, while PCR amplification of treated and untreated samples was unaffected, indicating that NASBA was unaffected by background DNA.

Eur J Biochem, 2000 Apr, 267(7), 2014 - 27
The structure of the linkage between the O-specific polysaccharide and the core region of the lipopolysaccharide from Salmonella enterica serovar Typhimurium revisited; Olsthoorn MM et al.; Salmonella enterica sv . Typhimurium strain 1135 possesses smooth(S)-form lipopolysaccharide (LPS) . Although the structures of the core region and the O-specific polysaccharide were investigated intensively between the 1960s and the 1980s, the structure of the linkage region between the O-chain and the core was not elucidated unequivocally . By using modern MS and high-field NMR spectroscopy for analysis of the isolated carbohydrate backbone of the LPS, it has been shown that it is a beta-D-Galp residue that links the first repeating unit of the O-specific polysaccharide to O-4 of the last D-Glcp residue of the core region . Interestingly, this particular D-Galp residue is alpha-linked in all following repeating units . The data are discussed with regard to the ligation of O-specific polysaccharide and core region during LPS biosynthesis.

FEMS Immunol Med Microbiol, 2000 Apr, 27(4), 357 - 64
Recombinant live Salmonella spp . for human vaccination against heterologous pathogens; Bumann D et al.; Live attenuated Salmonella spp . are promising candidates as oral vaccine delivery systems for heterologous antigens . Clinical trials have demonstrated that this approach is feasible for human vaccinations but further optimisation is necessary to obtain a better efficacy . Here, we discuss how existing clinical and pre-clinical data can be used to guide such optimisation efforts.

FEMS Immunol Med Microbiol, 2000 Apr, 27(4), 275 - 81
Kinetics of the mucosal antibody secreting cell response and evidence of specific lymphocyte migration to the lung after oral immunisation with attenuated S . enterica var . typhimurium; Allen JS et al.; The kinetic of mucosal secretory responses elicited by the vaccine vector Salmonella enterica var . typhimurium (S . typhimurium) was examined by enzyme linked immunospot (ELISPOT) and compared with serum responses . Mice immunised orally with BRD509, the aroA, aroD mutant of virulent S . typhimurium SL1344 expressing the C Fragment of tetanus toxin (TT), simultaneously developed an IgA antibody secreting cells (ASC) response in the gastrointestinal lamina propria, the spleen and the lung, against both S . typhimurium lipopolysaccharide (LPS) and TT . The magnitude of the ASC response was greatest in the gut, was boosted by a secondary immunisation at day 25, and the kinetic of the response did not correlate with the appearance of serum antibodies . This study suggests that S . typhimurium can engage the common mucosal immune system to effect mucosal secretory responses at distal sites, however, the magnitude of the responses is both greatest in the gut and antigen-specific . The ASC origin of the serum antibodies specific for S . typhimurium and antigens expressed by the bacterium is yet to be elucidated.

Prev Vet Med, 2000 Mar 29, 44(1-2), 9 - 20
Risk factors for Salmonella persistence after cleansing and disinfection in French broiler-chicken houses; Rose N et al.; A prospective survey was carried out in 86 broiler houses in western France to identify risk factors for Salmonella persistence in French broiler houses . The Salmonella status of the house after cleansing and disinfection, was assessed from gauze-swab samples taken from the walls, feeders, ventilation system and bedding (analysed with classical bacteriological methods) . Thirty three (38%) houses had at least one contaminated sample and were classified as Salmonella-contaminated houses in the logistic regression . The absence of a terminal disinfection and a disinfection procedure performed by the farm staff rather than a contractor were positively related to the Salmonella contamination of the house after cleansing and disinfection . The risk for Salmonella persistence after decontamination was increased if rodents were observed by the farmer, if a large part of the access area to the house was accessible to trucks, and if a disease leading to a treatment occurred in the previous flock.

Res Microbiol, 2000 Jan-Feb, 151(1), 63 - 5
Supplement 1998 (no . 42) to the Kauffmann-White scheme; Popoff MY et al.; This supplement reports the characterization of 14 new Salmonella serovars recognized in 1998 by the WHO Collaborating Centre for Reference and Research on Salmonella: 11 were assigned to S . enterica subsp . enterica, one to subspecies salamae, one to subspecies diarizonae, and one to subsp . indica . In addition, the antigenic factor H:z88 is described.

Res Microbiol, 2000 Jan-Feb, 151(1), 37 - 42
Sequence variation of the 16S to 23S rRNA spacer region in Salmonella enterica; Christensen H et al.; The possibility for identification of Salmonella enterica serotypes by sequence analysis of the 16S to 23S rRNA internal transcribed spacer was investigated by direct sequencing of polymerase chain reaction-amplified DNA from all operons simultaneously in a collection of 25 strains of 18 different serotypes of S . enterica, and by sequencing individual cloned operons from a single strain . It was only possible to determine the first 117 bases upstream from the 23S rRNA gene by direct sequencing because of variation between the rrn operons . Comparison of sequences from this region allowed separation of only 15 out of the 18 serotypes investigated and was not specific even at the subspecies level of S . enterica . To determine the differences between internal transcribed spacers in more detail, the individual rrn operons of strain JEO 197, serotype IV 43:z4,z23:-, were cloned and sequenced . The strain contained four short internal transcribed spacer fragments of 382-384 bases in length, which were 98.4-99.7% similar to each other and three long fragments of 505 bases with 98.0-99.8% similarity . The study demonstrated a higher degree of interbacterial variation than intrabacterial variation between operons for serotypes of S . enterica.

Infect Immun, 2000 Apr, 68(4), 2135 - 41
Pilot study of phoP/phoQ-deleted Salmonella enterica serovar typhimurium expressing Helicobacter pylori urease in adult volunteers; Angelakopoulos H et al.; Attenuated Salmonella enterica serovar Typhi has been studied as an oral vaccine vector . Despite success with attenuated S . enterica serovar Typhimurium vectors in animals, early clinical trials of S . enterica serovar Typhi expressing heterologous antigens have shown that few subjects have detectable immune responses to vectored antigens . A previous clinical study of phoP/phoQ-deleted S . enterica serovar Typhi expressing Helicobacter pylori urease from a multicopy plasmid showed that none of eight subjects had detectable immune responses to the vectored antigen . In an attempt to further define the variables important for engendering immune responses to vectored antigens in humans, six volunteers were inoculated with 5 x 10(7) to 8 x 10(7) CFU of phoP/phoQ-deleted S . enterica serovar Typhimurium expressing the same antigen . Two of the six volunteers had fever; none had diarrhea, bacteremia, or other serious side effects . The volunteers were more durably colonized than in previous studies of phoP/phoQ-deleted S . enterica serovar Typhi . Five of the six volunteers seroconverted to S . enterica serovar Typhimurium antigens and had strong evidence of anti-Salmonella mucosal immune responses by enzyme-linked immunospot studies . Three of six (three of five who seroconverted to Salmonella) had immune responses in the most sensitive assay of urease-specific immunoglobulin production by blood mononuclear cells in vitro . One of these had a fourfold or greater increase in end-point immunoglobulin titer in serum versus urease . Attenuated S . enterica serovar Typhimurium appears to be more effective than S . enterica serovar Typhi for engendering immune responses to urease . Data suggest that this may be related to a greater stability of antigen-expressing plasmid in S . enterica serovar Typhimurium and/or prolonged intestinal colonization . Specific factors unique to nontyphoidal salmonellae may also be important for stimulation of the gastrointestinal immune system.

Epidemiol Infect, 2000 Feb, 124(1), 17 - 23
The antibiotic resistance patterns of Salmonella Typhi isolates in Italy, 1980-96 . The Italian SALM-NET Working Group . Salmonella Network; Scuderi G et al.; In this paper we report the distribution of Salmonella Typhi isolates in Italy and their resistance patterns to antibiotics . The data were collected by the Italian SALM-NET surveillance system in a pilot retrospective study of the period 1980-96 . Data on drug-resistance were available for 82 isolates out of 176 S . Typhi isolated in Italy . Of these 82 isolates, 32 (39%) were resistant or intermediate to 1 or more antibiotics . Eight isolates were resistant and 7 intermediate to streptomycin; 4 isolates were resistant to ampicillin alone or in association with other antibiotics; only 2 strains (1 isolated in Lombardia in 1993 and the other 1 in Lazio in 1994) were resistant to chloramphenicol, and 2 (isolated in Sardegna and Piemonte in 1995 and 1996, respectively) showed intermediate resistance to chloramphenicol . The strains showing resistance to 3 or more antibiotics were very scarce: 1 (with 5 complete resistances) was isolated in Lazio in 1994, and another 1 (with complete resistance to 10 antibiotics and intermediate resistance to 2 antibiotics) was isolated in Molise in 1988 . In conclusion, besides the routine activities to control typhoid fever, an accurate and continuous surveillance is necessary in order to quickly identify multidrug-resistant (MDR) S . Typhi strains and prevent their spread, even though their level, in our country, is still quite low.

Epidemiol Infect, 2000 Feb, 124(1), 9 - 16
Characterization of multi-drug resistant Salmonella typhi isolated from Pakistan; Shanahan PM et al.; Thirty-nine strains of Salmonella typhi, isolated in 1995 from four Districts in Pakistan, Rawalpindi, Islamabad, Kharian and Jehlem, were catalogued and examined . Chromosomal DNA from each isolate was digested with XbaI restriction endonuclease and subjected to pulsed-field gel electrophoresis . Three clonal variants comprising of 17-19 DNA fragments were identified . Antibiotic susceptibility testing identified that 37 of the S . typhi were resistant to chloramphenicol, trimethoprim and ampicillin . These antibiotic resistance genes were found to be located on one of four plasmids belonging to incompatibility group IncHI1 and ranging in size from 150-175 Kb . The genes responsible for this resistance in each case were the chloramphenicol acetyltransferase (CAT) type I, the dihydrofolate reductase (DHFR) type VII and the beta-lactamase TEM-1 respectively.

Epidemiol Infect, 2000 Feb, 124(1), 1 - 7
A community--wide outbreak of Salmonella enterica serotype Typhimurium infection associated with eating a raw milk soft cheese in France; De Valk H et al.; In 1997, a community-wide outbreak of Salmonella enterica serotype Typhimurium (S . typhimurium) infection occurred in France . The investigation included case searching and a case-control study . A case was defined as a resident of the Jura district with fever or diarrhoea between 12 May and 8 July 1997, from whom S . typhimurium was isolated in stool or blood . One hundred and thirteen cases were identified . Thirty-three (83 %) of 40 cases but only 23 (55 %) of 42 community controls, matched for age and area of residence, reported eating Morbier cheese (Odds ratio: 6.5; 95 % Confidence Interval: 1.4-28.8) . Morbier cheese samples taken from the refrigerators of two case-patients and one symptom-free neighbour cultured positive for S . typhimurium of the same phage type as the human isolates . The analysis of distribution channels incriminated one batch from a single processing plant . These findings show that an unpasteurized soft cheese is an effective vehicle of S . typhimurium transmission.

J Korean Med Sci, 2000 Feb, 15(1), 83 - 7
NRAMP1 gene polymorphisms in patients with rheumatoid arthritis in Koreans; Yang YS et al.; Natural resistance-associated macrophage protein 1 (Nramp1) is a genetic locus associated with innate resistance or susceptibility of murine hosts to infection with intracellular pathogens such as Salmonella, Leishmania and Mycobacterium . The human homologue of the Nramp1 gene, designated NRAMP1, has been investigated as a candidate gene for genetic susceptibility to autoimmune diseases as well as infections . This study tries to determine whether NRAMP1 polymorphisms are associated with susceptibility to rheumatoid arthritis in Koreans . The nine NRAMP1 polymorphisms (1 microsatellite, 1 variation in 3' UTR, 5 silent substitution, 2 amino acid substitution) were typed by PCR-RFLP in 74 patients with rheumatoid arthritis (RA) and 53 healthy controls in Koreans . The distribution of allele and genotype frequencies were compared between patients and controls . Three NRAMP1 polymorphisms (823C/T, D543N and 1729+55del4) were significantly associated with RA . In addition, there were significant differences in the genotype frequencies for 823C/T, D543N and 1729+ 55del4 polymorphisms between RA patients and controls . Genotypes of A/A homozygote for D543N and TGTG deletion homozygote for 1729+55del4 were only detected in the patient group . These data indicate that genetic polymorphisms of NRAMP1 might be associated with the susceptibility to rheumatoid arthritis in Koreans.

Int J Food Sci Nutr, 1999 Nov, 50(6), 451 - 5
Survival of some species of Salmonella and Shigella in mukumbi, a traditional Zimbabwean wine; Mugochi T et al.; Mukumbi is a traditional Zimbabwean wine prepared from a fruit called mapfura by the Shona people of Zimbabwe and amaganu by the Ndebele . The majority of people in Africa call the tree marula (Sclerocarya birrea subspecies caffra) . The survival of Salmonella group B, Salmonella enteritidis, Shigella sonnei and Shigella flexneri in unfermented and fermented mapfura (marula) juice (mukumbi) was investigated . It was found that within 30 min of inoculation, there were no longer any viable pathogens in the fermented mapfura juice whilst in the unfermented juice, more than 10(4) cfu/ml were still viable after 8 h . When lactic acid (0.25 mg/ml) was added to the unfermented mapfura juice, more than 10(4) cfu/ml were also still viable after 8 h but none were viable after 24 h . The fermented product, mukumbi, has a rapid antimicrobial effect against the pathogens as compared to the unfermented juice and is therefore safe from contamination with these pathogens . It appears thus that the death of the pathogens was due to other compounds besides the low levels of lactic acid.

J Biomater Sci Polym Ed, 2000, 11(2), 187 - 96
In vitro toxicity of spiroorthocarbonate monomers designed for non-shrinking dental restoratives; Kostoryz EL et al.; In development of photopolymerized expanding monomers with epoxy resin systems, there is a need for reactive expanding monomers that exert a good biocompatibility profile . The objective of this study was to evaluate the in vitro toxicology of new spiroorthocarbonates designed to be expanding monomers . The expanding monomers investigated were: trans/trans-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro{5,5} undecane (DTM-TOSU), 5,5-diethyl-19-oxadispiro-{1,3-dioxane-2,2'-1,3-dioxane-5',4'-bicy clo{4.1.0}heptane} (DECHE-TOSU); 3,9-diethyl-3,9-dipropionyloxy methyl-1,5,7,11-tetraoxaspiro{5.5}undecane (DEDPM-TOSU); and 3,9-diethyl-3,9-diacetoxy methyl-1,5,7,11-tetraoxaspiro{5.5}undecane (DAMDE-TOSU) . The in vitro toxicology of these monomers measured their cytotoxicity and mutagenicity potential . Succinic dehydrogenase (SDH) activity in the MTT assay was used to assess the toxic dose that kills 50% of cells (TC50) for all the monomers . Their mutagenic potential was measured in the Ames Salmonella assay with and without metabolic activation . Two solvents, DMSO and acetone, were used to validate effects . Appropriate controls included the solvents alone . All the expanding monomers in this study were less cytotoxic than BISGMA (p < 0.01), a commercial component of dental restoratives . The relative cytotoxicity of the expanding monomers in DMSO was defined in the following order: DTM-TOSU (more toxic) > DECHE-TOSU > DEDPM-TOSU > DAMDE-TOSU . Each was significantly different from the other (p < 0.05) . Overall, the TC50 values of all expanding monomers were significantly greater in DMSO than in acetone (p < 0.05) . However, for BISGMA this trend was opposite . For mutagenicity results, the expanding monomers were non-mutagenic and there was no solvent effect on this outcome . The non-mutagenicity and low cytotoxicity profile of these expanding monomers suggests their potential for development of biocompatible non-shrinking composites.

Vaccine, 2000 Apr 28, 18(21), 2239 - 43
Granulocyte selected live Salmonella enteritidis vaccine is species specific; Kramer T et al.; Selection of Salmonellae from granulocytes may result in safe and effective vaccine strains . We demonstrated that the reduced virulence of such strains is limited to the species in which the selection was made . Repeated (sequential) selection of Salmonella enteritidis from chicken granulocytes yielded an avirulent strain for chickens . Repeated (sequential) selection of Salmonella enteritidis from pig granulocytes (neutrophils) yielded a strain that was comparable to the original wildtype strain.

Ann Trop Med Parasitol, 1999 Oct, 93(7), 669 - 78
The host response in malaria and depression of defence against tuberculosis; Enwere GC et al.; Malaria causes significant morbidity and mortality world-wide . Both asymptomatic and symptomatic malarial infections cause immune depression, which predisposes the host to infection with other microorganisms . Specific clinical investigations have shown, for example, that those with malaria-attributable anaemia are particularly likely to have Salmonella septicaemia, and that asymptomatic malarial infection causes diminished response to polysaccharide vaccine . The results of clinical studies and experiments with animal models have revealed that malarial parasites can decrease their vertebrate host's effective humoral and cellular immune responses . In this review, the possible ways in which this malaria-induced immune impairment could affect the host's response to Mycobacterium tuberculosis infection are considered . Could malarial infection be one of the reasons for the persistence of tuberculosis in malaria-endemic regions?

J Bacteriol, 2000 Apr, 182(7), 2026 - 32
Isolation and characterization of vicH, encoding a new pleiotropic regulator in Vibrio cholerae; Tendeng C et al.; During the last decade, the hns gene and its product, the H-NS protein, have been extensively studied in Escherichia coli . H-NS-like proteins seem to be widespread in gram-negative bacteria . However, unlike in E . coli and in Salmonella enterica serovar Typhimurium, little is known about their role in the physiology of those organisms . In this report, we describe the isolation of vicH, an hns-like gene in Vibrio cholerae, the etiological agent of cholera . This gene was isolated from a V . cholerae genomic library by complementation of different phenotypes associated with an hns mutation in E . coli . It encodes a 135-amino-acid protein showing approximately 50% identity with both H-NS and StpA in E . coli . Despite a low amino acid conservation in the N-terminal part, VicH is able to cross-react with anti-H-NS antibodies and to form oligomers in vitro . The vicH gene is expressed as a single gene from two promoters in tandem and is induced by cold shock . A V . cholerae wild-type strain expressing a vicHDelta92 gene lacking its 3' end shows pleiotropic alterations with regard to mucoidy and salicin metabolism . Moreover, this strain is unable to swarm on semisolid medium . Similarly, overexpression of the vicH wild-type gene results in an alteration of swarming behavior . This suggests that VicH could be involved in the virulence process in V . cholerae, in particular by affecting flagellum biosynthesis.

J Bacteriol, 2000 Apr, 182(7), 1923 - 9
Distribution of intervening sequences in the genes for 23S rRNA and rRNA fragmentation among strains of the Salmonella reference collection B (SARB) and SARC sets; Pabbaraju K et al.; Intervening sequences (IVSs) occur sporadically in several bacterial genera in the genes for 23S rRNA at relatively conserved locations . They are cleaved after transcription and lead to the presence of fragmented rRNA, which is incorporated into the ribosomes without religation but is nevertheless functional . The fragmentation of rRNA and the number of IVSs in all 72 strains of the Salmonella Reference Collection B set and 16 strains of the Salmonella Reference Collection C set, which have been established on the basis of multilocus enzyme electrophoresis (MLEE), were analyzed in the present study . Fragmentation of 23S rRNA was restricted to conserved cleavage sites located at bp 550 (helix 25) and bp 1170 (helix 45), locations where IVSs have been reported . Random cleavage at sites where IVSs could not be detected was not seen . Uncleaved IVSs were not detected in any case; thus, the IVSs invariably led to rRNA fragmentation, indicating a strong selection for maintenance of RNase III cleavage sites . The distribution of the number of IVSs carried by the different strains in the seven rrl genes is diverse, and the pattern of IVS possession could not be related to the MLEE pattern among the various Salmonella strains tested; this indicates that the IVSs are frequently exchanged between strains by lateral transfer . All eight subspecies of the genus Salmonella, including subspecies V represented by Salmonella bongori, have IVSs in both helix 25 and helix 45; this indicates that IVSs entered the genus after its divergence from Escherichia coli (more than 100 million years ago) but before separation of the genus Salmonella into many forms or that they were in the ancestor but have been lost from Escherichia.

J Bacteriol, 2000 Apr, 182(7), 1872 - 82
Multiple factors independently regulate hilA and invasion gene expression in Salmonella enterica serovar typhimurium; Lucas RL et al.; HilA activates the expression of Salmonella enterica serovar Typhimurium invasion genes . To learn more about regulation of hilA, we isolated Tn5 mutants exhibiting reduced hilA and/or invasion gene expression . In addition to expected mutations, we identified Tn5 insertions in pstS, fadD, flhD, flhC, and fliA . Analysis of the pstS mutant indicates that hilA and invasion genes are repressed by the response regulator PhoB in the absence of the Pst high-affinity inorganic phosphate uptake system . This system is required for negative control of the PhoR-PhoB two-component regulatory system, suggesting that hilA expression may be repressed by PhoR-PhoB under low extracellular inorganic phosphate conditions . FadD is required for uptake and degradation of long-chain fatty acids, and our analysis of the fadD mutant indicates that hilA is regulated by a FadD-dependent, FadR-independent mechanism . Thus, fatty acid derivatives may act as intracellular signals to regulate hilA expression . flhDC and fliA encode transcription factors required for flagellum production, motility, and chemotaxis . Complementation studies with flhC and fliA mutants indicate that FliZ, which is encoded in an operon with fliA, activates expression of hilA, linking regulation of hilA with motility . Finally, epistasis tests showed that PhoB, FadD, FliZ, SirA, and EnvZ act independently to regulate hilA expression and invasion . In summary, our screen has identified several distinct pathways that can modulate S . enterica serovar Typhimurium's ability to express hilA and invade host cells . Integration of signals from these different pathways may help restrict invasion gene expression during infection.

Environ Mol Mutagen, 2000, 35(2), 106 - 13
Mutation spectra of the drinking water mutagen 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF) in Salmonella TA100 and TA104: comparison to MX; Shaughnessy DT et al.; The chlorinated drinking water mutagen 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF) occurs at concentrations similar to or greater than that of the related furanone 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) . MCF and MX differ structurally only by replacement of a 3-methyl in MCF with a 3-dichloromethyl in MX; yet, MCF is significantly less mutagenic than MX and produces different adducts when reacted with nucleosides or DNA . To explore further the effects that these structural differences might have on the biological activity of MCF and MX, we determined the mutation spectra of MCF in Salmonella strains TA100 and TA104 and of MX in strain TA104; the spectrum of MX in TA100 had been determined previously . In TA100, which presents only GC targets for mutagenesis, MCF induced primarily (75%) GC --> TA transversions, with most of the remaining revertants (20%) being GC --> AT transitions . This spectrum was not significantly different from that of MX in TA100 (P = 0.07) . In TA104, which presents both GC and AT targets, MCF induced a lower percentage (57%) of GC --> TA transversions, with most of the remaining revertants (33%) being AT --> TA transversions . In contrast, MX induced almost only (98%) GC --> TA transversions in TA104, with the remaining revertants (2%) being AT --> TA transversions . Thus, almost all (98%) of the MX mutations were targeted at GC sites in TA104, whereas only 63% of the MCF mutations were so targeted . These results are consistent with the published findings that MX: (1) forms an adduct on guanosine when reacted with guanosine, (2) induces apurinic sites in DNA, and (3) forms a minor adduct on adenosine when reacted with adenosine or DNA . The results are also consistent with evidence that MCF forms adenosine adducts when reacted with adenosine . Our results show that the replacement of the 4-methyl in MCF with a 4-dichloromethyl to form MX not only increases dramatically the mutagenic potency but also shifts significantly the mutagenic specificity from almost equal targeting of GC and AT sites by MCF to almost exclusive targeting of GC sites by MX . Environ . Mol . Mutagen . 35:106-113, 2000 Published 2000 Wiley-Liss, Inc.

Mol Microbiol, 2000 Mar, 35(5), 1052 - 64
Interactions among components of the Salmonella flagellar export apparatus and its substrates; Minamino T et al.; We have examined the cytoplasmic components (FliH, FliI and FliJ) of the type III flagellar protein export apparatus, plus the cytoplasmic domains (FlhAC and FlhBC) of two of its six membrane components . FliH, FlhAC and FliJ, when overproduced, caused inhibition of motility of wild-type cells and inhibition of the export of substrates such as the hook protein FlgE . Co-overproduction of FliH and FliI substantially relieved the inhibition caused by FliH, suggesting that it is excess free FliH that is inhibitory and that FliH and FliI form a complex . We purified His-FLAG-tagged versions of: (i) export components FliH, FliI, FliJ, FlhAC and FlhBC; (ii) rod/hook-type export substrates FlgB (rod protein), FlgE (hook protein), FlgD (hook capping protein) and FliE (basal body protein); and (iii) filament-type export substrates FlgK and FlgL (hook-filament junction proteins) and FliC (flagellin) . We tested for protein-protein interactions by affinity blotting . In many cases, a given protein interacted with more than one other component, indicating that there are likely to be multiple dynamic interactions or interactions that involve more than two components . Interactions of FlhBC with rod/hook-type substrates were strong, whereas those with filament-type substrates were very weak; this may reflect the role of FlhB in substrate specificity switching . We propose a model for the flagellar export apparatus in which FlhA and FlhB and the other four integral membrane proteins of the apparatus form a complex at the base of the flagellar motor . A soluble complex of at least three proteins (FliH, FliI and FliJ) bind the protein to be exported and then interact with the complex at the motor to deliver the protein, which is then exported in an ATP-dependent process mediated by FliI.

Mol Biol Evol, 2000 Feb, 17(2), 301 - 8
Solvent accessibility and purifying selection within proteins of Escherichia coli and Salmonella enterica; Bustamante CD et al.; The neutral theory of molecular evolution predicts that variation within species is inversely related to the strength of purifying selection, but the strength of purifying selection itself must be related to physical constraints imposed by protein folding and function . In this paper, we analyzed five enzymes for which polymorphic sequence variation within Escherichia coli and/or Salmonella enterica was available, along with a protein structure . Single and multivariate logistic regression models are presented that evaluate amino acid size, physicochemical properties, solvent accessibility, and secondary structure as predictors of polymorphism . A model that contains a positive coefficient of association between polymorphism and solvent accessibility and separate intercepts for each secondary-structure element is sufficient to explain the observed variation in polymorphism between sites . The model predicts an increase in the probability of amino acid polymorphism with increasing solvent accessibility for each protein regardless of physicochemical properties, secondary-structure element, or size of the amino acid . This result, when compared with the distribution of synonymous polymorphism, which shows no association with solvent accessibility, suggests a strong decrease in purifying selection with increasing solvent accessibility.

Am J Gastroenterol, 2000 Mar, 95(3), 784 - 7
Typhoid carriers among patients with gallstones are at increased risk for carcinoma of the gallbladder; Dutta U et al.; OBJECTIVE: The aim of this study was to identify risk factors for carcinoma of the gallbladder (CaGB) among patients with gallstones (GS) with special reference to role of chronic Salmonella typhi carrier state . METHODS: A prospective case-control study was conducted in a tertiary care center in India . Cases were defined as consecutive patients with CaGB and GS, whereas controls were patients with GS alone . All were assessed clinically and their demographic data, diet, and smoking history recorded . Patients were detected to be typhoid carriers on the basis of Vi serology by enzyme linked immunosorbent assay . Cases (n = 37) and controls (n = 80) were compared by univariate and logistic regression analysis . RESULTS: The mean age of the cases and the controls were 53.4 +/- 11 yr and 43.5 +/- 14 yr, respectively . Among the cases, six (16%) patients were detected to be typhoid carriers, in contrast to two (2.5%) among controls (p = 0.01) . Compared to controls, cases were more often older (p = 0.0002), of a lower socioeconomic status (p = 0.0005), and smokers (p = 0.0002) . Stepwise logistic regression analysis identified typhoid carrier state (OR = 14; CI 2-92), age > or =47 yr (OR = 5; CI 2-14) and smoking (OR = 11; CI 2-71) as the three independent risk factors for development of CaGB among patients with GS . CONCLUSION: Chronic typhoid carrier state was the most important risk factor among patients with CaGB and gallstones.

Vestn Ross Akad Med Nauk, 1999, (12), 32 - 4
{Temperature-dependent changes in immunochemical properties of lipopolysaccharides of yersinia pestis}; Gremiakova TA et al.; The preparations of pilopolysaccharides (LPS) of virulent and avirulent Y . pestis strains, which have a different composition, were cultivated at different temperatures . Despite the cultivation temperature of parental cells, all LPS preparation inhibited the passive hemagglutination reaction (PHR) of the red blood cells sensitized by LPS isolated from the cultures grown at 26 degrees C by using homologous antisera . In contrast, the homologous system consisting of the red blood cells sensitized by LPS from the EV NIIEG, cultured at 37 degrees C, and the antiserum to these cells proved to be more specific and it was inhibited only by the homologous LPS isolated from the strain EV NIIEG . The similar reaction of the interaction of the red blood cells sensitized by high temperature LPS agents from plasmid-free strains with the same serum was inhibited by all plague LPS preparations . The LPS preparations from the strains Y . pestis 1146 and Y . pseudotuberculosis 9532 obtained when cultivated at 37 degrees C . RHR of the red blood cells sensitized by these preparations was inhibited by homologous LPS irrespective of the temperature of cell cultivation . In all cases, the reaction was specific for Yersinia strains and it was inhibited by LPS from Ra-Rd2 cultures, variants of Salmonella and E . coli.

Mutat Res, 2000 Feb 16, 465(1-2), 201 - 29
Modeling the mouse lymphoma forward mutational assay: the Gene-Tox program database; Grant SG et al.; An SAR model of the induction of mutations at the tk(+/-) locus of L5178Y mouse lymphoma cells (MLA, for mouse lymphoma assay) was derived based upon a re-evaluation of experimental results reported by a Gene-Tox (GT) working group {A.D . Mitchell, A.E . Auletta, D . Clive, P.E . Kirby, M.M . Moore, B.C . Myhr, The L5178Y/tk(+/-) mouse lymphoma specific gene and chromosomal mutation assay . A phase III report of the U.S . Environmental Protection Agency Gene-Tox Program, Mutation Res . 394 (1997) 177-303.} . The predictive performance of the GT MLA SAR model was similar to that of a Salmonella mutagenicity model containing the same number of chemicals . However, the structural determinants (biophores) derived from the GT MLA SAR model include both electrophilic as well as non-electrophilic moieties, suggesting that the induction of mutations in the MLA may occur by both direct interaction with DNA and by non-DNA-related mechanisms . This was confirmed by the observation that the set of biophores associated with MLA overlapped significantly with those associated with phenomena related to loss of heterozygosity, chromosomal rearrangements and aneuploidy . The MLA SAR model derived from the GT data evaluation was significantly more predictive than an SAR model previously derived from MLA data reported by the US National Toxicology Program {B . Henry, S.G . Grant, G . Klopman, H.S . Rosenkranz, Induction of forward mutations at the thymidine kinase locus of mouse lymphoma cells: evidence for electrophilic and non-electrophilic mechanisms, Mutation Res . 397 (1998) 331-335.} . Moreover, the latter model appeared to be more complex than the former, suggesting that the GT induction data was both simpler mechanistically and more homogeneous than that of the NTP.

Mutat Res, 2000 Feb 16, 465(1-2), 191 - 200
Comparison of environmental tobacco smoke concentrations and mutagenicity for several indoor environments; Zhou R et al.; Environmental tobacco smoke (ETS) is a major source for indoor air pollution . Although ETS-caused indoor air pollution has been well studied in the developed countries, few studies have examined ETS indoor air pollution in China, which currently has the largest population of tobacco smokers . In this study, respirable-particulate (RP) from ETS-contaminated (RP-ETS) indoor air was collected and measured in 5 different indoor environments during the winter in the northwestern Liaoning Province, China . The extractable portion of RP-ETS (ERP-ETS) was obtained by dichloromethane extraction and used in the Salmonella mutagenicity assay in the presence of S9 using strains TA98, TA100, and TA1538 . The percentage of RP-ETS attributable to ETS (ETS-RP) and the percentage of ERP-ETS attributable to ETS (ETS-ERP) were estimated by measuring the concentration of solanesol, an ETS marker . Comparative results in 5 different indoor environments were: (1) the concentration of RP-ETS ranged from 197.3 to 1227.6 microg/m(3) and approximately 64.7 to 92 . 0% of the RP-ETS originated from ETS; (2) the concentration of ERP-ETS ranged 88.8 to 601.5 microg/m(3) and approximately 83.1 to 95.4% of the ERP-ETS originated from ETS; (3) the mutagenic potency (revertants/m(3)) of ERP-ETS ranged from 60.4 to 595.5 for TA98, from 33.7 to 312.8 for TA100, and from 49.7 to 475.2 for TA1538 . The data indicate that the extent of ETS pollution and the potential health hazards of ETS to humans in the five indoor environments are in the following increasing order: rural bedrooms, urban living rooms, office rooms, restaurants, and passenger cars in that area.

Int J Immunopharmacol, 2000 May, 22(5), 355 - 64
Effect of Salmonella typhi wild type and O-antigen mutants on human natural killer cell activity; Puente J et al.; We investigated the effect of glutaraldehyde-fixed Salmonella typhi Ty2 (Vi(-)) wild-type (World Health Organization's vaccine strain) and mutant strains MEI028 (rough, O-antigen(-)) and MEI012 {smooth (O-antigen(+)95%), immunomagnetically isolated NK cell preparations . Incubation of PBMC with each and every one of the S . typhi strains studied consistently and significantly, increased this cellular immune function, as well as the supernatant level of the various cytokines tested e.g . IFN-gamma, TNF-alpha, IL-10 and IL-12 (ELISA) . In similar experiments, a significant increase in the cytolytic activity of HPNK cells was elicited by S . typhi Ty2 but not by mutant strain MEI028; neither of the cytokines assayed (IFN-gamma and TNF-alpha) was detected in the supernatant.Our results suggest that S . typhi O-antigen plays an essential role in a mechanism resulting in the direct activation of NK cell activity in HPNK cell preparations . However, the relative quantitative significance of this antigen in the direct stimulation of NK cell cytotoxicity expression in PBMC samples is less clear, as it appears that in this case bacterial-induced monocyte-released cytokines plays a most important role . Incubation with S . typhi Ty2 or MEI028 elicited significant expression of CD69, an early marker of NK cell activation, in PBMC but not in HPNK cell samples (flow cytometry); in similar experiments, the expression of CD16/56 and activation marker CD25 remained essentially unchanged.

J Immunol, 2000 Mar 15, 164(6), 3149 - 56
Salmonella-type heptaacylated lipid A is inactive and acts as an antagonist of lipopolysaccharide action on human line cells; Tanamoto K et al.; The stimulation of both THP-1 and U937 human-derived cells by Salmonella lipid A preparations from various strains, as assessed by TNF-alpha induction and NF-kappaB activation, was found to be very low (almost inactive) compared with Escherichia coli lipid A, but all of the lipid As exerted strong activity on mouse cells and on Limulus gelation activity . Experiments using chemically synthesized E . coli-type hexaacylated lipid A (506) and Salmonella-type heptaacylated lipid A (516) yielded clearer results . Both lipid A preparations strongly induced TNF-alpha release and activated NF-kappaB in mouse peritoneal macrophages and mouse macrophage-like cell line J774-1 and induced Limulus gelation activity, although the activity of the latter was slightly weaker than that of the former . However, 516 was completely inactive on both THP-1 and U937 cells in terms of both induction of TNF-alpha and NF-kappaB activation, whereas 506 displayed strong activity on both cells, the same as natural E . coli LPS . In contrast to the action of the lipid A preparations, all the Salmonella LPSs also exhibited full activity on human cells . However, the polysaccharide portion of the LPS neither exhibited TNF-alpha induction activity on the cells when administered alone or together with lipid A nor inhibited the activity of the LPS . These results suggest that the mechanism of activation by LPS or the recognition of lipid A structure by human and mouse cells may differ . In addition, both 516 and lipid A from Salmonella were found to antagonize the 506 and E . coli LPS action that induced TNF-alpha release and NF-kappaB activation in THP-1 cells.

MMWR Morb Mortal Wkly Rep, 2000 Feb 4, 49(4), 73 - 9
Outbreaks of Salmonella serotype enteritidis infection associated with eating raw or undercooked shell eggs--United States, 1996-1998; Clinical application of a dot blot test for diagnosis of enteric fever due to Salmonella enterica serovar typhi in patients with typhoid fever from Colombia and Peru; Instituto Columbiano de Medicina Tropical, AA 52162 Medellin, Colombia . icmt@epm.net.co

Clinical application of a dot blot test to detect immunoglobulin G (IgG) (88% sensitivity and specificity) and IgM (12.1% sensitivity and 97% specificity) against flagellar antigen from Salmonella enterica serovar Typhi was performed in Peruvian and Colombian patients with typhoid fever . This test can be used as a good predictor of serovar Typhi infection in regions lacking laboratory facilities and in field studies.

