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novel alcohol dehydrogenase activity in a mutant of salmonella able to use ethanol as sole carbon source.we selected a mutant of salmonella enterica serovar typhimurium that is capable of growing in air on ethanol as sole carbon and energy source. this adhi mutant expressed high levels of a novel alcohol dehydrogenase (adhi) that uses ethanol, 1-propanol and 2-propanol as substrates. the fermentative adhe alcohol dehydrogenase was not expressed aerobically in the adhi mutant. anaerobically, both the novel adhi enzyme and the adhe were expressed simultaneously in the adhi mutant. however, the adhi m ...200111445165
[empyema due to salmonella enterica serotype enteritidis]. 200111446917
construction, genotypic and phenotypic characterization, and immunogenicity of attenuated deltaguaba salmonella enterica serovar typhi strain cvd 915.a promising live attenuated typhoid vaccine candidate strain for mucosal immunization was developed by introducing a deletion in the guaba locus of pathogenic salmonella enterica serovar typhi strain ty2. the resultant deltaguaba mutant, serovar typhi cvd 915, has a gene encoding resistance to arsenite replacing the deleted sequence within guaba, thereby providing a marker to readily identify the vaccine strain. cvd 915 was compared in in vitro and in vivo assays with wild-type strain ty2, licen ...200111447145
[prevalence of the salmonella plasmid virulence gene "spvd" in salmonella strains from animals].strains of salmonella isolated from animals in germany (n = 878) were analysed for the presence of the spvd gene ("salmonella plasmid virulence gene d") by dna-dna hybridization. the spvd gene was only detected in strains of serovars typhimurium (93.3%), enteritidis (97.1%), and dublin (100%) as well as in two rough strains of salmonella enterica. salmonella isolates from mammals carried the gene more frequently (cattle 94.0%, horses 92.6%, pigs 73.7%) than those from birds (33.3%) or reptiles ( ...200111449908
large drug resistance virulence plasmids of clinical isolates of salmonella enterica serovar choleraesuis.salmonella enterica serovar choleraesuis generally causes systemic human salmonellosis without diarrhea, and therefore, antimicrobial treatment is essential for such patients. the drug resistance information on this organism is thus of high value. serovar choleraesuis usually harbors a virulence plasmid (pscv) of 50 kb in size. of the 16 clinical isolates identified to be serovar choleraesuis, all except one harbored a pscv and seven of them carried a pscv of more than 125 kb in size. a pscv was ...200111451688
nonenzymatic chloramphenicol resistance mediated by incc plasmid r55 is encoded by a flor gene variant.the incc plasmid r55, initially described in the 1970s and isolated from klebsiella pneumoniae, confers nonenzymatic chloramphenicol resistance. the gene coding for this resistance was cloned and sequenced and shows 95 to 97% nucleotide identity with the recently reported flor gene from salmonella enterica serovar typhimurium dt104 and from escherichia coli animal isolates, respectively, conferring cross-resistance to florfenicol.200111451703
salmonella typhimurium-induced cytokine production and surface molecule expression by murine macrophages.the influence of salmonella enterica serovar typhimurium (s. typhimurium) on co-stimulatory molecule expression, cytokine production and induction of nitric oxide synthase (inos) by murine macrophages (mphi), as well as the influence of the phop locus on these aspects of s. typhimurium-mphi interaction, was characterized. pulsing mphi with s. typhimurium resulted in increased surface expression of mhc-i, mhc-ii, cd86 and cd54. furthermore, co-incubating s. typhimurium with mphi resulted in inter ...200111453704
the effect of lairage on salmonella isolation from market swine.the objective of this paper was to evaluate the effect of lairage (holding >12 h during transport to slaughter) in clean facilities on salmonella isolation from market swine. we tested 30 market-bound pigs (about 240 lb [110 kg]) on each of 10 occasions from an iowa farrow-to-finish operation with about 600 sows. all pigs were slaughtered, and samples were collected at a large midwest abattoir. on the farm, fecal samples were collected for culture of salmonella. pigs were alternately assigned to ...200111456200
survival and infectivity of salmonella choleraesuis in swine feces.many serotypes of salmonella survive well in the environment. conversely, it is believed that salmonella choleraesuis, the host-adapted serotype of swine, does not survive well outside the host. we examined the survival capability of salmonella choleraesuis in swine feces. six pigs were infected with salmonella choleraesuis and feces were collected and pooled on days 2, 4, 7, and 10 postinoculation (pi). feces were stored in a wet and a dry form, and survival was measured over 13 months. salmone ...200111456201
antibiotic resistance in salmonella enterica subsp. enterica strains isolated in poland from 1998 to 1999.a total of 326 salmonella enterica subsp. enterica strains representing 29 serotypes, isolated from human stool specimens during 1998-1999 in sanitary-epidemiological units in poland were tested for antibiotic susceptibility by a standard disk diffusion method. the antibiotics used were ampicillin, cefotaxime, chloramphenicol, tetracycline, streptomycin, gentamicin, kanamycin, nalidixic acid, ciprofloxacin, furazolidone, cotrimoxazole, sulphonamides and trimethoprim. in addition, 201 strains bel ...200111463524
salmonella spp. are affected by different levels of water activity in closed microcosms.controlling water activity (a(w)) can significantly impact the growth of salmonella in poultry litter and manure - a phenomenon that was studied quantitatively using two common serotypes of salmonella. the quantitative effect of changes in levels of a(w) on salmonella populations was determined using inoculated, frosted glass rectangles placed in closed chambers (microcosms). glass rectangles with known concentrations of salmonella enteritidis and s. brandenburg were placed in microcosms maintai ...200111464270
the hila box and sequences outside it determine the magnitude of hila-dependent activation of p(prgh) from salmonella pathogenicity island 1.salmonella requires genes on the salmonella pathogenicity island 1 (spi1) for the intestinal phase of infection in several models of pathogenesis. in salmonella enterica serovar typhimurium, most spi1 genes are arranged in operons that are coordinately regulated by the spi1-encoded protein hila. in the past, it has been shown that hila directly activates two promoters on spi1, p(invf-1) and p(prgh). p(invf-1) contains a hila binding site, termed a hila box, that is necessary and sufficient for a ...200111466291
comparative efficacy of various toxoids against salmonellosis in poultry.an attempt was made to develop a vaccine against salmonellosis in poultry by formalizing the salmonella toxins (enterotoxin plus cytotoxins) that have been found to be the main virulent products of the organisms. formalized (ft) and carbonated (ct) toxoids were prepared from partially purified toxins of salomella enteric subspecies enterica ser. weltevreden (bm-1643) and s. enterica ser. gallinarum (l-19/a). there was no mortality in birds vaccinated with formalized toxoid of serovar weltevreden ...200111469505
