Salmonella

Arch Soc Esp Oftalmol, 2000 Jun, 75(6), 377 - 82
{Effect of topical pranoprofen on the lipoxygenase metabolism of the arachidonic and in endotoxin-induced uveitis}; Torron C et al.; PURPOSE: To study the antiinflammatory effect of topical pranoprofen on the lipoxygenase metabolism of the arachidonic acid in albino rabbits . METHODS: Endotoxin-induced uveitis (EIU) was produced in albino rabbits by intravitreal injection in the right eye with 10 microg of Salmonella typhymurium lipopolysacharide A in 5 microl saline solution . We have used 5 groups of 12 animals each . Control group (G-I) was injected with 5 microl of saline solution and 5 microl of ET solution were injected in the remaining groups . Groups III, IV and V were treated with topical pranoprofen 2 hours before intravitreal injection, immediately after and every 6, 4 and 2 hours respectively . The animals were sacrificed 24 hours after the ET administration . Cellular and B4 leukotrien concentration in the aqueous humour was determined . RESULTS: The groups treated with pranoprofen showed a significant decrease in the cellular concentration in relation to the group of endotoxin (G-II) . We did not observe any difference in the B4 leukotriene concentration between ET group and topical pranoprofen groups . CONCLUSION: Topical pranoprofen has not increased the lipoxygenase metabolism of the arachidonic acid.

Am J Nephrol, 2000 Nov-Dec, 20(6), 468 - 72
Cytomegalovirus colitis during mycophenolate mofetil therapy for Wegener's granulomatosis; Woywodt A et al.; Cytomegalovirus (CMV) infection of the gastrointestinal tract is an increasingly recognized cause of morbidity and mortality during the course of HIV infection and in association with immunosuppressive pharmacotherapy . Mycophenolate mofetil, a novel immunosuppressive drug, is currently used in renal transplant recipients and is under evaluation for a variety of disorders . There is preliminary evidence to suggest that CMV reactivation may be more common during treatment with mycophenolate than with other immunosuppressive drugs . We present the case of a 59-year-old male with Wegener's granulomatosis who received mycophenolate and presented with guaiac-positive diarrhea 8 weeks after recovery from Salmonella brandenburg infection . CMV serology and assays for CMV antigens were entirely negative . Colonoscopy demonstrated pancolitis and examination of the specimens disclosed CMV infection . Ganciclovir was administered and the patient made an uneventful recovery . We discuss aspects of gastrointestinal CMV infection with an emphasis on pitfalls in diagnosis and the association with mycophenolate mofetil treatment . We also speculate as to the potential role of previous Salmonella infection and proinflammatory cytokines in CMV reactivation . In summary, when using mycophenolate, clinicians should be more aware of CMV reactivation and disease.

Pediatr Infect Dis J, 2000 Dec, 19(12), 1158 - 62
Factors associated with intestinal perforation in children's non-typhi Salmonella toxic megacolon; Chao HC et al.; BACKGROUND: To evaluate the risk factors for intestinal perforation in children with toxic megacolon caused by non-typhi Salmonella infection . METHODS: During an 11-year period we reviewed the records of children treated for non-typhi Salmonella infection . All of the subjects had positive stool culture for non-typhi Salmonella and were treated with intravenous ceftriaxone during hospitalization . Clinical data reviewed included demographic features, clinical manifestations, laboratory findings, radiologic findings, microbiology, therapeutic effect of hydration and rectal tube placement and the operative findings . Patients with toxic megacolon were defined as those having toxic appearance, diarrhea, high fever (>39 degrees C) and marked colon dilatation with maximal diameter > 1.5 times the width of the vertebra body of the first lumbar spine (L1-VB) . To define the risk factors for patients with toxic megacolon complicated by intestinal perforation, patients were divided into two groups for analysis: P group, those complicated with intestinal perforation; and NP group, those without intestinal perforation . Differences in age, sex, severity of diarrhea, duration of fever, hemogram and its differential, culture, stool analysis, serum C-reactive protein (CRP), electrolytes, maximal colon diameter, medical therapy and timing of rectal tube insertion between the two groups were analyzed . Statistical analyses were conducted with chi square tests and multiple logistic regression . RESULTS: A total of 75 patients (P group, 27 patients; NP group, 48 patients) ages 4 months to 6 years were evaluated . With chi square analysis 7 variables were found to be significantly associated with intestinal perforation: age >1 year; fever >5 days; ratio of immature to total neutrophils >20%; serum CRP >200 mg/l; colon diameter >2.5 times the width of L1-VB; inadequate early hydration; and delay in rectal tube insertion . With multivariate analysis age >1 year, serum CRP >200 mg/l and colon diameter >2.5 times of width of L1-VB, inadequate early hydration and delay in rectal tube insertion were the most significant factors associated with intestinal perforation . CONCLUSION: Identification of patients with toxic megacolon associated with non-typhi Salmonella infection at risk for further intestinal perforation is possible . Early effective fluid resuscitation and rectal tube insertion may be helpful to prevent the occurrence of intestinal perforation.

Dtsch Tierarztl Wochenschr, 2000 Oct, 107(10), 402 - 8
{Administration of autochthonous intestinal microflora--a method to prevent Salmonella infections in poultry}; Methner U; Administration of autochthonous intestinal microflora to chicks during the early period after hatching (Competitive Exclusion) is a widely accepted prophylactic method to control Salmonella infections in poultry . The method of competitive exclusion consists in an administration of intestinal flora from healthy adult birds to chicks during the first hours or days of their life . Use of competitive exclusion cultures will considerably enhance resistance to all Salmonella serovars colonising the chicken intestine and reduce shedding of salmonellas by infected animals . However, sole use of this method does not completely prevent Salmonella colonisation of the animals nor elimination of the agents from poultry flocks . At present, only complex competitive exclusion cultures whose composition has not been defined are capable of inducing an adequately high and reproducible efficacy . Effective preparations with a defined composition have not yet been developed because knowledge of the mechanisms of action of the competitive exclusion cultures as well as the effective species of the various bacterial genera is still inadequate . Since in approval procedures, the competitive exclusion cultures with a non-defined composition can neither be classified as medicines nor feed additives nor vaccines, WHO has proposed to establish the product category "Normal Gut Flora" (WHO, 1994) . Basic prerequisites for an effective reduction of non-host-adapted Salmonella serovars in, or their elimination from poultry flocks are the performance and assurance of effective hygienic measures . Like the methods of immunisation using live or inactivated Salmonella vaccines in poultry, the method of competitive exclusion constitutes an additional prophylactic method that may be applied directly in the animal to enhance its resistance to Salmonella infection.

Can J Microbiol, 2000 Dec, 46(12), 1149 - 52
The fliU and fliV genes are expressed as a single ORF in Salmonella choleraesuis; Ho KC et al.; A DNA fragment carrying flagellar genes was cloned from Salmonella choleraesuis . Compared to the corresponding DNA fragment of Salmonella muenchen, this fragment contained three ORFs instead of four shown in S . muenchen . The DNA sequence data showed that there was an insertion of nucleotide C in the ORF of the S . choleraesuis fliU gene, which resulted in the disappearance of a termination codon downstream . The recombinant plasmid pFU11 containing the coding region of the fliU gene made by PCR on S . choleraesuis genomic DNA was constructed and expressed in Escherichia coli in the presence of IPTG . As expected, a 45 kDa protein band was observed on a SDS-PAGE gel, in contrast to two with each having about a half of the molecular weight . These results demonstrated that the DNA sequence encoding one protein (FliU) in S . choleraesuis corresponded to the DNA sequence encoding two proteins (FliU and FliV) in S . muenchen . The protein encoded by this single ORF might carry out the functions of two separated proteins by folding in such a way that its conformation could function like two interdependent protein subunits.

Rofo, 2000 Nov, 172(11), 934 - 9
{Possible mutagenic effects of magnetic fields}; Teichmann EM et al.; AIM: To assess the potential mutagenic effect of static magnetic fields of 1.5 T and 7 T, gradient fields and high frequency magnetic fields . METHOD: We used the Salmonella mutagenicity test (Ames test), which detects mutations in a gene of a histidine-requiring (his-) strain to produce a histidine-independent (his+) strain, Exposure to a static magnetic field of 1.5 T and 7.2 T, in a bipolar magnetic gradient and additionally in a high frequency field took place with and without known genotoxic chemicals . RESULTS: No differences in the number of revertants between the bacterial strains of exposed and control cells could be detected and the exposure with known genotoxic chemicals showed no significant difference in mutagenicity . CONCLUSION: In conclusion our data do not provide evidence that exposure to a static magnetic field exerts effects on the mutagenicity in our standard tester strains and whether the exposure took place in a diagnostic 1.5 T MR scanner which is used in the clinical routine or at 7.2 T which is a much stronger field made no difference . Also an exposure in a gradient field or in a high frequency field did not show any alteration in the number of revertants.

Ann Ig, 2000 Jul-Aug, 12(4), 279 - 85
{Epidemiologic study and cost analysis of an Slamonella enteritidis epidemic}; Lopalco PL et al.; Salmonellosis is one of the most common forms of foodborne infection . An outbreak of gastroenteritidis associated with a wedding party was investigated, even to value the costs falling on individuals, the health services and society as a whole . One hundred and fifty nine wedding guests were interviewed by phone . Multivariate analysis was used to assess which food were significantly associated with infection . One hundred and thirteen cases were identified; ten stool samples were culture positive for Salmonella enteritidis . Handmade ice-cream and baba (a typical Italian pastry) were significantly associated with infection . The cost of a case was estimated to be between US $ 74 (for non hospitalised patients) and US $ 1,896 (for hospitalised patients) . The outbreak was caused by a strain of Salmonella enteritidis and the vehicle of infection were unpasteurised eggs used to prepare the ice-cream . The economic impact of this outbreak was considerable and mainly due to the hospitalisation.

Int J Food Microbiol, 2000 Dec 5, 62(1-2), 161 - 4
Incidence of Listeria spp . and Salmonella spp . in horsemeat for human consumption; de Assis MA et al.; The incidence of Salmonella spp., Listeria spp . and Listeria monocytogenes in horsemeat for human consumption was investigated . One-hundred and twenty-one samples of frozen horsemeat collected from two Brazilian abattoirs were analysed over a period of 1 year . Twenty-two samples (18.2%) were positive for Listeria spp . with nine (7.4%) containing L . monocytogenes . None of the samples harbored Salmonella spp.

Int J Food Microbiol, 2000 Dec 5, 62(1-2), 123 - 31
Survival and growth of Salmonella baildon in shredded lettuce and diced tomatoes, and effectiveness of chlorinated water as a sanitizer; Weissinger WR et al.; An outbreak of salmonellosis associated with diced tomatoes occurred in the United States in 1999 . Experiments were done to determine the efficacy of chlorine in killing Salmonella baildon, the causative serotype, inoculated onto shredded lettuce and diced tomatoes, and to determine survival characteristics of the organism on these produce items stored at 4 degrees C for up to 12 days and on tomatoes stored at 21 or 30 degrees C for up to 72 h . Populations of S . baildon in lettuce and tomatoes (pH 4.51 +/- 0.02) inoculated with 3.60 log10 and 3.86 log10 cfu/g, respectively, were reduced by less than 1 log when the produce was immersed for 40 s in a 120 or 200 microg/ml free chlorine solution . Produce inoculated with 0.60-0.86 log10 cfu/g was positive for the pathogen after treatment with 200 microg/ml chlorine . Initial populations of 3.28 and 3.40 log10 cfu/g of lettuce and tomatoes, respectively, decreased by about 2 log10 cfu/g during storage for 12 days at 4 degrees C . One of six samples of lettuce initially containing 0.28 log10 cfu of S . baildon per gram was positive after storage for 12 days, but the pathogen was not detected in tomatoes analyzed within 15 min of inoculation with 0.40 log10 cfu/g . While the number of viable cells decreased during storage at 4 degrees C, initial populations of 0.28 log10 cfu/g of shredded lettuce and 3.40 log10 cfu/g of diced tomatoes are not reduced to undetectable levels during storage at 4 degrees C for 12 days . Tolerance of S . baildon to an acidic pH (4.5) was not influenced by the pH (4.5, 5.8, or 7.2) of the medium in which it was grown, suggesting that this strain possesses unusual resistance to acid pH . The pathogen grew in diced tomatoes (pH 4.40 +/- 0.01) from an initial population of 0.79 log10 cfu/g to 5.32 and 7.00 log10 cfu/g within 24 h at 21 and 30 degrees C, respectively.

J Vasc Surg, 2001 Jan, 33(1), 106 - 13
Mycotic aneurysms of the thoracic and abdominal aorta and iliac arteries: experience with anatomic and extra-anatomic repair in 33 cases; Muller BT et al.; OBJECTIVE: A mycotic aneurysm of the aorta and adjacent arteries is a dreadful condition, threatening life, organs, and limbs . With regard to the aortic segment involved, repair by either in situ replacement or extra-anatomic reconstruction can be quite challenging . Even when surgery has been successful, the prognosis is described as very poor because of the weakened health status of the patient who has developed this type of aneurysm . The aim of our study was to find out whether any progress could be achieved in a single center over a long time period (18 years) through use of surgical techniques and antiseptic adjuncts . MATERIAL AND METHODS: From January 1983 to December 1999, a total of 2520 patients with aneurysms of the thoracic and abdominal aorta and iliac arteries underwent surgery for aortic or iliac replacement at our institution . During that period, 33 (1.31%) of these patients (mean age, 64.3 years) were treated for mycotic aneurysms of the lower descending and thoracoabdominal (n = 13), suprarenal (n = 4), and infrarenal (n = 10) aorta and iliac arteries (n = 6) . Twenty (61%) of these 33 patients had histories of various septic diseases; in the other 13 (39%), the etiology remained uncertain . Preoperative signs of infection, such as leukocytosis and elevated C-reactive protein, were found in 79% of the patients, and fever was apparent in 48%; 76% of the patients complained of pain . At the time of surgery, eight (24%) mycotic aneurysms were already ruptured, and 20 (61%) had penetrated into the periaortic tissues, forming a contained rupture . Five (15%) aneurysms were completely intact . The predominant microorganisms found in the aneurysm sac were Staphylococcus aureus and Salmonella species . Careful debridement of all infected tissue was essential . In the infrarenal aortic and iliac vascular bed, in situ reconstruction was performed only in cases of anticipated "low-grade" infection . Alternative revascularization with extra-anatomic procedures (axillobifemoral or femorofemoral crossover bypass graft) was carried out in eight of 16 cases . All four suprarenal and all 13 mycotic aneurysms of the thoracoabdominal aortic segment were repaired in situ . Antibiotics were administered perioperatively, and all patients were subsequently treated with long-term antibiotics . RESULTS: In-hospital mortality was 36% (n = 12) . Because of the smallness and heterogeneity of the sample, we could not demonstrate significant evidence for any influence of aneurysm location or type of reconstruction on patients' outcome . However, survival was clearly influenced by the status of rupture . During long-term follow-up (mean, 30 months; range, 1-139 months), 10 patients (48%) died-one (4.8%) probably as a consequence of the mycotic aneurysm, the others for unrelated reasons . Eleven patients (52%) are alive and well today, with no signs of persistent or recurrent infection . CONCLUSIONS: A mycotic aneurysm of the aortic iliac region remains a life-threatening condition, especially if the aneurysm has already ruptured by the time of surgery . Although the content of the aneurysm sac is considered septic, as was proved by positive cultures in 85% of our patients, in situ reconstruction is feasible and, surprisingly, was not more closely related to higher morbidity and mortality in our series than ligation and extra-anatomic reconstruction, although most of the aneurysms repaired in situ were located at the suprarenal and thoracoabdominal aorta . We assume that our operative mortality rate of 36%, which relates to a rupture rate of 85%, could be substantially lowered if the diagnosis of mycotic aneurysm were established before rupture.

J Clin Microbiol, 2001 Jan, 39(1), 201 - 6
Fluorescent amplified-fragment length polymorphism subtyping of the Salmonella enterica serovar enteritidis phage type 4 clone complex; Desai M et al.; Fluorescent amplified-fragment length polymorphism (FAFLP) analysis, a high-resolution PCR-based genome fingerprinting method, was used to subtype Salmonella enterica serovar Enteritidis phage type 4 . This single phage type is responsible for the majority of salmonellosis in Europe . Twenty strains isolated from nine outbreaks, five isolates from sporadic cases of human infection, four strains of poultry origin, and one laboratory-derived strain were comparatively studied by pulsed-field gel electrophoresis (PFGE) and FAFLP analysis . Following macrorestriction with XbaI, PFGE classified 73% of PT4 strains as a single type . FAFLP analysis was carried out with the primer pair EcoRI+0 and MseI+C, by simultaneously sampling 170 to 190 loci throughout the PT4 genome . Twenty-three FAFLP profiles, with 1 to 61 amplified-fragment differences, were found among the 30 strains . The index of discriminatory power of FAFLP analysis was 0.98, compared to 0.47 for PFGE . FAFLP analysis assigned genotypes to each PT4 outbreak, as well as sporadic PT4 infections, a significant development for the epidemiology and control of this zoonotic enteric pathogen.

J Clin Microbiol, 2001 Jan, 39(1), 154 - 61
Diversity of strains of Salmonella enterica serotype enteritidis from English poultry farms assessed by multiple genetic fingerprinting; Liebana E et al.; Reliable and sufficiently discriminative methods are needed for differentiating individual strains of Salmonella enterica serotype Enteritidis beyond the phenotypic level; however, a consensus has not been reached as to which molecular method is best suited for this purpose . In addition, data are lacking on the molecular fingerprinting of serotype Enteritidis from poultry environments in the United Kingdom . This study evaluated the combined use of classical methods (phage typing) with three well-established molecular methods (ribotyping, macrorestriction analysis of genomic DNA, and plasmid profiling) in the assessment of diversity within 104 isolates of serotype Enteritidis from eight unaffiliated poultry farms in England . The most sensitive technique for identifying polymorphism was PstI-SphI ribotyping, distinguishing a total of 22 patterns, 10 of which were found among phage type 4 isolates . Pulsed-field gel electrophoresis of XbaI-digested genomic DNA segregated the isolates into only six types with minor differences between them . In addition, 14 plasmid profiles were found among this population . When all of the typing methods were combined, 54 types of strains were differentiated, and most of the poultry farms presented a variety of strains, which suggests that serotype Enteritidis organisms representing different genomic groups are circulating in England . In conclusion, geographical and animal origins of Salmonella serotype Enteritidis isolates may have a considerable influence on selecting the best typing strategy for individual programs, and a single method cannot be relied on for discriminating between strains.

Braz J Infect Dis, 2000 Dec, 4(6), 279 - 83
Seasonal and age distribution of rotavirus infection in Porto Alegre--Brazil; Bittencourt JA et al.; Diarrhea is one of the most important causes of morbidity and mortality in countries with inadequate water sanitation, crowding and poverty . In this study we evaluated the rotavirus infection profile in Porto Alegre, Brazil . We analyzed the results of 603 laboratory tests obtained from patients who attended a private laboratory to investigate gastroenteritis during a 2 year period (from July 1996 to June 1998) . Rotavirus was identified as the causative agent in 42/312 (13.4%) of patients during the first year, and in 55/291 (18.9%) during the second year . Coproculture for Salmonella and Shigela was positive in only 6.6% of the patients . The prevalence of rotavirus was significantly higher in the winter season and inversely related to the average temperature . Children 7 months to 18 months of age were the most common group infected with rotavirus . The presence of leukocytes in the feces did not correlate with the occurrence of this disease . These results agree with other studies concerning the age group, season, and overall prevalence of rotavirus . The results confirm the need for new approaches to the prevention, diagnoses and management of this disease.

Braz J Infect Dis, 2000 Dec, 4(6), 275 - 8
Serial outbreaks of food-borne disease in Blumenau, Brazil, caused by Salmonella enteritidis; dos Santos SM et al.; This work describes the epidemic profile of outbreaks of food infection caused by Salmonella enteritidis, serogroup D, in the city of Blumenau, Federal State of Santa Catarina, Brazil, during the period between February, 1994, and June, 1997 . Ninety-six outbreaks were observed, and 79 (82%) were investigated, involving 7,802 people with signs and symptoms consistent with the infection . Most frequent symptoms were diarrhea (92%), abdominal pain (73%), fever (70%), vomiting (49%) and nausea (45%) . Mayonnaise was the food most frequently associated with the outbreaks, being the responsible vehicle in almost two thirds of the cases investigated . The outbreaks most frequently occurred at home (60%), but the largest number of infections resulted from industrial kitchens (78%) . The age group between 20 and 30 years was most affected . No relationships between the number of outbreaks and outside temperature or humidity were found . The attack rate showed no significant difference between men and women . Better attention to storage of food products at home and in industrial kitchens is needed to control this common gastrointestinal illness.

Mol Microbiol, 2001 Jan, 39(2), 248 - 59
A Salmonella inositol polyphosphatase acts in conjunction with other bacterial effectors to promote host cell actin cytoskeleton rearrangements and bacterial internalization; Zhou D et al.; A central feature of Salmonella pathogenicity is the bacterium's ability to enter into non-phagocytic cells . Bacterial internalization is the consequence of cellular responses characterized by Cdc42- and Rac-dependent actin cytoskeleton rearrangements . These responses are triggered by the co-ordinated function of bacterial proteins delivered into the host cell by a specialized protein secretion system termed type III . We report here that SopB, a Salmonella inositol polyphosphatase delivered to the host cell by this secretion system, mediates actin cytoskeleton rearrangements and bacterial entry in a Cdc42-dependent manner . SopB exhibits overlapping functions with two other effectors of bacterial entry, the Rho family GTPase exchange factors SopE and SopE2 . Thus, Salmonella strains deficient in any one of these proteins can enter into cells at high efficiency, whereas a strain lacking all three effectors is completely defective for entry . Consistent with an important role for inositol phosphate metabolism in Salmonella-induced cellular responses, a catalytically defective mutant of SopB failed to stimulate actin cytoskeleton rearrangements and bacterial entry . Furthermore, bacterial infection of intestinal cells resulted in a marked increase in Ins(1,4,5,6)P4, a consumption of InsP5 and the activation of phospholipase C . In agreement with the in vivo findings, purified SopB specifically dephosphorylated InsP5 to Ins(1,4,5,6)P4 in vitro . Surprisingly, the inositol phosphate fluxes induced by Salmonella were not caused exclusively by SopB . We show that the SopB-independent inositol phosphate fluxes are the consequence of the SopE-dependent activation of an endogenous inositol phosphatase . The ability of Salmonella to stimulate Rho GTPases signalling and inositol phosphate metabolism through alternative mechanisms is an example of the remarkable ability of this bacterial pathogen to manipulate host cellular functions.

J Clin Endocrinol Metab, 2000 Dec, 85(12), 4624 - 9
Changes in dehydroepiandrosterone (DHEA) and DHEA-sulfate plasma levels during experimental endotoxinemia in healthy volunteers; Schuld A et al.; Dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEA-S) have immunomodulatory effects in vitro and in vivo . Additionally, their plasma levels are altered during chronic infection and inflammation . However, it remains unknown whether these steroids are involved in early host responses to infection in humans . We examined DHEA and DHEA-S levels during experimental endotoxinemia, a well established pathophysiological model of bacterial infections in humans . Purified Salmonella abortus equi endotoxin (0.2, 0.4, or 0.8 ng/kg body weight) was injected in a single-blind, placebo-controlled experiment to 17 healthy male volunteers . During the following 12 h, rectal temperature and the plasma levels of ACTH, cortisol, DHEA, DHEA-S, interleukin 6, and tumor necrosis factor alpha were determined . Confirming earlier studies, temperature and cytokine levels showed monophasic, dose-dependent increases in response to endotoxin . In contrast, endocrinological effects of endotoxin showed a complex, biphasic pattern: cortisol levels were not affected by 0 . 2 ng/kg but significantly increased during the first 6 h following 0 . 4 and 0.8 ng/kg endotoxin, whereas ACTH and DHEA levels were significantly enhanced during the first 6 h following 0.8 ng/kg only . ACTH, DHEA, and cortisol secretion was blunted 6-12 h following 0.8 ng/kg . DHEA-S levels were unaffected during the first 6 h following all dosages, but between 6-12 h after injection they were significantly increased following 0.2 ng/kg, unaffected by 0.4 ng/kg, and significantly decreased following 0.8 ng/kg endotoxin . The present results suggest that similarly to glucocorticoids, the adrenal androgens DHEA and DHEA-S play an important role during early host responses to bacterial infections in humans.

J Bacteriol, 2001 Jan, 183(2), 611 - 20
Characterization of grvA, an antivirulence gene on the gifsy-2 phage in Salmonella enterica serovar typhimurium; Ho TD et al.; The lambdoid phage Gifsy-2 contributes significantly to Salmonella enterica serovar Typhimurium virulence . The phage carries the periplasmic superoxide dismutase gene, sodCI, and other unidentified virulence factors . We have characterized the gene grvA, a single open reading frame inserted in the opposite orientation in the tail operon of the Gifsy-2 phage . Contrary to what is observed with classic virulence genes, grvA null mutants were more virulent than wild type as measured by intraperitoneal competition assays in mice . We have termed this effect antivirulence . Wild-type grvA in single copy complemented this phenotype . However, grvA(+) on a multicopy plasmid also conferred the antivirulence phenotype . Neither a grvA null mutation nor the grvA(+) plasmid conferred a growth advantage or disadvantage in laboratory media . The antivirulence phenotype conferred by the grvA null mutation and the grvA(+) plasmid required wild-type sodCI but was independent of other virulence factors encoded on Gifsy-2 . These results suggest that in a wild-type situation, GrvA decreases the pathogenicity of serovar Typhimurium in the host, most likely by affecting resistance to toxic oxygen species . These virulence phenotypes were independent of functional Gifsy-2 phage production . Our data suggest that the contribution of Gifsy-2 is a complicated sum of both positive virulence factors such as sodCI and antivirulence factors such as grvA.

Appl Environ Microbiol, 2001 Jan, 67(1), 459 - 61
Application of rapid dot blot immunoassay for detection of Salmonella enterica serovar enteritidis in eggs, poultry, and other foods; Yoshimasu MA et al.; Salmonella enterica serovar Enteritidis was detected in artificially inoculated eggs within 24 h through a rapid monoclonal antibody-based dot blot immunoassay . Detection in poultry and other products required 28 h . Samples were directly enriched in homogenized egg without the need for pre- or postenrichment steps . Serovar Enteritidis was detected in the presence of other bacteria when outcompeted 1:400.

Appl Environ Microbiol, 2001 Jan, 67(1), 445 - 8
Relative distribution and conservation of genes encoding aminoglycoside-modifying enzymes in Salmonella enterica serotype typhimurium phage type DT104; Frana TS et al.; PCR was used to identify genes encoding aminoglycoside-modifying enzymes in 422 veterinary isolates of Salmonella enterica serotype Typhimurium . The identities of extra-integron genes encoding resistance to streptomycin, gentamicin, kanamycin, and apramycin were evaluated . Gentamicin resistance was conferred by the aadB gene . Kanamycin resistance was encoded by either the aphA1-Iab gene or the Kn gene . Apramycin resistance was determined by the aacC4 gene . Analysis of gene distribution did not reveal significant differences with regard to phage type, host species, or region except for the Kn gene, which was found mostly in nonclinical isolates . The data from this study indicate that pentaresistant DT104 does not acquire extra-integron genes in species- or geography-related foci, which supports the hypothesis that clonal expansion is the method of spread of this organism.

Appl Environ Microbiol, 2001 Jan, 67(1), 217 - 24
Development and optimization of a novel immunomagnetic separation- bacteriophage assay for detection of Salmonella enterica serovar enteritidis in broth; Favrin SJ et al.; Salmonella is the second-leading cause of food-borne illness in most developed countries, causing diarrhea, cramps, vomiting, and often fever . Many rapid methods are available for detection of Salmonella in foods, but these methods are often insensitive or expensive or require a high degree of technical ability to perform . In this paper we describe development and characterization of a novel assay that utilizes the normal infection cycle of bacteriophage SJ2 for detection of Salmonella enterica serovar Enteritidis in broth . The assay consists of four main stages: (i) capture and concentration of target cells by using immunomagnetic separation (IMS); (ii) infection of the target bacterium with phage; (iii) amplification and recovery of progeny phage; and (iv) assay of progeny phage on the basis of their effect on a healthy population of host cells (signal-amplifying cells) . The end point of the assay can be determined by using either fluorescence or optical density measurements . The detection limit of the assay in broth is less than 10(4) CFU/ml, and the assay can be performed in 4 to 5 h . The results of this study demonstrate that the IMS-bacteriophage assay is a rapid, simple, and sensitive technique for detection of Salmonella serovar Enteritidis in broth cultures which can be applied to preenriched food samples.

Indian J Pediatr, 2000 Feb, 67(2 Suppl), S58 - 62
Recent advances in improved tuberculosis vaccines; McMurray DN; Tuberculosis continues to be a major infectious cause of global morbidity and mortality, both in children and adults, in spite of widespread vaccination of infants with Bacille Calmette-Guerin (BCG) and the availability of effective antibiotics . The failure of BCG to significantly affect disease incidence in adults in many endemic countries, combined with the growing HIV epidemic and the appearance of multidrug resistant strains of Mycobacterium tuberculosis, threatens to overwhelm current tuberculosis control strategies . This unfortunate state of affairs has driven an intensive search for better tuberculosis vaccines . This article reviews the various vaccine development strategies which are being used e.g., purification or synthesis of protein peptide and non-peptide antigens from M . tuberculosis, creation of rationally-attenuated mutants of BCG and M . tuberculosis, development of DNA vaccines based upon the published genome sequence, the cloning of mycobacterial genes into living vaccine carrier strains (e.g., attenuated Salmonella, vaccinia virus, etc), or the use of naturally attenuated mycobacterial species (e.g., M . vaccae, M . microti) . The animal models in which these vaccine candidates are being screened for protective efficacy (e.g., the mouse, guinea pig, rabbit, primate) will be discussed briefly . Finally, some of the challenges inherent in the eventual clinical evaluation of new tuberculosis vaccines are reviewed.

J Vet Med Sci, 2000 Nov, 62(11), 1139 - 43
Induction of early immunopotentiation to Fimbriae of Salmonella Enteritidis (SE) by administering thymulin and zinc to SE-vaccinated chicken breeders: relationship to protection; Barbou EK et al.; The purpose of this study is to attempt the induction of early immunopotentiation of antibodies specific to fimbriae of Salmonella enterica serovar Enteritidis (SE), by administering thymulin and zinc to SE-vaccinated chicken breeders, and the improvement of protection against a controlled-live challenge by SE . The first two groups of breeders were administered subcutaneously at 15 and 19 weeks of age a killed SE vaccine . Breeders of the third and fourth groups were left unvaccinated . Breeders of the first group, immunopotentiated by thymulin and zinc, were able to induce the earliest antibodies in their pooled sera at 2 weeks post the first SE-vaccination, specific to fimbriae (approximately 21 KDa) of SE . However, the second group that was only vaccinated with the same SE-vaccine produced specific antibodies to fimbriae at 3 weeks following the second vaccination (22 weeks of age) . Breeders of the third group, that were neither SE-vaccinated nor immunopotentiated by thymulin and zinc, but were challenged by live SE at 22 weeks of age, were able to show specific antibodies to fimbriae at 3 weeks post challenge (25 weeks of age) . The fourth group that was deprived of SE-vaccination, immunopotentiators, and challenge didn't show any background antibodies specific to SE-fimbriae . The presence of the earliest antibody-immunopotentiation to fimbriae of SE in breeders of the first group, administered thymulin and zinc, was associated with the lowest frequency of SE-infected ceca (10%) among the challenged groups . In addition, breeders of the first group were the only challenged birds resulting in absence of SE infection in their cecal tonsils . The first group-vaccinated, immunopotentiated, and challenged, and the second group-vaccinated and challenged only resulted in breeders with absence of SE infection in their oviducts and spleens . In conclusion, immunopotentiation of chicken breeders by thymulin and zinc induces the earliest specific antibodies to fimbriae of SE associated with the lowest frequency of SE-infected ceca, and absence of SE infection from cecal tonsils, oviducts and spleens.

J Clin Pathol, 2000 Nov, 53(11), 851 - 3
The serodiagnosis of infection with Salmonella typhi; Chart H et al.; BACKGROUND/AIMS: The serodiagnosis of infection with Salmonella typhi, using the Widal agglutination assay, relies on patients' antibodies to the O = 9,12 lipopolysaccharide (LPS) antigens, H = d flagellar antigens, and the Vi capsular antigens . A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection with S typhi . In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens . METHODS: The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale . Antibodies to the Vi capsular antigen were detected using a standard preparation of S typhi, ViI Bhatnagar variant strain (S typhi, ViI) . Sera used in the study comprised 73 from patients who were culture positive for S typhi, 10 from patients who were culture positive for other species of Salmonella not expressing a Vi antigen (namely, S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly, or S mbandaka), and eight from healthy blood donors . RESULTS: Agglutination titres of > or = 1/40 were detected to S typhi ViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen . The Widal assay also detected significant amounts of agglutinating antibodies to S . typhi ViI in all eight control sera and seven sera from patients infected with S bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley . CONCLUSIONS: Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable . The serodiagnosis of infections with S typhi should be based on the detection of antibodies to both the O = 9,12 LPS antigen and the H = d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay . Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid.

Tumour Biol, 2001 Mar-Apr, 22(2), 67 - 71
Influence of AFP, CEA and PSA on the in vitro production of cytokines; Filella X et al.; Several studies have demonstrated a decreased cytokine production in patients with cancer . Likewise, there is some evidence showing that tumor markers may play a role in immunoregulation . In this work, we have studied the in vitro production of IL-1beta, IL-6 and TNF-alpha in whole-blood cell cultures of 10 healthy subjects after polyclonal activation with lipopolysaccharide of Salmonella enteridis and phytohemagglutinin in the presence or absence of three markers, AFP, CEA and PSA . Each sample was incubated for 48 h at 37 degrees C in a humidified atmosphere of 5% CO(2) . Subsequently, cytokine levels in the supernatant were determined . AFP did not significantly affect the production of the three cytokines compared to the basal value obtained on adding PBS . In contrast, CEA significantly increased the production of IL-6 (p <0.001) and TNF-alpha (p = 0.002), while PSA significantly decreased IL-1beta (p <0.001), IL-6 (p = 0.031) and TNF-alpha (p <0.0001) production . These results suggest a possible role of CEA and PSA in the production of these cytokines .

Lett Appl Microbiol, 2000 Dec, 31(6), 443 - 8
Improvement in Salmonella detection in milk and dairy products: comparison between the ISO method and the Oxoid SPRINT Salmonella test; Richter J et al.; The Oxoid SPRINT Salmonella test was compared with the ISO method (ISO 6579: 1993) for the detection of Salmonella in milk and dairy products . Samples were artificially contaminated, in some cases with sublethally injured salmonellas . Experiments with raw milk, soft cheese made from heat-treated milk (mould-ripened and with smear) and soft cheese with smear made from raw milk showed no significant differences between the SPRINT and ISO methods . With dried milk products and mould-ripened soft cheese made from raw milk the reference method gave significantly more positive results . The addition of ferrioxamine E to pre-enrichment (ISO) or pre-enrichment/enrichment broth (SPRINT test) did not improve Salmonella detection.

Antimicrob Agents Chemother, 2001 Jan, 45(1), 38 - 43
A soxRS-constitutive mutation contributing to antibiotic resistance in a clinical isolate of Salmonella enterica (Serovar typhimurium); Koutsolioutsou A et al.; The soxRS regulon is activated by redox-cycling drugs such as paraquat and by nitric oxide . The >15 genes of this system provide resistance to both oxidants and multiple antibiotics . An association between clinical quinolone resistance and elevated expression of the soxRS regulon has been observed in Escherichia coli, but this association has not been explored for other enteropathogenic bacteria . Here we describe a soxRS-constitutive mutation in a clinical strain of Salmonella enterica (serovar Typhimurium) that arose with the development of resistance to quinolones during treatment . The elevated quinolone resistance in this strain derived from a point mutation in the soxR gene and could be suppressed in trans by multicopy wild-type soxRS . Multiple-antibiotic resistance was also transferred to a laboratory strain of S . enterica by introducing the cloned mutant soxR gene from the clinical strain . The results show that constitutive expression of soxRS can contribute to antibiotic resistance in clinically relevant S . enterica.

J Immunol, 2000 Dec 15, 165(12), 7234 - 9
Up-regulation of the IL-12 receptor beta 2 chain in Crohn's disease; Parrello T et al.; Crohn' s disease (CD) is a chronic intestinal inflammatory disorder characterized by aberrant mucosal Th1 cell activation and production of IL-12, the major Th1-driving factor . The T cell response to IL-12 is dependent on the expression of a specific receptor composed of two subunits, termed IL-12Rbeta1 and IL-12Rbeta2 . The content of IL-12Rbeta2, as measured at the mRNA level, is crucial in regulating Th1 differentiation . In this study we therefore investigated IL-12Rbeta2 RNA transcripts in CD . IL-12Rbeta2 expression was increased in active CD as well as Helicobacter pylori (HP)-associated gastritis and Salmonella colitis compared with that in inactive CD, ulcerative colitis, noninflammatory controls, and celiac disease . In contrast, IL-12Rbeta1 transcripts were expressed at comparable levels in all samples . In CD, IL-12Rbeta2 expression strictly correlated with tyrosine phosphorylation of STAT4, a key component of the IL-12-dependent Th1 polarization . This was associated with a pronounced expression of IFN-gamma . Transcripts for IL-12/p40 were detected in CD, HP-positive, and Salmonella colitis patients, but not in celiac disease, indicating that IL-12Rbeta2 up-regulation occurs only in IL-12-associated Th1 gastrointestinal diseases . Finally, we showed that stimulation of lamina propria mononuclear cells with IL-12 enhanced IL-12Rbeta2, suggesting that IL-12 regulates IL-12Rbeta2 expression in human gastrointestinal mucosa . The data show that the signaling pathway used by IL-12 to induce Th1 differentiation is increased at the site of disease in CD, further supporting the view that IL-12/IL-12R signals contribute to the inflammatory response in this condition.

J Surg Res, 2001 Jan, 95(1), 44 - 9
Use of rifampin-soaked gelatin-sealed polyester grafts for in situ treatment of primary aortic and vascular prosthetic infections; Bandyk DF et al.; BACKGROUND: In situ treatment of artery/graft infection has distinct advantages compared to vessel excision and extra-anatomic bypass procedures . Based on animal studies of a rifampin-soaked, gelatin-impregnated polyester graft that demonstrated prolonged in vivo antibacterial activity, this antibiotic-bonded graft was used selectively in patients for in situ treatment of low-grade Gram-positive prosthetic graft infections or primary aortic infections not amenable to excision and ex situ bypass . METHODS: In a 5-year period (1995-1999), 27 patients with prosthetic graft infection (aortofemoral, n = 18, femorofemoral, n = 3; axillofemoral, n = 1) or primary aortic infection (mycotic aneurysm, n = 3; infected AAA, n = 2) underwent excision of the infected vessel and in situ replacement with a rifampin soaked (45-60 mg/ml for 15 min) gelatin-impregnated polyester graft . All prosthetic graft infections were low grade in nature, caused Gram-positive bacteria (Staphylococcus epidermidis, 16; Staphylococcus aureus, 5; Streptococcus, 1), and were treated electively . Patients with mycotic aortic aneurysm presented with sepsis and underwent urgent or emergent surgery . RESULTS: Two (8%) patients died-1 as a result of a ruptured Salmonella mycotic aortic aneurysm and the other from methicillin-resistant S . aureus infection following deep vein replacement of an in situ replaced femorofemoral graft . No amputations or late deaths as the result of vascular infection occurred in the 25 surviving patients . Two patients developed recurrent infection caused by a rifampin-resistant S . epidermidis in a replaced aortofemoral graft limb and were successfully treated with graft excision and in situ autogenous vein replacement . Eighteen patients remain alive and clinically free of infection after a mean follow-up interval of 17 months . CONCLUSIONS: In situ replacement treatment using a rifampin-bonded prosthetic graft for low-grade staphylococcal arterial infection was safe, durable, and associated with eradication of clinical signs of infection . Failure of this therapy was the result of virulent and antibiotic-resistant bacterial strains .

