Publications

host adapted serotypes of salmonella enterica.		2000	11117946
evaluation of a serological salmonella mix-elisa for poultry used in a national surveillance programme.	a mix-elisa using lipopolysaccharide antigens from salmonella enterica serotype enteritidis and typhimurium was evaluated using samples collected over time in the danish salmonella surveillance programme for poultry. serological samples (n = 42,813) taken from broiler-breeder flocks after a year of bacteriological monitoring with negative results were used for calculating the flock and individual test specificities, which were 0.997 and 0.999, respectively. layer flocks from the table egg sector ...	2000	11117948
immobilization with metal hydroxides as a means to concentrate food-borne bacteria for detection by cultural and molecular methods.	the application of nucleic acid amplification methods to the detection of food-borne pathogens could be facilitated by concentrating the organisms from the food matrix before detection. this study evaluated the utility of metal hydroxide immobilization for the concentration of bacterial cells from dairy foods prior to detection by cultural and molecular methods. using reconstituted nonfat dry milk (nfdm) as a model, two food-borne pathogens (listeria monocytogenes and salmonella enterica serovar ...	2000	10788338
lactic acid permeabilizes gram-negative bacteria by disrupting the outer membrane.	the effect of lactic acid on the outer membrane permeability of escherichia coli o157:h7, pseudomonas aeruginosa, and salmonella enterica serovar typhimurium was studied utilizing a fluorescent-probe uptake assay and sensitization to bacteriolysis. for control purposes, similar assays were performed with edta (a permeabilizer acting by chelation) and with hydrochloric acid, the latter at ph values corresponding to those yielded by lactic acid, and also in the presence of kcn. already 5 mm (ph 4. ...	2000	10788373
genetic relatedness of salmonella isolates from nondomestic birds in southeastern united states.	salmonella infections have been implicated in large-scale die-offs of wild birds in the united states. although we know quite a bit about the epidemiology of salmonella infection among domestic fowl, we know little about the incidence, epidemiology, and genetic relatedness of salmonellae in nondomestic birds. to gain further insight into salmonellae in these hosts, 22 salmonella isolates from diseased nondomestic birds were screened for the presence of virulence and antibiotic resistance-associa ...	2000	10790113
partial characterization of a genomic island associated with the multidrug resistance region of salmonella enterica typhymurium dt104.	this study describes the identification of the insertion site and partial characterization of a 43-kb region harboring the genes associated with the penta-resistant phenotype of a canadian isolate of salmonella enterica typhymurium dt104 labelled 96-5227. the 43-kb fragment, here referred to as salmonella genomic island i (sgii), was found in the genome of s. enterica typhymurium between the thdf and a prophage cp-4-like integrase (int2) gene and is flanked by an imperfect 18-bp direct repeat. a ...	2000	10930753
the cis requirements for transcriptional activation by hila, a virulence determinant encoded on spi-1.	in several models of pathogenesis, salmonella requires genes encoded on salmonella pathogenicity island 1 (spi-1) for virulence. in salmonella enterica serovar typhimurium (s. typhimurium), most spi-1 genes are arranged in operons and are co-ordinately regulated in response to environmental signals via the spi-1-encoded protein hila. in order to understand how hila controls the transcription of spi-1 genes, we have analysed the invf and prgh promoters. we have reconstituted hila-dependent activa ...	2000	10931326
mechanisms of action of rabbit cap18 on monolayers and liposomes made from endotoxins or phospholipids.	we have investigated the mechanism of action of the cationic antimicrobial protein (18 kda) cap18 on liposomes and monolayers made from phospholipids and enterobacterial lipopolysaccharides (lps). cap18 intercalates into lipid matrices composed of lps from sensitive strains, weaker into those made of lps from a resistant strain (proteus mirabilis strain r45) or negatively charged phospholipids, but not into those composed of neutral phosphatidylcholine. from the combination of data obtained with ...	2000	10931974