role of fimbriae as antigens and intestinal colonization factors of salmonella serovars. 200111470349
an epidemiological study of salmonella enterica serovar 4, 12:b:- in broiler chickens in denmark.epidemiological investigations of isolates of salmonella enterica serovar 4, 12:b:- were carried out to establish particular molecular markers to assign isolates to a common origin. plasmid profiling demonstrated that over 50% of 291 isolates, obtained between 1991 and 1996, were plasmid-free. the remaining isolates exhibited a common trend in plasmid content of 105 and 2kb. although no specific correlation to any particular source within the poultry industry was discernible using plasmid analys ...200111470545
effects of nondigestible oligosaccharides on salmonella enterica serovar typhimurium and nonpathogenic escherichia coli in the pig small intestine in vitro.an in vitro intestinal tissue model was developed for the investigation of bacterial association in the pig small intestine under different dietary regimes. in preliminary experiments, jejunal and ileal tissue was taken from danish landrace pigs fed standard diet and inoculated with either salmonella or nonpathogenic escherichia coli strains. higher numbers of salmonellae associated with the ileal tissues, but the numbers did not reach significance. hence, jejunal sections were inoculated with n ...200111472909
three glycoproteins with antimutagenic activity identified in lactobacillus plantarum klab21.antimutagenic substances were purified from a culture supernatant of lactobacillus plantarum klab21 cells isolated from kimchi, a korean traditional fermented vegetable, and their characteristics were investigated. the antimutagenic substances were separated into two fractions by deae-cellulose ion-exchange column chromatography, which were designated the r1 and r2 fractions. the r1 fraction was then divided into two fractions again by sephadex g200 gel filtration chromatography, and the fractio ...200111472917
antibiotic resistance in salmonella enterica serovar typhimurium exposed to microcin-producing escherichia coli.microcin 24 is an antimicrobial peptide secreted by uropathogenic escherichia coli. secretion of microcin 24 provides an antibacterial defense mechanism for e. coli. in a plasmid-based system using transformed salmonella enterica, we found that resistance to microcin 24 could be seen in concert with a multiple-antibiotic resistance phenotype. this multidrug-resistant phenotype appeared when salmonella was exposed to an e. coli strain expressing microcin 24. therefore, it appears that multidrug-r ...200111472964
atypical, fljb-negative salmonella enterica subsp. enterica strain of serovar 4,5,12:i:- appears to be a monophasic variant of serovar typhimurium.an fljb-negative, multidrug-resistant salmonella enterica serovar 4,5,12:i:- phage type dt u302 strain (resistant to ampicillin, chloramphenicol, sulfonamide, gentamicin, streptomycin, tetracycline, and sulfamethoxazole-trimethoprim) emerged and spread in spain in 1997. sequences specific for salmonella serovar typhimurium and phage type dt 104 and u302 were present in this atypical salmonella strain, suggesting that it is a monophasic salmonella serovar typhimurium variant.200111474028
analysis of outbreaks of infectious intestinal disease in ireland: 1998 and 1999.surveillance of general outbreaks of infectious gastroenteritis was introduced in 1998 by the food safety authority of ireland (fsai), in co-operation with the eight health boards. a total of 67 general outbreaks of gastroenteritis in ireland were reported to the fsai in 1998 and 1999. over 1900 people were ill as a result of these outbreaks. four percent required hospitalisation and there were two deaths. the duration of the outbreaks varied between one day and 38 days. salmonellae (44%) and sm ...200111474854
effects of carbon and nitrogen sources, sodium chloride and culture conditions on cytotoxin production by salmonella choleraesuis.the effects of carbon and nitrogen sources, incubation temperature, shaking speed, initial ph of culture broth as well as various concentration of nacl on the production of cytotoxin by salmonella choleraesuis sc-5 were evaluated in the present study. results reveal that the optimal temperature, initial medium ph and shaking speed for cytotoxin production was 37 degrees c, ph 6.0-8.0 and 100 rpm, respectively. tryptone was the best of the eight nitrogen sources tested for toxin production by s. ...200111482572
mlra, a novel regulator of curli (agf) and extracellular matrix synthesis by escherichia coli and salmonella enterica serovar typhimurium.production of curli (agf) adhesins by escherichia coli and salmonella enterica serovar typhimurium (s. typhimurium) is associated with extracellular matrix production and is optimal at low temperature during stationary phase. curli and extracellular matrix synthesis involves a complex regulatory network that is dependent on the csgd (agfd) regulator. we have identified a novel regulator, termed mlra, that is required for curli production and extracellular matrix formation. two cosmids from a gen ...200111489123
genetic line differences in survival and pathogen load in young layer chicks after salmonella enterica serovar enteritidis exposure.early infection may result in long-term colonization of layers with salmonella enterica sv. enteritidis (s. enteritidis, se), resulting in shedding into table or hatching eggs. to evaluate genetic factors underlying early response to se, genetic line differences in mortality and pathogen load at two sites (cecal lumen and spleen) were investigated. at day of hatch, chicks of four genetic lines were intra-esophageally inoculated with one of three doses of se phage type 13a. there was a significan ...200111495461
the methylcitric acid pathway in ralstonia eutropha: new genes identified involved in propionate metabolism.from ralstonia eutropha hf39 null-allele mutants were created by tn5 mutagenesis and by homologous recombination which were impaired in growth on propionic acid and levulinic acid. from the molecular, physiological and enzymic analysis of these mutants it was concluded that in this bacterium propionic acid is metabolized via the methylcitric acid pathway. the genes encoding enzymes of this pathway are organized in a cluster in the order prpr, prpb, prpc, acnm, orf5 and prpd, with prpr transcribe ...200111495997
salmonella enterica serovar gallinarum requires the salmonella pathogenicity island 2 type iii secretion system but not the salmonella pathogenicity island 1 type iii secretion system for virulence in chickens.salmonella enterica serovar gallinarum is a host-specific serotype that causes the severe systemic disease fowl typhoid in domestic poultry and a narrow range of other avian species but rarely causes disease in mammalian hosts. specificity of the disease is primarily at the level of the reticuloendothelial system, but few virulence factors have been described other than the requirement for an 85-kb virulence plasmid. in this work, by making functional mutations in the type iii secretion systems ...200111500419