J Infect, 2000 Nov, 41(3), 256 - 9
Non-typhoidal Salmonella bacteraemia without gastroenteritis: a marker of underlying immunosuppression . Review Of cases at St . Thomas' Hospital 1970-1999; Brown M et al.; OBJECTIVES: To classify non-typhoidal salmonella bacteraemia according to clinical presentation, and to study how this correlates with the presence of underlying immunosuppression . METHODS: We analysed data collected prospectively for all 82 cases of non-typhoidal salmonella bacteraemia presenting to St . Thomas' Hospital between 1970 and 1999 . RESULTS: Patients presented with one of three syndromes: diarrhoea, an extra-intestinal focus of infection, or isolated fever with no focus . Only 18% of those with diarrhoea had underlying immunosuppression, compared with 80% of those with extra-intestinal focal infections (P= 0.001) and 80% of those with no focus (P= 0.0001) . There was no significant association between salmonella serotype and underlying immunosuppression . Salmonella enteritidis isolates, especially phage type 4, increased significantly during the last decade (P= 0.001) . The presentation of non-typhoidal salmonella bacteraemia in the absence of diarrhoea prompted the diagnosis of HIV in two patients . CONCLUSION: Underlying immunosuppression should be excluded in patients presenting with non-typhoidal salmonella bacteraemia in the absence of gastroenteritis . This may lead to an earlier diagnosis of HIV .

Infect Immun, 2001 Jan, 69(1), 556 - 8
Immunity against Helicobacter pylori: significance of interleukin-4 receptor alpha chain status and gender of infected mice; Aebischer T et al.; Vaccination of interleukin-4 (IL-4) receptor alpha (IL-4Ralpha) chain-deficient BALB/c mice with Helicobacter pylori urease and cholera toxin or with urease-expressing, live attenuated Salmonella enterica serovar Typhimurium cells revealed that protection against H . pylori infection is independent of IL-4- or IL-13-mediated signals . A comparison of male and female mice suggests a sexual dimorphism in the extent of bacterial colonization that is particularly evident in the absence of the IL-4Ralpha chain.

Infect Immun, 2001 Jan, 69(1), 547 - 50
Aromatic compound-dependent Brucella suis is attenuated in both cultured cells and mouse models; Foulongne V et al.; The aroC gene of the facultative intracellular pathogen Brucella suis was cloned and sequenced . The cloned aroC gene complements Escherichia coli and Salmonella enterica serovar Typhimurium aroC mutants . A B . suis aroC mutant was found to be unable to grow in a defined medium without aromatic compounds . The mutant was highly attenuated in tissue culture (THP1 macrophages and HeLa cells) and murine virulence models.

Infect Immun, 2001 Jan, 69(1), 463 - 71
Improved innate immunity of endotoxin-tolerant mice increases resistance to Salmonella enterica serovar typhimurium infection despite attenuated cytokine response; Lehner MD et al.; During infection with gram-negative bacteria, exposure of immune cells to lipopolysaccharide (LPS) from the bacterial cell membrane induces a rapid cytokine response which is essential for the activation of host defenses against the invading pathogens . Administration of LPS to mice induces a state of hyporesponsiveness, or tolerance, characterized by reduced cytokine production upon subsequent LPS challenge . In the model of experimental Salmonella enterica serovar Typhimurium infection of mice, we assessed the question of whether complete LPS tolerance induced by repetitive doses of LPS interfered with cytokine production and host defense against gram-negative bacteria . Although production of various cytokines in response to serovar Typhimurium was attenuated by LPS pretreatment, LPS-tolerant mice showed improved antibacterial activity, evidenced by a prolongation of survival and a continuously lower bacterial load . We attribute this protective effect to three independent mechanisms . (i) Peritoneal accumulation of leukocytes in the course of LPS pretreatment accounted for enhanced defense against serovar Typhimurium during the first 6 h of infection but not for decreased bacterial load in late-stage infection . (ii) LPS-tolerant mice had an increased capacity to recruit neutrophilic granulocytes during infection . (iii) LPS-tolerant mice showed threefold-increased Kupffer cell numbers, enhanced phagocytic activity of the liver, and strongly improved clearance of blood-borne serovar Typhimurium . These results demonstrate that despite attenuated cytokine response, acquired LPS tolerance is associated with enhanced resistance to infections by gram-negative bacteria and that this effect is mainly mediated by improved effector functions of the innate immune system.

Infect Immun, 2001 Jan, 69(1), 367 - 77
Salmonella pathogenicity island 2 influences both systemic salmonellosis and Salmonella-induced enteritis in calves; Bispham J et al.; We have used signature-tagged mutagenesis to identify mutants of the host-specific Salmonella enterica serotype Dublin which were avirulent in calves and/or BALB/c mice . A mutant with a transposon insertion in the sseD gene of Salmonella pathogenicity island 2 (SPI-2), which encodes a putative secreted effector protein, was identified . This mutant was recovered from the bovine host but not from the murine host following infection with a pool of serotype Dublin mutants . However, a pure inoculum of the sseD mutant was subsequently shown to be attenuated in calves following infection either by the intravenous route or by the oral route . The sseD mutant was fully invasive for bovine intestinal mucosa but was subsequently unable to proliferate to the same numbers as the parental strain in vivo . Both the sseD mutant and a second SPI-2 mutant, with a transposon insertion in the ssaT gene, induced significantly weaker secretory and inflammatory responses in bovine ligated ileal loops than did the parental strain . These results demonstrate that SPI-2 is required by serotype Dublin for the induction of both systemic and enteric salmonellosis in calves.

Infect Immun, 2001 Jan, 69(1), 204 - 12
Salmonella enterica serotype typhimurium elicits cross-immunity against a Salmonella enterica serotype enteritidis strain expressing LP fimbriae from the lac promoter; Nicholson TL et al.; The biological significance of fimbrial phase variation in Salmonella serotypes is currently unknown . Exposure to long polar (LP) fimbriae of Salmonella enterica serotype Typhimurium results in selection against lpf phase ON cells of serotype Enteritidis during a subsequent challenge, suggesting that fimbrial phase variation may be a mechanism to evade cross-immunity between Salmonella serotypes . This notion was tested by assessing the effect of an immune response against serotype Typhimurium LP fimbriae on colonization of mice with a serotype Enteritidis mutant in which the lpf promoter region was replaced with the Escherichia coli lac promoter . During a challenge with a serotype Enteritidis mutant carrying the lac promoter in front of the lpf operon, significantly lower numbers were recovered from organs and feces of mice previously immunized with an lpf phase ON culture of serotype Typhimurium than from mice not previously exposed to LP fimbriae . Immunization with the lpf phase ON culture of serotype Typhimurium elicited antibodies that cross-reacted with a purified gluthathione-S-transferase-LpfA fusion protein of serotype Enteritidis . These data suggested that cross-immunity against LP fimbrial proteins cannot be evaded if phase variation on the transcriptional level is prevented by expressing the lpf operon from the lac promoter . These data hence support the idea that phase variation of LP fimbriae is a mechanism to evade cross-immunity between serotypes Enteritidis and Typhimurium.

Vet Microbiol, 2001 Jan 5, 78(1), 61 - 77
Analysis of expression of flagella by Salmonella enterica serotype typhimurium by monoclonal antibodies recognising both phase specific and common epitopes; Sojka M et al.; Monoclonal antibodies specific for phase 1 ("i" antigen), phase 2 ("1,2" antigen) and common epitopes of the flagellins of Salmonella enterica serotype Typhimurium were raised . Having confirmed their specificity, the monoclonal antibodies were used to develop semi-quantitative ELISAs in order to assess the relative expression of the two phases by strains of Typhimurium . The majority of Typhimurium strains representative of a wide cross-section of definitive types from animal and environmental sources preferentially expressed phase 1 antigen in vitro . DT40 strains were unique in expressing phase 2 preferentially . The ratio of phase 1 to phase 2 expressed by strains tended to be constant for any one strain when strains were grown on a number of conventional laboratory media . However, the ratio of phases was shown to be modulated by incubation at 42 degrees C and buffering media at pH values, notably 4.5, other than neutral . Selenite broth and Rambach media repressed flagellation.

J Bacteriol, 2001 Jan, 183(1), 336 - 46
Methionine-to-cysteine recycling in Klebsiella aerogenes; Seiflein TA et al.; In the enteric bacteria Escherichia coli and Salmonella enterica, sulfate is reduced to sulfide and assimilated into the amino acid cysteine; in turn, cysteine provides the sulfur atom for other sulfur-bearing molecules in the cell, including methionine . These organisms cannot use methionine as a sole source of sulfur . Here we report that this constraint is not shared by many other enteric bacteria, which can use either cysteine or methionine as the sole source of sulfur . The enteric bacterium Klebsiella aerogenes appears to use at least two pathways to allow the reduced sulfur of methionine to be recycled into cysteine . In addition, the ability to recycle methionine on solid media, where cys mutants cannot use methionine as a sulfur source, appears to be different from that in liquid media, where they can . One pathway likely uses a cystathionine intermediate to convert homocysteine to cysteine and is induced under conditions of sulfur starvation, which is likely sensed by low levels of the sulfate reduction intermediate adenosine-5'-phosphosulfate . The CysB regulatory proteins appear to control activation of this pathway . A second pathway may use a methanesulfonate intermediate to convert methionine-derived methanethiol to sulfite . While the transsulfurylation pathway may be directed to recovery of methionine, the methanethiol pathway likely represents a general salvage mechanism for recovery of alkane sulfide and alkane sulfonates . Therefore, the relatively distinct biosyntheses of cysteine and methionine in E . coli and Salmonella appear to be more intertwined in Klebsiella.

J Bacteriol, 2001 Jan, 183(1), 328 - 35
Alternative pathways for siroheme synthesis in Klebsiella aerogenes; Kolko MM et al.; Siroheme, the cofactor for sulfite and nitrite reductases, is formed by methylation, oxidation, and iron insertion into the tetrapyrrole uroporphyrinogen III (Uro-III) . The CysG protein performs all three steps of siroheme biosynthesis in the enteric bacteria Escherichia coli and Salmonella enterica . In either taxon, cysG mutants cannot reduce sulfite to sulfide and require a source of sulfide or cysteine for growth . In addition, CysG-mediated methylation of Uro-III is required for de novo synthesis of cobalamin (coenzyme B(12)) in S . enterica . We have determined that cysG mutants of the related enteric bacterium Klebsiella aerogenes have no defect in the reduction of sulfite to sulfide . These data suggest that an alternative enzyme allows for siroheme biosynthesis in CysG-deficient strains of Klebsiella . However, Klebsiella cysG mutants fail to synthesize coenzyme B(12), suggesting that the alternative siroheme biosynthetic pathway proceeds by a different route . Gene cysF, encoding an alternative siroheme synthase homologous to CysG, has been identified by genetic analysis and lies within the cysFDNC operon; the cysF gene is absent from the E . coli and S . enterica genomes . While CysG is coregulated with the siroheme-dependent nitrite reductase, the cysF gene is regulated by sulfur starvation . Models for alternative regulation of the CysF and CysG siroheme synthases in Klebsiella and for the loss of the cysF gene from the ancestor of E . coli and S . enterica are presented.

J Bacteriol, 2001 Jan, 183(1), 77 - 85
Identification of residues involved in catalytic activity of the inverting glycosyl transferase WbbE from Salmonella enterica serovar borreze; Keenleyside WJ et al.; Synthesis of the O:54 O antigen of Salmonella enterica is initiated by the nonprocessive glycosyl transferase WbbE, assigned to family 2 of the glycosyl transferase enzymes (GT2) . GT2 enzymes possess a characteristic N-terminal domain, domain A . Based on structural data from the GT2 representative SpsA (S . J . Charnock and G . J . Davies, Biochemistry 38:6380-6385, 1999), this domain is responsible for nucleotide binding . It possesses two invariant Asp residues, the first forming a hydrogen bond to uracil and the second coordinating a Mn(2+) ion . Site-directed replacement of Asp41 (D41A) of WbbE, the analogue of the first Asp residue of SpsA, revealed that this is not required for activity . WbbE possesses three Asp residues near the position analogous to the second conserved residue . Whereas D95A reduced WbbE activity, activity in D93A and D96A mutants was abrogated, suggesting that either D93 or D96 may coordinate the Mn(2+) ion . Our studies also identified a C-terminal region of sequence conservation in 22 GT2 members, including WbbE . SpsA was not among these . This region is characterized by an ED(Y) motif . The Glu and Asp residues of this motif were individually replaced in WbbE . E180D in WbbE had greatly reduced activity, and an E180Q replacement completely abrogated activity; however, D181E had no effect . E180 is predicted to reside on a turn . Combined with the alignment of the motif with potential catalytic residues in the GT2 enzymes ExoM and SpsA, we speculate that E180 is the catalytic residue of WbbE . Sequence and predicted structural divergence in the catalytic region of GT2 members suggests that this is not a homogeneous family.

Mutat Res, 2000 Nov 20, 455(1-2), 61 - 9
The bacterial tryptophan reverse mutation assay with Escherichia coli WP2; Mortelmans K et al.; The Escherichia coli WP2 tryptophan reverse mutation assay detects trp(-) to trp(+) reversion at a site blocking a step in the biosynthesis of tryptophan prior to the formation of anthranilic acid . The different WP2 strains all carry the same AT base pair at the critical mutation site within the trpE gene . The assay is currently used by many laboratories in conjunction with the Ames Salmonella assay for screening chemicals for mutagenic activity . In general the WP2 strains are used as a substitute for, or as an addition to Salmonella strain TA102 which also carries an AT base pair at the mutation site . The assay is also recommended together with the Ames assay for data submission to regulatory agencies . National and international guidelines have been established for performing these mutagenicity assays.The E . coli WP2 assay procedures are the same as those described elsewhere in this volume for the Ames Salmonella assay (Mortelmans and Zeiger, 2000) with the exception that limited tryptophan instead of limited histidine is used . This chapter is an addendum to the previous chapter and the reader should refer to the previous chapter for details regarding experimental procedures and assay design.

Mutat Res, 2000 Nov 20, 455(1-2), 29 - 60
The Ames Salmonella/microsome mutagenicity assay; Mortelmans K et al.; The Ames Salmonella/microsome mutagenicity assay (Salmonella test; Ames test) is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances that can produce genetic damage that leads to gene mutations . The test employs several histidine dependent Salmonella strains each carrying different mutations in various genes in the histidine operon . These mutations act as hot spots for mutagens that cause DNA damage via different mechanisms . When the Salmonella tester strains are grown on a minimal media agar plate containing a trace of histidine, only those bacteria that revert to histidine independence (his(+)) are able to form colonies . The number of spontaneously induced revertant colonies per plate is relatively constant . However, when a mutagen is added to the plate, the number of revertant colonies per plate is increased, usually in a dose-related manner . The Ames test is used world-wide as an initial screen to determine the mutagenic potential of new chemicals and drugs . The test is also used for submission of data to regulatory agencies for registration or acceptance of many chemicals, including drugs and biocides . International guidelines have been developed for use by corporations and testing laboratories to ensure uniformity of testing procedures . This review provides historical aspects of how the Ames was developed and detailed procedures for performing the test, including the design and interpretation of results.

Mutat Res, 2000 Nov 20, 455(1-2), 21 - 8
Practical aspects of mutagenicity testing strategy: an industrial perspective; Gollapudi BB et al.; Genetic toxicology studies play a central role in the development and marketing of new chemicals for pharmaceutical, agricultural, industrial, and consumer use . During the discovery phase of product development, rapid screening tests that require minimal amounts of test materials are used to assist in the design and prioritization of new molecules . At this stage, a modified Salmonella reverse mutation assay and an in vitro micronucleus test with mammalian cell culture are frequently used for screening . Regulatory genetic toxicology studies are conducted with a short list of compounds using protocols that conform to various international guidelines . A set of four assays usually constitutes the minimum test battery that satisfies global requirements . This set includes a bacterial reverse mutation assay, an in vitro cytogenetic test with mammalian cell culture, an in vitro gene mutation assay in mammalian cell cultures, and an in vivo rodent bone marrow micronucleus test . Supplementary studies are conducted in certain instances either as a follow-up to the findings from this initial testing battery and/or to satisfy a regulatory requirement . Currently available genetic toxicology assays have helped the scientific and industrial community over the past several decades in evaluating the mutagenic potential of chemical agents . The emerging field of toxicogenomics has the potential to redefine our ability to study the response of cells to genetic damage and hence our ability to study threshold phenomenon.

Microbes Infect, 2000 Nov, 2(13), 1567 - 78
Diagnosis of defects in the type 1 cytokine pathway; Lammas DA et al.; Patients with inherited defects in the interleukin-12 (IL-12)-dependent, 'high-output' interferon-gamma (IFN-gamma) pathway exhibit selective susceptibility to poorly pathogenic mycobacterial and salmonella infections . This review summarises the extended clinical spectrum seen in this group of patients and indicates a strategy for the identification of putative defects in the type 1 cytokine pathway.

Microbes Infect, 2000 Nov, 2(13), 1559 - 66
Human deficiencies in type 1 cytokine receptors reveal the essential role of type 1 cytokines in immunity to intracellular bacteria; Ottenhoff TH et al.; Studies on patients with idiopathic, severe infections due to poorly pathogenic mycobacteria and Salmonella have revealed that many of these patients are unable to produce or respond to interferon-gamma (IFN-gamma) . This inability results from causative, deleterious genetic mutations in either one of four different genes in the type 1 cytokine cascade, encoding interleukin-12Rbeta1 (IL-12Rbeta1), IL-12p40, IFN-gammaR1 or IFN-gammaR2 . The immunological phenotypes resulting from the seven groups of complete or partial deficiencies in type 1 cytokine (receptor) genes that have been distinguished thus far will be summarized and discussed, and placed in a broader context in relation to disease susceptibility.

Dev Comp Immunol, 2001 Mar, 25(2), 159 - 68
Induction of the respiratory burst in turtle peritoneal macrophages by Salmonella muenchen; Pasmans F et al.; Peritoneal macrophages were collected from juvenile turtles 72h after intraperitoneal inoculation with a 3% Sephadex suspension . The macrophages were assayed for their chemiluminescent (CL) properties, reflecting their respiratory burst activity, after stimulation with Zymosan A, phorbol 12-myristate 13-acetate (PMA), N-formyl-methionyl-leucyl-phenylalanine (fMLP), and calcium ionophore A23187 . Except for fMLP, all triggering agents induced a marked CL response . Luminol was used as the chemiluminescent probe . When comparing CL responses in temperatures ranging from 15 to 35 degrees C, lower assay temperatures induced lower and slower CL responses . Stimulation with viable Salmonella muenchen resulted in a distinct response . Bacteria, inactivated by means of heat or acetone, induced a faster and stronger oxidative burst . Opsonization of either viable or heat-inactivated S . muenchen with non-inactivated anti-S . muenchen serum, prepared in turtles, induced faster and higher CL responses . On the other hand, opsonization of acetone-inactivated S . muenchen caused CL responses to be slower and weaker . S . muenchen, opsonized with heat-inactivated turtle anti S . muenchen serum, induced higher responses than non-opsonized bacteria, but slower and weaker responses than bacteria opsonized with native turtle antiserum . No response was recorded after stimulation with LPS and the supernatant of heat-inactivated bacteria.

Int J Hyg Environ Health, 2000 Oct, 203(2), 117 - 26
GIS-supported investigation of a nosocomial Salmonella outbreak; Kistemann T et al.; Within an outbreak at a university hospital 102 persons (44 patients, 26 nursery school children and one relative as well as 31 employees) have been diagnosed to be infected by Salmonella enteritidis . Ninety-nine persons complied with the "primary case"-definition . The source of infection could not be detected in retrospect by hygienic-microbiological methods due to missing food samples . But GIS (Geographical Information System)-supported epidemiological investigation and analysis of food production showed that most likely vanilla pudding had been the vehicle of infection . Contamination of the pudding could be put down to the fact that its production took place in direct spatial and temporal association with the preparation of turkey . Probably further infections caused by this primary source were avoided by immediate measures . The making out of an HACCP-concept as well as structural and technical short-term redevelopment measures proved to be decisive factors to decrease the risk of further infections . From these experiences, some recommendations could be derived for the investigation of food-borne outbreaks in hospitals.

Int Microbiol, 1999 Jun, 2(2), 115 - 7
A rapid procedure for the isolation of plasmid DNA from environmental bacteria; Ferrus MA et al.; The INSTA-MINI-PREP method, a rapid protocol for plasmid DNA extraction, was originally developed to prepare plasmid DNA from 1 to 3 ml miniprep Escherichia coli cultures . Direct extraction of plasmid DNA is achieved by a two-phase solution which is separated by centrifugation in the presence of the INSTA-PREP gel barrier material . This method has been successfully tested on various environmental Salmonella strains, although it was not suitable for Pseudomonas aeruginosa and enterococci strains . The INSTA-MINI-PREP method is a new alternative procedure to screen plasmid contents of Salmonella and E . coli strains rapidly and easily.

Int Microbiol, 1998 Sep, 1(3), 197 - 204
Molecular mechanisms of Salmonella invasion: the type III secretion system of the pathogenicity island 1; Suarez M et al.; Salmonella spp . are facultative intracellular pathogens which are able to enter into non-phagocytic cells as an essential step in their pathogenic life cycle . The majority of the molecular determinants involved in this entry process are encoded in a pathogenicity island located at the centisome 63 of the bacterial chromosome, and belong to a specialized protein secretion system termed "type III" or "contact-dependent" . This secretion system is used by Salmonella spp . and several other bacterial pathogens to translocate bacterial effector proteins into the eukaryotic cell . Thus, a bidirectional biochemical cross-talk with the host cell is initiated, which leads to several responses such as membrane ruffling, bacterial internalization and the activation of various transcription factors.

Mutat Res, 2000 Dec 20, 457(1-2), 41 - 55
Mutagenicity in lung of big Blue((R)) mice and induction of tandem-base substitutions in Salmonella by the air pollutant peroxyacetyl nitrate (PAN): predicted formation of intrastrand cross-links; DeMarini DM et al.; Peroxyacetyl nitrate (PAN) is a ubiquitous air pollutant formed from NO(2) reacting with acetoxy radicals generated from ambient aldehydes in the presence of sunlight and ozone . It contributes to eye irritation associated with photochemical smog and is present in most urban air . PAN was generated in a chamber containing open petri dishes of Salmonella TA100 (gas-phase exposure) . After subtraction of the background mutation spectrum, the spectrum of PAN-induced mutants selected at 3.1-fold above the background mutant yield was 59% GC-->TA, 29% GC-->AT, 2% GC-->CG, and 10% multiple mutations - primarily GG-->TT tandem-base substitutions . Using computational molecular modeling methods, a mechanism was developed for producing this unusual tandem-base substitution . The mechanism depends on the protonation of PAN near the polyanionic DNA to release NO(2)(+) resulting in intrastrand dimer formation . Insertion of AA opposite the dimerized GG would account for the tandem GG-->TT transversions . Nose-only exposure of Big Blue((R)) mice to PAN at 78ppm (near the MTD) was mutagenic at the lacI gene in the lung (mutant frequency +/-S.E . of 6.16+/-0.58/10(5) for controls versus 8.24+/-0.30/10(5) for PAN, P=0.016) . No tandem-base mutations were detected among the 40 lacI mutants sequenced . Dosimetry with 3H-PAN showed that 24h after exposure, 3.9% of the radiolabel was in the nasal tissue, and only 0.3% was in the lung . However, based on the molecular modeling considerations, the labeled portion of the molecule would not have been expected to have been bound covalently to DNA . Our results indicate that PAN is weakly mutagenic in the lungs of mice and in Salmonella and that PAN produces a unique signature mutation (a tandem GG-->TT transversion) in Salmonella that is likely due to a GG intrastrand cross-link . Thus, PAN may pose a mutagenic and possible carcinogenic risk to humans, especially at the high concentrations at which it is present in some urban environments.

Mutat Res, 2000 Dec 20, 457(1-2), 15 - 30
Induction of chromosome aberrations in vitro by phenolphthalein: mechanistic studies; Armstrong MJ et al.; Phenolphthalein induces tumors in rodents but because it is negative in assays for mutation in Salmonella and in mammalian cells, for DNA adducts and for DNA strand breaks, its primary mechanism does not seem to be DNA damage . Chromosome aberration (Ab) induction by phenolphthalein in vitro is associated with marked cytotoxicity . At very high doses, phenolphthalein induces weak increases in micronuclei (MN) in mouse bone marrow; a larger response is seen with chronic treatment . All this suggests genotoxicity is a secondary effect that may not occur at lower doses . In heterozygous TSG-p53((R)) mice, phenolphthalein induces lymphomas and also MN, many with kinetochores (K), implying chromosome loss . Induction of aneuploidy would be compatible with the loss of the normal p53 gene seen in the lymphomas.Here we address some of the postulated mechanisms of genotoxicity in vitro, including metabolic activation, inhibition of thymidylate synthetase, cytotoxicity, oxidative stress, DNA damage and aneuploidy . We show clearly that phenolphthalein does not require metabolic activation by S9 to induce Abs . Inhibition of thymidylate synthetase is an unlikely mechanism, since thymidine did not prevent Ab induction by phenolphthalein . Phenolphthalein dramatically inhibited DNA synthesis, in common with many non-DNA reactive chemicals that induce Abs at cytotoxic doses . Phenolphthalein strongly enhances levels of intracellular oxygen radicals (ROS) . The radical scavenger DMSO suppresses phenolphthalein-induced toxicity and Abs whereas H(2)O(2) potentiates them, suggesting a role for peroxidative activation . Phenolphthalein did not produce DNA strand breaks in rat hepatocytes or DNA adducts in Chinese hamster ovary (CHO) cells . All the evidence points to an indirect mechanism for Abs that is unlikely to operate at low doses of phenolphthalein . We also found that phenolphthalein induces mitotic abnormalities and MN with kinetochores in vitro . These are also enhanced by H(2)O(2) and suppressed by DMSO . Our findings suggest that induction of Abs in vitro is a high-dose effect in oxidatively stressed cells and may thus have a threshold . There may be more than one mechanism operating in vitro and in vivo, possibly indirect genotoxicity at high doses and also chromosome loss, both of which would likely have a threshold.

Microbiol Mol Biol Rev, 2000 Dec, 64(4), 694 - 708
Coupling of flagellar gene expression to flagellar assembly in Salmonella enterica serovar typhimurium and Escherichia coli; Chilcott GS et al.; How do organisms assess the degree of completion of a large structure, especially an extracellular structure such as a flagellum? Bacteria can do this . Mutants that lack key components needed early in assembly fail to express proteins that would normally be added at later assembly stages . In some cases, the regulatory circuitry is able to sense completion of structures beyond the cell surface, such as completion of the external hook structure . In Salmonella and Escherichia coli, regulation occurs at both transcriptional and posttranscriptional levels . One transcriptional regulatory mechanism involves a regulatory protein, FlgM, that escapes from the cell (and thus can no longer act) through a complete flagellum and is held inside when the structure has not reached a later stage of completion . FlgM prevents late flagellar gene transcription by binding the flagellum-specific transcription factor sigma(28) . FlgM is itself regulated in response to the assembly of an incomplete flagellum known as the hook-basal body intermediate structure . Upon completion of the hook-basal body structure, FlgM is exported through this structure out of the cell . Inhibition of sigma(28)-dependent transcription is relieved, and genes required for the later assembly stages are expressed, allowing completion of the flagellar organelle . Distinct posttranscriptional regulatory mechanisms occur in response to assembly of the flagellar type III secretion apparatus and of ring structures in the peptidoglycan and lipopolysaccharide layers . The entire flagellar regulatory pathway is regulated in response to environmental cues . Cell cycle control and flagellar development are codependent . We discuss how all these levels of regulation ensure efficient assembly of the flagellum in response to environmental stimuli.

MedGenMed . 1999 Jun 10;:E16.
Primary Psoas Abscess Due to Salmonella typhi; Baccaro FG; Typhoid fever is a febrile illness caused by Salmonella typhi . The usual symptoms include fever, malaise, and compromise of the gut such as diarrhea and abdominal pain . Occasionally, an extraintestinal involvement can be seen and it may be accompanied by severe complications like bowel perforation or massive hemorrhage . The general manifestations are always present in the extraintestinal compromise, and can be preponderant . However, nonintestinal involvement without the general symptoms that this case reports is so rare that no related records can be found in the MEDLINE database.

J Dairy Sci, 2000 Nov, 83(11), 2441 - 7
A cross-sectional study on the prevalence of Listeria monocytogenes and Salmonella in New York dairy herds; Hassan L et al.; As part of our long-term objective of assessing risk for Listeria monocytogenes and Salmonella spp . in dairy herds, we carried out a cross-sectional study to determine the prevalence of the two organisms . The study population consisted of a sample of dairy herds enrolled in the Quality Milk Promotion Services at Cornell during the period of April 1998 to March 1999 . The sample was stratified by geographical region to assure representation . Four hundred and four dairy farms were enrolled in the study . In-line milk filters were collected from each farm for bacteriological examination of L . monocytogenes and Salmonella spp . Four hypothesized risk factors were evaluated for their association with the likelihood of the presence of each of the two organisms using logistic regression analysis . Listeria monocytogenes was isolated from 51 (12.6%) of the milk filters . We found region-specific differences in the rate of farms with positive milk filters for this pathogen . Salmonella spp . were isolated from 6 (1.5%) milk filters . One isolate was confirmed as Salmonella enterica Serotype Typhimurium DT 104 . There was no significant association between any of the hypothetical risk factors and the likelihood of Salmonella spp . isolation . Our study demonstrated that both L . monocytogenes and Salmonella spp . were prevalent in milk filters in New York dairy herds and that Salmonella was isolated at a significantly lower rate then L . monocytogenes.

J Antimicrob Chemother, 2000 Dec, 46(6), 965 - 71
Antibiotic resistance in salmonellae isolated from humans and animals in France: comparative data from 1994 and 1997; Breuil J et al.; Among 25526 recorded isolates of salmonellae, 5086 isolated from humans and 20440 from animals in 1994 and 1997 in France, the antibiotic resistance phenotype was determined for all human and 5336 animal isolates . In Salmonella enterica serovar typhimurium, one of the two most frequently isolated serovars from humans as well as animals, resistance to ampicillin was observed in 61% of both human and animal isolates in 1994 and in 73% of human and 53% of animal isolates in 1997 . During these periods, resistance to co-amoxiclav was between 45% and 66% for both types of isolate . Resistance to ampicillin was associated with resistance to streptomycin, spectinomycin, sulphonamide, tetracycline and chloramphenicol in over 70% of isolates . Resistance to ampicillin as well as co-amoxiclav never exceeded 7% in Salmonella enteritidis . While Salmonella hadar was practically absent among the human isolates in 1994, this serovar was the third most frequent in 1997, and at that time 92% were resistant to nalidixic acid . Among the animal S . hadar isolates, the prevalence of resistance to nalidixic acid increased from 3% in 1994 to 72% in 1997 . None of these isolates manifested high-level resistance to ofloxacin . The levels of resistance to aminoglycosides (< or =3%) and trimethoprim-suphamethoxazole (< or =14%) remained practically unchanged in all three serovars . The resistance markers of 463 ampicillin-resistant S . typhimurium isolated in 1997 were determined . Among the 24 phenotypes observed, six multiresistance phenotypes, representing 82% of these isolates (as compared with 80% in 1994), were associated with the PSE-1 gene typically found in the lysotype DT104 of this serovar.

Microbiology, 2000 Dec, 146 Pt 12, 3227 - 35
Invasiveness in chickens, stress resistance and RpoS status of wild-type Salmonella enterica subsp . enterica serovar typhimurium definitive type 104 and serovar enteritidis phage type 4 strains; Jorgensen F et al.; The heat and acid resistance and the ability to survive airdrying on commonly used kitchen surfaces were assessed for clinical and environmental strains of Salmonella enterica subsp . enterica serovar Typhimurium, definitive type (DT) 104 . Three out of thirty-eight strains of DT 104 were found to be more sensitive in stationary phase to the stresses examined than the other strains . This compares to a previous study by the authors which showed that seven out of forty serovar Enteritidis phage type (PT) 4 strains were more sensitive . RpoS activity was examined indirectly in selected strains of DT 104 and PT 4 . In those with normal stress resistance a 100-fold induction of an RpoS-dependent spvR/A:'::luxCDABE fusion was observed upon entry into stationary phase . The sensitive strains examined showed either no induction or a reduced level of spvR/A:'::luxCDABE expression . The rpoS gene was sequenced from these strains and three were found to harbour mutations including one deletion, one base-pair substitution resulting in a nonsense codon, and one insertion causing a frameshift resulting in an early stop codon . Strains with negligible or reduced spvR/A:'::luxCDABE expression had low stress resistance . All strains of DT 104 could be recovered from liver and spleen tissues of infected hens 14 d post-infection, but one with no induction of spvR/A:'::luxCDABE expression was significantly less likely to be recovered from chicken reproductive tissues, liver or spleen than the majority of other strains, including one with reduced spvR/A:'::luxCDABE expression . This work has demonstrated that clinical and environmental strains of DT 104 and PT 4 not infrequently harbour mutations in the rpoS allele . It is possible that the rpoS mutations may have occurred during the initial isolation of the strains . The ability of a strain to cause infection, however, also depends on factors such as host susceptibility and dose.

J Clin Microbiol, 2000 Dec, 38(12), 4676 - 8
Salmonella enterica serovar virchow with CTX-M-like beta-lactamase in Spain; Simarro E et al.; Four Salmonella enterica serovar Virchow strains resistant to broad-spectrum cephalosporins were isolated from patients with gastroenteritis in 1997 and 1998 in Murcia and Barcelona, Spain . The isolates expressed a beta-lactamase with a pI of about 8 and a positive PCR when specific primers for CTX-M-9 were used . These results suggest the presence of a CTX-M-9 beta-lactamase in these strains.

J Clin Microbiol, 2000 Dec, 38(12), 4633 - 6
Antimicrobial resistance of Salmonella isolates from swine; Gebreyes WA et al.; We examined the antimicrobial resistance of 1,257 isolates of 30 serovars of Salmonella enterica subsp . enterica isolated from swine . Serovars Typhimurium and Typhimurium var . Copenhagen were widespread and were frequently multidrug resistant, with distinct resistance to ampicillin, kanamycin, streptomycin, sulfamethoxazole, and tetracycline and to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline, respectively.

J Clin Microbiol, 2000 Dec, 38(12), 4459 - 62
Diarrhea in children under 5 years of age from Ifakara, Tanzania: a case-control study; Gascon J et al.; A matched case-control study was conducted in the Maternal and Child Health Clinic (MCH) in Ifakara, Tanzania, during the rainy season in order to elucidate the risk factors for and etiology of diarrheal diseases in children under 5 years of age . Cases (103) and controls (206) were matched for sex and age group . Precoded questionnaires with demographic details, clinical history, and physical signs were completed . Stools samples were collected for bacterial, parasitological, and viral studies . A high number of siblings (odds ratio {OR}, 0.86; P = 0.027), the number of siblings surviving (OR, 0.82; P = 0.007), the birth order (OR, 0.85; P = 0.018) and the distance from the house to the water source (OR, 0.33; P = 0.011) were associated with the risk of diarrhea . There were high rates of enteropathogen isolates in stool samples from children without diarrhea (52.23%) . Shigella species were the only enteropathogen statistically related with diarrhea (OR, 2.90; P < 0.029) . Enterotoxigenic, enteropathogenic, and enteroaggregative strains of Escherichia coli were not related with diarrhea, and neither were Giardia lamblia or Salmonella species.

J Clin Microbiol, 2000 Dec, 38(12), 4425 - 9
Prevalence of diarrheagenic Escherichia coli in finns with or without diarrhea during a round-the-world trip; Keskimaki M et al.; The incidence of diarrhea and the prevalence of bacterial enteropathogens, viruses, and parasites in feces of subjects with and without diarrhea were evaluated in 204 Finns traveling round the world (from Finland to China, Malaysia, Australia, Fiji, Chile, and Brazil and back to Finland) . Special emphasis was placed on the finding of diarrheagenic Escherichia coli (enterotoxigenic, enteropathogenic, Shiga toxin-producing, and enteroaggregative strains) by PCR from growth on primary culture plates . From the PCR-positive samples, corresponding strains were isolated, confirmed as E . coli, and O serotyped . Of all the subjects, 37% experienced a total of 90 episodes of diarrhea . No adenoviruses or rotaviruses were detected, and findings of parasites were insignificant . In contrast, enteropathogenic bacteria were present in 62% of the 65 diarrheal and in 33% of the 127 nondiarrheal samples (P < 0.001); diarrheagenic E . coli strains were found in 35 and 26% of these, respectively (not statistically significant) . As a single pathogen, E . coli was found in 20 and 24% of samples (not significant) . Of all diarrheagenic E . coli strains, enteropathogenic strains were the most commonly found independently of the clinical picture of the subjects, whereas Salmonella enterica as a single pathogen was the most common non-E . coli organism found in diarrheal samples . Multiple bacterial pathogens were found 10 times more commonly in diarrheal than in nondiarrheal samples (20 versus 2%; P < 0.001).

Appl Environ Microbiol, 2000 Dec, 66(12), 5472 - 6
Simultaneous detection of Salmonella strains and Escherichia coli O157:H7 with fluorogenic PCR and single-enrichment-broth culture; Sharma VK et al.; A multiplex fluorogenic PCR assay for simultaneous detection of pathogenic Salmonella strains and Escherichia coli O157:H7 was developed and evaluated for use in detecting very low levels of these pathogens in meat and feces . Two sets of primers were used to amplify a junctional segment of virulence genes sipB and sipC of Salmonella and an intragenic segment of gene eae of E . coli O157:H7 . Fluorogenic reporter probes were included in the PCR assay for automated and specific detection of amplified products . The assay could detect <10 CFU of Salmonella enterica serovar Typhimurium or E . coli O157:H7 per g of meat or feces artificially inoculated with these pathogens and cultured for 6 to 18 h in a single enrichment broth . Detection of amplification products could be completed in </=4 h after enrichment.

Appl Environ Microbiol, 2000 Dec, 66(12), 5406 - 9
Long-term shifts in patterns of antibiotic resistance in enteric bacteria; Houndt T et al.; Several mechanisms are responsible for the ability of microorganisms to tolerate antibiotics, and the incidence of resistance to these compounds within bacterial species has increased since the commercial use of antibiotics became widespread . To establish the extent of and changes in the diversity of antibiotic resistance patterns in natural populations, we determined the MICs of five antibiotics for collections of enteric bacteria isolated from diverse hosts and geographic locations and during periods before and after commercial application of antibiotics began . All of the pre-antibiotic era strains were susceptible to high levels of these antibiotics, whereas 20% of strains from contemporary populations of Escherichia coli and Salmonella enterica displayed high-level resistance to at least one of the antibiotics . In addition to the increase in the frequency of high-level resistance, background levels, conferred by genes providing nonspecific low-level resistance to multiple antibiotics, were significantly higher among contemporary strains . Changes in the incidence and levels of antibiotic resistance are not confined to particular segments of the bacterial population and reflect responses to the increased exposure of bacteria to antimicrobial compounds over the past several decades.