adhesion of salmonella enterica var enteritidis strains lacking fimbriae and flagella to rat ileal explants cultured at the air interface or submerged in tissue culture medium.	rat ileal air interface and submerged explant models were developed and used to compare the adhesion of salmonella enterica var enteritidis wild-type strains with that of their isogenic single and multiple deletion mutants. the modified strains studied were defective for fimbriae, flagella, motility or chemotaxis and binding was assessed on tissues with and without an intact mucus layer. a multiple afimbriate/aflagellate (fim-/fla-) strain, a fimbriate but aflagellate (fla-) strain and a fimbria ...	2000	10933252
the paratyphoid salmonellae.	the paratyphoid salmonella bacteria, comprising more than 2,000 serovars or serotypes, are a major problem to the poultry industry. this is largely the result of entry of the bacteria into the human food chain. human infection takes the form of a gastroenteritis, which in highly susceptible individuals can result in death. some strains of certain serotypes have the capacity to produce morbidity and mortality in very young chickens. in adult birds, some serovars become localised in the reproducti ...	2000	10935268
regulation of sigma s degradation in salmonella enterica var typhimurium: in vivo interactions between sigma s, the response regulator mvia(rssb) and clpx.	the alternate sigma factor sigmas plays an important role in the survival of salmonella typhimurium following sudden encounters with a variety of stress conditions. the level of sigmas is very low in rapidly growing cells but dramatically increases as those cells encounter environmental stress or enter into stationary phase. this increase is due in large measure to the stabilization of sigmas protein against degradation by the clpxp protease. the mvia protein, also known as rssb or spre in esche ...	2000	10939250
arguments against the replacement of type species of the genus salmonella from salmonella choleraesuis to 'salmonella enterica' and the creation of the term 'neotype species', and for conservation of salmonella choleraesuis.	the proposals of le minor and popoff in 1987 and again of euzéby in 1999 on the type species of the genus salmonella are in violation of rule 20a of the bacteriological code (1990 revision) and should be rejected. the introduction of the term 'neotype species' should be rejected. the specific epithet choleraesuis in the binary combination salmonella choleraesuis should be conserved. the serovar name choleraesuis should be changed to hogcholera.	2000	10939679
[salmonella enterica infections].		2000	10941252
constitutively expressed phop inhibits mouse-virulence of salmonella typhimurium in an spv-dependent manner.	in salmonella typhimurium, the transcription of several virulence genes including spvb is regulated by the phop/phoq regulatory system. to further examine the relationship between the phop/phoq and spv systems for virulence in mice, we examined a non-polar phop mutation combined with different virulence plasmid genotypes for effects on virulence of s. typhimurium in the mouse model. phop-/spv+ and phop-/spv- mutants were not detectably recovered from the spleens of subcutaneously or orally inocu ...	2000	10941927
salmonella infantis osteomyelitis in sickle cell disease.		2000	10942649
invb is a type iii secretion chaperone specific for sspa.	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 bindi ...	2000	11073906
genotypic analysis of multidrug-resistant salmonella enterica serovar typhi, kenya.	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.	2000	11076726
an outbreak of salmonella hadar associated with roast rabbit in a restaurant.	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 s ...	2000	11078117
salmonella enterica serovar typhimurium invasion is repressed in the presence of bile.	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 i ...	2000	11083793
regulation of salmonella enterica serovar typhimurium invasion genes by csra.	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 ...	2000	11083797
development of an in vivo model for study of intestinal invasion by salmonella enterica in chickens.	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. th ...	2000	11083838
mig-14 is a horizontally acquired, host-induced gene required for salmonella enterica lethal infection in the murine model of typhoid fever.	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 ...	2000	11083839
localization of dysfunctional tight junctions in salmonella enterica serovar typhimurium-infected epithelial layers.	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 perijunc ...	2000	11083857
role of molecular typing in an outbreak of salmonella paratyphi a.	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 stra ...	2000	11084832
natural antibiotic susceptibility of salmonella enterica strains.	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 ...	2000	11091038
pcr detection of salmonella enterica serotype montevideo in and on raw tomatoes using primers derived from hila.	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 salmon ...	2000	11097898