Clin Diagn Lab Immunol, 2000 Mar, 7(2), 258 - 64
Improved repetitive-element PCR fingerprinting of Salmonella enterica with the use of extremely elevated annealing temperatures; Johnson JR et al.; Modified thermal cycling conditions were explored in an effort to improve the reproducibility and resolving power of repetitive-element PCR (rep-PCR) fingerprinting . Assay performance was rigorously evaluated under standard and modified cycling conditions, using as a test set 12 strains putatively representing 12 serovars of Salmonella enterica . For all three fingerprint types (ERIC2, BOXA1R, and composite fingerprints), the use of extremely elevated annealing temperatures plus an initial "touchdown" cycling routine yielded significant improvements in day-to-day reproducibility and discriminating power despite the somewhat sparser appearance of the fingerprints . Modified cycling conditions markedly reduced the variability of fingerprints between cyclers, allowing fingerprints from different cyclers to be analyzed together without the degradation of assay performance that occurred with between-cycler analyses under standard cycling conditions . With modified cycling, composite fingerprints exhibited the lowest reproducibility but the highest net discriminating power of the three fingerprint types . rep-PCR fingerprints led to the discovery of a serotyping error involving one of the 12 test strains . These data demonstrate that modified cycling regimens that incorporate elevated annealing temperatures (with or without an initial touchdown routine) may markedly improve the performance of rep-PCR fingerprinting as a bacterial typing tool.

J Neurosurg, 2000 Mar, 92(3), 435 - 41
Induction of tolerance against ischemia/reperfusion injury in the rat brain by preconditioning with the endotoxin analog diphosphoryl lipid A; Toyoda T et al.; OBJECT: Inflammatory responses and oxygen free radicals have increasingly been implicated in the development of ischemic brain injury . In some cases, an attenuation of inflammation or free-radical injury can provide tissue protection . Diphosphoryl lipid A (DPL) is a detoxified derivative of a lipopolysaccharide (endotoxin) of Salmonella minnesota strain R595, which is capable of stimulating the immune system without eliciting direct toxic effects . In this study the authors examined the influence of preconditioning with DPL on ischemia/reperfusion injury in rats . METHODS: Sprague-Dawley rats were injected intravenously with either DPL or vehicle . Twenty-four hours later, some animals were tested for superoxide dismutase (SOD) activity . Others were subjected to a 3-hour period of focal cerebral ischemia and, after a reperfusion period of 24 hours, were killed . Infarction volume, SOD activity, and myeloperoxidase (MPO) activity were assayed in the postischemic animals . Pretreatment with DPL produced significant reductions in cerebral infarction and MPO activity in the ischemic penumbra . A significant enhancement of basal SOD activity was observed 24 hours after DPL treatment (that is, before ischemia), and a further enhancement of SOD activity was seen in the ischemic penumbra 24 hours after reperfusion . CONCLUSIONS: These data provide the first evidence of a neuroprotective effect of preconditioning with DPL in an in vivo model of cerebral ischemia . Although the precise mechanisms through which DPL exerts its neuroprotective influence remain to be established, an inhibition of the complex inflammatory response to ischemia and an enhancement of endogenous antioxidant activity are leading candidates.

Indian J Med Res, 1999 Dec, 110, 183 - 5
Multi-drug resistant non-typhoidal Salmonella spp . associated with acute diarrhoeal disease; Niyogi SK et al.; The prevalence of different serotypes of non-typhoidal Salmonella spp . among patients suffering from acute diarrhoea admitted to the Infectious Diseases Hospital, Calcutta was investigated . The predominant serogroup was C and Salmonella infantis was the major serotype isolated followed by S . worthington, S . enteritidis, S . typhimurium, S . weltevereden and S . newport . All the Salmonella strains were isolated from adults . Multidrug resistance to various antimicrobial agents was observed in 37.5 per cent of the strains . All the strains were sensitive to ciprofloxacin, norfloxacin and gentamycin.

Indian J Med Res, 1999 Dec, 110, 181 - 2
Copper resistance & its correlation to multiple drug resistance in Salmonella typhi isolates from south Karnataka; Ciraj AM et al.; A study was conducted to ascertain the prevalence of copper resistant Salmonella typhi isolates in south Karnataka . Of the 186 strains studied, 26 (13.97%) were found to be copper resistant . Among the copper resistant strains 19 (73.08%) were found multi drug resistant . All copper resistant strains remained uniformly sensitive to ceftriaxone, ciprofloxacin and norfloxacin . Multiple drug resistance was exclusively associated with E1 phage types.

J Med Ethics, 2000 Feb, 26(1), 9 - 15
Ignorance is bliss? HIV and moral duties and legal duties to forewarn; Bennett R et al.; In 1997, a court in Cyprus jailed Pavlos Georgiou for fifteen months for knowingly infecting a British woman, Janet Pink, with HIV-1 through unprotected sexual intercourse . Pink met Georgiou in January 1994 whilst on holiday . She discovered that she had contracted the virus from him in October 1994 but continued the relationship until July 1996 when she developed AIDS . She returned to the UK for treatment and reported Georgiou to the Cypriot authorities . There have been a number of legal cases involving deliberate transmission of HIV, but most have involved forced exposure to infected bodily fluids for example, rape or biting, and have been dealt with using the existing legislation for rape or assault . While it is often difficult to prove responsibility for transmission in cases of forced exposure to HIV, it is even more contentious in cases like those of Janet Pink where an individual has consented to sex but claims that he/she was not forewarned of his/her partner's HIV-positive status . At present there is no specific criminal offence of having unprotected sexual intercourse without disclosing one's HIV-positive status but a prosecution could possibly be brought under any one of a number of existing offences . Perhaps a change of policy needs to be considered . The Home Office has issued a consultation document which outlines a proposal that will allow the criminalization of intentional transmission of diseases, like HIV, that are likely to cause serious harm . This revised legislation would cover all other potentially fatal diseases (including salmonella and legionnaire's disease, for instance) but seems primarily to be targeted at HIV transmission . Should transmission of HIV through consensual sex, without the HIV-positive status of the individual being disclosed, be an offence? This question, and that of whether there is a moral obligation to disclose a positive HIV status prior to having a sexual relationship is the subject of this paper.

Arch Pediatr, 2000 Feb, 7(2), 154 - 7
{Acute Salmonella typhi meningitis in a 25-day-old newborn infant complicated by obstruction of the sylvian artery}; Kay's Kayemba S et al.; Acute Salmonella typhi meningitis is rare in neonates, mostly reported from developing countries with poor socioeconomic conditions . CASE REPORT: A male Caucasian newborn presented with acute Salmonella typhi meningitis at the age of 25 days . His parents had traveled across several African countries under rudimentary hygienic conditions a few months before his birth . Despite early and adapted antibiotic therapy (cefotaxime plus netilmycine), the child developed ischemia in the region of the left sylvian artery . CONCLUSION: Salmonella meningitis must be considered while dealing with a sick newborn whose mother has traveled across countries with endemic typhoid.

Appl Environ Microbiol, 2000 Mar, 66(3), 1216 - 9
Development of a nonantibiotic dominant marker for positively selecting expression plasmids in multivalent Salmonella vaccines; McNeill HV et al.; We report the novel application of a herbicide-resistance-based dominant marker for the positive selection of expression plasmids in Salmonella serovar vaccines . The beta-lactamase gene of the plasmid pTETnir15, which expresses fragment C of tetanus toxin (TetC), has been replaced with the bar gene marker . The new plasmid pBAT1 can be positively selected in vitro within Salmonella serovars in the presence of the herbicide DL-phosphinothricin . The expression of TetC remains unaltered, and the Salmonella enterica serovar Typhimurium vaccine strain is stable and immunogenic in vivo.

Surg Neurol, 2000 Jan, 53(1), 86 - 90
Multiple brain abscesses caused by Salmonella typhi: case report; Hanel RA et al.; BACKGROUND: Focal intracranial infections caused by Salmonella species are uncommon . The authors report a case of multiple brain abscesses caused by Salmonella typhi . CASE DESCRIPTION: A 2-month-old girl was admitted to the hospital because of diarrhea, vomiting, fever, and poor feeding . Neurological examination revealed cervical hyperextension and absence of sucking and Moro reflexes . During the next 20 hours she developed complex partial seizures with secondary generalization and alternated irritability with drowsiness . Investigation showed hemoglobin 6.3 g/dl; white blood cell count of 19500/mm3 with a marked shift to the left . The analysis of the cerebrospinal fluid revealed white cell count of 1695/mm3, lymphocytes 61%, protein 300 mg/dl and glucose 6 mg/dl . The patient was treated for acute gastroenterocolitis, sepsis, and meningitis . Blood culture taken on the day of admission showed gram-negative bacilli, later identified as S . typhi . Computed tomography scan demonstrated a lesion in the right parietal lobe compatible with a brain abscess . Follow-up computed tomography after 7 days showed several other lesions with the same features . Surgical drainage of the right parietal lesion was performed on the 13th day, through a burr hole . The patient was discharged 5 weeks after admission without neurological deficit . CONCLUSION: Bacteremia, sepsis, and meningitis are relatively common in children with Salmonella infection but intracranial abscesses are very rare . Surgical drainage combined with prolonged antibiotic therapy (drug of choice: chloramphenicol) is the best treatment for Salmonella brain abscesses . The possibility of intracranial infection should be considered in patients with Salmonellosis and neurological dysfunction.

Can J Microbiol, 1999 Dec, 45(12), 988 - 94
Inhibition of pathogenic Salmonella enteritidis growth mediated by Escherichia coli microcin J25 producing strains; Portrait V et al.; For the first time, microcin-producing strains showing inhibitory activities against enteropathogen Salmonella enteritidis were isolated from poultry intestinal contents . Among the numerous strains isolated, two strains of Escherichia coli, named J02 and J03, showing the greatest activities against S . enteritidis, were studied . Biochemical tests and purification identified the main antagonist compound produced as microcin J25 . In order to evaluate the protective potential of E . coli J02 and J03 against S . enteritidis infection, the ability of these strains to inhibit growth of S . enteritidis was investigated in mixed culture . A strong antagonist activity was obtained with a preculture phase of the active strain in minimal medium before incubation with S . enteritidis . In a bioreactor experiment simulating the chicken gastric and intestinal tract environment, a mixture of the two strains E . coli J02 and J03, provided an enhanced inhibitory effect . Microcinogenic strain activities were not affected by bile, pancreatic enzymes addition, or acidic conditions . These results suggest the relevant role of microcin-producing microorganisms in microbial intestinal ecology . To conclude, this study shows that microcin J25 strains could exert a beneficial protective effect against S . enteritidis growth in situ.

J Biol Chem, 2000 Mar 10, 275(10), 7013 - 20
The RcsAB box . Characterization of a new operator essential for the regulation of exopolysaccharide biosynthesis in enteric bacteria; Wehland M et al.; The interaction of the two transcriptional regulators RcsA and RcsB with a specific operator is a common mechanism in the activation of capsule biosynthesis in enteric bacteria . We describe RcsAB binding sites in the wza promoter of the operon for colanic acid biosynthesis in Escherichia coli K-12, in the galF promoter of the operon for K2 antigen biosynthesis in Klebsiella pneumoniae, and in the tviA (vipR) promoter of the operon for Vi antigen biosynthesis in Salmonella typhi . We further show the interaction of RcsAB with the rcsA promoters of various species, indicating that rcsA autoregulation also depends on the presence of both proteins . The compilation of all identified RcsAB binding sites revealed the conserved core sequence TaAGaatatTCctA, which we propose to be termed RcsAB box . The RcsAB box is also part of Bordetella pertussis BvgA binding sites and may represent a more distributed recognition motif within the LuxR superfamily of transcriptional regulators . The RcsAB box is essential for the induction of Rcs-regulated promoters . Site-specific mutations of conserved nucleotides in the RcsAB boxes of the E . coli wza and rcsA promoters resulted in an exopolysaccharide-negative phenotype and in the reduction of reporter gene expression.

J Clin Microbiol, 2000 Mar, 38(3), 1269 - 71
Multiple clones within multidrug-resistant Salmonella enterica serotype Typhimurium phage type DT104 . The Greek Nontyphoidal Salmonella Study Group; Markogiannakis A et al.; Six distinct clones were present among Greek multidrug-resistant Salmonella enterica serotype Typhimurium phage type DT104, since isolates belonging to resistance phenotypes including the ACSSuT (ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline) core could be distinguished with respect to their pulsed-field gel electrophoresis patterns, int1 integron structures, and presence or absence of antibiotic resistance genes ant(3'')-Ia, pse-1, and tem-1.

J Clin Microbiol, 2000 Mar, 38(3), 1221 - 6
Diagnostic and public health dilemma of lactose-fermenting Salmonella enterica serotype Typhimurium in cattle in the Northeastern United States; McDonough PL et al.; The presence of lactose-fermenting Salmonella strains in clinical case materials presented to microbiology laboratories presents problems in detection and identification . Failure to detect these strains also presents a public health problem . The laboratory methods used in detecting lactose-fermenting Salmonella enterica serotype Typhimurium from six outbreaks of salmonellosis in veal calves are described . Each outbreak was caused by a multiply-resistant and lactose-fermenting strain of S . enterica serotype Typhimurium . The use of Levine eosin-methylene blue agar in combination with screening of suspect colonies for C8 esterase enzyme and inoculation of colonies into sulfide-indole-motility medium for hydrogen sulfide production was particularly effective for their detection . A hypothesis for the creation of lactose-fermenting salmonellae in the environment is presented . It is proposed that the environment and husbandry practices of veal-raising barns provide a unique niche in which lactose-fermenting salmonellae may arise.

Am Surg, 2000 Feb, 66(2), 219 - 22
Intestinal perforation secondary to Salmonella typhi: case report and review of the literature; Stoner MC et al.; The case of a young woman presenting with fever, abdominal distention, and diarrhea is presented . While hospitalized, she developed peritonitis, and a laparotomy was performed emergently . Intraoperative and pathologic examinations are highly suggestive of Salmonella typhi as an etiology for her symptoms and eventual perforation . Salmonella enteritis can be a difficult diagnosis to make, but in most cases it is a self-limited disease process . In a minority of cases, multidrug antibiotic therapy may be required secondary to an increasing prevalence of resistant strains . Patients who perforate require prompt operation to limit morbidity and mortality . Outcome is significantly improved in those patients by directed resection of the affected segment of bowel and by aggressive perioperative care.

Epidemiol Infect, 1999 Dec, 123(3), 431 - 6
Electronic network for monitoring travellers' diarrhoea and detection of an outbreak caused by Salmonella enteritidis among overseas travellers; Osaka K et al.; The Traveller's Diarrhoea Network, by which the Infectious Disease Surveillance Center is electronically connected with two major airport quarantine stations and three infectious disease hospitals, was launched in February 1988 in Japan . The data on travellers' diarrhoea detected is reported weekly by e-mail . Two clusters of infection among travellers returning from Italy were reported by two airport quarantine stations at the end of September 1998 . A total of 12 salmonella isolates from 2 clusters were examined . All were identified as Salmonella enteritidis, phage type 4 and showed identical banding patterns on pulsed-field gel electrophoresis . A case-control study showed that the scrambled eggs served at the hotel restaurant in Rome were the likely source of this outbreak . This outbreak could not have been detected promptly and investigated easily without the e-mail network . International exchange of data on travellers' diarrhoea is important for preventing and controlling food-borne illnesses infected abroad.

Epidemiol Infect, 1999 Dec, 123(3), 423 - 30
Levels of virulence are not determined by genomic lineage of Salmonella enterica serotype Enteritidis strains; Olsen JE et al.; Mouse virulence and the ability to adhere to, and invade cultured MDCK cells were investigated in 38 phage type reference strains of Salmonella enterica serotype Enteritidis and correlated with genomic lineage . The genomic lineage of 11 of the strains was determined in the present study; one IS200 and one ribotype pattern that had not been reported previously were observed . Log c.f.u . in the spleen 10 days post intraperitoneal (i.p.) infection with 3x10(3) bacteria (logVC10) varied between 2.9 and 8.7 . The reference strains of PT7 and PT23 were found to be semi-rough and were of low virulence . All other strains possessed smooth LPS . Within each of the two major clonal lines, as well as among phage types outside these, both highly virulent and moderate to low virulent strains were present . While all strains of PT1, PT2 and PT8 were highly virulent, low virulent strains were detected in PT4 and PT13 . The ability to adhere to, and invade MDCK cells varied between phage types (adherence between 13 and 61% of the inocula and invasion between 4 and 151% of the adherent cells) . The results of the cell culture experiments did not correlate with the results of mouse virulence tests . No correlation between clonal lineage and virulence was found within S . Enteritidis . It seems most likely that some strains have lost some of the essential factors enabling this serotype to cause successful systemic infection.

J Perinatol, 2000 Jan-Feb, 20(1), 54 - 6
Fatal neonatal Salmonella enteritidis sepsis; Pumberger W et al.; A case history of a fatal neonatal infection caused by Salmonella enteritidis group D is reported . The baby deteriorated rapidly at 24 hours after birth with clinical signs and symptoms of an acute abdomen . Bloody diarrhea led to a tentative diagnosis of midgut volvulus or necrotizing enterocolitis . Autopsy and bacteriologic investigation revealed sepsis by S . enteritidis group D . The same organism was found in cultures taken from stool and vaginal swabs from the mother . This clearly confirmed transmission of the infection during delivery.

J Bacteriol, 2000 Mar, 182(6), 1558 - 63
ssrA (tmRNA) plays a role in Salmonella enterica serovar Typhimurium pathogenesis; Julio SM et al.; Escherichia coli ssrA encodes a small stable RNA molecule, tmRNA, that has many diverse functions, including tagging abnormal proteins for degradation, supporting phage growth, and modulating the activity of DNA binding proteins . Here we show that ssrA plays a role in Salmonella enterica serovar Typhimurium pathogenesis and in the expression of several genes known to be induced during infection . Moreover, the phage-like attachment site, attL, encoded within ssrA, serves as the site of integration of a region of Salmonella-specific sequence; adjacent to the 5' end of ssrA is another region of Salmonella-specific sequence with extensive homology to predicted proteins encoded within the unlinked Salmonella pathogenicity island SPI4 . S . enterica serovar Typhimurium ssrA mutants fail to support the growth of phage P22 and are delayed in their ability to form viable phage particles following induction of a phage P22 lysogen . These data indicate that ssrA plays a role in the pathogenesis of Salmonella, serves as an attachment site for Salmonella-specific sequences, and is required for the growth of phage P22.

J Vet Diagn Invest, 2000 Jan, 12(1), 83 - 7
Improved plating media for the detection of Salmonella species with typical and atypical hydrogen sulfide production; Mallinson ET et al.; The Salmonella detection ability of 2 surfactant-supplemental media, xylose-lysine-tergitol (Nia-proof) 4 (XLT4) and Miller-Mallinson (MM) agar, was compared against that of several commonly used plating media . XLT4 and MM appeared to be the most efficient in detecting Salmonella in meat products and food animal environments . MM was superior to XLT4 in detecting those increasingly more prevalent strains of Salmonella possessing weak to ultraweak H2S production characteristics.

Antibiot Khimioter, 2000, 45(1), 21 - 4
{A comparative analysis of the properties of bacteria in the genus Salmonella isolated from children in Latvia}; Grope I et al.; Since social and economic changes in Latvia in 1991 the incidence of salmonellosis dramatically increased: more than 500 pediatric cases are registered every year . Specification of the properties of the Salmonella strains isolated in Latvia was undertaken . The study demonstrated that acute salmonellosis in pediatric inpatients was mainly due to S.typhimurium (78 per cent) and only in 22 per cent of the patients it was due to S.enteritidis . All the S.typhimurium isolates showed high antibiotic resistance defined by specific extended spectrum beta-lactamase (CTX-M-5).

J Travel Med, 2000 Jan, 7(1), 19 - 24
Typhoid fever in group travelers: opportunity for studying vaccine efficacy; Cobelens FG et al.; BACKGROUND: Typhoid fever (TF) is a rare disease among travelers to endemic areas, and little is known about its travel-related epidemiology . In addition, efficacy data on TF vaccines in travelers is scanty . During 3 months of 1994/95, six cases of TF were reported in The Netherlands among participants of four package tours to Indonesia provided by the same operator . The present study was designed to describe the epidemiology of TF in these groups, and to assess whether travel groups can be used for studying the efficacy of TF vaccines in travelers . METHOD: Questionnaire-based historical cohort study of participants of 4 groups that stayed in the same hotels along their tours (n=156) . TF was defined as blood culture-confirmed Salmonella typhi infection . Submitted isolates were typed by antigen and phage typing . Immunization status was considered documented if ascertained by written records . RESULTS: Among 110 participants (71%), six cases of TF were identified (group specific attack rate AR 5.4%), three of which were from one travel group (AR 12.0%) . There were no significant differences by age or sex . Three submitted S . typhi isolates showed three different types, two of which were in the same group . Eighty-three percent of respondents reported documented TF vaccination in the preceding 3 years . All cases occurred in recipients of the oral Ty21a vaccine (AR 10.2%, 95% CI 3.8-20.8%), but differences with nonvaccinees and recipients of the heat-inactivated whole cell or Vi-antigen polysaccharide vaccines were not significant . CONCLUSIONS: Although TF is rare in travelers, infections with different strains of S . typhi can occur in one travel group . Travel groups offer an opportunity for retrospective assessment of vaccine efficacy, provided that equal chance of exposure is largely guaranteed; case ascertainment is maximally specific and similar in the vaccine groups; vaccine status is ascertained accurately; and prior immunity by previous exposures to and use of antibiotics effective against the infection are excluded from, or controlled for in, the analysis.

J Travel Med, 2000 Jan, 7(1), 15 - 8
Etiology of travelers' diarrhea on a Caribbean island; Paredes P et al.; BACKGROUND: Between December 6, 1994 and March 10, 1996, a study of the etiology of diarrhea was carried out among 332 travelers to five all-inclusive hotels in Negril, Jamaica . METHODS: Stool specimens were collected and sent to Montego Bay for laboratory analysis . Escherichia coli strains isolated at the Jamaican laboratory were sent to Houston for toxin testing . RESULTS: A recognized enteropathogen was found in 118 of the 332 (35.5%) cases . Enterotoxigenic E . coli (ETEC) were the most commonly identified pathogen (87/332; 26.2%) followed by Salmonella (4.2%) and Shigella (4.2%) . Clustering of etiologically defined cases was studied at each hotel . A cluster was defined as 2 or more cases with the same pathogen identified in the same hotel within 7 days . In the 3 hotels with the highest number of cases of diarrhea, enteropathogens were part of a cluster in 65 of 99 cases (65.7%) of diarrhea of which an etiologic agent was identified . In the other 2 hotels, only 4 of 20 cases (20%) occurred in clusters . CONCLUSIONS: A total of 25 clusters of travelers' diarrhea cases was detected at the five hotels during the study period . Seventeen of 25 (68%) ETEC isolations occurred as part of a clustering of diarrhea cases . The largest outbreak of pathogen-identified diarrhea consisted of 7 cases of ETEC producing both heat-stable and heat-labile enterotoxins . In the Jamaican hotels with all inclusive meal packages most diarrhea cases occurred as small clusters, presumably as the result of foodborne outbreaks.

Am J Infect Control, 2000 Feb, 28(1), 54 - 7
Direct costs associated with a nosocomial outbreak of Salmonella infection: an ounce of prevention is worth a pound of cure; Spearing NM et al.; BACKGROUND: Nosocomial outbreaks of Salmonella infections in Australia are an infrequent but significant source of morbidity and mortality . Such an outbreak results in direct, measurable expenses for acute care management, as well as numerous indirect (and less quantifiable) costs to those affected, the hospital, and the wider community . This article describes the significant direct costs incurred as a result of a nosocomial outbreak of Salmonella infection involving patients and staff . METHOD: Information on costs incurred by the hospital was gathered from a number of sources . The data were grouped into 4 sections (medical costs, investigative costs, lost productivity costs, and miscellaneous) with use of an existing tool for calculating the economic impact of foodborne illness . RESULTS: The outbreak cost the hospital more than AU $120, 000 . (US $95,000) . This amount is independent of more substantial indirect costs . CONCLUSION: Salmonella infections are preventable . Measures to aid the prevention of costly outbreaks of nosocomial salmonellosis, although available, require an investment of both time and money . We suggest that dedication of limited resources toward such preventive strategies as education is a practical and cost-effective option for health care facilities.

Infect Immun, 2000 Mar, 68(3), 1549 - 56
Construction and characterization of a Salmonella enterica serovar typhimurium clone expressing a salivary adhesin of Streptococcus mutans under control of the anaerobically inducible nirB promoter; Huang Y et al.; Attenuated Salmonella enterica serovar Typhimurium has been used for targeted delivery of recombinant antigens to the gut-associated lymphoid tissues . One potential problem associated with this vaccine approach is the likelihood of in vivo instability of the plasmid constructs caused by constitutive hyperexpression of the heterologous immunogen . The aim of this study was to generate and characterize an expression system encoding the saliva-binding region (SBR) of Streptococcus mutans antigen I/II adhesin, either alone or linked with the mucosal adjuvant cholera toxin A2/B subunits (CTA2/B), under the control of the inducible nirB promoter . This promoter is activated in an anaerobic environment and within macrophages, which are the primary antigen-presenting cells involved in phagocytosis and processing of Salmonella . The gene encoding the chimeric SBR-CTA2/B was amplified by PCR using primers containing appropriate restriction sites for subcloning into pTETnirB, which contains the nirB promoter . The resulting plasmid was introduced into serovar Typhimurium by electroporation . Production of the SBR-CTA2/B chimeric protein under anaerobic conditions was verified by enzyme-linked immunosorbent assay of whole-cell lysates on plates coated with G(M1) ganglioside and developed with antibodies to SBR . Similar procedures were followed for cloning the gene encoding SBR in serovar Typhimurium under nirB control . Anaerobic expression of SBR was confirmed by Western blotting of whole-cell lysates probed with anti-SBR antibodies . The resulting serovar Typhimurium strains were administered by either the oral or the intranasal route to mice, and colonization was assessed by microbiologic analysis of dissociated spleens, Peyer's patches (PP), and nasal tissues . High numbers of the recombinant strains persisted in PP and spleen for at least 21 days following oral challenge . A single intranasal administration of the Salmonella clones to mice also resulted in the colonization of the nasal tissues by the recombinant bacteria . Salmonellae were recovered from nasal lymphoid tissues, superficial lymph nodes, internal jugular lymph nodes, PP, and spleens of mice for at least 21 days after challenge . This study provides quantitative evidence for colonization by Salmonella strains expressing a recombinant protein under the control of the inducible nirB promoter in PP or nasal tissues following a single oral or nasal administration of the bacteria, respectively.

Infect Immun, 2000 Mar, 68(3), 1529 - 34
Phase 1 and phase 2 studies of Salmonella enterica serovar paratyphi A O-specific polysaccharide-tetanus toxoid conjugates in adults, teenagers, and 2- to 4-year-old children in Vietnam; Konadu EY et al.; Salmonella enterica serovar Paratyphi A O-specific polysaccharide (O-SP) was activated with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) and bound to tetanus toxoid (TT) with adipic acid dihydrazide as a linker (SPA-TT(1)) or directly (SPA-TT(2)) . In mice, these two conjugates elicited high levels of immunoglobulin G (IgG) anti-lipopolysaccharide (LPS) in serum with bactericidal activity (E . Konadu, J . Shiloach, D . A . Bryla, J . B . Robbins, and S . C . Szu, Infect . Immun . 64:2709-2715, 1996) . The safety and immunogenicity of the two conjugates were then evaluated sequentially in Vietnamese adults, teenagers, and 2- to 4-year-old children . None of the vaccinees experienced significant side effects, and all had preexisting LPS antibodies . At 4 weeks after injection, there were significant increases of the geometric mean IgG and IgM anti-LPS levels in the adults and teenagers: both conjugates elicited a greater than fourfold rise in the IgG anti-LPS level in serum in >/=80% of the volunteers . SPA-TT(2) elicited slightly higher, though not statistically significantly, levels of IgG anti-LPS than did SPA-TT(1) in these age groups . Accordingly, only SPA-TT(2) was evaluated in the 2- to 4-year-old children . On a random basis, one or two injections were administered 6 weeks apart to the children . No significant side effects were observed, and the levels of preexisting anti-LPS in serum were similar in children of all ages . A significant rise in the IgG anti-LPS titer was elicited by the first injection (P = 0.0001); a second injection did not elicit a booster response . Representative sera from all groups had bactericidal activity that could be adsorbed by S . enterica serovar Paratyphi A LPS.

Infect Immun, 2000 Mar, 68(3), 1196 - 201
Phase 2 clinical trial of attenuated Salmonella enterica serovar typhi oral live vector vaccine CVD 908-htrA in U.S . volunteers; Tacket CO et al.; Salmonella enterica serovar Typhi strain CVD 908-htrA is a live attenuated strain which may be useful as an improved oral typhoid vaccine and as a vector for cloned genes of other pathogens . We conducted a phase 2 trial in which 80 healthy adults received one of two dosage levels of CVD 908-htrA in a double-blind, placebo-controlled, crossover study . There were no differences in the rates of side effects among volunteers who received high-dose vaccine (4.5 x 10(8) CFU), lower-dose vaccine (5 x 10(7) CFU), or placebo in the 21 days after vaccination, although recipients of high-dose vaccine (8%) had more frequent diarrhea than placebo recipients (0%) in the first 7 days . Seventy-seven percent and 46% of recipients of high- and lower-dose vaccines, respectively, briefly excreted vaccine organisms in their stools . All blood cultures were negative . Antibody-secreting cells producing antilipopolysaccharide (LPS) immunoglobulin A (IgA) were detected in 100 and 92% of recipients of high- and lower-dose vaccines, respectively . Almost half the volunteers developed serum anti-LPS IgG . Lymphocyte proliferation and gamma interferon production against serovar Typhi antigens occurred in a significant proportion of vaccinees . This phase 2 study supports the further development of CVD 908-htrA as a single-dose vaccine against typhoid fever and as a possible live vector for oral delivery of other vaccine antigens.

Infect Immun, 2000 Mar, 68(3), 1109 - 15
Salmonella enterica serovar typhimurium surA mutants are attenuated and effective live oral vaccines; Sydenham M et al.; A previously described attenuated TnphoA mutant (BRD441) of Salmonella enterica serovar Typhimurium C5 (I . Miller, D . Maskell, C . Hormaeche, K . Johnson, D . Pickard, and G . Dougan, Infect . Immun . 57:2758-2763, 1989) was characterized, and the transposon was shown to be inserted in surA, a gene which encodes a peptidylprolyl-cis, trans-isomerase . A defined surA deletion mutation was introduced into S . enterica serovar Typhimurium C5 and the mutant strain, named S . enterica serovar Typhimurium BRD1115, was extensively characterized both in vitro and in vivo . S . enterica serovar Typhimurium BRD1115 was found to be defective in the ability to adhere to and invade eukaryotic cells . Furthermore, S . enterica serovar Typhimurium BRD1115 was attenuated by at least 3 log units when administered orally or intravenously to BALB/c mice . Complementation of the mutation with a plasmid carrying the intact surA gene almost completely restored the virulence of BRD1115 . In addition, S . enterica serovar Typhimurium BRD1115 demonstrated potential as a vaccine candidate, since mice immunized with BRD1115 were protected against subsequent challenge with S . enterica serovar Typhimurium C5 . S . enterica serovar Typhimurium BRD1115 also showed potential as a vehicle for the effective delivery of heterologous antigens, such as the nontoxic, protective fragment C domain of tetanus toxin, to the murine immune system.

Infect Immun, 2000 Mar, 68(3), 1086 - 93
Cloning of porcine NRAMP1 and its induction by lipopolysaccharide, tumor necrosis factor alpha, and interleukin-1beta: role of CD14 and mitogen-activated protein kinases; Zhang G et al.; The gene for natural resistance-associated macrophage protein 1 (NRAMP1) plays a dominant role in controlling the resistance of inbred mice to infection with intracellular bacteria, such as Mycobacteria, Salmonella, and Leishmania . NRAMP1 is a membrane protein with a consensus transport motif present in one of the intracellular loops . Although its functions remain unclear, recent clues suggest that NRAMP1 protein plays a potential role in ion transport, which presumably accounts for the ability of this single protein to regulate the intraphagosomal replication of several species of antigenically unrelated intracellular pathogens . Expression of NRAMP1 in mice can be induced by lipopolysaccharide (LPS) or bacterial infection; however, little is known about the mechanisms of induction . Here, we report the cloning of the full-length cDNA for porcine NRAMP1, which had over 85% identity in amino acid sequence to its congeners from humans, mice, cattle, and sheep . As for its mammalian congeners, expression of porcine NRAMP1 mRNA was cell and tissue specific and was highest in macrophages . Investigation of the molecular mechanisms by which NRAMP1 is induced showed that LPS-induced expression in macrophages, neutrophils, and peripheral blood mononuclear cells was time and dose dependent and was mediated primarily through CD14 . Induction of NRAMP1 required de novo protein synthesis, and mitogen-activated protein kinases (MAPK) were essential . Blockage of either p38 or p42/44 MAPK pathways suppressed the expression of NRAMP1 to basal levels . These findings suggest that bacterial infection and proinflammatory mediators induce NRAMP1 expression via activation of MAPK pathways.

Infect Immun, 2000 Mar, 68(3), 1005 - 13
Differential bacterial survival, replication, and apoptosis-inducing ability of Salmonella serovars within human and murine macrophages; Schwan WR et al.; Salmonella serovars are associated with human diseases that range from mild gastroenteritis to host-disseminated enteric fever . Human infections by Salmonella enterica serovar Typhi can lead to typhoid fever, but this serovar does not typically cause disease in mice or other animals . In contrast, S . enterica serovar Typhimurium and S . enterica serovar Enteritidis, which are usually linked to localized gastroenteritis in humans and some animal species, elicit a systemic infection in mice . To better understand these observations, multiple strains of each of several chosen serovars of Salmonella were tested for the ability in the nonopsonized state to enter, survive, and replicate within human macrophage cells (U937 and elutriated primary cells) compared with murine macrophage cells (J774A.1 and primary peritoneal cells); in addition, death of the infected macrophages was monitored . The serovar Typhimurium strains all demonstrated enhanced survival within J774A.1 cells and murine peritoneal macrophages, compared with the significant, almost 100-fold declines in viable counts noted for serovar Typhi strains . Viable counts for serovar Enteritidis either matched the level of serovar Typhi (J774A . 1 macrophages) or were comparable to counts for serovar Typhimurium (murine peritoneal macrophages) . Apoptosis was significantly higher in J774A.1 cells infected with serovar Typhimurium strain LT2 compared to serovar Typhi strain Ty2 . On the other hand, serovar Typhi survived at a level up to 100-fold higher in elutriated human macrophages and 2- to 3-fold higher in U937 cells compared to the serovar Typhimurium and Enteritidis strains tested . Despite the differential multiplication of serovar Typhi during infection of U937 cells, serovar Typhi caused significantly less apoptosis than infections with serovar Typhimurium . These observations indicate variability in intramacrophage survival and host cytotoxicity among the various serovars and are the first to show differences in the apoptotic response of distinct Salmonella serovars residing in human macrophage cells . These studies suggest that nonopsonized serovar Typhimurium enters, multiplies within, and causes considerable, acute death of macrophages, leading to a highly virulent infection in mice (resulting in death within 14 days) . In striking contrast, nonopsonized serovar Typhi survives silently and chronically within human macrophages, causing little cell death, which allows for intrahost dissemination and typhoid fever (low host mortality) . The type of disease associated with any particular serovar of Salmonella is linked to the ability of that serovar both to persist within and to elicit damage in a specific host's macrophage cells.

J Nucl Med, 2000 Feb, 41(2), 215 - 9
99mTc-human serum albumin scans in children with protein-losing enteropathy; Halaby H et al.; Protein-losing enteropathy (PLE) can be diagnosed scintigraphically using 99mTc-human serum albumin (HSA) scans . METHODS: To evaluate the usefulness of this method in detecting enteric protein loss, we retrospectively reviewed the 99mTc-HSA scans of 18 children presenting consecutively with PLE . RESULTS: Enteric 99mTc-HSA uptake was noted in 12 patients (8 boys, 4 girls) with a mean age of 7.4 y . Early dynamic images showed abdominal uptake that was most likely in the small bowel in 91% of the scans . Delayed images showed abnormal accumulation that was localized in the colon in 73% and in the small bowel in 27% of the scans . A 4-mo follow-up scan obtained in 3 patients showed reduced HSA uptake after a high-protein, low-fat, medium-chain triglyceride oil-based diet and fat-soluble vitamins . Mean serum albumin, total protein, gammaglobulin, and calcium levels were significantly decreased . Ten patients (from 4 families) were diagnosed to have primary intestinal lymphangectasia . One patient had active Salmonella enterocolitis, and 1 had giardiosis . 99mTc-HSA was normal in the remaining 6 patients (3 boys, 3 girls) with a mean age of 3.5 y (range, 2-5 y) . Mean serum albumin, total protein, gammaglobulin, and calcium levels were less decreased than those of the first group . Five of these patients had primary intestinal lymphangactesia (associated with infantile systemic hyalinosis in 1 patient) . The remaining patient had normal duodenal biopsy, and the cause of protein loss remained unknown . CONCLUSION: The 99mTc-HSA scan is useful in the evaluation of children with PLE, especially those with severe hypoproteinemia and hypoalbuminemia, presumably reflecting a high rate of protein loss.

