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evaluation of the control of pathogen load by an anti-salmonella bacterium in a herd of cattle with persistent salmonella infection.to determine whether an anti-salmonella bacterium is involved in control of pathogen load in persistently infected cattle herds.200919119953
regulators of g-protein signalling are modulated by bacterial lipopeptides and lipopolysaccharide.regulators of g-protein signalling accelerate the gtpase activity of g(alpha) subunits, driving g proteins in their inactive gdp-bound form. this property defines them as gtpase activating proteins. here the effect of different toll-like receptor agonists on rgs1 and rgs2 expression in murine bone marrow-derived macrophages and j774 cells was analysed. after stimulation with tlr2/1 or tlr2/6 lipopeptide ligands and the tlr4/md2 ligand lipopolysaccharide, microarray analyses show only modulation ...200919120454
comparative structural and molecular characterization of ribitol-5-phosphate-containing streptococcus oralis coaggregation receptor polysaccharides.the antigenically related coaggregation receptor polysaccharides (rps) of streptococcus oralis strains c104 and sk144 mediate recognition of these bacteria by other members of the dental plaque biofilm community. in the present study, the structure of strain sk144 rps was established by high resolution nmr spectroscopy as [6galfbeta1-6galnacbeta1-3galalpha1-2ribitol-5-po(4)(-)-6galfbeta1-3galbeta1](n), thereby indicating that this polysaccharide and the previously characterized rps of strain c10 ...200919151140
rapid oligonucleotide-based recombineering of the chromosome of salmonella enterica.recombinant engineering using red recombinase-based approaches offers efficient and rapid approaches to deletion and modification of genes. here we describe a novel application of red recombinant engineering that enables direct manipulation of chromosomal loci by electroporation with short synthetic dna molecules. we demonstrate the use of this approach for the generation of scarless in-frame deletions in chromosomal genes of salmonella enterica. furthermore, we describe rapid site-directed muta ...200919151186
evaluation of the bacterial diversity in cecal contents of laying hens fed various molting diets by using bacterial tag-encoded flx amplicon pyrosequencing.laying hens are typically induced to molt to begin a new egg-laying cycle by withdrawing feed for up to 12 to 14 d. fasted hens are more susceptible to colonization and tissue invasion by salmonella enterica serovar enteritidis. much of this increased incidence in fasted hens is thought to be due to changes in the native intestinal microflora. an alternative to feed withdrawal involves feeding alfalfa meal crumble to hens, which is indigestible by poultry but provides fermentable substrate to th ...200919151343
studying the mechanism of rna separations using rna chromatography and its application in the analysis of ribosomal rna and rna:rna interactions.dna/rna chromatography presents a versatile platform for the analysis of nucleic acids. although the mechanism of separation of double stranded (ds) dna fragments is largely understood, the mechanism by which rna is separated appears more complicated. to further understand the separation mechanisms of rna using ion pair reverse phase liquid chromatography, we have analysed a number of dsrna and single stranded (ss) rna fragments. the high-resolution separation of dsrna was observed, in a similar ...200919155018
rapid dna amplification using a battery-powered thin-film resistive thermocycler.a prototype handheld, compact, rapid thermocycler was developed for multiplex analysis of nucleic acids in an inexpensive, portable configuration. instead of the commonly used peltier heating/cooling element, electric thin-film resistive heater and a miniature fan enable rapid heating and cooling of glass capillaries leading to a simple, low-cost thin-film resistive thermocycler (tfrt). computer-based pulse width modulation control yields heating rates of 6-7 k/s and cooling rates of 5 k/s. the ...200919159110
pseudogene accumulation in the evolutionary histories of salmonella enterica serovars paratyphi a and typhi.of the > 2000 serovars of salmonella enterica subspecies i, most cause self-limiting gastrointestinal disease in a wide range of mammalian hosts. however, s. enterica serovars typhi and paratyphi a are restricted to the human host and cause the similar systemic diseases typhoid and paratyphoid fever. genome sequence similarity between paratyphi a and typhi has been attributed to convergent evolution via relatively recent recombination of a quarter of their genomes. the accumulation of pseudogene ...200919159446
the salmonella pathogenicity island 2-encoded type iii secretion system is essential for the survival of salmonella enterica serovar typhimurium in free-living amoebae.free-living amoebae represent a potential reservoir and predator of salmonella enterica. through the use of type iii secretion system (t3ss) mutants and analysis of transcription of selected t3ss genes, we demonstrated that the salmonella pathogenicity island 2 is highly induced during s. enterica serovar typhimurium infection of acanthamoeba polyphaga and is essential for survival within amoebae.200919168655