Appl Environ Microbiol, 2000 Dec, 66(12), 5273 - 81
Suitability of PCR fingerprinting, infrequent-restriction-site PCR, and pulsed-field gel electrophoresis, combined with computerized gel analysis, in library typing of Salmonella enterica serovar enteritidis; Garaizar J et al.; Strains of Salmonella enterica (n = 212) of different serovars and phage types were used to establish a library typing computerized system for serovar Enteritidis on the basis of PCR fingerprinting, infrequent-restriction-site PCR (IRS-PCR), or pulsed-field gel electrophoresis (PFGE) . The rate of PCR fingerprinting interassay and intercenter reproducibility was low and was only increased when DNA samples were extracted at the same time and amplified with the same reaction mixtures . Reproducibility of IRS-PCR technique reached 100%, but discrimination was low (D = 0.52) . The PFGE procedure showed an intercenter reproducibility value of 93.3% . The high reproducibility of PFGE combined with the previously determined high discrimination directed its use for library typing . The use of PFGE with enzymes XbaI, BlnI, and SpeI for library typing of serovar Enteritidis was assessed with GelCompar 4.0 software . Three computer libraries of PFGE DNA profiles were constructed, and their ability to recognize new DNA profiles was analyzed . The results obtained pointed out that the combination of PFGE with computerized analysis could be suitable in long-term epidemiological comparison and surveillance of Salmonella serovar Enteritidis, specially if the prevalence of genetic events that could be responsible for changes in PFGE profiles in this serovar was low.

Appl Environ Microbiol, 2000 Dec, 66(12), 5248 - 52
PCR detection of Salmonella enterica serotype Montevideo in and on raw tomatoes using primers derived from hilA; Guo X et al.; Salmonellae have been some of the most frequently reported etiological agents in fresh-produce-associated outbreaks of human infections in recent years . PCR assays using four innovative pairs of primers derived from hilA and sirA, positive regulators of Salmonella invasive genes, were developed to identify Salmonella enterica serotype Montevideo on and in tomatoes . Based on examination of 83 Salmonella strains and 22 non-Salmonella strains, we concluded that a pair of hilA primers detects Salmonella specifically . The detection limits of the PCR assay were 10(1) and 10(0) CFU/ml after enrichment at 37 degrees C for 6 and 9 h, respectively . When the assay was validated by detecting S . enterica serotype Montevideo in and on artificially inoculated tomatoes, 10(2) and 10(1) CFU/g were detected, respectively, after enrichment for 6 h at 37 degrees C . Our results suggest that the hilA-based PCR assay is sensitive and specific, and can be used for rapid detection of Salmonellae in or on fresh produce.

Eur J Cancer, 2000 Dec, 36(18), 2397 - 402
Antitumour effects of genetically engineered Salmonella in combination with radiation; Platt J et al.; The antitumour efficacy of lipid A mutant Salmonella was evaluated alone and in combination with X-rays in mice bearing B16F10 or Cloudman S91 melanomas . Each treatment alone slowed tumour growth and prolonged survival, and the combined treatments produced supra-additive antitumour effects . That is, in dose-response studies with single doses of Salmonella and increasing doses of radiation, the two agents together caused suppression of tumour growth that was greater than that calculated for additivity . The results suggest that the combination of these genetically engineered Salmonella with radiotherapy could be a new and beneficial treatment for solid tumours.

Biol Neonate, 2000 Nov, 78(4), 308 - 14
Sublethal endotoxemia promotes pulmonary cytokine-induced neutrophil chemoattractant expression and neutrophil recruitment but not overt lung injury in neonatal rats; Tillema MS et al.; Gram-negative sepsis and septic shock remain major causes of morbidity and mortality in the newborn . Respiratory failure is a common feature in neonatal sepsis regardless of the presence or absence of associated pneumonia . In adult animal models, cytokine-induced neutrophil chemoattractant (CINC) is a potent chemoattractant for neutrophils and believed to play a role in endotoxin-induced lung injury . We examined this in a neonatal model . Ten-day-old Sprague-Dawley rats were injected with Salmonella enteritidis endotoxin (ETX) 0.03 mg/kg i.p . and sacrificed at baseline, 30 min, 1, 2, 4, 8 and 16 h post-ETX . Blood was collected by cardiac puncture . After bronchoalveolar lavage, lung tissue was collected and evaluated for neutrophil (polymorphonuclear leukocyte) recruitment by myeloperoxidase assay (MPO) . Lung CINC expression was measured by Northern blot and ELISA . Peripheral blood leukocytosis was noted at 1 h (p < 0.001) with counts below baseline at 2 and 4 h . Differential counts revealed neutrophilia at 8 h (p < 0.001) . MPO revealed pulmonary PMN recruitment peaking at 1 h (p < 0.05) and CINC RNA and protein expression peaked slightly later at 2 h (p < 0 . 001) . No overt lung injury was noted by bronchoalveolar lavage cell counts or by histology . Therefore, pulmonary CINC expression and neutrophil recruitment follows LPS exposure in neonatal rats . This may represent priming of the lung tissue and a secondary event may be necessary for injury to occur.

Poult Sci, 2000 Nov, 79(11), 1571 - 4
Salmonella penetration of egg shells and proliferation in broiler hatching eggs--a review; Cox NA et al.; The presence of salmonellae in fertile broiler hatching eggs has been clearly identified as a critical control point in the salmonellae contamination of broiler chickens . This paper reviews the published research studies on a) the penetration and proliferation of salmonellae in hatching eggs, b) the consequences of this contamination on the contamination of the final product, and c) the egg's defenses against invading salmonellae . A better understanding of the material in this review paper will assist poultry researchers and the poultry industry in continuing to make progress in reducing and eliminating salmonellae from fertile hatching eggs, hatcheries, and breeder flocks.

Poult Sci, 2000 Nov, 79(11), 1557 - 61
Characterization of the contribution of water activity and moisture content to the population distribution of Salmonella spp . in commercial poultry houses; Hayes JR et al.; Because Salmonella spp . can be spread from the production environment to the consumer, strategies are required to control Salmonella . One such intervention involves control of the distribution of the organism in poultry litter . In this regard, we have attempted to determine whether Salmonella spp . are uniformly distributed throughout the litter of commercial poultry houses, or if they are unevenly localized to "hot spots" associated with high surface litter water activity (Aw) and high total moisture levels . Of the 86 houses sampled, 48 (55.8%) were positive for Salmonella spp . using a combination of the drag swab and targeted litter culturing methods . Data are presented that show that elevated Aw and percentage moisture content values representative of targeted litter samples or whole-house moisture status are not statistically predictive of Salmonella contamination, using either drag swab or targeted litter culture results as indicators of contamination . This study suggests that favorable environmental conditions for the growth of Salmonella are unequally dispersed in poultry houses . Because there is not equivalent distribution of salmonellae in the surface litter, the drag swab technique is apparently necessary to adequately survey for Salmonella spp . contamination . The findings further suggest that the development of a methodology to detect areas within houses that possess risk factors favorable for Salmonella growth must also include elevated Aw and percentage moisture content levels . This capability may enable a grower to detect and intervene in these targeted areas with neutralizing procedures, agents, or other substances to provide significant reduction of Salmonella or other poultry-associated food-borne pathogens.

Int J Antimicrob Agents, 2000 Nov, 16(3), 347 - 8
Ciprofloxacin versus chloramphenicol in the treatment of salmonella infection; Liberti A et al.; Strains of Salmonella typhi resistant to chloramphenicol and ampicillin have been isolated in several countries . This study compares treatment of Salmonella infection using ciprofloxacin (500 mg twice daily) for 10 days with chloramphenicol (50 mg/kg per day divided into four doses) for 14 days . The pathogen eradication rates for patients receiving ciprofloxacin was 18/20 (90%), compared with 25/28 (89%) for those who received chloramphenicol . Signs and symptoms in patients receiving chloramphenicol lasted longer and sometimes twice as long as patients treated with ciprofloxacin . In this study, ciprofloxacin was superior to cloramphenicol in the treatment of S . typhi infection and also had fewer side-effects and the convenience of a twice-a-day dosing

Int J Antimicrob Agents, 2000 Nov, 16(3), 249 - 51
Decrease of antibiotic resistance in Salmonella typhi isolated from patients attending hospitals of Dhaka City over a 3 year period; Zahurul Haque Asna SM et al.; Salmonella typhi is an important cause of enteric fever in Bangladesh . Resistance to commonly used antibiotics like cotrimoxazole and ampicillin has led to the introduction of third generation cephalosporins and fluoroquinolones for the treatment of enteric fever . Prescription patterns for enteric fevers and for other infections have been changing and so we looked at the antibiotic resistance of S . typhi isolated from patients in and around Dhaka City from 1996-1998 . The study showed a gradual change in resistance to ampicillin and cotrimoxazole among S . typhi in our area . The rate of resistance to cotrimoxazole, ampicillin and chloramphenicol decreased from 59.6 to 5.6% in S . typhi over a 3 year period . The extensive use of third generation cephalosporins and fluoroquinolones, in place of conventional antibiotics, has probably influenced the change in resistance pattern in S . typhi.

Int J Antimicrob Agents, 2000 Nov, 16(3), 211 - 7
Natural antibiotic susceptibility of Salmonella enterica strains; Stock I et al.; The susceptibility of 100 Salmonella enterica strains belonging to S . enterica subsp . enterica (n=90) and S . enterica subsp . arizonae (n=10) was examined to 71 antibiotics . Within S . enterica subsp . enterica, strains of different serovars (typhimurium (n=17), enteritidis (n=17), dublin (n=10), typhi (n=16), paratyphi A (n=6), others (n=24)) were studied . MICs were determined using a microdilution procedure and apart from fosfomycin there were no significant differences in susceptibility between the subspecies and serovars of S . enterica . All salmonellae were sensitive or intermediately resistant to tetracyclines, aminoglycosides, most beta-lactam antibiotics, quinolones, co-trimoxazole group antibiotics, chloramphenicol, nitrofurantoin and azithromycin . S . enterica strains were intrinsically resistant to benzylpenicillin, oxacillin, most macrolides, rifampicin, lincosamides, streptogramins, glycopeptides and fusidic acid . Apart from some slight differences in antibiotic susceptibility between strains of S . enterica subsp . enterica and S . enterica subsp . arizonae, only the susceptibility to fosfomycin varied among the taxa studied . Whereas 'enteric' salmonellae including S . enterica subsp . arizonae were sensitive to fosfomycin, 'typhoid' salmonellae were intrinsically resistant . A database of the antibiotic susceptibility of S . enterica was set up . It may be of use to validate antibiotic susceptibility test results of these bacteria.

J Biomol Struct Dyn, 2000 Oct, 18(2), 261 - 71
Homology model of surface antigen OmpC from Salmonella typhi and its functional implications; Arockiasamy A et al.; Homology based 3D structural model of the immunodominant major surface antigen OmpC from Salmonella typhi, an obligatory human pathogen, was built to understand the possible unique conformational features of its antigenic loops with respect to other immunologically cross reacting porins . The homology model was built based on the known crystal structures of the E . coli porins OmpF and PhoE . Structure based sequence alignment helped to define the structurally conserved regions (SCRs) . The SCR regions of OmpC were modelled using the coordinates of corresponding regions from reference proteins . Surface exposed variable regions were modelled based on the sequence similarity and loop search in PDB . Structural refinement based on symmetry restrained energy minimization resulted in an agreeable model for the trimer of OmpC . The resulting model was compared with other porin structures, having b-barrel fold with 16 transmembrane beta-strands, and found that the variable regions are unique in terms of sequence and structure . A ranking of the loops taking into account the antigenic index, the sequence variability, the surface accessibility in the context of the trimer, and the structural variability suggests that loop 4 (151-172), loop 5 (194-218) and loop 6 (237-264) are the best ranked B-cell epitopes . The model provides possible explanations for the functional and unique immunological properties associated with the surface exposed regions and outlines the implications for structure based experimental design.

J Exp Med, 2000 Nov 20, 192(10), 1415 - 24
Severe lung lesions caused by Salmonella are prevented by inhibition of the contact system; Persson K et al.; Vascular damage induced by trauma, inflammation, or infection results in an alteration of the endothelium from a nonactivated to a procoagulant, vasoconstrictive, and proinflammatory state, and can lead to life-threatening complications . Here we report that activation of the contact system by Salmonella leads to massive infiltration of red blood cells and fibrin deposition in the lungs of infected rats . These pulmonary lesions were prevented when the infected animals were treated with H-D-Pro-Phe-Arg-chloromethylketone, an inhibitor of coagulation factor XII and plasma kallikrein, suggesting that inhibition of contact system activation could be used therapeutically in severe infectious disease.

Vet Clin North Am Food Anim Pract, 2000 Nov, 16(3), 559 - 97
The concentration of swine production . Effects on swine health, productivity, human health, and the environment; Donham KJ; The concern about environmental issues centering around CAFOs is appropriate . The veterinary profession can be an important force in meeting these challenges by broadening its scope of knowledge and practice into the broader environmental field . Although animal agriculture's contribution to environmental concerns is the focus of this article, it is only one of several sectors that contributes to environmental degradation . Crop production, as well as livestock production industries, contribute to pollution . Manufacturing industries, municipalities, private individuals, our consumptive lifestyles, and agriculture all contribute to the degradation of our environment . One must keep in mind the huge importance of our agricultural industry and not single it out to the detriment of its progress . We have an abundance of high-quality foods at the lowest cost to the individual of any industrialized nation . We export over 40 billion dollars in agricultural products yearly . Agriculture sustains our rural economies and provides opportunities for over 2 million private enterprises scattered across the country; however, there is a goal that we have a sustainable agriculture . A big part of that depends on development and enhancement of an agriculture that does not pollute, that sustains its farm operators and workers, and that does not make the area residents ill or degrade their quality of life; however, the current situation is not promising . Much remains to be learned about the actual acute and long-term health consequences of animal agricultural pollution . Many health concerns are speculative, even though based on sound facts . We know that many surface waters have excess N and P that leads to eutrophication and possibly enhanced growth of undesirable organisms such as Pfiesteria piscicida . We know that other animal pathogens, such as cryptosporidia, have caused large community outbreaks . There are other potential pathogens, such as Salmonella sp, for which we do not know the hazard . We know that our soils may become excessively laden with P, Cu, and Zn, which retard plant growth and create toxic conditions for grazing animals . There are concerns about air pollution . Odors have negative sensory and physical health consequences . H2S and dust may cause toxic effects on neighbors . NH3 vaporizing from manure sources may be carried with precipitation to cause eutrophication in lakes or altered ecosystems in natural areas . CH4 escaping from degrading manure contributes to greenhouse gases . Workers in confined livestock structures have high risk for a variety of chronic respiratory conditions . They also are at risk for acute poisoning from H2S in operations where liquid manure is stored in confined spaces . There have been numerous health complaints in recent years from community neighbors of large-scale livestock operations . One study showed adverse altered mood states, and another showed evidence of respiratory illness similar to what workers experience . Although it has not been possible to objectively measure conditions and know toxic levels of substances causing these illnesses, there are so-called extratoxic mechanisms, such as inherent aversion to putrefactive odors and exacerbation of preexisting conditions that lower the tolerance threshold . Environmental concerns regarding livestock production are not new . In the early and mid-1970s, there were many conferences and publications regarding odors and water contamination from livestock operations . Although most of what is known in this area has been known for 20 years, relatively little effective efforts have been made to correct the concerns . In fact, trends over this past decade have increased the concerns . This past decade has seen a tremendous acceleration in the concentration and consolidation of agriculture, capping a slow trend over the past 50 years toward larger, fewer, and more-specialized farms . This trend has gone against the old saying that "dilution is the solution to pollution.

Trop Gastroenterol, 2000 Jul-Sep, 21(3), 121 - 3
Role of molecular typing in an outbreak of Salmonella paratyphi A; Chandel DS et al.; During the post monsoon season of 1996 an outbreak of human Salmonellosis caused by Salmonella serovar-paratyphi A occurred in New Delhi and had continued for over 2 months . A total of 36 clinically diagnosed enteric-fever cases were reported during this outbreak . The isolates were compared following their characterisation by biotyping, antibiogram-analysis, plasmid-profiling and IS200 probing, to study the relatedness in order to delineate a common source . The study included representative strains from both outbreak (15) and sporadic (7) cases for comparative analysis . Biotyping, antibiogram, whole cell protein-analysis and plasmid-profiling could not discriminate sporadic cases from outbreak strains, suggesting that a single clone/type (PT-1) may be prevalent in our region . In contrast, molecular-typing using IS200-probing revealed 2 clonally related strains circulating during the outbreak, as compared to the unrelated sporadic strains which exhibited considerable genetic diversity . Molecular analysis by IS200-probing, helped to assign an index case which provided a history of later outbreaks, since paratyphi A was repeatedly cultured in later outbreaks also . The study also suggests that genetic rearrangements can occur during the emergence of outbreaks . It reaffirmed the usefulness of IS200-probing in epidemiological investigations of Salmonella enterica serovars.

Infect Immun, 2000 Dec, 68(12), 7202 - 8
Localization of dysfunctional tight junctions in Salmonella enterica serovar typhimurium-infected epithelial layers; Jepson MA et al.; Infection of polarized MDCK epithelial layers by Salmonella enterica serovar Typhimurium is accompanied by increased tight junction permeability and by contraction of perijunctional actinomyosin . We localized dysfunctional tight junctions in serovar Typhimurium-infected MDCK layers by imaging apical-basolateral intramembrane diffusion of fluorescent lipid and found that loss of the apical-basolateral diffusion barrier (tight junction fence function) was most marked in areas of prominent perijunctional contraction . The protein kinase inhibitor staurosporine prevented perijunctional contraction but did not reverse the effects of serovar Typhimurium on tight junction barrier function . Hence, perijunctional contraction is not required for Salmonella-induced tight junction dysfunction and this epithelial response to infection may be multifactorial.

Infect Immun, 2000 Dec, 68(12), 7126 - 31
mig-14 is a horizontally acquired, host-induced gene required for salmonella enterica lethal infection in the murine model of typhoid fever; Valdivia RH et al.; We have characterized a host-induced virulence gene, mig-14, that is required for fatal infection in the mouse model of enteric fever . mig-14 is present in all Salmonella enterica subspecies I serovars and maps to a region of the chromosome that appears to have been acquired by horizontal transmission . A mig-14 mutant replicated in host tissues early after infection but was later cleared from the spleens and livers of infected animals . Bacterial clearance by the host occurred concomitantly with an increase in gamma interferon levels and recruitment of macrophages, but few neutrophils, to the infection foci . We hypothesize that the mig-14 gene product may repress immune system functions by interfering with normal cytokine expression in response to bacterial infections.

Infect Immun, 2000 Dec, 68(12), 7122 - 5
Development of an in vivo model for study of intestinal invasion by Salmonella enterica in chickens; Aabo S et al.; An in vivo loop test model for the investigation of the invasiveness of Salmonella enterica in chickens was developed . Ten jejunal loops were made in 10- to 12-week-old Lohman Brown chickens under isofluoran anaesthesia . Salmonella at 5.0 x 10(7) CFU was inoculated into each loop and left for 2 h, followed by a 1-h incubation with gentamicin in order to kill noninvading bacteria . After euthanasia, Salmonella invasiveness was measured as tissue-associated counts relative to a reference strain . The ability of Salmonella invasion was 1 log(10) CFU higher per 42-mm(2) mucosal tissue in the anterior than in the posterior part of jejunum . A statistically significant (P<0.001) sixfold difference in invasiveness was observed between a wild-type S . enterica serotype Typhimurium strain and the corresponding invH mutant . The model was shown to be able to show small differences in invasive capability and allows for comparison of strains tested in different animals, provided that the same reference strain is present in all animals.

Infect Immun, 2000 Dec, 68(12), 6790 - 7
Regulation of Salmonella enterica serovar typhimurium invasion genes by csrA; Altier C et al.; Penetration of intestinal epithelial cells by Salmonella enterica serovar Typhimurium requires the expression of invasion genes, found in Salmonella pathogenicity island 1 (SPI1), that encode components of a type III secretion apparatus . These genes are controlled in a complex manner by regulators within SPI1, including HilA and InvF, and those outside SPI1, such as the two-component regulators PhoP/PhoQ and BarA/SirA . We report here that epithelial cell invasion requires the serovar Typhimurium homologue of Escherichia coli csrA, which encodes a regulator that alters the stability of specific mRNA targets . A deletion mutant of csrA was unable to efficiently invade cultured epithelial cells and showed reduced expression of four tested SPI1 genes, hilA, invF, sipC, and prgH . Overexpression of csrA from an induced araBAD promoter also negatively affected the expression of these genes, indicating that CsrA can act as both a positive and a negative regulator of SPI1 genes and suggesting that the bacterium must tightly control the level or activity of CsrA to achieve maximal invasion . We found that CsrA affected hilA, a regulator of the other three genes we tested, probably by controlling one or more genetic elements that regulate hilA . We also found that both the loss and the overexpression of csrA reduced the expression of two regulators of hilA, hilC and hilD, suggesting that csrA exerts its control of hilA through one or both of these regulators . We further found, however, that CsrA could affect the expression of both invF and sipC independent of its effects on hilA . One additional striking phenotype of the csrA mutant, not observed in a comparable E . coli mutant, was its slow growth . Phenotypic revertants that had normal growth rates, while maintaining the csrA mutation, were common . These suppressed strains, however, did not recover the ability to invade cultured cells, indicating that the csrA-mediated loss of invasion cannot be attributed simply to poor growth and that the growth and invasion deficits of the csrA mutant arise from effects of CsrA on different targets.

Infect Immun, 2000 Dec, 68(12), 6763 - 9
Salmonella enterica serovar typhimurium invasion is repressed in the presence of bile; Prouty AM et al.; As enteric pathogens, the salmonellae have developed systems by which they can sense and adapt appropriately to deleterious intestinal components that include bile . Previously, growth in the presence of bile was shown to repress the transcription of prgH, a locus encoding components of the Salmonella pathogenicity island I (SPI-1) type III secretion system (TTSS) necessary for eukaryotic cell invasion . This result suggested an existing interaction between salmonellae, bile, and eukaryotic cell invasion . Transcription assays demonstrated that invasion gene regulators (e.g., sirC and invF) are repressed by bile . However, bile does not interact with any of the invasion regulators directly but exerts its effect at or upstream of the two-component system at the apex of the invasion cascade, SirA-BarA . As suggested by the repression of invasion gene transcription in the presence of bile, Western blot analysis demonstrated that proteins secreted by the SPI-1 TTSS were markedly reduced in the presence of bile . Furthermore, Salmonella enterica serovar Typhimurium grown in the presence of bile was able to invade epithelial cells at only 4% of the level of serovar Typhimurium grown without bile . From these data, we propose a model whereby serovar Typhimurium uses bile as an environmental signal to repress its invasive capacity in the lumen of the intestine, but upon mucous layer penetration and association with intestinal epithelial cells, where the apparent bile concentration would be reduced, the system would become derepressed and invasion would be initiated.

Gene Ther, 2000 Oct, 7(20), 1725 - 30
In vivo correction of genetic defects of monocyte/macrophages using attenuated Salmonella as oral vectors for targeted gene delivery; Paglia P et al.; Macrophages are normal targets for Salmonella during natural infections, and it has been demonstrated that attenuated bacteria can deliver nucleic acid vaccine constructs . Therefore, we assessed if attenuated Salmonella can be used for the in vivo delivery of transgenes to their natural cellular target, in an attempt to correct genetic defects associated with monocytes/macrophages . This system would offer the distinct advantage of achieving a specific targeting of defective cells in a non-invasive form . Using a reporter gene, we demonstrated that attenuated Salmonella could be used as an effective in vitro delivery system to transfer genetic material into nondividing cells like murine macrophages . In vivo, the oral administration of attenuated Salmonella allows targeted delivery of transgenes to macrophages and subsequently expression of transgenes at a systemic level . IFNgamma-deficient mice (GKO) were thus selected as a model for the in vivo validation of the Salmonella-based delivery approach . Attenuated Salmonella, used as the carrier for a eukaryotic expression vector encoding the murine IFNgamma gene, was able to restore the production of this cytokine in GKO macrophages . Their oral administration to IFNgamma-deficient mice also re-established, in these immunocompromised animals, the natural resistance to bacterial infections . These results demonstrate, for the first time, that attenuated Salmonella can be successfully used in vivo as a DNA delivery system for the correction of a genetic defect associated with monocyte/macrophages.

Res Microbiol, 2000 Oct, 151(8), 639 - 54
Identification of Escherichia coli O-serogroups by restriction of the amplified O-antigen gene cluster (rfb-RFLP); Coimbra RS et al.; The precise serotyping of clinical Escherichia coli isolates is a crucial step for diagnostic and epidemiological purposes . Epidemiological knowledge associated with serotyping is so important that no alternative method may be considered if it does not correlate with serotyping . Unfortunately, E . coli are difficult to serotype . Genes specifically involved in O-antigen synthesis are clustered in E . coli, Shigella and Salmonella . Published oligonucleotide sequences complementary to JUMPstart and the gnd gene (the conserved flanking sequences upstream and downstream of O-antigen gene clusters, respectively) were used to amplify the O-antigen gene cluster of representative strains of 148 E . coli O-serogroups . A unique amplified fragment was observed for each serogroup (size ranging from 1.7 to 20 kbp) . Clearly identifiable and reproducible O-patterns were obtained for the great majority of O-serogroups after MboII digestion of amplified products . The number of bands composing each pattern varied from five to 25 . A database was built with the patterns obtained . A total of 147 O-patterns were obtained . Thirteen O-serogroups were subdivided into different O-patterns . However, each of 13 other O-patterns was shared by two or more O-serogroups . 0-serogroups of clinical isolates were deduced accurately from O-patterns in all cases, even for some rough or nonagglutinating isolates . The restriction method (rfb-RFLP) may prove to be better than serotyping since 100% of strains are typable, which is not the case with serotyping.

Mutat Res, 2000 Nov 20, 471(1-2), 135 - 43
Development of a Salmonella tester strain sensitive to promutagenic N-nitrosamines: expression of recombinant CYP2A6 and human NADPH-cytochrome P450 reductase in S . typhimurium YG7108; Kushida H et al.; We developed a new Salmonella tester strain highly sensitive to promutagenic N-nitrosamines by introducing a plasmid carrying human cytochrome P450 2A6 (CYP2A6) and NADPH-cytochrome P450 reductase (OR) cDNA into the ada- and ogt-deficient strain YG7108 . The YG7108 2A6/OR cells expressed high levels of CYP2A6 (77+/-8nmol/l) and OR (470+/-20 micromol cytochrome c reduced/min/l) . The expressed CYP2A6 efficiently catalyzed coumarin 7-hydroxylation . N-Nitrosodiethylamine (NDEA), N-nitrosomethylphenylamine (NMPhA), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were mutagenic in the new strain in the absence of any exogenous activation system . The concentrations of promutagen that caused a two-fold increase in revertants were 7.1, 0.14, and 1.4 microM for NDEA, NMPhA, and NNK, respectively . YG7108 2A6/OR cells showed about 10- and 100-fold higher sensitivity to NDEA and NNK, respectively, than parental YG7108 cells assayed in the presence of rat liver S9 (final concentration, 21% (v/v)) . Parental YG7108 cells did not detect NMPhA mutagenicity even in the presence of rat liver S9 . We believe that this is the first demonstration that CYP2A6 is responsible for the metabolic activation of NMPhA . The established tester strain may be useful to predict human activation of N-nitrosamine promutagens.

J Food Prot, 2000 Nov, 63(11), 1475 - 82
Comparison of aqueous chemical treatments to eliminate Salmonella on alfalfa seeds; Weissinger WR et al.; Several outbreaks of salmonellosis associated with alfalfa sprouts have been documented in the United States since 1995 . This study was undertaken to evaluate various chemical treatments for their effectiveness in killing Salmonella on alfalfa seeds . Immersing inoculated seeds in solutions containing 20,000 ppm free chlorine (Ca{OCl}2), 5% Na3PO4, 8% H2O2, 1% Ca(OH)2, 1% calcinated calcium, 5% lactic acid, or 5% citric acid for 10 min resulted in reductions of 2.0 to 3.2 log10 CFU/ g . Treatment with 1,060 ppm Tsunami or Vortex, 1,200 ppm acidified NaClO2, or 5% acetic acid were less effective in reducing Salmonella populations . With the exceptions of 8% H2O2, 1% Ca(OH)2, and 1% calcinated calcium that reduced populations by 3.2, 2.8, and 2.9 log10 CFU/g, respectively, none of treatments reduced the number of Salmonella by more than 2.2 log10 CFU/g without significantly reducing the seed germination percentage . Treatment with 5% acetic, lactic, or citric acids substantially reduced the ability of seeds to germinate . Treatment with 1% Ca(OH)2 in combination with 1% Tween 80, a surfactant, enhanced inactivation by 1.3 log10 CFU/g compared to treatment with 1% Ca(OH)2 alone . Presoaking seeds in water, 0.1% EDTA, 1% Tween 80, or 1% Tween 80 plus 0.1% EDTA for 30 min before treatment with water, 2,000 ppm NaOCl, or 2% lactic acid had a minimal effect on reducing populations of Salmonella . Results indicate that, although several chemical treatments cause reductions in Salmonella populations of up to 3.2 log10 CFU/g initially on alfalfa seeds when analyzed by direct plating, no treatment eliminated the pathogen, as evidenced by detection in enriched samples.

Antisense Nucleic Acid Drug Dev, 2000 Oct, 10(5), 391 - 9
Bacterial systems for the delivery of eukaryotic antigen expression vectors; Dietrich G et al.; Attenuated bacterial strains allow the administration of recombinant vaccines via the mucosal surfaces . Whereas attenuated bacteria are generally engineered to express heterologous antigens, a novel approach employs intracellular bacteria for the delivery of eukaryotic antigen expression vectors (so-called DNA vaccines) . This strategy allows a direct delivery of DNA to professional antigen-presenting cells (APC), such as macrophages and dendritic cells (DC), through bacterial infection . The bacteria used for DNA vaccine delivery either enter the host cell cytosol after phagocytosis by the APC, for example, Shigella and Listeria, or they remain in the phagosomal compartment, such as Salmonella . Both intracellular localizations of the bacterial carriers seem to be suitable for successful delivery of DNA vaccine vectors.

Eur J Epidemiol, 2000, 16(7), 613 - 8
An outbreak of Salmonella Hadar associated with roast rabbit in a restaurant; Bisbini P et al.; In August 1997, an outbreak of gastroenteritis from Salmonella Hadar phage type 2 occurred among customers of a restaurant in Rimini (Emilia-Romagna region, Italy) . Twenty-nine people who had eaten food prepared in the restaurant on 2 or 3 August had symptoms of acute gastroenteritis . The infection was culture-confirmed in 24 cases and the stool specimens of four healthy people were positive for Salmonella Hadar . Twelve people had to be hospitalized and a 3-year old girl died . The case-control study identified roast rabbit as the likely vehicle of infection (OR: 6.00; CI 95%: 1.65-22.83) . The microbiological investigation carried out on food taken from the restaurant confirmed high levels of Salmonella Hadar in a sample of roast rabbit . Since the rabbit was well cooked, the food contamination likely occurred after cooking . Poor hygienic conditions found in the restaurant, together with inappropriate food-handling practices and inadequate storage temperatures may have contributed to spread to other foods and the severity of the outbreak.

Emerg Infect Dis, 2000 Nov-Dec, 6(6), 649 - 51
Genotypic analysis of multidrug-resistant Salmonella enterica Serovar typhi, Kenya; Kariuki S et al.; We report the emergence in Kenya during 1997-1999 of typhoid fever due to Salmonella enterica serovar Typhi resistant to ampicillin, tetracycline, chloramphenicol, streptomycin, and cotrimoxazole . Genotyping by pulsed-field gel electrophoresis of XbaI-digested chromosomal DNA yielded a single cluster . The multidrug-resistant S . Typhi were related to earlier drug- susceptible isolates but were unrelated to multidrug-resistant isolates from Asia.

Trop Doct, 2000 Oct, 30(4), 195 - 7
Multidrug-resistant typhoid fever; Kabra SK et al.; One hundred children (consecutive) with positive blood culture for Salmonella typhi were studied for clinical profile and complications.The common clinical features were fever (100%), vomiting (58%), abdominal pain (48%), cough (22%) and loose stools (14%) and the Widal test was positive in 75% patients . Eighty per cent of the salmonella isolates were resistant to amoxycillin, chloramphenicol and co-trimoxazole drugs, but all were sensitive to ciprofloxacin and ceftriaxone . Forty patients developed complications: encephalopathy (18), melaena (12), haematemesis (10), epistaxis (4), hepatitis (4), acalculous cholecystitis (4), bowel perforation (3) and nephritis (2) . Complications were more frequent in children with multidrug-resistant typhoid.The final antibiotic required to render the children afebrile included ciprofloxacin (80), ceftriaxone, amoxycillin (4), chloramphenicol (4), amoxycillin and gentamicin (4), amoxycillin with chloramphenicol (2), and furazolidone (2).The defervesence time was least with ceftriaxone and greatest with amoxycillin . All the affected children made a complete recovery.

Enferm Infecc Microbiol Clin, 2000 Jun-Jul, 18(6), 257 - 61
{Food poisoning outbreak due to the consumption of spaghetti a la carbonara caused by Salmonella enteritidis}; Godoy P et al.; INTRODUCTION: This paper reports a clinico-epidemiological and microbiological investigation conducted into an outbreak of gastrointestinal infection due to Salmonella enteritidis, where the most likely food vehicle was spaghetti a la carbonara . METHODS: An historic cohort study was conducted out among persons exposed to menus at a school canteen . Data were gathered on age, sex, foods consumed and clinical symptoms . School premises and menus were inspected, food samples obtained (spaghetti and meat balls), and stool samples taken from 30 affected subjects and 8 food handlers . Isolated strains were studied using pulsed-field electrophoresis . Attack rates were computed, and the odds ratio adjusted for the remaining foodstuffs (ORa) used to calculate the independent contribution made by the respective foods to risk of infection . RESULTS: Study coverage was 75.7% (140/185) . The overall attack rate was 72.1% (101/140), with 12.9% of those affected requiring hospitalisation . The multivariate analysis showed that, while the spaghetti maintained its association (ORa = 8.4; 95% CI 1.4-51.8), the meat balls registered a reduction in risk (ORa = 1.8; 95% CI 0.4-7.5) . S . enteritidis was isolated in stool cultures from 28 affected subjects, and in 2 blood and 6 stool cultures from food handlers (5 of whom were classed as cases) . Moreover, S . enteritidis was also isolated in the food samples . On pulsed-field electrophoresis, the strains registered the same electrophoresis pattern . CONCLUSIONS: This outbreak serves to underscore the gravity of Salmonella spp . food poisoning, the danger of using inadequately cooked eggs, and the importance of interviewing food handlers to ensure proper classification (i.e., as patients or carriers) . Existing recommendations as to the use of pasteurised egg products ought to be extended in scope.

J Emerg Med, 2000 Nov, 19(4), 317 - 21
Emergency department presentations of typhoid fever; Hoffner RJ et al.; Typhoid fever, a systemic infectious disease caused by Salmonella typhi, is classically characterized by fever, paradoxical bradycardia, abdominal pain, and a rose colored rash . This was a retrospective review of 21 confirmed cases over a 5-year period . Mean age was 32.6 years (range 2-60 years), and Mexico (7/21) and El Salvador (3/21) represented the most common countries of origin . Recent travel to an endemic area was noted in 14 patients . The most common complaints were fever (15/21), headache (10/21), abdominal pain (9/21), and diarrhea (6/21) . Average duration of symptoms before presentation to the Emergency Department (ED) was 7.9 days . High fever associated with bradycardia was noted in 12 patients . Leukopenia was present in 7 patients . Blood culture was the most sensitive confirmatory test while the Widal test was positive in 7 out of 11 cases . Fever of unknown origin (12/21), followed by presumed typhoid fever (3/21) were the most common ED diagnoses . It is important to recognize that patients with typhoid fever may present to EDs in the US and this disease should be included in the differential diagnosis of febrile patients from Latin America or those with a history of recent travel to endemic countries.

J Bacteriol, 2000 Dec, 182(23), 6638 - 44
InvB is a type III secretion chaperone specific for SspA; Bronstein PA et al.; A wide variety of gram-negative bacteria utilize a specialized apparatus called the type III secretion system (TTSS) to translocate virulence factors directly into the cytoplasm of eukaryotic cells . These translocated effectors contribute to the pathogen's ability to infect and replicate within plant and animal hosts . The amino terminus of effector proteins contains sequences that are necessary and sufficient for both secretion and translocation by TTSS . Portions of these sequences contain binding sites for type III chaperones, which facilitate efficient secretion and translocation of specific effectors through TTSS . In this study, we have utilized the yeast two-hybrid assay to identify protein-protein interactions between effector and chaperone proteins encoded within Salmonella pathogenicity island 1 (SPI-1) . Several interactions were identified including a novel interaction between the effector protein, SspA (SipA), and a putative chaperone, InvB . InvB was demonstrated to bind to the amino terminus of SspA in the bacterial cytoplasm . Furthermore, InvB acts as a type III chaperone for the efficient secretion and translocation of SspA by SPI-1 . InvB also permitted translocation of SspA through the SPI-2 TTSS, indicating that it is an important regulator in the recognition of SspA as a target of TTSS . Finally, it was determined that InvB does not alter the transcription of sspA but that its absence results in reduced SspA protein levels in Salmonella enterica serovar Typhimurium.

Clin Infect Dis, 2000 Nov, 31(5), 1134 - 8 Epub 2000 Nov 06.
Azithromycin versus ceftriaxone for the treatment of uncomplicated typhoid fever in children; Frenck RW Jr et al.; A total of 108 children aged 4-17 years were randomized to receive 7 days of azithromycin (10 mg/kg/day; maximum, 500 mg/day) or ceftriaxone (75 mg/kg/day; maximum, 2.5 g/day), to assess the efficacy of the agents for the treatment of uncomplicated typhoid fever . Salmonella typhi was isolated from the initial cultures of blood samples from 64 patients . A total of 31 (91%) of the 34 patients treated with azithromycin and 29 (97%) of the 30 patients treated with ceftriaxone were cured (P>.05) . All 64 isolates were susceptible to azithromycin and ceftriaxone . Of the patients treated with ceftriaxone, 4 subsequently had relapse of their infection . No serious side effects occurred in any study subject . Oral azithromycin administered once daily appears to be effective for the treatment of uncomplicated typhoid fever in children . If these results are confirmed, the agent could be a convenient alternative for the treatment of typhoid fever, especially in individuals in developing countries where medical resources are scarce.

J Med Microbiol, 2000 Nov, 49(11), 1011 - 21
Invasiveness of Salmonella serotypes Typhimurium and Enteritidis of human gastro-enteritic origin for rabbit ileum: role of LPS, plasmids and host factors; Martin GD et al.; An organ culture system involving explants of distal rabbit ileum was used to study the roles of lipopolysaccharide (LPS) and plasmids in primary invasiveness for enterocytes in situ of strains of Salmonella serotypes Typhimurium and Enteritidis . Long-chain LPS per se does not confer invasiveness on Typhimurium, as known avirulent, hypo-invasive strains express smooth LPS . However, the invasiveness of a naturally occurring rough isogenic derivative of Salmonella serotype Enteritidis PT 4 was about half that of its wild-type parent . Therefore, smooth LPS appears to play a secondary role in maximising invasiveness . No evidence was found to correlate primary invasiveness for gut of 18 strains of Typhimurium with plasmid profiles in general or with the 60-MDa serovar-specific virulence plasmid in particular . Evidence is presented that strongly suggests a seasonal variability in susceptibility of rabbit gut to invasion by Typhimurium . Although no explanation is given for this summer insusceptibility, the data indicate the importance of the physiological status of the host in relation to susceptibility to invasion by Salmonella.