Indian J Exp Biol, 1999 Sep, 37(9), 925 - 32
Detection, prevalence, purification and characterization of lecithinase of Klebsiella pneumoniae; Singh BR et al.; Lecithinase activity in Klebsiella is a rare trait as out of 208 strains of Klebsiella belonging to 3 species, viz . K . pneumoniae (168), K . planticola (29) and K . oxytoca (11), only 4 strains of K . pneumoniae produced lecithinase positive colonies on egg-yolk-agar . Although cell lysates of 16 K . pneumoniae yielded positive results for lecithinase assay on egg-yolk-agar, 19 strains were detected positive for lecithinase with ELISA using anti-lecithinase serum . Release of up to 52.12% cell-bound lecithinase could be achieved with polymyxin-B treatment at 100 micrograms/ml concentration . Purified lecithinase was determined to be a high molecular weight (70 kDa), crystalizable, anionic (pI, 3.5) protein . It possessed cytolytic, haemolytic and dermonecrotic activities but did not induce fluid accumulation in rabbit ileal loop or infant mouse guts . It was inactivated by boiling, trypsin and chymotrypsin treatment and alkaline pH . Serologically, it was related to lecithinase of Aeromonas caviae and phospholipase-C of Salmonella.

Phytother Res, 2000 Mar, 14(2), 112 - 7
Antibacterial activity of diospyrin, isodiospyrin and bisisodiospyrin from the root of Diospyros piscatoria (Gurke) (Ebenaceae); Adeniyi BA et al.; Two dimeric naphthoquinones, diospyrin and isodiospyrin, isolated from the root of Diospyros piscatoria (Gurke), a common ingredient in several folk medicines, have been shown to have a broad spectrum of antibacterial activity . The minimum inhibitory concentrations (MICs) of diospyrin against Streptococcus pyogenes ATCC 12344 and Streptococcus pneumoniae ATCC 33400 ranged from 1.56 to 50 microg/mL . While those against Salmonella choleraesuis serotype typhi (S . typhi), ATCC 6539 and Mycobacterium chelonae ATCC 19977 were between 25 and 100 microg/mL . Isodiospyrin was more active than its racemic isomer diospyrin . The MICs against Gram-positive bacteria ranged from 0.78 to 50 microg/mL . While those against Pseudomonas aeruginosa ATCC 15443 and S . typhi ranged from 50 to 100 microg/mL . The MIC for M . chelonae was between 6.25 and 25 microg/mL . MICs were found to increase with the concentration of cells used for the inoculum . The MICs for Bacillus subtilis ATCC 6633 increased up to the highest concentration of cells tested . The same phenomenon was observed on M . chelonae, but with better effect in the latter . The kinetics of bacteria studies against both B . subtilis and M . chelonae increases with increasing concentration of isodiospyrin tested . Two tetrameric forms of plumbagin were isolated . The naphthoquinone bisisodiospyrin, gave MIC values between 300 and 400 micro g/mL . The second, as yet unidentified tetramer, was not active at 500 micro g/mL .

Food Chem Toxicol, 2000 Jan, 38(1), 1 - 5
Mutagenicity and antimutagenicity studies of tannic acid and its related compounds; Chen SC et al.; Tannic acid and its hydrolysed products such as ellagic acid, gallic acid and propyl gallate were tested for mutagenicities using Ames Salmonella tester strains TA98 and TA100 . Also, the antimutagenic activities of these compounds against a number of direct mutagens including 2-nitrofluorene (2-NF), 4,4'-dinitro-2-biphenylamine, 1-nitropyrene, 1,3-dinitropyrene, 2-nitro-p-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine were tested . None of these tannic acid compounds was mutagenic . They also failed to show antimutagenic activity towards the tested direct mutagens . However, tannic acid at non-growth inhibitory concentrations reduced the revertant numbers of TA98 in the presence of S9 mix when benzidine, 3,3'-4,4'-tetraminobiphenyl, 4-aminobiphenyl, and N,N-N', N'-tetramethylbenzidine were used as the mutagens . These results suggest that tannic acid, but not its hydrolytic products, affects the metabolic activation of these mutagens.

J Cell Biol, 2000 Feb 21, 148(4), 741 - 53
Live Salmonella recruits N-ethylmaleimide-sensitive fusion protein on phagosomal membrane and promotes fusion with early endosome; Mukherjee K et al.; To understand intracellular trafficking modulations by live Salmonella, we investigated the characteristics of in vitro fusion between endosomes and phagosomes containing live (LSP) or dead Salmonella (DSP) . We observed that fusion of both DSP and LSP were time, temperature and cytosol dependent . GTPgammaS and treatment of the phagosomes with Rab-GDI inhibited fusion, indicating involvement of Rab-GTPases . LSP were rich in rab5, alpha-SNAP, and NSF, while DSP mainly contained rab7 . Fusion of endosomes with DSP was inhibited by ATP depletion, N-ethylmaleimide (NEM) treatment, and in NEM-sensitive factor (NSF)-depleted cytosol . In contrast, fusion of endosomes with LSP was not inhibited by ATP depletion or NEM treatment, and occurred in NSF-depleted cytosol . However, ATPgammaS inhibited both fusion events . Fusion of NEM-treated LSP with endosomes was abrogated in NSF- depleted cytosol and was restored by adding purified NSF, whereas no fusion occurred with NEM-treated DSP, indicating that NSF recruitment is dependent on continuous signals from live Salmonella . Binding of NSF with LSP required prior presence of rab5 on the phagosome . We have also shown that rab5 specifically binds with Sop E, a protein from Salmonella . Our results indicate that live Salmonella help binding of rab5 on the phagosomes, possibly activate the SNARE which leads to further recruitment of alpha-SNAP for subsequent binding with NSF to promote fusion of the LSP with early endosomes and inhibition of their transport to lysosomes.

FEMS Immunol Med Microbiol, 2000 Mar, 27(3), 235 - 40
Apoptosis of human keratinocytes after bacterial invasion; Nuzzo I et al.; In this study, we examined the invasive capacity of Staphylococcus aureus and Salmonella typhi in human keratinocytes and monitored the number of viable intracellular bacteria at different post-infection times . The strains tested entered keratinocytes; both S . typhi and S . aureus were internalized within 30 min to 2 h after infection . No intracellular multiplication was observed, but S . typhi and S . aureus remained viable 72 h after infection . We also demonstrated that keratinocyte death following S . typhi and S . aureus invasion occurs by apoptosis as shown by DNA fragmentation . After 24 h of infection with S . typhi, the number of cells undergoing apoptosis were higher compared to infection with S . aureus . For prolonged infection times (48 h, 72 h) with both bacteria, there was no significant change in the number of cells undergoing apoptosis . The results demonstrated that viable intracellular S . typhi and S . aureus induced apoptosis in keratinocyte cells.

J Biol Chem, 2000 Feb 25, 275(8), 5794 - 803
Acetyl-CoA synthetase from the amitochondriate eukaryote Giardia lamblia belongs to the newly recognized superfamily of acyl-CoA synthetases (Nucleoside diphosphate-forming); Sanchez LB et al.; The gene coding for the acetyl-CoA synthetase (ADP-forming) from the amitochondriate eukaryote Giardia lamblia has been expressed in Escherichia coli . The recombinant enzyme exhibited the same substrate specificity as the native enzyme, utilizing acetyl-CoA and adenine nucleotides as preferred substrates and less efficiently, propionyl- and succinyl-CoA . N- and C-terminal parts of the G . lamblia acetyl-CoA synthetase sequence were found to be homologous to the alpha- and beta-subunits, respectively, of succinyl-CoA synthetase . Sequence analysis of homologous enzymes from various bacteria, archaea, and the eukaryote, Plasmodium falciparum, identified conserved features in their organization, which allowed us to delineate a new superfamily of acyl-CoA synthetases (nucleoside diphosphate-forming) and its signature motifs . The representatives of this new superfamily of thiokinases vary in their domain arrangement, some consisting of separate alpha- and beta-subunits and others comprising fusion proteins in alpha-beta or beta-alpha orientation . The presence of homologs of acetyl-CoA synthetase (ADP-forming) in such human pathogens as G . lamblia, Yersinia pestis, Bordetella pertussis, Pseudomonas aeruginosa, Vibrio cholerae, Salmonella typhi, Porphyromonas gingivalis, and the malaria agent P . falciparum suggests that they might be used as potential drug targets.

Crit Rev Toxicol, 2000 Jan, 30(1), 1 - 69
Search for compounds that inhibit the genotoxic and carcinogenic effects of heterocyclic aromatic amines; Schwab CE et al.; Over the last 30 years approximately 160 reports have been published on dietary compounds that protect from the mutagenic and carcinogenic effects of heterocyclic aromatic amines (HAAs) . In the first section of this review, the current state of knowledge is briefly summarized . Based on the evaluation of the available data, various protective mechanisms are described, and the use of different methodologies for the detection of protective effects is critically discussed . In most antimutagenicity studies (>70%) bacterial indicators (predominantly Salmonella strain TA98) were used, and about 600 individual compounds and complex mixtures have been identified that attenuate the effects of HAAs . The most frequently used in vivo method to detect protective effects are adduct measurements; anticarcinogenic dietary factors were identified by aberrant crypt foci assays and liver foci tests with rats . The mechanisms of protection include inactivation of HAAs and their metabolites by direct binding, inhibition of enzymes involved in the metabolic activation of the amines, induction of detoxifying enzymes, and interaction with DNA repair processes . The detection spectrum of conventional in vitro mutagenicity assays with metabolically incompetent indicator cells is limited . These procedures reflect only simple mechanisms such as direct binding of the HAAs to pyrroles and fibers . It has been shown that these compounds are also effective in rodents . More complex mechanisms, namely, interactions with metabolic activation reactions are not adequately represented in in vitro assays with exogenous enzyme homogenates, and false-negative as well as false-positive results may be obtained . More appropriate approaches for the detection of protective effects are recently developed test systems with metabolically competent cells such as the human Hep G2 line or primary hepatocytes . SCGE tests and DNA adduct measurements with laboratory rodents enable the detection of antigenotoxic effects in different organs, including those that are targets for tumor induction by the amines . Medium term assays based on aberrant crypt foci in colon and liver foci tests have been used to prove that certain compounds that prevented DNA damage by HAAs also reduced their carcinogenic effects . These experiments are costly and time consuming and, due to the weak induction capacity of the amines, only pronounced anticarcinogenic effects can be detected . Over the years, a large bulk of data on HAA protective compounds has accumulated, but only for a few (e.g., fibers, pyrroles, constituents of teas, and lactic acid bacteria) is there sufficient evidence to support the assumption that they are protective in humans as well.

Curr Opin Microbiol, 2000 Feb, 3(1), 54 - 9
Cellular routes of invasion by enteropathogens; Vazquez-Torres A et al.; The cellular pathways of infection utilized by pathogenic enteric bacteria have important implications for their clinical manifestations . Yersinia reaches Peyer's patches via M cells and uses plasmid-encoded factors to resist phagocytic cells . Shigella also translocates via M cells and incapacitates phagocytes, but subsequently re-enters the epithelium basolaterally to elicit an acute inflammatory response . Salmonella has recently been shown to both colonize Peyer's patches via M cells and independently disseminate to extraintestinal sites via CD18-expressing phagocytes . M cell-mediated entry can lead to gastroenteritis and mucosal antibody production, while systemic dissemination can result in septicemia and elicitation of systemic immune responses.

Antimicrob Agents Chemother, 2000 Mar, 44(3), 533 - 9
Antibacterial efficacy of gentamicin encapsulated in pH-sensitive liposomes against an in vivo Salmonella enterica serovar typhimurium intracellular infection model; Cordeiro C et al.; Encapsulation of gentamicin in liposomes can be used to achieve intracellular delivery and broaden the clinical utility of this drug . We have previously described a novel, rationally designed, pH-sensitive liposomal carrier for gentamicin that has superior in vitro efficacy against intracellular infections compared to the efficacies of both free gentamicin and non-pH-sensitive liposomal controls . This liposomal carrier demonstrated pH-sensitive fusion that was dependent on the presence of unsaturated phosphatidylethanolamine (PE) and the pH-sensitive lipid N-succinyldioleoyl-PE . The pharmacokinetics and biodistribution of the free and liposomal gentamicin were examined in mice bearing a systemic Salmonella enterica serovar Typhimurium infection . Encapsulation of gentamicin in pH-sensitive liposomes significantly increased the concentrations of the drug in plasma compared to those of free gentamicin . Furthermore, the levels of accumulation of drug in the infected liver and spleen were increased by 153- and 437-fold, respectively, as a result of liposomal encapsulation . The increased accumulation of gentamicin in the liver and spleen effected by liposomal delivery was associated with 10(4)-fold greater antibacterial activity than that associated with free gentamicin in a murine salmonellosis model . These pH-sensitive liposomal antibiotic carriers with enhanced in vitro activity could be used to improve both in vivo intracellular drug delivery and biological activity.

SAR QSAR Environ Res, 1999 Dec, 10(6), 533 - 43
Chemical diversity approach for evaluating mechanistic relatedness among toxicological phenomena; Pollack N et al.; The CASE/MULTICASE structure-activity relationship (SAR) system was used to assess a new procedure to investigate the mechanistic relatedness of various toxicological endpoints . The method consisted of predicting the activity of 10,000 randomly selected chemicals using validated and characterized SAR models from a variety of biological and toxicological endpoints . The prevalence of chemicals predicted to possess the ability to induce two or more toxicological effects simultaneously should provide a measure of the mechanistic relatedness of these phenomena . Eight toxicological endpoints were predicted and the results were compared to predictions based on an eye irritation SAR model . Allergic contact dermatitis demonstrated a 29.6% greater than expected overlap between expected and observed results (p < 0.001) . Similar results were seen for respiratory hypersensitivity (33.1%), sensory irritation (28.9%), cell toxicity (25.9%), and Ah receptor binding (19.8%) . A lesser degree of overlap was seen between eye irritation and Salmonella mutagenicity (11.5%) and the inhibition of gap junction intercellular communication (6.7%) . Moreover, a negative overlap, suggesting possibly an antagonistic phenomena, was observed between eye irritation and alpha 2 mu-induced nephropathy . These results indicate that this method can provide a useful tool to investigate mechanistic relatedness between diverse toxicological endpoints.

Rev Environ Health, 1999 Jul-Sep, 14(3), 103 - 20
3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX): toxicological properties and risk assessment in drinking water; Hirose A et al.; MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone), one of the byproducts formed during the chlorine disinfection process of drinking water, shows strong mutagenic activity for Salmonella strains in the Ames test . In several countries, the contribution of MX to the total mutagenicity of drinking water is estimated to range from 7% to 67% . To assess the risk of MX for human health, we summarized the toxicological properties of MX and estimated the tolerable daily intake (TDI) or tolerable concentration in drinking water . MX is genotoxic in cultured mammalian cells and causes in vivo DNA damage in several tissues . MX is carcinogenic for rodents in addition to possessing skin and gastric promotion activities . From these toxicological profiles of MX, we estimated the virtual safety dose (VSD) for genotoxic action as 5 ng/kg/d and the TDI for non-genotoxic action of MX as 40 ng/kg/d . We assumed a tolerable MX concentration of 150 ng/L in drinking water . Because of the uncertainty about human genotoxicity, however, and the lack of information on reproductive or developmental toxicity, the estimated tolerable dose level may be provisional.

Br J Surg, 2000 Feb, 87(2), 186 - 90
Spontaneous carotid artery aneurysms; Nair R et al.; BACKGROUND: Spontaneous carotid artery aneurysms are infrequently reported, and are almost always non-atherosclerotic . METHODS: The records of 29 patients with a spontaneous carotid aneurysm treated in an academic vascular unit between 1990 and 1998 were reviewed . RESULTS: All 29 patients were black South Africans; three had bilateral aneurysms . There were 24 men and five women, of mean age 35 (range 13-62) years . Some 25 aneurysms involved the common carotid artery, 12 of which affected the bifurcation, and seven were located in the internal carotid artery . Twenty-five aneurysms were managed surgically, four of which were ligated owing to sepsis . Histo- logical evaluation showed human immunodeficiency virus-related arteritis in four, tuberculous aneurysms in ten, Takayasu's arteritis in two, atherosclerosis in three and non-specific chronic inflammation in four patients . Microbiological examination was negative in all but one patient who had Salmonella sp . cultured . Outcome was generally favourable, but one patient died from massive hemispheric infarction . There were no other new neurological deficits . CONCLUSION: Carotid aneurysms pose a considerable surgical challenge but are amenable to operative intervention with good result . Ligation appears to be well tolerated in this group of predominantly non-atherosclerotic aneurysms.

J Bacteriol, 2000 Mar, 182(5), 1437 - 41
Mutational analysis of ligand recognition by tcp, the citrate chemoreceptor of Salmonella enterica serovar typhimurium; Iwama T et al.; The chemoreceptor Tcp mediates taxis to citrate . To identify citrate-binding residues, we substituted cysteine for seven basic or polar residues that are chosen based on the comparison of Tcp with the well-characterized chemoreceptors . The results suggest that Arg-63, Arg-68, Arg-72, Lys-75, and Tyr-150 (and probably other unidentified residues) are involved in the recognition of citrate.

J Bacteriol, 2000 Mar, 182(5), 1432 - 6
Novel missense mutations that affect the transport function of MalK, the ATP-binding-cassette subunit of the Salmonella enterica serovar typhimurium maltose transport system; Hunke S et al.; We report on novel mutations in the malK gene of Salmonella enterica serovar Typhimurium, encoding the ATPase subunit of the maltose transporter (MalFGK(2)) . Biochemical analysis suggests that (i) L86 might be involved in a signaling step during substrate translocation and (ii) E306 may be critical for the structural integrity of the protein.

Comp Immunol Microbiol Infect Dis, 2000 Mar, 23(2), 73 - 89
Disease patterns in field and bank vole populations during a cyclic decline in central Finland; Soveri T et al.; Declining field vole (Microtus agrestis) and bank vole (Clethrionomys glareolus) populations were sampled (117 field voles and 34 bank voles) in south-central Finland during the winter of 1988-89 . The last surviving field voles were caught in April and bank voles in February . A subsample (16) of the April field voles were taken live to the laboratory for immunosuppression . The histopathology of the main internal organs and the presence of aerobic bacteria and certain parasites were studied . In the lungs, an increase in lymphoid tissue, probably caused by infections, was the most common finding (52% of all individuals) . The prevalences in the voles, in the whole material, of Chrysosporium sp . and Pneumocystis carinii in lungs were 13 and 10% in field voles, and 9 and 0% in bank voles, respectively . Cysts of Taenia mustelae (9 and 27%) were the most common pathological changes in the liver . Enteritis was also rather common (14 and 34%) . In field voles the prevalences of Frenkelia sp . in the brain and Sarcocystis sp . in leg muscles were low (both 6%) . Bordetella bronchiseptica was commonly (31%) isolated from field vole lungs and Listeria monocytogenes from the intestines (34%) . Salmonella spp . could not be found . The dynamics and abundance of inflammations in the lungs and intestines, as well as B . bronchiseptica isolations from the lungs, indicate that obvious epidemics took place in declining vole populations . Of the Luhanka subsample of 16 field voles brought to the laboratory in April, one died of listeriosis, two of Bordetella, and five died for unknown reasons . Even if small mustelids are the driving force in microtine cycles, it is possible that diseases also contribute to the decline.

Br Poult Sci, 1999 Dec, 40(5), 706 - 8
Production and physical characteristics of composted poultry carcases; Lawson MJ et al.; 1 . Experiments were designed to determine whether composting could be a safe and effective method for the disposal of poultry carcases in the UK climate . Laying hen carcases (125) were composted in a wooden compost bin over autumn and winter months, using the United States Department of Agriculture method . 2 . The process took 8 weeks and effectively decomposed the carcases to leave only leg and breast bones . The compost was turned once, which ensured that all the material reached the high temperatures (60 degrees to 70 degrees C) required to control pathogens . Salmonella was fully heat-inactivated, indicating that many poultry-associated bacterial pathogens would also have been inactivated . 3 . It is concluded that this method is suitable for use in the UK and provides a sanitised fertiliser supplement.

J Mol Biol, 2000 Feb 18, 296(2), 361 - 72
Salmonella enteritidis fimbriae displaying a heterologous epitope reveal a uniquely flexible structure and assembly mechanism; White AP et al.; Two distinct Salmonella fimbrins, AgfA and SefA, comprising thin aggregative fimbriae SEF17 and SEF14, respectively, were each genetically engineered to carry PT3, an alpha-helical 16-amino acid Leishmania T-cell epitope derived from the metalloprotease gp63 . To identify regions within AgfA and SefA fimbrins amenable to replacement with this epitope, PCR-generated chimeric fimbrin genes were constructed and used to replace the native chromosomal agfA and sefA genes in Salmonella enteritidis . Immunoblot analysis using anti-SEF17 and anti-PT3 sera demonstrated that all ten AgfA chimeric fimbrin proteins were expressed by S . enteritidis under normal growth conditions . Immunoelectron microscopy confirmed that eight of the AgfA::PT3 proteins were effectively assembled into cell surface-exposed fimbriae . The PT3 replacements in AgfA altered Congo red (CR) binding, cell-cell adhesion and cell surface properties of S . enteritidis to varying degrees . However, these chimeric fimbriae were still highly stable, being resistant to proteinase K digestion and requiring harsh formic acid treatment for depolymerization . In marked contrast to AgfA, none of the chimeric SefA proteins were expressed or assembled into fimbriae . Since each PT3 replacement constituted over 10% of the AgfA amino acid sequence and all ten replacements collectively represented greater than 75% of the entire AgfA primary sequence, the ability of AgfA to accept large sequence substitutions and still assemble into fibers is unique among fimbriae and other structural proteins . This structural flexibility may be related to the novel fivefold repeating sequence of AgfA and its recently proposed structure Proper formation of chimeric fimbrial fibers suggests an unusual assembly mechanism for thin aggregative fimbriae which tolerates aberrant structures . This study opens a range of possibilities for Salmonella thin aggregative fimbriae as a carrier of heterologous epitopes and as an experimental model for studies of protein structure .

Acta Crystallogr D Biol Crystallogr, 2000 Feb, 56 ( Pt 2), 222 - 5
The purification, crystallization and structural elucidation of dTDP-D-glucose 4,6-dehydratase (RmlB), the second enzyme of the dTDP-L-rhamnose synthesis pathway from Salmonella enterica serovar typhimurium; Allard ST et al.; dTDP-D-glucose 4,6-dehydratase (RmlB) is the second of four enzymes involved in the dTDP-L-rhamnose pathway and catalyzes the dehydration of dTDP-D-glucose to dTDP-4-keto-6-deoxy-D-glucose . The ultimate product of the pathway, dTDP-L-rhamnose, is the precursor of L-rhamnose, which is a key component of the cell wall of many pathogenic bacteria . RmlB from Salmonella enterica serovar Typhimurium has been overexpressed and purified, and crystals of the enzyme have been grown using the sitting-drop vapour-diffusion technique with lithium sulfate as precipitant . Diffraction data have been obtained to a resolution of 2.8 A on a single frozen RmlB crystal which belongs to space group P2(1), with unit-cell parameters a = 111.85, b = 87.77, c = 145.66 A, beta = 131.53 degrees . The asymmetric unit contains four monomers in the form of two RmlB dimers with a solvent content of 62% . A molecular-replacement solution has been obtained and the model is currently being refined.

Acta Crystallogr D Biol Crystallogr, 1999 Dec, 55 ( Pt 12), 2043 - 6
Overexpression, purification, crystallization and preliminary structural study of dTDP-6-deoxy-L-lyxo-4-hexulose reductase (RmlD), the fourth enzyme of the dTDP-L-rhamnose synthesis pathway, from Salmonella enterica serovar Typhimurium; Giraud MF et al.; L-Rhamnose is an essential component of the cell wall of many pathogenic bacteria . Its precursor, dTDP-L-rhamnose, is synthesized from alpha-D-glucose-1-phosphate and dTTP via a pathway requiring four distinct enzymes: RmlA, RmlB, RmlC and RmlD . RmlD catalyses the terminal step of this pathway by converting dTDP-6-deoxy-L-lyxo-4-hexulose to dTDP-L-rhamnose . RmlD from -Salmonella enterica serovar Typhimurium has been overexpressed in Escherichia coli . The recombinant protein was purified by a two--step protocol involving anion-exchange and hydrophobic chromatography . Dynamic light-scattering experiments indicated that the recombinant protein is monodisperse . Crystals of native and selenomethionine-enriched RmlD have been obtained using the sitting-drop vapour-diffusion method with polyethylene glycol as precipitant . Diffraction data have been collected from orthorhombic crystals of both native and selenomethionyl-derivatized protein, allowing tracing of the protein structure.

Int J Clin Pract, 1999 Apr-May, 53(3), 161 - 4
Predictors for extraintestinal infection of non-typhoidal Salmonella in patients without AIDS; Chiu CH et al.; To identify the risks and predictors for extraintestinal infection (EII) in patients with non-typhoidal salmonellosis, we undertook a study of 398 patients with cultures positive for non-typhoidal Salmonella seen at Chang Gung Memorial Hospital and Chang Gung Children's Hospital between November 1993 and October 1994 . Salmonella choleraesuis was the most invasive serotype observed . S . panama, S . typhimurium and S . schwarzengrund were the commonest causes of EII among those serotypes usually causing gastroenteritis . Pre-existing underlying disease, particularly immunosuppressive disease, was the most important risk factor that may have predisposed adult patients to have EII . Old age (> or = 60 years) and isolation of invasive serotypes were also frequently associated with EII in adult patients . The characteristics of paediatric patients with a high probability of having EII were: < 3 years of age, abnormal blood test results (a leucocyte count > or = 15,000/mm3 or < 5000/mm3, immature leucocytes > or = 10% of total leucocytes, and a C-reactive protein concentration > or = 50 mg/l); and isolation of invasive serotypes . This information can be an aid to early diagnosis and treatment of EII caused by non-typhoidal Salmonella.

Cell, 2000 Jan 21, 100(2), 265 - 76
E . coli hemolysin E (HlyE, ClyA, SheA): X-ray crystal structure of the toxin and observation of membrane pores by electron microscopy; Wallace AJ et al.; Hemolysin E (HlyE) is a novel pore-forming toxin of Escherichia coli, Salmonella typhi, and Shigella flexneri . Here we report the X-ray crystal structure of the water-soluble form of E . coli HlyE at 2.0 A resolution and the visualization of the lipid-associated form of the toxin in projection at low resolution by electron microscopy . The crystal structure reveals HlyE to be the first member of a new family of toxin structures, consisting of an elaborated helical bundle some 100 A long . The electron micrographs show how HlyE oligomerizes in the presence of lipid to form transmembrane pores . Taken together, the data from these two structural techniques allow us to propose a simple model for the structure of the pore and for membrane interaction.

Adv Exp Med Biol, 1999, 473, 299 - 307
Prophylactic administration of immune lymphokine derived from T cells of Salmonella enteritidis-immune pigs . Protection against Salmonella choleraesuis organ invasion and cecal colonization in weaned pigs; Genovese KJ et al.; Experiments involving 132 weaned piglets were conducted to evaluate the efficacy of a Salmonella enteritidis-immune lymphokine (PILK) derived from the T cells of Salmonella enteritidis (SE)-immunized pigs to protect weaned piglets from Salmonella choleraesuis (SC) infection . Fourteen-to-seventeen day-old piglets were weaned and randomly placed into 1 of 5 groups: (1) noninfected controls, (2) PILK 3X noninfected, (3) SC infected controls, (4) PILK 1X SC infected, and (5) PILK 3X SC infected . PILK was given orally either one time (PILK 1X) or three times (PILK 3X) over 14 days . One hour after the first PILK administration on day 0, piglets were orally challenged with 10(7) cfu of SC . Weights were recorded on day 0, day 7, and day 14 . On day 14, pigs in groups 3, 4, and 5 were sacrificed and organs and lymph tissue were cultured for the presence of SC . Three replicates of this experiment were pooled and anlayzed . A significant reduction in the number of pigs positive for SC in the liver, lung, and spleen was found in group 5 (PILK 3X) when compared to group 3 (inf . cont . p < 0.001{) . The number of SC positive cecal contents was dramatically reduced in group 5 group when compared to group 3, with the PILK 3X group showing 13% positive pigs versus 55.2% in the infected controls (p < 0.05) . Weight gain over the 14 day study in the infected PILK 3X group (group 5) was found to be comparable to the gain observed in the group 1 (noninfected controls) . The pigs receiving PILK 3X (group 2) with no SC challenge gained significantly more weight than all other groups, including the noninfected controls (group 1 p < 0.05{) . The results of these experiments indicate that PILK protects against SC infection in weaned pigs while enhancing performance in the presence of an SC infection.

Adv Exp Med Biol, 1999, 473, 291 - 7
A preliminary survey of antibiotic resistance of Salmonella in market-age swine; Farrington LA et al.; We conducted an epidemiological survey of antibiotic resistance in Salmonella recovered from market-age swine at five different Texas farms . These farms, which were visited between October 1997 and June 1998, were completely integrated, farrow-to-finish operations . Samples were taken from the lymph nodes and cecal contents at the time of slaughter . The Salmonella samples that were recovered were sent to the National Veterinary Services Laboratory for serotyping . Antibiotic resistance was determined using the Dispens-O-Disc Susceptibility Test System using 13 different antimicrobial agents that have been utilized in either veterinary medicine, human medicine, or both . Preliminary analysis of the first 183 samples out of approximately 400 Salmonella samples recovered indicated that 183 (100%) of the Salmonella samples were resistant to penicillin G, and 122 (66.7%) were resistent to chlortetracycline . Six (3.3%) were resistant to four antibiotics (chlortetracycline, penicillin G, streptomycin, and sulfisoxazole), and 25 (13.7%) were resistant to three antibiotics (chlortetracycline, penicillin G, and either streptomycin, sulfisoxazole, or ampicillin) . Variation was seen between serotypes, with four out of five S . agona samples (80.0%) and two out of eight S . derby samples (25.0%) resistant to four antibiotics . Variation in antibiotic resistance also was seen between farms . There is an increasing concern about the prevalent usage of antibiotics in medicine and agriculture and the relationship this may have on emerging microbial resistance patterns; therefore, continued surveillance on antibiotic resistance in animal production is warranted.

Adv Exp Med Biol, 1999, 473, 275 - 80
Sips, Sops, and SPIs but not stn influence Salmonella enteropathogenesis; Wallis TS et al.; The virulence factors influencing Salmonella-induced enteropathogenesis remain poorly characterised . The interactions of different serotypes of Salmonella with bovine ileal mucosa have been characterised in the ligated ileal loop model . In a quantitative intestinal invasion assay Salmonella dublin, S . choleraesuis, S . gallinarum, and S . abortusovis strains were all recovered from ileal mucosa, either with or without Peyer's patches in similar numbers . This observation suggests that the magnitude and route of intestinal invasion does not mediate Salmonella serotype host specificity . Despite being equally invasive there was a clear hierarchy in the enteropathogenicity of these serotypes . The magnitude of the enteropathogenic responses did not correlate to serotype host specificity . These observations implicate undefined serotype specific factors in influencing enteropathogenicity independently of intestinal invasion . Disruption of genes in Salmonella Pathogenicity Island (SPI) 1 of S . typhimurium and S . dublin blocked the secretion of Salmonella Invasion Proteins (Sips) and Salmonella Outer Proteins (Sops) . These mutants were significantly less invasive and enteropathogenic then the wild type strain in ligated ileal loops . Disruption of sopB and sopD significantly reduced enteropathogenesis, but without influencing intestinal invasion . These two genes appear to act in concert . Surprisingly, disruption of stn, the Salmonella enterotoxin gene cloned on the basis of its homology to cholera toxin, did not influence enteropathogenesis . SopB was mapped to the 20 centisome of S . typhimurium and is flanked by 5 genes that are organised in a manner typical of a pathogenicity island, which we have termed SPI-5 . Mutation of the other genes in SPI-5 also attenuated enteropathogenesis but not virulence for mice, suggesting SPI-5 is a key locus specifically influencing Salmonella enteropathogenesis.

Adv Exp Med Biol, 1999, 473, 249 - 60
Norepinephrine stimulates in vitro growth but does not increase pathogenicity of Salmonella choleraesuis in an in vivo model; Nietfeld JC et al.; Norepinephrine stimulates growth of Escherichia coli, Yersinia enterocolitica, and Pseudomonas aeruginosa in serum-supplemented media, and in vivo increases in norepinephrine may be important in the pathogenesis of sepsis by gram-negative bacteria . Because salmonellosis often is associated with stress, the effects of norepinephrine on in vitro growth, and in vivo pathogenicity of the swine pathogen Salmonella choleraesuis were investigated . When RPMI 1640 with and without pig serum was inoculated with fewer than 100 S . choleraesuis/ml and incubated overnight, bacterial numbers were 10(4) to 10(6) lower in RPMI containing serum . Norepinephrine restored bacterial growth in RPMI with serum to normal levels, but it did not increase growth in serum-free RPMI . Similar results were obtained with SAPI, a nutrient-poor medium previously used to study the effect of norepinephrine on growth of gram-negative bacteria . Conditioned media were produced by growing S . choleraesuis in RPMI containing serum with and without norepinephrine and filter sterilizing . Conditioned medium produced with norepinephrine stimulated growth of S . choleraesuis but not E . coli, whereas conditioned medium produced without norepinephrine stimulated growth of both bacteria . To determine the in vivo effects of norepinephrine, rats were implanted with tablets that secrete norepinephrine for 20 to 24 hours or with identical tablets without norepinephrine and infected intraperitoneally with graded doses of S . choleraesuis . The LD-50 of S . choleraesuis was the same in both groups, and norepinephrine did not affect the carrier rate at 30 days after infection . We concluded that although norepinephrine stimulates in vitro growth of S . choleraesuis in serum-based media, the increase in norepinephrine levels in the present in vivo system was probably not sufficient to influence the pathogenesis of S . choleraesuis infection.

Mutat Res, 1999 Dec 16, 431(1), 81 - 91
Chemical carcinogenicity: can it be predicted from knowledge of mutagenicity and allergic contact dermatitis?
Rosenkranz HS, Karol MH.
We investigated the suggestion {R.E . Albert, Environ . Health Perspect . 105 (1997) 940-948.} that results of mutagenicity testing in Salmonella combined with allergic contact dermatitis (ACD) testing in humans would be predictive of carcinogenicity in rodents . Using the cancer bioassay results of the US National Toxicology Program (NTP), Salmonella mutagenicity tests and a highly predictive structure-activity relational model of ACD, we conclude that the combination is not more predictive than the results of the Salmonella mutagenicity assay alone.

Mutat Res, 1999 Dec 16, 431(1), 31 - 8
SOS chromotest and mutagenicity in Salmonella: evidence for mechanistic differences; Rosenkranz HS et al.; An examination of the relationship of the experimental results obtained with chemicals tested in the SOS chromotest and for mutagenicity in Salmonella indicates that the two assays respond to different genotoxic stimuli . Furthermore, the relationship between results obtained in these assays and in rodents carcinogenicity bioassays suggests that the short-term assays respond to a different spectrum of carcinogens . The same conclusions were reached based upon an analysis of the structural features associated with these three phenomena . With respect to using these short-term assays to predict carcinogens, the present results suggest that they are not equivalent, but complement one another.

Mutat Res, 1999 Dec 16, 431(1), 3 - 12
A new approach to risk estimation of food-borne carcinogens--heterocyclic amines--based on molecular information; Nagao M; Identification of causative agents for human cancers is the goal of our studies . We analyzed ordinary foods for mutagenicity, using the well-established Salmonella test . Heating fish and meat yielded mutagens that require metabolic activation for exhibition of mutagenicity . Structural determination revealed these mutagens to be heterocyclic amines (HCAs), their precursors in some cases being creatin(in)e, sugars and amino acids . Ten HCAs so far examined have all proved carcinogenic in mice and rats, inducing cancers in various organs such as in the mammary glands, prostate, lung, colon, skin, bladder and liver . Human exposure to HCAs is 0.1-12 microg/day, predominantly to 2-amino-1-methyl-6-phenyl-imidazo{4,5-b}pyridine (PhIP) and 2-amino-3,8-dimethylimidazo{4,5-f}quinoxaline (MeIQx) . For these types of genotoxic carcinogens, DNA-adduct formation is crucially important and PhIP-DNA adducts have been detected in human tissues . However, the amounts of individual HCAs ingested by humans may not be sufficient to induce cancers by themselves and many environmental factors have also been implicated in neoplasia in man, with other considerable inter-individual variation in susceptibility, e.g., to colon carcinogenesis . This is in line with results obtained by feeding different strains of rats with HCA . Studies using lacI transgenic mice and rats have revealed that DNA adducts do not directly correlate with mutant frequencies at the organ level, or cancer incidence . However, sequencing of the Apc gene of rat colon tumors induced by PhIP revealed that it induces a signature mutation of G deletion from the GGGA sequence . This type of mutation is found in the p53 gene of 0.3% human cancers having p53-somatic mutations, and it has been calculated that 3%-10% of the p53 mutations detected in human cancers could be ascribable to PhIP . Although there remains the possibility that other carcinogens involved in human carcinogenesis cause the same signature mutation, the available data point to an important role for PhIP.