conserved degp protease in gram-positive bacteria is essential for thermal and oxidative tolerance and full virulence in streptococcus pyogenes.the degp protease, a multifunctional chaperone and protease, has been shown to be essential for virulence in gram-negative pathogens such as salmonella enterica serovar typhimurium, brucella abortus, yersinia enterocolitica, and pseudomonas aeruginosa. the function of degp in pathogenesis appears to be the degradation of damaged proteins that accumulate as a result of the initial host response to infection, which includes the release of reactive oxygen intermediates. additionally, the degp prote ...200111500427
absence of all components of the flagellar export and synthesis machinery differentially alters virulence of salmonella enterica serovar typhimurium in models of typhoid fever, survival in macrophages, tissue culture invasiveness, and calf enterocolitis.in this study, we constructed an flhd (the master flagellar regulator gene) mutant of salmonella enterica serovar typhimurium and compared the virulence of the strain to that of the wild-type strain in a series of assays that included the mouse model of typhoid fever, the mouse macrophage survival assay, an intestinal epithelial cell adherence and invasion assay, and the calf model of enterocolitis. we found that the flhd mutant was more virulent than its parent in the mouse and displayed slight ...200111500437
in vivo activation of dendritic cells and t cells during salmonella enterica serovar typhimurium infection.the present study was initiated to gain insight into the interaction between splenic dendritic cells (dc) and salmonella enterica serovar typhimurium in vivo. splenic phagocytic cell populations associated with green fluorescent protein (gfp)-expressing bacteria and the bacterium-specific t-cell response were evaluated in mice given s. enterica serovar typhimurium expressing gfp and ovalbumin. flow cytometry analysis revealed that gfp-positive splenic dc (cd11c+ major histocompatibility complex ...200111500449
mechanism of therapeutic effectiveness of cefixime against typhoid fever.beta-lactams have been considered ineffective against organisms growing inside mammalian cells because of their poor penetration into cells. however, cefixime has been shown to be clinically effective against typhoid fever. the probable mechanism of therapeutic effectiveness of cefixime against typhoid fever was investigated using salmonella enterica serovar typhimurium instead of s. enterica serovar typhi both in a cellular and in a mouse infection model. cefixime was able to inhibit the growth ...200111502513
metabolic engineering of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) composition in recombinant salmonella enterica serovar typhimurium.a recombinant strain of salmonella enterica serovar typhimurium (mutant in propionate-activation activity) was metabolically engineered to control the composition of poly(3-hydroxybutyrate-co-3-hydroxy- valerate) (phbv), a polyhydroxyalkanoate copolymer with commercially desirable properties. a gene (prpe) encoding propionyl-coa synthetase was placed under the control of the iptg-inducible taclacuv5 promoter (p(taclacuv5)) while the polyhydroxyalkanoate synthesis operon (phabca) from acinetobact ...200111505380
a double antibody sandwich enzyme-linked immunosorbent assay for the detection of salmonella using biotinylated monoclonal antibodies.a double antibody sandwich enzyme-linked immunosorbent assay (elisa) was developed using monoclonal antibodies (mabs) as a rapid, economical alternative to culture isolation procedures for detection of salmonella. four mabs previously shown to react with salmonella strains representing 18 different serogroups were evaluated as capture antibodies and, after biotinylation, as detection antibodies. one mab (m183) was selected for use in the elisa to capture and detect salmonella antigens. the detec ...200111510654
a longitudinal study of salmonella enterica infections in high-and low-seroprevalence finishing swine herds in the netherlands.the purpose of this investigation was to study the incidence and course of salmonella infections in finishing pig herds in order to asses the stability of a given salmonella herd status. five low- and 7 high-seroprevalence herds were followed for seven sampling rounds. each round, blood and faecal samples were tested in an indirect elisa and by bacteriological culturing, respectively. in high-seroprevalence herds a positive salmonella status was an indication of a long-term problem and the statu ...200111513252
multiplex pcr for the detection of tetracycline resistant genes.specific primer pairs were selected for the pcr amplification of 14 tetracycline resistant genes commonly found in gram positive and gram negative organisms. combinations of primer pairs were used in multiplex pcr reactions to detect specific groups of tet genes as follows; group i tet (b), tet (c), tet (d); group ii tet (a), tet (e), tet (g); group iii tet (k), tet (l), tet (m), tet (o), tet (s); group iv teta (p), tet (q), tet (x). to test the multiplex pcr, groups i and ii were used on 25 cli ...200111513555
infective endocarditis due to an unusual serotype of salmonella.salmonellae are a rare cause of infective endocarditis. we report a case in which salmonella enterica serotype worthington was isolated from a case of endocarditis. the isolate was resistant to ampicillin, gentamicin, amikacin and chloramphenicol and sensitive to ciprofloxacin and cefotaxime.200111516040
acquisition of virulence-associated factors by the enteric pathogens escherichia coli and salmonella enterica.in this review we summarize recent genomic studies that shed light on the mechanism through which pathogenic escherichia coli and salmonella enterica have evolved. we show how acquisition of dna at specific sites on the chromosome has contributed to increased genetic variation and virulence of these two genera of the enterobacteriaceae.200111516380
structure and characterization of agfb from salmonella enteritidis thin aggregative fimbriae.the agfbac operon of salmonella enteritidis encodes thin aggregative fimbriae, fibrous, polymeric structures primarily composed of agfa fimbrins. although uncharacterized, agfb shows a 51 % overall amino acid sequence similarity to agfa. using agfb epitope-specific antiserum, agfb was detected as a minor component of whole, purified fimbriae. like agfa, agfb was released from purified fimbriae by >70 % formic acid, whereupon both agfa-agfa and agfa-agfb dimers as well as monomers were detected. ...200111518527
immunopotentiation of a developed salmonella enterica serotype enteritidis vaccine by thymulin and zinc in meat chicken breeders.the humoral immunity, spleen and thymus weight indices, lymphocyte count in the thymus cortex, and granuloma diameter at vaccination sites were assessed in four differently immunopotentiated groups of meat chicken breeders. breeders in the first two groups were given a killed salmonella enterica serotype enteritidis (se) vaccine subcutaneously at 15 and 19 weeks of age. breeders in the third and fourth groups were left unvaccinated. breeders in the first group were further immunopotentiated with ...200111519676