Acta Paediatr, 2000 Sep, 89(9), 1087 - 92
Anti-endotoxin antibodies in human milk: correlation with infection of the newborn; Feist N et al.; A longitudinal study was performed to investigate the content of human colostrum and milk of antibodies against endotoxins of Escherichia coli, Pseudomonas aeruginosa and Salmonella minnesota during the first 6 mo of lactation . The influence of the gestational age of the newborn and the prevalence of a systemic infection in the child on maternal antibody production were observed . Colostrum of mothers of term infants who had shown signs of systemic infection contained higher antibody concentrations compared to colostrum of mothers of healthy newborns . After the first week post partum, no difference in the milk's antibody content could be observed between these two groups . Antibody titres rose from 2 wk to 6 mo post partum (p < 0.001) . Milk of mothers of preterm infants with signs of systemic infection contained higher antibody titres than milk of mothers of preterm infants without infection throughout the observation period . This difference reached statistical significance 3 wk after delivery (p < 0.05) . The corrected endotoxin antibody levels against all tested antigens in milk of mothers of preterm infants with infection 6 mo post partum were 6+/-3.5 times as high as 2 wk post partum . CONCLUSIONS: Breast milk contains anti-endotoxin antibodies . The particularly high levels of antiendotoxin antibodies in cases of neonatal infection may present a special maternal protection for premature infants.

Lett Appl Microbiol, 2000 Nov, 31(5), 374 - 7
Salmonella enteritidis and aerobic mesophiles in inoculated poultry sausages manufactured with high-pressure processing; Yuste J et al.; Salmonella enteritidis-inoculated poultry sausages were pressurized at 500 MPa by combining different times (10 and 30 min) and temperatures (50, 60 and 70 degrees C) or heat treated with the same temperature-time combinations and a standard cooking (75 degrees C for 30 min) . Counts of Salm . enteritidis and mesophilic bacteria were determined . Most pressure treatments generated statistically higher reductions than the corresponding heat treatments alone . Lethalities of about 7.5 and 6.5 log cfu g(-1) for Salm . enteritidis and mesophiles, respectively, were found in pressurized sausages . There was no significant difference in counts between pressurization at 60 degrees C for 30 min or at 70 degrees C and the standard cooking . High-pressure processing is a suitable alternative method in poultry sausage manufacture.

Lett Appl Microbiol, 2000 Oct, 31(4), 328 - 31
Evaluation of two assays, MSRV and RV, for the isolation of Salmonella spp . from wastewater samples and broiler chickens; Zdragas A et al.; The Rappaport Vassiliadis (RV) and the Modified Semi-solid Rappaport Vassiliadis (MSRV) methods were evaluated in 130 municipal wastewater samples and 30 flocks of broilers . Analysis of the results showed that 71 Salmonella serotypes were isolated in wastewater samples . The positivity of the MSRV method was 33% and of the RV method, 45% . The sensitivity was 95% and 83% with the MSRV and RV, respectively . The concordance between the two methods was 89% (k = 0785) . One hundred serotypes were isolated from broiler internal organs and 50 from intestinal samples . For internal organs, the positivity of MSRV was 56% and of RV, 45% . For intestinal samples, the respective percentages were 28 and 22 . For internal organs, the sensitivity was 100% with MSRV and 81% with RV, whereas for intestinal samples, the sensitivity was 100% with MSRV and 80% with RV . The specificity was 100% in all cases . The concordance between the two methods was 89% (k = 0790) for internal organs and 94% (k = 0851) for intestinal samples.

Lett Appl Microbiol, 2000 Oct, 31(4), 279 - 83
The detection of Salmonella using a combined immunomagnetic separation and ELISA end-detection procedure; Mansfield LP et al.; The aim of this study was to develop a rapid immunoassay to detect Salmonella bacteria . Skimmed milk powder (SMP) in buffered peptone water was inoculated with six Salmonella strains (Salm . typhimurium, Salm . virchow, Salm . enteritidis, Salm . give, Salm . ealing and Salm . arizonae) at three inoculum levels (about 2-200 cfu 25 g(-1) SMP) and incubated (37 degrees C) overnight . Heat-treated salmonella cells were immobilized on paramagnetic particles and detected within 3 h using the Salmonella genus-specific monoclonal antibody M105 in a microtitre plate based assay . The rapid Salmonella detection method combining immunomagnetic separation and ELISA had a total isolation and detection time of less than 24 h, which is significantly shorter than the conventional techniques requiring 72-96 h . The technique had a sensitivity limit of 10(5)-10(6) cfu ml(-1).

J Immunol, 2000 Nov 15, 165(10), 5780 - 7
Toll-like receptor 4, but not toll-like receptor 2, is a signaling receptor for Escherichia and Salmonella lipopolysaccharides; Tapping RI et al.; Two members of the mammalian Toll-like receptor (TLR) family, TLR2 and TLR4, have been implicated as receptors mediating cellular activation in response to bacterial LPS . Through the use of mAbs raised against human TLR2 and TLR4, we have conducted studies in human cell lines and whole blood to ascertain the relative contribution of these receptors to LPS induced cytokine release . We show that the contribution of TLR2 and TLR4 to LPS-induced cellular activation correlates with the relative expression levels of these two TLRs in a given cell type . In addition, we have found that significant differences in cell stimulatory activity exist between various smooth and rough LPS types that cannot be ascribed to known LPS structural features . These results suggest that impurities in the LPS may be responsible for some of the activity and this would be in agreement with recently published results of others . Upon repurification, none of the commercial LPS preparations activate cells through TLR2, but continue to stimulate cells with comparable activity through TLR4 . Our results confirm recent findings that TLR4, but not TLR2, mediates cellular activation in response to LPS derived from both Escherichia coli and Salmonella minnesota . Additionally, we show that TLR4 is the predominant signaling receptor for LPS in human whole blood.

Regul Toxicol Pharmacol, 2000 Oct, 32(2), 219 - 25
The proportions of mutagens among chemicals in commerce; Zeiger E et al.; It has been estimated that there are approximately 80,000 chemicals in commerce . Thus, it is not possible to test all these substances for mutagenicity and carcinogenicity; it is possible, however, to test or make estimates from selected subsets of these chemicals . For example, in the U.S . National Toxicology Program (NTP), 35% of the chemicals tested for mutagenicity in Salmonella were positive, as were 52% of the chemicals tested for carcinogenicity in rodents . In contrast, in the U.S . EPA Gene-Tox database, the proportions of chemicals that are Salmonella mutagens is 56% . These and other databases may be biased toward positive responses because they generally have been developed to look at specific structural or use classes of chemicals or chemicals suspected of genetic or carcinogenic activity . To address the question of the proportions of mutagens among all chemicals in commerce, a database of 100 chemicals was created from a random selection of chemicals in commerce . These chemicals were tested for mutagenicity in Salmonella and 22% were mutagenic . The mutagenicity of the 46 highest U.S . production organic chemicals was also compiled; 20% were mutagenic . These values provide a more accurate estimate of the proportions of mutagens among chemicals in commerce than can be derived from published mutagenicity databases .

J Biol Chem, 2001 Feb 23, 276(8), 5498 - 504 Epub 2000 Nov 07.
Purification and characterization of WaaP from Escherichia coli, a lipopolysaccharide kinase essential for outer membrane stability; Yethon JA et al.; In Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa, the waaP (rfaP) gene product is required for the addition of phosphate to O-4 of the first heptose residue of the lipopolysaccharide (LPS) inner core region . This phosphate substitution is particularly important to the biology of these bacteria; it has previously been shown that WaaP is necessary for resistance to hydrophobic and polycationic antimicrobials in E . coli and that it is required for virulence in invasive strains of S . enterica . WaaP function is also known to be essential for the viability of P . aeruginosa . The predicted WaaP protein shows low levels of similarity (10-15% identity) to eukaryotic protein kinases, but its kinase activity has never been tested . Here we report the purification of WaaP and the reconstitution of its enzymatic activity in vitro . The purified enzyme catalyzes the incorporation of 33P from {gamma-33P}ATP into acceptor LPS purified from a defined E . coli waaP mutant . Enzymatic activity is dependent upon the presence of Mg2+ and is maximal from pH 8.0 to 9.0 . The apparent Km (determined at saturating concentrations of the second substrate) is 0.13 mm for ATP and 76 microm for LPS . These data are the first proof that WaaP is indeed an LPS kinase . Further, site-directed mutagenesis of a predicted catalytic residue suggests that WaaP shares a common mechanism of action with eukaryotic protein kinases.

FEMS Immunol Med Microbiol, 2000 Nov, 29(3), 221 - 5
Application of randomly amplified polymorphic DNA (RAPD) analysis for typing avian Salmonella enterica subsp . enterica; Chansiripornchai N et al.; Randomly amplified polymorphic DNA (RAPD) analysis was performed for the molecular genetic typing of 30 Salmonella enterica subsp . enterica strains isolated from chickens and ducks in Thailand . Six different primers were tested for their discriminatory ability . While some of the primers could only differentiate between the different serovars, the use of multiple primers showed that the RAPD method could also subdivide within a given serovar . The Ready-To-Go RAPD analysis beads used, resulted in reproducible and stable banding patterns . As the RAPD technique is simple, rapid and rather cheap, we suggest that it may be a valuable new tool for studying the molecular genetic epidemiology of S . enterica ssp . enterica, both inter- and intra-serovars.

Clin Diagn Lab Immunol, 2000 Nov, 7(6), 977 - 9
Rapid detection of Salmonella enterica serovar Choleraesuis in blood cultures by a dot blot enzyme-linked immunosorbent assay; Janyapoon K et al.; A dot blot enzyme-linked immunosorbent assay (ELISA) with a monoclonal antibody specific to phase1-c Salmonella was developed for the direct detection of Salmonella enterica serovar Choleraesuis in blood cultures . This system was applied to the identification of serovar Choleraesuis, and the results were compared with those obtained by a conventional biochemical method . It was revealed that all 12 samples identified to be infected with serovar Choleraesuis were positive on testing by the ELISA . In contrast, 77 samples infected with bacteria commonly isolated from the blood were not reactive by the ELISA . The calculated sensitivity and specificity of the established assay are 100%.

New Microbiol, 2000 Oct, 23(4), 367 - 82
Results from the first computerised Italian surveillance of human Salmonella isolates . The Italian SALM-NET Working Group; Scuderi G et al.; We report all the first computerised data collected in Italy for the surveillance of Salmonella isolates . Primarily, within the wide framework of the European Community Human Salmonella Surveillance Project (SALM-NET), we report data on the most commonly isolated serotypes in Italy from January 1994 to December 1996 . In addition, we report all computerised data historically collected by some Italian regions regarding the period 1980-1993 . Total data included in the Italian SALM-NET data base account for 59,336 Salmonella isolates . In the list of the most frequent isolates starting from 1989, S . Enteritidis always ranked first, followed by S . Typhimurium.

J Pediatr, 2000 Nov, 137(5), 687 - 93
Long-term follow-up and outcome of 39 patients with chronic granulomatous disease; Liese J et al.; OBJECTIVES: To evaluate the clinical long-term course in patients with chronic granulomatous disease (CGD) with respect to different CGD subtypes and currently used antimicrobial prophylactic measures . STUDY DESIGN: The records of 39 patients with CGD who were monitored during a period of 22 years were reviewed . All infections, infectious complications, and clinical outcomes were documented for a total observation period of 610 patient-years and were stratified with respect to different CGD subtypes . RESULTS: Lymphadenitis, skin abscesses, and pneumonia occurred in 87%, 72%, and 59% of the patients, respectively . In 151 microbiologic isolates Staphylococcus aureus, Aspergillus species, Candida species, Pseudomonas species, and Salmonella species were the most frequently detected microorganisms . There were 167 severe infections requiring hospitalization and intravenous antimicrobial treatment, resulting in an incidence of 3.7 severe infections per 100 patient months (SI/100 PM) . Long-term antibiotic prophylaxis significantly reduced the incidence of severe bacterial infections from 4.8 SI/100 PM to 1 . 6 SI/100 PM (P =.0035) . In contrast, fungal infections increased under antibiotic prophylaxis from a mean incidence of 0.2 SI/100 PM to 1.9 SI/100 PM (P =.04) . We found a 50% survival rate through the fourth decade of life, with a plateau after the third decade of life . Patients with a complete absence of cytochrome b(558) showed an earlier manifestation of their disease and a higher incidence of infections and had significant lower survival than patients with only diminished cytochrome b(558) or autosomal recessive CGD . CONCLUSIONS: Infections with Aspergillus species have become the major cause of infectious complications and death in patients with CGD . Prophylactic and therapeutic measures are needed to further increase life expectancy and quality for patients with CGD.

Epidemiol Infect, 2000 Aug, 125(1), 9 - 12
An outbreak of Salmonella blockley infections following smoked eel consumption in Germany; Fell G et al.; In June 1998, an increased number of persons with Salmonella blockley infection were reported from one German state . Because S . blockley is extremely uncommon in Germany, a case-control study was performed in order to find the source . A total of 13 patients met the case definition . Nine of 12 cases and 2 of 21 controls with food consumption histories reported eating smoked eel (OR 28.5; 95% CI 3.9-235.3) . The consumed eel came from four different local smokeries, but could be traced back to fish farms in Italy . This outbreak indicates that eel may be a vehicle for salmonella infection and that the smoking process may not eliminate bacterial contamination from raw fish.

Epidemiol Infect, 2000 Aug, 125(1), 1 - 8
The pandemic of Salmonella enteritidis phage type 4 reaches Utah: a complex investigation confirms the need for continuing rigorous control measures; Sobel J et al.; In 1995, Salmonella Enteritidis (SE) cases in the state of Utah increased fivefold . Isolates were identified as phage type 4 (PT4) . Risk factors and sources of infection were investigated in two case-control studies, a traceback of implicated foods, and environmental testing . Forty-three patients with sporadic infections and 86 controls were included in a case-control study of risk factors for infection . A follow-up case-control study of 25 case and 19 control restaurants patronized by case and control patients examined risks associated with restaurant practices . In the first case-control study, restaurant dining was associated with illness (P = 0.002) . In the follow-up case-control study, case restaurants were likelier to use > 2000 eggs per week (P < 0.02), to pool eggs (P < 0.05), and to use eggs from cooperative 'A' (P < 0.009) . Eggs implicated in separately investigated SE PT4 outbreaks were traced to cooperative 'A', and SE PT4 was cultured from one of the cooperative's five local farms . We conclude that SE PT4 transmitted by infected eggs from a single farm caused a fivefold increase in human infections in Utah.

Pediatr Surg Int, 2000, 16(7), 525 - 6
Large bowel obstruction: an unusual presentation of salmonella enterocolitis in infancy; Gross E et al.; An infant with a large-bowel obstruction due to Salmonella B enterocolitis is presented . The clinical and radiologic findings were suggestive of Hirschsprung's disease with total colonic aganglionosis . Due to further deterioration, an ileostomy was performed . Pathologic examination disclosed ganglia in the colon . At laparatomy, 1 month later the colon, which was almost completely obliterated, was resected and an ileorectal anastomosis carried out . The patient remained a carrier of a multiple antibiotic-resistant group B Salmonella strain, and 2 months later died as a result of severe gastroenteritis.

Acta Microbiol Immunol Hung, 2000, 47(4), 445 - 56
Rapid combined assay for Salmonella detection in food samples; Gado I et al.; A rapid method was developed to detect salmonellae in food samples . The method gave a possibility to obtain results after 28 h 30 min . The preenrichment in buffered peptone water lasted for 6 h, the enrichment in Rappaport-Vassiliadis medium was applied for 18 h followed by PCR with INVA1-INVA2 primer pair, adapting Chiu and Ou's method . This procedure was suitable to demonstrate salmonella contamination at min . 10 cfu/25 g sample . Out of 18 samples there was a good agreement between the results of the conventional and rapid methods in case of 17 samples . PCR with SPVC1-SPVC2 primer pair informing about the presence of virulence plasmid was performed in separate tubes, because decreased sensitivity was observed in case of multiplex PCR.

Appl Environ Microbiol, 2000 Nov, 66(11), 4921 - 5
Habituation of Salmonella spp . at reduced water activity and its effect on heat tolerance; Mattick KL et al.; The effect of habituation at reduced water activity (a(w)) on heat tolerance of Salmonella spp . was investigated . Stationary-phase cells were exposed to a(w) 0.95 in broths containing glucose-fructose, sodium chloride, or glycerol at 21 degrees C for up to a week prior to heat challenge at 54 degrees C . In addition, the effects of different a(w)s and heat challenge temperatures were investigated . Habituation at a(w) 0.95 resulted in increased heat tolerance at 54 degrees C with all solutes tested . The extent of the increase and the optimal habituation time depended on the solute used . Exposure to broths containing glucose-fructose (a(w) 0.95) for 12 h resulted in maximal heat tolerance, with more than a fourfold increase in D(54) values . Cells held for more than 72 h in these conditions, however, became as heat sensitive as nonhabituated populations . Habituation in the presence of sodium chloride or glycerol gave rise to less pronounced but still significant increases in heat tolerance at 54 degrees C, and a shorter incubation time was required to maximize tolerance . The increase in heat tolerance following habituation in broths containing glucose-fructose (a(w) 0.95) was RpoS independent . The presence of chloramphenicol or rifampin during habituation and inactivation did not affect the extent of heat tolerance achieved, suggesting that de novo protein synthesis was probably not necessary . These data highlight the importance of cell prehistory prior to heat inactivation and may have implications for food manufacturers using low-a(w) ingredients.

Appl Environ Microbiol, 2000 Nov, 66(11), 4842 - 8
Characterization and chromosomal mapping of antimicrobial resistance genes in Salmonella enterica serotype typhimurium; Daly M et al.; Two hundred and twenty-six Salmonella enterica serotype Typhimurium isolates were examined for the presence of integron-associated gene cassettes . All but two of the non-DT104 isolates, together with DT104 isolates, contained gene cassettes . Amplicons of 1.5 kbp each were found in two non-DT104 isolates, encoding a dhfrI gene (trimethoprim resistance) linked to an aadA gene (streptomycin and spectinomycin resistance), by site-specific recombination . DT104 isolates of resistance (R) type ACSSuT possessed the recently described 1.0- and 1.2-kbp gene cassettes . Macrorestriction analysis with XbaI and DNA probing mapped ant(3")-1a, bla(PSE-1), and dhfrI genes to large multiresistant gene clusters in a DT170a isolate and a DT193 isolate . In contrast, all DT104 isolates (R-type ACSSuT) possessed a conserved 10-kbp Xba1 DNA fragment . Our study highlights the occurrence of integrons (and antimicrobial resistance determinants) among serotype Typhimurium isolates other than DT104 . Larger and previously unrecognized multiresistance gene clusters were identified in these isolates by DNA probing.

Poult Sci, 2000 Oct, 79(10), 1408 - 13
Elimination of early Salmonella enteritidis infection after treatment with competitive-exclusion culture and enrofloxacin in experimentally infected chicks; Seo KH et al.; The effect of normal avian gut flora (NAGF) and enrofloxacin administration on the early infection of young chicks by Salmonella enteritidis (SE) was determined using day-old White Leghorn chicks . Day- old chicks were divided into two groups, untreated control and NAGF-treated, and then infected with 10(6) cfu of SE per chick by oral gavage . The untreated, infected chicks were further divided into two groups and were either left untreated or medicated with a regimen of 10 mg/kg of enrofloxacin in drinking water daily for 10 d, followed by two doses of NAGF beginning at 10 and 8 wk of age in Trial 1 and Trial 2, respectively . Liver, spleen, and cecum samples were tested for the presence of SE, and immunological responsiveness was investigated up to 12 wk of age . Compared with the untreated group, the cecal colonization of SE was significantly (P < 0.05) decreased in the NAGF-treated group in Trials 1 and 2 . No significant differences in organ infection were observed in the NAGF-treated vs . untreated birds . Although a significant effect of the combined treatment of enrofloxacin treatment and NAGF on the early infection was not shown in Trial 1, compared with enrofloxacin only or the untreated group, a significant reduction (P < 0.05) in the number of infected chickens and in the number of SE in the cecal contents was observed at 10 wk of age in Trial 2 . The enrofloxacin treatment did not increase opportunistic colonization by SE due to the use of the antibiotic in either trial . The plasma and intestinal immunological responses were not significant at the early age (up to 12 wk) of the birds . The use of enrofloxacin, followed by NAGF, could aid the elimination of SE from young chicks persistently infected at an early age . The combined treatment, compared with enrofloxacin alone, protected chickens from reinfection by 40%.

J Appl Microbiol, 2000 Oct, 89(4), 633 - 41
Molecular analysis of tetracycline resistance in Salmonella enterica subsp . enterica serovars Typhimurium, enteritidis, Dublin, Choleraesuis, Hadar and Saintpaul: construction and application of specific gene probes; Frech G et al.; A total of 65 epidemiologically unrelated tetracycline-resistant isolates of the six Salmonella enterica subsp . enterica (Salm.) serovars Dublin, Choleraesuis, Typhimurium, Enteritidis, Hadar and Saintpaul were investigated for the presence of tetracycline resistance genes . For this, specific gene probes of the tetracycline resistance genes (tet) of the hybridization classes A, B, C, D, E and G were constructed by cloning PCR-amplified internal segments of the respective tet structural genes . These gene probes were sequenced and used in hybridization experiments with plasmid DNA or endonuclease digested whole cell DNA as targets . Only tet(A) genes were detected on plasmids in all Salm . Dublin isolates as well as in single isolates of Salm . Choleraesuis and Salm . Typhimurium . Genes of the hybridization classes B, C, D and G, but also in some cases those of class A, were located in the chromosomal DNA of the corresponding Salmonella isolates . Restriction fragment length polymorphisms (RFLPs) of tet gene carrying fragments were detected in chromosomally tetracycline-resistant isolates . These RFLPs might represent valuable additional tools for the identification and characterization of tetracycline-resistant Salmonella isolates.

J Appl Microbiol, 2000 Oct, 89(4), 587 - 94
A membrane-immunofluorescent-viability staining technique for the detection of Salmonella spp . from fresh and processed meat samples; Duffy G et al.; A direct staining technique was investigated for the detection of viable Salmonella in fresh and processed meats . The technique involved overnight enrichment in BPW, extraction of Salmonella cells onto a polycarbonate membrane, followed by detection of the pathogen using anti-Salmonella monoclonal antibody coupled with an antibody linked-fluorescent stain (Texas Red) and a viability stain (Sytox Green) . The technique was applied to the detection of Salm . enteritidis inoculated into broth culture or minced beef and then subjected to a variety of stresses including freezing (- 20 degrees C), heating (2 or 4 min at 56.9 degrees C), low pH (5 or 3.5) or high salt (2 or 4%) . The correlation between traditional plate counts and the rapid count varied widely (r2 = 0.98-0.03), depending on the type and level of stress applied to the cells . The reason for the disparity in results obtained, and the potential application of the method as a diagnostic tool, are discussed.

J Bacteriol, 2000 Nov, 182(22), 6503 - 8
Transcription initiation-defective forms of sigma(54) that differ in ability To function with a heteroduplex DNA template; Kelly MT et al.; Transcription by sigma(54)-RNA polymerase holoenzyme requires an activator that catalyzes isomerization of the closed promoter complex to an open complex . We examined mutant forms of Salmonella enterica serovar Typhimurium sigma(54) that were defective in transcription initiation but retained core RNA polymerase- and promoter-binding activities . Four of the mutant proteins allowed activator-independent transcription from a heteroduplex DNA template . One of these mutant proteins, L124P V148A, had substitutions in a sequence that had not been shown previously to participate in the prevention of activator-independent transcription . The remaining mutants did not allow efficient activator-independent transcription from the heteroduplex DNA template and had substitutions within a conserved 20-amino-acid segment (Leu-179 to Leu-199), suggesting a role for this sequence in transcription initiation.

J Bacteriol, 2000 Nov, 182(22), 6472 - 81
Sequence of the genome of Salmonella bacteriophage P22; Vander Byl C et al.; The sequence of the nonredundant region of the Salmonella enterica serovar Typhimurium temperate, serotype-converting bacteriophage P22 has been completed . The genome is 41,724 bp with an overall moles percent GC content of 47.1% . Numerous examples of potential integration host factor and C1-binding sites were identified in the sequence . In addition, five potential rho-independent terminators were discovered . Sixty-five genes were identified and annotated . While many of these had been described previously, we have added several new ones, including the genes involved in serotype conversion and late control . Two of the serotype conversion gene products show considerable sequence relatedness to GtrA and -B from Shigella phages SfII, SfV, and SfX . We have cloned the serotype-converting cassette (gtrABC) and demonstrated that it results in Salmonella serovar Typhimurium LT2 cells which express antigen O1 . Many of the putative proteins show sequence relatedness to proteins from a great variety of other phages, supporting the hypothesis that this phage has evolved through the recombinational exchange of genetic information with other viruses.

J Bacteriol, 2000 Nov, 182(22), 6308 - 21
Genetics of swarming motility in Salmonella enterica serovar typhimurium: critical role for lipopolysaccharide; Toguchi A et al.; Salmonella enterica serovar Typhimurium can differentiate into hyperflagellated swarmer cells on agar of an appropriate consistency (0.5 to 0.8%), allowing efficient colonization of the growth surface . Flagella are essential for this form of motility . In order to identify genes involved in swarming, we carried out extensive transposon mutagenesis of serovar Typhimurium, screening for those that had functional flagella yet were unable to swarm . A majority of these mutants were defective in lipopolysaccharide (LPS) synthesis, a large number were defective in chemotaxis, and some had defects in putative two-component signaling components . While the latter two classes were defective in swarmer cell differentiation, representative LPS mutants were not and could be rescued for swarming by external addition of a biosurfactant . A mutation in waaG (LPS core modification) secreted copious amounts of slime and showed a precocious swarming phenotype . We suggest that the O antigen improves surface "wettability" required for swarm colony expansion, that the LPS core could play a role in slime generation, and that multiple two-component systems cooperate to promote swarmer cell differentiation . The failure to identify specific swarming signals such as amino acids, pH changes, oxygen, iron starvation, increased viscosity, flagellar rotation, or autoinducers leads us to consider a model in which the external slime is itself both the signal and the milieu for swarming motility . The model explains the cell density dependence of the swarming phenomenon.

J Endotoxin Res, 2000, 6(3), 249 - 56
The role of polar and facial amphipathic character in determining lipopolysaccharide-binding properties in synthetic cationic peptides; David SA et al.; Two series of peptides, designated K and NK were synthesized and tested for lipid A binding and neutralizing properties . K2, which has an 11-residue amphiphilic core, and a branched N-terminus bearing two branched lysinyl residues does not bind lipid A, while NK2, also with an 11-residue amphiphilic core comprised entirely of non-ionizable residues, and a similarly branched, cationic N-terminus, binds lipid A very weakly . Both peptides do not inhibit lipopolysaccharide (LPS) activity in the Limulus assay, nor do they inhibit LPS-induced TNF-alpha and NO production in J774 cells . These results are entirely unlike a homologous peptide with an exclusively hydrophobic core whose LPS-binding and neutralizing properties are very similar to that of polymyxin B {David SA, Awasthi SK, Wiese A et al . Characterization of the interactions of a polycationic, amphiphilic, terminally branched oligopeptide with lipid A and lipopolysaccharide from the deep rough mutant of Salmonella minnesota . J Endotoxin Res 1996; 3: 369-379} . These data suggest that a clear segregation of charged and apolar domains is crucial in molecules designed for purposes of LPS sequestration and that head-tail (polar) orientation of the cationic/hydrophobic regions is preferable to molecules with mixed or facial cationic/amphipathic character.

Cell, 2000 Sep 29, 103(1), 113 - 25
A signal transduction system that responds to extracellular iron; Wosten MM et al.; Iron is essential for all organisms but can be toxic in excess . Iron homeostasis is typically regulated by cytoplasmic iron binding proteins, but here we describe a signal transduction system (PmrA/PmrB) that responds to extracytoplasmic ferric iron . Iron promoted transcription of PmrA-activated genes and resistance to the antibiotic polymyxin in Salmonella . The PmrB protein bound iron via its periplasmic domain which harbors two copies of the sequence ExxE, a motif present in the Saccharomyces FTR1 iron transporter and in mammalian ferritin light chain . A pmrA mutant was hypersensitive to killing by iron but displayed wild-type resistance to a variety of oxidants, suggesting PmrA/PmrB controls a novel pathway mediating the avoidance of iron toxicity.

Ann Otol Rhinol Laryngol, 2000 Oct, 109(10 Pt 1), 958 - 64
Stimulation of adenoidal lymphocytes by Alloiococcus otitidis; Tarkkanen J et al.; Otitis media with effusion (OME) is characterized by persistent effusion in the middle ear cavity and by chronic inflammation in the middle ear mucosa . Alloiococcus otitidis, a gram-positive aerobic bacterium, has been isolated in middle ear effusion, and by means of sensitive polymerase chain reaction detection assays it has been detected in as many as 20% of middle ear aspirates of patients with OME . Because A otitidis may freely interact with leukocytes in the middle ear effusion, it may potentially modulate the inflammatory reaction in OME . To study the nature of these interactions, we applied an in vitro assay in which killed A otitidis bacteria were incubated with peripheral blood and adenoidal mononuclear cells . The expression of the proliferation-associated surface marker CD69 was then measured in B lymphocytes and in CD4+ helper and CD8+ cytotoxic-suppressor T lymphocytes by means of multicolor flow cytometry . Alloiococcus otitidis induced the expression of CD69 in both peripheral blood and adenoidal T and B cells . Among the T cells, the cytotoxic-suppressor T lymphocytes were preferentially activated . It was also tested whether A otitidis would have an effect in another cytotoxic and immunoregulatory system, namely, the induction of natural killer cell activity in peripheral blood mononuclear cells . However, the effect was minimal compared with that of Salmonella minnesota or Staphylococcus aureus . The results show that A otitidis has a unique immunostimulatory capacity in vitro that is mainly confined to CD8+ T lymphocytes.

Vet Res, 2000 Sep-Oct, 31(5), 491 - 7
Enzyme-linked immunosorbent assay with a Salmonella enteritidis antigen for differentiating infected from vaccinated poultry; Solano C et al.; The specificity and sensitivity of indirect ELISA, based on the use of four different antigenic extracts obtained from a clinical isolate of Salmonella enteritidis, were compared with those obtained with the gm-flagellin based ELISA (IDEXX) . A total of 116 serum samples from salmonellae free, naturally infected and vaccinated hens were studied . The results showed that the indirect ELISA, based on lipopolysaccharide (LPS), O-polysaccharide (PS) or membrane sediment (SD) antigens, enable the identification of a greater number of infected birds and discriminated field antibody responses from vaccinal ones better than the commercial IDEXX test . The indirect ELISA that used a O-polysaccharide rich fraction (PS) proved to be the most specific and sensitive test, suggesting that this indirect ELISA could be used to confirm IDEXX results, especially when the differentiation between vaccinated and infected poultry is required.

J AOAC Int, 2000 Sep-Oct, 83(5), 1087 - 95
Minimum detectable level of Salmonellae using a binomial-based bacterial ice nucleation detection assay (BIND); Irwin P et al.; A modified bacterial ice nucleation detection (BIND) assay was used for rapid and sensitive detection of several Salmonella species . For the BIND assay, Salmonella cells are infected with bacteriophage genetically modified to contain DNA encoding an ice nucleation protein (INP) . After infection, de novo protein synthesis occurs and INPs are incorporated into the outer membrane of the organism . After supercooling (-9.3 degrees C), only buffer solutions containing transfected salmonellae freeze, causing a phase-sensitive dye to change color . This technique, and a probability-based protocol modification, provided quantitative detection with a minimum detectable level (MDL) of 2.0 +/- 0.3 S . enteritidis cells/mL in buffer (about 3 h) . The MDLs for S . typhimurium DT104 and S . abaetetuba were 4.2 +/- 0.2 and 11.1 +/- 0.4 cells/mL, respectively . Using salmonellae-specific immunomagnetic bead separation technology in conjunction with the modified BIND protocol, we achieved an MDL of about 4.5 S . enteritidis cells/mL with an apparent capture efficiency of 56%.

Arch Latinoam Nutr, 2000 Jun, 50(2), 177 - 82
{Assessment of microbiological quality of food served in dining rooms of private enterprises}; de Curtis ML et al.; The aim of this study was to evaluate foods microbiological quality in food-service establishments . A total of 620 food samples were obtained from four establishments and analyzed for aerobic mesophilic (AM), yeasts, moulds, Staphylococcus aureus and Escherichia coli counts and the presence of Salmonella spp . Drinking water, equipment, surfaces, environment and food handlers were also sampled . E . coli was found in raw vegetables (76.2%), cooked vegetables (15.2%), beef and pork (15.9%), poultry (16.7%), fish (11.8%), desserts (27.3%), equipments (57.9%), surfaces and environment (53.6%) and in 21.9% of food handlers . Survey results were compared with the recommended maximum microbial levels . Our results demonstrate the need for the adoption of more effective hygienic measures in this kind of establishment in order to avoid any risk to consumers.

Environ Mol Mutagen, 2000, 36(3), 206 - 20
Effect of five dietary antimutagens on the genotoxicity of six mutagens in the microscreen prophage-induction assay; Cabrera G; Dietary antimutagens have been studied extensively in the last two decades, using mainly bacterial and mammalian cells . These studies have shown that certain dietary antimutagens, acting individually or as mixtures, are useful in counteracting the effects of certain mutagens and/or carcinogens to which humans are commonly exposed . However, there are some inconsistencies among publications using different bioassays . The general purpose of the research presented here was to conduct a comparative study of the antigenotoxic activity of five dietary antimutagens against six mutagens, using three rather different short-term tests: the Microscreen prophage-induction assay, the Tradescantia micronucleus test, and the Salmonella/mammalian microsome test . In this study I report the results with the Microscreen prophage-induction assay . The antimutagens selected were chlorophyllin, beta-carotene, and vitamins A, C, and E . The mutagens selected were 2-aminoanthracene, benzo{a}pyrene, 2-nitrofluorene, toxaphene, dichlorvos, and nitrofen . The results show that chlorophyllin and beta-carotene inhibited the genotoxicity of all six mutagens; vitamin E inhibited all except dichlorvos; and vitamins C and A inhibited 2-aminoanthracene, benzo{a}pyrene, 2-nitrofluorene, and nitrofen .

Biol Neonate, 2000 Oct, 78(3), 207 - 11
Effect of polyclonal anti-TNFalpha antibody on endotoxic shock in suckling rats; Bhola M et al.; The aim of this study was to evaluate the effect of anti-tumor necrosis factor alpha (TNFalpha) antibodies on the TNFalpha gene expression in a neonatal septic shock model . Ten-day-old Sprague-Dawley rats were divided into four groups and given intraperitoneal (ip) injection as follows: group 1: 0.1 ml saline; group 2: 0.1 mg/kg Salmonella enteritidis lipopolysaccharide (LPS); group 3: 1 mg/kg of anti-TNFalpha antibodies (Ab); group 4: 0.1 mg/kg of LPS and 1 mg/kg of Ab . We found that in group 2, LPS induced shock, demonstrating hypoglycemia and lactacidemia (p < 0 . 05) and death (81.8%) . Ab decreased the mortality significantly (35%) and attenuated the hypoglycemia (35 +/- 8 mg/dl in group 2 vs . 53 +/- 3 mg/dl in group 4) and lactacidemia (5.40 +/- 0.63 vs . 2.35 +/- 0.45 mmol) at 8 h in group 4 when compared to group 2 . Northern blot demonstrated a significant decrease in TNFalpha mRNA expression in group 4 as compared to group 2, at 2 h after LPS injection . We conclude that the beneficial effects of anti-TNFalpha antibodies on LPS-induced shock may be due to decreased TNFalpha gene expression .

Trends Microbiol, 2000 Oct, 8(10), 457 - 64
Bacterial interplay at intestinal mucosal surfaces: implications for vaccine development; Autenrieth IB et al.; The discovery of 'molecular syringes' in several important gastrointestinal pathogens including Escherichia coli, Salmonella, Shigella and Yersinia, together with a better understanding of M cells and the mucosal immune system, has advanced our appreciation of multistage microorganism-host cell interactions . Recent studies suggest that these molecular strategies could be adapted for the development of modular mucosal vaccines.

Int J Med Microbiol, 2000 Mar, 290(1), 7 - 13
Apoptosis as a common bacterial virulence strategy; Monack D et al.; The comparison of common strategies used by bacterial pathogens to overcome host defenses provides us with the opportunity to analyze the biology of pathogenicity, as well as point out the unique interactions between a particular pathogen and its host . Here we compare and contrast apoptosis induced by three enteric pathogens, Salmonella, Shigella, and Yersinia . We point out that all three enteric pathogens induce apoptosis in macrophages in vitro, but the proposed mechanisms are quite different . Yersinia induces apoptosis by inhibiting the translocation of the transcriptional activator, NF-kappaB, into the nucleus, which results in the suppression of TNFalpha production; whereas Salmonella- and Shigella-induced apoptosis depend on the activation of caspase-1 (casp-1) . The result of casp-1 activation is to induce apoptosis as well as to process the proinflammatory cytokines, pro-IL-1beta and pro-IL18 into their mature bioactive forms . Thus, in contrast to Yersinia, Salmonella and Shigella-induced apoptosis results in a proinflammatory cascade.

Berl Munch Tierarztl Wochenschr, 2000 Sep, 113(9), 331 - 4
{Possibilities for standardization of ELISA for detection of Salmonella antibodies in sera and meat juices of pigs}; Steinbach G et al.; Programmes for controlling salmonella infections in German piggeries are based on the meat-juice-ELISA conducted in various investigation centres by using different test-kits . A usual procedure for harmonization (standardisation) of results is the calculation of the percentage of antibody-concentration from field samples in relation to the extinctions of a set of control-sera with known antibody concentrations . Whether this system is still acceptable in case of using different test-kits seems to be questionable . In principle, difficulties arise by calculating field results from the regression curve of control-sera because the calculated percentages of antibodies do not represent the antibody concentration but, instead, the percentages of the extinctions measured, and secondly, because control-sera presently in use are directed against different salmonella serovars . In regard to the number of laboratories involved and because of a variety of test-kits used it seems to be more adequate to include only one anti-Salmonella Typhimurium standard-serum at a given antibody concentration which is to be tested repeatedly on every test-plate . Simultaneously, further controls should include another anti-Salmonella Typhimurium and one anti-Salmonella Choleraesuis serum which should provide results similar to the Danish system which is regarded as a standard . As well, a negative serum must be included in the test and a minimum difference in extinctions between this negative serum and the standard positive control-serum should be reached to prove the validity of results from the test plate.

J Biol Chem, 2001 Jan 12, 276(2), 1156 - 63
Ca2+-induced phosphoethanolamine transfer to the outer 3-deoxy-D-manno-octulosonic acid moiety of Escherichia coli lipopolysaccharide . A novel membrane enzyme dependent upon phosphatidylethanolamine; Kanipes MI et al.; Certain strains of Escherichia coli and Salmonella contain lipopolysaccharide (LPS) modified with a phosphoethanolamine (pEtN) group at position 7 of the outer 3-deoxy-d-manno-octulosonic acid (Kdo) residue . Using the heptose-deficient E . coli mutant WBB06 (Brabetz, W., Muller-Loennies, S., Holst, O., and Brade, H . (1997) Eur . J . Biochem . 247, 716-724), we now demonstrate that the critical parameter determining the presence or absence of pEtN is the concentration of CaCl(2) in the medium . As judged by mass spectrometry, half the LPS in WBB06, grown on nutrient broth with 5 mm CaCl(2), is derivatized with a pEtN group, whereas LPS from WBB06 grown without supplemental CaCl(2) is not . Membranes from E . coli WBB06 or wild-type W3110 grown on 5-50 mm CaCl(2) contain a novel pEtN transferase that uses the precursor Kdo(2)-{4'-(32)P}lipid IV(A) as an acceptor . Transferase is not present in membranes of E . coli grown with 5 mm MgCl(2), BaCl(2), or ZnCl(2) . Hydrolysis of the in vitro reaction product, pEtN-Kdo(2)-{4'-(32)P}lipid IV(A), at pH 4.5 shows that the pEtN substituent is located on the outer Kdo moiety . Membranes from an E . coli pss knockout mutant grown on 50 mm CaCl(2), which lack phosphatidylethanolamine, do not contain measurable transferase activity unless exogenous phosphatidylethanolamine is added back to the assay system . The induction of the pEtN transferase by 5-50 mm CaCl(2) suggests possible role(s) in establishing transformation competence or resisting environmental stress, and represents the first example of a regulated covalent modification of the inner core of E . coli LPS.