application of a propionyl coenzyme a synthetase for poly(3-hydroxypropionate-co-3-hydroxybutyrate) accumulation in recombinant escherichia coli.	the genetic operon for propionic acid degradation in salmonella enterica serovar typhimurium contains an open reading frame designated prpe which encodes a propionyl coenzyme a (propionyl-coa) synthetase (a. r. horswill and j. c. escalante-semerena, microbiology 145:1381-1388, 1999). in this paper we report the cloning of prpe by pcr, its overexpression in escherichia coli, and the substrate specificity of the enzyme. when propionate was utilized as the substrate for prpe, a k(m) of 50 microm an ...	2000	11097899
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.	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. reproducibili ...	2000	11097902
long-term shifts in patterns of antibiotic resistance in enteric bacteria.	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 ...	2000	11097921
simultaneous detection of salmonella strains and escherichia coli o157:h7 with fluorogenic pcr and single-enrichment-broth culture.	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 amplifie ...	2000	11097930
[systems of epidemiological typing of microorganisms responsible for hospital infections: use and evaluation].		2000	11100554
evaluation of three newly developed enzyme-linked immunosorbent assays and two agglutination tests for detecting salmonella enterica subsp. enterica serovar dublin infections in dairy cattle.	in this study test characteristics of three newly developed enzyme-linked immunosorbent assays (elisas) for salmonella enterica subsp. enterica serovar dublin were evaluated and compared with two agglutination tests. the elisas involved were an indirect elisa with serovar dublin lipopolysaccharide (lps elisa), an indirect elisa with serovar dublin flagellar antigen (gp elisa), and a double-antibody sandwich blocking elisa that uses monoclonal antibodies against s. enterica subsp. enterica serova ...	2000	11101571
prevalence of diarrheagenic escherichia coli in finns with or without diarrhea during a round-the-world trip.	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 plate ...	2000	11101575
characterization of chloramphenicol and florfenicol resistance in escherichia coli associated with bovine diarrhea.	florfenicol, a veterinary fluorinated analog of thiamphenicol, is approved for treatment of bovine respiratory pathogens in the united states. however, florfenicol resistance has recently emerged among veterinary escherichia coli isolates incriminated in bovine diarrhea. the flo gene, which confers resistance to florfenicol and chloramphenicol, has previously been identified in photobacterium piscicida and salmonella enterica serovar typhimurium dt104. the flo gene product is closely related to ...	2000	11101601
antimicrobial resistance of salmonella isolates from swine.	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.	2000	11101609
salmonella enterica serovar virchow with ctx-m-like beta-lactamase in spain.	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.	2000	11101623
differential cytokine expression in avian cells in response to invasion by salmonella typhimurium, salmonella enteritidis and salmonella gallinarum.	salmonella enterica is a facultative intracellular pathogen that is capable of causing disease in a range of hosts. although human salmonellosis is frequently associated with consumption of contaminated poultry and eggs, and the serotypes salmonella gallinarum and salmonella pullorum are important world-wide pathogens of poultry, little is understood of the mechanisms of pathogenesis of salmonella in the chicken. type iii secretion systems play a key role in host cell invasiveness and trigger th ...	2000	11101679
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.	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 ...	2000	11101680
antibiotic resistance in salmonellae isolated from humans and animals in france: comparative data from 1994 and 1997.	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 perio ...	2000	11102416
a cross-sectional study on the prevalence of listeria monocytogenes and salmonella in new york dairy herds.	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 s ...	2000	11104262
coupling of flagellar gene expression to flagellar assembly in salmonella enterica serovar typhimurium and escherichia coli.	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 occur ...	2000	11104815