Infect Control Hosp Epidemiol, 2000 Jan, 21(1), 33 - 8
Antimicrobial activity of home disinfectants and natural products against potential human pathogens; Rutala WA et al.; OBJECTIVE: To assess the efficacy of both natural products (vinegar, baking soda) and common commercial disinfectants (Vesphene IIse, TBQ, Clorox, Lysol Disinfectant Spray, Lysol Antibacterial Kitchen Cleaner, Mr . Clean Ultra, ethanol) designed for home or institutional use against potential human pathogens, including selected antibiotic-resistant bacteria . DESIGN: A quantitative suspension test was used to assess the efficacy of selected disinfectants following exposure times of 30 seconds and 5 minutes . Activity was assessed against Staphylococcus aureus, Salmonella choleraesuis, Escherichia coli O157:H7, and Pseudomonas aeruginosa . Selected disinfectants were also tested against poliovirus, vancomycin-susceptible and -resistant Enterococcus species, and methicillin-susceptible and -resistant S . aureus . RESULTS: The following compounds demonstrated excellent antimicrobial activity (>5.6-8.2 log10 reduction) at both exposure times: TBQ, Vesphene, Clorox, ethanol, and Lysol Antibacterial Kitchen Cleaner . Mr . Clean eliminated 4 to >6 logs10 and Lysol Disinfectant approximately 4 logs10 of pathogenic microorganisms at both exposure times . Vinegar eliminated <3 logs10 of S . aureus and E . coli, and baking soda <3 logs10 of all test pathogens . All tested chemical disinfectants completely inactivated both antibiotic-resistant and -susceptible bacteria at both exposure times . Only two disinfectants, Clorox and Lysol, demonstrated excellent activity (>3 log10 reduction) against poliovirus . CONCLUSIONS: A variety of commercial household disinfectants were highly effective against potential bacterial pathogens . The natural products were less effective than commercial household disinfectants . Only Clorox and Lysol disinfectant were effective against poliovirus.

Kansenshogaku Zasshi, 1999 Dec, 73(12), 1210 - 6
{Incidence of Salmonella serovar Hadar from sporadic cases in Tokyo, and drug resistance of isolates}; Matsushita S et al.; A total of 780 Salmonella serovar Hadar (S . Hadar) strains consisting of 601 domestic strains and 179 imported strains isolated in Tokyo, 1980-1998, were examined regarding their incidence and drug-resistance . Domestic strains accounted for 7.2% of all Salmonella (8,359 strains) isolated from domestic cases, and imported strains accounted for 4.4% of all Salmonella (4,083 strains) isolated from imported cases . A drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOR, and NFLX) showed that 586 strains (97.6%) of the domestic strains and 175 strains (97.8%) of the imported strains were resistant to some of the drugs, excluding NFLX . Drugs with a high resistance rate were TC and SM for both groups . Drug-resistance patterns of the resistant strains varied among the 24 types . Among those, prevalent patterns recognized were TC.SM.KM (231 strains), TC.SM (205 strains), and TC.SM.KM.ABPC (65 strains) in the domestic strains, and TC.SM (135 strains) and TC (13 strains) in the imported strains.

Proc Natl Acad Sci U S A, 2000 Feb 1, 97(3), 1258 - 62
A role for Salmonella fimbriae in intraperitoneal infections; Edwards RA et al.; Enteric bacteria possess multiple fimbriae, many of which play critical roles in attachment to epithelial cell surfaces . SEF14 fimbriae are only found in Salmonella enterica serovar Enteritidis (S . enteritidis) and closely related serovars, suggesting that SEF14 fimbriae may affect serovar-specific virulence traits . Despite evidence that SEF14 fimbriae are expressed by S . enteritidis in vivo, previous studies showed that SEF14 fimbriae do not mediate adhesion to the intestinal epithelium . Therefore, we tested whether SEF14 fimbriae are required for virulence at a stage in infection after the bacteria have passed the intestinal barrier . Polar mutations that disrupt the entire sef operon decreased virulence in mice more than 1,000-fold . Nonpolar mutations that disrupted sefA (encoding the major structural subunit) did not affect virulence, but mutations that disrupted sefD (encoding the putative adhesion subunit) resulted in a severe virulence defect . The results indicate that the putative SEF14 adhesion subunit is specifically required for a stage of the infection subsequent to transit across the intestinal barrier . Therefore, we tested whether SefD is required for uptake or survival in macrophages . The majority of wild-type bacteria were detected inside macrophages soon after i.p . infection, but the sefD mutants were not readily internalized by peritoneal macrophages . These results indicate that the potential SEF14 adhesion subunit is essential for efficient uptake or survival of S . enteritidis in macrophages . This report describes a role of fimbriae in intracellular infection, and indicates that fimbriae may be required for systemic infections at stages beyond the initial colonization of host epithelial surfaces.

J Clin Microbiol, 2000 Feb, 38(2), 895 - 7
Epidemic typhoid in vietnam: molecular typing of multiple-antibiotic-resistant Salmonella enterica serotype typhi from four outbreaks; Connerton P et al.; Multidrug-resistant Salmonella enterica serotype Typhi isolates from four outbreaks of typhoid fever in southern Vietnam between 1993 and 1997 were compared . Pulsed-field gel electrophoresis, bacteriophage and plasmid typing, and antibiotic susceptibilities showed that independent outbreaks of multidrug-resistant typhoid fever in southern Vietnam are caused by single bacterial strains . However, different outbreaks do not derive from the clonal expansion of a single multidrug-resistant serotype Typhi strain.

Nat Med, 2000 Feb, 6(2), 215 - 8
Molecular mimicry mediated by MHC class Ib molecules after infection with gram-negative pathogens; Lo WF et al.; The development of many autoimmune diseases has been etiologically linked to exposure to infectious agents . For example, a subset of patients with a history of Salmonella infection develop reactive arthritis . The persistence of bacterial antigen in arthritic tissue and the isolation of Salmonella or Yersinia reactive CD8+ T cells from the joints of patients with reactive arthritis support the etiological link between Gram-negative bacterial infection and autoimmune disease . Models proposed to account for the link between infection and autoimmunity include inflammation-induced presentation of cryptic self-epitopes, antigen persistence and molecular mimicry . Several studies support molecular mimicry as a mechanism for the involvement of class II epitopes in infectious disease-induced self-reactivity . Here, we have identified an immunodominant epitope derived from the S . typhimurium GroEL molecule . This epitope is presented by the mouse H2-T23-encoded class Ib molecule Qa-1 and was recognized by CD8+ cytotoxic T lymphocytes induced after natural infection . S . typhimurium-stimulated cytotoxic T lymphocytes recognizing the GroEL epitope cross-reacted with a peptide derived from mouse heat shock protein 60 and recognized stressed macrophages . Our results indicate involvement of MHC class Ib molecules in infection-induced autoimmune recognition and indicate a mechanism for the etiological link between Gram-negative bacterial infection and autoimmunity.

Appl Environ Microbiol, 2000 Feb, 66(2), 599 - 605
Genetically modified Vibrio harveyi strains as potential bioindicators of mutagenic pollution of marine environments; Czyz A et al.; For biodetection of mutagenic pollution of marine environments, an organism naturally occurring in these habitats should be used . We found that marine bacterium Vibrio harveyi may be an appropriate bioindicator of mutagenic pollution . For positive selection of mutants, we developed a simple method for isolation of V . harveyi mutants resistant to neomycin . We constructed genetically modified V . harveyi strains that produce significantly more neomycin-resistant mutants upon treatment with low concentrations of mutagens than the wild-type counterpart . The sensitivity of the mutagenicity test with the V . harveyi strains is at least comparable to (if not higher than) that of the commonly used Ames test, which uses Salmonella enterica serovar Typhimurium strains . Therefore, we consider that the V . harveyi strains described in this report could be used as potential bioindicators of mutagenic pollution of marine environments.

Emerg Infect Dis, 2000 Jan-Feb, 6(1), 60 - 4
Molecular typing of multidrug-resistant Salmonella Blockley outbreak isolates from Greece; Tassios PT et al.; During 1998, a marked increase (35 cases) in human gastroenteritis due to Salmonella Blockley, a serotype rarely isolated from humans in the Western Hemisphere, was noted in Greece . The two dominant multidrug-resistance phenotypes (23 of the 29 isolates studied) were associated with two distinct DNA fingerprints, obtained by pulsed-field gel electrophoresis of genomic DNA.

Genes Genet Syst, 1999 Aug, 74(4), 179 - 83
Promoter analysis of the class 2 flagellar operons of Salmonella; Ikebe T et al.; The Salmonella flagellar operons are divided into three classes with reference to their relative positions in the transcriptional hierarchy . Expression of the class 2 operons requires the class 1 gene products, FlhD and FlhC, and is enhanced by an unknown mechanism in the presence of the class 3-specific sigma factor, FliA, and in the absence of its cognate anti-sigma factor, FlgM . In this study, the transcriptional start site mapping was performed by primer extension analysis for five class 2 operons, flgA, flgB, flhB, fliE and fliL . In all cases, one or a few major transcriptional start sites were identified . These start signals disappeared in the flhDC-mutant background, and their intensity decreased and increased in the fliA-mutant and flgM-mutant backgrounds, respectively . Therefore, we conclude that the FlhD/FlhC-dependent transcription is responsible for the FliA-dependent enhancement . Sequence comparison revealed that an imperfect inverted repetitious sequence is conserved upstream of the class 2 operons . Truncation of this sequence from the flgB promoter reduced its transcriptional activity to the background level, indicating that this is an essential cis-acting element for transcription of the class 2 operons.

J Bacteriol, 2000 Feb, 182(4), 1035 - 45
Insertional inactivation of genes encoding components of the sodium-type flagellar motor and switch of Vibrio parahaemolyticus; Boles BR et al.; Vibrio parahaemolyticus possesses two types of flagella, polar and lateral, powered by distinct energy sources, which are derived from the sodium and proton motive forces, respectively . Although proton-powered flagella in Escherichia coli and Salmonella enterica serovar Typhimurium have been extensively studied, the mechanism of torque generation is still not understood . Molecular knowledge of the structure of the sodium-driven motor is only now being developed . In this work, we identify the switch components, FliG, FliM, and FliN, of the sodium-type motor . This brings the total number of genes identified as pertinent to polar motor function to seven . Both FliM and FliN possess charged domains not found in proton-type homologs; however, they can interact with the proton-type motor of E . coli to a limited extent . Residues known to be critical for torque generation in the proton-type motor are conserved in the sodium-type motor, suggesting a common mechanism for energy transfer at the rotor-stator interface regardless of the driving force powering rotation . Mutants representing a complete panel of insertionally inactivated switch and motor genes were constructed . All of these mutants were defective in sodium-driven swimming motility . Alkaline phosphatase could be fused to the C termini of MotB and MotY without abolishing motility, whereas deletion of the unusual, highly charged C-terminal domain of FliM disrupted motor function . All of the mutants retained proton-driven, lateral motility over surfaces . Thus, although central chemotaxis genes are shared by the polar and lateral systems, genes encoding the switch components, as well as the motor genes, are distinct for each motility system.

J Bacteriol, 2000 Feb, 182(4), 905 - 10
prpR, ntrA, and ihf functions are required for expression of the prpBCDE operon, encoding enzymes that catabolize propionate in Salmonella enterica serovar typhimurium LT2; Palacios S et al.; The genes required for the catabolism of propionate in Salmonella enterica serovar Typhimurium are organized as two transcriptional units (prpR and prpBCDE) that are divergently transcribed from one another . Sequence homology to genes encoding members of the sigma-54 family of transcriptional activators and the identification of a consensus sigma-54 promoter 5' to the prpBCDE operon suggested that PrpR was required to activate expression of this operon . We isolated insertions in prpR and showed that prpR function was needed for growth on propionate as a carbon and energy source . A medium-copy-number plasmid carrying the lacZ gene under the control of the native sigma-54 promoter of prpBCDE was used to study prpBCDE operon expression . Transcription of the lacZ reporter in prpR, ntrA, and ihfB mutants was 85-, 83-, and 15-fold lower than the level of transcription measured in strains carrying the wild-type allele of the gene tested . These data indicated that PrpR, IHF, and transcription sigma factor RpoN were required for the expression of the prpBCDE operon . Further analysis of the involvement of the integration host factor (IHF) protein in the expression of this operon is required due to the well-documented pleiotropic effect the lack of this global regulator has on gene expression . Deletion of the 5' 615-bp portion of the prpR gene resulted in a PrpR(c) mutant protein that activated prpBCDE transcription regardless of the ability of the strain to synthesize 2-methylcitrate, the putative coactivator of PrpR . These results indicate that the N terminus of PrpR is the coactivator-sensing domain of the protein . When placed under the control of the arabinose-inducible promoter P(araBAD), expression of prpR(c) allele by arabinose had a strong negative effect on growth of the cell . It is proposed that this deleterious effect of PrpR(c) may be due to an uncontrolled ATPase activity of PrpR or to cross-activation of genes whose functions negatively affect cell growth under the conditions tested.

J Bacteriol, 2000 Feb, 182(4), 869 - 73
Genetic and biochemical characterization of Salmonella enterica serovar typhi deoxyribokinase; Tourneux L et al.; We identified in the genome of Salmonella enterica serovar Typhi the gene encoding deoxyribokinase, deoK . Two other genes, vicinal to deoK, were determined to encode the putative deoxyribose transporter (deoP) and a repressor protein (deoQ) . This locus, located between the uhpA and ilvN genes, is absent in Escherichia coli . The deoK gene inserted on a plasmid provides a selectable marker in E . coli for growth on deoxyribose-containing medium . Deoxyribokinase is a 306-amino-acid protein which exhibits about 35% identity with ribokinase from serovar Typhi, S . enterica serovar Typhimurium, or E . coli . The catalytic properties of the recombinant deoxyribokinase overproduced in E . coli correspond to those previously described for the enzyme isolated from serovar Typhimurium . From a sequence comparison between serovar Typhi deoxyribokinase and E . coli ribokinase, whose crystal structure was recently solved, we deduced that a key residue differentiating ribose and deoxyribose is Met10, which in ribokinase is replaced by Asn14 . Replacement by site-directed mutagenesis of Met10 with Asn decreased the V(max) of deoxyribokinase by a factor of 2.5 and increased the K(m) for deoxyribose by a factor of 70, compared to the parent enzyme.

J Microbiol Immunol Infect, 1999 Dec, 32(4), 289 - 91
Non-typhoid Salmonella subdural empyema in children: report of two cases; Yen MH et al.; Subdural empyema caused by Salmonella in childhood is an uncommon condition . The predisposing factors for this condition are not clearly established, especially in young children . Here we present two cases of subdural empyema caused by non-typhoidal Salmonella . Both of the patients suffered prolonged fever without local signs of infection on admission . Subdural empyema was subsequently detected by brain echo and brain computerized tomography (CT) scan in both cases . Cerebrospinal fluid (CSF) study was not done in case one due to prominent mass effect on brain CT; in case two the CSF analysis showed pleocytosis, but CSF bacterial culture was negative . Neither enteritis nor obvious meningeal sign was noted . Both cases responded well to surgical drainage and systemic antibiotics treatment.

J Microbiol Immunol Infect, 1999 Dec, 32(4), 261 - 8
Pyogenic psoas abscess: analysis of 27 cases; Lin MF et al.; From 1993 to 1998, 29 pyogenic psoas abscesses occurring in 27 patients were seen in Taichung Veterans General Hospital . Their age range was 25 to 85 years . Diabetes mellitus was the leading underlying disease . Fever and pain in the flank area, back and hip were the usual manifestations . The duration of symptoms prior to the diagnosis ranged from 3 days to 6 months . Most abscesses were diagnosed by computed tomography (CT) images and proven by abscess cultures, which were divided into primary and secondary types . Eighteen of 29 abscesses were regarded as primary . Staphylococcus aureus was the most common pathogen in the primary abscesses, followed by Streptococcus agalactiae, Escherichia coli, viridans streptococci, S . epidermidis, and Salmonella spp. . In the secondary abscess category, E . coli was the leading organism in this series, followed by S . aureus, Klebsiella pneumoniae, viridans streptococci and Candida albicans . The associated conditions included epidural abscess, osteomyelitis, septic arthritis, perirenal abscess, pulmonary tuberculosis, empyema, hydronephrosis and trauma history . The initial empiric therapy comprised mostly of cefazolin or oxacillin with or without an aminoglycoside . Thirteen patients underwent percutaneous drainage, while six received surgical debridement, including two with a recurrent abscess . One patient had both drainage and debridement . Others received medical treatment only . Two of the patients with primary abscess died in spite of percutaneous drainage . Therefore, open drainage, besides appropriate antibiotic treatment, is still required to control complex abscesses with sepsis.

Can Vet J, 1999 Dec, 40(12), 871 - 7
{Control measures for contagious enteric diseases in a veterinary teaching hospital}; Ravary B et al.; Instructions and control measures related to enteric contagious diseases at the Veterinary Medical Teaching Hospital (VMTH) of the Faculty of Veterinary Medicine of the University of Montreal are presented . These control measures, which have given satisfactory results within the past decade, are exemplified by a salmonellosis outbreak that occurred in spring 1996 in the large animal clinic of the VMTH . Emphasis was put on the importance of antigenic and/or genetic characterizations of Salmonella isolates, in order to detect an eventual source of contamination, but also to determine the incidence of nosocomial infections among hospitalized animals.

Postgrad Med J, 1999 Aug, 75(886), 479 - 80
A patient with fever and an abdominal aortic aneurysm; Barlow GD et al.; A 55-year-old man with an abdominal aortic aneurysm presented with fever and abdominal pain 3 weeks after an episode of Salmonella gastroenteritis . His symptoms persisted despite antimicrobial therapy . Two abdominal computed tomography (CT) scans showed no evidence of aortitis . His abdominal pain worsened and further investigation including a third CT scan demonstrated a leaking aortic aneurysm . The wall of the aorta was shown to contain Gram-negative bacilli . This case illustrates the difficulty in diagnosing bacterial aortitis.

Microb Pathog, 2000 Feb, 28(2), 59 - 70
The Salmonella YopJ-homologue AvrA does not possess YopJ-like activity; Schesser K et al.; The YopJ protein of Yersinia pseudotuberculosis inhibits several eukaryotic signalling pathways that are normally activated in cells following their contact with bacteria . Salmonella encodes a protein, AvrA, that is secreted by the typeIII inv/spa secretion system which is clearly homologous to YopJ (56% identical, 87% similarity) . Since AvrA and YopJs similarity also encompassed a region of YopJ that had previously been shown to be critical for its biological activity, we were interested whether AvrA and YopJ provoked similar responses in eukaryotic cells . Two different approaches were used to determine whether AvrA possesses YopJ-like activity in modulating cytokine expression or killing macrophages . An avrA strain of Salmonella dublin was constructed and its activity was compared to an isogenic wildtype counterpart in cellular response assays . In a complementary approach, AvrA was expressed in and delivered into eukaryotic cells by a yopJ strain of Yersinia pseudotuberculosis . We show here that AvrA affects neither cytokine expression or plays a role in macrophage killing when expressed by either Salmonella or Yersinia . Additionally, AvrA does not possess SopB/D-like activity in promoting fluid secretion into infected calf ileal loops . These data indicate that Salmonella and Yersinia trigger and/or modulate eukaryotic cell responses by different typeIII-secreted proteins and suggests that despite their close evolutionary relatedness, AvrA and YopJ perform different functions for Salmonella and Yersinia, respectively .

J Food Prot, 2000 Jan, 63(1), 36 - 43
Factors influencing inactivation of Salmonella enteritidis in hard-cooked eggs; Chantarapanont W et al.; The inside of a hen's egg, once considered sterile, is now known to occasionally harbor Salmonella Enteritidis . At least two recent outbreaks of salmonellosis in which Salmonella Enteritidis PT34 was involved have been associated with hard-cooked eggs . This study was undertaken to compare D56 degrees C values of Salmonella Senftenberg 775W and six strains of Salmonella Enteritidis isolated from outbreaks associated with eggs . D56 degrees C values for Salmonella Enteritidis in liquid egg yolk ranged from 5.14 to 7.39 min; the D56 degrees C value for Salmonella Senftenberg was 19.96 min . The two PT34 strains from outbreaks associated with hard-cooked eggs did not exhibit significantly higher resistance to heat compared with two PT4 strains and one strain each of PT8 and PT13a . A PT4 strain and a PT34 strain of Salmonella Enteritidis were separately inoculated (10(7) to 10(8) CFU) into the yolk of medium and extra large shell eggs at 10 and 21 degrees C, and survival was monitored using two cooking methods: (i) placing eggs in water at 23 degrees C, heating to 100 degrees C, removing from heat, and holding for 15 min (American Egg Board method) and (ii) placing eggs in water at 100 degrees C, then holding for 15 min at this temperature . Within the 15-min holding periods, inactivation was more rapid using the method recommended by the American Egg Board compared with method 2 . Within each cooking method, inactivation was most rapid in medium eggs initially at 21 degrees C . The PT4 strain survived in yolk of extra large eggs initially at 10 degrees C when eggs were held in boiling water 9 min using method 2 . The final temperature of the yolk in these eggs was 62.3 +/- 2 degrees C . Of the two methods evaluated for hard cooking eggs, the American Egg Board method is clearly most effective in killing Salmonella Enteritidis in the yolk.

J Food Prot, 2000 Jan, 63(1), 25 - 30
Bactericidal activity of isothiocyanate against pathogens on fresh produce; Lin CM et al.; The bactericidal activity of allyl and methyl isothiocyanate (AITC and MITC) was tested with a rifampicin-resistant strain of Salmonella Montevideo and streptomycin-resistant strains of Escherichia coil O157:H7 and Listeria monocytogenes Scott A . Iceberg lettuce inoculated with high (10(7) to 10(8) CFU/g) and low (10(3) to 10(4) CFU/g) concentrations of bacterial pathogens was treated with AITC and MITC in sealed containers at 4 degrees C for 4 days . AITC showed stronger bactericidal activity than MITC against E . coli O157:H7 and Salmonella Montevideo, whereas MITC showed stronger activity against L . monocytogenes than E . coli O157:H7 and Salmonella Montevideo . Up to 8-log reduction occurred with E . coli O157:H7 and Salmonella Montevideo on lettuce following treatment with vapor generated from 400 microl of AITC for 2 and 4 days, respectively . AITC was used to treat tomatoes inoculated with Salmonella Montevideo on stem scars and skin and apples inoculated with E . coli O157:H7 on stem scars . The bactericidal effect of AITC varied with bacteria species and exposure time . Salmonella Montevideo inoculated on tomato skin was more sensitive to AITC than that on stem scars . Treatment with vapor generated from 500 microl of AITC caused an 8-log reduction in bacteria on tomato skin but only a 5-log reduction on tomato stem scars . The bactericidal activity of AITC was weaker for E . coli O157:H7 on apple stem scars; only a 3-log reduction in bacteria occurred when 600 microl of AITC was used.

Unfallchirurg, 1999 Dec, 102(12), 967 - 71
{Bacterial coxitis caused by Salmonella enteritidis . Case report and differential diagnostic considerations}; Sarkar MR et al.; Secondary haematogenous joint involvement is seen in less than 1% of patients with Salmonella infections . These atypical infections are frequently encouraged by pre-existing local or systemic disease . We present a case of a patient with known alcohol abuse who developed a septic infection of her right hip requiring resection of the femoral head . Histologic analysis showed signs of pre-existing osteonecrosis probably induced by alcohol intake . Cartilage and bone were invaded and destructed by an aggressive granulation tissue . Initially, a biopsy evaluated without knowledge of the positive bacteriological result had been interpreted as indicative of a tumour . The onset, clinical course, diagnosis and therapy of joint involvement by Salmonella are discussed with regard to our case and the relevant literature . This case illustrates the necessity for clinicians to share all their information about the patient with the pathologist.

Can Vet J, 2000 Jan, 41(1), 54 - 9
Salmonellosis in songbirds in the Canadian Atlantic provinces during winter-summer 1997-98; Daoust PY et al.; From winter 1997 to summer 1998, an epizootic of salmonellosis affected several species of songbirds over a large area of the eastern North American continent . This article describes the details of this epizootic in the Canadian Atlantic provinces, based on laboratory examination of dead affected birds and on suspected but unconfirmed cases of salmonellosis reported by members of the public . The common redpoll (Carduelis flammea) was the species most often affected, followed by pine siskins (C . pinus), purple finches (Carpodacus purpureus), evening grosbeaks (Coccothraustes vespertinus), and American goldfinches (Carduelis tristis) . A poor body condition and necrotizing and fibrinopurulent esophagitis and ingluvitis were the most common gross lesions in these birds . Thirty-four of 35 isolates of Salmonella recovered from these birds were identified as phage type 40 . Despite the magnitude of this and previous epizootics of salmonellosis among North American songbirds, the sources of these epizootics and the precise influence of environmental factors on their occurrence remain poorly understood.

Infect Immun, 2000 Feb, 68(2), 986 - 9
Use of lambda phage S and R gene products in an inducible lysis system for Vibrio cholerae- and Salmonella enterica serovar typhimurium-based DNA vaccine delivery systems; Jain V et al.; Novel methods for adapting DNA vaccine technology to the prevention of mucosal diseases are greatly needed . Here we show that regulated expression of phage lambda lysis genes S and R causes dramatic lysis of both Vibrio cholerae and Salmonella enterica serovar Typhimurium cells with concomitant release of plasmid DNA into the surrounding media . We also used single and double DNase mutant strains to show that secreted V . cholerae DNases can adversely affect the integrity of DNA molecules released upon lysis . These results suggest that incorporation of lambda SR-mediated lysis constructs and DNA stabilizing mutations into candidate live attenuated bacterial vaccines offers a promising approach for the development of effective mucosal DNA delivery vectors for humans.

Infect Immun, 2000 Feb, 68(2), 861 - 70
Impact of heterogeneity within cultured cells on bacterial invasion: analysis of Pseudomonas aeruginosa and Salmonella enterica serovar typhi entry into MDCK cells by using a green fluorescent protein-labelled cystic fibrosis transmembrane conductance regulator receptor; Gerceker AA et al.; The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride ion channel that also serves as a receptor for entry of Pseudomonas aeruginosa and Salmonella enterica serovar Typhi into epithelial cells . To evaluate heterogeneity in CFTR protein expression in cultured cells and the effect of heterogeneity on internalization of different P . aeruginosa and serovar Typhi strains, we used two-color flow cytometry and confocal laser microscopy to study bacterial uptake by Madin-Darby canine kidney (MDCK) type I epithelial cells stably expressing a green fluorescent protein (GFP)-CFTR fusion construct (MDCK-GFP-CFTR cells) . We found a strong correlation between cell size and GFP-CFTR protein expression, with 60 to 70% of cells expressing low levels of GFP-CFTR protein, 20 to 30% expressing intermediate levels, and <10% expressing high levels . The cells were sorted into low-, intermediate-, or high-level producers of CFTR protein; in vitro growth of each sorted population yielded the same distribution of CFTR protein expression as that in the original population . Cells expressing either low or high levels of CFTR protein internalized bacteria poorly; maximal bacterial uptake occurred in the cells expressing intermediate levels of CFTR protein . Treatment of MDCK cells with sodium butyrate markedly enhanced the production of CFTR protein without increasing cell size; butyrate treatment also increased the proportion of cells with internalized bacteria . However, there were fewer bacteria per butyrate-treated cell and, for P . aeruginosa, there was an overall decrease in the total level of bacterial uptake . The most highly ingested bacterial strains were internalized by fewer total MDCK-GFP-CFTR cells, indicating preferential bacterial uptake by a minority of epithelial cells within a given culture . Confocal fluorescence microscopy showed that P . aeruginosa and serovar Typhi induced cytoplasmic accumulation of CFTR protein close to the plasma membrane where the bacteria were adherent . These results show that within a population of MDCK-GFP-CFTR cells, there are cells with markedly different abilities to ingest bacteria via CFTR, the majority of the P . aeruginosa and serovar Typhi cells are ingested by the one-fourth to one-third of the cells that exhibit an intermediate size and level of CFTR protein expression, and overexpression of the CFTR receptor does not increase total bacterial uptake but rather allows more epithelial cells to ingest fewer total bacteria.

Infect Immun, 2000 Feb, 68(2), 732 - 9
Expression and immunogenicity of hemagglutinin A from Porphyromonas gingivalis in an avirulent Salmonella enterica serovar typhimurium vaccine strain; Kozarov E et al.; Porphyromonas gingivalis is a major etiologic agent of periodontitis, a chronic inflammatory disease that ultimately results in the loss of the supporting tissues of the teeth . Previous work has demonstrated the usefulness of avirulent Salmonella enterica serovar Typhimurium strains as antigen delivery systems for protective antigens of pathogens that colonize or cross mucosal surfaces . In this study, we constructed and characterized a recombinant S . enterica serovar Typhimurium avirulent vaccine strain which expresses hemagglutinin A and carries no antibiotic resistance markers . HagA, a major virulence-associated surface protein, is a potentially useful immunogen that contains an antigenic epitope which, in humans, elicits an immune response that is protective against subsequent colonization by P . gingivalis . The hagA gene, including its promoter, was cloned into a balanced-lethal Salmonella vector and transferred to the vaccine strain . Heterologous expression of HagA was demonstrated in both Escherichia coli JM109 and S . enterica serovar Typhimurium vaccine strain chi4072 . The HagA epitope was present in its native configuration as determined by immunochemistry and immunoelectron microscopy . Purified recombinant HagA was recognized by sera from mice immunized with the S . enterica serovar Typhimurium vaccine strain . The HagA-specific antigen of the vaccine was also found to be recognized by serum from a periodontal patient . This vaccine strain, which expresses the functional hemagglutinin protein, induces a humoral immune response against HagA and may be useful for developing a protective vaccine against periodontal diseases associated with P . gingivalis.

Trends Microbiol, 2000 Jan, 8(1), 29 - 33
Phosphatases and kinases delivered to the host cell by bacterial pathogens; DeVinney I et al.; The gram-negative type III secretion pathway translocates bacterial proteins directly into eukaryotic host cells, thus allowing a pathogen to interfere directly with host signalling pathways . Protein and inositol phosphatases and protein kinases have been identified as delivered effectors in three bacterial pathogens, Salmonella, Shigella and Yersinia, and it is expected that several more such type III effectors will be found.

Antibiot Khimioter, 1999, 44(10), 13 - 5
{The immunotropic properties of the deoxyribonucleic acid from Salmonidae milt}; Besednova NN et al.; The study of the immunotropic action of DNA from salmon milt showed that it increased the antiinfectious resistance of mice to Escherichia coli and Salmonella enteritidis, stimulated the antibody response to the thymus-dependent corpuscular antigen (sheep erythrocytes), increased the production of the antibody forming cells (AFC) in the murine spleen and intensified the absorptive and digestive activities of the cells of the mononuclear phagocytes . The immunotropic properties of the DNA permitted to broaden the DNA application spectrum with its supplementing by immunodeficiency of various genesis and diseases with phagocytic protection mechanisms . It is quite possible that the salmon milt DNA be used as a food additive.

Mutat Res, 1999 Dec 13, 446(2), 167 - 74
Reduction in Ames Salmonella mutagenicity of mainstream cigarette smoke condensate by tobacco protein removal; Clapp WL et al.; The mutagenic activity of cigarette smoke condensates (CSC) made from tobacco before and after removal of protein was assessed by the Ames Salmonella assay in bacterial strains TA98 and TA100 . Removal of protein and peptides from flue-cured tobacco via water extraction followed by protease digestion reduced the mutagenicity of the resultant CSC by 80% in the TA98 strain and 50% in the TA100 strain . Similarly, reductions of 81% in TA98 and 54% in TA100 were seen following water extraction and protease digestion of burley tobacco . The significant reductions in Ames mutagenicity following protein removal suggest that protein pyrolysis products are a principal contributor to the genotoxicity of CSC as measured in this assay.

J Bacteriol, 2000 Feb, 182(3), 771 - 81
OmpR regulates the two-component system SsrA-ssrB in Salmonella pathogenicity island 2; Lee AK et al.; Salmonella pathogenicity island 2 (SPI-2) encodes a putative, two-component regulatory system, SsrA-SsrB, which regulates a type III secretion system needed for replication inside macrophages and systemic infection in mice . The sensor and regulator homologs, ssrAB (spiR), and genes within the secretion system, including the structural gene ssaH, are transcribed after Salmonella enters host cells . We have studied the transcriptional regulation of ssrAB and the secretion system by using gfp fusions to the ssrA and ssaH promoters . We found that early transcription of ssrA, after entry into macrophages, is most efficient in the presence of OmpR . An ompR mutant strain does not exhibit replication within cultured macrophages . Furthermore, footprint analysis shows that purified OmpR protein binds directly to the ssrA promoter region . We also show that minimal medium, pH 4.5, induces SPI-2 gene expression in wild-type but not ompR mutant strains . We conclude that the type III secretion system of SPI-2 is regulated by OmpR, which activates expression of ssrA soon after Salmonella enters the macrophage.

Burns, 1999 Dec, 25(8), 723 - 7
Salmonella senftenberg: a new pathogen in the burns ward; Nair D et al.; This is the first report of Salmonella senftenberg serovar outbreak in a burns unit . This unit admits about 2000 patients with major burn injuries annually . Routine sampling from wound swabs in December 1995 revealed S . senftenberg in a few samples following which a study was instituted from January to March 1996 . Of 446 burn admissions during this period 80 patients were culture positive for S . senftenberg in wound swabs . The protocol for investigation included wound swabs on admission and then at biweekly interval, blood culture studies on clinically toxic patients, anti-microbial sensitivity studies, environmental sampling and hand swabs and stool cultures from about 50 staff members of the burns ward . No wound swab at the time of admission was positive for S . senftenberg . Environmental study and the study of staff members did not reveal any obvious source of the infection . S . senftenberg strains were sensitive to more than seven of the 11 anti-microbials tested at the beginning of the study but later 96.3% of the strains showed multidrug (more than three drugs) resistance . By April 1996 the isolates became negligible and later disappeared completely . The organism resurfaced again in March 1997 and the same study was instituted again on 413 admissions between March and May 1997 . Fifty patients were culture positive for S . senftenberg . This time stool sample from one burn dresser tested positive for S . senftenberg . Interestingly, again at the beginning of the second outbreak the Salmonella strains were sensitive to 9 out of 11 anti-microbials tested, but later 96.11% strains became multidrug resistant . S . senftenberg strains showed maximum resistance to amoxycillin (97.5%) and minimum to chloramphenicol, tetracycline and cotrimoxazole (12%) . It was noticed that Salmonella strains surfaced in wound swabs after 3-4 weeks of hospital stay . Forty-five out of 130 patients studied, in both the episodes, died due to septicemia . The majority of the patients who died had sustained > 60% TBSA burns . Blood cultures were done in 34/130 patients and eight yielded growth (2 S . senftenberg, 4 Klebsiella spp., and two Pseudomonas spp.)

J Bacteriol, 2000 Jan, 182(2), 518 - 21
opdA, a Salmonella enterica serovar Typhimurium gene encoding a protease, is part of an operon regulated by heat shock; Conlin CA et al.; The opdA (prlC) gene of Salmonella enterica serovar Typhimurium and Escherichia coli encodes the metalloprotease oligopeptidase A (OpdA) . We report that opdA is cotranscribed with a downstream open reading frame, yhiQ . Transcription of this operon is induced after a temperature shift (30 to 42 degrees C), and this induction depends on the heat shock sigma factor encoded by the rpoH (htpR) gene.

J Bacteriol, 2000 Jan, 182(2), 513 - 7
The amino terminus of Salmonella enterica serovar Typhimurium sigma(54) is required for interactions with an enhancer-binding protein and binding to fork junction DNA; Kelly MT et al.; Transcription initiation by the sigma(54)-RNA polymerase holoenzyme requires an enhancer-binding protein that is thought to contact sigma(54) to activate transcription . To identify potential enhancer-binding protein contact sites in sigma(54), we compared the abilities of wild-type and truncated forms of Salmonella enterica serovar Typhimurium sigma(54) to interact with the enhancer-binding protein DctD in a chemical cross-linking assay . Removal of two regions in the amino-terminal portion of sigma(54), residues 57 to 105 and residues 144 to 179, prevented cross-linking, but removal of either region alone did not . In addition, deletion of 56 amino-terminal residues of sigma(54) (region I) reduced the affinity of the protein for a fork junction DNA probe.