J Food Prot, 2000 Oct, 63(10), 1443 - 6
Improved detection of nontyphoid and typhoid Salmonellae with balanced agar formulations; Miller RG et al.; A strategically balanced medium was developed for the improved detection of nontyphoid and typhoid salmonellae . Its balanced sugar (cellobiose, lactose, mannitol, and trehalose) and protein (beef extract and polypeptone peptone) formulation provided Salmonella with a selective growth advantage over non-Salmonella enteric organisms . The formulations promoted the production and detection of H2S production levels that otherwise might be missed with traditional agar formulations . In combination, these advantages contributed to increased sensitivity without the loss of specificity . In comparative studies using 86 samples of meat products (beef, pork, and chicken), the new media, Miller-Mallinson (MM) agar and xylose lysine tergitol (Niaproof) 4 agar, possessed significantly higher sensitivity (P < 0.001) and an improved specificity over bismuth sulfite, hektoen enteric, and xylose lysine desoxycholate agars . However, these samples did not contain nontyphoid salmonellae with weak to ultraweak H2S production characteristics . Modified formulations of MM agar were generally similar to bismuth sulfite and hektoen enteric agars in the identification of four of seven globally diverse strains of Salmonella serotype Typhi . Two of these seven strains were found to produce more readily identifiable black (H2S-positive) colonies on MM agar, whereas one of the seven was not readily detected by any of the media . The improved detection of nontyphoid and typhoid salmonellae attests to the sensitivity of MM agar and to its potentially broad utility in both clinical and food quality laboratories.

J Food Prot, 2000 Oct, 63(10), 1333 - 7
Protective effect of Enterococcus faecium J96, a potential probiotic strain, on chicks infected with Salmonella Pullorum; Carina Audisio M et al.; Enterococcus faecium J96 was isolated from a healthy free-range chicken and it inhibited Salmonella Pullorum, in vitro, due to its lactic acid and bacteriocin production . In vivo assays were carried out with 30-h-old broiler chicks . The lactic acid bacteria (approximately 1 x 10(9) cells per chick) were orally administered as preventive and as therapeutic treatments . In the first case they were given to the chicks twice a day for 3 consecutive days . In the second case the lactic bacteria were administered in the same way after a 24-h challenge by Salmonella Pullorum (in both instances the salmonella dose was 1 x 10(5) cells per chick) . Cecal contents, liver, and spleens were analyzed and liver and spleen fragments were also fixed in formaldehyde (pH 7.00) in order to determine salmonella translocation . The chickens that were preventively treated with E . faecium J96 survived the Salmonella Pullorum challenge . Those that were infected on the first day and then inoculated with lactic bacteria died 4 days later . Salmonellae were isolated from their livers and spleens . From these results we may conclude that E . faecium J96 can protect newly hatched chicks from Salmonella Pullorum infection but cannot act as a good therapeutic agent.

Mol Cell Probes, 2000 Oct, 14(5), 321 - 8
Rapid and specific detection of PCR products using light-up probes; Isacsson J et al.; Newly developed light-up probes offer an attractive tool for PCR product detection . The light-up probe, which consists of a thiazole orange derivative linked to a peptide nucleic acid oligomer, hybridizes specifically to complementary nucleic acids . Upon hybridization the thiazole orange moiety interacts with the nucleic acid bases and the probe becomes brightly fluorescent . This eliminates the need to separate bound from unbound probes and reduces the risk of cross contamination during sample handling . We demonstrate here the applicability of light-up probes in two different PCR assays, one directed towards the human beta-actin gene and the other towards the invA gene of Salmonella . The probes do not interfere with the PCR reaction and can either be included in the sample mixture or added after completed amplification . The specificity of the probe is found to be excellent: a single-base mismatch in the target sequence is sufficient to prevent probe binding as indicated by the lack of fluorescence increase . Furthermore, a clear correlation is found between the intensity of gel bands and the measured probe fluorescence in solution, which suggests that the amount of PCR products can be quantified using light-up probes .

Food Chem Toxicol, 2000 Oct, 38(10), 949 - 62
A comparison of the mainstream smoke chemistry and mutagenicity of a representative sample of the US cigarette market with two Kentucky reference cigarettes (K1R4F and K1R5F); Chepiga TA et al.; The incorporation of technologies into cigarettes such as filters, filter ventilation, porous cigarette papers, expanded tobacco and reconstituted tobacco sheet has resulted in cigarettes with a wide range of "tar" yields . The objectives of this study were to characterize the US cigarette market according to "tar" category (i.e . full flavor, FF; full flavor low tar, FFLT; or ultra low tar, ULT) and to determine whether the Kentucky reference cigarettes K1R4F and K1R5F are representative of FFLT and ULT cigarettes, respectively . As a means of characterization and comparison, the mainstream smoke from a representative sample of commercially available cigarettes from each market segment and the K1R4F and K1R5F Kentucky reference cigarettes was analyzed for the presence and level of 18 selected chemical constituents . In addition, a measure of the mutagenic activity of the mainstream smoke condensate from these cigarettes was determined using an Ames Salmonella mutagenicity assay . All cigarettes were smoked according to US Federal Trade Commission (FTC) guidelines . Results indicated that, overall, mainstream smoke constituent levels are well predicted by FTC "tar" yield--constituent levels increased as "tar" delivery increased . Based on the selected analytes measured in mainstream smoke, the K1R4F reference cigarette was generally representative of the FFLT segment of the US cigarette market . The K1R5F reference cigarette was representative of the ULT segment of the US cigarette market for cigarettes with "tar" deliveries approximate to it . In terms of mutagenic activity, a direct relationship was also demonstrated on a per cigarette basis-revertants per cigarette increased with increasing "tar" delivery . There was a weak tendency (R-square = 0.12, P = 0.08) for specific activity (revertants/mg "tar") to increase with decreasing "tar" yield-lower "tar" products had a slightly higher specific activity . No significant differences (P > 0.05) were observed when the specific activities of the condensates from the K1R4F and K1R5F reference cigarettes were compared to the market segments that they were designed to represent, FFLT and ULT, respectively . Overall, these results support the use of the K1R4F and the K1R5F as acceptable reference cigarettes for comparative mutagenicity and smoke chemistry studies of cigarettes available on the US market.

Food Chem Toxicol, 2000 Nov, 38(11), 971 - 6
In vitro genotoxicity testing of ARASCO and DHASCO oils; Arterburn LM et al.; ARASCO and DHASCO oils are microbially-derived triglycerides rich in arachidonic (20:4n-6) and docosahexaenoic (22:6n-3) acids, respectively . Both oils were tested for mutagenic activity in three different in vitro mutagenesis assays . All assays were conducted with and without metabolic activation . Neither ARASCO nor DHASCO oil was mutagenic in the Ames reverse mutation assay using five different Salmonella histidine auxotroph tester strains, nor were the oils mutagenic in the mouse lymphoma TK(+/-) forward mutation assay . The oils showed no clastogenic activity in chromosomal aberration assays performed with Chinese hamster ovary cells . Based on these assays, neither ARASCO nor DHASCO oils appear to have any genotoxic potential.

Drug Metab Dispos, 2000 Nov, 28(11), 1297 - 302
Prenylflavonoids from hops inhibit the metabolic activation of the carcinogenic heterocyclic amine 2-amino-3-methylimidazo{4, 5-f}quinoline, mediated by cDNA-expressed human CYP1A2; Miranda CL et al.; The heterocyclic amine 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) is a potential human carcinogen found in cooked food that requires initial metabolic activation by cytochrome P450s, primarily CYP1A2 . The present study was conducted to examine whether recombinant human CYP1A2 expressed in insect cells mediates the metabolic activation of IQ and whether prenylflavonoids found in hops and beer would modulate the CYP1A2-mediated activation of IQ . The cDNA-expressed human CYP1A2 was found to strongly activate IQ as measured by the Ames Salmonella assay and by the covalent binding of IQ metabolites to calf thymus DNA and protein . Inhibition studies showed that the prenylchalcone xanthohumol and the prenylflavanones 8-prenylnaringenin and isoxanthohumol strongly inhibited the mutagenic activation of IQ mediated by cDNA-expressed human CYP1A2 in the Ames Salmonella assay . The three prenylflavonoids also markedly inhibited the human CYP1A2-mediated binding of IQ to metabolites that bind to DNA . The inhibition of the metabolic activation of IQ was paralleled by the inhibition of acetanilide 4-hydroxylase activity of human CYP1A2 . Thus, xanthohumol, isoxanthohumol, and prenylflavanones 8-prenylnaringenin are potent inhibitors of the metabolic activation of IQ and may have the potential to act as chemopreventive agents against cancer induced by heterocyclic amines activated by CYP1A2.

Res Microbiol, 2000 Sep, 151(7), 575 - 82
Salmonella flagellin fused with a linear epitope of colonization factor antigen I (CFA/I) can prime antibody responses against homologous and heterologous fimbriae of enterotoxigenic Escherichia coli; das Gracas Luna M et al.; In this work, a 15-amino-acid-long peptide derived from the enterotoxigenic Escherichia coli CFA/I fimbria (11VDPVIDLLQADGNAL25) was genetically fused to the Salmonella flagellin and used to prime and boost serum antibody responses (IgG) against homologous (CFA/I) and heterologous (CS1) colonization factors (CFs) in BALB/c mice . Antibodies raised against the hybrid flagellin (Fla II) cross-reacted with CFA/I, CS1, CS2, and PCFO166 but not with CS4 . Parenteral administration of Fla II primed antibody responses against both CFA/I and CS1 but boosted IgG responses only against CFA/I . These findings confirm that linear epitopes derived from the CFA/I fimbria can prime antibody responses against homologous and heterologous CFs and indicate that Salmonella flagellin represents a potential carrier for the development of broad-range peptide-based anti-colonization ETEC vaccines.

Antimicrob Agents Chemother, 2000 Nov, 44(11), 3118 - 21
Evidence for an efflux pump mediating multiple antibiotic resistance in Salmonella enterica serovar Typhimurium; Piddock LJ et al.; The mechanism of multiple antibiotic resistance in six isolates of Salmonella enterica serovar Typhimurium recovered from a patient treated with ciprofloxacin was studied to investigate the role of efflux in the resistance phenotype . Compared to the patient's pretherapy isolate (L3), five of six isolates accumulated less ciprofloxacin, three of six isolates accumulated less chloramphenicol, and all six accumulated less tetracycline . The accumulation of one or more antibiotics was increased by carbonyl cyanide m-chlorophenylhydrazone to concentrations similar to those accumulated by L3 for all isolates except one, in which accumulation of all three agents remained approximately half that of L3 . All isolates had the published wild-type sequences of marO and marR . No increased expression of marA, tolC, or soxS was observed by Northern blotting; however, three isolates showed increased expression of acrB, which was confirmed by quantitative competitive reverse transcription-PCR . However, there were no mutations within acrR or the promoter region of acrAB in any of the isolates.

Infect Immun, 2000 Nov, 68(11), 6311 - 20
Salmonella enterica serovar typhimurium-induced maturation of bone marrow-derived dendritic cells; Svensson M et al.; Murine bone marrow-derived dendritic cells (DC) can phagocytose and process Salmonella enterica serovar Typhimurium for peptide presentation on major histocompatibility complex class I (MHC-I) and MHC-II molecules . To investigate if a serovar Typhimurium encounter with DC induces maturation and downregulates their ability to present antigens from subsequently encountered bacteria, DC were pulsed with serovar Typhimurium 24 h prior to coincubating with Escherichia coli expressing the model antigen Crl-OVA . Quantitating presentation of OVA epitopes contained within Crl-OVA showed that Salmonella-pulsed DC had a reduced capacity to process Crl-OVA-expressing E . coli for OVA(257-264)/K(b) and OVA(265-277)/I-A(b) presentation . In addition, time course studies of DC pulsed with Crl-OVA-expressing serovar Typhimurium showed that OVA(257-264)/K(b) complexes could stimulate CD8OVA T-hybridoma cells for <24 h following a bacterial pulse, while OVA(265-277)/I-A(b) complexes could stimulate OT4H T-hybridoma cells for >24 but <48 h . The phoP-phoQ virulence locus of serovar Typhimurium also influenced the ability of DC to process Crl-OVA-expressing serovar Typhimurium for OVA(265-277)/I-A(b) presentation but not for OVA(257-264)/K(b) presentation . Furthermore, pulsing of DC with serovar Typhimurium followed by incubation for 24 or 48 h altered surface expression of MHC-I, MHC-II, CD40, CD54, CD80, and CD86, generating a DC population with a uniform, high expression level of these molecules . Finally, neither the serovar Typhimurium phoP-phoQ locus nor lipopolysaccharides (LPS) containing lipid A modifications purified from phoP mutant strains had a different effect on DC maturation from that of wild-type serovar Typhimurium or purified wild-type LPS . Thus, these data show that Salmonella or Salmonella LPS induces maturation of DC and that this process is not altered by the Salmonella phoP virulence locus . However, phoP did influence OVA(265-277)/I-A(b) presentation by DC infected with Crl-OVA-expressing serovar Typhimurium when quantitated after 2 h of bacterial infection.

Infect Immun, 2000 Nov, 68(11), 6139 - 46
Genetic and functional analysis of a PmrA-PmrB-regulated locus necessary for lipopolysaccharide modification, antimicrobial peptide resistance, and oral virulence of Salmonella enterica serovar typhimurium; Gunn JS et al.; The two-component regulatory system PmrA-PmrB confers resistance of Salmonella spp . to cationic antimicrobial peptides (AP) such as polymyxin (PM), bactericidal/permeability-increasing protein, and azurocidin . This resistance occurs by transcriptional activation of two loci termed pmrE and pmrHFIJKLM . Both pmrE and pmrHFIJKLM produce products required for the biosynthesis of lipid A with 4-aminoarabinose (Ara4N) . Ara4N addition creates a more positively charged lipopolysaccharide (LPS) and thus reduces cationic AP binding . Experiments were conducted to further analyze the regulation of the pmrHFIJKLM operon and the role of this operon and the surrounding genomic region in LPS modification and antimicrobial peptide resistance . The pmrHFIJKLM genes are cotranscribed and over 3,000-fold regulated by PmrA-PmrB . The pmrHFIJKLM promoter bound PmrA, as determined by gel shift analysis, as did a 40-bp region of the PmrA-PmrB-regulated pmrCAB promoter . Construction of nonpolar mutations in the pmrHFIJKLM genes showed that all except pmrM were necessary for the Ara4N addition to lipid A and PM resistance . The flanking genes of the operon (pmrG and pmrD) were not necessary for PM resistance, but pmrD was shown to be regulated by the PhoP-PhoQ regulatory system . BALB/c mice inoculated with pmrA and pmrHFIJKLM mutant strains demonstrated virulence attenuation when the strains were administered orally but not when they were administered intraperitoneally, indicating that Ara4N addition may be important for resistance to host innate defenses within intestinal tissues.

Mutat Res, 2000 Nov 6, 454(1-2), 77 - 88
Antimutagenic effects of wheat bran diet through modification of xenobiotic metabolising enzymes; Helsby NA et al.; Diets containing wheat bran (WB) protect against cancers of the colon or breast in rats, and may be beneficial in humans . In a previous study of rats treated with the carcinogen 2-amino-3-methylimidazo{4,5-f}quinoline (IQ), inclusion of 10% wheat bran in the diet led to an apparent reduction in IQ metabolites but not of intact IQ in plasma . In the present study, male Wistar rats were fed diets containing 0, 10 or 20% wheat bran, and effects on xenobiotic metabolising enzymes compared . Wheat bran-supplementation showed differential effects on phase I enzymes, significantly increasing the activity of hepatic cytochrome P450 isozyme CYP3A2, but slightly reducing the activity of CYP1A1/2 . The activities of both hepatic phase II detoxification enzymes glutathione-S-transferase and glucuronosyl transferase were also reduced . Western blotting revealed similar effects on expression of the proteins . Interestingly, the expression of xenobiotic metabolising enzymes (XME) in the colon appeared to be modulated independently of hepatic XME . Although the wheat bran-supplemented diet still led to an increased expression of CYP3A, it now slightly increased CYP1A in the colon . However, 20% wheat bran significantly increased the expression of both glutathione transferase isozymes, GST A1 & A2, in the colon . Natures Gold (NG) is a commercial wheat bran derivative which is lower than wheat bran in dietary fibre, but enriched in vitamins, minerals and various phytochemicals . Dietary supplementation with 20% Natures Gold led to similar trends as seen in wheat bran-fed rats, but more potent effects in both hepatic and colonic enzymes . The significance of these changes for activation of carcinogens to mutagenic metabolites was investigated using the Salmonella/mammalian microsome mutagenicity test . The activation of IQ and benzo{a}pyrene, but not cyclophosphamide, to a mutagen by hepatic S9 from wheat bran-fed or Natures Gold-fed rats was significantly reduced compared with S9 from animals on a diet lacking wheat bran . We suggest that modulation of xenobiotic metabolising enzymes may be an important component of cancer protection by wheat bran, and this effect may relate to micronutrients or cancer-protective non-nutrient phytochemicals rather more than to dietary fibre.

J Immunol, 2000 Oct 1, 165(7), 4120 - 6
Impairment of STAT activation by IL-12 in a patient with atypical mycobacterial and staphylococcal infections; Gollob JA et al.; IL-12 plays a pivotal role in the stimulation of immune responses against intracellular infections . This role is manifested in the increased susceptibility to atypical mycobacterial and salmonella infections among individuals whose lymphocytes lack expression of IL-12Rbeta1 . Here, we report on a patient with Mycobacterium avium infection, recurrent Staphylococcus aureus sinusitis, and multiple adverse drug reactions whose T cells were unable to produce IFN-gamma or proliferate in response to IL-12 despite the expression of wild-type IL-12Rbeta1 and IL-12Rbeta2 . The defect in these functional responses to IL-12 was selective, as cytolytic activity induced by IL-12 was intact, and lymphocytes were responsive to stimulation by IL-2 . An examination of cytokine signaling revealed that STAT4 and extracellular regulated kinase 1 (ERK1) activation by IL-12 was intact, whereas the activation of STAT1, -3, and -5 by IL-12 was lost . This impairment of STAT activation was specific for IL-12, as STAT activation by IL-2, IL-15, and IFN-gamma was unaffected . These findings demonstrate that the activation of STAT4 alone is not sufficient for IL-12-induced IFN-gamma production and proliferation and suggest that other STATs play a role in these responses to IL-12 . While the etiology of the impaired IL-12 signaling in this patient has not yet been elucidated, the absence of mutations in IL-12Rbeta1 or IL-12Rbeta2 and the preservation of STAT4 activation raise the possibility that there may be a mutation in an as yet undiscovered component of the IL-12 signaling complex that is normally required for the recruitment and activation of STAT1, -3, and -5.

FEMS Microbiol Lett, 2000 Sep 15, 190(2), 341 - 7
Molecular characterisation of emergent multiresistant Salmonella enterica serotype {4,5,12:i:-} organisms causing human salmonellosis; Guerra B et al.; Salmonella multidrug-resistant clinical organisms identified as serotype {4,5,12:i:-} were typed using selected genetic procedures and compared with typhimurium organisms collected in the same Spanish region . Results showed a low genetic heterogeneity among {4,5,12:i:-} organisms, which generated identical ribotypes and similar but not identical XbaI PFGE, RAPD, and plasmid profiles . Multidrug resistance could be eliminated by curing and seems to be mediated by 140-kb (spvC+) and 120-kb (spvC-) non-self-transferable plasmids . The {4,5,12:i:-} organisms fall into a single genetic lineage, which emerged in 1997 and presents a different degree of genetic relationship with typhimurium lineages.

Intensive Care Med, 2000 Aug, 26(8), 1139 - 43
The Pstl polymorphism of the endotoxin-inducible heat-shock protein 70-2 gene does not affect messenger RNA level in human whole-blood cultures; Schroeder S et al.; OBJECTIVE: To determine whether the human leukocyte antigen linked biallelic heat-shock protein 70-2 (HSP70-2) gene polymorphism is associated with variable HSP70-2 messenger RNA expression . DESIGN: Prospective observational study in consecutive healthy blood donors . SETTING: Department of Anesthesiology, laboratory for molecular biology in a university hospital . PARTICIPANTS: 24 healthy blood donors . INTERVENTIONS: None . MEASUREMENTS AND RESULTS: We studied the functional implication of the HSP70-2 (G/A) PstI gene polymorphism in 24 healthy, white blood donors with various HSP70-2 (G/A) genotypes by analyzing the endotoxin-inducible HSP70-2 mRNA expression by means of the reverse transcription-polymerase chain reaction . HSP70 expression was expressed semiquantitatively by calculating the ratio of HSP70-2 mRNA and the constitutively expressed glutaraldehyde 3-phosphate dehydrogenase mRNA . No significant differences in HSP70-2 mRNA expression after lipopolysaccharide (from Salmonella minnesota Re 595) stimulation were detected in individuals homozygous for the allele A (0.68, range 0.38-1, n = 10), in individuals homozygous for the allele G (0.79, range 0.42-1.1, n = 8), and in heterozygotes (HSP70-2 G/A; 0.52, range 0.4-0.67, n = 6; p > 0.05) . CONCLUSIONS: The PstI polymorphism of the endotoxin-inducible HSP70-2 gene is not associated with variable HSP70-2 mRNA expression ex vivo . This finding is in accordance with the observation that HSP70-2 genotypes do not affect clinical outcome in human systemic inflammation.

J Bacteriol, 2000 Nov, 182(21), 6183 - 91
Acquisition of the rfb-gnd cluster in evolution of Escherichia coli O55 and O157; Tarr PI et al.; The rfb region specifies the structure of lipopolysaccharide side chains that comprise the diverse gram-negative bacterial somatic (O) antigens . The rfb locus is adjacent to gnd, which is a polymorphic gene encoding 6-phosphogluconate dehydrogenase . To determine if rfb and gnd cotransfer, we sequenced gnd in five O55 and 13 O157 strains of Escherichia coli . E . coli O157:H7 has a gnd allele (allele A) that is only 82% identical to the gnd allele (allele D) of closely related E . coli O55:H7 . In contrast, gnd alleles of E . coli O55 in distant lineages are >99.9% identical to gnd allele D . Though gnd alleles B and C in E . coli O157 that are distantly related to E . coli O157:H7 are more similar to allele A than to allele D, there are nucleotide differences at 4 to 6% of their sites . Alleles B and C can be found in E . coli O157 in different lineages, but we have found allele A only in E . coli O157 belonging to the DEC5 lineage . DNA 3' to the O55 gnd allele in diverse E . coli lineages has sequences homologous to tnpA of the Salmonella enterica serovar Typhimurium IS200 element, E . coli Rhs elements (including an H-rpt gene), and portions of the O111 and O157 rfb regions . We conclude that rfb and gnd cotransferred into E . coli O55 and O157 in widely separated lineages and that recombination was responsible for recent antigenic shifts in the emergence of pathogenic E . coli O55 and O157.

Int J Food Microbiol, 2000 Oct 1, 61(1), 51 - 62
Estimating the annual fraction of eggs contaminated with Salmonella enteritidis in the United States; Ebel E et al.; Using available data on the occurrence of Salmonella enteritidis (SE) in US layer flocks and eggs, and a probabilistic scenario tree method, an estimate of the fraction of SE-contaminated eggs produced annually is derived with attendant uncertainty . In lieu of a definitive prevalence survey, the approach presented here provides insight to the relative contribution of various pathways leading to contaminated eggs . A Monte Carlo model with four branches is developed . The first branch predicts the proportion of all US flocks that are SE-affected . The second branch apportions SE-affected flocks into three categories (high, moderate, and low level affected flocks) based on population-adjusted epidemiologic data . The third branch predicts the proportion of affected flocks that are molted and producing eggs during a high risk period subsequent to molt . The fourth branch predicts the fraction of contaminated eggs produced by flocks of the type described by the pathway (e.g . high level affected flocks that are not molted) based on egg sampling evidence from naturally infected flocks . The model is simulated to account for uncertainty in the data used to estimate the branch probabilities . Correlation analysis is used to estimate the sensitivity of model output to various model inputs . The output of this model is an uncertainty distribution for the fraction of all eggs that are SE-contaminated during 1 year of production in the US . The expected value of this distribution is approximately one SE-affected egg in every 20,000 eggs annually produced, and the 90% certainty interval is between one SE-contaminated egg in 30,000 eggs, and one SE-contaminated egg in 12,000 eggs . The model estimates that an average of 14% of all eggs (i.e . contaminated and not contaminated) from affected flocks are produced by high level, non-molted affected flocks, but these flocks are estimated to account for more than two-thirds of the total fraction of contaminated eggs produced annually . Sensitivity analysis also suggests that the proportion of affected flocks that are high level flocks - and the egg contamination frequency for these types of flocks - are the most sensitive model inputs . The model's pathways provide a framework for evaluating interventions to reduce the number of contaminated eggs produced in the US . Furthermore, sensitivity analysis of the model identifies those inputs whose uncertainty is most influential on the model's output . Future farm-level research priorities can be established on the basis of this analysis, but public policy decisions require a fuller exposure assessment and dose-response analysis to account for microbial growth dynamics, meal preparation, and consumption demographics among US egg consumers.

Scand J Rheumatol, 2000, 29(4), 226 - 31
BPI-ANCA is found in reactive arthritis caused by Yersinia and Salmonella infection and recognise exclusively the C-terminal part of the BPI molecule; Schultz H et al.; OBJECTIVE: To examine the prevalence, binding sites and functional interactions of antineutrophil cytoplasmic autoantibodies (ANCA) against the bactericidal/permeability increasing protein (BPI) in reactive arthritis (ReA) . METHODS: Sera were analysed for the occurrence of ANCA by indirect immunofluorescence microscopy (IIF) and ELISA . Binding sites were determined using BPI, lipopolysaccharid binding protein (LBP), and fusion proteins of both proteins in ELISA . In addition, the effect of antibodies on the antibiotic activity of BPI was examined . RESULTS: BPI-ANCA was found in patients with Yersinia- and Salmonella-triggered ReA and directed against the C-terminal portion of BPI . Goat anti BPI antibodies recognising this part inhibited the antibiotic activity of BPI in vitro . CONCLUSION: BPI-ANCA was associated with ReA triggered by Salmonella and Yersinia infection . Directed against the C-terminal part of BPI, it can potentially inhibit its antibiotic activity and might be useful to identify patients with infectious bowel disease prone to extraintestinal sequelae.

Onderstepoort J Vet Res, 2000 Jun, 67(2), 129 - 33
Phage types of Salmonella enterica serovar Enteritidis isolated in South Africa from 1991-1995; Mare L et al.; A total of 615 strains of Salmonella enterica serovar Enteritidis (SE), received from 1991-1995 at the Onderstepoort Veterinary Institute (OVI), were phage typed . Most SE isolates (54,7%) originated from poultry followed by humans (28,5 %) and poultry eggs (9,6 %) . Phage type 34 was the most prevalent (40,5 %) of all isolates, followed by phage type 4 (33,8 %) . Other phage types identified were 1, lb, 4a, 7, 7a, 9a, 14, 24, 24var and 35 (in total 2,4% of isolates) . Most isolates of SE were received from the Western Cape Province (47,4%) and Gauteng (22,3%) . In poultry phage type 4 was dominant, but in humans, eggs, goats, ducks, sheep, pigs and rabbits, phage type 34 was the dominant type . It appeared as if the poultry-associated epidemic of SE in South Africa that occurred from 1991-1995 originated in the Western Cape Province during 1991 amongst poultry and then spread from there to humans and eggs and then to the rest of the country, where it emerged during 1993 . Results indicate that phage type 34 was the dominant phage type from 1991-1993, but during 1994-1995 its presence declined . During this latter period the presence of phage type 4 increased . This may suggest that two smaller epidemics consisting of the two different phage types might have been responsible for the epidemic that occurred from 1991-1995.

Clin Immunol, 2000 Nov, 97(2), 146 - 53
Safety and immune responses to attenuated Salmonella enterica serovar typhi oral live vector vaccines expressing tetanus toxin fragment C; Tacket CO et al.; Attenuated Salmonella enterica serovar Typhi vaccine strain CVD 908-htrA was used as a vector to deliver fragment C of tetanus toxin as a single-dose oral tetanus vaccine candidate to elicit protective levels of serum tetanus antitoxin . Twenty-one healthy adult volunteers received doses of 1.6 x 10(7) to 8.2 x 10(9) CFU of one of two strains, CVD 908-htrA(pTETnir15) or CVD 908-htrA(pTETlpp), which contained plasmid-encoded fragment C, with sodium bicarbonate, and the safety and immune responses to serovar Typhi antigens and tetanus toxin were assessed . No volunteer had fever or positive blood cultures after vaccination, although diarrhea occurred in 3 volunteers and vomiting in 2 volunteers within 3 weeks after vaccination . Most volunteers excreted the vaccine strain in the first 72 h after vaccination . Three of nine volunteers who received 10(8) CFU or higher doses of the CVD 908-htrA(pTETlpp) construct developed rises in serum antitoxin antibodies . The serum and cellular immune responses to serovar Typhi antigens were less frequent than those previously observed in volunteers who ingested the parent strain CVD 908-htrA . This study demonstrates that fragment C of tetanus toxin delivered orally to volunteers in an S . Typhi vector can elicit protective levels of serum antitoxin .

FEMS Immunol Med Microbiol, 2000 Oct, 29(2), 81 - 8
Salmonella enteritidis temperature-sensitive mutants protect mice against challenge with virulent Salmonella strains of different serotypes; Gherardi MM et al.; The protection conferred by temperature-sensitive mutants of Salmonella enteritidis against different wild-type Salmonella serotypes was investigated . Oral immunization with the single temperature-sensitive mutant E/1/3 or with a temperature-sensitive thymine-requiring double mutant (E/1/3T) conferred: (i) significant protection against the homologous wild-type Salmonella strains; (ii) significant cross-protection toward high challenge doses of S . typhimurium . Significant antibody levels against homologous lipopolysaccharide and against homologous and heterologous protein antigens were detected in sera from immunized mice . Moreover, a wide range of protein antigens from different Salmonella O serotypes were recognized by sera from immunized animals . Besides, primed lymphocytes from E/1/3 immunized mice recognized Salmonella antigens from different serotypes . Taken together, these results indicate that temperature-sensitive mutants of S . enteritidis are good candidates for the construction of live vaccines against Salmonella.

Lancet, 2000 Sep 2, 356(9232), 829 - 30
Antibacterial properties of xanthine oxidase in human milk; Stevens CR et al.; Formula-fed babies contract gastroenteritis more than breast-fed babies, which is of concern to mothers who cannot breastfeed or, as with HIV-infected mothers, are discouraged from breastfeeding . The ability of endogenous breastmilk xanthine oxidase to generate the antimicrobial radical nitric oxide has been measured and its influence on the growth of Escherichia coli and Salmonella enteritides examined . Breastmilk, but not formula feed, generated nitric oxide . Xanthine oxidase activity substantially inhibited the growth of both bacteria . An important natural antibiotic system is missing in formula feeds; the addition of xanthine oxidase may improve formula for use when breastfeeding is not a safe option.

Vestn Ross Akad Med Nauk, 2000, (8), 41 - 5
{Spatial and temporary changes in sensitivity of murine proliferative system and energy exchange to typhoid fever infection}; Romanov IuA et al.; The authors studied the spatial and temporary organization of the proliferative system and energy exchange in the small intestinal epithelium, as well as spatial and temporary changes in the sensitivity of these systems in mice to typhoid fever infection (cultured Salmonella typhi, 4446) at day and night . The small intestinal epithelial systems were found to show a spatial and time organization and a close correlation between their temporary and spatial changes after infection . The temporary organization of the proliferative system in the esophageal epithelium is more sensitive to infection in the day-time and that of the small intestinal epithelial proliferative system is more marked at night . Thus, these changes are tissue-specific . Typhoid fever infection causes a negative effect on the proliferative system of the small intestine at night and on its energy exchange in the day-time, which shows the system-specific response of the temporary organization of a biological process within the same organ . The changes in the spatial proliferative and energy exchange parameters in the small intestinal epithelium, which have been caused by the infection of animals, depend on the time of a day.

Commun Dis Intell, 2000 Aug, 24(8), 233 - 6
Typhoid and paratyphoid fever in south-eastern Sydney, 1992-1997; Kidenya V et al.; Notification records of typhoid and paratyphoid cases among residents of south-eastern Sydney during 1992-1997 were reviewed, with particular attention paid to identifying a source of infection and to completeness of follow up . Notifications comprised 30 cases of Salmonella Typhi, nine of S . Paratyphi A and five of S . Paratyphi B . These 44 cases had a median age of 20 years (range 2-62) . Of the 39 cases with known country of birth, 30 were born overseas, predominantly in Asian countries . Of 39 cases with a known travel history, 33 were cases of overseas-acquired acute infection and two cases were asymptomatic chronic carriers . A source was identified in only one of four domestically acquired infections . Of eight household contacts in occupations posing a public health risk (seven food-handlers and one health-care worker), complete follow-up information was available for only five . Most cases were in overseas-born individuals who may have been infected when returning to their country of birth . Explicit follow-up protocols need to cover appropriate clinical management (including treatment of chronic carriage) and monitoring of those cases and contacts who could pose a public health risk.

Sante, 2000 May-Jun, 10(3), 205 - 9
{Typhoid and paratyphoid fever in adults in the Internal Medicine Department at Libreville (Gabon)}; Okome-Nkoumou M et al.; We carried out a retrospective study of 150 files of patients suffering from typhoid or paratyphoid fever, confirmed bacteriologically, between January 1992 and December 1996 at Libreville . Young adults were the most frequently affected . These infections were associated with unstable living conditions and lack of cleanliness . Neurological (17%), digestive (12%) and cardiovascular (3%) complications were the principal factors aggravating the disease . The following serotypes were identified: Salmonella typhi (47%), S . paratyphi B (25%), S . paratyphi C (20%) and S . paratyphi A (8%) . Salmonellosis was associated with schistosomiasis (13%), nematodiasis (2.3%), sickle-cell anemia (7%) and HIV infection (8%) . The mortality rate was 3.3% . Fluoroquinolones are the molecules of choice for treating typhoid and paratyphoid fevers.

Eur Cytokine Netw, 2000 Sep, 11(3), 420 - 6
Sublethal hemorrhagic shock reduces tumor necrosis factor-alpha-producing capacity in different cell compartments; Flohe S et al.; Hemorrhagic shock results in a severe impairment of the immune response . Immunological alterations after hemorrhagic shock thus appear to be responsible for reduced resistance to infectious agents commonly observed after shock and severe injury . In the present study we examined the TNF-alpha-producing capacity of immune cells derived from different organs after sublethal shock in rats . Hemorrhagic shock was established by pressure controlled bleeding to a mean arterial pressure of 35 mm Hg for 35-40 min and consecutive resuscitation in male Sprague-Dawley rats . Twenty four hours after shock, TNF-a production in response to lipopolysaccharide (LPS, Salmonella friedenau) stimulation was measured in isolated spleen, bone marrow and blood cells . TNF-a production could be induced by stimulation with 1 ng/ml, in blood, spleen and bone marrow cells collected from sham-operated animals . A maximal stimulation was observed in all cell types after stimulation with 10 ng/ml LPS and could not be further increased with LPS doses of 100 ng/ml . Hemorrhagic shock of 35 mm Hg for 35-40 min, with consecutive resuscitation did not result in mortality, in contrast to a 4 hours lasting hemorrhagic shock resulting in 80% mortality . Blood, spleen or bone marrow cells, harvested from animals 24 hours after sublethal hemorrhagic shock, showed a significantly reduced TNF-alpha production in all cell populations after LPS stimulation . Serum collected from animals 2 hours after sublethal hemorrhagic shock contained an activity not present either before or 24 hours after shock, that downregulated LPS-induced TNF-alpha production in rat whole blood cultures and the murine macrophage cell line J774 . The inhibitory activity present in serum, 2 hours after shock is not IL-10 since this mediator was not detectable in any serum sample . However, in the serum samples with TNF-alpha-inhibitory activity, elevated levels of PGE2 metabolites were found, which suggests the involvement of prostaglandins in trauma-induced immunosuppression . Altered TNF-a expression might be partially explained by an inhibitory activity in the serum already present 2 hours after shock . Since adequate, but not overwhelming TNF-alpha production is essential for host response, the altered cytokine formation might explain local and systemic susceptibility to infections after hemorrhagic shock.

J Appl Microbiol, 2000 Sep, 89(3), 501 - 10
Comparison of two commercial preparations of buffered peptone water for the recovery and growth of Salmonella bacteria from foods; Baylis CL et al.; This study compared the performance of two commercial preparations of buffered peptone water . Performance was assessed in terms of ability to resuscitate and recover low numbers of stressed cells, buffering capacity, growth of Salmonella bacteria in pure culture and growth of Salmonella in food pre-enrichments . Although both the preparations of BPW had similar chemical compositions, differences in their recovery performance were found . Brand A recovered significantly higher numbers of heat-injured Salmonella (mean = 0.57 log10 cfu ml(-1) difference) in pure culture compared with brand B when dealing with very low inoculum levels . Although brand B had higher buffering capacity, the pH at the end of the pre-enrichment was found to be similar in both media, even in foods such as milk powder which showed the greatest decline in pH . Both brands were comparable in their ability to grow unstressed Salmonella from different food types . In unstressed cell studies, similar cell numbers were recovered at the end of a 24 h incubation period from both media, although brand B yielded a higher biomass . In the food study with unstressed cells, performance was related more to the food type and the likely association between this and the level and type of competitor organisms present, rather than to the brand of medium used.

J Appl Microbiol, 2000 Sep, 89(3), 472 - 7
Survival of Salmonella in peanut butter and peanut butter spread; Burnett SL et al.; In 1996, the first documented outbreak of salmonellosis associated with the consumption of peanut butter was reported . This study was undertaken to determine survival characteristics of high (5.68 log10 cfu g(-1)) and low (1.51 log10 cfu g(-1)) inocula of a five-serotype mixture of Salmonella in five commercial peanut butters and two commercial peanut butter spreads . Populations in samples inoculated with 5.68 log10 cfu g(-1) and stored for 24 weeks at 21 or 5 degrees C decreased 4.14-4.50 log10 cfu g(-1) and 2.86-4.28 log10 cfu g(-1), respectively, depending on the formulation . The order of retention of viability was: peanut butter spreads > traditional (regular) and reduced sugar, low-sodium peanut butters > natural peanut butter . Differences in rates of inactivation are attributed to variation in product composition as well as size and stability of water droplets in the colloidal matrix, which may influence nutrient availability . With the exception of natural peanut butter, products initially inoculated with 1.51 log10 cfu of Salmonella g(-1) (32 cfu g(-1)) were positive for the pathogen after storage for 24 weeks at 5 degrees C . At 21 degrees C, however, with the exception of one peanut butter spread, all products were negative for Salmonella after storage for 24 weeks . Post-process contamination of peanut butter and spreads with Salmonella may to result in survival in these products for the duration of their shelf life at 5 degrees C and possibly 21 degrees C, depending on the formulation.