salmonella typhimurium proliferates and establishes a persistent infection in the intestine of caenorhabditis elegans.	genetic analysis of host-pathogen interactions has been hampered by the lack of genetically tractable models of such interactions. we showed previously that the human opportunistic pathogen pseudomonas aeruginosa kills caenorhabditis elegans, that p. aeruginosa and c. elegans genes can be identified that affect this killing, and that most of these p. aeruginosa genes are also important for mammalian pathogenesis. here, we show that salmonella typhimurium as well as other salmonella enterica sero ...	2000	11114525
16s to 23s rrna spacer fragment length polymorphism of salmonella enterica at subspecies and serotype levels.	the variation in the lengths of the internal transcribed spacer (its) between 16s and 23s rrna genes of 101 strains representing 58 serotypes of salmonella enterica (used for salm. choleraesuis) subsp. enterica (i), salamae (ii), arizonae (iiia), diarizonae (iiib), houtenae (iv) and indica (vi) was used for typing by pcr amplification. ten fragment lengths were observed by denaturing polyacrylamide gel electrophoresis on an automatic dna sequencer resulting in 21 unique fragment patterns. ten ou ...	2000	10945789
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.	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 inoculatio ...	2000	10948124
vacuole acidification is not required for survival of salmonella enterica serovar typhimurium within cultured macrophages and epithelial cells.	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 acidifi ...	2000	10948170
a hydrogen peroxide-forming nadh oxidase that functions as an alkyl hydroperoxide reductase in amphibacillus xylanus.	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. ni ...	2000	10960086
lesions in gsha (encoding gamma-l-glutamyl-l-cysteine synthetase) prevent aerobic synthesis of thiamine in salmonella enterica serovar typhimurium lt2.	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-gluta ...	2000	10960103
phosphorylation-induced signal propagation in the response regulator ntrc.	the bacterial enhancer-binding protein ntrc is a well-studied response regulator in a two-component regulatory system. the amino (n)-terminal receiver domain of ntrc modulates the function of its adjacent output domain, which activates transcription by the sigma(54) holoenzyme. when a specific aspartate residue in the receiver domain of ntrc is phosphorylated, the dimeric protein forms an oligomer that is capable of atp hydrolysis and transcriptional activation. a chemical protein cleavage metho ...	2000	10960104
the flagellar filament of rhodobacter sphaeroides: ph-induced polymorphic transitions and analysis of the flic gene.	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 fi ...	2000	10960108
the escherichia coli o111 and salmonella enterica o35 gene clusters: gene clusters encoding the same colitose-containing o antigen are highly conserved.	o antigen is part of the lipopolysaccharide present in the outer membrane of gram-negative bacteria. escherichia coli and salmonella enterica each have many forms of o antigen, but only three are common to the two species. it has been found that, in general, o-antigen genes are of low gc content. this deviation in gc content from that of typical s. enterica or e. coli genes (51%) is thought to indicate that the o-antigen dna originated in species other than s. enterica or e. coli and was capture ...	2000	10960113
mutational analysis of genes encoding the early flagellar components of helicobacter pylori: evidence for transcriptional regulation of flagellin a biosynthesis.	we investigated the roles of flif, flis, flhb, fliq, flig, and flii of helicobacter pylori, predicted by homology to encode structural components of the flagellar basal body and export apparatus. mutation of these genes resulted in nonmotile, nonflagellate strains. western blot analysis showed that all the mutants had considerably reduced levels of both flagellin subunits and of flge, the flagellar hook protein. rna slot blot hybridization showed reduced levels of flaa mrna, indicating that tran ...	2000	10960117
prevalence of intestinal pathogens in danish finishing pig herds.	our aim was to determine the prevalence of the intestinal bacteria: lawsonia intracellularis, brachyspira hyodysenteriae, serpulina intermedia, brachyspira innocens, brachyspira pilosicoli, pathogenic escherichia coli (serogroups o138, o139, o141 and o149) and salmonella enterica in danish finishing pig herds. a total of 79 herds was randomly selected and visited during 1998. from each herd, 20 faecal samples were collected from individual pigs weighing 30-50kg. furthermore, 10 pooled pen sample ...	2000	10960714