cloning, sequencing, and functional analysis of three glycosyltransferases involved in the biosynthesis of the inner core region of klebsiella pneumoniae lipopolysaccharide.the genes encoding the 3-deoxy-d-manno-oct-2-ulosonic acid (kdo) transferase (waaa) and heptosyltransferases i (waac) and ii (waaf) in klebsiella pneumoniae were cloned from a dna library by functional complementation of corresponding escherichia coli and salmonella enterica mutants. sequence analyses revealed extensive homologies of the deduced proteins to their counterparts in other enterobacteriaceae. however, differences were evident with regard to the chromosomal organization of the genes. ...200111521078
salmonella serotype virchow causing salmonellosis in a spanish region. characterization and survey of clones by dna fingerprinting, phage typing and antimicrobial resistance.the diversity of salmonella serotype virchow organisms causing human salmonellosis in a spanish region over 1990-1996 was studied by genetic and phenotypic procedures. isolates showing identical dna fingerprintings (ribotypes, rapd-, rep- and eric-types) were clustered into the same lineage. eight lineages were defined, of which only one caused diseases throughout the studied period. eleven phage types (pts) were represented, the most frequent being pts 8, 19, 31, throughout the study period, an ...200111523573
longitudinal study of salmonella enterica in growing pigs reared in multiple-site swine production systems.intensive longitudinal investigations of breeding and growing pig populations in two multiple-site swine production systems were conducted in nc, usa. five cohorts of sows and individually identified growing pigs from their litters were serially sampled in order to determine the prevalence and serotypes of salmonella enterica in each stage of production based on fecal culture. in addition to fecal samples, feed and environmental samples were obtained. fifteen different serotypes were isolated fr ...200111524165
salmonella enterica serovar typhimurium dt104 displays a rugose phenotype.rugose phenotypes, such as those observed in vibrio cholerae, have increased resistance to chlorine, oxidative stress, and complement-mediated killing. in this study we identified and defined a rugose phenotype in salmonella enterica serovar typhimurium dt104 and showed induction only on certain media at 25 degrees c after 3 days of incubation. incubation at 37 degrees c resulted in the appearance of the smooth phenotype. observation of the ultrastructure of the rugose form and a stable smooth v ...200111526004
effect of challenge temperature and solute type on heat tolerance of salmonella serovars at low water activity.salmonella spp. are reported to have an increased heat tolerance at low water activity (a(w); measured by relative vapor pressure [rvp]), achieved either by drying or by incorporating solutes. much of the published data, however, cover only a narrow treatment range and have been analyzed by assuming first-order death kinetics. in this study, the death of salmonella enterica serovar typhimurium dt104 when exposed to 54 combinations of temperature (55 to 80 degrees c) and a(w) (rvp 0.65 to 0.90, r ...200111526015
sodium ion cycle in bacterial pathogens: evidence from cross-genome comparisons.analysis of the bacterial genome sequences shows that many human and animal pathogens encode primary membrane na+ pumps, na+-transporting dicarboxylate decarboxylases or na+ translocating nadh:ubiquinone oxidoreductase, and a number of na+ -dependent permeases. this indicates that these bacteria can utilize na+ as a coupling ion instead of or in addition to the h+ cycle. this capability to use a na+ cycle might be an important virulence factor for such pathogens as vibrio cholerae, neisseria men ...200111528000
molecular epidemiological analysis of salmonella enterica serotype derby infections in hong kong. 200111531313
molecular epidemiological analysis of salmonella enterica serotype derby infections in hong kong.we aimed to study the antimicrobial susceptibilities and molecular epidemiology of salmonella enterica serotype derby, a unique and common salmonella serotype in hong kong.200111531322
cmy-2-producing salmonella enterica, klebsiella pneumoniae, klebsiella oxytoca, proteus mirabilis and escherichia coli strains isolated in spain (october 1999-december 2000).cmy-2 plasmid-mediated ampc beta-lactamase (cmy-2) was detected in 21 isolates from two hospitals located in different geographical regions of spain between october 1999 and december 2000. the isolates comprised two salmonella enterica serovars (mikawasima and montevideo), 16 escherichia coli, one klebsiella pneumoniae, one klebsiella oxytoca and one proteus mirabilis. in addition to the expected resistance to beta-lactams, including extended-spectrum cephalosporins and cefoxitin, all isolates s ...200111533003
extragenic suppressors of growth defects in msbb salmonella.lipid a, a potent endotoxin which can cause septic shock, anchors lipopolysaccharide (lps) into the outer leaflet of the outer membrane of gram-negative bacteria. msbb acylates (kdo)(2)-(lauroyl)-lipid iv-a with myristate during lipid a biosynthesis. reports of knockouts of the msbb gene describe effects on virulence but describe no evidence of growth defects in escherichia coli k-12 or salmonella. our data confirm the general lack of growth defects in msbb e. coli k-12. in contrast, msbb salmon ...200111544217
expression of csph, encoding the cold shock protein in salmonella enterica serovar typhimurium uk-1.both salmonella enterica serovar typhimurium and escherichia coli contain the csph gene encoding csph, one of the cold shock proteins (csps). in this study, we investigated the expression of csph in s. enterica serovar typhimurium and found that it was induced in response to a temperature downshift during exponential phase. the csph promoter was activated at 37 degrees c, and its mrna was more stable than the other csp mrnas at 37 degrees c. moreover, lacz expression of the translational csph-la ...200111544220
complete nucleotide sequence of a 43-kilobase genomic island associated with the multidrug resistance region of salmonella enterica serovar typhimurium dt104 and its identification in phage type dt120 and serovar agona.this study describes the characterization of the recently described salmonella genomic island 1 (sgi1) (d. a. boyd, g. a. peters, l.-k. ng, and m. r. mulvey, fems microbiol. lett. 189:285-291, 2000), which harbors the genes associated with the acssut phenotype in a canadian isolate of salmonella enterica serovar typhimurium dt104. a 43-kb region has been completely sequenced and found to contain 44 predicted open reading frames (orfs) which comprised approximately 87% of the total sequence. fift ...200111544236
sdia of salmonella enterica is a luxr homolog that detects mixed microbial communities.proteins of the luxr family detect the presence of n-acylhomoserine lactones (ahls) and regulate transcription accordingly. when ahls are synthesized by the same species that detects them, the system allows a bacterium to measure the population density of its own species, a phenomenon known as quorum sensing. the sdia genes of escherichia coli and salmonella enterica serovar typhimurium are predicted to encode luxr homologs. however, these species do not appear to synthesize ahls or any other mo ...200111544237