Ned Tijdschr Geneeskd, 2000 Sep 16, 144(38), 1830 - 2
{From gene to disease; mutations in interleukin-12-receptor-beta 1- and interferon-gamma-receptor-1 lead to nontuberculous mycobacterial infections and salmonellosis}; van Dissel JT et al.; In patients with severe and relapsing infections with non-tuberculous mycobacteria and Salmonella autosomal recessive as well as dominant-negative mutations are shown in genes for receptors of type-1 cytokines: the IL-12 receptor and the IFN-gamma receptor . In case of an impaired capacity to produce these cytokines or--given an abnormal receptor--to react to them, the cellular immune reaction does not run a normal course and the susceptibility to infection by intracellular pathogens is enhanced.

Res Vet Sci, 2000 Oct, 69(2), 153 - 8
Serum haptoglobin: an objective indicator of experimentally-induced Salmonella infection in calves; Deignan T et al.; Experimental models of Salmonella -induced gastroenteritis have previously relied on crude subjective clinical markers of infection to assess disease severity . The aim of this study was to investigate the possibility that changes in serum levels of the acute phase protein, haptoglobin, may be used as an objective, quantitative measurement of infection . Eight 3- to 4-week-old animals were challenged with a mixture of three Salmonella serotypes containing 6 x 10(10)bacteria and compared with five animals given a placebo preparation . Animals were monitored and characteristic clinical symptoms of infection; diarrhoeal scores, morbidity scores and rectal temperature, were recorded . Serum samples, from both animal groups, taken prior to challenge and again on days 1, 3, and 5 post-challenge, were analysed for haptoglobin levels using a direct serum binding assay . Prior to challenge, all 13 animals had normal levels of haptoglobin in their serum . By day 3 post-challenge six of eight animals challenged with Salmonella had abnormal serum haptoglobin levels (median level = 212 microg ml(-1)), while haptoglobin levels remained normal in placebo-challenged animals (median level = 0 microg ml(-1)) . The change in haptoglobin levels during the 5-day observation period was statistically significant in the Salmonella -challenged animals (P = 0.0003, H = 16.477) . Serum haptoglobin levels showed a statistical correlation with clinical measures of disease severity; diarrhoeal scores (P = 0.0015, H =8 . 988), morbidity scores (P = 0.0004, H = 15.711) and rectal temperature (P = 0.0001, Z = 4.304) . Thus, serum haptoglobin levels closely reflect the clinical symptoms of infection and are therefore a useful marker of infection severity in salmonellosis in calves .

Poult Sci, 2000 Sep, 79(9), 1246 - 50
Application of the agar gel precipitin test to detect antibodies to Salmonella enterica serovar enteritidis in serum and egg yolks from infected hens; Holt PS et al.; Serological surveillance can be an important component for egg quality assurance programs geared toward controlling problems with Salmonella enterica serovar Enteritidis (S . enteritidis) within a flock . Serum is the primary sample source for the procedures, although egg yolk antibody assays have become popularity in recent years . However, these assays tend to be labor intensive, requiring procedures for extracting antibodies from the yolk followed by assaying the samples . We describe an adaptation of the agar gel precipitin (AGP) test for use in detecting antibodies to S . enteritidis deposited in egg yolks of infected hens . Yolk or sera from infected birds were administered to wells cut into seven-well clusters in an agar gel plate, and detection antigen was added to the center well . The agar gels were incubated for 24 h and then examined for the presence of precipitin lines formed by the interaction of antibody with antigen . Three different antigens were tested: S . enteritidis flagella, SEF14 (a 14-kDa fimbrial protein produced ostensibly by S . enteritidis), and a sodium deoxycholate extract of whole S . enteritidis organism . Flagella and the organism extract detected antibodies to S . enteritidis in the yolk and sera, whereas SEF14 was not reactive . Positive reactions were observed in serum 1 wk postchallenge, whereas in yolks, this was further delayed by 1 wk . The sensitivity of the test was slightly less than the standard microagglutination assay, although specificity was slightly higher, as indicated by results from sera and yolks from birds infected with Salmonella enterica serovar Typhimurium . Simplicity and low labor requirements of the assay would allow for the potential testing of several hundred egg samples within a day, which would make up for test shortcomings due to sensitivity . The AGP test could be an important tool for individuals using serological testing to monitor the S . enteritidis situation within their flocks or as a rapid screen for vaccine responses . The assay could also be used in tandem with other AGP tests to screen for the presence of multiple avian pathogens.

Int J Food Microbiol, 2000 Sep 10, 59(3), 221 - 34
Application of foodborne disease outbreak data in the development and maintenance of HACCP systems; Panisello PJ et al.; Five-hundred and thirty general foodborne outbreaks of food poisoning reported in England and Wales between 1992 and 1996 were reviewed to study their application to the development and maintenance of HACCP systems . Retrospective investigations of foodborne disease outbreaks provided information on aetiological agents, food vehicles and factors that contributed to the outbreaks . Salmonella spp . and foods of animal origin (red meat, poultry and seafood) were most frequently associated with outbreaks during this period . Improper cooking, inadequate storage, cross-contamination and use of raw ingredients in the preparation of food were the most common factors contributing to outbreaks . Classification and cross tabulation of surveillance information relating to aetiological agents, food vehicles and contributory factors facilitates hazard analysis . In forming control measures and their corresponding critical limits, this approach focuses monitoring on those aspects that are critical to the safety of the product . Incorporation of epidemiological data in the documentation of HACCP systems provides assurance that the system is based on the best scientific information available.

Int J Food Microbiol, 2000 Sep 10, 59(3), 211 - 20
Comparison between the growth of Yersinia enterocolitica, listeria monocytogenes, escherichia coli O157:H7 and salmonella spp . in ground beef packed by three commercially used packaging techniques; Nissen H et al.; Growth of the pathogens Yersinia enterocolitica, Listeria monocytogenes, Escherichia coli O157:H7 and strains of Salmonella were compared in ground beef packed in modified atmospheres of 60% CO2/40% N2/0.4% CO (high CO2/low CO mixture), 70% O2/30% CO2 (high O2 mixture) and in chub packs (stuffed in plastic casings) . The ground beef was inoculated with rifampicin-resistant or nalidixic acid/streptomycin-resistant strains of the pathogens (final concentration 10(2) - 10(3) bacteria/g) and stored at 4 and 10 degrees C for up to 14 days . At 4 degrees C the shelf life, based on colour stability and background flora development, was prolonged for the high CO2/low CO mixture compared to the two other packaging methods, but at 10 degrees C the shelf life was < 8 days for all the packaging methods . Growth of Y . enterocolitica was nearly totally inhibited both at 4 and 10 degrees C in the high CO2/low CO mixture, while the bacterial numbers in the samples packed in the high O2 mixture increased from about 5 x 10(2) bacteria/g at day 0 to about 10(4) at day 5 at 4 degrees C and to 10(5) at 10 degrees C . Growth in the chub packs was even higher . L . monocytogenes showed very little growth at 4 degrees C in all treatments . At 10 degrees C there was slow growth from about 5 x 10(3) bacteria/g to about 10(4) at day 5 in the high CO2/low CO mixture, while the numbers in the high O2 mixture and the chub packs were about 10 times higher . Growth of E . coli O157:H7 at 10 degrees C in the ground beef was nearly totally inhibited in both the high CO2/low CO mixture and the high O2 mixture . Growth in the chub packs was higher, as the number of bacteria increased 3 log in 5 days . The Salmonella strains (S . typhimurium, S . dublin, S . enteritidis and S . enterica 61:k:1,5,(7)) in the ground beef stored at 10 degrees C for 5 and 7 days grew to a higher number in the high CO2/low CO mixture than in the high O2 mixture . This study shows that the growth of Y . enterocolitica and L . mononcytogenes in ground beef stored in the high CO2 /low CO mixture was not increased as a result of prolonging the shelf life . However, the observed growth of strains of Salmonella at 10 degrees C in this mixture and in chub packs does emphasise the importance of temperature control during storage.

Int J Food Microbiol, 2000 Sep 10, 59(3), 157 - 65
Predictions of growth for Listeria monocytogenes and Salmonella during fluctuating temperature; Bovill R et al.; We studied the predictive performance of a dynamic modelling approach, combined with predictions from the Food MicroModel software, applied to the growth of Listeria monocytogenes and Salmonella in pasteurised milk, chicken liver pate and minced chicken, under constant as well as fluctuating temperatures . We found that, in general, the accuracy of a prediction under fluctuation temperature was similar to that under constant temperature . Generally, there was a good agreement between predictions and observations . However, the growth of Listeria monocytogenes in pasteurised milk was inhibited largely by the natural flora present.

FEBS Lett, 2000 Sep 29, 482(1-2), 81 - 4
Biophysical characterization of SipA, an actin-binding protein from Salmonella enterica; Mitra K et al.; An essential step in the pathogenesis of Salmonella enterica infections is bacterial entry into non-phagocytic cells of the intestinal epithelium . Proteins injected by Salmonella into host cells stimulate cellular responses that lead to extensive actin cytoskeleton reorganization and subsequent bacterial uptake . One of these proteins, SipA, modulates actin dynamics by directly binding to F-actin . We have biophysically characterized a C-terminal fragment, SipA(446-684), which has previously been shown to retain activity . Our results show that SipA(446-684) exhibits an elongated shape with a predominantly helical conformation and predict the existence of a coiled-coil domain . We suggest that the protein is able to span two adjacent actin monomers in a filament and propose a model that is consistent with the observed effects of SipA(446-684) on actin dynamics and F-actin stability and morphology.

Annu Rev Microbiol, 2000, 54, 735 - 74
Assembly and function of type III secretory systems; Cornelis GR et al.; Type III secretion systems allow Yersinia spp., Salmonella spp., Shigella spp., Bordetella spp., and Pseudomonas aeruginosa and enteropathogenic Escherichia coli adhering at the surface of a eukaryotic cell to inject bacterial proteins across the two bacterial membranes and the eukaryotic cell membrane to destroy or subvert the target cell . These systems consist of a secretion apparatus, made of approximately 25 proteins, and an array of proteins released by this apparatus . Some of these released proteins are "effectors," which are delivered into the cytosol of the target cell, whereas the others are "translocators," which help the effectors to cross the membrane of the eukaryotic cell . Most of the effectors act on the cytoskeleton or on intracellular-signaling cascades . A protein injected by the enteropathogenic E . coli serves as a membrane receptor for the docking of the bacterium itself at the surface of the cell . Type III secretion systems also occur in plant pathogens where they are involved both in causing disease in susceptible hosts and in eliciting the so-called hypersensitive response in resistant or nonhost plants . They consist of 15-20 Hrp proteins building a secretion apparatus and two groups of effectors: harpins and avirulence proteins . Harpins are presumably secreted in the extracellular compartment, whereas avirulence proteins are thought to be targeted into plant cells . Although a coherent picture is clearly emerging, basic questions remain to be answered . In particular, little is known about how the type III apparatus fits together to deliver proteins in animal cells . It is even more mysterious for plant cells where a thick wall has to be crossed . In spite of these haunting questions, type III secretion appears as a fascinating trans-kingdom communication device.

Annu Rev Microbiol, 2000, 54, 519 - 65
Bacterial virulence gene regulation: an evolutionary perspective; Cotter PA et al.; Coevolution between bacteria and their plant or animal hosts determines characteristics of the interaction, the bacterial virulence genes involved, and the regulatory systems controlling expression of virulence genes . The long-standing association between Salmonellae and their animal hosts has resulted in the acquisition by Salmonella subspecies of a variety of virulence genes and the evolution of complex regulatory networks . The particular repertoire of virulence genes acquired by different Salmonella enterica subspecies and the regulatory systems that control them dictate subspecies-specific infection characteristics . Although the association between Vibrio cholerae and humans appears to be more recent, to reflect a simpler pathogenic strategy, and to involve fewer virulence genes than that of Salmonellae, complex virulence-regulatory networks have nonetheless evolved . In contrast, there is no evidence for acquisition of virulence genes by horizontal gene transfer in bordetellae, and their virulence regulon is less complex in overall structure than those of salmonellae and Vibrio cholerae . In Bordetellae, subspecies-specific differences in pathogenic strategy appear to result from differential gene expression within and across Bordetella subspecies.

Proc Natl Acad Sci U S A, 2000 Oct 10, 97(21), 11227 - 31
Plasmid-encoded MucB protein is a DNA polymerase (pol RI) specialized for lesion bypass in the presence of MucA', RecA, and SSB; Goldsmith M et al.; Replication through damaged sites in DNA requires in Escherichia coli the SOS stress-inducible DNA polymerase V (UmuC), which is specialized for lesion bypass . Homologs of the umuC gene were found on native conjugative plasmids, which often carry multiple antibiotic-resistant genes . MucB is a UmuC homolog present on plasmid R46, and its variant plasmid pKM101 has been introduced into Salmonella strains for use in the Ames test for mutagens . Using a translesion replication assay based on a gapped plasmid carrying a site-specific synthetic abasic site in the single-stranded DNA region, we show that MucB is a DNA polymerase, termed pol RI, which is specialized for lesion bypass . The activity of pol RI requires the plasmid-encoded MucA' protein and the E . coli RecA and single-strand DNA binding proteins . Elimination of any of the proteins from the reaction abolished lesion bypass and polymerase activity . The unprocessed MucA could not substitute for MucA' in the bypass reaction . The presence of a lesion bypass DNA polymerase on a native conjugative plasmid, which has a broad host range specificity and carries multiple antibiotic-resistant genes, raises the possibility that mutagenesis caused by pol RI plays a role in the spreading of antibiotic resistance among bacterial pathogens.

Mol Gen Genet, 2000 Sep, 264(1-2), 184 - 92
Regulation of septation: a novel role for SerC/PdxF in Salmonella?
Mouslim C, Cano DA, Flores A, Casadesus J.
The sfiW locus of Salmonella enterica, previously identified by mutations that suppress the cell division defect of His-constitutive (His(c)) strains, corresponds to serC, the bifunctional gene for phosphoserine-oxoglutarate aminotransferase (SerC) and 2-ketoerythroic acid 4-phosphate transaminase (PdxF) . SerC- mutants form small, nearly spherical cells in a wild-type (His+) background, suggesting that the SerC/PdxF product acts as a septation antagonist . Suppression of His(c) filamentation by serC mutations may be explained by loss of the anti-septation activity of SerC/PdxF . The isolation of serC alleles that have lost their biosynthetic activities but are still able to inhibit septum formation suggests that the anti-septation activity of the SerC/PdxF product is unrelated to its known roles in serine and pyridoxine biosynthesis.

Int J Food Microbiol, 2000 Sep 25, 60(2-3), 269 - 85
Stressed salmonella are exposed to reactive oxygen species from two independent sources during recovery in conventional culture media; Stephens PJ et al.; Previously, Stephens et al . {J . Appl . Microbiol . 83 (1997) 445-455} developed a sensitive technique for studying the resuscitation of low levels of stressed Salmonella . Using this technique the influence on recovery performance of the peptone component of buffered peptone water was investigated . Within 12 different peptone types as much as 3.5 log10 cells/ml difference was observed between the best and worst performing formulations . Poor recovery performance was linked to reactive oxygen species (ROS) generation through auto-oxidation of reducing sugars and photo-sensitisation of sensitive components such as riboflavin . Supplementary recovery agents were explored with only Oxyrase, which has both enzymes to degrade ROS and the ability to rapidly turn a medium anaerobic, having any significant effect . It improved the speed of recovery and increased, by up to 100-fold, the number of stressed cells recovered . Stressed cells were further studied by flow cytometry with cell sorting, based on the staining pattern from a novel fluorochrome combination, into good and poor recovery media . It was identified that within a stressed population the removal of all oxygen protected actively respiring cells the most by forcing them to generate energy from anaerobic metabolism thus avoiding any risk from accidental endogenous ROS generation . The recognition of two independent sources of oxidative stress in the routine use of conventional culture media is discussed in relation to pathogen detection and other areas of food microbiology.

Int J Food Microbiol, 2000 Sep 25, 60(2-3), 153 - 61
Permeability barrier of the gram-negative bacterial outer membrane with special reference to nisin; Helander IM et al.; The effect of nisin pretreatment on organic acid-induced permeability increase in strains of Escherichia coli, Pseudomonas aeruginosa, P . marginalis, and Salmonella enterica sv . Typhimurium was investigated, using assays based on the uptake of a fluorescent dye 1-N-phenylnaphthylamine (NPN) and on the bacterial susceptibility to detergent-induced bacteriolysis . The outer membrane of bacteria which had been pretreated with nisin was shown to be less stable against 1 mM EDTA, as indicated by their significantly higher NPN uptake levels as compared to untreated bacteria . Upon challenge with a tenfold lower concentration of EDTA (0.1 mM) some nisin-treated strains (Typhimurium, P . marginalis) exhibited, however, NPN uptake levels which were lower than those seen in control bacteria, suggesting that nisin had stabilized their outer membrane . Nisin pretreatment also decreased the NPN uptake induced by citric or lactic acid or both in E . coli, P . marginalis, and Typhimurium, whereas in P . aeruginosa the pretreatment resulted in increased NPN uptake in response to citric and lactic acid . These results suggest that, with the exception of P . aeruginosa, nisin could protect bacteria from the outer membrane-disrupting effect caused by the acids . P . aeruginosa was, however, shown to be protected against bacteriolysis induced by the detergents sodium dodecylsulfate and Triton X-100 . With a pair of isogenic mutants of Typhimurium differing in their cell surface charge it was shown that the NPN uptake response to I mM EDTA of the abnormally cationic strain was not significantly affected by nisin, whereas in the normal anionic strain nisin strongly strengthened the uptake . Our hypothesis based on these findings is that the normally anionic cell surface of Gram-negative bacteria has a tendency to bind the cationic nisin . The binding of nisin to the surface does not proceed to the cytoplasmic membrane, but in the outer membrane the bound nisin actually stabilizes its structure through electrostatic interactions . With the exception of EDTA, the organic acids at pH 4 did not cause leakage of cell contents from Typhimurium, indicating that these acids do not permeabilize the outer membrane to an extent required for cytoplasmic pore formation by nisin.

J Clin Microbiol, 2000 Oct, 38(10), 3631 - 5
Comparison of Danish isolates of Salmonella enterica serovar enteritidis PT9a and PT11 from hedgehogs (Erinaceus europaeus) and humans by plasmid profiling and pulsed-field gel electrophoresis; Nauerby B et al.; During the years 1994 to 1998, 10 strains of Salmonella enterica serovar Enteritidis phage type 11 (PT11) and 6 PT9a strains were isolated from Danish hedgehogs, together with 7 strains that did not yield phage susceptibility patterns conforming with any known phage type (routine dilution no conformity {RDNC}) . From 1995 to 1998, five Danish patients were reported infected with serovar Enteritidis PT11 and two with PT9a . All serovar Enteritidis PT11, PT9a, and RDNC isolates from hedgehogs and humans were analyzed by pulsed-field gel electrophoresis (PFGE), plasmid profiling, and restriction fragment length polymorphism (RFLP) of plasmids . By use of S1 nuclease and HindIII, the PT11 and PT9a isolates had identical plasmid profiles and RFLP patterns, which differed from the RDNC profiles . The PFGE profiles were identical for all serovar Enteritidis PT11 and PT9a strains from hedgehogs, four of five human strains of serovar Enteritidis PT11, and two human strains of serovar Enteritidis PT9a, irrespective of restriction enzyme, whereas the last human strain deviated slightly when NotI was used but not when XbaI or SpeI was used . The results indicate that serovar Enteritidis PT9a and PT11 are closely related and that PT11 and PT9a from Danish hedgehogs and humans belong to the same clonal lineage.

Ugeskr Laeger, 2000 Sep 18, 162(38), 5092 - 3
{A complicated course of Salmonella gastroenteritis during antihypertensive treatment}; Sondergaard SB et al.; Although Salmonella gastroenteritis usually is a fairly mild and self-limiting disease, serious complications are sometimes seen . We present a case that was further complicated by treatment with enalapril . We recommend discontinuation of treatment with ACE inhibitors in patients with any kind of ongoing gastroenteritis with fluid loss in order to prevent a potentially serious outcome.

Schweiz Med Wochenschr, 2000 Aug 26, 130(34), 1185 - 91
Clinical features and analysis of the duration of colonisation during an outbreak of Salmonella braenderup gastroenteritis; Rossier P et al.; During an outbreak of acute Salmonella braenderup gastroenteritis we performed a standardised interview encompassing questions on clinical symptoms in 156 (127 adults and 29 children) of 215 identified patients . Sequential stool cultures were obtained for up to five months in these 156 cases . We restricted the analysis to the 122 patients with at least 3 or more available cultures . They were treated with a fluoroquinolone, trimethoprim-sulfamethoxazole, or not treated with antibiotics, according to the decision of the practitioners . For this reason, a randomised double blind study was not possible . Minimum inhibitory concentrations (MIC) of the prescribed drugs were measured for representative isolates before and after treatment . The most frequent symptoms were diarrhoea (98%) and abdominal pain (96%) . Vomiting occurred in 43% of cases . Children were more severely ill . Seven weeks after acute gastroenteritis, stool cultures were still positive for salmonella in 71% of the 22 children and 30% of the 100 adults examined (p < 0.002) . This rate decreased progressively in both groups to 5 and 3% respectively at 20 weeks (n.s.) . Among adults, no significant difference in enteric carriage over time could be demonstrated between untreated patients and those treated with either a fluoroquinolone or trimethoprim-sulfamethoxazole . MIC for salmonella isolates remained unchanged after treatment . In a cohort of patients infected with a single strain of salmonella, fluoroquinolone therapy of acute gastroenteritis failed to influence the duration of enteric carriage, despite continuing susceptibility of the strain . In children, the rate of clearance of Salmonella braenderup from stool was statistically lower until the tenth week after the acute disease, but there was no further difference after 5 months.

Appl Environ Microbiol, 2000 Oct, 66(10), 4539 - 42
Improved template preparation for PCR-based assays for detection of food-borne bacterial pathogens; Lampel KA et al.; Shigella flexneri, Salmonella enterica serotype Typhimurium, and Listeria monocytogenes were applied to FTA filters, and the filters were used directly as templates to demonstrate their sensitivity and applicability in PCR-based detection assays . With pure cultures, the sensitivities of detection by FTA filter-based PCR were 30 to 50 and 200 CFU for the gram-negative enterics and Listeria, respectively . Different numbers of S . flexneri cells were used in controlled contamination experiments with several different foods (produce, beef, and apple cider) . Aliquots from concentrated food washes subsequently spotted onto FTA filters and assayed by PCR gave consistently positive results and detection limits similar to those observed with pure-culture dilutions . This universal method for PCR template preparation from bacterial cells is rapid and highly sensitive and reduces interference from food-associated inhibitors of PCR . In addition, its broad applicability eliminates the need for multiple methods for analysis of food matrices.

Appl Environ Microbiol, 2000 Oct, 66(10), 4414 - 20
Vesicle-mediated transfer of virulence genes from Escherichia coli O157:H7 to other enteric bacteria; Yaron S et al.; Membrane vesicles are released from the surfaces of many gram-negative bacteria during growth . Vesicles consist of proteins, lipopolysaccharide, phospholipids, RNA, and DNA . Results of the present study demonstrate that membrane vesicles isolated from the food-borne pathogen Escherichia coli O157:H7 facilitate the transfer of genes, which are then expressed by recipient Salmonella enterica serovar Enteritidis or E . coli JM109 . Electron micrographs of purified DNA from E . coli O157:H7 vesicles showed large rosette-like structures, linear DNA fragments, and small open-circle plasmids . PCR analysis of vesicle DNA demonstrated the presence of specific genes from host and recombinant plasmids (hly, L7095, mobA, and gfp), chromosomal DNA (uidA and eaeA), and phage DNA (stx1 and stx2) . The results of PCR and the Vero cell assay demonstrate that genetic material, including virulence genes, is transferred to recipient bacteria and subsequently expressed . The cytotoxicity of the transformed enteric bacteria was sixfold higher than that of the parent isolate (E . coli JM109) . Utilization of the nonhost plasmid (pGFP) permitted the evaluation of transformation efficiency (ca . 10(3) transformants microg of DNA(-1)) and demonstrated that vesicles can deliver antibiotic resistance . Transformed E . coli JM109 cells were resistant to ampicillin and fluoresced a brilliant green . The role vesicles play in genetic exchange between different species in the environment or host has yet to be defined.

J Pediatr Orthop, 2000 Sep-Oct, 20(5), 682 - 5
Retrospective review of osteoarticular infections in a pediatric sickle cell age group; Chambers JB et al.; Patients with sickle cell disease have been documented to be particularly susceptible to osteoarticular infections . Controversy exists concerning the bacteriology, etiology, and clinical presentation in differentiating osteoarticular infections from bone infarct . We retrospectively reviewed all cases from our institution over the past 22 years of osteoarticular infections in children who carry the diagnosis of sickle cell disease . Two thousand consecutive patient charts of children enrolled in the Pediatric Sickle Cell Clinic of our institution between 1973 and 1995 were evaluated . There were 14 cases of bone or joint infections (10 osteomyelitis, four septic arthritis) . There was one case of multicentric osteomyelitis and one case of meningitis complicating the septic arthritis . There were nine male and five female patients with ages ranging from 6 months to 17 years (mean, 8.0) . All patients were noted to have hemoglobin SS . The predominant presenting symptoms were pain (79% of cases) and swelling (71% of cases) . The most frequent physical findings were fever >38.2 degrees C (71% of cases) and tenderness (86% of cases) . Ninety-three percent of the children had a white blood count exceeding 15,000/mm3 (range, 7,900-32,300) . Westergren sedimentation rates ranged from 14 to 89 mm/h with 93% of the children exceeding the normal value in our hospital . Cultures were positive in 75% of tissue biopsies, 58% of the blood cultures, and 70% of the bone or joint aspirates . The most common offending organism found in osteomyelitis was Salmonella (eight of 10 cases); however, no predominant organism found was identified in cases of septic arthritis . Radiographs and bone scans were of limited value in the differential diagnosis between osteoarticular infections and bone infarction . Early diagnosis and treatment of osteoarticular infections is key to satisfactory outcome . This study suggests that an ill-appearing patient with a fever >38.2 degrees C, pain, and swelling should prompt the physician to aspirate or biopsy the area and not rely on diagnostic studies that we found to be unreliable.

Avian Dis, 2000 Jul-Sep, 44(3), 519 - 26
A case study on Salmonella enteritidis (SE) origin at three egg-laying farms and its control with an S . enteritidis bacterin; Yamane Y et al.; In the early 1990s, three egg-laying farms (farms S, T, and B) were thought to have the possibility of Salmonella enteritidis (SE) contamination because positive liquid egg samples originated from those farms . The present study was therefore conducted . The first clarification for SE contamination was the study on the origin of SE contamination including its vertical transmission . The results of SE contamination profiling with dust and manure, food materials, dead embryos, and residual yolks on hatch day in regular monitoring over a few years were clearly negative . Therefore, we concluded the SE transmission/infection was attributed to horizontal infection in the egg-laying farms but not vertical transmission from parental stock, hatcheries, growth, or food materials during a 7-yr experimental period . Second, we attempted to clarify if administration of an SE bacterin (Layermune SE) to growth flocks for the egg-laying farms could reduce SE incidence in liquid egg samples from each egg-laying farm . In the first experiment, we compared SE incidence in liquid egg samples from vaccinated and nonvaccinated flocks (similar age flocks) . SE incidence from vaccinated and nonvaccinated flocks showed negative and <2 most probable number (MPN)/100 ml for farm B, <2 and >1600 MPN/100 ml for farm S, and negative and >1600 MPN/100 ml for farm T, respectively . In the second experiment, we compared the SE isolation incidence in the liquid egg samples from nonvaccinated and newly replaced vaccinated flocks in the same chicken houses from each of the three egg-laying farms . SE incidence in the liquid egg samples was similar to that in the first experiment . Therefore, the SE bacterin may play an important role in reducing the SE incidence of liquid egg samples.

Eur J Med Chem, 2000 Sep, 35(9), 853 - 7
Synthesis and antibacterial activity of some 5-guanylhydrazone/thiocyanato-6-arylimidazo{2,1-b}-1,3, 4-thiadiazole-2-sulfonamide derivatives; Gadad AK et al.; 6-Arylimidazo{2,1-b}-1,3,4-thiadiazole-2-sulfonamides 3 on Vilsmeier-Haak reaction produced 5-formyl-6-arylimidazo{2,1-b}-1,3, 4-thiadiazole-2-{N-(dimethylaminomethino)}sulfonamides 4, while 3 on treatment with potassium thiocyanate in the presence of bromine in acetic acid produced 5-thiocyanato-2-sulfonamides 6 . Interaction of 4 with aminoguanidine hydrochloride in ethanol produced the corresponding 5-guanylhydrazone derivatives 5 . Compounds 5 and 6 showed a high degree of antibacterial activity against both Escherichia coli and Staphylococcus aureus comparable to that of sulfamethoxazole and Norfloxacin . However, they were found to show moderate activity against Salmonella typhi, Pseudomonas aeruginosa and Pneumococci.

Mutat Res, 2000 Sep 20, 453(1), 51 - 65
Mutation spectra in Salmonella of analogues of MX: implications of chemical structure for mutational mechanisms; DeMarini DM et al.; We determined the mutation spectra in Salmonella of four chlorinated butenoic acid analogues (BA-1 through BA-4) of the drinking water mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and compared the results with those generated previously by us for MX and a related compound, MCF . We then considered relationships between the properties of mutagenic potency and mutational specificity for these six chlorinated butenoic acid analogues . In TA98, the three most potent mutagens, BA-3, BA-4, MX, and the organic extract, all induced large percentages of complex frameshifts (33-67%), which distinguish these agents from any other class of compound studied previously . In TA100, which has only GC sites for mutation recovery, >71% of the mutations induced by all of the agents were GC-->TA transversions . The availability of both GC and TA sites for mutation in TA104 resulted in greater distinctions in mutational specificity than in TA100 . MX targeted GC sites almost exclusively (98%); the structurally similar BA-4 and BA-2 produced mutations at similar frequencies at both GC and AT sites; and the structurally similar BA-3 and BA-1 induced most mutations at AT sites (69%) . Thus, large variations in structural properties influencing relative mutagenic potency appeared to be distinct from the more localized similar structural features influencing mutagenic specificity in TA104 . Among a set of physicochemical properties examined for the six butenoic acids, a significant correlation was found between pK(a) and mutagenic potency in TA100, even when the unionized fraction of the activity dose was considered . In addition, a correlation in CLOGP for BA-1 to BA-4 suggested a role for bioavailability in determining mutagenic potency . These results illustrate the potential value of structural analyses for exploring the relationship between chemical structure and mutational mechanisms . To our knowledge, this is the first study in which such analyses have been applied to structural analogues for which both mutagenic potency and mutation spectra date were available.

Mutat Res, 2000 Sep 20, 453(1), 35 - 44
Dose finding in the Ames Salmonella assay; Khromov-Borisov NN et al.; Threshold dose/concentration values, such as the lowest effective dose, minimum effective dose or the lowest effective concentration (LED, MED or LEC, respectively) are in use as an alternative to the mutagen potency measures based on the 'rate' measurements (e.g., the slope of the initial part of the dose-response curve) . In this respect, several statistical procedures for the corresponding so-called 'dose finding' were proposed during the last decades . However, most of them disregard the discrete nature of responses such as the plate colony count in the Ames Salmonella assay . When the plate counts agree with the Poisson assumption, two procedures considered here seem to be appropriate for the dose finding . One is based on the stepwise collapsing of the homogeneous control and dose counts; another consists of constructing the confidence limits for the mutation induction factor (MIF) . When the dose and control counts are non-overlapping, the simple 'visual' non-parametric estimation of LED is possible . Applicability and validity of the methods is demonstrated with the two data sets on the mutagenicity of the beta-carboline alkaloid, harmine, and one of the oxidation products of apomorphine.

FEMS Microbiol Lett, 2000 Oct 1, 191(1), 11 - 6
The colanic acid gene cluster of Salmonella enterica has a complex history; Stevenson G et al.; The colanic acid gene cluster of Salmonella enterica LT2 was sequenced and compared with that of Escherichia coli K-12 . The two clusters are similar with divergence slightly higher than average for genes of the two species . The cluster was divided into four blocks by GC content and seems likely to have transferred from a higher GC content species to the ancestor of E . coli and S . enterica . All 19 genes of K-12 and 13 genes of LT2 appear to have undergone random genetic drift with amelioration of the GC content . However, in the case of S . enterica, we believe that the six genes of the GDP-fucose pathway group were replaced relatively recently by genes closely related to those of the original donor species . Two repetitive elements were observed: a bacterial interspersed mosaic element in the intergenic region between wzx and wcaK in K-12 only and a RSA (repetitive sequence element) sequence between wcaJ and wzx in LT2 only.

J Bacteriol, 2000 Oct, 182(20), 5922 - 4
No genetic barriers between Salmonella enterica serovar typhimurium and Escherichia coli in SOS-induced mismatch repair-deficient cells; Matic I et al.; Conjugational crosses trigger SOS induction in Escherichia coli F(-) cells mated with Salmonella enterica serovar Typhimurium Hfr donors . Using an epigenetic indicator of SOS induction, we showed that a strong SOS response occurring in a subpopulation of mated mismatch repair-deficient cells totally abolishes genetic barriers between these two genera.

J Bacteriol, 2000 Oct, 182(20), 5864 - 71
Identification of a copper-responsive two-component system on the chromosome of Escherichia coli K-12; Munson GP et al.; Using a genetic screen we have identified two chromosomal genes, cusRS (ylcA ybcZ), from Escherichia coli K-12 that encode a two-component, signal transduction system that is responsive to copper ions . This regulatory system is required for copper-induced expression of pcoE, a plasmid-borne gene from the E . coli copper resistance operon pco . The closest homologs of CusR and CusS are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: PcoR and PcoS from the pco operon of E . coli; CopR and CopS from the cop operon, which provides copper resistance to Pseudomonas syringae; and SilR and SilS from the sil locus, which provides silver ion resistance to Salmonella enterica serovar Typhimurium . The genes cusRS are also required for the copper-dependent expression of at least one chromosomal gene, designated cusC (ylcB), which is allelic to the recently identified virulence gene ibeB in E . coli K1 . The cus locus may comprise a copper ion efflux system, because the expression of cusC is induced by high concentrations of copper ions . Furthermore, the translation products of cusC and additional downstream genes are homologous to known metal ion antiporters.

J Bacteriol, 2000 Oct, 182(20), 5787 - 92
sigma(54) Promoters control expression of genes encoding the hook and basal body complex in Rhodobacter sphaeroides; Poggio S et al.; Gene expression of the flagellar system is tightly controlled by external stimuli or intracellular signals . A general picture of this regulation has been obtained from studies of Salmonella enterica serovar Typhimurium . However, these regulatory mechanisms do not apply to all bacterial groups . In this study, we have investigated regulation of the flagellar genetic system in Rhodobacter sphaeroides . Deletion analysis, site-directed mutagenesis, and 5'-end mapping were conducted in order to identify the fliO promoter . Our results indicate that this promoter is recognized by the factor sigma(54) . Additionally, 5'-end mapping of the flgB and fliK transcripts suggests that these mRNAs are also transcribed from sigma(54) promoters . Finally, we showed evidence that suggests that fliC transcription is not entirely dependent on the presence of a complete basal body-hook structure . Our results are discussed in the context of a possible regulatory hierarchy controlling flagellar gene expression in R . sphaeroides.

J Biotechnol, 2000 Sep 29, 83(1-2), 125 - 35
Construction and immunogenicity in mice of attenuated Salmonella typhi expressing Plasmodium falciparum merozoite surface protein 1 (MSP-1) fused to tetanus toxin fragment C; Wu S et al.; One strategy to develop a multi-antigen malaria vaccine is to employ live vectors to carry putative protective Plasmodium falciparum antigens to the immune system . The 19 kDa carboxyl terminus of P . falciparum merozoite surface protein 1 (MSP-1), which is essential for erythrocyte invasion and is a leading antigen for inclusion in a multivalent malaria vaccine, was genetically fused to fragment C of tetanus toxin and expressed within attenuated Salmonella typhi CVD 908 . Under conditions in the bacterial cytoplasm, the fragment C-MSP-1 fusion did not form the epidermal growth factor (EGF)-like domains of MSP-1; monoclonal antibodies failed to recognize these conformational domains in immunoblots of non-denatured protein extracted from live vector sonicates . The MSP-1 was nevertheless immunogenic . One month following intranasal immunization of BALB/c mice with the live vector construct, four out of five mice exhibited > or =four-fold rises in anti-MSP-1 by ELISA (GMT=211); a single intranasal booster raised titers further (GMT=1280) . Post-immunization sera recognized native MSP-1 on merozoites as determined by indirect immunofluorescence . These data encourage efforts to optimize MSP-1 expression in S . typhi (e.g . as a secreted protein), so that the EGF-like epitopes, presumably necessary for stimulating protective antibodies, can form.

J Assoc Physicians India, 1999 Jun, 47(6), 637 - 8
Klebsiella pneumoniae--an emerging bacterial cause of osteomyelitis in sickle cell disease; Hiran S et al.; Salmonella species is the accepted organism causing osteomyelitis in sickle cell disease . Klebsiella pneumoniae is now emerging as a new etiological agent . We report a case of sickle cell osteomyelitis due to Klebsiella pneumoniae.

Emerg Infect Dis, 2000 Sep-Oct, 6(5), 443 - 8
Competitive exclusion of Salmonella enteritidis by Salmonella gallinarum in poultry; Rabsch W et al.; Salmonella Enteritidis emerged as a major egg-associated pathogen in the late 20th century . Epidemiologic data from England, Wales, and the United States indicate that S . Enteritidis filled the ecologic niche vacated by eradication of S . Gallinarum from poultry, leading to an epidemic increase in human infections . We tested this hypothesis by retrospective analysis of epidemiologic surveys in Germany and demonstrated that the number of human S . Enteritidis cases is inversely related to the prevalence of S . Gallinarum in poultry . Mathematical models combining epidemiology with population biology suggest that S . Gallinarum competitively excluded S . Enteritidis from poultry flocks early in the 20th century.

Mol Microbiol, 2000 Sep, 37(6), 1494 - 503
FliH, a soluble component of the type III flagellar export apparatus of Salmonella, forms a complex with FliI and inhibits its ATPase activity; Minamino T et al.; Both FliH and the ATPase FliI are cytoplasmic components of the Salmonella type III flagellar export apparatus . Dominance and inhibition data have suggested that the N-terminus of FliI interacts with FliH and that this interaction is important for the ATPase function of the C-terminal domain of FliI . N-terminally histidine-tagged, wild-type FliI retarded untagged FliH in a Ni-NTA affinity chromatography assay, as did N-His-tagged versions of FliI carrying catalytic mutations . In contrast, N-His-tagged FliI carrying the double mutation R7C/L12P did not, further indicating that the N-terminus of FliI is responsible for interaction with FliH . Native agarose gel electrophoresis confirmed that FliH and FliI form a complex . Analytical gel filtration with in-line multiangle light scattering indicated that FliH alone forms a dimer, FliI alone remains as a monomer, and FliH and FliI together form a (FliH)2FliI complex . Ni-NTA affinity chromatography using N-His-tagged FliH and a large excess of untagged FliH confirmed that FliH forms a homodimer . The ATPase activity of the FliH-FliI complex was about 10-fold lower than that of FliI alone; the presence or absence of ATP did not affect the formation of the complex . We propose that FliH functions as a negative regulator to prevent FliI from hydrolysing ATP until the flagellar export apparatus is competent to link this hydrolysis to the translocation of export substrates across the plane of the cytoplasmic membrane into the lumen of the nascent flagellar structure.