salmonella enterica serovar typhimurium mutants unable to convert malate to pyruvate and oxaloacetate are avirulent and immunogenic in balb/c mice.previously, we showed that the salmonella enterica serovar typhimurium sr-11 tricarboxylic acid (tca) cycle must operate as a complete cycle for full virulence after oral infection of balb/c mice (m. tchawa yimga, m. p. leatham, j. h. allen, d. c. laux, t. conway, and p. s. cohen, infect. immun. 74:1130-1140, 2006). in the same study, we showed that for full virulence, malate must be converted to both oxaloacetate and pyruvate. moreover, it was recently demonstrated that blocking conversion of s ...200919168732
sequence analysis of the plasmid pgy1 harbored in salmonella enterica serovar paratyphi a.the cryptic plasmid pgy1, which is harbored by a clinical isolate of salmonella enterica serovar paratyphi a, was identified in a 9-year-old girl with paratyphoid fever in 2005, and its dna sequence was determined. it is 3592 bp in length and had a g+c content of 43.3%. three orfs were predicted that share low similarity with hypothetical proteins in the genbank database. pgy1 shared 36.6% sequence homology with the cryptic plasmid pimvs1 from salmonella typhimurium. its unique sequence makes it ...200919169860
acid stress activation of the sigma(e) stress response in salmonella enterica serovar typhimurium.the alternative sigma factor sigma(e) is activated by unfolded outer membrane proteins (omps) and plays an essential role in salmonella pathogenesis. the canonical pathway of sigma(e) activation in response to envelope stress involves sequential proteolysis of the anti-sigma factor rsea by the pdz proteases degs and rsep. here we show that sigma(e) in salmonella enterica sv. typhimurium can also be activated by acid stress. a sigma(e)-deficient mutant exhibits increased susceptibility to acid ph ...200919170886
isolation of salmonella enterica serotype isangi from a suspected case of enteric encephalopathy.nontyphoidal salmonella species are thought to be potentially infectious to humans and many are documented to cause human diseases. we isolated s. isangi from the blood of a 30-year-old man with complaints of diarrhoea, fever, and altered sensorium. the serotype of the isolate was confirmed at national salmonella centre (vet.), division of bacteriology and mycology, indian veterinary research institute, izzatnagar, india. the isolate was not an extended spectrum beta-lactamase (esbl) producer an ...200919172065
characterization of antimicrobial resistance in salmonella enterica serotype heidelberg isolated from food animals.fifty-eight salmonella enterica serovar heidelberg isolates isolated from food animals were tested for antimicrobial susceptibilities and further characterized for select antimicrobial resistance genes, plasmid carriage, class 1 integrons, and genetic relatedness using pulsed-field gel electrophoresis (pfge). seventy-two percent of isolates displayed resistance to at least one of the antimicrobial agents tested, while 24% exhibited resistance to eight or more antimicrobial agents. resistance was ...200919099358
mucosal immunization with attenuated salmonella enterica serovar typhi expressing protective antigen of anthrax toxin (pa83) primes monkeys for accelerated serum antibody responses to parenteral pa83 vaccine.salmonella enterica serovar typhi vaccine strain cvd 908-htra was genetically engineered for stable plasmid-based expression of protective antigen of anthrax toxin (pa83) fused with the export protein clya (clya-pa83). the priming potential of cvd 908-htra expressing clya-pa83 was assessed in 12 rhesus and 20 cynomolgus macaques that were immunized mucosally (i.e., intranasally) on days 0 and 14. a parenteral booster with purified pa83 plus alum was given to rhesus macaques on days 42 and 225; c ...200919099487
differential expression from two iron-responsive promoters in salmonella enterica serovar typhimurium reveals the presence of iron in macrophage-phagosomes.the metal status of macrophage-phagosomes during salmonella infection is largely unknown. in this study, we have precisely calibrated the metal-specificities of two metal-responsive promoters, p(irobcde) and p(sodb), from salmonella enterica serovar typhimurium and used these to directly monitor iron-levels in salmonella-containing macrophage-phagosomes. expression from the p(irobcde) promoter is highly elevated in metal-depleted media but low in media supplemented with iron or cobalt, and to a ...200919049822
selection, characterization, and application of dna aptamers for the capture and detection of salmonella enterica serovars.sensitive and specific pre-analytical sample processing methods are needed to enhance our ability to detect and quantify food borne pathogens from complex food and environmental samples. in this study, dna aptamers were selected and evaluated for the capture and detection of salmonella enterica serovar. typhimurium. a total of 66 candidate sequences were enriched against s. typhimurium outer membrane proteins (omps) with counter-selection against escherichia coli omps and lipopolysaccharides (lp ...200919049862