transfer of the salmonella type iii effector sope between unrelated phage families.salmonella spp. are pathogenic enterobacteria that employ type iii secretion systems to translocate effector proteins and modulate responses of host cells. the repertoire of translocated effector proteins is thought to define host specificity and epidemic virulence, and varies even between closely related salmonella strains. therefore, horizontal transfer of effector protein genes between salmonella strains plays a key role in shaping the salmonella-host interaction. several effector protein gen ...200111545581
an in-vitro model for studying the interaction of escherichia coli o157:h7 and other enteropathogens with bovine primary cell cultures.sections of kidney, trachea, ileum, colon, rectum and rumen were removed at post mortem from a neonatal calf and, with the exception of the rumen, primary cell lines were established for each of the cell types. the adherence of enterohaemorrhagic escherichia coli (ehec) serotype o157:h7, enteropathogenic e. coli (epec) serotype o111, e. coli k12 (a laboratory adapted non-pathogenic strain) and salmonella enterica serotype typhimurium was assayed on each cell type. for all adherence assays on all ...200111549177
role of the mar locus in virulence of salmonella enterica serovar typhimurium dt104 in chickens.the virulence of a salmonella enterica serovar typhimurium dt014 strain in which mara was insertionally inactivated was compared to its isogenic parent in vitro and in vivo. in vitro, the numbers of the mara mutant phagocytosed by porcine lung macrophages were significantly increased, while survival at 24 h inside macrophages and adherence to human gut cells were significantly reduced in comparison with the parent strain. in vivo, the mara inactivated strain, in competition with its parent strai ...200111549178
distribution and structural variation of the she pathogenicity island in enteric bacterial pathogens.shigella flexneri serotype 2a carries a chromosomal pathogenicity island (pai), termed the she pai, that has been implicated in the pathogenesis of diarrhoeal disease. the complete nucleotide sequence and genetic organisation of the she pai of s. flexneri 2a strain ysh6000t was determined recently. in the current study the distribution and structure of the she pai was investigated by pcr and southern analysis in 65 isolates of enteric pathogens including shigella spp., enterohaemorrhagic escheri ...200111549179
the chicken, the egg and salmonella enteritidis.salmonella enterica serovar enteritidis is the cause of the food-borne salmonellosis pandemic in humans, in part because it has the unique ability to contaminate eggs without causing discernible illness in the birds infected. the infection route to humans involves colonization, survival and multiplication of the pathogen in the hen house environment, the bird and, finally, the egg. this review highlights the stages of transmission and discusses evidence that altered bacterial growth patterns and ...200111553232
(chemo)enzymatic synthesis of dtdp-activated 2,6-dideoxysugars as building blocks of polyketide antibiotics.the flexible substrate spectrum of the recombinant enzymes from the biosynthetic pathway of dtdp-beta-l-rhamnose in salmonella enterica, serovar typhimurium (lt2), was exploited for the chemoenzymatic synthesis of deoxythymidine diphosphate- (dtdp-) activated 2,6-dideoxyhexoses. the enzymatic synthesis strategy yielded dtdp-2-deoxy-alpha-d-glucose and dtdp-2,6-dideoxy-4-keto-alpha-d-glucose (13) in a 40-60 mg scale. the nucleotide deoxysugar 13 was further used for the enzymatic synthesis of dtd ...200111553351
macrophage nitric oxide synthase associates with cortical actin but is not recruited to phagosomes.nitric oxide (no) produced from inducible no synthase (inos) is an important component of host defense against intracellular pathogens. to understand how phagocytes deliver no to ingested microorganisms while avoiding cytotoxicity, we set out to study the subcellular localization of inos within macrophages following phagocytosis. confocal microscopy of immunostained cells showed that inos was located not only diffusely within cytoplasm but also in vesicles, as well as immediately adjacent to the ...200111553583
salmonella enterica serovar typhimurium response involved in attenuation of pathogen intracellular proliferation.salmonella enterica serovar typhimurium proliferates within cultured epithelial and macrophage cells. intracellular bacterial proliferation is, however, restricted within normal fibroblast cells. to characterize this phenomenon in detail, we investigated the possibility that the pathogen itself might contribute to attenuating the intracellular growth rate. s. enterica serovar typhimurium mutants were selected in normal rat kidney fibroblasts displaying an increased intracellular proliferation ra ...200111553591
new zealand white rabbit as a nonsurgical experimental model for salmonella enterica gastroenteritis.rabbits orally challenged with salmonella enterica developed a dose-dependent diarrheal disease comparable to human salmonellosis. viable salmonella organisms recovered from the intestine and deep tissues indicate local and systemic infections. therefore, results show that the rabbit can be used as a model for diarrheal disease and sequelae associated with salmonellosis.200111553599
identification of salmonella typhi genes expressed within macrophages by selective capture of transcribed sequences (scots).salmonella enterica serovar typhi (s. typhi) is a human-restricted pathogen which causes typhoid fever. relatively little is known about s. typhi host interaction as animal models of this disease are severely limited by the lack of virulence of s. typhi in other hosts. the virulence of other salmonella serovars in animal models is dependent on the abilities of these bacteria to survive within host macrophages. we have used selective capture of transcribed sequences (scots) to identify s. typhi g ...200111555299
a rat model for dose-response relationships of salmonella enteritidis infection.to develop an animal model to study dose-response relationships of enteropathogenic bacteria.200111556909
chromosomal integration and expression of the escherichia coli k88 gene cluster in salmonella enterica ser. choleraesuis strain 54 (sc54).attempts to develop live vaccines to protect against enterotoxigenic escherichia coli (etec) infection by induction of both cell-mediated and mucosal immunity, and serum antibody responses have included use of recombinant salmonella strains that produce k88 fimbrial antigens (hone et al., 1988; attridge et al., 1988; morona et al., 1994). however, none of the recombinant salmonella vectors has been licensed by the united states department of agriculture (usda) for use as a live vaccine in pigs i ...200111557158
secretion of a putative cytotoxin in multiple antibiotic resistant salmonella enterica serotype typhimurium phagetype dt104.salmonella enterica serotype typhimurium phagetype dt104 (dt104) is a multiple antibiotic-resistant pathogen. dt104 infections have been reported in a multitude of hosts including humans, companion animals, livestock and wildlife. recently, several isolates of dt104 were recovered from veal calves exhibiting abomasitis, a finding that is inconsistent with classic salmonellosis. one of these isolates was used in murine ligated loop experiments where it was observed that multiresistant dt104 can e ...200111562173