Mol Microbiol, 2000 Sep, 37(6), 1417 - 35
Aggregation of host endosomes by Salmonella requires SPI2 translocation of SseFG and involves SpvR and the fms-aroE intragenic region; Guy RL et al.; Salmonella-induced aggregation of host endosomal compartments into tubules, termed lgp-tubules, requires sifA and ompR . Lgp-tubules result from Salmonella-directed alteration of the endocytic system and typify the unique intracellular locale where Salmonella replicate . A high-throughput method devised to screen 11 520 MudJ mutants for loss of lgp-tubule formation identified one auxotrophic and nine prototrophic mutants . Molecular characterization identified four new loci required to alter epithelial endocytic structure . Salmonella pathogenicity island 2 (SPI2) is the locus central to the phenotype . A subset of SPI2 effectors is essential: SpiC and SseFG are required, but not SseE . A subset of apparatus proteins is also implicated: SsaJ, L, M, V and P are required . SPI2 was implicated further, as SifA shows similarity with known SPI2 translocation targets, and OmpR regulates SPI2 . Another locus lies within the smf-aroE intragenic region . Lgp-tubule formation also involves a locus on the virulence plasmid pSLT . The pSLT-encoded SpvR negatively regulates an unknown repressor of the phenotype located on pSLT . Finally, disruption of carB leads to multiple auxotrophy that prevents lgp-tubule formation . This study demonstrates that lgp-tubule formation is a virulence mechanism that underlies the selective disruption of host endocytic trafficking and is associated with the formation of a replication-permissive locale.

Acta Microbiol Pol, 2000, 49(1), 75 - 82
Role and behaviour of the hydrophobic conditions in bacterial adhesion to incurrent siphon in a bivalve mollusc; Llanos J et al.; Surface hydrophobicity is a widely distributed characteristic among human bacterial pathogens playing an important role in microbes retention by the incurrent siphon of a marine bivalve . Feeding retention experiments with the bivalve Mesodesma donacium was done with hydrophobic strains alone (Staphylococcus aureus, Salmonella paratyphi, Vibrio cholerae) or with mixed cultures using a hydrophilic strain (Aeromonas hydrophila) . Results showed that hydrophobic bacteria are retained in greater numbers than hydrophilic bacteria . This difference is statistically significant . Hydrophobic strains also survive longer than hydrophilic ones in sea water . Surface hydrophobicity is to be considered as a factor influencing concentration of hydrophobic pathogens by filter feeding molluscs.

Toxicol Lett, 2000 Aug 16, 116(3), 189 - 98
Toxicological evaluation by in vitro and in vivo assays of an aqueous extract prepared from Echinodorus macrophyllus leaves; da Costa Lopes L et al.; Toxicity of an aqueous extract prepared from Echinodorus macrophyllus dried leaves, a plant used in folk medicine to treat inflammation and kidney malfunctions, was estimated by different bioassays . Mutagenicity of the aqueous extract was evaluated in the Salmonella/microsome assay (TA97a, TA98, TA100 and TA102 strains), with or without metabolic activation . No mutagenic activity (lyophilized extract tested up to 50 mg/plate) could be detected to any of the tester strain . Furthermore, no cytotoxic effect has been observed when a crude extract of E . macrophyllus (up to 7.5 mg/ml) was tested on the exponential growth of hepatoma and normal kidney epithelial cells in culture . Toxicity of E . macrophyllus was also evaluated in male Swiss mice after 6 weeks of continuous ingestion of the aqueous extract in drinking water . Average daily ingested doses were 3, 23 and 297 mg/kg for a lyophilized extract, and 2200 mg/kg for a crude extract, with dose two being equivalent to the daily dose recommended to humans . At the end of the treatment, all animals revealed a deficit in final body weight ranging from 5 to 47% . Biochemical analysis of the plasma revealed some minor alterations indicating subclinical hepatic toxicity . Genotoxic effect on liver, kidney and blood cells has been also evaluated by the comet assay, being negative to liver and blood cells . However, DNA analyses of the kidney cells detected some genotoxic activity for the highest dose tested of E . macrophyllus extract, either lyophilized or crude . On the other hand, exposure dose of 23 mg/kg, equivalent to the daily dose recommended to humans, did not revealed any genotoxic effect and hence this herb seems to be safe to human organism.

Brain Res, 2000 Sep 29, 878(1-2), 127 - 35
Immunological targeting of the endothelial barrier antigen (EBA) in vivo leads to opening of the blood-brain barrier; Ghabriel MN et al.; The role of the endothelial barrier antigen (EBA) in the blood-brain barrier (BBB) of the rat is not fully understood . Pathological conditions which show BBB disruption and leakage of plasma proteins are associated with reduced EBA expression in brain endothelial cells (ECs) . However, it is not known if the reduction in EBA is the primary event or is secondary to protein extravasation . We hypothesized that immunological targeting of EBA in vivo would lead to opening of the BBB . To test this hypothesis, a monoclonal antibody (anti-EBA) was intravenously injected in anaesthetized experimental rats . Control animals received intravenous injections of phosphate-buffered saline (PBS) or non-specific antibodies (anti-human cytokeratin, anti-Salmonella bacterial antigen, or anti-pan endothelial cell antigen) . Two groups of rats were used, each included experimental and control animals . The first group was used for immunocytochemical detection of EBA in brain ECs and rat albumin in brain parenchyma . In the second group, the permeability of the BBB to horseradish peroxidase (HRP) was tested . Experimental animals, injected with anti-EBA antibody, showed extensive leakage of HRP and albumin in the grey and white matter of the brain . Immunocytochemistry of experimental brains showed that the intravenously injected anti-EBA became bound to ECs and was detected in tissue sections . Control animals did not show leakage of HRP or albumin, and EBA distribution was normal . This study demonstrated for the first time, that immunological 'neutralisation' of EBA leads to opening of the BBB, and provided direct evidence for the importance of EBA in maintaining the integrity of the BBB in the rat.

Acta Trop, 2000 Oct 23, 77(1), 101 - 9
Schistosoma mansoni: assessment of morbidity before and after control; Lambertucci JR et al.; The literature on the assessment of morbidity due to Schistosoma mansoni infection is updated . Imaging techniques such as ultrasonography, echodoppler cardiography, computerized tomography (CT scan) and magnetic resonance imaging (MRI) introduced a new perspective, and expanded our knowledge on morbidity . Three well-defined syndromes caused by schistosomiasis mansoni have been described: the stage of invasion, acute schistosomiasis (Katayama fever), and chronic schistosomiasis . Complications of the acute and chronic syndromes have also been reported: pulmonary hypertension, neuroschistosomiasis, association with Salmonella, association with Staphylococci, viral hepatitis B, glomerulonephritis . In most individuals with hepatosplenic schistosomiasis the spleen is increased in size . Hepatosplenic schistosomiasis can, however, occur without splenomegaly . The definition of hepatosplenic schistosomiasis in endemic areas as the finding of S . mansoni eggs in the stools in an individual with hepatosplenomegaly is not satisfactory anymore . Many aspects of morbidity are expected to change after schistosomiasis control . Some are expected to change quickly (worm burden, Salmonella bacteremia, hepatosplenic schistosomiasis in children) whereas others shall remain for years (pulmonary hypertension, glomerulonephritis, neuroschistosomiasis) . Intestinal schistosomiasis in individuals with low worm burdens is very difficult to diagnose and therefore laborious to control.

J AOAC Int, 2000 Jul-Aug, 83(4), 888 - 902
Equivalence of Visual Immunoprecipitate Assay (VIP) for Salmonella for the detection of motile and nonmotile Salmonella in all foods to AOAC culture method: collaborative study; Feldsine PT et al.; Six foods representative of a wide variety of processed, dried powder processed, and raw food types were analyzed by the Visual Immunoprecipitate Assay (VIP) for Salmonella and AOAC INTERNATIONAL culture method . Paired samples of each food type were simultaneously analyzed; one sample by the VIP method and one by the AOAC culture method . A total of 24 laboratories representing federal government agencies and private industry, in the United States and Canada, participated in this collaborative study . Food types were inoculated with species of Salmonella with the exception of raw ground chicken, which was naturally contaminated . No statistical differences (p < 0.05) were observed between VIP for Salmonella interpretation and the AOAC culture method for any inoculation level of any food type or naturally contaminated food . The method was adopted Official First Action status by AOAC INTERNATIONAL.

J AOAC Int, 2000 Jul-Aug, 83(4), 871 - 87
Equivalence of assurance Gold Enzyme Immunoassay for visual or instrumental detection of motile and nonmotile Salmonella in all foods to AOAC culture method: collaborative study; Feldsine PT et al.; Six foods representative of a wide variety of processed, dried powder processed, and raw food types were analyzed by the Assurance Gold Salmonella Enzyme Immunoassay (EIA) and AOAC INTERNATIONAL culture method . Paired samples of each food type were simultaneously analyzed; one sample by the Assurance method and one by the AOAC culture method . The results for Assurance method were read visually and instrumentally with a microplate reader . A total of 24 laboratories representing federal government agencies and private industry, in the United States and Canada, participated in this collaborative study . Food types were inoculated with species of Salmonella with the exception of raw ground chicken, which was naturally contaminated . No statistical differences (p < 0.05) were observed between Assurance Gold Salmonella EIA with either visual or instrumental interpretation and the AOAC culture method for any inoculation level of any food type or naturally contaminated food . The Assurance visual and instrumental options of reading sample reactions produced the same results for 1277 of the 1296 sample and controls analyzed.

Bull World Health Organ, 2000, 78(7), 945 - 6
Oral AIDS vaccine to be tested in the Republic of Uganda; Gottlieb S; PIP: Researchers at the Institute of Human Virology in Baltimore announced its plans to begin human tests of an oral vaccine for AIDS in Uganda, where 1.5 million people are already infected with the AIDS virus . The AIDS vaccine being developed by virologist Robert Gallo's team with the support of the International AIDS Vaccine Initiative is produced by an innovative approach that uses engineered Salmonella bacteria to deliver genetic material encoding vaccine DNA to human cells . Designed to be taken orally as a pill, this vaccine is inexpensive to manufacture, easy to distribute widely, and can be administered easily and safely by community health workers who would need little or no medical training . The Uganda vaccine, if it proves effective, would only combat the HIV strains prevalent in East Africa . However, segments of other HIV genes from other parts of Africa or India or Southeast Asia could be readily spliced into the Salmonella genome to target populations in those regions . The effort to develop these vaccines will be aided by the HIV Vaccine Initiative, which will focus on strengthening the capacity of poorer countries to continue to hold vaccine trials .

Korean J Intern Med, 2000 Jul, 15(2), 138 - 41
Pleural empyema due to Salmonella: a case report; Rim MS et al.; Pleuropulmonary involvement of salmonella infection is very rare and only two cases of salmonella empyema have been reported in Korea . We report the case of a 70-year-old female diabetic patient who presented with right flank pain and right lower chest pain . The chest radiographs revealed fibrostreaky and hazy density at right lower lung field and blunting of right costophrenic angle . Thoracentesis revealed turbid yellowish fluid . Salmonella group B was identified from the cultures of blood and pleural fluid . After antimicrobial therapy and repeated therapeutic thoracentesis, the patient was improved.

J Pak Med Assoc, 2000 Aug, 50(8), 282 - 4
Culture and sensitivity of Salmonella species: analysis of a two year data; Saqib A et al.; OBJECTIVE: To determine the proportion and culture/sensitivity (C/S), pattern of different species of Salmonella in blood sent for C/S in a laboratory at a tertiary care hospital . MATERIAL AND METHODS: A retrospective analysis was done on all blood samples sent for C/S to the laboratory of Ziauddin Medical University Hospital during two years period (Jan 1, 1998 to Dec 31, 1999) . 9035 blood samples were received for C/S . All blood cultures were inoculated in thioglycolate broth and incubated at 37 degrees for 7 days . Positive blood cultures were processed, colonies were identified using standard biochemical tests and antibiotic susceptibility was checked by Kirby-Bauer disc diffusion method . RESULTS: Three hundred and four (3.4%), out of 9035 blood cultures were positive for Salmonella, among them 220 (72%) were S . typhi, 82 (27%) paratyphi A or B and remaining were other species . Salmonella infection was more common in male (58%) and more prevalent in children under 10 years of age (58%) . Ampicillin, chloramphenicol, cotrimoxazole resistance was (46.5%), (39.3%) and (44.8%) respectively . CONCLUSION: Ampicillin chloramphenicol and cotrimoxazole, the first line of drugs for the treatment of infection are losing their efficacy and most of the organisms have developed resistance against these drugs.

Infect Immun, 2000 Oct, 68(10), 6041 - 3
Comparison of abilities of Salmonella enterica serovar typhimurium aroA aroD and aroA htrA mutants to act as live vectors; Roberts M et al.; We compared the ability of Salmonella enterica serovar Typhimurium SL1344 aroA aroD (BRD509) and aroA htrA (BRD807) mutants to act as live vectors for delivery of fragment C of tetanus toxin (FrgC) . FrgC was expressed in these strains from either pTETnir15 or pTEThtrA1 . BRD509FrgC(+) strains elicited approximately 2-log-higher serum anti-FrgC antibody titers than BRD807FrgC(+) strains . All mice immunized with BRD807pTEThtrA1, BRD509pTEThtrA1, and BRD509pTETnir15 (but not BRD807pTETnir15) were protected against tetanus.

Infect Immun, 2000 Oct, 68(10), 5702 - 9
Salmonella pathogenicity island 1-independent induction of apoptosis in infected macrophages by Salmonella enterica serotype typhimurium; van der Velden AW et al.; The enteric pathogen Salmonella enterica serotype Typhimurium induces apoptosis in infected macrophages . This process is rapid, specific, and depends on the type III protein secretion system encoded within Salmonella pathogenicity island 1 (SPI1) . Here, we demonstrate that serotype Typhimurium can activate programmed macrophage cell death independently of SPI1 . SPI1 independent induction of apoptosis in infected macrophages is observed as early as 12 to 13 h postinfection, even in the absence of intracellular bacterial replication . Delayed activation of programmed macrophage cell death is not observed with serotype Typhimurium strains mutated in ompR or SPI2 . Even though SPI2 mutants have a defect in intracellular proliferation, our results indicate that long-term intracellular survival and growth are not required for delayed macrophage killing per se, since Salmonella mutants that are severely defective in intracellular growth still induce delayed apoptosis . Inactivation of genes required for either rapid or delayed induction of apoptosis results in a conditional noncytotoxic phenotype, whereas simultaneous inactivation of genes required for both rapid and delayed induction of apoptosis renders serotype Typhimurium noncytotoxic under all conditions tested . Our hypothesis is that differential activation of programmed macrophage cell death by serotype Typhimurium occurs under discrete physiological conditions at distinct locations within an infected host.

Infect Immun, 2000 Oct, 68(10), 5652 - 6
Human C-reactive protein is protective against fatal Salmonella enterica serovar typhimurium infection in transgenic mice; Szalai AJ et al.; C-reactive protein (CRP) is an acute-phase protein with a well-known association with infection and other inflammatory conditions . We have shown that expression of human CRP by CRP transgenic (CRPtg) mice is protective against lethal infection by Streptococcus pneumoniae, an effect likely mediated by CRP's ability to bind to this gram-positive pathogen . In the present study we tested whether CRPtg mice are resistant to infection with Salmonella enterica serovar Typhimurium, a gram-negative pathogen that causes the murine equivalent of typhoid fever . CRPtg mice experimentally infected with a virulent Typhimurium strain lived longer and had significantly lower mortality than their non-tg littermates . The greater resistance of CRPtg mice could be attributed to significantly increased early (0 to 4 h) blood clearance of salmonellae and significantly decreased numbers of bacteria in the liver and spleen on day 7 postinfection . In addition, 14 days after infection with an avirulent Salmonella strain, the serum titer of anti-Salmonella immunoglobulin G antibodies was higher in CRPtg than non-tg mice . This study provides unequivocal evidence that CRP plays an important role in vivo in host defense against salmonellae during the early stages of infection . In addition, as the beneficial effect of CRP includes enhancement of the host's humoral immune response, CRP may also contribute indirectly to host defense during later stages of infection.

Infect Immun, 2000 Oct, 68(10), 5567 - 74
Salmonella enterica serovar typhimurium-dependent regulation of inducible nitric oxide synthase expression in macrophages by invasins SipB, SipC, and SipD and effector SopE2; Cherayil BJ et al.; When Salmonella enterica invades mammalian cells, it activates signals leading to increased expression of inflammatory mediators . One such mediator is nitric oxide (NO), which is produced under control of the enzyme inducible NO synthase (iNOS) . Induction of iNOS in response to Salmonella infection has been demonstrated, but the bacterial effector molecules that regulate expression of the enzyme have not been identified . In the study reported here, an analysis of Salmonella-dependent iNOS expression in macrophages was carried out . Wild-type Salmonella strains increased the levels of both iNOS protein and mRNA in murine macrophage cell lines in an invasion-independent fashion . Mutant strains lacking a functional pathogenicity island 1-encoded type III secretion system, as well as strains lacking the invasins SipB, SipC, and SipD, were impaired in iNOS induction . Complementation experiments indicated that all three of the invasins were required for induction of iNOS expression . These results suggested that an effector protein, translocated into macrophages via the type III secretion system in a SipB-, SipC-, and SipD-dependent manner, might be the ultimate mediator of iNOS induction . In keeping with this idea, a mutant strain deficient in SopE2, a recently described homolog of SopE, was found to be impaired in the induction of iNOS expression . These observations suggest that iNOS expression is regulated by signals activated by SopE2 (and possibly SopE) and that the role of SipB, SipC, and SipD in this process is to facilitate translocation of the relevant effector.

Infect Immun, 2000 Oct, 68(10), 5552 - 8
Regulation of cathelicidin gene expression: induction by lipopolysaccharide, interleukin-6, retinoic acid, and Salmonella enterica serovar typhimurium infection; Wu H et al.; Cathelicidins are a family of antimicrobial peptides prominent in the host defense mechanisms of several mammalian species . In addition to their antimicrobial activities, these peptides have been implicated in wound healing, angiogenesis, and other innate immune mechanisms . To investigate the regulatory mechanisms of cathelicidin gene expression, we conducted in vitro experiments evaluating the bone marrow cell expression of two porcine cathelicidins, PR-39 and protegrin, and cloned and evaluated the promoter sequence of PR-39 . In addition, we evaluated in vivo kinetics of cathelicidin gene expression in pigs during an infection with Salmonella enterica serovar Typhimurium . Lipopolysaccharide (LPS) increased PR-39 and protegrin mRNA expression, which was ameliorated by polymyxin B . Concentrations of PR-39 in supernatants from bone marrow cell cultures were increased 10-fold after LPS stimulation . Similarly, interleukin-6 (IL-6) and all-trans retinoic acid (RA) markedly induced cathelicidin gene expression . To verify the transcriptional activation of the PR-39 gene by these agents, we made a PR-39 promoter-luciferase construct containing the full-length PR-39 promoter driving luciferase gene expression and transiently transfected PK-15 epithelial cells . RA and IL-6 increased luciferase activity in PK-15 cells transfected with the PR-39 promoter-luciferase reporter . Similarly, Salmonella-challenged pigs showed increased expression of PR-39 and protegrin mRNA in bone marrow cells at 6 and 24 h postchallenge . Taken together, these findings show that bacterial products (LPS), IL-6, RA, and Salmonella infection enhance the expression of the cathelicidins, PR-39 and protegrin, in bone marrow progenitor cells, and we suggest that extrinsic modulation of this innate host defense mechanism may be possible.

Infect Immun, 2000 Oct, 68(10), 5525 - 9
High-affinity interaction between gram-negative flagellin and a cell surface polypeptide results in human monocyte activation; McDermott PF et al.; Flagella from diverse gram-negative bacteria induce tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) synthesis by human monocytes (F . Ciacci-Woolwine, P . F . McDermott, and S . B . Mizel, Infect . Immun . 67:5176-5185, 1999) . In this study, we establish that purified flagellin (FliC or FljB), the major filament protein from Salmonella enterica serovar Enteritidis, S . enterica serovar Typhimurium, and Pseudomonas aeruginosa, is an extremely potent inducer of TNF-alpha production by human monocytes and THP-1 myelomonocytic cells . Fifty percent of maximal TNF-alpha production (EC(50)) was obtained with 1.5 x 10(-11) M flagellin (0.75 ng/ml) . Mutagenesis studies revealed that the central hypervariable region of flagellin is essential for the TNF-alpha-inducing activity of the protein . Although less active than the wild-type protein, a Salmonella flagellin mutant composed of only the central hypervariable region retained substantial TNF-alpha-inducing activity at nanomolar concentrations . In contrast, the conserved amino- and carboxy-terminal regions are inactive . Mutational analysis of the hypervariable region revealed that it contains two equally active TNF-alpha-inducing domains . The ability of THP-1 cells to respond to purified flagellins is dramatically reduced by mild trypsin treatment of the cells . Taken together, our results demonstrate that the cytokine-inducing activity of flagellins from gram-negative bacteria results from the interaction of these proteins with high-affinity cell surface polypeptide receptors on monocytes.

Antimicrob Agents Chemother, 2000 Oct, 44(10), 2911 - 4
Multiple-antibiotic resistance mediated by structurally related IncL/M plasmids carrying an extended-spectrum beta-lactamase gene and a class 1 integron; Villa L et al.; A conjugative IncL/M plasmid (pSEM) conferring resistance to gentamicin, amikacin, kanamycin, sulfonamides, and expanded-spectrum cephalosporins was found in pathogenic strains of Salmonella enterica serotype Typhimurium . Resistance to aminoglycosides was encoded by a sul1-type class 1 integron (In-t3) . An extended-spectrum beta-lactamase gene, bla(SHV-5), was identified 3 . 5 kb downstream of the integrase (intI1) gene of In-t3 . Nucleotide sequence analysis of the 5.3-kb bla(SHV-5)-In-t3 region of pSEM highlighted striking similarities with IncL/M plasmids isolated from nosocomial gram-negative pathogens, conferring resistance to expanded-spectrum cephalosporins and aminoglycosides.

Antimicrob Agents Chemother, 2000 Oct, 44(10), 2858 - 60
Plasmid-mediated florfenicol resistance encoded by the floR gene in Escherichia coli isolated from cattle; Cloeckaert A et al.; A florfenicol resistance gene almost identical to floR of Salmonella enterica serovar Typhimurium DT104 was detected on 110- to 125-kb plasmids in Escherichia coli isolates of animal origin . Analysis of the floR gene flanking regions of one of the plasmids showed that they were different from those encountered in S . enterica serovar Typhimurium DT104.

Antimicrob Agents Chemother, 2000 Oct, 44(10), 2777 - 83
Animal and human multidrug-resistant, cephalosporin-resistant salmonella isolates expressing a plasmid-mediated CMY-2 AmpC beta-lactamase; Winokur PL et al.; Salmonella spp . are important food-borne pathogens that are demonstrating increasing antimicrobial resistance rates in isolates obtained from food animals and humans . In this study, 10 multidrug-resistant, cephalosporin-resistant Salmonella isolates from bovine, porcine, and human sources from a single geographic region were identified . All isolates demonstrated resistance to cephamycins and extended-spectrum cephalosporins as well as tetracycline, chloramphenicol, streptomycin, and sulfisoxazole . Molecular epidemiological analyses revealed eight distinct chromosomal DNA patterns, suggesting that clonal spread could not entirely explain the distribution of this antimicrobial resistance phenotype . However, all isolates encoded an AmpC-like beta-lactamase, CMY-2 . Eight isolates contained a large nonconjugative plasmid that could transform Escherichia coli . Transformants coexpressed cephalosporin, tetracycline, chloramphenicol, streptomycin, and sulfisoxazole resistances . Plasmid DNA revealed highly related restriction fragments though plasmids appeared to have undergone some evolution over time . Multidrug-resistant, cephalosporin-resistant Salmonella spp . present significant therapeutic problems in animal and human health care and raise further questions about the association between antimicrobial resistance, antibiotic use in animals, and transfer of multidrug-resistant Salmonella spp . between animals and man.

Mutat Res, 2000 Oct 10, 470(1), 11 - 8
Rapid analysis of base-pair substitutions induced by mutagenic drugs through their oxygen radical or epoxide derivatives; Abu-Shakra A et al.; Among the drugs that induce base-pair substitution mutations in the Salmonella reversion assay are the nitric oxide (NO)-delivery drug, diethylamine NONOate (DeaNO), and the ovarian cancer chemotherapeutic drug, treosulphan (TE) . The present study compared the mutation spectra generated by DeaNO and TE in the hisG46 strains, TA1535 and TA100, the hisG428 strain, TA102, and the six Ames II 7000 series strains . Using these strains, it was feasible to conduct rapid analysis of the type and magnitude of induced mutation without resorting to DNA amplification and sequencing . A putative hydrolysis product of TE, 1,2:3,4-diepoxybutane (DEB), and hydrogen peroxide (H(2)O(2)) were included in the study to allow for further comparisons between epoxide-induced damage and that induced by the hydroxyl radical . TE (0.93 micromole/pl) induced 16 . 8-fold-over-background reversion or a mutagenicity ratio (MR) of 16 . 8 in TA1535 . The response was weaker in TA100 (MR of 3), and negative in strain TA102 . Only two Ames II strains demonstrated sensitivity to TE, and they were TA7004 (CG:AT) and TA7005 (GC:AT) . Like TE, DeaNO (33 micromole/pl) was mutagenic in TA1535 (MR of 24.6), TA100 (MR of 5.3), TA7004 (MR of 13.7), and TA7005 (MR of 7.7), and non-mutagenic in TA102 . These results showed a preferential sensitivity to reversion of the -CCC-target in TA100 and TA1535, and a lack of sensitivity to reversion of the -TAA-target in TA102 . In addition, they elucidated the selectivity of the Ames II strains, with AT targets showing little or no sensitivity to reversion . The TE-epoxide derivative DEB was mutagenic in TA1535 and TA7004, but in contrast to TE, DEB was mutagenic in TA102 . Interestingly, TA102 was reverted by DEB and H(2)O(2) but not by TE or DeaNO . This study showed that analysis of mutations is achievable using the battery of strains listed above . The fact that DNA damage can be detected by reversion at specific bases offers a tool for understanding the mechanisms through which drugs may exert their DNA and cellular damage.

J Bacteriol, 2000 Oct, 182(19), 5606 - 10
Action of the thiamine antagonist bacimethrin on thiamine biosynthesis; Zilles JL et al.; Bacimethrin is an analog of the 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) moiety of thiamine and inhibits the growth of Salmonella enterica serovar Typhimurium on a defined medium . Two classes of mutants that had increased bacimethrin resistance were isolated and characterized . Results showed that overexpression of the thi operon or specific lesions in thiD resulted in a bacimethrin-resistant phenotype . Phenotypic analyses of the thiD mutants suggested that they had a specific defect in one of the two kinase activities associated with this gene product and, further, that ThiD and not PdxK was primarily responsible for salvage of HMP from the medium.

J Anim Sci, 2000 Sep, 78(9), 2287 - 91
Heritabilities of and genetic relationships between salmonella resistance traits in broilers; Janss LL et al.; Using experimental infections, three traits for salmonella resistance were studied: mortality, survival time (in animals that died by infection), and quantitative cecal salmonella carriage at the end of the rearing period (in animals that did not die) . In total, 548 animals were used; mortality was 29.2%, mean survival time was 5.97 d (n = 160), and the mean 10log of colony forming units per gram of cecal contents was 1.62 (n = 387) . Genetic parameters were evaluated in bivariate threshold-linear models to account for the selective measurement of survival time and cecal carriage . Heritabilities were .06 for survival time, .09 for cecal carriage, and .12 for mortality . The genetic correlation between mortality and cecal carriage was weak (.26), which suggests that these traits are largely controlled by different genes . The genetic correlation between mortality and survival time was relatively strong (-.68) . Simultaneous study of multiple traits seems to be of particular importance in judging epidemiological consequences of a possible selection for resistance . Results here indicate that selection on decreased mortality could be unfavorable for the spread of salmonella because the resulting correlated increase in survival time, implying longer shedding by infected animals, is relatively stronger than the correlated decrease in level of cecal carriage . Selection to reduce the level of cecal salmonella carriage could be done while keeping survival time constant, if so desired, because the correlation between these traits is weak (-.15).

Folia Microbiol (Praha), 1999, 44(4), 457 - 60
Cytokines in Salmonella infection; Trebichavsky I; Before the onset of specific immune response, the host defence against Salmonella infection is regulated by cytokines characteristic for immunity to intracellular bacteria . Cytokine response to non-typhoidal Salmonellae is described.

Epidemiol Infect, 2000 Jun, 124(3), 383 - 92
Serovar specific risk factors and clinical features of Salmonella enterica ssp . enterica serovar Enteritidis: a study in South-West Germany; Kist MJ et al.; Human salmonellosis in Germany has been an increasing problem since the 1980s, with a peak of 195,000 reported cases in 1992 . During the peak years, isolates of Salmonella Enteritidis (SE) predominated by far over other salmonella serovars (NSE) (80 vs . 20%) . In a comparison of the clinical characteristics of 790 persons infected with SE to 175 persons infected with NSE, watery diarrhoea (OR 1.7) and high grade (> 39 degrees C) fever (OR 1.8) were independently associated with SE infection . When comparing possible risk factors for acquiring salmonella infection among patients with SE compared to those with NSE, consumption of raw eggs (OR 4.4; P = 0.0006) was the most significant alimentary risk factor for SE infection, while travel outside Europe was negatively associated with SE infection (OR 0.08; P = 0.0001) . When comparing all patients with salmonella infection, regardless of serovar, with healthy controls, consumption of raw eggs (OR 30.3; P = 0.001), of raw or undercooked eggs (OR 1.9; P = 0.003), or having puppies, kittens or turtles (OR 6.8; P = 0.002), were risk factors for salmonellosis.

Epidemiol Infect, 2000 Jun, 124(3), 375 - 82
Grouping of Salmonella enterica serotype Montevideo strains by ribotyping and IS200 profiling; Old DC et al.; One-hundred and twenty-one isolates of Salmonella enterica serotype Montevideo, representing different biotypes and incidents of infection detected in the UK between 1977 and 1995, were analysed by EcoRI ribotyping, PvuII ribotyping and IS200 fingerprinting . Among the isolates examined, 7 EcoRI ribotypes, 5 PvuII ribotypes and 55 IS200 profile types were recognized and 4 arbitrary groups defined . All 33 isolates of biotype 2d belonged to EcoRI/PvuII ribotype 1/1 and IS200 lineage A and comprised Group I . The other 88 isolates of biotype 10di and its variants were assigned to Groups II-IV . All 27 isolates in Group II were of EcoRI/PvuII ribotype 2/2 and IS200 lineage B . Among the 43 isolates in Group III, 42 of which were of EcoRI/PvuII ribotype 3/3, IS200 analysis identified 38 profiles in lineages C-I . Six EcoRI/PvuII ribotypes and 8 IS200 profiles, mostly in lineages C-E, were recognized among the 18 isolates in Group IV . The combined use of biotyping and ribotyping, and to some extent IS200 profiling, has enhanced our understanding of the clonal structure of serotype Montevideo and provides a basis for further study.

Epidemiol Infect, 2000 Jun, 124(3), 365 - 73
A model for evaluating intervention strategies to control salmonella in the poultry meat production chain; Nauta MJ et al.; A model of the transmission of salmonella through the poultry meat production chain is developed, to predict the effects of intervention strategies for salmonella control . The model first describes the situation before intervention in terms of salmonella prevalences at flock level and some transmission parameters . After single control measures are translated into effects on these transmission parameters, the effects of sets of control measures (intervention strategies), can be calculated with the model . As research data are lacking, the model input parameters were derived from expert opinion . As an example, the effects of two intervention strategies proposed for the Dutch poultry industry are predicted . A sensitivity analysis is performed to indicate where the most effective control measures may be expected . Additionally, the reliability of the model predictions is studied by an uncertainty analysis . The use of the model as a tool for policy makers deciding about salmonella control strategies is discussed.

Microbiol Immunol, 2000, 44(7), 577 - 83
Clinical and bacteriological profiles of patients with typhoid fever treated during 1975-1998 in the Tokyo Metropolitan Komagome Hospital; Hoshino Y et al.; Patients with typhoid fever presenting to the Tokyo Metropolitan Komagome Hospital during the period 1975-1998 were retrospectively investigated . All cases were diagnosed by a positive culture for Salmonella typhi in either of their clinical specimens . Of the total number of 130 patients, 57% contracted the disease abroad; this population increased in later years as the total numbers of cases decreased . The period from disease onset to diagnosis averaged 14 days with 20% of the cases requiring over three weeks to establish a diagnosis . As for symptomatology relative bradycardia was seen in less than half of the cases, and rose spots or splenomegaly in less than one third . A positive blood culture was the most frequent test establishing the diagnosis followed by a positive stool culture . Intestinal bleeding was recognized in as many as 35 cases (27%) and even intestinal perforation occurred in two cases (1.5%) . Chloramphenicol was most commonly employed during the early study period, however, during the late period it was replaced by fluoroquinolones . The clinical cure rate was 98% with regimens that include fluoroquinolones/quinolone; however it was 87% with the other antimicrobial regimens . Bacteriological relapse occurred in 25% of the non-fluoroquinolone group while only in 2.0% in the fluoroquinolone/quinolone group . Four strains of Salmonella typhi that were multi-resistant to chloramphenicol, ampicillin and cotrimoxazole were isolated in travelers from Asia . Early diagnosis by appropriate bacteriological examination regardless of classical symptomatology should be stressed and the use of fluoroquinolones is warranted in the treatment of typhoid fever.

J Immunol, 2000 Sep 15, 165(6), 3324 - 32
Salmonella infection does not increase expression and activity of the high affinity IL-12 receptor; Elhofy A et al.; Expression of high affinity IL-12 receptors is required for IL-12-mediated IFN-gamma production . Activation of this pathway has been shown to be critical in generating optimal cell-mediated immunity . Therefore, increased IL-12 receptor expression might be expected in the host response after infection by an intracellular bacterial pathogen . In the present study, we have made the surprising discovery that infection with Salmonella results in an early reduction of high affinity IL-12 receptor expression and activation . After oral inoculation with Salmonella, the level of mRNA expression encoding IL-12 receptor beta2 (IL-12Rbeta2) subunit was diminished 12 h postinfection in the mesenteric lymph nodes and subsequently in the spleen . Furthermore, decreased IL-12Rbeta2 mRNA expression was observed in CD4+ T lymphocytes isolated from the mesenteric lymph nodes and spleens of infected mice . Attenuated IL-12Rbeta2 mRNA expression correlated with reduced receptor signaling, as demonstrated by reduced IL-12-induced STAT4 phosphorylation in enriched T lymphocytes isolated from the mesenteric lymph nodes and spleens of Salmonella-infected mice . These in vivo results were substantiated with an in vitro model system . In this model system, T lymphocytes cocultured with Salmonella-infected macrophages expressed less IL-12Rbeta2 mRNA . The cocultured T cells were also less responsive to IL-12 as assessed by reduced phosphorylation of STAT4 and limited IFN-gamma secretion . Together, these studies suggest that Salmonella can limit an optimal host immune response by reducing the expression and activity of high affinity IL-12 receptors.

J Immunol, 2000 Sep 15, 165(6), 2955 - 61
Somatostatin through its specific receptor inhibits spontaneous and TNF-alpha- and bacteria-induced IL-8 and IL-1 beta secretion from intestinal epithelial cells; Chowers Y et al.; Intestinal epithelial cells secrete proinflammatory cytokines and chemokines that are crucial in mucosal defense . However, this secretion must be tightly regulated, because uncontrolled secretion of proinflammatory mediators may lead to chronic inflammation and mucosal damage . The aim of this study was to determine whether somatostatin, secreted within the intestinal mucosa, regulates secretion of cytokines from intestinal epithelial cells . The spontaneous as well as TNF-alpha- and Salmonella-induced secretion of IL-8 and IL-1beta derived from intestinal cell lines Caco-2 and HT-29 was measured after treatment with somatostatin or its synthetic analogue, octreotide . Somatostatin, at physiological nanomolar concentrations, markedly inhibited the spontaneous and TNF-alpha-induced secretion of IL-8 and IL-1beta . This inhibition was dose dependent, reaching >90% blockage at 3 nM . Furthermore, somatostatin completely abrogated the increased secretion of IL-8 and IL-1beta after invasion by Salmonella . Octreotide, which mainly stimulates somatostatin receptor subtypes 2 and 5, affected the secretion of IL-8 and IL-1beta similarly, and the somatostatin antagonist cyclo-somatostatin completely blocked the somatostatin- and octreotide-induced inhibitory effects . This inhibition was correlated to a reduction of the mRNA concentrations of IL-8 and IL-1beta . No effect was noted regarding cell viability . These results indicate that somatostatin, by directly interacting with its specific receptors that are expressed on intestinal epithelial cells, down-regulates proinflammatory mediator secretion by a mechanism involving the regulation of transcription . These findings suggest that somatostatin plays an active role in regulating the mucosal inflammatory response of intestinal epithelial cells after physiological and pathophysiological stimulations such as bacterial invasion.

Enferm Infecc Microbiol Clin, 2000 May, 18(5), 219 - 22
{Extra-intestinal infections caused by non-typhi Salmonella serotypes . 9 yrs' experience}; Ruiz M et al.; BACKGROUND: The most characteristic finding in non typhoid Salmonella serotype infection is acute gastroenteritis which is usually benign and self-limiting . However, more serious extraintestinal findings, such as bacteraemia and focal infections localized to any organ may appear . PATIENTS AND METHODS: The objective of this article is to describe the most important characteristics of the extraintestinal infections due to non typhoid Salmonella serotypes observed in our hospital between December 1991 and August 1999 . To do so, we reviewed the clinical histories of patients in which extraintestinal non typhoid Salmonella serotypes was isolated, applying a clinicomicrobiological protocol . RESULTS: Salmonella enterica was isolated on 1,543 occasions, of which 25 (1.6%) were Salmonella serotype Typhi and 1,518 (98.3%) non typhoid serotypes . Of the patients with non typhoid serotypes infections, 27 had extraintestinal infection (1.8%) . The most frequently isolated was the serotype typhimurium (50% of cases) followed by enteritidis (26% of cases) and hadar (7.1% of cases) . Regarding the clinical picture, bacteraemias secondary to gastroenteritis and focal infections occurred with the same frequency (35.7%); the remaining were primary bacteraemias . Eight patients were under 10 years of age and 15 patients were over 60 . In 57.1% of the patients there was underlying disease . CONCLUSIONS: Extraintestinal non typhoid Salmonella serotypes infections make up 1.8% of all salmonellosis and most of them occur in childhood or in the elderly . Transitory bacteraemias in the context of acute gastroenteritis occur mainly in children . The greatest risk of acquiring focal infections is associated with the existence of underlying illness or immunodepression.

Microbiology, 2000 Sep, 146 ( Pt 9), 2291 - 307
Genetic variation of dTDP-L-rhamnose pathway genes in Salmonella enterica; Li Q et al.; The genetic variation in the dTDP-L-rhamnose pathway gene set (rmlB, rmlD, rmlA, rmlC) in Salmonella enterica was examined after sequencing the four genes from 11 rml-containing gene clusters encoding seven O antigens, and a 903 bp rmlB segment from another 23 strains representing the seven subspecies . There was considerable sequence variation and strong polarity in the nature and level of variation among rml genes . The 5' end of the rml gene set, including rmlB, rmlD and most of rmlA, is in general subspecies specific . In contrast, the 3' end, including part of rmlA and all of rmlC, is O antigen specific . The G+C content of the 3' end is lower than that of the 5' end . The variation in the 3' end of the gene set is much greater than that of the 5' end . It is apparent that the rml gene set of S . enterica includes genes with two different evolutionary histories . In addition, there has been extensive recombination in the gene set, probably related to O antigen transfer between subspecies . These findings provide evidence for the lateral transfer of O antigen genes between species and among subspecies of S . enterica . The results have also shown that conserved genes at the end of an O antigen gene cluster play a major role in mediating exchange of the central serogroup-specific regions.