rapid identification of salmonella typhimurium, s. enteritidis and s. virchow isolates by polymerase chain reaction based fingerprinting methods.	in this study we used and evaluated three rapid molecular typing methods for the identification of three frequent, clinically significant salmonella serovars on the basis of the ease, simplicity and reproducibility of the chosen methods. we determined the genetic diversity among several isolates of salmonella enteritidis, s. typhimiurium and s. virchow, and compared them with other enterobacteria by using the repetitive extragenic palindromic (rep) sequences, the enterobacterial repetitive inter ...	2000	10963331
engineering hydrogen sulfide production and cadmium removal by expression of the thiosulfate reductase gene (phsabc) from salmonella enterica serovar typhimurium in escherichia coli.	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 d ...	2000	10966412
resuscitation by ferrioxamine e of stressed salmonella enterica serovar typhimurium from soil and water microcosms.	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.	2000	10966440
genotypes of multidrug-resistant salmonella enterica serotype typhimurium from two regions of kenya.	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 si ...	2000	10967254
automated 5' nuclease pcr assay for identification of salmonella enterica.	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 sa ...	2000	10970396
identification of dt104 and u302 phage types among salmonella enterica serotype typhimurium isolates by pcr.	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.	2000	10970411
fecal excretion of salmonella enterica serovar typhimurium following a food-borne outbreak.	fecal excretion of salmonella enterica serovar typhimurium organisms was observed in patients and in people not showing symptoms who were involved in an outbreak of food-borne infection with this organism. excretion of organisms was prolonged in the patients who were given antimicrobial drugs compared with those who were not. the isolates were indistinguishable by their pulsed-field gel electrophoresis patterns and biotyping from the strain recovered from the roast pork that had been consumed by ...	2000	10970414
the spvb gene-product of the salmonella enterica virulence plasmid is a mono(adp-ribosyl)transferase.	a number of well-known bacterial toxins adp-ribosylate and thereby inactivate target proteins in their animal hosts. recently, several vertebrate ecto-enzymes (art1-art7) with activities similar to bacterial toxins have also been cloned. we show here that psiblast, a position-specific-iterative database search program, faithfully connects all known vertebrate ecto-mono(adp-ribosyl)transferases (madprts) with most of the known bacterial madprts. intriguingly, no matches were found in the availabl ...	2000	10972829
genetic variation of dtdp-l-rhamnose pathway genes in salmonella enterica.	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 gen ...	2000	10974117
[extra-intestinal infections caused by non-typhi salmonella serotypes. 9 yrs' experience].	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.	2000	10974765
[construction of an expression plasmid vector for accomplishing in vivo delivery of recombinant biologically active proteins. 2. synthesis of hbcag in a vaccine strain of salmonella choleraesuis].	the capacity of a previously described plasmid vector paz to deliver bioactive proteins to targets in vivo has been studied. this vector molecule has a strong constitutive promoter, is extremely stable in cells of vaccinal s. choleraesuis strain, and encodes the synthesis of marker protein beta-galactosidase which helps monitor the vector's fate in the host. the gene encoding hepatitis b virus core antigen (hbcag) has been inserted into paz under its constitutive promoter. the resultant recombin ...	2000	10975075
activation of akt/protein kinase b in epithelial cells by the salmonella typhimurium effector sigd.	the serine-threonine kinase akt is a protooncogene involved in the regulation of cell proliferation and survival. activation of akt is initiated by binding to the phospholipid products of phosphoinositide 3-kinase at the inner leaflet of the plasma membranes followed by phosphorylation at ser(473) and thr(308). we have found that akt is activated by salmonella enterica serovar typhimurium in epithelial cells. a bacterial effector protein, sigd, which is translocated into host cells via the speci ...	2000	10978351
grouping of salmonella enterica serotype montevideo strains by ribotyping and is200 profiling.	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 ...	2000	10982060
serovar specific risk factors and clinical features of salmonella enterica ssp. enterica serovar enteritidis: a study in south-west germany.	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 ...	2000	10982061