seasonal pathogen removal by alternative on-site wastewater treatment systems.subsurface-flow constructed wetlands, sand filters, and peat filters near duluth, minnesota, were studied to determine their seasonal performance for removing pathogens from wastewater. influent was a high-strength septic tank effluent (mean values of 5-day biochemical oxygen demand, total nitrogen, and total phosphorus were 294, 96, and 15 mg/l, respectively) at the natural resources research institute's alternative treatment system test facility in northern minnesota. each treatment system was ...200111563380
wrinkled alfalfa seeds harbor more aerobic bacteria and are more difficult to sanitize than smooth seeds.at least 14 separate outbreaks of food poisoning attributed to either salmonella enterica or escherichia coli o157:h7 have been traced to sprouts in the past decade. seeds contaminated with human pathogens caused most of these outbreaks, thus many sprout growers are now treating alfalfa seeds with the sanitizing agent, calcium hypochlorite (ca[ocl]2), prior to sprouting. the efficacy of alfalfa seed sanitation varies between seed lots and between seeds within each lot. alfalfa seeds from differe ...200111563502
salmonella enterica serovar typhimurium swarming mutants with altered biofilm-forming abilities: surfactin inhibits biofilm formation.swarming motility plays an important role in surface colonization by several flagellated bacteria. swarmer cells are specially adapted to rapidly translocate over agar surfaces by virtue of their more numerous flagella, longer cell length, and encasement of slime. the external slime provides the milieu for motility and likely harbors swarming signals. we recently reported the isolation of swarming-defective transposon mutants of salmonella enterica serovar typhimurium, a large majority of which ...200111566982
ssebcd proteins are secreted by the type iii secretion system of salmonella pathogenicity island 2 and function as a translocon.the type iii secretion system encoded by salmonella pathogenicity island 2 (spi2) is required for systemic infections and intracellular accumulation of salmonella enterica. this system is induced by intracellular salmonella and subsequently transfers effector proteins into the host cell. growth conditions either inducing expression of the type iii secretion system or the secretion of substrate proteins were defined. here we report the identification of a set of substrate proteins consisting of s ...200111567004
risk factors associated with salmonella enterica prevalence in three-site swine production systems in north carolina, usa.the goal of this study was to identify risk factors associated with increased fecal shedding of salmonella enterica (se) in groups of market swine reared in large three-site production units. we conducted an intensive, long-term investigation of potential management and environmental risk factors operating during the growing phase of pig production. data regarding finisher site characteristics, biosecurity protocols, group growth performance, medication usage, and environmental temperature were ...200111570171
evaluation of cross-protection afforded by a salmonella choleraesuis vaccine against salmonella infections in pigs under field conditions.this field study investigated the efficacy of a salmonella choleraesuis live vaccine (argus sc) to reduce the number of infections with salmonella. twelve groups of about 380 pigs each were randomly allocated to either vaccination (v) or no vaccination (c). the vaccine was applied orally at 3 and 16 weeks. forty pigs per group were blood sampled at 3, 10, 16, and 24 weeks to detect possible antibodies against salmonella. the prevalence of salmonella in the lymph nodes was the major variable. in ...200111570172
impact of commercial pre-harvest processes on the prevalence of salmonella enterica in cull sows.this study examined the impact of transport and lairage on salmonella enterica prevalence in cull sows held under commercial conditions. five sampling periods over 10 weeks yielded 181 selected culls. fecal sample positives at the farm and collection point were 2% and 3%, respectively. after transport and lairage 41% of cull sows yielded s. enterica in one or more sampled tissues. a significant increase in cecal isolations was observed. the two s. enterica serotypes found at the production site ...200111570176
long-term survival and infectivity of salmonella choleraesuis.it is believed that salmonella choleraesuis, the host-adapted serotype of swine, does not survive well outside the host. we examined the survival capability as well as the presence of latent dna of s. choleraesuis in swine feces. pigs were infected with s. choleraesuis and feces was collected and pooled on days 2, 4, 7, and 10 post inoculation (pi). feces was stored in a wet and a dry form and survival was measured over 13 months. salmonella choleraesuis was recovered from wet feces through 3 mo ...200111570181
sequence polymorphism of the salmonella plasmid virulence factor d (spvd) in salmonella enterica isolates of animal origin.the nucleotide sequence encoding the salmonella plasmid virulence factor d (spvd) was determined in 17 salmonella strains that were different in o and h antigen patterns, animal host and geographical origin, and year of isolation. nucleotide sequence comparison revealed the existence of at least nine spvd alleles resulting in 8 spvd protein variants although the nucleotide sequences were highly similar (identity 98.8-100%). the spvd gene products differed from each other in up to 4 amino acid re ...200111570190
molecular analysis of a hospital cafeteria-associated salmonellosis outbreak using modified repetitive element pcr fingerprinting.a hospital cafeteria-associated outbreak of gastroenteritis due to salmonella enterica serotype infantis was retrospectively evaluated using modified repetitive element pcr (rep-pcr) fingerprinting with the eric2 and boxa1r primers and computer-assisted gel analysis and dendrogram construction. rep-pcr yielded objective between-cycler, same-strain similarity values of from 92% (composite fingerprints) to 96% (eric2 fingerprints). the 70 salmonella isolates (which included 19 serotype infantis is ...200111574555
rapid identification and antibiotic susceptibility testing of salmonella enterica serovar typhi isolated from blood: implications for therapy.the turnaround time (tat) for salmonella enterica serovar typhi identification and reporting of the antibiotic susceptibility profile was determined for 391 cases of typhoid fever, using the lysis direct plating or lysis centrifugation method of blood culture along with rapid antimicrobial susceptibility testing. the tat was more rapid (tat for 90% of the patients [tat(90)] = 30 h; tat(100) </= 67 h) than was possible with conventional methodologies and was equivalent to that reported previously ...200111574576
molecular typing of salmonella serotypes prevalent in animals in england: assessment of methodology.salmonella enterica serotypes derby, mbandaka, montevideo, livingstone, and senftenberg were among the 10 most prevalent serotypes isolated from farm animals in england and wales in 1999. these serotypes are of potential zoonotic relevance; however, there is currently no "gold standard" fingerprinting method for them. a collection of isolates representing the former serotypes and serotype gold coast were analyzed using plasmid profiling, pulsed-field gel electrophoresis (pfge), and ribotyping. t ...200111574581