Eur J Cardiothorac Surg, 2000 Sep, 18(3), 360 - 2
Ventriculotomy and resection for left ventricular thrombus infection with Salmonella; Mathieu P et al.; We report the case of a patient with a left ventricular thrombus infected by Salmonella . The diagnosis was suspected from a gallium scan demonstrating an intense activity in the lower left parasternal area . A transesophageal echocardiogram confirmed a calcified left ventricular aneurysm with a mural thrombus containing pus and heterogeneous material . The patient underwent a successful left ventricular aneurysmectomy, thrombectomy and endocardial resection under cardiopulmonary bypass which brought the infection under control.

Mol Microbiol, 2000 Aug, 37(4), 727 - 39
Membrane fusion activity of purified SipB, a Salmonella surface protein essential for mammalian cell invasion; Hayward RD et al.; An early event in Salmonella infection is the invasion of non-phagocytic intestinal epithelial cells . The pathogen is taken up by macropinocytosis, induced by contact-dependent delivery of bacterial proteins that subvert signalling pathways and promote cytoskeletal rearrangement . SipB, a Salmonella protein required for delivery and invasion, was shown to localize to the cell surface of bacteria invading mammalian target cells and to fractionate with outer membrane proteins . To investigate the properties of SipB, we purified the native full-length protein following expression in recombinant Escherichia coli . Purified SipB assembled into hexamers via an N-terminal protease-resistant domain predicted to form a trimeric coiled coil, reminiscent of viral envelope proteins that direct homotypic membrane fusion . The SipB protein integrated into both mammalian cell membranes and phospholipid vesicles without disturbing bilayer integrity, and it induced liposomal fusion that was optimal at neutral pH and influenced by membrane lipid composition . SipB directed heterotypic fusion, allowing delivery of contents from E . coli-derived liposomes into the cytosol of living mammalian cells.

Lett Appl Microbiol, 2000 Sep, 31(3), 233 - 7
Transient sensitivity to nisin in cold-shocked Gram negatives; Boziaris IS et al.; Rapid chilling in the presence of nisin caused a dose-dependent reduction in the populations of several Gram-negative bacteria, despite the fact that appreciable structural injury to the outer membrane was not detected . Pseudomonas aeruginosa was most affected, followed by Pseudomonas fragi, Salmonella enteritidis PT4, PT7 and Escherichia coli, respectively . Addition of nisin after the chilling treatment had no effect . The results are ascribed to a transient susceptibility caused by phase changes in the lipids associated with the outer membrane, which are rapidly reversed when the cells return to higher temperatures . Combinations of chilling shock, nisin and EDTA gave much lower reductions of Salmonella and Pseudomonas on chicken skin in comparison with broths . This is attributed to a buffering of the temperature shock experienced by adherent bacteria and binding of the nisin by food particles.

Lett Appl Microbiol, 2000 Aug, 31(2), 143 - 8
Survival of Salmonella hadar after washing disinfection of minimally processed spinach; Pirovani ME et al.; Washing disinfection with chlorine is widely used to reduce the initial microbiological load during the preparation of minimally processed vegetables . The effects of initial concentration of chlorine, time and the liquid volume:produce weight ratio on the reduction of Salmonella counts on inoculated spinach were evaluated using response surface methodology . Initial chlorine concentration, time and the interaction between them had a significant effect on reduction of Salmonella populations . However, the liquid volume:produce weight ratio did not have significant effects . The highest Salmonella reduction was around 1.2-1.4 log at 125 ppm during 8 min regardless of the water:produce ratio . According to the results, chlorination reduced Salmonella hadar population, but the complete elimination from the produce was not achieved.

Lett Appl Microbiol, 2000 Aug, 31(2), 115 - 7
A Fusobacterium mortiferum strain produces a bacteriocin-like substance(s) inhibiting Salmonella enteritidis; Portrait V et al.; Seven strictly anaerobic strains showing anti-Salmonella enteritidis activity were isolated from poultry caecal contents . Among them, the most inhibitory one, a strain of Fusobacterium mortiferum, called FM1025, was selected . Biochemical tests, showing the proteinaceous structure of the antagonist(s) produced, indicated that the strain Fus . mortiferum FM1025 synthesized (a) bacteriocin-like compound(s) active against Salm . enteritidis . Among the other strains tested, both Gram-negative and Gram-positive bacteria were inhibited . These preliminary results suggested the important role of the Fusobacterium strains against pathogenic bacteria among the intestinal flora.

Lett Appl Microbiol, 2000 Aug, 31(2), 105 - 9
Development of a multiplex PCR detection of Salmonella spp . and Shigella spp . in mussels; Vantarakis A et al.; Multiplex PCR amplification of invA and virA genes was developed enabling simultaneous detection in mussels of Salmonella spp . and Shigella spp., respectively . Simultaneous amplification of products of 215 and 275 bp was obtained either by using mixtures of individual strains of Sh . dysenteriae and Salm . typhimurium or spiked contaminated mussels with both bacteria . In the case of the mussels, 10-100 cells of Salmonella spp . and Shigella per millilitre of homogenate were detected by the multiplex PCR following a pre-enrichment step to increase sensitivity and to ensure that detection was based on the presence of cultivable bacteria . Also, the sensitivity and specificity of this method was evaluated . Multiplex PCR amplification was shown to be an effective, sensitive and rapid method for the simultaneous detection of pathogens in mussels.

Med J Malaysia, 1999 Mar, 54(1), 120 - 4
Disseminated histoplasmosis in a non-immunocompromised child; Hasliza M et al.; We describe a 2 year-old non-immunocompromised girl with disseminated histoplasmosis who presented with a 2-month history of fever and bloody diarrhoea . On presentation, she was severely wasted and anaemic . There were gross hepatosplenomegaly and multiple lymphadenopathy . A septic screen was negative . A subsequent stool culture isolated Salmonella enteriditis . Serial Widal-Weil Felix (WWF) titres showed serological response after 2 weeks of Ceftriaxone . However, she continued to have spiking fever, bloody diarrhoea and weight loss . She developed pancytopaenia and disseminated intravascular coagulation . A bone marrow aspirate and trephine, and lymph node biopsy showed the presence of Histoplasma capsulatum, confirmed by Gomori-Methenamine Silver staining . She responded to intravenous amphotericin B followed by fluconazole (intravenous then oral) for 6 months after discharge . Human Immunodeficiency Virus screening tests were negative . Complement and immunoglobulin levels were normal . T and B enumeration tests showed gross leucopaenia with very low T cell function with defective phagocytic function . A repeat T and B cell enumeration test and phagocytic function tests done 3 months later were normal.

Aliment Pharmacol Ther, 2000 Sep, 14(9), 1107 - 18
Review article: Helicobacter pylori vaccines-the current status; Sutton P et al.; In this review, we take a look at the current status in the development of a vaccine against the human pathogenic bacterium, Helicobacter pylori, a major aetiological factor in peptic ulcer disease and gastric adenocarcinoma . Various animal models are now in use from mice infected with H . pylori, through gnotobiotic pigs and primates to ferrets naturally infected with their own Helicobacter, H . mustelae . A significant problem remains the requirement for a suitable mucosal adjuvant . Detoxification or the use of low doses of adjuvants already available may provide a solution and new immune stimulating compounds have been tested with some success . New approaches include the delivery of Helicobacter antigens by DNA immunization, microparticles or live vectors such as attenuated salmonella and the examination of alternative routes of vaccine administration . The phenomenon of post-immunization gastritis and improvements in vaccine efficacy are also discussed . A major area of interest is the mechanism by which immunization actually influences Helicobacter colonization . This remains a mystery: antibodies appear to be unimportant whereas CD4+ T-cells essential . Finally, a viewpoint is given on whom should be immunized when a final vaccine becomes available.

J Clin Microbiol, 2000 Sep, 38(9), 3484 - 8
Identification of DT104 and U302 phage types among Salmonella enterica serotype typhimurium isolates by PCR; Pritchett LC et al.; A DNA sequence was identified in isolates of Salmonella enterica serotype Typhimurium definitive type 104 (DT104) . The PCR amplification of an internal segment of this sequence identified DT104 and the closely related U302 phage type among 146 isolates of S . enterica serotype Typhimurium tested, thus providing a tool for rapid identification of DT104 and related isolates.

J Clin Microbiol, 2000 Sep, 38(9), 3429 - 35
Automated 5' nuclease PCR assay for identification of Salmonella enterica; Hoorfar J et al.; A simple and ready-to-go test based on a 5' nuclease (TaqMan) PCR technique was developed for identification of presumptive Salmonella enterica isolates . The results were compared with those of conventional methods . The TaqMan assay was evaluated for its ability to accurately detect 210 S . enterica isolates, including 100 problematic "rough" isolates . An internal positive control was designed to use the same Salmonella primers for amplification of a spiked nonrelevant template (116 bp) in the sample tube . The PCR test correctly identified all the Salmonella strains by resulting in positive end-point fluorescence (FAM) signals for the samples and positive control (TET) signals (relative sensitivity {DeltaRn}, >0 . 6) . The diagnostic specificity of the method was assessed using 120 non-Salmonella strains, which all resulted in negative FAM signals (DeltaRn, < or =0.5) . All 100 rough Salmonella strains tested resulted in positive FAM and TET signals . In addition, it was found that the complete PCR mixture, predispensed in microwell plates, could be stored for up to 3 months at -20 degrees C . Thus, the diagnostic TaqMan assay developed can be a useful and simple alternative method for identification of Salmonella, particularly in large reference laboratories.

Rev Latinoam Microbiol, 1999 Apr-Jun, 41(2), 77 - 82
{Serotypes of Salmonella isolated from the Luján River, Argentina}; Anselmo RJ et al.; In this work, the serotypes of Salmonella genus polluting the waters of Lujan River, situated in the north east of the province of Buenos Aires, Argentina, were studied . A total of 690 samples of water were collected and analysed from February 1988 through December 1989, at three different sites . They were obtained according to the Moore technique and then preenriched in buffered peptone water and enriched in Rappaport-Vassiliadis Soya peptone broth was carried out . The isolations were realised in brilliant green-desoxycholate agar and bismuth sulphite agar and the presumptive colonies to be Salmonella were tested by the standard biochemical identification . Salmonella spp . was isolated in 434 samples (62.9%) . The predominant serotype was S . Anatum, followed in a decreasing order by S . Montevideo, S . Newport and S . Bredeney . A large amount of serotypes that are isolated with very low frequency and very rarely in other hidric courses in the country were: S . Westhampton, S . Poona and S . Saintpaul were found.

Rev Inst Med Trop Sao Paulo, 2000 Jul-Aug, 42(4), 201 - 7
Epidemiological analysis of bacterial strains involved in hospital infection in a university hospital from Brazil; Moraes BA et al.; Hospital infections cause an increase in morbidity and mortality of hospitalized patients with significant rise in hospital costs . The aim of this work was an epidemiological analysis of hospital infection cases occurred in a public University Hospital in Rio de Janeiro . Hence, 238 strains were isolated from 14 different clinical materials of 166 patients hospitalized in the period between August 1995 and July 1997 . The average age of the patients was 33.4 years, 72.9% used antimicrobials before having a positive culture . The most common risk conditions were surgery (19.3%), positive HIV or AIDS (18.1%) and lung disease (16.9%) . 24 different bacterial species were identified, S . aureus (21%) and P . aeruginosa (18.5%) were predominant . Among 50 S . aureus isolated strains 36% were classified as MRSA (Methicillin Resistant S . aureus) . The Gram negative bacteria presented high resistance to aminoglycosides and cephalosporins . A diarrhea outbreak, detected in high-risk neonatology ward, was caused by Salmonella serovar Infantis strain, with high antimicrobial resistance and a plasmid of high molecular weight (98Mda) containing virulence genes and positive for R factor.

Science, 2000 Sep 1, 289(5484), 1560 - 3
Prokaryotic regulation of epithelial responses by inhibition of IkappaB-alpha ubiquitination; Neish AS et al.; Epithelia of the vertebrate intestinal tract characteristically maintain an inflammatory hyporesponsiveness toward the lumenal prokaryotic microflora . We report the identification of enteric organisms (nonvirulent Salmonella strains) whose direct interaction with model human epithelia attenuate synthesis of inflammatory effector molecules elicited by diverse proinflammatory stimuli . This immunosuppressive effect involves inhibition of the inhibitor kappaB/nuclear factor kappaB (IkappaB/NF-kappaB) pathway by blockade of IkappaB-alpha degradation, which prevents subsequent nuclear translocation of active NF-kappaB dimer . Although phosphorylation of IkappaB-alpha occurs, subsequent polyubiquitination necessary for regulated IkappaB-alpha degradation is completely abrogated . These data suggest that prokaryotic determinants could be responsible for the unique tolerance of the gastrointestinal mucosa to proinflammatory stimuli.

Med J Malaysia, 1998 Mar, 53(1), 109 - 11
Typhoid thyroiditis; Jasmi AY et al.; Acute suppurative thyroiditis in a 62 year old lady with enteric fever is reported . Plain radiography of the neck showed a distinct localised abscess cavity with air fluid level . A rare causative agent Salmonella typhi was isolated . Needle aspiration and antibiotics resulted in complete recovery.

Med J Malaysia, 1997 Jun, 52(2), 178 - 80
Primary repair with in-situ interposition graft for infrarenal mycotic aortic pseudoaneurysm; Adeeb SJ et al.; This is a case report of a pseudoaneurysm due to Salmonella aortitis in a 52 year old man . The condition is rare and represents one of the few cases reported in Malaysia . The diagnosis was made preoperatively by ultrasonography and computed tomography . This was confirmed at surgery where there was a 3 cm defect at the posterior wall of the aorta at L2/3 level . The aneurysmal sac extended to the retrocrural space at the 12th vertebra level cranially on the right side to the lower border of the 3rd lumbar vertebra caudally . It had a smooth fibrous wall and contained a mixture of organised haematoma and pus . At operation the aneurysm was excised, the affected region was carefully debrided and the aorta grafted with an in-situ in-lay graft . Antibiotic therapy was instituted until clinical response was evident, leukocytosis was reduced and blood culture was negative . However 4 months after surgery, the patient returned in irreversible shock and succumbed to disseminated intravascular coagulation secondary to massive upper gastrointestinal haemorrhage from an aortoduodenal fistula.

FEMS Immunol Med Microbiol, 2000 Sep, 29(1), 9 - 13
Genotypes of multidrug-resistant Salmonella enterica serotype typhimurium from two regions of Kenya; Kariuki S et al.; A combination of phage typing and pulsed-field gel electrophoresis of Xbal-digested chromosomal DNA has been used to study the epidemiological relationships of multidrug-resistant Salmonella enterica serotype typhimurium from Nairobi (64 isolates) and Kilifi (40 isolates) collected over the period 1994-1997 . Isolates from Nairobi belonged to 11 definitive phage types (DTs) encompassing eight different PFGE patterns . In contrast, isolates from Kilifi were mainly DT 56 (60%) and all fell into a single PFGE pattern . The remaining isolates did not conform to a recognisable phage type . We conclude that multidrug-resistant S . typhimurium infections from Nairobi were caused by multiple strains while those from Kilifi were likely to be from a microepidemic caused by a single clone.

Appl Environ Microbiol, 2000 Sep, 66(9), 4128 - 30
Resuscitation by ferrioxamine E of stressed Salmonella enterica serovar typhimurium from soil and water microcosms; Reissbrodt R et al.; Storage of Salmonella enterica serovar Typhimurium strains in soil and water microcosms resulted in loss of culturability on standard plating media . Prior incubation in buffered peptone water supplemented with ferrioxamine E markedly extended the time that bacteria were recoverable by plating, except in the case of mutants deficient in ferrioxamine E uptake.

Appl Environ Microbiol, 2000 Sep, 66(9), 4124 - 7
Murine monoclonal antibodies specific for lipopolysaccharide of Escherichia coli O26 and O111; Rivera-Betancourt M et al.; Monoclonal antibody (MAb) 12F5 reacted with 35 Escherichia coli O26 isolates and cross-reacted with 1 of 365 non-E . coli O26 isolates . MAb 15C4 reacted with 30 E . coli O111 strains and 8 Salmonella O35 strains (possessing identical O antigen) but not with 362 other bacterial strains . Lipopolysaccharide immunoblots confirmed MAb O-antigen specificity.

Appl Environ Microbiol, 2000 Sep, 66(9), 3939 - 44
Engineering hydrogen sulfide production and cadmium removal by expression of the thiosulfate reductase gene (phsABC) from Salmonella enterica serovar typhimurium in Escherichia coli; Bang SW et al.; The thiosulfate reductase gene (phsABC) from Salmonella enterica serovar Typhimurium was expressed in Escherichia coli to overproduce hydrogen sulfide from thiosulfate for heavy metal removal (or precipitation) . A 5.1-kb DNA fragment containing phsABC was inserted into the pMB1-based, high-copy, isopropyl-beta-D-thiogalactopyranoside-inducible expression vector pTrc99A and the RK2-based, medium-copy, m-toluate-inducible expression vector pJB866, resulting in plasmids pSB74 and pSB77 . A 3 . 7-kb DNA fragment, excluding putative promoter and regulatory regions, was inserted into the same vectors, making plasmids pSB103 and pSB107 . E . coli DH5alpha strains harboring the phsABC constructs showed higher thiosulfate reductase activity and produced significantly more sulfide than the control strains under both aerobic and anaerobic conditions . Among the four phsABC constructs, E . coli DH5alpha (pSB74) produced thiosulfate reductase at the highest level and removed the most cadmium from solution under anaerobic conditions: 98% of all concentrations up to 150 microM and 91% of 200 microM . In contrast, a negative control did not produce any measurable sulfide and removed very little cadmium from solution . Energy-dispersive X-ray spectroscopy revealed that the metal removed from solution precipitated as a complex of cadmium and sulfur, most likely cadmium sulfide.

Trop Med Int Health, 2000 Jul, 5(7), 503 - 6
Salmonella enteritidis diarrhoea in Harare, Zimbabwe; Simango C et al.; The study was conducted to determine the prevalence of Salmonella enteritidis diarrhoea in an urban area in Zimbabwe . Stool specimens from people of all ages presenting at primary level health centres in Harare were investigated for S . enteritidis and other bacterial and parasitic enteric pathogens . The first 46 S . enteritidis isolates were phage-typed, and all isolates were tested for susceptibility to ampicillin (10 microg), chloramphenicol (30 microg), cotrimoxazole (25 microg), tetracycline (30 microg), gentamicin (10 microg), nalidixic acid (30 microg), ciprofloxacin (5 microg) and ceftriaxone (30 microg) . S . enteritidis was isolated in 74 (1.8%) of 4155 stool specimens which represented 30.7% of all Salmonella species isolated . The most common S . enteritidis phage type was 4 (78.3%) followed by 7, 9 and 23 (8.7%, 2.2%, 2.2%, respectively) All S . enteritidis isolates were sensitive to gentamicin, ciprofloxacin and ceftriaxone . Less than 10% of the isolates were resistant to the other antimicrobials except ampicillin, to which 13.5% were resistant . One isolate was resistant to ampicillin, chloramphenicol, cotrimoxazole and nalidixic acid.

Circulation, 2000 Aug 29, 102(9), 994 - 9
Acute systemic inflammation impairs endothelium-dependent dilatation in humans; Hingorani AD et al.; BACKGROUND: We tested the hypothesis that endothelial dysfunction underlies the association between an acute inflammatory episode and the transiently increased risk of a cardiovascular event by examining the effects of an experimental inflammatory stimulus on endothelium-dependent vasodilation . METHODS AND RESULTS: Salmonella typhi vaccine was used to generate a systemic inflammatory response in healthy volunteers . In 12 subjects, dilatation of the brachial artery to flow and to sublingual nitroglycerin (NTG) was recorded (conduit vessel response), and in 6 subjects, venous occlusion plethysmography was used to measure forearm blood flow during intrabrachial infusion of the endothelium-dependent dilators acetylcholine (ACh) and bradykinin (BK) and the endothelium-independent dilators NTG and verapamil (resistance vessel response) . Responses were assessed 16 hours before and 8 and 32 hours after vaccination . Vaccination resulted in elevations in white cell count and serum levels of interleukin-6 and interleukin-1 receptor antagonist . Eight hours after vaccination, resistance vessel responses to BK (P:=0.0099) and ACh (P:=0.0414) were markedly attenuated, and brachial artery flow-mediated dilatation was depressed . Resistance vessel responses to verapamil and NTG were unchanged, as was the conduit vessel response to NTG . Thirty-two hours after vaccination, resistance vessel responses to BK and ACh had returned to normal . CONCLUSIONS: S typhi vaccine generates a mild inflammatory reaction associated with temporary but profound dysfunction of the arterial endothelium in both resistance and conduit vessels to both physical and pharmacological dilator stimuli . This finding might explain the association between infection and inflammation and the enhanced risk of an acute cardiovascular event.

J Bacteriol, 2000 Sep, 182(18), 5218 - 24
The flagellar filament of Rhodobacter sphaeroides: pH-induced polymorphic transitions and analysis of the fliC gene; Shah DS et al.; Flagellar motility in Rhodobacter sphaeroides is notably different from that in other bacteria . R . sphaeroides moves in a series of runs and stops produced by the intermittent rotation of the flagellar motor . R . sphaeroides has a single, plain filament whose conformation changes according to flagellar motor activity . Conformations adopted during swimming include coiled, helical, and apparently straight forms . This range of morphological transitions is larger than that in other bacteria, where filaments alternate between left- and right-handed helical forms . The polymorphic ability of isolated R . sphaeroides filaments was tested in vitro by varying pH and ionic strength . The isolated filaments could form open-coiled, straight, normal, or curly conformations . The range of transitions made by the R . sphaeroides filament differs from that reported for Salmonella enterica serovar Typhimurium . The sequence of the R . sphaeroides fliC gene, which encodes the flagellin protein, was determined . The gene appears to be controlled by a sigma(28)-dependent promoter . It encodes a predicted peptide of 493 amino acids . Serovar Typhimurium mutants with altered polymorphic ability usually have amino acid changes at the terminal portions of flagellin or a deletion in the central region . There are no obvious major differences in the central regions to explain the difference in polymorphic ability . In serovar Typhimurium filaments, the termini of flagellin monomers have a coiled-coil conformation . The termini of R . sphaeroides flagellin are predicted to have a lower probability of coiled coils than are those of serovar Typhimurium flagellin . This may be one reason for the differences in polymorphic ability between the two filaments.

J Bacteriol, 2000 Sep, 182(18), 5180 - 7
Lesions in gshA (Encoding gamma-L-glutamyl-L-cysteine synthetase) prevent aerobic synthesis of thiamine in Salmonella enterica serovar typhimurium LT2; Gralnick J et al.; Thiamine pyrophosphate is an essential cofactor that is synthesized de novo in Salmonella enterica serovar Typhimurium and other bacteria . In addition to genes encoding enzymes in the biosynthetic pathway, mutations in other metabolic loci have been shown to prevent thiamine synthesis . The latter loci identify the integration of the thiamine biosynthetic pathway with other metabolic processes and can be uncovered when thiamine biosynthesis is challenged . Mutations in gshA, encoding gamma-L-glutamyl-L-cysteine synthetase, prevent the synthesis of glutathione, the major free thiol in the cell, and are shown here to result in a thiamine auxotrophy in some of the strains tested, including S . enterica LT2 . Phenotypic characterization of the gshA mutants indicated they were similar enough to apbC and apbE mutants to warrant the definition of a class of mutants unified by (i) a requirement for both the hydroxymethyl pyrimidine (HMP) and thiazole (THZ) moiety of thiamine, (ii) the ability of L-tryosine to satisfy the THZ requirement, (iii) suppression of the thiamine requirement by anaerobic growth, and (iv) suppression by a second-site mutation at a single locus . Genetic data indicated that a defective ThiH generates the THZ requirement in these strains, and we suggest this defect is due to a reduced ability to repair a critical {Fe-S} cluster.

J Bacteriol, 2000 Sep, 182(18), 5046 - 51
A hydrogen peroxide-forming NADH oxidase that functions as an alkyl hydroperoxide reductase in Amphibacillus xylanus; Niimura Y et al.; The Amphibacillus xylanus NADH oxidase, which catalyzes the reduction of oxygen to hydrogen peroxide with beta-NADH, can also reduce hydrogen peroxide to water in the presence of free flavin adenine dinucleotide (FAD) or the small disulfide-containing Salmonella enterica AhpC protein . The enzyme has two disulfide bonds, Cys128-Cys131 and Cys337-Cys340, which can act as redox centers in addition to the enzyme-bound FAD (K . Ohnishi, Y . Niimura, M . Hidaka, H . Masaki, H . Suzuki, T . Uozumi, and T . Nishino, J . Biol . Chem . 270:5812-5817, 1995) . The NADH-FAD reductase activity was directly dependent on the FAD concentration, with a second-order rate constant of approximately 2.0 x 10(6) M(-1) s(-1) . Rapid-reaction studies showed that the reduction of free flavin occurred through enzyme-bound FAD, which was reduced by NADH . The peroxidase activity of NADH oxidase in the presence of FAD resulted from reduction of peroxide by free FADH(2) reduced via enzyme-bound FAD . This peroxidase activity was markedly decreased in the presence of oxygen, since the free FADH(2) is easily oxidized by oxygen, indicating that this enzyme system is unlikely to be functional in aerobic growing cells . The A . xylanus ahpC gene was cloned and overexpressed in Escherichia coli . When the NADH oxidase was coupled with A . xylanus AhpC, the peroxidase activity was not inhibited by oxygen . The V(max) values for hydrogen peroxide and cumene hydroperoxide reduction were both approximately 150 s(-1) . The K(m) values for hydrogen peroxide and cumene hydroperoxide were too low to allow accurate determination of their values . Both AhpC and NADH oxidase were induced under aerobic conditions, a clear indication that these proteins are involved in the removal of peroxides under aerobic growing conditions.

Eur J Epidemiol, 2000 Apr, 16(4), 377 - 83
Results of the three-year surveillance by the Italian SALM-NET System: human isolates of Salmonella serotypes; Scuderi G et al.; Within the wide framework of the European Community Human Salmonella Surveillance Project (SALM-NET), the data on the most commonly isolated serotypes in Italy from January 1994 to December 1996 are reported . The total data included in the Italian SALM-NET data base account for 34,412 Salmonella isolates . In the list of the most frequent isolates, S . enteritidis ranked always first in the years 1994, 1995 and 1996 with 5435 (43.4%), 4589 (37.1%) and 4044 (42.4%), respectively, over the total number of Salmonella isolates . This serotype is followed by S . typhimurium in the list of the top ten isolates, with 2236 (17.9%), 2831 (22.9%) and 2239 (23.5%) . The other serotypes included in this list accounted for a much lower number and percentages ranging from 505 isolates of S . derby (4.0%) to 99 isolates of S . brandenburg (0.8%).

Scand J Infect Dis, 2000, 32(4), 431 - 3
Salmonella virchow meningitis in an adult; Gille-Johnson P et al.; We report here a case of meningitis caused by Salmonella virchow in a woman without signs or history of immunosuppression . Salmonella meningitis is a rare complication of human salmonellosis . The patient was successfully treated with ciprofloxacin . To our knowledge, this is the first reported case of confirmed meningitis in an adult caused by this serotype.

Cytokine Growth Factor Rev, 2000 Dec, 11(4), 321 - 33
Interferon-gamma and interleukin-12 pathway defects and human disease; Dorman SE et al.; A genetic component to human mycobacterial disease susceptibility has long been postulated . Over the past five years, mutations in the interferon-gamma (IFNgamma) receptor, IL-12 receptor beta1 (IL-12Rbeta1), and IL-12 p40 genes have been recognized . These mutations are associated with heightened susceptibility to disease caused by intracellular pathogens including nontuberculous mycobacteria, vaccine-associated bacille Calmette Guerin (BCG), Salmonella species, and some viruses . We describe the genotype-phenotype correlations in IFNgamma receptor, IL-12Rbeta1, and IL-12 p40 deficiency, and discuss how study of these diseases has enhanced knowledge of human host defense against mycobacteria and other intracellular pathogens.

Microbes Infect, 2000 Jun, 2(7), 837 - 43
Small GTP binding proteins and bacterial virulence; Boquet P; Many bacterial toxins and bacterial enzymes modify small GTPases . Toxins exhibit different enzymatic activities on either the switch 1 or switch 2 domains of these small GTPases leading to inactivation or activation of such intracellular timer molecules . In addition, some virulence factors of certain invasive bacteria such as Salmonella also modulate small GTP binding proteins either by mimicking GTPase exchange factors or GTPase activating proteins.

J Chem Inf Comput Sci, 2000 Jul-Aug, 40(4), 906 - 14
Symbolic, neural, and Bayesian machine learning models for predicting carcinogenicity of chemical compounds; Bahler D et al.; Experimental programs have been underway for several years to determine the environmental effects of chemical compounds, mixtures, and the like . Among these programs is the National Toxicology Program (NTP) on rodent carcinogenicity . Because these experiments are costly and time-consuming, the rate at which test articles (i.e., chemicals) can be tested is limited . The ability to predict the outcome of the analysis at various points in the process would facilitate informed decisions about the allocation of testing resources . To assist human experts in organizing an empirical testing regime, and to try to shed light on mechanisms of toxicity, we constructed toxicity models using various machine learning and data mining methods, both existing and those of our own devising . These models took the form of decision trees, rule sets, neural networks, rules extracted from trained neural networks, and Bayesian classifiers . As a training set, we used recent results from rodent carcinogenicity bioassays conducted by the NTP on 226 test articles . We performed 10-way cross-validation on each of our models to approximate their expected error rates on unseen data . The data set consists of physical-chemical parameters of test articles, alerting chemical substructures, salmonella mutagenicity assay results, subchronic histopathology data, and information on route, strain, and sex/species for 744 individual experiments . These results contribute to the ongoing process of evaluating and interpreting the data collected from chemical toxicity studies.

J Exp Med, 2000 Aug 21, 192(4), 517 - 28
Residual type 1 immunity in patients genetically deficient for interleukin 12 receptor beta1 (IL-12Rbeta1): evidence for an IL-12Rbeta1-independent pathway of IL-12 responsiveness in human T cells; Verhagen CE et al.; Genetic lack of interleukin 12 receptor beta1 (IL-12Rbeta1) surface expression predisposes to severe infections by poorly pathogenic mycobacteria or Salmonella and causes strongly decreased, but not completely abrogated, interferon (IFN)-gamma production . To study IL-12Rbeta1-independent residual IFN-gamma production, we have generated mycobacterium-specific T cell clones (TCCs) from IL-12Rbeta1-deficient individuals . All TCCs displayed a T helper type 1 phenotype and the majority responded to IL-12 by increased IFN-gamma production and proliferative responses upon activation . This response to IL-12 could be further augmented by exogenous IL-18 . IL-12Rbeta2 was found to be normally expressed in the absence of IL-12Rbeta1, and could be upregulated by IFN-alpha . Expression of IL-12Rbeta2 alone, however, was insufficient to induce signal transducer and activator of transcription (Stat)4 activation in response to IL-12, whereas IFN-alpha/IFN-alphaR ligation resulted in Stat4 activation in both control and IL-12Rbeta1-deficient cells . IL-12 failed to upregulate cell surface expression of IL-18R, integrin alpha6, and IL-12Rbeta2 on IL-12Rbeta1-deficient cells, whereas this was normal on control cells . IL-12-induced IFN-gamma production in IL-12Rbeta1-deficient T cells could be inhibited by the p38 mitogen-activated protein kinase (MAP) kinase inhibitor SB203580 and the MAP kinase kinase (MEK) 1/2 inhibitor U0126, suggesting involvement of MAP kinases in this alternative, Stat4-independent, IL-12 signaling pathway.Collectively, these results indicate that IL-12 acts as a partial agonist in the absence of IL-12Rbeta1 . Moreover, the results reveal the presence of a novel IL-12Rbeta1/Stat4-independent pathway of IL-12 responsiveness in activated human T cells involving MAP kinases . This pathway is likely to play a role in the residual type 1 immunity in IL-12Rbeta1 deficiency.

Infect Immun, 2000 Sep, 68(9), 5401 - 4
Vacuole acidification is not required for survival of Salmonella enterica serovar typhimurium within cultured macrophages and epithelial cells; Steele-Mortimer O et al.; Phagosome acidification is an important component of the microbicidal response by infected eukaryotic cells . Thus, intracellular pathogens that reside within phagosomes must either block phagosome acidification or be able to survive at low pH . In this work, we studied the effect of phagosomal acidification on the survival of intracellular Salmonella enterica serovar Typhimurium in different cell types . Bafilomycin A1, a specific inhibitor of the vacuolar proton-ATPases, was used to block acidification of salmonella-containing vacuoles . We found that in several epithelial cell lines, treatment with bafilomycin A1 had no effect on intracellular survival or replication . Furthermore, although acidification was essential for Salmonella intracellular survival in J774 cultured macrophages, as reported previously (13), it is not essential in other macrophage cell lines . These data suggest that vacuolar acidification may play a role in intracellular survival of salmonellae only under certain conditions and in specific cell types.

Infect Immun, 2000 Sep, 68(9), 5075 - 83
Induction of colony-stimulating factor expression following Staphylococcus or Salmonella interaction with mouse or human osteoblasts; Bost KL et al.; Staphylococcus aureus and Salmonella spp . are common causes of bone diseases; however, the immune response during such infections is not well understood . Colony-stimulating factors (CSF) have a profound influence on osteoclastogenesis, as well as the development of immune responses following infection . Therefore, we questioned whether interaction of osteoblasts with two very different bacterial pathogens could affect CSF expression by these cells . Cultured mouse and human osteoblasts were exposed to various numbers of S . aureus or Salmonella dublin bacteria, and a comprehensive analysis of granulocyte-macrophage (GM)-CSF, granulocyte (G)-CSF, macrophage (M)-CSF, and interleukin-3 (IL-3) mRNA expression and cytokine secretion was performed . Expression of M-CSF and IL-3 mRNAs by mouse osteoblasts was constitutive and did not increase significantly following bacterial exposure . In contrast, GM-CSF and G-CSF mRNA expression by mouse osteoblasts was dramatically upregulated following interaction with either viable S . aureus or Salmonella . This increased mRNA expression also translated into high levels of GM-CSF and G-CSF secretion by mouse and human osteoblasts following bacterial exposure . Viable S . aureus and Salmonella induced maximal levels of CSF mRNA expression and cytokine secretion compared to UV-killed bacteria . Furthermore, GM-CSF and G-CSF mRNA expression could be induced in unexposed osteoblasts separated by a permeable Transwell membrane from bacterially exposed osteoblasts . M-CSF secretion was increased in cultures of exposed human osteoblasts but not in exposed mouse osteoblast cultures . Together, these studies are the first to define CSF expression and suggest that, following bacterial exposure, osteoblasts may influence osteoclastogenesis, as well as the development of an immune response, via the production of these cytokines.

Infect Immun, 2000 Sep, 68(9), 5050 - 5
Invasion genes are not required for Salmonella enterica serovar typhimurium to breach the intestinal epithelium: evidence that salmonella pathogenicity island 1 has alternative functions during infection; Murray RA et al.; Salmonella enterica serovar Typhimurium invasion genes are necessary for bacterial invasion of intestinal epithelial cells and are thought to allow salmonellae to enter and cross the intestinal epithelium during infection . Many invasion genes are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is activated by HilA, a transcription factor also encoded on SPI1 . We have studied the role of Salmonella invasion genes during infection of mice following intragastric inoculation . We have found that strains containing a mutation in hilA or invG were recovered from the intestinal contents, intestinal tissues, and systemic tissues at a lower frequency than their parental wild-type strain . In contrast, a strain in which SPI1 is deleted was recovered from infected mice at a frequency similar to that of its parental wild-type strain . The DeltaSPI1 phenotype indicates that S . enterica does not require invasion genes to cross the intestinal epithelium and infect systemic tissues . This result has forced us to reconsider the long-held belief that invasion genes directly mediate bacterial infection of the intestinal mucosa and traversion of the intestinal barrier during infection . Instead, our results suggest that hilA is required for bacterial colonization of the host intestine . The seemingly contradictory phenotype of the DeltaSPI1 mutant suggests that deletion of another gene(s) encoded on SPI1 suppresses the hilA mutant defect . We propose a model for S . enterica pathogenesis in which hilA and invasion genes are required for salmonellae to overcome a host clearance response elicited by another SPI1 gene product(s).

Immunol Cell Biol, 2000 Aug, 78(4), 342 - 8
New tuberculosis vaccines based on attenuated strains of the Mycobacterium tuberculosis complex; Collins DM; The world urgently needs a better tuberculosis vaccine . Bacille Calmette-Guerin (BCG), an attenuated strain of Mycobacterium bovis, has been very widely used as a vaccine for many years but has had no major effect on reducing the incidence of tuberculosis . A number of alternative living and non-living vaccines are being investigated . Live vaccine candidates include genetically modified forms of BCG, genetically attenuated strains of the Mycobacterium tuberculosis complex and genetically engineered vaccinia virus and Salmonella strains . Non-living vaccine candidates include killed mycobacterial species, protein subunits and DNA vaccines . One requirement for acceptance of any new vaccine will be a favourable comparison of the protection it induces relative to BCG in a range of animal models, some of which may need further development . Molecular genetic techniques are now available that enable production of live attenuated strains of the M . tuberculosis complex with vaccine potential . In the first of two broadly different approaches that are being used, large numbers of mutants are produced by transposon mutagenesis or illegitimate recombination and are screened for properties that correlate with attenuation . In the second approach, putative genes that may be required for virulence are identified and subsequently inactivated by allelic exchange . In both approaches, mutants that are attenuated need to be identified and subsequently tested for their vaccine efficacy in animal models . Many mutants of the M . tuberculosis complex have now been produced and the vaccine properties of a substantial number will be assessed in the next 3 years.

Poult Sci, 2000 Aug, 79(8), 1194 - 9
Bacteriological and histological profile of turkeys condemned for cyanosis; Mallia JG et al.; Canadian Food Inspection Agency (CFIA) has adopted the term cyanosis to describe a category of condemnation for poultry that is dark but has no other condemnable lesions . Two case-control studies (n = 30 pairs; n = 65 pairs) of 18-wk-old tom turkeys were conducted . A case was defined as a carcass condemned by the veterinary inspector for cyanosis, and a control carcass was one that passed inspection . Microbiological tests were conducted on samples of Pectoralis major and Gastrocnemius lacteralis . A modified Rappaport Vassiliadis medium was used for Salmonella, and a Petrifilm method was used to assess aerobic counts, coliform counts, and Escherichia coli . The Salmonella (qualitative) test was negative for all cases and controls, and there were no significant differences between the aerobic counts, coliform counts, and E . coli counts of case and control carcasses . Two pathologists conducted a blind histopathological study: there were no lesions compatible with those of septicemia-toxemia, as defined by CFIA and the USDA, nor any significant histopathological differences between the skin, P . major, G . lateralis, kidney, liver, spleen, small intestine, pancreas, lung, and heart of cases and controls . The inter-rater agreement between pathologists ranged from good to excellent (Kappa = 0.7 to 1.0) . In the absence of important lesions and microbial contamination, carcasses with this color change alone should be suitable for human consumption.

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