molecular characterisation of class 1 integrons in salmonella enterica serovar choleraesuis isolates from southern taiwan.integron-mediated multidrug resistance in salmonellaenterica serovar choleraesuis poses a major concern in human salmonellosis in taiwan. in this study, 71 strains of s. choleraesuis harbouring a class 1 integron from humans and animals were characterised for detection of integrons, gene cassettes and the spvc virulence gene using molecular genetic techniques. all 71 strains tested were negative for class 2 and 3 integrons. fifty-eight (81.7%) of the isolates harboured a class 1 integron with di ...200919084383
importance of subunit vaccine antigen of major fli c antigenic site of salmonella enteritidis ii: a challenge trial.salmonella enterica subsp. enterica serovar enteritidis (se) infection in chickens shows a mild pathogenicity except for young ages, compared with other animals, and laying hens sometimes produce se-contaminated eggs leading to public health concerns. to reduce the problem, se bacterin in poultry farms has been applied. we previously demonstrated that a subunit antigen, g.m. part polypeptide in se-fli c (sep 9), could be a candidate subunit antigen of se vaccine which may show less side effects ...200919186198
the cysteine 354 and 277 residues of salmonella enterica serovar typhi envz are determinants of autophosphorylation and ompr phosphorylation.an initial biochemical characterization of the salmonella enterica serovar typhi (s. typhi) envz sensor protein and several mutant derivatives was performed. autophosphorylation levels were higher for escherichia coli envz, intermediate for s. enterica serovar typhimurium envz and very low for s. typhi envz, in spite of their high amino acid sequence identity. consequently, ompr phosphorylation was related to envz autophosphorylation. among the mutant derivatives, a c354g mutation in s. typhi en ...200919187206
synergistic role of curli and cellulose in cell adherence and biofilm formation of attaching and effacing escherichia coli and identification of fis as a negative regulator of curli.curli are adhesive fimbriae of escherichia coli and salmonella enterica. expression of curli (csga) and cellulose (bcsa) is co-activated by the transcriptional activator csgd. in this study, we investigated the contribution of curli and cellulose to the adhesive properties of enterohaemorragic (ehec) o157:h7 and enteropathogenic e. coli (epec) o127:h6. while single mutations in csga, csgd or bcsa in epec and ehec had no dramatic effect on cell adherence, double csgabcsa mutants were significantl ...200919187284
serovar distribution and antimicrobial susceptibility of swine salmonella isolates from clinically ill pigs in diagnostic submissions from indiana in the united states.to determine serovar distribution and levels of antimicrobial susceptibility of salmonella isolated from clinically ill pigs in diagnostic submissions.200919187513
recombinant attenuated salmonella harboring 4-1bb ligand gene enhances cellular immunity.to transfect antigen presenting cells (apcs) with 4-1bb ligand dna by attenuated salmonella enterica serovar typhimurium in vivo, and to observe the effects of ectogenous 4-1bbl on the immune functions of infected rats.200919187795
rethinking typhoid fever vaccines: implications for travelers and people living in highly endemic areas. 200919192128
effects of the dicarboxylic acids malate and fumarate on e. coli o157:h7 and salmonella enterica typhimurium populations in pure culture and in mixed ruminal microorganism fermentations.the dicarboxylic acids malate and fumarate increase ruminal ph, reduce methane production, increase propionate and total volatile fatty acid (vfa) production, and reduce lactic acid accumulation in a manner similar to ionophores. these acids stimulate the ruminal bacterium selenomonas ruminantium to ferment lactate to produce propionate. thus, dicarboxylic acids have been suggested as nonantibiotic modifiers of the ruminal fermentation, but their impact on ruminal microbial ecology remains unkno ...200919194750
the structure and biological aspects of peptide antibiotic microcin j25.microcin j25 (mccj25) is a plasmid-encoded peptide of 21 l-amino acids (g1-g-a-g-h5-v-p-e-y-f10-v-g-i-g-t15-p-i-s-f-y20-g), excreted to the medium by an escherichia coli strain. mccj25 is active on gram-negative bacteria related to the producer strain, including some pathogenic strains. the four-plasmid genes mcjabcd, are involved in mccj25 production: mcja encodes a 58-residue precursor, mcjb and mcjc codify two processing enzymes required for the in vivo synthesis of the mature peptide and mcj ...200919199920
molecular characterization of antimicrobial resistance in salmonella isolated from animals in japan.aims: to investigate the prevalence of integrons and antimicrobial resistance genes in salmonella recovered from animals in japan. methods and results: forty-eight out of ninety-four (51.1%) salmonella isolates showed multidrug resistance phenotypes and harboured at least one antimicrobial resistance gene. twenty-two out of forty-seven (46.8%) salmonella enterica serovar typhimurium that were multidrug-resistant were of definitive phage type dt104. class 1 integrons were identified in 34/94 isol ...200919200308