J Food Prot, 2000 Dec, 63(12), 1749 - 53
Prevalence and dissemination of Salmonella serotypes along the slaughtering process in Brazilian small poultry slaughterhouses; Fuzihara TO et al.; Salmonella is the leading cause of human foodborne infections in Latin America, and poultry meat is one of the main vehicles . Small poultry slaughterhouses (fewer than 200 birds slaughtered per day) represent an important economic activity in certain regions . The slaughtering process in these abattoirs is manual and rudimentary, and frequently the hygienic conditions are poor . This study reports results of a detailed evaluation of the prevalence of Salmonella serotypes in carcasses, utensils, and environmental samples collected in 60 small Brazilian slaughterhouses . In the second step of the study, one of these slaughterhouses was selected to monitor the dissemination of Salmonella along the slaughtering process . For testing, conventional procedures were used: preenrichment in buffered peptone water (35 degrees C for 24 h), selective enrichment in Selenite-cystine (35 degrees C for 24 h), tetrathionate and Rappaport-Vassiliadis broths (42 degrees C for 24 h), plating on bismuth-sulfite and brilliant green agars (35 degrees C for 24 h), proper biochemical testing, and complete serotyping . Forty-one percent of samples harbored Salmonella spp., including 42% of carcasses, 23.1% of utensils, 71.4% of water, and 71.4% of freezers and refrigerators . Seventeen serotypes were detected . Salmonella Enteritidis predominated (30%), followed by Salmonella Albany (12%), Salmonella Hadar (12%), Salmonella Indiana (10%), and I 4,12:z:- (8%) . All samples collected along the slaughtering process in the selected slaughterhouse were Salmonella positive . Five serotypes were detected, including Salmonella Albany, Salmonella Hadar, Salmonella Agona, Salmonella Emek, and Salmonella Indiana . More than 30% of the samples contained more than one serotype, and 12.5% presented three serotypes . The widespread occurrence of Salmonella in small slaughterhouses reinforces the need for implementation of effective control measures.

J Food Prot, 2000 Dec, 63(12), 1676 - 80
Validation of acid washes as critical control points in hazard analysis and critical control point systems; Dormedy ES et al.; A 2% lactic acid wash used in a large meat-processing facility was validated as an effective critical control point (CCP) in a hazard analysis and critical control point (HACCP) plan . We examined the microbial profiles of beef carcasses before the acid wash, beef carcasses immediately after the acid wash, beef carcasses 24 h after the acid wash, beef subprimal cuts from the acid-washed carcasses, and on ground beef made from acid-washed carcasses . Total mesophilic, psychrotrophic, coliforms, generic Escherichia coli, lactic acid bacteria, pseudomonads, and acid-tolerant microorganisms were enumerated on all samples . The presence of Salmonella spp . was also determined . Acid washing significantly reduced all counts except for pseudomonads that were present at very low numbers before acid washing . All other counts continued to stay significantly lower (P < 0.05) than those on pre-acid-washed carcasses throughout all processing steps . Total bacteria, coliforms, and generic E . coli enumerated on ground beef samples were more than 1 log cycle lower than those reported in the U.S . Department of Agriculture Baseline data . This study suggests that acid washes may be effective CCPs in HACCP plans and can significantly reduce the total number of microorganisms present on the carcass and during further processing.

Rev Sci Tech, 2000 Dec, 19(3), 831 - 40
Macrophage recruitment and activation: a model for comparing resistance to Salmonella enteritidis in different broiler breeds; Barbour EK et al.; A model for comparing resistance to Salmonella Enteritidis was evaluated in different broiler breeds . The recruitment and phagocytic activity of peritoneal macrophages were assessed in three different broiler breeds (A, B and C) which are farmed world-wide . Assessment was performed after three days of intraperitoneal (i.p.) administration of 3% Sephadex G-200 (10 ml), initiated at twenty-one days of age, followed by contact with i.p . live S . Enteritidis (10 ml, 1.2 x 10(8) colony forming units/ml) for 45 min . Assessment included determination of the number of i.p . macrophages recruited, the number of i.p . phagocytized S . Enteritidis cells per macrophage, the levels of degranulated i.p . beta-glucuronidase and beta-galactosidase, and the count of surviving S . Enteritidis cells . Confirmation of the significance of the model was obtained by comparing resistance to field infection by S . Enteritidis in the three broiler breeds . The recruitment of i.p . macrophages in response to challenge with Sephadex and S . Enteritidis was significantly higher (P < 0.05) in birds of breed A (mean cumulative i.p . macrophage count, in 10 fields of microscopic slide smear magnified at x1,000, was equal to 81.7), compared to recruitment in birds of breed B (33.3) or breed C (41.2) . The mean number of phagocytized S . Enteritidis cells per i.p . macrophage in birds of breed A (2.68) was significantly higher (P < 0.05) than in breed B (0.83) and insignificantly higher (P > 0.05) than in breed C (2.35) . In addition, the highest level of recruitment and phagocytic activity of macrophages, in birds of breed A, was associated with a higher significant mean i.p . beta-glucuronidase activity (10,425.5 units/ml) than in breed B (3,438.2 units/ml) or breed C (3,356.94 units/ml) (P < 0.05) . Moreover, birds of breed A demonstrated a higher mean i.p . beta-galactosidase activity (2.225 units/ml) than birds of breed B (0.852 units/ml) or breed C (1.852 units/ml) (P > 0.05) . The higher level of recruitment and activity of i.p . macrophages and the higher rate of degranulation of i.p . enzymes in breed A were associated with a greater number of surviving i.p . S . Enteritidis cells . In response to outbreaks of S . Enteritidis in the field, the average mortality was significantly higher in flocks of breed A (3.2%) than in flocks of breed B (1.2%) or breed C (0.96%) (P < 0.05) . These data provide an indication of the significance of the model in reflecting the differences in resistance of S . Enteritidis of broiler breeds reared in a farm environment.

Genetics, 2000 Jan, 154(1), 27 - 37
Evolutionary reversals during viral adaptation to alternating hosts; Crill WD et al.; Experimental adaptation of the bacteriophage phiX174 to a Salmonella host depressed its ability to grow on the traditional Escherichia host, whereas adaptation to Escherichia did not appreciably affect growth on Salmonella . Continued host switching consistently exhibited this pattern . Growth inhibition on Escherichia resulted from two to three substitutions in the major capsid gene . When these phages were forced to grow again on Escherichia, fitness recovery occurred predominantly by reversions at these same sites, rather than by second-site compensatory changes, the more frequently observed mechanism in most microbial systems . The affected residues lie on the virion surface and they alter attachment efficiency, yet they occur in a region distinct from a putative binding region previously identified from X-ray crystallography . These residues not only experienced high rates of evolution in our experiments, but also exhibited high levels of radical amino acid variation among phiX174 and its known relatives, consistent with a history of adaptation involving these sites.

Microbiology, 1999 Dec, 145 ( Pt 12), 3505 - 21
Functional analysis of genes responsible for the synthesis of the B-band O antigen of Pseudomonas aeruginosa serotype O6 lipopolysaccharide; Belanger M et al.; This study reports the organization of the wbp gene cluster and characterization of a number of genes that are essential for B-band O antigen biosynthesis in the clinically prevalent Pseudomonas aeruginosa serotype 06 . Twelve genes were identified that share homology with other LPS and polysaccharide biosynthetic genes . This cluster contains homologues of wzx (encoding the O antigen flippase/translocase) and wzz (which modulates O antigen chain length distribution) genes, typical of a wzy-dependent pathway . However, a complete wzy gene (encoding the O-polymerase) was not found within the cluster . Four biosynthetic genes, wbpO, wbpP, wbpV and wbpM, and four putative glycosyltransferase genes, wbpR, wbpT, wbpU and wbpL, were identified in the cluster . To characterize their roles in LPS biosynthesis, null mutants of wbpO, wbpP, wbpV, wbpL and wbpM were generated using a gene-replacement strategy . Mutations in each of these genes caused deficiency in B-band synthesis . The wbpL mutant was deficient in both A-band and B-band LPS . WbpL(O6) is a bi-functional enzyme which could initiate B-band synthesis through the addition of QuiNAc to undecaprenol phosphate, and A-band synthesis by transferring either a GalNAc or a GlcNAc residue . Another approach used to assign function to the wbp(O6) genes was by complementation analysis . Two genes from Salmonella typhi, wcdA and wcdB, responsible for the synthesis of a homopolymer of GalNAcA called Vi antigen were used in complementation experiments to verify the functions of wbpO and wbpP . wcdA and wcdB restored B-band synthesis in wbpO and wbpP mutants respectively, implying that wbpO and wbpP are involved in UDP-GalNAcA synthesis . Although wbpV has homology to wbpK of the serotype O5 B-band LPS synthesis cluster, complementation analysis using the respective null mutants showed that the genes are not interchangeable . A knockout mutation of wbpN (located downstream of wbpM) did not abrogate LPS synthesis in either 05 or 06; therefore, it has been renamed orf48.5 . These results establish the organization of genes involved in P . aeruginosa B-band O antigen synthesis and provide the evidence to assign functions to a number of LPS biosynthetic genes.

Kansenshogaku Zasshi, 1999 Nov, 73(11), 1087 - 94
{Drug-resistance and definitive type 104 of Salmonella serovar typhimurium isolated from sporadic cases in Tokyo, 1980-1998}; Matsushita S et al.; A total of 674 Salmonella serovar Typhimurium (S . Typhimurium) strains consisting of 522 domestic strains and 152 imported strains isolated in Tokyo, 1980-1998, were examined regarding their drug-resistance and phage-type . Domestic strains accounted for 6.2% of all Salmonella (8,359 strains) isolated from domestic cases, and imported strains accounted for 3.7% of all Salmonella (4,083 strains) isolated from imported cases . A drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM, and NFLX) showed that 245 strains (46.9%) of the domestic strains and 109 strains (71.7%) of the imported strains were resistant to some of the drugs, excluding FOM and NFLX . Drugs with a high resistance rate were TC, SM, ABPC, and CP for both groups . Drug-resistance patterns of the resistant strains varied among the 40 types . Among those, prevalent patterns recognized were CP.TC.SM.ABPC, CP.TC.SM.KM.ABPC, TC.SM, SM, and TC.KM in the domestic strains, and TC, CP.TC.SM.ABPC, CP.TC.SM.KM.ABPC, CP.TC.SM.KM.ABPC.ST and TC.KM in the imported strains . The results of the phage-typing test revealed that 31 strains of 52 domestic strains tested, and 13 strains of 46 imported strains tested were definitive type 104 (DT104) . Those resistance patterns were CP.TC.SM.ABPC.SU (43 strains) and CP.TC.SM.KM.ABPC.SU (1 strain).

J Exp Med, 2000 Jan 3, 191(1), 157 - 70
Differential roles of interleukin 15 mRNA isoforms generated by alternative splicing in immune responses in vivo; Nishimura H et al.; At least two types of interleukin (IL)-15 mRNA isoforms are generated by alternative splicing at the 5' upstream of exon 5 in mice . To elucidate the potential roles of IL-15 isoforms in immune responses in vivo, we constructed two groups of transgenic mice using originally described IL-15 cDNA with a normal exon 5 (normal IL-15 transgenic {Tg} mice) and IL-15 cDNA with an alternative exon 5 (alternative IL-15 Tg mice) under the control of an MHC class I promoter . Normal IL-15 Tg mice constitutionally produced a significant level of IL-15 protein and had markedly increased numbers of memory type (CD44(high) Ly6C(+)) of CD8(+) T cells in the LN . These mice showed resistance to Salmonella infection accompanied by the enhanced interferon (IFN)-gamma production, but depletion of CD8(+) T cells exaggerated the bacterial growth, suggesting that the IL-15-dependent CD8(+) T cells with a memory phenotype may serve to protect against Salmonella infection in normal IL-15 Tg mice . On the other hand, a large amount of intracellular IL-15 protein was detected but hardly secreted extracellularly in alternative IL-15 Tg mice . Although most of the T cells developed normally in the alternative IL-15 Tg mice, they showed impaired IFN-gamma production upon TCR engagement . The alternative IL-15 transgenic mice were susceptible to Salmonella accompanied by impaired production of endogenous IL-15 and IFN-gamma . Thus, two groups of IL-15 Tg mice may provide information concerning the different roles of IL-15 isoforms in the immune system in vivo.

Environ Mol Mutagen, 1999, 34(4), 297 - 304
Prediction of rodent carcinogenicity utilizing a battery of in vitro and in vivo genotoxicity tests; Kim BS et al.; The primary purpose of this study is to investigate the degree to which we can improve the prediction of rodent carcinogenicity (CA) by combining results from an in vitro and two in vivo genotoxicity tests . We used the Ames Salmonella assay (SAL) for the in vitro test and the micronucleus assay (MNC) and chromosome aberration assay (ABS) in mouse bone marrow cells for the two in vivo tests . We collected complete assay data for 82 chemicals (55 carcinogens and 27 noncarcinogens) from the NTP data base and the IARC monograph series . Our results indicate that: (1) only SAL affects the predictivity of CA, (2) MNC has a strong association with ABS, and (3) SAL predicts ABS . It has been known for some time that once the SAL assay result is available for prediction, other in vitro mutation tests provide little additional information for predicting CA . Our study indicates that the same conclusion holds for CA, SAL, MNC, and ABS .

J Clin Microbiol, 2000 Jan, 38(1), 292 - 300
Molecular methods for the epidemiological typing of Salmonella enterica serotype Typhi from Hong Kong and Vietnam; Ling JM et al.; A total of 217 and 73 strains of Salmonella enterica serotype Typhi isolated from 1985 to 1997 in Hong Kong and in 2 months of 1989 and 1990 in Vietnam, respectively, were studied . These isolates were typed by plasmid profile analysis, plasmid fingerprinting, ribotyping with PstI, and total DNA fingerprinting with NarI . There appeared to be no major outbreak of typhoid fever in Hong Kong during the study period since there was considerable heterogeneity among the isolates . Isolates from Hong Kong were different from those from Vietnam . Thirty-seven percent of Vietnamese isolates belonged to two predominant clones, with the rest being heterogeneous in nature . Total DNA fingerprinting supplemented with ribotyping could be a reliable and rapid method for epidemiological typing of S . enterica serotype Typhi.

Life Sci, 1999, 65(24), 2541 - 52
Effect of sulfatide on acute lung injury during endotoxemia in rats; Squadrito F et al.; Experimental studies have shown that intrapulmonary leukocyte sequestration and activation is implicated in the pathogenesis of acute lung injury during endotoxemia . Selectins are involved in the adhesion of leukocyte to the endothelium . Sulfatide is recognized by P selectin and blocks this adhesion molecule . We studied the effects of sulfatide on endotoxin-induced lung damage in rats . Endotoxin shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg/kg of Salmonella enteritidis lipopolysaccharide (LPS) . LPS administration reduced survival rate (0%, 72 h after endotoxin challenge) decreased mean arterial blood pressure (MAP), produced leukopenia (Controls = 11,234+/-231 cells/mL, LPS = 4,567+/-123 cells/mL) and increased lung myeloperoxidase activity (MPO; a marker of leukocyte accumulation) in the lung (Controls = 0.35+/-0.1 U/g/tissue; LPS = 10+/-1.2 U/g/tissue) . Furthermore LPS administration markedly impaired the concentration-response curves for acetylcholine and sodium nitroprusside in isolated pulmonary arterial rings . There was also an increased staining for P-selectin in the pulmonary arteries . Sulfatide treatment (10 mg/kg, 30 min . after LPS challenge), significantly protected against LPS-induced lethality (90% survival rate and 70% survival rate 24 h and 72 h after LPS injection), reduced LPS induced hypotension, reverted leukopenia (8,895+/-234 cells/ml) and lowered lung MPO activity (1.7+/-0.9 U/g/tissue) . Furthermore sulfatide restored to control values the LPS-induced impairment in arterial pulmonary vasorelaxation and reduced P-selectin immunostaining . Our data indicate that sulfatide attenuates LPS-induced lung injury and protects against endotoxin shock.

Appl Environ Microbiol, 2000 Jan, 66(1), 419 - 21
Two murine monoclonal antibodies against serogroup E Salmonellae; Ng SP et al.; A monoclonal antibody (MAb), MO15, was raised against the lipopolysaccharide antigen of an epsilon15-lysogenized serogroup E(1) Salmonella strain . The O factor 15-specific MAb MO15, together with another serogroup E-specific MAb, can differentiate among phage lysogenization variants in serogroup E salmonellae . Their epitope specificities in relation to conventional O-antigenic structures are discussed.

Br J Nutr, 1999 May, 81(5), 349 - 58
Dietary nitrate in man: friend or foe?
McKnight GM, Duncan CW, Leifert C, Golden MH.
Based on the premise that dietary nitrate is detrimental to human health, increasingly stringent regulations are being instituted to lower nitrate levels in food and water . Not only does this pose a financial challenge to water boards and a threat to vegetable production in Northern Europe, but also may be eliminating an important non-immune mechanism for host defence . Until recently nitrate was perceived as a purely harmful dietary component which causes infantile methaemoglobinaemia, carcinogenesis and possibly even teratogenesis . Epidemiological studies have failed to substantiate this . It has been shown that dietary nitrate undergoes enterosalivary circulation . It is recirculated in the blood, concentrated by the salivary glands, secreted in the saliva and reduced to nitrite by facultative Gram-positive anaerobes (Staphylococcus sciuri and S . intermedius) on the tongue . Salivary nitrite is swallowed into the acidic stomach where it is reduced to large quantities of NO and other oxides of N and, conceivably, also contributes to the formation of systemic S-nitrosothiols . NO and solutions of acidified nitrite, mimicking gastric conditions, have been shown to have antimicrobial activity against a wide range of organisms . In particular, acidified nitrite is bactericidal for a variety of gastrointestinal pathogens such as Yersinia and Salmonella . NO is known to have vasodilator properties and to modulate platelet function, as are S-nitrosothiols . Thus, nitrate in the diet, which determines reactive nitrogen oxide species production in the stomach (McKnight et al . 1997), is emerging as an effective host defence against gastrointestinal pathogens, as a modulator of platelet activity and possibly even of gastrointestinal motility and microcirculation . Therefore dietary nitrate may have an important therapeutic role to play, not least in the immunocompromised and in refugees who are at particular risk of contracting gastroenteritides.

Vet Immunol Immunopathol, 1999 Dec 15, 72(1-2), 135 - 42
Analysis of the mucosal microenvironment: factors determining successful responses to mucosal vaccines; Husband AJ et al.; The predominance of IgA antibodies in mucosal sites reflects a combination of high rate IgA isotype switching among precursor cells in induction sites, their selective localisation in mucosal effector tissues and vigorous proliferation of these cells after extravasation . Each of these steps leading to IgA expression at the mucosa is under cytokine control . This paper will address the role of cytokines in induction and expression of IgA responses, the contribution of various precursor cell subsets and their differential responses to cytokine signals and strategies for manipulating cytokine expression . With respect to IgA antibody production in the gut whereas IL-4 and TGF-beta have been implicated in isotype switching of precursor cells to IgA commitment, their subsequent localisation, proliferation and effector activity expression is dependent on IL-5 and IL-6 expression locally . Most IgA plasma cells in the intestine derive from cells of the B2 lineage in the Peyer's patch, but a subpopulation of cells derived from the peritoneal cavity (B1 cells) also contribute to the IgA plasma cell population in the intestinal lamina propria . Whereas IgA+ cells of the B2 lineage are IL-6 dependent but IL-5 independent, B1-derived IgA+ cells are IL-5 dependent and IL-6 independent . On the other hand, cell mediated immune responses in the gut are highly dependent on IFN-gamma production by both Th1 CD4 cells and CD8 cells and in enteric Salmonella infection IFN-gamma production is essential but antibody has little effect on this process.Therapeutic interventions based on the information emerging from these studies will lead to improved vaccination responses and correction of immunodeficiencies especially in young animals.

J Bacteriol, 2000 Jan, 182(1), 236 - 40
Reduced flux through the purine biosynthetic pathway results in an increased requirement for coenzyme A in thiamine synthesis in Salmonella enterica serovar typhimurium; Frodyma M et al.; Work presented here establishes a connection between cellular coenzyme A (CoA) levels and thiamine biosynthesis in Salmonella enterica serovar Typhimurium . Prior work showed that panE mutants (panE encodes ketopantoate reductase) had a conditional requirement for thiamine or pantothenate . Data presented herein show that the nutritional requirement of panE mutants for either thiamine or pantothenate is manifest only when flux through the purine biosynthetic pathway is reduced . Further, the data show that under the above conditions it is the lack of thiamine pyrophosphate, and not decreased CoA levels, that directly prevents growth.

J Bacteriol, 2000 Jan, 182(1), 228 - 32
Lesions in the nuo operon, encoding NADH dehydrogenase complex I, prevent PurF-independent thiamine synthesis and reduce flux through the oxidative pentose phosphate pathway in Salmonella enterica serovar typhimurium; Claas K et al.; In Salmonella enterica serovar Typhimurium, PurF-independent thiamine synthesis (or alternative pyrimidine biosynthesis) allows strains, under some growth conditions, to synthesize thiamine in the absence of the first step in the purine biosynthetic pathway . Mutations have been isolated in a number of loci that prevent this synthesis and thus result in an Apb(-) phenotype . Here we identify a new class of mutations that prevent PurF-independent thiamine synthesis and show that they are defective in the nuo genes, which encode the major, energy-generating NADH dehydrogenase of the cell . Data presented here indicated that a nuo mutant has reduced flux through the oxidative pentose phosphate pathway that may contribute to, but is not sufficient to cause, the observed thiamine requirement . We suggest that reduction of the oxidative pentose phosphate pathway capacity in a nuo mutant is an attempt to restore the ratio between reduced and oxidized pyridine nucleotide pools.

J Bacteriol, 2000 Jan, 182(1), 23 - 9
Identification of SoxS-regulated genes in Salmonella enterica serovar typhimurium; Pomposiello PJ et al.; Salmonella enterica serovar Typhimurium responds to superoxide-generating agents through soxR-mediated activation of the soxS gene, whose product, SoxS, is necessary for resistance to oxidative stress . The S . enterica serovar Typhimurium soxRS system also mediates redox-inducible resistance to diverse antibiotics, which may be relevant to clinical infections . In order to identify SoxS-regulated genes in S . enterica serovar Typhimurium, a lacI-regulated expression system for the S . enterica serovar Typhimurium soxS gene was developed . This system was used to demonstrate that soxS expression is sufficient for the induction of resistance to the superoxide-generating drug paraquat and for the transcriptional activation of the sodA and micF genes . In addition, a library of random lacZ insertions was generated and screened for clones displaying differential beta-galactosidase activity in the presence or absence of SoxS . This selection yielded six independent chromosomal lacZ transcriptional fusions that were activated by either artificial expression of SoxS or exposure of wild-type cells to micromolar concentrations of paraquat . Moreover, disruption of the inducible genes by the insertions rendered S . enterica serovar Typhimurium hypersensitive to millimolar concentrations of paraquat . Nucleotide sequence determination identified the disrupted genes as sodA (Mn-containing superoxide dismutase), fpr (NADPH:ferredoxin oxidoreductase), and ydbK (a putative Fe-S-containing reductase).

Microbes Infect, 1999 Jul, 1(9), 719 - 26
Host cytokine response and resistance to Salmonella infection; Lalmanach AC et al.; Knowledge of the host response, of the resistance process, and of the mediators committed against Salmonella infection is essential to progress towards better means of prophylaxis and eradication . In this context, the present contribution attempts to interconnect, with the pivotal role of the macrophage, the early resistance process under the control of the Nramp1 gene and the cytokine response for resolving infection . IL-12 produced by macrophages is an inducer of IFN-gamma production, which in turn activates the macrophage antibacterial activity and synergizes its effects with TNF-alpha . All three of these cytokines are powerful actors in the first line of anti-Salmonella defence . It can be pointed out that susceptible and resistant individuals do not seem to see the cytokine environment the same way, the former being unresponsive to IL-1 or GM-CSF treatment and deficient in IFN-gamma production . These discrepancies may rely on cell signalling events that could be defective in macrophages of the susceptible phenotype.

Avian Dis, 1999 Oct-Dec, 43(4), 774 - 8
Experimental horizontal transmission of Salmonella enteritidis strains (phage types 4, 8, and 13a) in chicks; Gast RK et al.; The recent isolation of phage type 4 Salmonella enteritidis strains from poultry and humans in the United States has generated considerable concern because this phage type is predominant in both animals and humans in many other nations . Understanding whether the presence of these strains in poultry flocks poses an elevated threat to public health is a critical issue for developing effective disease control programs . The present study evaluated whether S . enteritidis strains of various phage types found in poultry in the United States (phage types 4, 8, and 13a) differed in their potential for horizontal transmission from experimentally infected chicks to uninoculated chicks housed in the same isolator units . Five days after two seeder chicks in each group of 12 were inoculated with oral doses of approximately 10(3) S . enteritidis cells at 8 days of age, ceca and livers were sampled from seeder chicks and from their contact-exposed penmates . On the basis of the detection of S . enteritidis in cecal samples, phage type 4 strains were transmitted horizontally at a significantly lower frequency than were strains of other phage types . Nevertheless, two of three phage type 4 strains evaluated were very highly invasive.

Avian Dis, 1999 Oct-Dec, 43(4), 685 - 95
Temporal changes in the population genetics of Salmonella pullorum; Dodson SV et al.; Salmonella pullorum is the cause of pullorum disease, which is characterized by white diarrhea and a high mortality rate in poultry . During the 1990s, the serologic "pullorum" test has occasionally failed to detect infected birds during the early stage of disease . To determine if any recent genetic changes have taken place in S . pullorum to account for poor seroconversion sometimes observed in infected flocks, S . pullorum from 1990s outbreaks and strains isolated prior to the 1980s were typed by random amplified polymorphic DNA (RAPD) . Of 40 S . pullorum isolates typed by this method, eight distinct DNA patterns were identified with one of three RAPD polymerase chain reaction primers . Sixty-two percent of S . pullorum isolates shared the same RAPD DNA pattern, and a major proportion of these strains were from recent flock infections . The RAPD patterns for S . pullorum were clearly distinct from the avian Salmonella group B isolates included in this analysis . The distribution of Salmonella virulence genes among avian Salmonella isolates was also examined . Eighty-five percent of the S . pullorum isolates had both the virulence plasmid gene, spvB, and the invasion gene, invA, with the same percentage positive for the Salmonella enteriditis fimbrial gene, sef . However, significant variability was observed among S . pullorum in their ability to invade avian epithelial cells, despite the presence of the Salmonella invasion gene in these isolates.

Avian Dis, 1999 Oct-Dec, 43(4), 664 - 9
Field observations with Salmonella enteritidis bacterins; Davison S et al.; A study involving 11 commercial layer flocks was conducted to determine the efficacy of Salmonella enteritidis bacterins (autogenous or federally licensed) . The criterion for evaluation of vaccine efficacy was the presence or absence of S . enteritidis in the environment, the organs of the bird (including ovary and oviduct), and eggs . Environmental, rodent, and organ specimens from dead birds as well as eggs were cultured throughout the life of the flock . All layers were obtained from pullet sources that were negative for S . enteritidis, as determined by organ and environmental cultures . Despite the use of S . enteritidis vaccination, 63.6% of the houses had S . enteritidis-positive environmental cultures and 100% of the flocks had S . enteritidis organ-culture-positive birds . The range of positive cultures for S . enteritidis in the environment in vaccinated flocks was between 0 and 45.5% . Birds in vaccinated flocks were organ-culture positive for S . enteritidis between 10% and 40% of the time . The unvaccinated portion of flocks in the same house and the unvaccinated flock in a complex had similar results compared with the vaccinated portion of the flocks.

Curr Biol, 1999 Dec 16-30, 9(24), 1477 - 80
Environmentally constrained mutation and adaptive evolution in Salmonella; Massey RC et al.; The relationship between environment and mutation is complex {1} . Claims of Lamarkian mutation {2} have proved unfounded {3-5}; it is apparent, however, that the external environment can influence the generation of heritable variation, through either direct effects on DNA sequence {6} or DNA maintenance and copying mechanisms {7-10}, or as a consequence of evolutionary processes {11-16} . The spectrum of mutational events subject to environmental influence is unknown {6} and precisely how environmental signals modulate mutation is unclear . Evidence from bacteria suggests that a transient recombination-dependent hypermutational state can be induced by starvation {5} . It is also apparent that changes in the mutability of specific loci can be influenced by alterations in DNA topology {10,17} . Here we describe a remarkable instance of adaptive evolution in Salmonella which is caused by a mutation that occurs in intermediate-strength osmotic environments . We show that the mutation is not 'directed' and describe its genetic basis . We also present compelling evidence in support of the hypothesis that the mutational event is constrained by signals transmitted from the external environment via changes in the activity of DNA gyrase.

Pediatr Infect Dis J, 1999 Dec, 18(12), 1073 - 7
Non-typhi Salmonella bacteremia in children; Zaidi E et al.; BACKGROUND: Non-typhi Salmonella (NTS) infections are a frequent cause of self-limited diarrheal illness in healthy children . Bacteremia is a known complication of NTS infection, but the management of children with bacteremia has been based on limited data . OBJECTIVE: To study the outcomes of pediatric patients with NTS bacteremia . METHODS: Retrospective review of patients with NTS bacteremia covering a 16-year period at an urban pediatric hospital . Clinical data from the initial visits and any follow-up visits or hospitalizations were abstracted from the medical record . RESULTS: We studied 144 patients . Median age was 10.5 months . Fifty-four patients were hospitalized at the initial visit including all the patients with immunodeficiency (n = 12) . Of the 90 patients initially managed as outpatients, 79 were subsequently admitted; only 1 of these patients developed a focal complication . Persistent bacteremia was found in 51 (41%) patients . Among nonimmunocompromised patients, persistent bacteremia was noted in 34% {95% confidence interval (CI), 20 to 52%} of those initially treated with oral antibiotics, 52% (CI 30 to 74%) of those initially treated with a parenteral dose of antibiotics and in 31% (CI 22 to 43%) of those who were not initially given antibiotics . No laboratory or clinical factors predicted persistent bacteremia . Twelve patients developed focal infections: 3 of 119 previously healthy children (2.5%, CI 0.5 to 7%); and 9 of 25 children with underlying medical conditions (36%, CI 19 to 57%) . Focal infections included meningitis (3), osteomyelitis (4), septic arthritis (2), pneumonia (2) and cholangitis (1) . CONCLUSIONS: NTS bacteremia occurs in otherwise healthy children, although the risk of focal infections is small . Patients with NTS bacteremia frequently have persistent bacteremia at follow-up regardless of initial antibiotic treatment.

J Agric Food Chem, 1999 Dec, 47(12), 4956 - 61
Comparison in metabolic activity of cytochrome P450 1A1 on heterocyclic amines between human and rat; Kanazawa K et al.; In mutagenicity and antimutagenicity tests, the toxicants have been activated to the ultimate mutagenic forms usually with rat cytochrome P450 (CYP) enzymes . An understanding is important of whether these data can be available for human . In this paper are compared the activating abilities of CYP1A1 between human and rat using recombinant yeast cells that express respective CYP1A1 and yeast NADPH-CYP-oxidoreductase simultaneously . Three different types of dietary procarcinogens, heterocyclic amines, were tested by two methods: a bioassay with Salmonella mutagenicity test and a chemical determination of N-hydroxyls as the ultimate mutagenic forms . Compared with ED(50) values, saturation levels, and V(max)/K(m) values at an initial stage of the enzyme activity, human and rat CYP1A1 showed almost similar abilities for the metabolic activation on heterocyclic amines . The two enzymes also had the same preference for the tested procarcinogens and the same affinities to the specific inhibitors such as flavonoids.

Zentralbl Bakteriol, 1999 Oct, 289(4), 457 - 74
Isolation and characterisation of four distinct cytotoxic factors of Salmonella Weltevreden; Singh BR et al.; Four distinct cytotoxins with different biological, physico-chemical and antigenic characteristics were isolated from a single Salmonella Weltevreden strain recovered from buffalo meat . The toxins were purified by means of salt precipitation, dialysis, gel filtration and ion-exchange chromatographic methods . Cytotoxin I was dermonecrotic, verocytotoxic and lethal for the mouse (LD50 120 micrograms) . It induced accumulation of serosanguinous fluid in the rabbit ligated ileal loop (RLIL) and mucinous fluid in the stomach . It was active within a narrow pH range (5.0-8.0) and lost its activity on autoclaving for 1 min . Cytotoxin II was verocytotoxic, enterotoxic and lethal to for the mouse (LD50, 1 mg) . It induced delayed vasopermeability in rabbit skin, was active at between pH 5.6 and 8.4 only and heat-sensitive (100 degrees C, 30 min) . Cytotoxin III was neither dermatotoxic nor enterotoxic . It induced vacuolation, multinucleation and formation of syncytia in Vero cells . It was pH-sensitive beyond the range of 4.8 to 8.2 . It was completely inactivated on boiling for 30 min . Cytotoxin IV was intensely necrotizing to rabbit skin within 6 h of inoculation and lysed Vero cells . It also possessed haemolytic and lecithinase/phospholipase-C activities . The cytotoxin lost its activity on heating at 90 degrees C (30 min) but remained active between pH 2.5 and 7.5 . The PIs of the cytotoxins were estimated to be 9.0, 7.0, 5.6 and 3.0, respectively . All the four cytotoxins were immunogenic in rabbits but antigenically unrelated as the anticytotoxin neutralized only the homologous cytotoxin and did not cross-react with heterologous cytotoxins.

Zentralbl Bakteriol, 1999 Oct, 289(4), 399 - 414
Clonal relationship of Salmonella enterica serovar typhimurium phage type DT104 in Germany and Austria; Prager R et al.; A new epidemic clone of Salmonella enterica serovar Typhimurium designated definitive phage type (DT) 104 has been emerging since 1990 to become most common type among S . Typhimurium isolates in Germany and Austria . Molecular fingerprinting (PFGE-pattern, plasmid profiles, IS200 pattern, ribotype, ERIC-type, OMP and MLE patterns) revealed the majority of the DT104 isolates to have clonal identity; they were designated as type 1 (about 95%) . Moreover, clonal type 1 of DT104 was found to occur in sensitive as well as in a range of multiply drug-resistant variants and in a variety of plasmid profile types (in particular with small cryptic plasmids in the range of 1.0 to 5.0 Md) . Since the clonal type 1 of DT104 has been identified among isolates from other countries, too, including such from the United Kingdom, the United Arab Emirates, the Philippines, and the Netherlands, its pandemic spread in man indicates that the import/export of this pathogen continues . About 5% of the DT104 isolates have been identified as genetically diverse indicating the independent appearance of the same multiple drug resistance and phage pattern phenotype among different Salmonella ancestor strains.

Schweiz Arch Tierheilkd, 1999, 141(11), 509 - 15
{The prevalence of salmonella, yersinia and mycobacteria in slaughtered pigs in Switzerland}; Offermann U et al.; Clinically healthy food animals can be reservoirs for various foodborne pathogens . In general, such animals do not have lesions that are visible during meat inspection . Pigs are considered to be carriers of salmonella, yersinia and mycobacteria, but the risk of transmission to humans is difficult to assess . The aim of this study was to estimate the actual prevalence of the three above mentioned pathogens in the Swiss pig population and to comment on their significance . A total of 570 samples each of tonsils and mesenteric lymphnodes, were collected at two slaughterhouses from carcasses of apparently healthy pigs and analyzed for the presence of salmonella, yersinia and mycobacteria . The prevalence of salmonella (0.9%) was found to be lower than--while that of yersinia (8.1%) and mycobacteria (12.8%) about equal to--results reported from other European countries . Yersinia typing showed that serotype O:9 of Yersinia enterocolitica (2.5%) was 6 to 7 times more frequent than serotype O:3 (0.4%)--formerly the most frequent serotype . Mycobacterium avium was the most frequent isolate (90.7%) among the mycobacteria isolated . Although all three pathogens are present in the Swiss pig population, we consider the risk of transmission to humans via consumption of pork as low . Appropriate preventive measures and quality management should contribute to keep the risk under control.

Scand J Immunol, 1999 Dec, 50(6), 555 - 61
Low concentrations of immunoglobulin G antibodies to Salmonella serogroup C in C2 deficiency: suggestion of a mannan-binding lectin pathway-dependent mechanism; Selander B et al.; The influence of complement on immune responses to polysaccharides is debatable . We examined the serum concentrations of IgM and IgG antibody against Salmonella O-antigen specific oligosaccharides representing the serogroups B, C and D, and against capsular polysaccharides of Streptococcus pneumoniae serotypes 6 and 23 in C2-deficient adults and in healthy controls . A sharp contrast of findings was found for antibodies against the CO antigen, an activator of the mannan-binding lectin (MBL) pathway of complement activation . The C2-deficient group showed normal IgM and markedly low IgG antibody levels . Similar findings were made in adults with low concentrations of MBL . This suggests that the recruitment of classical pathway C3 convertase through the MBL pathway is critically involved in isotype switching of antibodies against MBL pathway activating antigens during immune system maturation . The findings imply a new role of the MBL pathway, and an additional link between innate and acquired immunity . Specific IgM against BO was moderately low in C2 deficiency . Other differences for the Salmonella antigens were not found . Markedly raised IgM antibody levels against pneumococcal polysaccharides in C2 deficiency probably Salmonella reflected past infections . The absence of a concomitant increase of specific IgG might possibly be explained by impaired IgM to IgG switching.

J Food Prot, 1999 Dec, 62(12), 1387 - 93
Evaluation of a polymerase chain reaction-based test for detecting Salmonella spp . in food samples: Probelia Salmonella spp; Fach P et al.; A commercially available polymerase chain reaction (PCR) kit was evaluated for the detection of Salmonella spp . in food samples . The test combines PCR amplification and sandwich hybridization of the amplified DNA in microtiter plates . The sensitivity and specificity was evaluated with 52 Salmonella strains and 51 non-Salmonella strains and showed that the test was entirely reliable . The threshold sensitivity was 10(2) CFU/ml . The limit of detection of dead cells that determines the minimum detection level of dead cells in food samples was superior to 10(6) CFU/25 g, a level rarely achieved in naturally contaminated samples . After an 18-h pre-enrichment step, the test could detect viable Salmonella in artificially contaminated food samples, even for the lower contamination level (3 CFU/25 g) . There was complete agreement between the PCR test and the ISO 6579 bacteriological reference method with artificially contaminated samples . Regarding the accuracy of the results obtained from 253 naturally or noncontaminated foods and from 32 artificially contaminated foods, the agreement percentage was 99.6% . The fidelity of the technique was evaluated in a collaborative study with eight European laboratories and showed a correlation of 98.4%.