isolation and characterization of a chromosomally encoded disulphide oxidoreductase from salmonella enterica serovar typhimurium.in this study, the chromosomally encoded disulphide oxidoreductase dsba from salmonella typhimurium was cloned and characterized. a survey of a number of serovars of salmonella subspecies i showed that dsba is highly conserved in most, but not all members of this subclass of salmonella species. using motility, beta-galactosidase, and alkaline phosphatase assays as indirect indicators of disulphide oxidoreductase activity, we demonstrated that dsba from s. typhimurium lt2 can only partially compl ...200111575497
persistence of escherichia coli, salmonella choleraesuis, aujeszky's disease virus and blue eye disease virus in ensilages based on the solid fraction of pig faeces.this study was carried out to determine the survival time of escherichia coli, salmonella choleraesuis, aujeszky's disease virus and blue eye disease virus in ensilages based on the solid fraction of pig faeces.200111576313
porins from salmonella enterica serovar typhimurium induce tnf-alpha, il-6 and il-8 release by cd14-independent and cd11a/cd18-dependent mechanisms.lipopolysaccharide (lps) of gram-negative bacteria and several surface components of gram-positive bacteria utilize cd14 and cd11a/18 as cellular receptors to induce expression and release of cytokines. of the surface components of gram-negative bacteria, porins exhibit a biological activity similar to that of lps. the results in this paper show that the mechanism of stimulation by porins of thp-1 cells enriched in cd14 receptor after treatment with 1,25-dihydroxyvitamin d(3) (vitamin d(3)) is i ...200111577149
genomic analysis and growth-phase-dependent regulation of the sef14 fimbriae of salmonella enterica serovar enteritidis.salmonella enterica serovar enteritidis is a leading cause of food poisoning in the usa and europe. although salmonella serovars share many fimbrial operons, a few fimbriae are limited to specific samonella serovars. sef14 fimbriae are restricted to group d salmonella and the genes encoding this virulence factor were acquired relatively recently. genomic, genetic and gene expression studies have been integrated to investigate the ancestry, regulation and expression of the sef genes. genomic comp ...200111577150
bacteremia associated with live attenuated chi8110 salmonella enterica serovar typhi isp1820 in healthy adult volunteers.live attenuated chi8110 salmonella enterica serovar typhi isp1820 vaccine was given in a dose-escalation trial to healthy, adult volunteers. positive stool and blood cultures were noted, but limited, as were immune responses measured by elisa and elispot. only volunteers with bacteremia developed immune responses; however, no symptoms were associated with bacteremia. the vaccine was insufficiently immunogenic for use as a vaccine. it is possible that reduced survival in the gut and reduced immun ...200111580224
comparison of deltarela strains of escherichia coli and salmonella enterica serovar typhimurium suggests a role for ppgpp in attenuation regulation of branched-chain amino acid biosynthesis.the growth recovery of escherichia coli k-12 and salmonella enterica serovar typhimurium deltarela mutants were compared after nutritional downshifts requiring derepression of the branched-chain amino acid pathways. because wild-type e. coli k-12 and s. enterica serovar typhimurium lt2 strains are defective in the expression of the genes encoding the branch point acetohydroxy acid synthetase ii (ilvgm) and iii (ilvih) isozymes, respectively, deltarela derivatives corrected for these mutations we ...200111591661
formation of intermediate transcription initiation complexes at pflid and pflgm by sigma(28) rna polymerase.the sigma subunit of prokaryotic rna polymerase is an important factor in the control of transcription initiation. primary sigma factors are essential for growth, while alternative sigma factors are activated in response to various stimuli. expression of class 3 genes during flagellum biosynthesis in salmonella enterica serovar typhimurium is dependent on the alternative sigma factor sigma(28). previously, a novel mechanism of transcription initiation at the flic promoter by sigma(28) holoenzyme ...200111591667
structures of bacterial flagellar motors from two flif-flig gene fusion mutants.flagella purified from salmonella enterica serovar typhimurium contain flig, flim, and flin, cytoplasmic proteins that are important in torque generation and switching, and flif, a transmembrane structural protein. the motor portion of the flagellum (the basal body complex) has a cytoplasmic c ring and a transmembrane m ring. incubation of purified basal bodies at ph 4.5 removed flim and flin but not flig or flif. these basal bodies lacked c rings but had intact m rings, suggesting that flim and ...200111591685
effect of attenuated salmonella enterica serovar typhimurium expressing a streptococcus mutans antigen on secondary responses to the cloned protein.attenuated salmonella enterica serovar typhimurium has been used for targeted delivery of recombinant antigens to gut- and nose-associated lymphoid tissues. contradictory reports have described the effect of preexisting immunity to the antigen delivery vehicle. we decided to examine this discrepancy by studying the effect of immunizing mice by the intranasal (i.n.) route with salmonella expressing an insoluble protein and to study the ability to augment recall responses by boosting with either s ...200111598028
salmonella dna adenine methylase mutants confer cross-protective immunity.salmonella isolates that lack or overproduce dna adenine methylase (dam) elicited a cross-protective immune response to different salmonella serovars. the protection afforded by the salmonella enterica serovar typhimurium dam vaccine was greater than that elicited in mice that survived a virulent infection. s. enterica serovar typhimurium dam mutant strains exhibited enhanced sensitivity to mediators of innate immunity such as antimicrobial peptides, bile salts, and hydrogen peroxide. also, s. e ...200111598044
three-dimensional tissue assemblies: novel models for the study of salmonella enterica serovar typhimurium pathogenesis.the lack of readily available experimental systems has limited knowledge pertaining to the development of salmonella-induced gastroenteritis and diarrheal disease in humans. we used a novel low-shear stress cell culture system developed at the national aeronautics and space administration in conjunction with cultivation of three-dimensional (3-d) aggregates of human intestinal tissue to study the infectivity of salmonella enterica serovar typhimurium for human intestinal epithelium. immunohistoc ...200111598087
the deltauvrb mutations in the ames strains of salmonella span 15 to 119 genes.the deltauvrb mutations present in strains of salmonella enterica typhimurium used commonly in the salmonella (ames) mutagenicity assay were isolated independently for at least five different his mutants. these deletions all involved the galactose operon, biotin operon, nucleotide-excision-repair uvrb gene, and chlorate-resistance genes. beyond this, the size of the deletions and the number and type of genes deleted have remained unknown for nearly 30 years. here, we have used genomic hybridizat ...200111600126