web-based visualization tools for bacterial genome alignments.	with the increase in the flow of sequence data, both in contigs and whole genomes, visual aids for comparison and analysis studies are becoming imperative. we describe three web-based tools for visualizing alignments of bacterial genomes. the first, called enteric, produces a graphical, hypertext view of pairwise alignments between a reference genome and sequences from each of several related organisms, covering 20 kb around a user-specified position. insertions, deletions and rearrangements rel ...	2000	10982867
action of the thiamine antagonist bacimethrin on thiamine biosynthesis.	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 o ...	2000	10986269
new technology for regiospecific covalent coupling of polysaccharide antigens in elisa for serological detection.	in this study we demonstrate a new uv irradiation technique for covalent coupling of bacterial polysaccharides derived from lipopolysaccharides to microtiter plates and the use of such plates in an enzyme linked immunosorbent assay (elisa). lipopolysaccharides were cleaved by mild acid hydrolysis into the lipid a part and the polysaccharide part. the polysaccharide was conjugated regiospecifically to a photochemically active compound, anthraquinone, resulting in a polysaccharide-anthraquinone co ...	2000	10986396
susceptibility to secondary bacterial infections in growing pigs as an early response in ochratoxicosis.	mycotoxic nephropathy was induced in twelve 14 kg pigs fed a dietary component, moulded by aspergillus ochraceus and contributing ochratoxin a at 1 or 3 ppm for up to 3 weeks. concurrently, salmonellosis arose spontaneously in all six animals treated at 3 ppm and all died between days 15 and 17. two of the six pigs in the 1 ppm group died similarly but the rest, and all of six control animals, were unaffected. clinical biochemistry and histology revealed changes typical of renal ochratoxicosis i ...	2000	10987179
risk factors for the occurrence of sporadic salmonella enterica serotype typhimurium infections in children in france: a national case-control study.	to determine risk factors for the occurrence of sporadic salmonella typhimurium infections among children in france, we conducted a matched case-control study. cases were identified between 15 june and 30 september 1996. we interviewed 101 pairs of case patients and control subjects, matched for age and place of residence. the risk of illness was greater for children who ate undercooked ground beef than for those who did not (odds ratio [or], 5.0; 95% confidence interval [ci], 1.9-13.1). case pa ...	2000	10987710
plasmid-mediated florfenicol resistance encoded by the flor gene in escherichia coli isolated from cattle.	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.	2000	10991873
multiple-antibiotic resistance mediated by structurally related incl/m plasmids carrying an extended-spectrum beta-lactamase gene and a class 1 integron.	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 ...	2000	10991889
high-affinity interaction between gram-negative flagellin and a cell surface polypeptide results in human monocyte activation.	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 productio ...	2000	10992449
regulation of cathelicidin gene expression: induction by lipopolysaccharide, interleukin-6, retinoic acid, and salmonella enterica serovar typhimurium infection.	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 evaluate ...	2000	10992453
salmonella enterica serovar typhimurium-dependent regulation of inducible nitric oxide synthase expression in macrophages by invasins sipb, sipc, and sipd and effector sope2.	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 expres ...	2000	10992455
human c-reactive protein is protective against fatal salmonella enterica serovar typhimurium infection in transgenic mice.	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 patho ...	2000	10992466
salmonella pathogenicity island 1-independent induction of apoptosis in infected macrophages by salmonella enterica serotype typhimurium.	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 ...	2000	10992474
comparison of abilities of salmonella enterica serovar typhimurium aroa arod and aroa htra mutants to act as live vectors.	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 pr ...	2000	10992518
identification of rpos (sigma(s))-regulated genes in salmonella enterica serovar typhimurium.	the rpos gene encodes the alternative sigma factor sigma(s) (rpos) and is required for survival of bacteria under starvation and stress conditions. it is also essential for salmonella virulence in mice. most work on the rpos regulon has been in the closely related enterobacterial species escherichia coli. to characterize the rpos regulon in salmonella, we isolated 38 unique rpos-activated lacz gene fusions from a bank of salmonella enterica serovar typhimurium mutants harboring random tn5b21 mut ...	2000	11004173