J Food Prot, 1999 Dec, 62(12), 1381 - 6
High intensity pulsed electric fields applied to egg white: effect on Salmonella Enteritidis inactivation and protein denaturation; Jeantet R et al.; High-intensity electric fields have been successfully applied to the destruction of Salmonella Enteritidis in diaultrafiltered egg white . The effects of electric field strength (from 20 to 35 kV x cm(-1)), pulse frequency (from 100 to 900 Hz), pulse number (from 2 to 8), temperature (from 4 to 30 degrees C), pH (from 7 to 9), and inoculum size (from 10(3) to 10(7) CFU x ml(-1)) were tested through a multifactorial experimental design . Experimental results indicate that, for Salmonella inactivation, the electric field intensity is the dominant factor with a strongly positive effect, strengthened by its positive interaction with pulse number . Pulse number, temperature, and pH have also significant positive effects but to a lesser extent . In the most efficient conditions, the pulsed electric field (PEF) treatment is capable of 3.5 log10 reduction in viable salmonellae . Simultaneously, the measure of surface hydrophobicity does not indicate any increase after PEF treatment . These results suggest that no protein denaturation occurs, unlike what is observed after comparable heat treatment in terms of Salmonella inactivation (55 degrees C for 15 min).

J Food Prot, 1999 Dec, 62(12), 1376 - 80
Mucosal competitive exclusion to reduce Salmonella in swine; Fedorka-Cray PJ et al.; A mucosal competitive exclusion culture has been shown to reduce or eliminate Salmonella spp . in poultry . Using similar techniques, a mucosal competitive exclusion culture from swine (MCES) was produced from the cecum of a 6-week-old pig . Suckling pigs were inoculated with 5 ml of MCES by oral gavage within 6 h postfarrowing (PF) and again at 24 h PE All pigs were challenged with 10(3) CFU of Salmonella Choleraesuis at 48 h PF by intranasal instillation, including pigs from two sows that had not been given MCES . Clinical signs and rectal swabs were monitored daily, and pigs were allowed to suckle throughout the experiment . All pigs underwent necropsy on day 7 PF, and presence of Salmonella was determined in both qualitative (10 tissues) and quantitative (two tissues) samples . Clinical signs were inapparent in all pigs throughout the experiment . Recovery of Salmonella from rectal swabs was variable . However, 28% of the gut tissues were positive from the MCES-treated pigs versus 79% from the control pigs . A 2- to 5-log10 reduction of Salmonella in the cecal contents or ileocolic junction was observed in the MCES-treated pigs when compared with the controls . These data indicate that use of MCES may be a useful approach for control of Salmonella.

Presse Med, 1999 Nov 27, 28(37), 2034 - 6
{Chronic septic granulomatous disease . 14 cases}; Barbouche MR et al.; OBJECTIVES: Chronic granulomatous disease (CGD) is a rare inherited immunodeficiency . Affected children are mostly boys . The most common clinical features are recurrent bacterial and fungal infections starting at early childhood . We report 14 cases, including 5 girls, of CGD in Tunisian children . PATIENTS AND METHODS: This retrospective study concerned 14 clinical observations of CGD recorded between April 1988 and December 1998 . The diagnosis was established upon determination of a defective respiratory burst in the patients' neutrophils at the tetrazolium nitroblue test (NBT) . In 4 cases, the diagnosis was also confirmed by chemiluminescence assay . RESULTS: The patients (9 boys and 5 girls) belonged to 12 families, 75% of which were consanguineous . In 6 families, there had been several deaths in early childhood . The mean age at onset of clinical signs was 6.8 months (7 days to 24 months) . Clinical signs included lung (10 cases), nodal (8 cases), skin (7 cases), and intestinal (7 cases) infections . Seven patients developed invasive pulmonary aspergillosis with parietal extension in 4 cases . Salmonella and Staphylococcus infections were rare in our series . Six children (42.8%) including 2 girls, died . Aspergillosis was fatal in 4 cases . CONCLUSION: Recurrent infections are the main clinical fetus of chronic granulomatous disease . Prognosis has been improved by the use of prophylactic antibiotics . Early diagnosis of the disease is crucial.

Rev Med Liege, 1999 Oct, 54(10), 786 - 8
{Clinical case of the month . Rupture of Salmonella mycotic aneurysm of the infrarenal abdominal aorta}; Schils F et al.; Mycotic aneurysms are uncommon but remain one of the most challenging clinical problems for the vascular surgeon . They are associated with high morbidity and mortality, and the clinical signs and symptoms are non specific . We report here the case of an abdominal aorta mycotic aneurysm due to salmonellosis treated by insertion of an arterial homograft.

Infect Immun, 2000 Jan, 68(1), 205 - 13
In vivo characterization of the murine intranasal model for assessing the immunogenicity of attenuated Salmonella enterica serovar Typhi strains as live mucosal vaccines and as live vectors; Pickett TE et al.; Attenuated Salmonella enterica serovar Typhi live vector vaccine strains are highly immunogenic in mice following intranasal but not orogastric inoculation . To elucidate the relationship between organs within which vaccine organisms are found and the induction of specific serum immunoglobulin G (IgG) antibodies, we examined the in vivo distribution of serovar Typhi vaccine strain CVD 908-htrA following intranasal administration . Vaccine organisms were cultured from the nasal lymphoid tissue (NALT), lungs, and Peyer's patches 2 min after intranasal inoculation . Vaccine organisms persisted longer in NALT than in other organs . By decreasing the volume of intranasal inoculum containing 10(9) CFU (from a single 30- or 10-microl dose to four 2.5-microl doses given over the course of 1 h), we were able to significantly reduce the number of vaccine organisms isolated from the lungs (P < 0.05) without reducing the number of vaccine organisms in NALT . Reducing the number of vaccine organisms in the lungs resulted in a significant decrease in the serum tetanus antitoxin response elicited by CVD 908-htrA expressing tetanus toxin fragment C under the control of the redox-responsive nir15 promoter . In contrast, a similar construct expressing tetanus toxin fragment C under control of the constitutive lpp promoter stimulated a strong serum IgG tetanus antitoxin response with both inoculation regimens . The data suggest that following intranasal inoculation, NALT is a sufficient inductive site for elicitation of an immune response against both the live vector and heterologous antigen and, as occurs following oral inoculation of humans, attenuated serovar Typhi vaccine organisms elicit serum IgG responses.

Infect Immun, 2000 Jan, 68(1), 46 - 53
Igh-6(-/-) (B-cell-deficient) mice fail to mount solid acquired resistance to oral challenge with virulent Salmonella enterica serovar typhimurium and show impaired Th1 T-cell responses to Salmonella antigens; Mastroeni P et al.; In the present study we evaluated the role of B cells in acquired immunity to Salmonella infection by using gene-targeted B-cell-deficient innately susceptible mice on a C57BL/6 background (Igh-6(-/-)) . Igh-6(-/-) mice immunized with a live, attenuated aroA Salmonella enterica serovar Typhimurium vaccine strain showed impaired long-term acquired resistance against the virulent serovar Typhimurium strain C5 . Igh-6(-/-) mice were able to control a primary infection and to clear the inoculum from the reticuloendothelial system . However, Igh-6(-/-) mice, unlike Igh-6(+/+) C57BL/6 controls, did not survive an oral challenge with strain C5 at 4 months after vaccination . Transfer of immune serum did not restore resistance in Igh-6(-/-) mice . Total splenocytes and purified CD4(+) T cells obtained from Igh-6(-/-) mice 4 months after vaccination showed reduced ability to release Th1-type cytokines (interleukin 2 and gamma interferon) upon in vitro restimulation with serovar Typhimurium soluble cell extracts compared to cells obtained from Igh-6(+/+) C57BL/6 control mice . Therefore, the impaired resistance to oral challenge with virulent serovar Typhimurium observed in B-cell-deficient mice, which cannot be restored by passive transfer of Salmonella-immune serum, may be in part due to a reduced serovar Typhimurium-specific T-cell response following primary immunization.

Infect Immun, 2000 Jan, 68(1), 1 - 5
Lipopolysaccharide-induced biliary factors enhance invasion of Salmonella enteritidis in a rat model; Islam AF et al.; In this study, the role of the hepatobiliary system in the early pathogenesis of Salmonella enteritidis infection was investigated in a rat model . Intravenous (i.v.) challenge with lipopolysaccharide (LPS) has previously been shown to enhance the translocation of normal gut flora . We first confirmed that LPS can similarly promote the invasion of S . enteritidis . Oral infection of outbred Australian Albino Wistar rats with 10(6) to 10(7) CFU of S . enteritidis led to widespread tissue invasion after days . If animals were similarly challenged after intravenous administration of S . enteritidis LPS (3 to 900 microg/kg of body weight), significant invasion of the livers and mesenteric lymph nodes (MLN) occurred within 24 h, with invasion of the liver increasing in a dose-dependent fashion (P < 0.01) . If bile was prevented from reaching the intestine by bile duct ligation or cannulation, bacterial invasion of the liver and MLN was almost totally abrogated (P < 0.001) . As i.v . challenge with LPS could induce the delivery of inflammatory mediators into the bile, biliary tumor necrosis factor alpha (TNF-alpha) concentrations were measured by bioassay . Biliary concentrations of TNF-alpha rose shortly after LPS challenge, peaked with a mean concentration of 27.0 ng/ml at around 1 h postchallenge, and returned to baseline levels (3.1 ng/ml) after 2.5 h . Although TNF-alpha cannot be directly implicated in the invasion process, we conclude that the invasiveness of the enteric pathogen S . enteritidis is enhanced by the presence of LPS in the blood and that this enhanced invasion is at least in part a consequence of the delivery of inflammatory mediators to the gastrointestinal tract by the hepatobiliary system.

Emerg Infect Dis, 1999 Nov-Dec, 5(6), 802 - 6
Changes in antimicrobial resistance among Salmonella enterica Serovar typhimurium isolates from humans and cattle in the Northwestern United States, 1982-1997; Davis MA et al.; We compared antimicrobial resistance patterns of Salmonella enterica serovar Typhimurium (ST) of isolates from humans (n = 715) and cattle (n = 378) in the Pacific Northwest from 1982 through 1997 . The major changes in antimicrobial resistance can be attributed to the widespread clonal dissemination of multidrug-resistant definitive phage type 104 ST.

Berl Munch Tierarztl Wochenschr, 1999 Oct-Nov, 112(10-11), 365 - 9
{Food as a potential vector for antibiotic resistance . 1 . Relevance of residues and selected foodborne infections and intoxicants}; Klein G; Food of animal origin has been considered as an important vector for the transfer of antibiotic resistances from animal to man . Such a transfer is possible by three ways: through antibiotic residues in food, through the transfer of resistant foodborne pathogens or through the ingestion of resistant parts of the original food microflora and resistance transfer to pathogenic microorganisms . A literature review and own investigations were performed in order to asses the potential impact of antibiotic resistance in food on the consumer health . In the first report Salmonella and Staph, aureus isolates were screened for their antibiotic resistance profiles . As a result it could be shown that residues in fresh meat or milk are quantitatively of minor interest . The resistance profile of Salmonella depended on the origin (pig or poultry), but only serovars could be identified which are generally not responsible for systemic infections . Staph . aureus isolates did not show any resistances relevant for human medicine . In these cases food can be considered as safe concerning its role as a vector for antibiotic resistances . However, a resistance monitoring seems to be necessary.

Int J Food Microbiol, 1999 Dec 1, 53(1), 53 - 60
A rapid strip immunoblot assay for the specific detection of Salmonella enteritidis infection in chickens; Rajashekara G et al.; A rapid strip immunoblot assay (RSIA) was developed using recombinant SEF14 antigen . The rSEF14-RSIA was very specific in detecting antibodies to Salmonella enteritidis in chickens . When serum samples obtained from groups of chickens (N = 5) inoculated with six different Salmonella serovars were tested in rSEF14-RSIA, only serum samples obtained from S . enteritidis inoculated birds reacted with rSEF14 antigen except for a group of chickens that had been inoculated with S . dublin . To assess the sensitivity of the rSEF14-RSIA, groups of chickens were inoculated with either 10(4) cfu or 10(10) cfu of S . enteritidis and the serum and egg yolk were analyzed for SEF14 antibodies . By 1 week after infection 66-78% of chickens were found positive for SEF14 antibodies in the serum and the number of positive birds increased subsequently to 89-100% . The S . enteritidis specific antibodies appeared as early as 6 days after infection in the egg yolk of infected chickens . The antibodies to SEF14 in both the serum and egg yolk persisted for at least 7 weeks after infection in a significant proportion of chickens . Our results suggest that rSEF14-RSIA can be a practical and efficient screening test for identifying S . enteritidis infected chickens.

Vet Res Commun, 1999 Nov, 23(7), 415 - 24
Experimental salmonellosis in guinea-pigs: haematological and biochemical studies; Gupta RP et al.; Some haematological and biochemical parameters were studied in guinea-pigs infected intraperitoneally with Salmonella dublin 493 at 1 x 10(6) viable cells per animal . The infected animals showed a rise in temperature within 24 h, followed by depression and loss of body weight . On the 15th day post infection, haematological studies revealed a significant increase in the total leukocyte count due to both lymphocytosis and neutrophilia, and a decrease in the total erythrocyte count and haemoglobin concentration . There was also a significantly higher mean corpuscular volume and lower mean corpuscular haemoglobin concentration, indicating a macrocytic hypochromic anaemia . The infection caused a significant increase in alanine aminotransferase activity and creatinine, blood urea nitrogen and globulin concentrations, and a decrease in albumin and triiodothyronine . There was no significant effect on serum total protein or on thyroxine, or in the activity of aspartate aminotransferase in the serum.

J Agric Food Chem, 1999 Sep, 47(9), 3586 - 91
Determination of chlorate and chlorite and mutagenicity of seafood treated with aqueous chlorine dioxide; Kim J et al.; The use of chlorine dioxide (ClO(2)) as a potential substitute for aqueous chlorine to improve the quality of seafood products has not been approved by regulatory agencies due to health concerns related to the production of chlorite (ClO(2)(-)) and chlorate (ClO(3)(-)) as well as possible mutagenic/carcinogenic reaction products . Cubes of Atlantic salmon (Salmo salar) and red grouper (Epinephelus morio) were treated with 20 or 200 ppm aqueous chlorine or ClO(2) solutions for 5 min, and extracts of the treated fish cubes and test solutions were checked for mutagenicity using the Ames Salmonella/microsome assay . No mutagenic activity was detected in the treated fish samples or test solutions with ClO(2) . Only the sample treated with 200 ppm chlorine showed weak mutagenic activity toward S . typhimurium TA 100 . No chlorite residue was detected in sea scallops, mahi-mahi, or shrimp treated with ClO(2) at 3.9-34.9 ppm . However, low levels of chlorate residues were detected in some of the treated samples . In most cases, the increase in chlorate in treated seafood was time- and dose-related.

Microbes Infect, 1999 Jan, 1(1), 23 - 7
The natural resistance-associated macrophage protein and susceptibility to intracellular pathogens; Bellamy R; Over 20 years ago it was recognised that murine susceptibility to several antigenically unrelated pathogens was influenced by a host genetic factor . Linkage studies suggested that Lsh, Ity, and Bcg, the leishmania-, salmonella-, and mycobacteria-susceptibility genes, may be one gene, located on mouse chromosome 1 . A reverse genetics strategy identified a candidate gene, Nramp1, which was expressed only in reticuloendothelial cells . A single nonconservative amino acid substitution was found to correlate with the susceptibility genotype in 27 inbred mouse strains . The production of an Nramp1 gene-disrupted mouse and a transgenic mouse, which restored the resistance genotype, conclusively proved that Nramp1 is the Bcg/Lsh/Ity gene . The Nramp family includes genes expressed in both prokaryotic and eukaryotic species . These genes have provided clues to the possible function of Nramp1 . The ubiquitously expressed gene Nramp2 is an Fe(2+) transporter and a mutation in this gene causes microcytic anaemia in mice and rats . The functions of Nramp1 and its human homologue, NRAMP1, remain unknown, though it is hypothesised that they may regulate the intraphagosomal concentration of Fe(2+) and/or other cations . The identification of polymorphisms in the human NRAMP1 gene has facilitated studies on the relevance of this gene to human mycobacterial susceptibility . NRAMP1 variant alleles are strongly associated with tuberculosis, indicating that this is an important mycobacterial-susceptibility gene in humans and confirming the usefulness of this mouse model in the study of human infectious disease susceptibility.

Int J Antimicrob Agents, 1999 Oct, 13(2), 131 - 2
Salmonella meningitis and multiple cerebral abscesses in an infant; Workman MR et al.; The history of a 4-week-old infant with meningitis and multiple cerebral abscesses caused by Salmonella enteritidis is reported . Management included successful treatment with a prolonged course of antibiotics, including ciprofloxacin, neurosurgical drainage and long-term immunoglobulin supplements . No adverse effects of joint toxicity were detected.

Pol J Pharmacol, 1999 Jul-Aug, 51(4), 331 - 9
Submandibular gland peptide-T (SGP-T) modulates ventricular function in response to intravenous endotoxin; Mathison R et al.; A novel peptide hormone isolated from salivary glands, submandibular gland peptide-T (SGP-T), protects against the enhanced hypotensive response to intravenously administered lipopolysaccharide (LPS; 3.5 mg/kg; Salmonella typhosa) in rats with their submandibular glands removed (sialadenectomy) . In this study, we examined the effects of SGP-T on LPS-provoked perturbations of heart function . Sialadenectomy did not alter basal heart function, although the sialadenectomized rats exhibited more pronounced reductions in ventricular peak systolic pressure (VPSP), ventricular pressure at max dP/dt (Pmax dP/dt), and maximum ventricular negative dP/dt (-dP/dt) relative to unoperated controls following LPS challenge . These changes were primarily due to changes in afterload (blood pressure) . However, in sialadenectomized rats LPS-induced changes in Pmax -dP/dt (ventricular pressure at maximum -dP/dt) did not correlate with changes in VPSP, which suggests that sialadenectomy may alter the systolic component of the heart beat . The peptide SGP-T, at doses of 1 and 3.5 microg/kg, corrected Pmax -dP/dt and all other endotoxin-induced changes in heart function . Since Pmax -dP/dt is a measure of relaxation during diastole, the submandibular glands appear to play a role in protecting the heart against the adverse effects of acute endotoxin administration on ventricular relaxation . These effects of the submandibular glands may be mediated by the release of the peptide SGP-T.

Mutat Res, 1999 Nov 29, 430(1), 37 - 45
The aromatic amine carcinogens o-toluidine and o-anisidine induce free radicals and intrachromosomal recombination in Saccharomyces cerevisiae; Brennan RJ et al.; Aniline-based aromatic amine carcinogens are poorly detected in short-term mutagenicity assays such as the Salmonella reverse mutation (Ames) assay . More information on the mechanism of toxicity of such Salmonella-negative carcinogens is needed . Aniline and o-toluidine are negative in the Ames assay, but induce deletions (DEL) due to intrachromosomal recombination in Saccharomyces cerevisiae with an apparent threshold . We show here that the DEL assay also detects the genotoxic activity of another aromatic amine carcinogen, o-anisidine, which is also negative in the Salmonella assay . We also show that the DEL assay distinguishes between o-anisidine and its non-carcinogenic structural analog 2, 4-dimethoxyaniline . We have investigated whether the ability of the DEL assay to detect the carcinogens and to distinguish between the carcinogen/non-carcinogen pair is linked to rises in intracellular free radical species following exposure to the carcinogens . Toxicity induced by all three compounds was reduced in the presence of the free radical scavenger and antioxidant N-acetyl cysteine, recombination induced by o-anisidine and o-toluidine was also reduced by N-acetyl cysteine . All three compounds induced oxidation of the free radical-sensitive reporter compound dichlorofluorescin diacetate . Superoxide dismutase-deficient strains, however, were hypersensitive to cytotoxicity induced by o-toluidine and o-anisidine but not by the non-carcinogen 2,4-dimethoxyaniline, indicating a different potential for generating superoxide radical between the carcinogens and the non-carcinogen analog . The results indicate that the yeast DEL assay is a useful tool for investigating the genotoxic activity of aromatic amine carcinogens.

Vaccine, 2000 Jan 6, 18(11-12), 1140 - 5
Vaccination of chickens with a temperature-sensitive mutant of Salmonella enteritidis; Cerquetti MC et al.; One-day old chickens were inoculated with temperature-sensitive mutant E/1/3 of S . enteritidis . Two routes of inoculation were used: oral and intraperitoneal (ip) . One group of chickens were given two oral inoculations (oral-oral) . A second group received two ip inoculations (ip-ip) . A third group received the first dose orally and the second ip (oral-ip) and the fourth group was given the first dose ip and the second dose orally (ip-oral) . The vaccine strain was safe even when inoculated at high doses, and induced strong protection against virulent S . enteritidis strain after oral challenge . Results show that vaccination with mutant E/1/3 reduced the number of animals shedding the pathogen after challenge . Furthermore, animals immunized oral-oral and oral-ip showed a significant reduction in cecal and spleen colonization by virulent Salmonella.

Rev Sci Tech, 1999 Dec, 18(3), 710 - 8
Emergence of Salmonella enteritidis outbreaks in broiler chickens in the Lebanon: epidemiological markers and competitive exclusion control; Barbour EK et al.; This study investigates the first emergence of Salmonella Enteritidis outbreaks among chickens in the Lebanon and identifies the epidemiological markers of selected recovered Enteritidis strains . In addition, the authors evaluate a competitive exclusion approach to control infection in broiler chickens by Enteritidis organisms which possess the prevalent identified markers . The basic procedure in this investigation involved recording signs and lesions in eleven broiler chicken flocks on eleven farms, and culturing livers, spleens, and caeca of ten randomly selected birds per flock for Salmonella isolation and serotyping . Furthermore, culturing for Salmonella and serotyping was attempted from the livers, spleens, caeca and oviduct swabs of ten hens in four broiler breeder flocks which provided hatching eggs for the broilers under study . The identification of epidemiological markers in recovered S . Enteritidis included the determination of drug-resistance patterns and plasmid profiling . The competitive exclusion was evaluated by spraying the microflora on day-old broilers in the hatchery, followed by a controlled oral challenge at three days of age, with 2.85 x 10(5) colony-forming units of S . Enteritidis organisms per bird . Exclusion was evaluated by culturing for S . Enteritidis in anal swabs, spleens, livers, and caeca of individual challenged birds treated with the microflora and in untreated challenged birds . A total of 112 invasive S . Enteritidis strains were recovered on eleven farms from individual organs of broiler chickens with typical signs and lesions of salmonellosis . The prevalent resistance to drugs in such strains was to furaltadone and gentamycin, a marker identified in 93 strains (83%), recovered from nine out of eleven farms . The same resistance pattern was present in S . Enteritidis strains recovered from breeders on one out of four farms . The prevalent plasmid profile in nine S . Enteritidis organisms selected randomly from a pool of 93 strains (one per each of the nine broiler farms) was 14.1 kilobases (kb) and approximately 50.0 kb, a typical pattern to that identified in S . Enteritidis organisms recovered from oviducts of breeders on one out of four breeder farms . The exclusion significantly reduced cumulative mortality in birds of up to 45 days of age by 3.93%, in comparison to that observed in untreated challenged birds (P < 0.05) . At 45 days of age, exclusion resulted in a 15.6% reduction in the percentage infection rate by S . Enteritidis in spleens or livers and a 34.4% reduction in the percentage infection rate of the caeca (P < 0.05).

Rev Sci Tech, 1999 Dec, 18(3), 700 - 9
Representative Salmonella serovars isolated from poultry and poultry environments in Saudi Arabia; al-Nakhli HM et al.; The authors describe the source and prevalence of pathogenic Salmonella serovars among poultry farms in Saudi Arabia . A total of 1,052 (4%) Salmonella isolates were recovered from 25,759 samples of poultry (broilers, layers, broiler breeders and layer breeders) and poultry environments (box liner, litter, drag swab, droppings, mice and feed) were examined bacteriologically between 1988 and 1997 at the Poultry Disease Laboratory at the National Agriculture and Water Research Center in Riyadh . Eleven Salmonella serogroups representing 38 different Salmonella serovars were identified by means of antigenic analysis . The majority of the 276 isolates (26.2%) of Salmonella typed, were recovered from liver, heart and intestines of the broilers and layers . The most prominent Salmonella serogroups isolated were as follows: serogroup C1 (392 isolates, 37.26%), B (289 isolates, 27.47%) and D1 (269 isolates, 25.69%) . However, untypable and multiple serogroups were also encountered, the most frequent isolates serotyped belonged to groups C1 (97 isolates, 24.7%), D1 (86 isolates, 31.9%), and B (71 isolates, 24.6%) . Salmonella Enteritidis (85 isolates, 98.8%), Salmonella Virchow (48 isolates, 57.8%), Salmonella Paratyphi B var . Java (41 isolates, 57.7%) and Salmonella Infantis (30 isolates, 20.6%) were distributed the most widely as all were encountered in poultry and in poultry environments . S . Enteritidis phage type 4 (30 isolates, 35.3%), was the phage type most frequently detected among group D1 phage types, while 39 (45.8%) of the isolates of S . Enteritidis could not be phage typed.

Genes Genet Syst, 1999 Jun, 74(3), 113 - 6
Reevaluation of the promoter structure of the class 3 flagellar operons of Escherichia coli and Salmonella; Ide N et al.; Flagellar class 3 operons of Escherichia coli and Salmonella are transcribed by RNA polymerase containing sigma 28 . The consensus sequence of the sigma 28-dependent promoters was believed to be TAAA N15 GCCGATAA . In this study, we found that the E . coli genome contains a large number of sequences homologous to this consensus . However, we showed that they do not always exert a sigma 28-dependent promoter activity . We compare more carefully the sequences of the class 3 flagellar promoters and propose a revised structure of the sigma 28-dependent promoters as TAAAGTTT N11 GCCGATAA.

J Trop Pediatr, 1999 Oct, 45(5), 287 - 90
Typhoid hepatitis in children; Shetty AK et al.; Liver involvement is commonly observed in patients with typhoid fever . However, a hepatitis-like picture with fever and jaundice is unusual and infrequently reported in the paediatric literature . Our aim was to characterize the clinical picture, biochemical features, and prognosis of typhoid hepatitis . One hundred cases of typhoid fever (age 0 to 12 years), proven by positive blood cultures to Salmonella typhi, were studied with special reference to hepatic dysfunction . Of these, eight patients were found to have hepatitis during the course of their illness . All had high fever, tender hepatomegaly, elevated serum bilirubin (in the range of 2.5-5.8 mg/dl), and elevated serum alanine transaminase levels (in the range 100-620 IU/l) . All the eight patients showed complete clinical and biochemical recovery in response to appropriate antibiotics . The clinical picture of typhoid hepatitis frequently mimics acute viral hepatitis . In tropical areas, the differential diagnosis of a child presenting with fever and jaundice should include typhoid hepatitis.

Clin Infect Dis, 1999 Oct, 29(4), 862 - 8
Aortitis due to Salmonella: report of 10 cases and comprehensive review of the literature; Soravia-Dunand VA et al.; We describe ten cases of aortitis due to Salmonella that were treated at the University of Toronto-affiliated Hospitals between 1978 and 1997 . Predisposing conditions included hypertension, diabetes mellitus, and myelodysplastic syndrome . Main presenting symptoms were fever and abdominal and back pain . The most frequent site involved was the abdominal aorta, followed by the thoracic aorta . All but one patient were treated with intravenous bactericidal antibiotics; seven also underwent surgery, four with axillobifemoral grafts and three with in situ grafts . Four of seven patients died within 1 month of the surgical procedure (three patients with in situ grafts and one patient with axillobifemoral graft) . We also reviewed the pathogenesis, clinical and laboratory characteristics, and treatment of 140 cases of aortitis due to Salmonella reported in the literature since 1948 . The use of bactericidal antibiotics, together with early surgical intervention and long-term suppressive antibiotic therapy, has led to improved survival.

J AOAC Int, 1999 Nov-Dec, 82(6), 1334 - 9
Isolation of chloramphenicol from whole eggs by supercritical fluid extraction with in-line collection; Pensabene JW et al.; Egg consumption, at more than 65 billion per year in the United States, represents a potentially significant source of exposure to drug residues, particularly if the laying hens are treated with antimicrobial compounds or fed a diet containing medicated feed . Residues resulting from the use of chloramphenicol (CAP) is especially problematic if this compound is not used in accordance with national registration, e.g., for the control of Salmonella microorganisms in poultry . The most commonly used methods for the determination of CAP in biological samples require the use of large amounts of organic solvent . As a result, a less solvent intensive supercritical fluid extraction (SFE) method was developed for CAP in whole chicken eggs, and the results were compared with those for a solvent extraction procedure . In the SFE method, the egg sample is extracted with supercritical CO2 (without a modifier) at 10,000 psi (680 bar), 80 degrees C, and an expanded gas flow rate of 3.0 L/min to a total volume of 150 L . The CAP is trapped in-line on a Florisil sorbent bed . The CAP is eluted post-SFE by using the liquid chromatographic mobile phase solvent (water-methanol), and determined on a C8 column with ultraviolet detection at 280 nm . Recovery from eggs fortified at the 10 ppb level (n = 6) was 81.2 +/- 4.3% . To obtain eggs containing incurred CAP, hens were given a single daily dose of 75 mg CAP (orally by gelatin capsule) for 2 consecutive days, and the eggs were collected over a 12-day period . The mean value for "normally incurred" CAP in the eggs (n = 17) analyzed by SFE ranged from none detected to 174.5 ppb, with an overall mean of 60.5 ppb, compared with a mean of 60.4 ppb for the solvent extraction method . No significant difference in results was found between methods . However, the SFE method is more rapid, uses less solvent, and gives recoveries similar to those for the solvent extraction method, making it ideal for regulatory monitoring.

Teratog Carcinog Mutagen, 1999, 19(6), 403 - 13
Inhibitory effect of propolis and bee venom on the mutagenicity of some direct- and indirect-acting mutagens; Varanda EA et al.; The antimutagenic effect of ethanolic extract of propolis (EEP) and honeybee (Apis mellifera) venom, both collected in the State of Sao Paulo, Brazil, was assessed by the Salmonella/microsome assay upon direct- and indirect-acting mutagens . EEP had inhibitory effect (in an ascending order) on the mutagenicity power of daunomycin (TA102), benzo(a)pyrene (TA100), and aflatoxin B(1)(TA98) and the venom acted against the mutagenicity of 4-nitro-o-phenylenediamine (TA98) and daunomycin (TA102) . Teratogenesis Carcinog . Mutagen . 19:403-413, 1999 .

J Immunol, 1999 Dec 15, 163(12), 6718 - 24
Expression and regulation of the human beta-defensins hBD-1 and hBD-2 in intestinal epithelium; O'Neil DA et al.; The intestinal epithelium forms a physical barrier to limit access of enteric microbes to the host and contributes to innate host defense by producing effector molecules against luminal microbes . To further define the role of the intestinal epithelium in antimicrobial host defense, we analyzed the expression, regulation, and production of two antimicrobial peptides, human defensins hBD-1 and hBD-2, by human intestinal epithelial cells in vitro and in vivo . The human colon epithelial cell lines HT-29 and Caco-2 constitutively express hBD-1 mRNA and protein but not hBD-2 . However, hBD-2 expression is rapidly induced by IL-1alpha stimulation or infection of those cells with enteroinvasive bacteria . Moreover, hBD-2 functions as a NF-kappaB target gene in the intestinal epithelium as blocking NF-kappaB activation inhibits the up-regulated expression of hBD-2 in response to IL-1alpha stimulation or bacterial infection . Caco-2 cells produce two hBD-1 isoforms and a hBD-2 peptide larger in size than previously described hBD-2 isoforms . Paralleling the in vitro findings, human fetal intestinal xenografts constitutively express hBD-1, but not hBD-2, and hBD-2 expression, but not hBD-1, is up-regulated in xenografts infected intraluminally with Salmonella . hBD-1 is expressed by the epithelium of normal human colon and small intestine, with a similar pattern of expression in inflamed colon . In contrast, there is little hBD-2 expression by the epithelium of normal colon, but abundant hBD-2 expression by the epithelium of inflamed colon . hBD-1 and hBD-2 may be integral components of epithelial innate immunity in the intestine, with each occupying a distinct functional niche in intestinal mucosal defense.

Immunol Rev, 1999 Oct, 171, 5 - 26
Live attenuated Salmonella: a paradigm of mucosal vaccines; Sirard JC et al.; Two key steps control immune responses in mucosal tissues: the sampling and transepithelial transport of antigens, and their targeting into professional antigen-presenting cells in mucosa-associated lymphoid tissue . Live Salmonella bacteria use strategies that allow them to cross the epithelial barrier of the gut, to survive in antigen-presenting cells where bacterial antigens are processed and presented to the immune cells, and to express adjuvant activity that prevents induction of oral tolerance . Two Salmonella serovars have been used as vaccines or vectors, S . typhimurium in mice and S . typhi in humans . S . typhimurium causes gastroenteritis in a broad host range, including humans, while S . typhi infection is restricted to humans . Attenuated S . typhimurium has been used successfully in mice to induce systemic and mucosal responses against more than 60 heterologous antigens . This review aims to revisit S . typhimurium-based vaccination, as an alternative to S . typhi, with special emphasis on the molecular pathogenesis of S . typhimurium and the host response . We then discuss how such knowledge constitutes the basis for the rational design of novel live mucosal vaccines.

Lett Appl Microbiol, 1999 Oct, 29(4), 269 - 72
Rapid detection of Salmonella in field samples by nested polymerase chain reaction; Rychlik I et al.; A simple and universal protocol for the rapid detection of Salmonella spp . in various samples using nested polymerase chain reaction (PCR) was developed . The protocol takes advantage of the rapid purification and concentration of Salmonella by centrifugation onto a layer of 60% sucrose solution . DNA was released by treatment with proteinase K and Triton X-100 . Even without pre-enrichment, the detection limit for the nested PCR was 10(5) CFU g-1 of faeces . After pre-enrichment, it was possible to detect Salmonella in faeces where their original concentration was approximately 10(2) CFU g-1 of faeces and in meat samples, it was possible to detect Salmonella in samples where their original concentration was less than 10 cells g-1 of minced meat.

J Appl Microbiol, 1999 Oct, 87(4), 536 - 9
Salmonella infection in children from the wastewater-spreading zone of Marrakesh city (Morocco); Aiat Melloul A et al.; The available circumstantial evidence gained from epidemiological and microbiological investigations suggests that the use of untreated wastewater causes an excess of Salmonella infection among children living in El Azzouzia (the wastewater-spreading area of Marrakesh city, Morocco) compared with those from a control area that does not practice sewage irrigation (Sidi Moussa) . The prevalence in the exposed group (32.56%) was significantly (P < 0 . 001) higher than for the control group (1.14%) . Serogroups B and C were the most commonly isolated . Boys were at greater risk (37.61%) of contracting Salmonella infection than girls (26.66%) . Age-specified rates showed that children of less than 10 years old were infected at a higher rate than older children in the area (exposed group), with 40.32% and 19.72% rates of infection, respectively . Crop irrigation with untreated wastewater caused a significantly higher rate of infection with Salmonella in the children of agricultural workers (39.33%) than in the children of non-agriculturists (24.58%).

Antimicrob Agents Chemother, 1999 Dec, 43(12), 3018 - 21
Genetic characterization of antimicrobial resistance in Canadian isolates of Salmonella serovar Typhimurium DT104; Ng LK et al.; PCR was used to identify antibiotic resistance determinants in 31 Canadian Salmonella serovar Typhimurium DT104 isolates . Genes encoding resistance to ampicillin (pse1 or blaP1), chloramphenicol (pasppflo-like), streptomycin-spectinomycin (aadA2), sulfonamide (sulI), and tetracycline {tet(G)} were mapped to a 13-kb region of DNA of one isolate . Two copies of sulI were identified and mapped to the 3' end of either pse1 or aadA2 integrons . The two integrons were separated by the pasppflo-like gene and the tet(G) gene . The kanamycin resistance determinant (aphA-1) was present on a 2.0-MDa plasmid (five isolates) or on the chromosome (three isolates).