clearance of infection with mycobacterium bovis bcg in mice is enhanced by treatment with s28463 (r-848), and its efficiency depends on expression of wild-type nramp1 (resistance allele).the mouse bcg host resistance gene is known to control the activation of host macrophages for killing of intracellular parasites like leishmania donovani as well as intracellular bacteria, including mycobacterium bovis bcg and salmonella enterica serovar typhimurium. the nramp1 gene has been mapped to this locus and affects the efficiency of macrophage activation. it has been shown that imidazoquinoline compounds, including s28463, are able to improve the clearance of a number of intracellular p ...200111600356
families of restriction enzymes: an analysis prompted by molecular and genetic data for type id restriction and modification systems.current genetic and molecular evidence places all the known type i restriction and modification systems of escherichia coli and salmonella enterica into one of four discrete families: type ia, ib, ic or id. stysbli is the founder member of the id family. similarities of coding sequences have identified restriction systems in e.coli and klebsiella pneumoniae as probable members of the type id family. we present complementation tests that confirm the allocation of ecor9i and kpnai to the id family ...200111600708
improving recovery of salmonella enterica serovar typhimurium dt104 cells injured by heating at different water activity values.this study describes the evaluation of potentially more sensitive methods for the recovery of salmonella cells injured by heating (54 to 60 degrees c) at different water activity values (0.65 to 0.90, reduced using equal portions of glucose and fructose). these methods included gradual rehydration, the use of diluting media with added solutes or blood, the addition of blood to plating agar, and the use of different incubation temperatures and times. gradual rehydration of cells that had been cha ...200111601692
efficacy of chitosan, carvacrol, and a hydrogen peroxide-based biocide against foodborne microorganisms in suspension and adhered to stainless steel.the ability of natural compounds to inactivate foodborne organisms adhered to surfaces was investigated with the ultimate aim of replacing synthetic biocides by more environmentally friendly, natural alternatives. the antimicrobial efficacy of 0.5, 1.0, and 2.0% chitosan and spor-klenz rtu (a commercial biocide based on hydrogen peroxide and peroxyacetic acid) and 0.5, 1.25, and 2.0 mm carvacrol was determined at 20 degrees c against listeria monocytogenes, salmonella enterica serovar typhimuriu ...200111601703
bacteremia associated with naturally occuring acute coliform mastitis in dairy cows.to determine the incidence of bacteremia in dairy cows with naturally occurring acute coliform mastitis (acm) with a wide range of disease severity.200111601796
transfer of eukaryotic expression plasmids to mammalian host cells by bacterial carriers.the concept of transkingom transfer of dna from bacteria to other organisms has recently been extended to include eukaryotic host cells. intracellular bacteria have been shown to transfer eukaryotic expression plasmids to mammalian host cells in vitro and in vivo. this can be used to induce immune responses towards protein antigens encoded by the plasmid, to complement genetic defects or even to direct the production of proteins in appropriate organs. the ease of generating such vehicles makes t ...200111604322
[multidrug-resistant and fluoroquinolone-resistant salmonella enterica serotype typhimurium definitive phage type 12 isolated from infantile diarrhea].a 35-day-old male infant was admitted to our hospital, presenting a high fever, vomiting, and diarrhea. multidrug-resistant and fluoroquinolon-resistant salmonella serotype typhimurium was isolated from his stool. the phage type of the strain was dt12. the strain was resistant to ampicillin, streptomycin, gentamicin, tetracycline, chloramphenicol, sulfamethoxazole-trimethoprim, and fluoroquinolones (levofloxacin; mic 8 micrograms/ml, norfloxacin; 24 micrograms/ml, ciprofloxacin; 16 micrograms/ml ...200111605192
the isolation of antibiotic-resistant salmonella from retail ground meats.salmonella is a leading cause of foodborne illness. the emergence of antimicrobial-resistant salmonella is associated with the use of antibiotics in animals raised for food; resistant bacteria can be transmitted to humans through foods, particularly those of animal origin. we identified and characterized strains of salmonella isolated from ground meats purchased in the washington, d.c., area.200111642230
[five cases of gastroenteritis with multiresistant salmonella enterica serovar typhimurium dt104 related to farm animals in denmark].whereas the overall incidence of human salmonella infections in denmark has fallen during the past three years, the number of infections with multidrug-resistant salmonella typhimurium definitive type 104 (dt104) has risen. we report five cases of human infection with dt104 in patients living on farms, in which cattle and mixed herds of cattle and pigs were infected with dt104. transmission from the animals to the patients in the cases described is likely to have occurred. these cases emphasize ...200111665472
[outbreak of salmonella bovismorbificans infection]. 200111665476
in vivo expression from the rpos-dependent p1 promoter of the osmotically regulated prou operon in escherichia coli and salmonella enterica serovar typhimurium: activation by rho and hns mutations and by cold stress.unlike the sigma(70)-controlled p2 promoter for the osmotically regulated prou operon of escherichia coli and salmonella enterica serovar typhimurium, the sigma(s)-controlled p1 promoter situated further upstream appears not to contribute to expression of the prou structural genes under ordinary growth conditions. for s. enterica prou p1, there is evidence that promoter crypticity is the result of a transcription attenuation phenomenon which is relieved by the deletion of a 22-base c-rich segmen ...200111673423
hha is a negative modulator of transcription of hila, the salmonella enterica serovar typhimurium invasion gene transcriptional activator.an early step in the establishment of salmonella enterica serovar typhimurium murine infection is the penetration of the intestinal mucosa of the small intestine. the majority of the genes responsible for the salmonella invasive phenotype are encoded on salmonella pathogenicity island 1, and their transcription is controlled by the hila transcriptional activator. the expression of hila is regulated by environmental signals including oxygen, osmolarity, ph, and growth phase such that the presence ...200111673432
evolution of antibiotic resistance of non-typhoidal salmonellae in greece during 1990-97.susceptibility to 15 antibiotics was determined in 1548 non-typhoidal salmonella strains isolated in greece from l990 to l997. the overall prevalence of resistance of both salmonella enterica serotype enteritidis and salmonella enterica serotype typhimurium increased during the first years of the study. a decrease was observed from 1996, especially for s. enteritidis, which showed the highest overall antibiotic resistance. s. typhimurium was the serotype with the highest multiresistance to antib ...200111673638
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