sigma(54) promoters control expression of genes encoding the hook and basal body complex in rhodobacter sphaeroides.	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 identi ...	2000	11004178
identification of a copper-responsive two-component system on the chromosome of escherichia coli k-12.	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 ...	2000	11004187
no genetic barriers between salmonella enterica serovar typhimurium and escherichia coli in sos-induced mismatch repair-deficient cells.	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.	2000	11004198
the colanic acid gene cluster of salmonella enterica has a complex history.	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 ...	2000	11004393
detection and characterisation of integrons in salmonella enterica serotype enteritidis.	integrons have been widely described among the enterobacteriaceae including strains of multi-resistant salmonella enterica serotype typhimurium dt104; however, information with respect to the presence of integrons among s. enterica serotype enteritidis strains is limited. multi-resistant isolates of enteritidis were screened for the presence of integrons using a pcr protocol. one integron was detected in all isolates that were resistant to sulfonamide and streptomycin. characterisation of these ...	2000	11004412
vesicle-mediated transfer of virulence genes from escherichia coli o157:h7 to other enteric bacteria.	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 sh ...	2000	11010892
improved template preparation for pcr-based assays for detection of food-borne bacterial pathogens.	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 ...	2000	11010913
the lipid a region of lipopolysaccharides from rhizobiaceae activates bone marrow granulocytes from lipopolysaccharide-hyporesponsive c3h/hej and c57bl/10sccr mice.	we established in previous studies that the binding of salmonella lipopolysaccharide (lps) to constitutive receptors of low affinity triggers the expression of the inducible lps-binding molecule cd14 in bone marrow cells (bmc) of c3h/heou mice, but not in bmc from c3h/hej mice. we show in this study that bmc from c3h/hej and c57bl/10sccr mice do not express cd14 after exposure to lpss from salmonella enterica and bordetella pertussis, but do express this marker when treated with several lpss fro ...	2000	11012780
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.	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 hu ...	2000	11015375
permeability barrier of the gram-negative bacterial outer membrane with special reference to nisin.	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 ...	2000	11016605
regulation of septation: a novel role for serc/pdxf in salmonella?	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 s ...	2000	11016848
bacterial virulence gene regulation: an evolutionary perspective.	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 sal ...	2000	11018137
biophysical characterization of sipa, an actin-binding protein from salmonella enterica.	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 ...	2000	11018527
application of the agar gel precipitin test to detect antibodies to salmonella enterica serovar enteritidis in serum and egg yolks from infected hens.	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 adaptati ...	2000	11020067
the effect of fecal sample weight on detection of salmonella enterica in swine feces.	the effect of different fecal sample weights on the detection of salmonella enterica in swine feces was examined. sample weights evaluated were rectal swabs and fecal samples weighing 1 g, 10 g, and 25 g. comparisons were made on matched fecal samples obtained from individual pigs housed on 2 commercial swine farms in north carolina. relative sensitivity (number of positive pigs per fecal weight category/number positive in all weight categories) increased (p < 0.001) with fecal sample weight, an ...	2000	11021427
safety and immune responses to attenuated salmonella enterica serovar typhi oral live vector vaccines expressing tetanus toxin fragment c.	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 ...	2000	11027455
phage types of salmonella enterica serovar enteritidis isolated in south africa from 1991-1995.	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 recei ...	2000	11028749
acquisition of the rfb-gnd cluster in evolution of escherichia coli o55 and o157.	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 co ...	2000	11029441
molecular characterisation of emergent multiresistant salmonella enterica serotype [4,5,12:i:-] organisms causing human salmonellosis.	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-) ...	2000	11034302
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.	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 ...	2000	11035717