Antimicrob Agents Chemother, 1999 Dec, 43(12), 2925 - 9
Incidence and characterization of integrons, genetic elements mediating multiple-drug resistance, in avian Escherichia coli; Bass L et al.; Antibiotic resistance among avian bacterial isolates is common and is of great concern to the poultry industry . Approximately 36% (n = 100) of avian, pathogenic Escherichia coli isolates obtained from diseased poultry exhibited multiple-antibiotic resistance to tetracycline, oxytetracycline, streptomycin, sulfonamides, and gentamicin . Clinical avian E . coli isolates were further screened for the presence of markers for class 1 integrons, the integron recombinase intI1 and the quaternary ammonium resistance gene qacEDelta1, in order to determine the contribution of integrons to the observed multiple-antibiotic resistance phenotypes . Sixty-three percent of the clinical isolates were positive for the class 1 integron markers intI1 and qacEDelta1 . PCR analysis with the conserved class 1 integron primers yielded amplicons of approximately 1 kb from E . coli isolates positive for intI1 and qacEDelta1 . These PCR amplicons contained the spectinomycin-streptomycin resistance gene aadA1 . Further characterization of the identified integrons revealed that many were part of the transposon Tn21, a genetic element that encodes both antibiotic resistance and heavy-metal resistance to mercuric compounds . Fifty percent of the clinical isolates positive for the integron marker gene intI1 as well as for the qacEDelta1 and aadA1 cassettes also contained the mercury reductase gene merA . The correlation between the presence of the merA gene with that of the integrase and antibiotic resistance genes suggests that these integrons are located in Tn21 . The presence of these elements among avian E . coli isolates of diverse genetic makeup as well as in Salmonella suggests the mobility of Tn21 among pathogens in humans as well as poultry.

Microbios, 1999, 100(395), 41 - 6
Isolation, identification and analysis of antibacterial activity of soil streptomycetes isolates from north Jordan; Saadoun I et al.; A total of 90 different Streptomyces isolates were recovered from 36 soil samples and assessed for their antibacterial activity . Nine isolates were identified by the absence of an aerial mycelium . The rest were grouped into six colour series, namely grey, white, yellow, green, red and polymorphic colours (pink, orange or violet) with total numbers of 29, 18, 14, 8, 3 and 9, respectively . The isolates (68%) showed a reverse side culture pigmentation, 30% produced melanin and 25% produced other soluble pigments . Isolates (48%) were characterized by flexuous spore chains, 21% with spiral and 10% for each of the rectus and retinaculum apertum arrangement . The antibiotic activity against a wide range of bacteria was exhibited by 54% of the isolates which were effective against Bacillus subtilis (57%), Staphylococcus aureus (47%), Escherichia coli (24%), Klebsiella spp (16%), and Shigella spp (12%) . The lowest activity (8%) was exhibited against Pseudomonas spp and Salmonella spp . The antibacterial activity of the isolates was divided into four groups according to the diameter of the inhibition zone produced . Groups 3 and 4 with larger inhibition zones indicated their potential as a possible source of novel antibiotics.

Acta Microbiol Pol, 1999, 48(2), 131 - 40
Application of Salmonella strains with altered nitroreductase and O-acetyltransferase activities to the evaluation of the mutagenicity of airborne particles; Adamiak W et al.; The Ames test was applied to evaluation of the mutagenicity of month's samples of airborne particles from the center of Wroclaw (SW Poland) collected in August and December 1997 . The strains used for the study were TA 98, TA 100 and their derivatives: TA 98 NR, YG 1021, YG 1024, YG 1026, YG 1029, YG 1041, YG 1042 . Both studied samples were mutagenic for almost all tested strains, with the exception of the August sample which did not influence the strain TA 100 without the metabolic activation with the S9 fraction . The December sample exhibited higher genotoxic activity than the August sample . Mutagenicity ratios of the strains with reduced nitroreductase and O-acetyltransferase activities were higher, and of the strain without the nitroreductase--lower than those of the parent strains . This indicates that nitro and amino derivatives of PAHs are responsible for the significant proportion of total mutagenicity of the studied samples of particulates . Metabolic activation with the S9 fraction caused the increase of the mutagenic activity of the samples, which indicates the presence of promutagens . The GC-MS analysis revealed the presence of known indirect mutagens from the PAHs group.

J Med Chem, 1999 Nov 4, 42(22), 4640 - 9
3-O-Desacyl monophosphoryl lipid A derivatives: synthesis and immunostimulant activities; Johnson DA et al.; The synthesis of a series of novel analogues of lipid A, the active principle of lipopolysaccharide, is reported . In these compounds, the 1-O-phosphono and (R)-3-hydroxytetradecanoyl moieties of native Salmonella minnesota R595 lipid A have been replaced with hydrogen and the length of the normal fatty acyl residues has been systematically varied . Normal fatty acid chain length in the 3-O-desacyl monophosphoryl lipid A (MLA) series is shown to be a critical determinant of iNOS gene expression in activated mouse macrophages and the induction of proinflammatory cytokines in human peripheral monocytes . Examination of pyrogenicity in rabbits and lethal toxicity in D-galactosamine-treated mice shows that toxic effects in the MLA series can be ameliorated by modifying fatty acid chain length . When used as an adjuvant for tetanus toxoid vaccines, certain MLA derivatives enhance the production of tetanus toxoid-specific antibodies in mice.

J Microbiol Methods, 1999 Dec, 39(1), 33 - 43
Isolation and detection of Listeria spp, Salmonella spp and Yersinia spp using a simultaneous enrichment step followed by a surface adhesion immunofluorescent technique; Cloak OM et al.; The use of a rapid surface adhesion immunofluorescent (SAIF) technique for the isolation of three pathogens using a single enrichment step from broth and enriched meat cultures was investigated . Buffered peptone water (BPW, 225 ml) was inoculated with Listeria monocytogenes, Salmonella enteritidis and Yersinia enterocolitica to a level of 10 cfu ml(-1) and incubated overnight at 30 degrees C . Minced beef samples (25 g) were inoculated with the three pathogens to a level of 100 cfu g(-1) and incubated overnight at 30 degrees C in BPW (225 ml) . Pathogens were isolated by surface adhesion to a polycarbonate membrane which was immersed in the enriched culture . The pathogens were detected using membrane counts (rinse and immunofluorescent) and standard plate counts . It was noted that the attachment of the three pathogens to the membrane was considerably enhanced when compared with single inoculum experiments and the reasons and implications of this for the rapid method are discussed . A small selection of naturally contaminated retail samples (n = 60) was tested for the presence of L . monocytogenes and S . enteritidis using a simultaneous enrichment step with SAIF detection and a standard cultural method of detection . A good correlation was found between both methods for L . monocytogenes (r2 = 0.91, RSD = 0.26) and S . enteritidis (r2 = 0.89, RSD = 0.28) . This indicates that simultaneous analysis of these two pathogens could be carried out using the SAIF assay.

MMWR Morb Mortal Wkly Rep, 1999 Nov 12, 48(44), 1009 - 13
Reptile-associated salmonellosis--selected states, 1996-1998; Identification of Shigella serotypes by restriction of amplified O-antigen gene cluster; Unite des enterobacteries, Inserm 389, Institut Pasteur, Paris, FranceDue to the scarcity of distinctive biochemical reactions for differentiation of Shigella-Escherichia coli, antigenic analysis has long been used for identification and typing of Shigella isolates . Nevertheless, several intra- and interspecific cross-reactions have been reported to disturb serotyping assays . Shigella serotyping is also occasionally affected by the transition from the smooth (S) form to the rough (R) form . Thus, there is a need for the development of novel robust and discriminating methods for Shigella identification and typing . Characteristically, all genes specifically involved in O-antigen synthesis are clustered in E . coli, Shigella, and Salmonella . Published oligonucleotide sequences complementary to JUMPstart and gene gnd, the conserved flanking sequences upstream and downstream of O-antigen gene clusters, were used to amplify the O-antigen gene cluster of representative strains of each Shigella serotype . A unique, amplified fragment was generally observed for each serotype (size ranging from 6 kbp to 17 kbp) . Clearly identifiable and reproducible patterns were obtained for each serotype after MboII digestion of the products, except for S . boydii 12 which showed two distinct patterns, and S . flexneri serotypes 1 to 5 and X and Y which showed a single pattern . A database was built with the Taxotron package allowing automated identification of clinical Shigella isolates to all known serotypes.

Farmaco, 1999 Oct 30, 54(10), 643 - 7
Antimicrobial and genotoxic activities of N-(2-hydroxyethyl)-1,2-benzisothiazol-3(2H)-thione carbamic esters; Zani F et al.; The antimicrobial properties of N-(2-hydroxyethyl)-1,2-benzisothiazol-3(2H)-thione (1a,b) and its carbamic esters 2a,b-6a,b were tested in vitro against Gram positive and Gram negative bacteria, yeasts and dermatophytes . All compounds markedly inhibit the growth of Gram positive bacteria exhibiting MIC values ranging from 1.25 to 10 micrograms/ml . A strong antifungal activity is exerted against dermatophytes with MICs, in general, between 0.7 and 12 micrograms/ml . Structure-activity relationship studies show that these compounds are, in most cases, more effective than the corresponding benzisothiazolone analogues 7-12 . None of the tested compounds shows genotoxic properties by Bacillus subtilis rec-assay and Salmonella-microsome test.

J Biol Chem, 1999 Dec 3, 274(49), 35129 - 38
The activity of a putative polyisoprenol-linked sugar translocase (Wzx) involved in Escherichia coli O antigen assembly is independent of the chemical structure of the O repeat; Feldman MF et al.; During O antigen lipopolysaccharide (LPS) synthesis in bacteria, transmembrane migration of undecaprenylpyrophosphate (Und-P-P)-bound O antigen subunits occurs before their polymerization and ligation to the rest of the LPS molecule . Despite the general nature of the translocation process, putative O-antigen translocases display a low level of amino acid sequence similarity . In this work, we investigated whether complete O antigen subunits are required for translocation . We demonstrate that a single sugar, GlcNAc, can be incorporated to LPS of Escherichia coli K-12 . This incorporation required the functions of two O antigen synthesis genes, wecA (UDP-GlcNAc:Und-P GlcNAc-1-P transferase) and wzx (O-antigen translocase) . Complementation experiments with putative O-antigen translocases from E . coli O7 and Salmonella enterica indicated that translocation of O antigen subunits is independent of the chemical structure of the saccharide moiety . Furthermore, complementation with putative translocases involved in synthesis of exopolysaccharides demonstrated that these proteins could not participate in O antigen assembly . Our data indicate that recognition of a complete Und-P-P-bound O antigen subunit is not required for translocation and suggest a model for O antigen synthesis involving recognition of Und-P-P-linked sugars by a putative complex made of Wzx translocase and other proteins involved in the processing of O antigen.

J Zoo Wildl Med, 1999 Sep, 30(3), 383 - 8
Salmonella spp . survey of captive rhinoceroses in U.S . zoological institutions and private ranches; Kenny DE; A survey was mailed to 72 institutions in the USA requesting information on Salmonella spp . cultures in black rhinoceroses (Diceros bicornis), white rhinoceroses (Ceratotherium simum), and Indian rhinoceroses (Rhinoceros unicornis) . Sixty-one institutions responded (85% return rate), with seven reporting positive cultures (11% prevalence rate; 10% if survey nonresponders had negative cultures) . There were 17 positive cultures from 16 different animals, with nine different serotypes of Salmonella and 2 additional cultures identified to the group level.

Int J Food Microbiol, 1999 Oct 15, 51(2-3), 191 - 6
Detection and quantification of Salmonella in pure cultures using 5'-nuclease polymerase chain reaction; Nogva HK et al.; Advances in detection and quantification assays based on nucleic acids conceivably will revolutionize the ability to quickly and specifically detect and quantify microorganisms in foods . Among these assays, the polymerase chain reaction (PCR) assay and the TaqMan PCR Detection System (Perkin-Elmer) probably are among the most promising . Since a 5'-nuclease PCR renders possible the automated and direct detection and quantification of PCR products (Holland et al., 1991 . Proc . Natl . Acad . Sci . USA 88, 7276-7280), microorganisms in foods can be detected and quantified indirectly within a few hours through analysis of the microbial DNA or RNA sequences present . In the present report we have adapted a 5'-nuclease-based kit for the quantification of Salmonella.

Int J Food Microbiol, 1999 Oct 15, 51(2-3), 113 - 22
Detection of Salmonella enteritidis by reverse transcription-polymerase chain reaction (PCR); Szabo EA et al.; A reverse transcription-polymerase chain reaction (RT-PCR) method was developed for detecting mRNA from the sefA gene of Salmonella enteritidis . Detection of target mRNA was examined from cells grown in buffered peptone water at different temperatures (37, 25 and 15 degrees C) and pH (5.5, 7.2 and 8.5) . The results revealed that the levels of transcription of the sefA gene differed depending upon the physiological state of the cells . This affected the sensitivity of the RT-PCR assay . When the assay was evaluated for the detection of S . enteritidis PT4 in artificially contaminated minced beef and whole egg samples, an enrichment step was used (buffered peptone water, pH 7.2, 37 degrees C, 16 h) to increase the sensitivity of the assay . In the presence of the normal background flora of each food type, it was possible to detect ten cells of S . enteritidis PT4 after a 16-h enrichment using the RT-PCR assay, with a total testing time of 28 h . Unlike the PCR test for the sefA gene that was tested in parallel, the RT-PCR assay did not detect nonviable (heat-inactivated) S . enteritidis PT4 cells . The results supported the usefulness of RT-PCR as a method for the detection of viable microorganisms.

Int J Food Microbiol, 1999 Oct 15, 51(2-3), 85 - 94
Evaluation of culture enrichment procedures for use with Salmonella detection immunoassay; Huang H et al.; To design efficient culture strategies for use with immunoassays to detect Salmonella in food, the growth of these organisms was investigated according to the Bacteriological Analytical Manual (BAM) and enrichment-immunoassay (EI) culture procedures . The cultures were further evaluated using a commercial enzyme-linked immunosorbent assay (ELISA) kit . The BAM procedure includes pre-enrichment in nutrient broth (NB) for 16 h followed by selective enrichment in either Rappaport-Vassiliadis (RV) or tetrathionate brilliant green (TBG) broth for 16 h . The EI procedure includes pre-enrichment in NB for 4 h, selective enrichment in RV for 16 h and post-enrichment in NB for 4 h . The effects of different incubation times for pre- and post-enrichment, and different culture media for selective enrichment (TBG and RV) and post-enrichment in NB and Brain Heart Infusion broth (BHI) on the growth of the bacteria and ELISA titers in the EI procedure were also investigated . Salmonella enteritidis and S . typhimurium inoculated at different initial concentrations between 0.1 and 35 CFU/ml grew to similar concentrations of 10(7) to 10(8) colony forming unit (CFU)/ml in pure culture and generally 2 to 4 fold lower concentrations (P<0.05) in mixed culture using spiked chicken rinse . In the BAM procedure, the concentration of Salmonella cultured in RV was higher (P<0.01) than that in TBG . The cultures in TBG showed positive results for ELISA, but those in RV were generally negative . In the EI procedure, the ELISA titers from cultures post-enriched in NB or BHI were higher (P<0.01) when TBG, as compared to RV, was used for selective enrichment . Post-enrichment in BHI yielded higher numbers of Salmonella and higher ELISA titers than those in NB (P<0.05) for post-enrichment . This study demonstrated that in both culture procedures small numbers of Salmonella could be increased to at least 10(7) CFU/ml which is detectable by most ELISAs, and that the type of the culture media used may have a significant impact on ELISA results.

Indian J Med Res, 1999 Aug, 110, 47 - 9
Dot-ELISA for detection of Salmonella enterotoxin; Rahman H; Nineteen strains of Salmonella enterica belonging to seven serovars and two strains of S . bongori were investigated for enterotoxin production by the Chinese hamster ovary (CHO) cell assay and Dot-ELISA . All the 19 strains were found to carry stn gene when tested by polymerase chain reaction (PCR) using specific primers for stn sequence . Thirteen strains (68.42%) were found to produce Salmonella enterotoxin (Stn) when tested by the CHO cell assay . Dot-ELISA could detect Stn in 16 strains (84.21%) . Dot-ELISA may be preferred over other assays due to its low cost and simplicity in performance.

Indian J Med Res, 1999 Aug, 110, 43 - 6
Prevalence of enterotoxin gene (stn) among different serovars of Salmonella; Rahman H; The prevalence of Salmonella enterotoxin (stn) gene among different Salmonella serovars by using polymerase chain reaction (PCR) and its status of expression on the Chinese hamster ovary (CHO) cells were investigated . All the 26 strains of Salmonella enterica such as serovars Typhimurium, Enteritidis, Dublin, Typhi, Newport, Weltevreden, Gallinarum, etc . investigated in this study were found to carry stn gene as examined by the PCR and gene probe . However, only a limited number of stn positive strains (34.6%) were found to express phenotypically the Salmonella enterotoxin (Stn) as tested by the CHO cell assay . The strains of S . bongori were found to be negative for Stn production both genotypically and phenotypically.

J Pediatr Orthop, 1999 Nov-Dec, 19(6), 710 - 4
Salmonella typhi spondylitis; Govender S et al.; We report on five patients with Salmonella typhi spondylitis who were immunologically normal and had no prodromal gastrointestinal illness . The diagnosis was confirmed on blood cultures, Widal test, and needle biopsy of the spine . Appropriate antibiotic treatment resulted in a favorable outcome.

Biochim Biophys Acta, 1999 Oct 8, 1455(2-3), 387 - 402
Chlamydial lipopolysaccharide; Kosma P; Chlamydiae are obligatory intracellular parasites which are responsible for various acute and chronic diseases in animals and humans . The outer membrane of the chlamydial cell wall contains a truncated lipopolysaccharide (LPS) antigen, which harbors a group-specific epitope being composed of a trisaccharide of 3-deoxy-D-manno-oct-2-ulosonic (Kdo) residues of the sequence alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo . The chemical structure was established using LPS of recombinant Escherichia coli and Salmonella enterica strains after transformation with a plasmid carrying the gene encoding the multifunctional chlamydial Kdo transferase . Oligosaccharides containing the Kdo region attached to the glucosamine backbone of the lipid A domain have been isolated or prepared by chemical synthesis, converted into neoglycoproteins and their antigenic properties with respect to the definition of cross-reactive and chlamydia-specific epitopes have been determined . The low endotoxic activity of chlamydial LPS is related to the unique structural features of the lipid A, which is highly hydrophobic due to the presence of unusual, long-chain fatty acids.

Mutagenesis, 1999 Nov, 14(6), 613 - 20
Antimutagenic effects of centchroman--a contraceptive and a candidate drug for breast cancer in multiple mutational assays; Giri AK et al.; Centchroman (CC), a non-steroidal oral contraceptive and a candidate drug for breast cancer, has been reported to exhibit partial to complete remission of lesions in 40.5% of breast cancer patients . The potent anti-oestrogenic activity, negligible side-effects and anti-breast cancer activity of CC prompted us to evaluate the antimutagenic effects of this compound in a bacterial mutagenicity assay and CHO/HPRT and AS52/GPT mutation assays in vitro and in vivo in female Swiss albino mice as measured by both sister chromatid exchange (SCE) and chromosome aberrations (CA) against three known positive mutagen compounds, dimethylbenz{a}anthracene (DMBA), cyclophosphamide (CP) and mitomycin C (MMC) . Antimutagenicity assays in Salmonella strains TA97a, TA100, TA98 and TA102 were carried out against commonly used known positive mutagens, sodium azide, 4-nitro-o-phenylenediamine, cumine hydroperoxide, 2-aminofluorene and danthron . A significantly reduced number of bacterial histidine revertant colonies was observed in the plates treated with 0.1, 1, 5 and 10 microg/plate CC and a positive compound when compared with bacterial plates treated with the respective positive compound alone . Ethyl methanesulfonate (EMS), a commonly used positive mutagen for CHO/HPRT and AS52/GPT gene mutation assays, was used for antimutagenicity assay in these cells . CC exhibited protective effects against the mutagenicity of EMS in these two mammalian cell mutation assays, CHO/HPRT and AS52/GPT . In the in vivo studies, pretreatment with CC reduced DMBA-induced SCE and CA and CP- and MMC-induced CA when compared with the group treated only with the positive compounds . These results indicate that CC can reduce the mutagenic effects of known genotoxic compounds.

Mutagenesis, 1999 Nov, 14(6), 533 - 40
Genotoxic effects of heterocyclic aromatic amines in human derived hepatoma (HepG2) cells; Knasmuller S et al.; In order to study the mutagenic effects of heterocyclic aromatic amines (HAAs) in cells of human origin, five compounds, namely 2-amino-3-methyl-imidazo{4,5-f}quinoline (IQ), 2-amino-3, 4-dimethyl-imidazo{4,5-f}quinoline (MeIQ), 2-amino-3, 8-dimethyl-imidazo{4,5-f}quinoxaline (MeIQx), the pyridoimidazo derivative 2-amino-1-methyl-6-phenylimidazo{4,5-b}pyridine (PhIP) and 3-amino-1,4-dimethyl-5H-pyrido{4,3-b}indole (Trp-P-1), were tested in micronucleus (MN) assays with a human derived hepatoma (HepG2) cell line . All HAAs caused significant, dose-dependent effects . The activities of IQ, MeIQ, MeIQx and PhIP were similar (lowest effective concentrations 25-50 microM), whereas Trp-P-1 was effective at a dose of >/=2.1 microM . In addition, the HAAs were tested in MN assays with Chinese hamster ovary (CHO) cells and in Salmonella strain YG1024 using HepG2 cell homogenates as an activation mix . In the CHO experiments, positive results were obtained with Trp-P-1 and PhIP, whereas the other compounds were devoid of activity under all experimental conditions . The discrepancy in the responsivity of the two cell lines is probably due to differences in their acetylation capacity: enzyme measurements with 2-aminofluorene as a substrate revealed that the cytosolic acetyltransferase activity in the HepG2 cells is approximately 40-fold higher than that of the CHO cells . In the bacterial assays all five HAAs gave positive results but the ranking order was completely different from that seen in the HepG2/MN experiments (IQ > MeIQ > Trp-P-1 >/= MeIQx >> PhIP) and the mutagenic potencies of the various compounds varied over several orders of magnitude . The order obtained in bacterial tests with rat liver S9 mix was more or less identical to that seen in the tests with HepG2 cell homogenates but the concentrations of the amines required to give positive results were in general substantially lower (10(-5)-10(-1) microM) . Overall, the results of the present study indicate that MN/HepG2 tests might reflect the mutagenic effects of HAAs more adequately than other in vitro mammalian cell systems due to the presence of enzymes involved in the metabolic conversion of the amines.

Microb Drug Resist, 1999 Fall, 5(3), 195 - 200
Harmonization of antibiotic susceptibility testing for Salmonella: results of a study by 18 national reference laboratories within the European Union-funded Enter-net group; Threlfall EJ et al.; For the effective surveillance of antimicrobial drug resistance within Salmonella organisms from humans, harmonization of methods used for sensitivity testing by laboratories responsible for the typing of such organisms is essential . A study of resistance or sensitivity to a panel of 11 antimicrobials by the Enter-net international surveillance network was therefore undertaken . There are 18 national Salmonella reference laboratories within this European Union-funded network . Forty-eight strains of Salmonella enterica were distributed to each laboratory for testing for resistance or sensitivity to ampicillin, cefotaxime, chloramphenicol, gentamicin, kanamycin, streptomycin, sulfonamides, tetracyclines, trimethoprim, nalidixic acid, and ciprofloxacin . Over 8,500 tests were assessed involving disk diffusion (DD), agar breakpoint (BP), or full minimum inhibitory concentration (MIC) . Results indicated that whichever method was used, there was a high degree of concordance for the detection of resistance to most antimicrobials; only for decreased sensitivity to ciprofloxacin was there substantial nonconcordance . Because all isolates with decreased sensitivity to ciprofloxacin were resistant to nalidixic acid, it is suggested that, if required, MICs to ciprofloxacin could be determined for isolates resistant to nalidixic acid . For the detection of sensitivity, the main area of nonconcordance was in the detection of sensitivity to streptomycin . With the exception of decreased sensitivity to ciprofloxacin, we are confident that a database of antimicrobial susceptibilities can now be established and harmonized antibiogram data for Salmonella can now be exchanged for national Salmonella reference laboratories within the European Union.

J Agric Food Chem, 1999 Jan, 47(1), 221 - 30
Inhibitory effects of beer and other alcoholic beverages on mutagenesis and DNA adduct formation induced by several carcinogens; Arimoto-Kobayashi S et al.; The possibility that beer and other alcoholic beverages could be antimutagenic against the heterocyclic amines (HAs), a group of carcinogens produced on cooking proteinaceous foods, has been explored . In the Salmonella mutation assays, beer showed inhibitory effects against several HAs {preactivated Trp-P-1, Trp-P-2(NHOH), and Glu-P-1(NHOH)} that are directly mutagenic in bacteria . Japanese sake, red and white wines, and brandy were also effective . However, ethyl alcohol alone did not show these effects . The formation of O(6)-methylguanine by N-methyl-N'-nitro-N-nitrosoguanidine in the DNA of Salmonella YG7108 was also inhibited by beer . Nonvolatile beer components were administered orally to CDF(1) mice together with Trp-P-2 . Adducts in the liver DNA were significantly decreased by the beer, as compared to those in controls fed Trp-P-2 only . Although several phenolic compounds known to be present in beer were antimutagenic toward these mutagens, their effects were very small . It was concluded that some yet to be identified component(s) of beer is (are) responsible for this antimutagenicity.

Poult Sci, 1999 Nov, 78(11), 1510 - 7
Hyporesponsiveness of the systemic and mucosal humoral immune systems in chickens infected with Salmonella enterica serovar enteritidis at one day of age; Holt PS et al.; Newly hatched chicks lack immunological maturity, which could compromise their ability to respond to infection by pathogens such as Salmonella enterica serovar enteritidis (S . enteritidis; SE) . A study was conducted in which chicks were infected with a sublethal dose of SE at 1 d posthatch, and the systemic and intestinal immune responses to the challenge were followed over time . Birds infected at this age experienced difficulty in clearing the infection, and 50% of the individual birds remained persistently infected until 23 wk of age . These birds exhibited only a marginal systemic and mucosal humoral immune response to the infection . No response or little response was observed 1 wk postchallenge; responses increased somewhat over time . On many of the sampling times, 50% or more of the culture-positive birds lacked a detectable plasma or intestinal response . Levels of 10(3) to 10(5) SE/g of feces could be found in the intestines of birds eliciting a good IgA response, indicating that, when these birds did respond mucosally, the IgA produced was incapable of clearing the organism once the infection was established . Birds infected during this time also experienced reduced ability to respond to vaccination . Compared with uninfected controls, depressed responsiveness to an S . enteritidis bacterin was observed in infected birds 1 and 2 wk after administration, whereas those individuals receiving an inactivated Newcastle disease vaccine (NDV) experienced a reduced response 4 and 6 wk postvaccination, indicating that the persistent infection affected the ability of the immune system to respond to homologous and heterologous antigens . These results demonstrate that exposure of chickens to SE early in life interferes with the ability of these individuals to respond humorally to the infection and to other antigenic stimuli; such effects can be observed for at least 23 wk.

Infect Immun, 1999 Dec, 67(12), 6424 - 33
Optimization of plasmid maintenance in the attenuated live vector vaccine strain Salmonella typhi CVD 908-htrA; Galen JE et al.; The broad objective of the research presented here is to develop a noncatalytic plasmid maintenance system for the stabilization of multicopy expression plasmids encoding foreign antigens in a Salmonella typhi live-vector vaccine strain such as CVD 908-htrA . We have enhanced the maintenance of expression plasmids at two independent levels . First, we removed dependence upon balanced-lethal maintenance systems that involve catalytic enzymes expressed from multicopy plasmids; we accomplished this through incorporation into expression plasmids of a postsegregational killing system based on the noncatalytic hok-sok plasmid addiction system from the antibiotic resistance factor pR1 . We also included at least one naturally occurring plasmid partition function in our expression plasmids, which eliminates random segregation of these plasmids, thereby enhancing their inheritance and stability; to accomplish this, we incorporated either the par locus from pSC101, the parA locus from pR1, or both . We monitored the stability of optimized expression plasmids within CVD 908-htrA by quantitating expression of a variant of green fluorescent protein (GFPuv) by using flow cytometry . In this report, we demonstrate the utility of this novel plasmid maintenance system in enhancing the stability of our expression plasmids and go on to show that as the copy number of stabilized plasmids increases, the toxicity of GFPuv synthesis also increases . The implications of these observations for the rational design of immunogenic and protective bacterial live vector vaccines are discussed.

Infect Immun, 1999 Dec, 67(12), 6385 - 93
Identification of a putative Salmonella enterica serotype typhimurium host range factor with homology to IpaH and YopM by signature-tagged mutagenesis; Tsolis RM et al.; The genetic basis for the host adaptation of Salmonella serotypes is currently unknown . We have explored a new strategy to identify Salmonella enterica serotype Typhimurium (S . typhimurium) genes involved in host adaptation, by comparing the virulence of 260 randomly generated signature-tagged mutants during the oral infection of mice and calves . This screen identified four mutants, which were defective for colonization of only one of the two host species tested . One mutant, which only displayed a colonization defect during the infection of mice, was further characterized . During competitive infection experiments performed with the S . typhimurium wild type, the mutant was defective for colonization of murine Peyer's patches but colonized bovine Peyer's patches at the wild-type level . No difference in virulence between wild type and mutant was observed when calves were infected orally with 10(10) CFU/animal . In contrast, the mutant possessed a sixfold increase in 50% lethal morbidity dose when mice were infected orally . The transposon in this mutant was inserted in a 2.9-kb pathogenicity islet, which is located between uvrB and yphK on the S . typhimurium chromosome . This pathogenicity islet contained a single gene, termed slrP, with homology to ipaH of Shigella flexneri and yopM of Yersinia pestis . These data show that comparative screening of signature-tagged mutants in two animal species can be used for scanning the S . typhimurium genome for genes involved in host adaptation.

Food Chem Toxicol, 1999 Nov, 37(11), 1113 - 8
Comparison of the cytotoxic and mutagenic potential of liquid smoke food flavourings, cigarette smoke condensate and wood smoke condensate; Putnam KP et al.; Although products of pyrolysis are often cytotoxic and mutagenic, the relationship between the type of material pyrolysed and the toxicity of the resulting pyrolysis products is poorly understood . The objective of this study was to evaluate and compare the cytotoxicity and mutagenicity of several types of common pyrolysis products . The cytotoxicity and mutagenicity of these products were assessed by using neutral red uptake and Ames mutagenicity assays, respectively . The biological activities of four liquid smoke food flavourings (LSF) were compared with two other pyrolysis-derived materials; cigarette smoke condensate (CSC) and a wood smoke condensate (WSC) . Results indicated all of the mixtures exhibited a concentration-dependent cytotoxic response . The CSC and WSC were less cytotoxic than three of the LSFs, but more cytotoxic than one of the brands . The CSC was mutagenic in two Salmonella strains; however, none of the LSFs or WSC was mutagenic using TA98, and only three of the LSFs were positive with TA100 . The six pyrolysis-derived materials evaluated in this study showed differing patterns and magnitudes of cytotoxicity and mutagenicity . These results indicate that the cytotoxicity and mutagenicity of complex mixtures derived from pyrolysis products are affected by the type of material pyrolysed and/or the method used to prepare the mixture . The cytotoxic potential of some commercial smoke flavourings is greater than cigarette smoke condensate and several of the food flavourings are mutagenic in one Salmonella strain.

Mol Microbiol, 1999 Nov, 34(4), 780 - 91
Interaction between the F plasmid TraA (F-pilin) and TraQ proteins; Harris RL et al.; Elaboration of conjugative (F) pili by F+ strains of Escherichia coli requires the activities of over a dozen F-encoded DNA transfer (Tra) proteins . The organization and functions of these proteins are largely unknown . Using the yeast two-hybrid assay, we have begun to analyse binary interactions among the Tra proteins required for F-pilus formation . We focus here on interactions involving F-pilin, the only known F-pilus subunit . Using a library of F tra DNA fragments that contained all the F genes required for F pilus formation in a yeast GAL4 activation domain vector (pACTII), we transformed yeast containing a plasmid (pAS1CYH2traA) encoding a GAL4 DNA-binding domain-F-pilin fusion . Doubly transformed cells were screened for GAL4-dependent gene expression . This screen repeatedly identified only a single Tra protein, TraQ, previously identified as a likely F-pilin chaperone . The F-pilin-TraQ interaction appeared to be specific, as no transcriptional activation was detected in yeast transformants containing pACTIItraQ plasmids and the Salmonella typhi pED208 traA gene cloned in pAS1CYH2 . Two traQ segments isolated in the screen against F-pilin were tested for complementation of a traQ null allele in E . coli . One, lacking the first 11 (of 94) TraQ amino acids, restored DNA donor activity, donor-specific bacteriophage sensitivity and membrane F-pilin accumulation to wild-type levels . The second, lacking the first 21 amino acids, was much less effective in these assays . Both TraQ polypeptides accumulated in E . coli as transmembrane proteins . The longer, biologically active segment was fused to the GAL4 DNA-binding domain gene of pAS1CYH2 and used to screen the tra fragment library . The only positives from this screen identified traA segments . The fusion sites between the traA and GAL4 segments identified the hydrophobic, C-terminal domain IV of F-pilin as sufficient for the interaction . As TraQ is the only Tra protein required for the accumulation of inner membrane F-pilin, the interaction probably reflects a specific, chaperone-like function for TraQ in E . coli . Attempts to isolate an F-pilin-TraQ complex from E . coli were unsuccessful, suggesting that the interaction between the two is normally transient, as expected from previous studies of the kinetics of TraA membrane insertion and processing to F-pilin.

Biomed Environ Sci, 1999 Jun, 12(2), 136 - 43
Comparison of the mutagenicity of exhaust emissions from motor vehicles using leaded and unleaded gasoline as fuel; Yuan D et al.; While unleaded gasoline has the advantage of eliminating lead from automobile exhaust, its potential to reduce the exhaust gas and particles, merits further examination . In the present studies, the concentrations of hydrocarbons (HC) and carbon mono-oxides (CO) in emissions were analyzed on Santana engine Dynamometer under a standard test cycle, and total exhaust particles were collected from engines using leaded and unleaded gasoline . It was found that unleaded gasoline reduced the emissions of CO and HC, and decreased the quantity of vehicle exhaust particulate matters by 60% . With the unleaded gasoline, only 23 kinds of organic substances, adsorbed in the particles, were identified by gas chromatography/mass spectrometer (GC/MS) while 32 components were detected using the leaded gasoline . The results of in vitro Salmonella/microsomal test and micronucleus induction assay in CHL cells indicated that both types of gasoline increased the number of histidine-independent colonies and the frequencies of micronucleus induction; no significant difference was found in their mutagenicity.

Mol Microbiol, 1999 Oct, 34(2), 295 - 304
FliK, the protein responsible for flagellar hook length control in Salmonella, is exported during hook assembly; Minamino T et al.; In wild-type Salmonella, the length of the flagellar hook, a structure consisting of subunits of the hook protein FlgE, is fairly tightly controlled at approximately 55 nm . Because fliK mutants produce abnormally elongated hook structures that lack the filament structure, FliK appears to be involved in both the termination of hook elongation and the initiation of filament formation . FliK, a soluble protein, is believed to function together with a membrane protein, FlhB, of the export apparatus to mediate the switching of export substrate specificity (from hook protein to flagellin) upon completion of hook assembly . We have examined the location of FliK during flagellar morphogenesis . FliK was found in the culture supernatants from the wild-type strain and from flgD (hook capping protein), flgE (hook protein) and flgK (hook-filament junction protein) mutants, but not in that from a flgB (rod protein) mutant . The amount of FliK in the culture supernatant from the flgE mutant was much higher than in that from the flgK mutant, indicating that FliK is most efficiently exported prior to the completion of hook assembly . Export was impaired by deletions within the N-terminal region of FliK, but not by C-terminal truncations . A decrease in the level of exported FliK resulted in elongated hook structures, sometimes with filaments attached . Our results suggest that the export of FliK during hook assembly is important for hook-length control and the switching of export substrate specificity.

J Rheumatol, 1999 Nov, 26(11), 2485 - 8
Detection of Salmonella infantis in synovial fluid cells of a patient with reactive arthritis; Ekman P et al.; We investigated a patient with Salmonella infantis triggered reactive arthritis (ReA) for a possible occurrence of S . infantis-specific antigens and DNA in the synovial fluid (SF) cells . S . infantis-specific antigens were abundantly observed by immunofluorescence in SF cells of the patient during acute joint inflammation . Salmonella-specific DNA was detected by Southern blotting of the amplified polymerase chain reaction product once, but the result could not be repeated . It seems that if bacterial DNA exists in inflamed joints in Salmonella triggered ReA, its amount is extremely low . This is the first report of intraarticular S . infantis antigens and potentially of Salmonella DNA in Salmonella triggered ReA.

Mol Biol Evol, 1999 Nov, 16(11), 1586 - 98
Sequence evolution in bacterial endosymbionts having extreme base compositions; Clark MA et al.; A major limitation on ability to reconstruct bacterial evolution is the lack of dated ancestors that might be used to evaluate and calibrate molecular clocks . Vertically transmitted symbionts that have cospeciated with animal hosts offer a firm basis for calibrating sequence evolution in bacteria, since fossils of the hosts can be used to date divergence events . Sequences for a functionally diverse set of genes have been obtained for bacterial endosymbionts (Buchnera) from two pairs of aphid host species, each pair diverging 50-70 MYA . Using these dates and estimated numbers of Buchnera generations per year, we calculated rates of base substitution for neutral and selected sites of protein-coding genes and overall rates for rRNA genes . Buchnera shows homogeneity among loci with regard to synonymous rate . The Buchnera synonymous rate is about twice that for low-codon-bias genes of Escherichia coli-Salmonella typhimurium on an absolute timescale, and fourfold higher on a generational timescale . Nonsynonymous substitutions show a greater rate disparity in favor of Buchnera, a result consistent with a genomewide decrease in selection efficiency in Buchnera . Ratios of synonymous to nonsynonymous substitutions differ for the two pairs of Buchnera, indicating that selection efficiency varies among lineages . Like numerous other intracellular bacteria, such as Rickettsia and Wolbachia, Buchnera has accumulated amino acids with codons rich in A or T . Phylogenetic reconstruction of amino acid replacements indicates that replacements yielding increased A + T predominated early in the evolution of Buchnera, with the trend slowing or stopping during the last 50 Myr . This suggests that base composition in Buchnera has approached a limit enforced by selective constraint acting on protein function.

Clin Diagn Lab Immunol, 1999 Nov, 6(6), 832 - 7
Antibiotics modulate vaccine-induced humoral immune response; Woo PC et al.; The effects of antibiotics on the antigen-specific humoral immune response are not known . Macrolides, tetracyclines, and beta-lactams are commonly prescribed antibiotics . The first two are known to have immunomodulatory activities . The effects of clarithromycin, doxycycline, and ampicillin on the primary and secondary antibody responses to tetanus toxoid, a pneumococcal polysaccharide vaccine, a hepatitis B virus surface antigen (HBsAg) vaccine, and live attenuated Salmonella typhi (Ty21a) were investigated using a mouse model . For the mice receiving the tetanus toxoid, the immunoglobulin M (IgM) level of the clarithromycin group at day 7 was significantly lower than the corresponding antibody level of the normal saline (NS) group . For the mice receiving the pneumococcal polysaccharide vaccine, the total antibody and IgM levels of the clarithromycin group and the IgM level of the doxycycline group at day 7 were significantly lower than the corresponding antibody levels of the ampicillin and NS groups . For the mice receiving the HBsAg vaccine, the IgM level of the doxycycline group at day 7 was significantly lower than the corresponding antibody levels of the clarithromycin and NS groups, while the IgM level of the clarithromycin group at day 28 was significantly lower than the corresponding antibody levels of the doxycycline, ampicillin, and NS groups . For the mice receiving all three vaccines, there were no statistically significant differences between any of the antibody levels of the ampicillin group and the corresponding antibody levels of the NS group . For the mice receiving Ty21a, the total antibody levels of the ampicillin group at days 7 and 21 were significantly higher than the corresponding antibody levels of the NS group . Moreover, the IgM levels of the clarithromycin, doxycycline, and ampicillin groups at days 7 and 21 were significantly higher than the corresponding antibody levels of the NS group . Furthermore, the total antibody level of the ampicillin group at day 21 was significantly higher than the corresponding antibody level of the doxycycline group . For all four vaccines, there were no statistically significant differences among the serum levels of interleukin-10 and gamma interferon for the mice treated with the various antibiotics . We conclude that clarithromycin and doxycycline, but not ampicillin, suppress the antibody responses of mice to T-cell-dependent and T-cell-independent antigens, whereas all three antibiotics enhance the antibody response to live attenuated mucosal bacterial vaccines.

N Engl J Med, 1999 Nov 4, 341(19), 1420 - 5
An outbreak of multidrug-resistant, quinolone-resistant Salmonella enterica serotype typhimurium DT104; Molbak K et al.; BACKGROUND: Food-borne salmonella infections have become a major problem in industrialized countries . The strain of Salmonella enterica serotype typhimurium known as definitive phage type 104 (DT104) is usually resistant to five drugs: ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline . An increasing proportion of DT104 isolates also have reduced susceptibility to fluoroquinolones . METHODS: The Danish salmonella surveillance program determines the phage types of all typhimurium strains from the food chain, and in the case of suspected outbreaks, five-drug-resistant strains are characterized by molecular methods . All patients infected with five-drug-resistant typhimurium are interviewed to obtain clinical and epidemiologic data . In 1998, an outbreak of salmonella occurred, in which the strain of typhimurium DT104 was new to Denmark . We investigated this outbreak and report here our findings . RESULTS: Until 1997, DT104 infections made up less than 1 percent of all human salmonella infections . The strain isolated from patients in the first community outbreak of DT104 in Denmark, in 1998 was resistant to nalidixic acid and had reduced susceptibility to fluoroquinolones . The outbreak included 25 culture-confirmed cases . Eleven patients were hospitalized, and two died . The molecular epidemiology and data from patients indicated that the primary source was a Danish swine herd . Furthermore, the investigation suggested reduced clinical effectiveness of treatment with fluoroquinolones . CONCLUSIONS: Our investigation of an outbreak of DT104 documented the spread of quinolone-resistant bacteria from food animals to humans; this spread was associated with infections that were difficult to treat . Because of the increase in quinolone resistance in salmonella, the use of fluoroquinolones in food animals should be restricted.

Clin Lab Med, 1999 Sep, 19(3), 469 - 87, v
Salmonella and Shigella species; Edwards BH; Salmonella and Shigella are the second and third most common causes of bacterial food-borne disease in the United States and are a major global health problem . The prevention and treatment of disease caused by these organisms are complicated by the increase in multidrug-resistant strains and the lack of an effective vaccine . This article discusses the epidemiology, clinical features, and diagnostic techniques for both enteric pathogens.

Am J Trop Med Hyg, 1999 Oct, 61(4), 654 - 7
Rapid serologic diagnosis of pediatric typhoid fever in an endemic area: a prospective comparative evaluation of two dot-enzyme immunoassays and the Widal test; Bhutta ZA et al.; We evaluated the diagnostic sensitivity and specificity of two dot-enzyme-linked immunoassays (Typhidot and Typhidot-M; Malaysian Biodiagnostic Research SDN BHD, Kuala Lumpur, Malaysia), assessing IgG and IgM antibodies against the outer membrane protein (OMP) of Salmonella typhi, and the Widal test in comparison with blood culture in a consecutive group of children with suspected typhoid fever . Of 97 children with suspected typhoid fever, the disease was confirmed bacteriologically in 46 (47%), whereas 25 (26%) were considered to have typhoid fever on clinical grounds . An alternative diagnosis was made in 26 (27%) . The Typhidot and Typhidot-M were superior to the Widal test in their diagnostic sensitivity and specificity, although values (sensitivity = 85-94% and specificity = 77-89%) were significantly lower than in other regional reports . The lower specificity of the Typhidot in our series may represent regional differences in the genomic structure and plasticity of the OMP of S . typhi and merits further evaluation of these tests in diverse geographic locations.

Eur Rev Med Pharmacol Sci, 1998 May-Aug, 2(3-4), 131 - 6
Comparison of two non-absorbable antibiotics for treatment of bacterial enteritis in children; Beseghi U et al.; Thirty-one children with bacterial diarrhoea were administered an oral suspension of rifaximin (14 children, mean age: 4.3 yrs; dosage: 5 ml, equal to 100 mg, x 4/day for 3 days on average) or of neomycin + bacitracin (17 children, mean age: 3.6 yrs; dosage: 5 ml x 4/ day for 4 days on average) . Etiologic agents were: minor Salmonella spp in 9 and 7 cases respectively; enteropathogenic E . coli in 5 and 10 cases . Rifaximin yielded bacteriological cure in 12/14 children; the reference drug in 13/17 . With both antibiotics, stool number/day fell, after one day, from 6 on average, to normality (2-3 stools); within two days stool consistency and characteristics shifted to normal . Symptomatology was quickly eliminated in all of the cured children . Both treatments showed excellent systemic tolerability; rifaximin was completely tolerated also locally, while two cases of stomach ache were reported with the reference drug.

Appl Environ Microbiol, 1999 Nov, 65(11), 4830 - 6
Potential of three-Way randomly amplified polymorphic DNA analysis as a typing method for twelve Salmonella serotypes; Soto SM et al.; The potential of a three-way randomly amplified polymorphic DNA (RAPD) procedure (RAPD typing) for typing Salmonella enterica strains assigned to 12 serotypes was analyzed . The series of organisms used included 235 strains (326 isolates) collected mainly from clinical samples in the Principality of Asturias and 9 reference strains . RAPD typing was performed directly with broth cultures of bacteria by using three selected primers and optimized PCR conditions . The profiles obtained with the three primers were used to define RAPD types and to evaluate the procedure as a typing method at the species and serotype levels . The typeability was 100%; the reproducibility and in vitro stability could be considered good . The concordance of RAPD typing methods with serotyping methods was 100%, but some profiles obtained with two of the three primers were obtained with strains assigned to different serotypes . The discrimination index (DI) within the series of organisms was 0.94, and the DI within serotypes Typhimurium, Enteritidis, and Virchow were 0.72, 0.52, and 0.66, respectively . Within these serotypes the most common RAPD types were differentiated into phage types and vice versa; combining the types identified by the two procedures (RAPD typing and phage typing) resulted in further discrimination (DI, 0 . 96, 0.74, and 0.87, respectively) . The efficiency, rapidity, and flexibility of the RAPD typing method support the conclusion that it can be used as a tool for identifying Salmonella organisms and as a typing method that is complementary to serotyping and phage typing methods.

J Bacteriol, 1999 Nov, 181(21), 6650 - 5
Activation of the cryptic aac(6')-Iy aminoglycoside resistance gene of Salmonella by a chromosomal deletion generating a transcriptional fusion; Magnet S et al.; Salmonella enterica subsp . enterica serotype Enteritidis BM4361 and BM4362 were isolated from the same patient . BM4361 was susceptible to aminoglycosides, whereas BM4362 was resistant to tobramycin owing to synthesis of a 6'-N-acetyltransferase type I {AAC(6')-I} . Comparative analysis of nucleotide sequences, pulsed-field gel electrophoresis patterns, and Southern hybridizations indicated that the chromosomal aac(6')-Iy genes for the enzyme in both strains were identical and that BM4362 derived from BM4361 following a ca . 60-kb deletion that occurred 1.5 kb upstream from the resistance gene . Northern hybridizations showed that aac(6')-Iy was silent in BM4361 and highly expressed in BM4362 due to a transcriptional fusion . Primer extension mapping identified the transcriptional start site for aac(6')-Iy in BM4362: 5 bp downstream from the promoter of the nmpC gene . Study of the distribution of aac(6')-Iy by PCR and Southern hybridization with a specific probe indicated that the gene, although not found in S . enterica subsp . arizonae, was specific for Salmonella . In this bacterial genus, aac(6')-Iy was located downstream from a cluster of seven open reading frames analogous to an Escherichia coli locus that encodes enzymes putatively involved in carbohydrate transport or metabolism . This genomic environment suggests a role in the catabolism of a specific sugar for AAC(6')-Iy in Salmonella.

J Mol Biol, 1999 Oct 29, 293(3), 693 - 701
Mutations improving the folding of phage P22 tailspike protein affect its receptor binding activity; Baxa U et al.; Four previously isolated mutations in Salmonella phage P22 tailspike protein were used to study the relationship between protein stability, folding, and function . Tailspike protein binds and hydrolyzes the repetitive O-antigen structure in Salmonella lipopolysaccharide . Four mutations (V331G, V331A, A334V, A334I) are known to increase the folding efficiency, and two of them (at position 331) also increase the thermal stability of the protein . Octasaccharides comprising two repeating units of the O-antigens from two different Salmonella strains were employed to analyze the receptor binding function of the mutant proteins . Their endorhamnosidase enzymatic activity was assayed with the aid of a fluorescence-labeled dodecasaccharide . Both V331A and V331G were found to strongly affect O-antigen binding . Octasaccharide binding affinities of the mutant proteins are reduced tenfold and 200-fold, corresponding to a loss of 17% and 36% of the standard free energy of binding, respectively . Both mutations at position 334 affected O-antigen binding only slightly (DeltaDeltaG(0)B approximately 1 kJ/mol), but these mutations reduce the thermal stability of the protein . The observed effects on the endoglycosidase activity are fully explained by the changes in substrate binding, suggesting that neither of the mutations affect the catalytic rate . Crystal structures of all four mutants were determined to a resolution of 2.0 A . Except for the partly or completely missing side-chain, no significant changes compared to the wild-type protein structure were found for the mutants at position 331, whereas a small but significant backbone displacement around the mutation site in A334V and A334I may explain the observed thermal destabilization .

Vet Microbiol, 1999 Sep 29, 69(4), 265 - 75
Colonisation of the chicken caecum by afimbriate and aflagellate derivatives of Salmonella enterica serotype Enteritidis; Allen-Vercoe E et al.; A semi-quantitative cloacal-swab method was used as an indirect measure of caecal colonisation of one-day old and five-day old chicks after oral dosing with wild-type Salmonella enterica serovar Enteritidis PT4 and genetically defined isogenic derivatives lacking the ability to elaborate flagella or fimbriae . Birds of both ages were readily and persistently colonised by all strains although there was a decline in shedding by the older birds after about 21 days . There were no significant differences in shedding of wild-type or mutants in single-dose experiments . In competition experiments, in which five-day old birds were dosed orally with wild-type and mutants together, shedding of non-motile derivatives was significantly lower than wild-type . At 35 days post infection, birds were sacrificed and direct counts of mutants and wild-type from each caecum were determined . Whilst there appeared to be poor correlation between direct counts and the indirect swab method, the overall trends shown by these methods of assessment indicated that flagella and not fimbriae were important in caecal colonisation in these models.

J Med Microbiol, 1999 Nov, 48(11), 1037 - 42
Analysis of Salmonella enterica serotype Typhimurium by phage typing, antimicrobial susceptibility and pulsed-field gel electrophoresis; Kariuki S et al.; Three typing methods commonly used for bacteria--phage typing, antimicrobial susceptibility and pulsed-field gel electrophoresis (PFGE)- were used to characterise 64 Salmonella enterica serotype Typhimurium isolates from individual adult patients from Nairobi, Kenya . The isolates encompassed 11 definitive phage types (DTs), which fell into eight PFGE clusters; 31.3% of isolates were either untypable or reacted nonspecifically with the phages used for typing and 26.6% were of DT 56 . Plasmids of c . 100 kb were responsible for self-transferable multiresistance among the isolates . Analysis by PFGE and phage type demonstrated that multiresistant Typhimurium strains causing diarrhoea and invasive disease were multiclonal.

Gastroenterol Hepatol, 1999 Aug-Sep, 22(7), 342 - 4
{Multidrug-resistant Salmonella a significant clinical problem?}; Sicilia B et al.; The incidence of infections caused by Salmonella strains resistant to antibiotics, including ampicillin, chloramphenicol, streptomycin, sulfonamides, tetracycline and even amoxicyllin-clavulanate, is increasing . We present two cases that illustrate the potential severity of infections caused by multidrug-resistant Salmonella and also the difficulty of reaching a differential diagnosis with inflammatory bowel disease.

Eur J Clin Microbiol Infect Dis, 1999 Sep, 18(9), 609 - 20
Experience with Salmonella typhi Vi capsular polysaccharide vaccine; Hessel L et al.; Typhoid fever remains an important health threat in many parts of the world, with an estimated 16 million cases and 600,000 deaths occurring each year . The emergence of Salmonella typhi strains multiply resistant to antibiotics has complicated the treatment of this disease . Field experience of 8 years shows that a vaccine composed of purified Vi capsular polysaccharide of Salmonella typhi, given as a single intramuscular or deep subcutaneous injection, has consistent immunogenicity and efficacy . Side effects, based on reports since 1989, are infrequent and mild . Furthermore, the Vi vaccine may be administered simultaneously with other common "travel" vaccines, at two different sites of injection, without affecting immunogenicity and tolerability . This review presents an update of the development and clinical experience with the Salmonella typhi Vi polysaccharide vaccine (Typhim Vi; Pasteur Merieux Connaught, France).

Infect Immun, 1999 Nov, 67(11), 5806 - 10
Safety and immunogenicity of Vi conjugate vaccines for typhoid fever in adults, teenagers, and 2- to 4-year-old children in Vietnam; Kossaczka Z et al.; The capsular polysaccharide of Salmonella typhi, Vi, is an essential virulence factor and a protective vaccine for people older than 5 years . The safety and immunogenicity of two investigational Vi conjugate vaccines were evaluated in adults, 5- to 14-year-old children, and 2- to 4-year-old children in Vietnam . The conjugates were prepared with Pseudomonas aeruginosa recombinant exoprotein A (rEPA) as the carrier, using either N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP; Vi-rEPA(1)) or adipic acid dihydrazide (ADH; Vi-rEPA(2)) as linkers . None of the recipients experienced a temperature of >38.5 degrees C or significant local reactions . One injection of Vi-rEPA(2) into adults elicited a geometric mean (GM) increase in anti-Vi immunoglobulin G (IgG) from 9.62 enzyme-linked immunosorbent assay units/ml (EU) to 465 EU at 6 weeks; this level fell to 119 EU after 26 weeks . In the 5- to 14-year-old children, anti-Vi IgG levels at 6 weeks elicited by Vi-rEPA(2), Vi-rEPA(1), and Vi were 169, 22.8, and 18.9 EU, respectively (P = 0.0001 for Vi-rEPA(1) and Vi with respect to Vi-rEPA(2)) . At 26 weeks, the anti-Vi IgG levels for recipients of Vi-rEPA(2), Vi-rEPA(1), and Vi were 30.0, 10.8, and 13.4 EU, respectively (P < 0.001 for Vi-rEPA(1) and Vi with respect to Vi-rEPA(2)); all were higher than the preinjection levels (P = 0 . 0001) . Vi-rEPA(2) also elicited the highest anti-Vi IgM and IgA levels of the three vaccines . In the 2- to 4-year-old children at 6 weeks following the first injection, Vi-rEPA(2) elicited an anti-Vi IgG level of 69.9 EU compared to 28.9 EU for Vi-rEPA(1) (P = 0.0001) . Reinjection increased Vi antibody levels from 69.9 to 95.4 EU for Vi-rEPA(2) and from 28.9 to 83.0 EU for Vi-rEPA(1) . At 26 weeks, anti-Vi IgG levels remained higher than those at preinjection (30.6 versus 0.18 for Vi-rEPA(2) and 12.8 versus 0.33 for Vi-rEPA(1); P = 0.0001 for both) . Vi vaccine is recommended for individuals of 5 years of age or older . In the present study, the GM level of anti-Vi IgG elicited by two injections of Vi-rEPA(2) in the 2- to 4-year-old children was higher than that elicited by Vi in the 5- to 14-year-old children (30.6 versus 13.4; P = 0.0001) . The safety and immunogenicity of the Vi-rEPA(2) conjugate warrant further investigation.

Infect Immun, 1999 Nov, 67(11), 5651 - 7
Analysis of virulence of clinical isolates of Salmonella enteritidis in vivo and in vitro; Lu S et al.; Salmonella enterica serotype Enteritidis (S . enteritidis) is a major food-borne pathogen, and its incidence among all Salmonella serotypes has increased dramatically in the last two decades . To study the virulence characteristics of clinical isolates of S . enteritidis, we determined the 50% lethal doses (LD(50)) in mice of isolates of two major phage types (4 and 8) . Isolates of both phage types showed a wide range of LD(50) after oral inoculation, varying from under 10(2) organisms to over 10(8) organisms . No significant difference in LD(50) was observed between the phage types . These observations indicated that clinical isolates of S . enteritidis are highly heterogeneous in their ability to cause death in mice . We compared the LD(50)s of these isolates to the results observed from in vitro pathogenicity assays . We also analyzed these isolates for recognized Salmonella virulence loci (spv, sodCI, sopE, and sef) . The in vitro phenotypes of the isolates showed no obvious correlation with their LD(50) in any given assay, and the virulence genes tested were present in all isolates . However, the isolate with the lowest LD(50) (isolate 97A 2472) was resistant to acidified sodium nitrite (ASN) . Moreover, the most acid-susceptible, macrophage-susceptible, and ASN-susceptible isolates were attenuated for virulence in mice . These results, based on extensive analysis of clinical isolates of S . enteritidis, demonstrate the complex nature of Salmonella pathogenesis in mice . Our results also indicate the limitation of in vitro assays in predicting in vivo virulence.

Life Sci, 1999, 65(14), 1463 - 75
Platelet activation and modulation of the induction of nitric oxide synthase in the conscious rat; Picunio S et al.; Injection of lipopolysaccharide (LPS) (Salmonella W . Typhosa i.v . bolus) into conscious rats, induced a rapid drop of circulating platelets analogous to that induced by ADP . The animals showed a small fall in mean arterial blood pressure (MABP), an increase in heart rate and a significant increase in plasma nitrite and nitrate level . This result is consistent with the stimulation of an inducible NO synthase (i-NOS) . The administration of the stable prostacyclin analogue, iloprost plus ADP or LPS, significantly protected against the decrease in free platelet number induced by ADP or LPS . The plasma nitrite and nitrate level stimulated by LPS was significantly reduced by iloprost and also by prostacyclin . These results are consistent with an inhibition of i-NOS by agents that increase the intracellular level of cAMP . The administration of the NO donor S-Nitroso-N-acyl-D-penicillamine (SNAP) plus ADP or LPS, significantly prevented thrombocytopenia induced by ADP and by LPS . SNAP did not decrease the plasma nitrite and nitrate level stimulated by LPS; furthermore it induced a significant increase of heart rate, without affecting MABP, suggesting a direct accelerating effect of NO on the sino-atrial node . The administration of S-nitroso-glutathione (GSNO), a stable nitrosothiol, plus ADP or LPS, significantly prevented thrombocytopenia induced by ADP but not by LPS . GSNO significantly reduced the plasma nitrite and nitrate level stimulated by LPS . These data demonstrate that the L-Arginine: NO pathway in vivo may be modulated by prostanoids and that compounds which increase cAMP, such as iloprost, are able to protect against LPS-induced early thrombocytopenia.

Pediatr Infect Dis J, 1999 Oct, 18(10 Suppl), S56 - 61
Etiology of pneumonia, sepsis and meningitis in infants younger than three months of age in Ethiopia; Muhe L et al.; METHODS: Within a multicenter study coordinated by WHO, an investigation of the etiologic agents of pneumonia, sepsis and meningitis was performed among infants younger than 3 months of age seen at the Ethio-Swedish Children's Hospital in Addis Ababa for a period of 2 years . Of the 816 infants enrolled 405 had clinical indications for investigation . RESULTS: There were a total of 41 isolates from blood cultures from 40 infants . The study showed that the traditionally known acute respiratory infection pathogen Streptococcus pneumoniae was most common in this extended neonatal age group, found in 10 of 41 blood isolates . Streptococcus pyogenes was a common pathogen in this setting (9 of 41 blood isolates), whereas Salmonella group B was found in 5 of 41 isolates . Streptococcus agalactiae, which is a common pathogen in developed countries, was absent . A study of the susceptibility pattern of these organisms suggests that a combination of ampicillin with an aminoglycoside is adequate for initial treatment of these serious bacterial infections, but the combination is not optimal for the treatment of Salmonella infections . Among 202 infants on whom immunofluorescent antibody studies for viruses were performed based on nasopharyngeal aspirates, respiratory syncytial virus was found in 57 (28%) infants, and Chlamydia trachomatis was isolated in 32 (15.8%) of 203 infants.

Mod Pathol, 1999 Oct, 12(10), 949 - 55
Histopathology of typhoid enteritis: morphologic and immunophenotypic findings; Kraus MD et al.; Enteric fever is a systemic illness caused by Salmonella infection, with S . typhi, S . paratyphi, and S . enteritidis being the most common serotypes . Humans are the only reservoir for S . typhi, and its predilection for the ileum is due to the fact that organisms enter the body by translocation across specialized Peyer's patch epithelium and then proliferate in the mucosal macrophages . The lesions in bowel and mesenteric lymph nodes are distinctive and mimic Kikuchi-Fujimoto disease and Rosai-Dorfman disease as well as infections caused by some non-salmonella bacteria . The four cases presented in this report, two culture-confirmed, all exhibited ileal mucosal hypertrophy caused by a neutrophil-poor monocyte/macrophage-rich hyperplasia . Though diffuse areas were present, much of the lesional proliferation was nodular, representing macrophage infiltration and colonization by the monocytes and macrophages . Immunophenotypic studies, which showed a CD68+, lysozyme+, UCHL-1+, OPD4-, CD4-, s100- profile, were helpful in distinguishing these lesions from other processes, including Kikuchi-Fujimoto disease and Rosai-Dorfman disease . Although rare in developed countries, enteric fever should be considered in any patient with recent travel to endemic areas and in the context of illness thought to be related to contaminated foods.

Clin Infect Dis, 1999 Sep, 29(3), 673 - 7
Muscle infections caused by Salmonella species: case report and review; Collazos J et al.; We describe a patient with salmonella pyomyositis and review 30 other cases reported during the past 4 decades . Men outnumbered women by 2.9 to 1, and the median age of the patients was 51 years . Approximately one-half the cases were caused by Salmonella enteritidis . Infected vascular aneurysms were observed in seven patients . Prior salmonella infections and local trauma or lesions were common . Diverse underlying conditions, mainly diabetes and human immunodeficiency virus infection, were present in 81% of the patients, and the psoas muscle was involved in 55% of the cases . One-third of the patients died, and relapses were common after a median time of 5 weeks (range, 4.5-27 weeks) in those who survived . Most patients had anemia, and pathogens were recovered from blood samples from two-thirds of the patients . Salmonella should be considered as a causative agent of muscle infections in the appropriate clinical setting, particularly in patients with underlying diseases or preexisting vascular aneurysms.

Lett Appl Microbiol, 1999 Sep, 29(3), 156 - 9
Molecular fingerprinting of Salmonella serotype Glostrup; Old DC et al.; Thirteen isolates of Salmonella serotype Glostrup (antigenic formula, 6.8:z10:e,n,z15) from various sources and countries were analysed by ribotyping and IS200 fingerprinting . Both methods provided a high index of strain discrimination by allowing detection of three ribotypes and eight IS200 fingerprints which, though generally related, were readily distinguishable . The findings of this analysis confirm the usefulness of ribotyping and IS200 fingerprinting for studying the epidemiology of rarely isolated salmonellae of serogroup C.

Toxicol Pathol, 1999 Sep-Oct, 27(5), 501 - 6
Oxymetholone: I . Evaluation in a comprehensive battery of genetic toxicology and in vitro transformation assays; Holden HE et al.; Oxymetholone is generally assumed to be a nongenotoxic carcinogen . This assumption is based primarily on the results of an Ames test, existing data in repeat-dose toxicology studies, and the predicted results of a 2-yr National Toxicology Program (NTP) rat carcinogenicity bioassay . To provide a comprehensive assessment of its genotoxicity in a standard battery of mutagenicity assays, oxymetholone was tested in microbial and mammalian cell gene mutation assays, in an in vitro cytogenetics assay (human lymphocytes), and in an in vivo micronucleus assay . Oxymetholone was also tested in an in vitro morphologic transformation model using Syrian hamster embryo (SHE) cells . These studies were initiated and completed prior to the disclosure of the results of the NTP bioassay . Oxymetholone was tested at doses up to 5,000 microg/plate in the bacterial plate incorporation assay using 4 Salmonella strains and the WP2 uvrA (pKM101) strain of Escherichia coil . There was no induction of revertants up to the highest dose levels, which were insoluble as well as toxic . In the L5178Y tk+/- mouse lymphoma assay, doses up to 30 microg/ml reduced relative survival to approximately 30% with no increase in mutants . Male or female human lymphocytes were exposed in vitro to oxymetholone for 24 hr without S9 or 3 hr with S9 and evaluated for the induction of chromosomal aberrations . There was no increase in aberration frequency over control levels and no difference between male and female cells . Peripheral blood from Tg.AC transgenic mice treated dermally for 20 wk with 0, 1.2, 6.0, or 12.0 mg/day of oxymetholone and from p53 transgenic mice treated orally by gavage for 26 wk with 125, 625, or 1,250 mg/kg/day of oxymetholone was evaluated for micronuclei in polychromatic and normochromatic erythrocytes . There was no difference in micronuclei frequency between control and treated animals . These results confirm that oxymetholone is not genotoxic in a comprehensive battery of mutagenicity assays . In the SHE assay, oxymetholone produced a significant increase in morphologically transformed colonies at dose levels of 13-18 microg/ml . The lack of genotoxicity of oxymetholone, the positive response in the in vitro transformation assay, and the results of transgenic mouse carcinogenicity assays will provide an interesting perspective on the results of an on-going NTP rat carcinogenicity bioassay.

J Immunol, 1999 Nov 1, 163(9), 4924 - 30
Distinct mechanisms target stress and extracellular signal-activated kinase 1 and Jun N-terminal kinase during infection of macrophages with Salmonella; Procyk KJ et al.; The interaction between bacteria and macrophages is central to the outcome of Salmonella infections . Salmonella can escape killing by these phagocytes and survive and multiply within them, giving rise to chronic infections . Cytokines produced by infected macrophages are involved in the early gastrointestinal pathology of the infection as well as in the induction and maintenance of the immune response against the invaders . Jun N-terminal kinases (JNK) are activated by inflammatory stimuli and play a role in cytokine production . We have investigated the signaling routes leading to JNK activation in Salmonella-infected macrophages and have discovered that they differ radically from the mechanisms operating in epithelial cells . In particular, activation of the JNK kinase stress and extracellular-activated kinase 1 (SEK1) and of JNK in macrophages occurs independently of actin rearrangements and of the GTPases Cdc42 and Rac, essential mediators in other cells . Activation of JNK is effected by a novel pathway comprising tyrosine kinase(s), phosphoinositide 3-kinase and, likely, atypical protein kinase C zeta . SEK1 is stimulated by a distinct mechanism involving phosphatidylcholine-phospholipase C and acidic sphingomyelinase . Dominant-negative SEK1 can block JNK activation by LPS, but not by Salmonella . These data demonstrate that SEK1 and JNK are activated independently in Salmonella-infected macrophages and offer experimental support for the concept that incoming signals can direct the selective coupling of downstream pathways to elicit highly specific responses . Inhibitors of stress kinase pathways are receiving increasing attention as potential anti-inflammatory drugs . The precise reconstruction of stimulus-specific pathways will be instrumental in predicting/evaluating the effects of the inhibitors on a given pathological condition.

Can J Microbiol, 1999 Sep, 45(9), 723 - 31
Salmonella landau as a live vaccine against Escherichia coli O157:H7 investigated in a mouse model of intestinal colonization; Conlan JW et al.; The present study was performed to assess the potential of a humoral mucosal immune response directed against the O157 antigen of Escherichia coli O157:H7 to prevent intestinal colonization by the pathogen . To this end, mice were gavaged with inocula of Salmonella landau, a Salmonella strain that naturally expresses the O157 antigen . Salmonella landau was avirulent for mice . Despite this, mice exposed to S . landau developed high titres of serum and coproantibodies against the O157 antigen . These mice, compared with controls, demonstrated some ability to resist transient intestinal colonization by an oral inoculum of an isolate of E . coli O157:H7 . These findings suggest that a local immune response directed against the O157 antigen might increase host resistance to this pathogen.

Clin Infect Dis, 1999 Nov, 29(5), 1151 - 6
Clinical and prognostic categorization of extraintestinal nontyphoidal Salmonella infections in infants and children; Sirinavin S et al.; The study included 172 patients, aged 0-15 years, for whom at least 1 nonfecal, nonurinary specimen was culture-positive for nontyphoidal Salmonella . Ninety-five percent had positive blood cultures . Immunocompromising diseases were found in 19% of 74 infants and 77% of 98 children . Associations between the study factors and outcomes, as localized infection or death, were assessed by logistic regression analysis . Thirty-three patients had localized infections . An adjusted risk factor for development of localized infections was an age of <12 months (P=.003) . There were 17 deaths . The case-fatality rates were 43% and 10% for immunocompromised and 5% and 0% for nonimmunocompromised infants and children, respectively . Adjusted risk factors for death were age of <12 months (P=.006), inappropriate antimicrobial therapy (P=.014), meningitis or culture-proven pneumonia due to nontyphoidal Salmonella (P=.004), and immunocompromised status (P<.001) . The clinical courses and prognoses for infants and children with extraintestinal infection due to nontyphoidal Salmonella can be categorized into 4 groups according to the characteristics of age (infants vs . children) and host status (immunocompromised vs . nonimmunocompromised).

Arthritis Rheum, 1999 Oct, 42(10), 2045 - 54
Modulation of peripheral blood mononuclear cell activation status during Salmonella-triggered reactive arthritis; Kirveskari J et al.; OBJECTIVE: To determine the activation status of mononuclear cells in the peripheral circulation during the acute phase and the recovery phase of Salmonella-triggered reactive arthritis (ReA) . METHODS: Peripheral blood mononuclear cells (PBMC) were obtained from 8 patients with Salmonella infection (4 with ReA and 4 without) and were studied by reverse transcription-polymerase chain reaction for messenger RNA (mRNA) of proinflammatory and antiinflammatory cytokines, by flow cytometry (FC) for cell surface activation and adhesion molecules, by immunofluorescence (IF) microscopy for bacterial antigens, and by FC, IF, and DNA fragmentation on gel for signs of apoptosis . RESULTS: During the acute phase of the infection, PBMC were activated in all patients, as characterized by high levels of expression of CD14, CD11b, and CD11c on monocytes . In the patients with ReA, PBMC also had the capacity to produce interleukin-1beta (IL-1beta), IL-6, IL-8, IL-10, and tumor necrosis factor alpha . During the amelioration of disease, monocyte activation was decreased in all patients . A complete down-regulation of CD14 was detected only in the patients with ReA, whereas the expression of CD14 in the patients without ReA was positive and was similar to that in healthy controls . In addition, cytokine mRNA levels decreased regardless of the presence of Salmonella antigens in blood cells in all 4 patients with ReA . CONCLUSION: High levels of expression of some activation and adhesion molecules and elevated levels of mRNA for certain cytokines that are predominantly produced by monocytes were found in PBMC from patients with acute Salmonella-triggered ReA, which suggests that these cells are activated . On the other hand, complete down-regulation of CD14 and a marked decrease in the cytokine production capacity during amelioration of the disease suggest that suppression of PBMC activity might be involved in recovery from ReA.

J Clin Microbiol, 1999 Nov, 37(11), 3572 - 7
Detection of decreased fluoroquinolone susceptibility in Salmonellas and validation of nalidixic acid screening test; Hakanen A et al.; We evaluated 1,010 Salmonella isolates classified as fluoroquinolone susceptible according to the National Committee for Clinical Laboratory Standards guidelines for susceptibility to nalidixic acid and three fluoroquinolones . These isolates were divided into two distinct subpopulations, with the great majority (n = 960) being fully ciprofloxacin susceptible and a minority (n = 50) exhibiting reduced ciprofloxacin susceptibility (MICs ranging between 0.125 and 0.5 microg/ml) . The less ciprofloxacin-susceptible isolates were uniformly resistant to nalidixic acid, while only 12 (1.3%) of the fully susceptible isolates were nalidixic acid resistant . A similar association was observed between resistance to nalidixic acid and decreased susceptibility to ofloxacin or norfloxacin . A mutation of the gyrA gene could be demonstrated in all isolates for which the ciprofloxacin MICs were >/= 0.125 microg/ml and in 94% of the nalidixic acid-resistant isolates but in none of the nalidixic acid-susceptible isolates analyzed . Identification of nalidixic acid resistance by the disk diffusion method provided a sensitivity of 100% and a specificity of 87.3% as tools to screen for isolates for which the MICs of ciprofloxacin were >/= 0.125 microg/ml . We regard it as important that microbiology laboratories endeavor to recognize these less susceptible Salmonella strains, in order to reveal their clinical importance and to survey their epidemic spread.

Mutat Res, 1999 Sep 15, 445(1), 81 - 91
SOS induction of selected naturally occurring substances in Escherichia coli (SOS chromotest); Kevekordes S et al.; Naturally occurring substances were tested for genotoxicity using a modified laboratory protocol of the Escherichia coli PQ37 genotoxicity assay (SOS chromotest) in the presence and in the absence of an exogenous metabolizing system from rat liver S9-mix . Aristolochic acid I, II, the plant extract aristolochic acid and psoralene were genotoxic; cycasine, emodine, monocrotaline and retrorsine were classified as marginal genotoxic in the SOS chromotest in the absence of S9-mix . In the presence of an exogenous metabolizing system from rat liver S9-mix aristolochic acid I, the plant extract, beta-asarone, cycasin, monocrotaline, psoralen and retrorsine showed genotoxic effects; aristolochic acid II marginal genotoxic effects . Arecoline, benzyl acetate, coumarin, isatidine dihydrate, reserpine, safrole, sanguinarine chloride, senecionine, senkirkine, tannin and thiourea revealed no genotoxicity in the SOS chromotest either in the presence or in the absence of an exogenous metabolizing system from rat liver S9-mix . For 17 of 20 compounds, the results obtained in the SOS chromotest could be compared to those obtained in the Ames test . It was found that 12 (70.6%) of these compounds give similar responses in both tests (6 positive and 6 negative responses) . The present investigation and those reported earlier, the SOS chromotest, using E . coli PQ37, was able to detect correctly most of the Salmonella mutagens and non-mutagens.

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