distribution and genotypic characterization of salmonella serovars isolated from tropical seafood of cochin, india.to determine the distribution of salmonella serovars in seafood and to examine the intraserovar genetic variations in salmonella enterica subsp. enterica serovar rissen and salmonella weltevreden by polymerase chain reaction (pcr)-ribotyping and enterobacterial repetitive intergenic consensus (eric)-pcr methods.200919200318
expression of porcine toll-like receptor 2, 4 and 9 gene transcripts in the presence of lipopolysaccharide and salmonella enterica serovars typhimurium and choleraesuis.salmonella enterica serovar typhimurium (st) and choleraesuis (sc) are among the most frequently isolated salmonellae serovars causing enteric disease in swine. enteric disease in young pigs is of major concern in modern production systems due to the negative implications on animal health, food safety and economic return. epithelial cells express toll-like receptors (tlr) that recognize conserved microbial structures and act as mediators of innate and adaptive immune responses. however, little i ...200919200608
methods to monitor autophagy of salmonella enterica serovar typhimurium.autophagy is an important component of the mammalian innate immune system and is able to specifically target intracellular bacterial pathogens. salmonella enterica serovar typhimurium is an intracellular pathogen that causes gastroenteritis in humans. autophagy has been shown to target s. typhimurium during in vitro infection of mammalian cultured cells and protects the cytosol of these cells from bacterial colonization. here we discuss autophagic sequestration of s. typhimurium and how it can b ...200919200891
expression profile of toll-like receptors within the gastrointestinal tract of 2-day-old salmonella enteriditis-infected broiler chickens.salmonella enterica serovar enteriditis (se) causes a majority of foodborne illness in the u.s. a more productive avian innate immune response could reduce bacterial colonization and the incidence of infection in humans. however, quantification and comparison of the toll-like receptors (tlr), a component of the innate immune system that recognize bacterial pathogens, and their response to se colonization across the avian gastrointestinal (gi) tract has not been reported. therefore, we assessed t ...200919201111
distribution of mutation frequencies among salmonella enterica isolates from animal and human sources and genetic characterization of a salmonella heidelberg hypermutator.hypermutation is an important mechanism used by different salmonella enterica subspecies enterica to regulate genetic stability in adaptation to changing environments, including antimicrobial treatments and industrial processes. strong hypermutator strains generally contain a mutation in genes of the methyl mismatch repair (mmr) system and have mutation frequencies up to 1000-fold higher than wild type strains. the objectives of this study were to determine the distribution of mutation frequenci ...200919201550
a conserved alpha-helix essential for a type vi secretion-like system of francisella tularensis.francisella tularensis harbors genes with similarity to genes encoding components of a type vi secretion system (t6ss) recently identified in several gram-negative bacteria. these genes include igla and iglb encoding igla and iglb, homologues of which are conserved in most t6sss. we used a yeast two-hybrid system to study the interaction of the igl proteins of f. tularensis lvs. we identified a region of igla, encompassing residues 33 to 132, necessary for efficient binding to iglb, as well as f ...200919201795
innate immunity mediated by myd88 signal is not essential for induction of lipopolysaccharide-specific b cell responses but is indispensable for protection against salmonella enterica serovar typhimurium infection.salmonella organisms are gram negative and facultative anaerobic bacteria that cause typhoid fever in humans. in this study, we evaluated lps-specific adaptive immunity in innate immune-deficient mice after oral administration of attenuated salmonella enterica serovar typhimurium (s. typhimurium) strains. of interest, identical levels of lps-specific igg and iga abs were elicited in the systemic (i.e., serum and spleen) and mucosal (i.e., fecal extract and small intestine) compartments of wild-t ...200919201885
prevalence and characterization of salmonellae in commercial ground beef in the united states.commercially produced ground beef samples (n = 4,136) were collected from seven regions of the united states over a 24-month period (july 2005 to june 2007) and analyzed for the presence of salmonella enterica by using methods that concurrently provided total prevalence and enumerable levels. the overall prevalence of salmonella strains was 4.2%. enumeration showed that 94.2% were present at levels below 2 cfu/g. regional monthly prevalences of salmonella strains varied from 1.8% to 6.5% but wer ...200919201965
gfp plasmid-induced defects in salmonella invasion depend on plasmid architecture, not protein expression.we have investigated the impact of plasmids and gfp expression on invasion of cultured epithelial cells by salmonella enterica typhimurium strain sl1344. the invasiveness of sl1344 carrying plasmids derived from pbr322, encoding promoterless gfp or constitutively expressed rpsm-gfp, was compared under optimal growth conditions with that of sl1344(pbr322), unmodified sl1344 and a strain with chromosome-integrated rpsm-gfp. the strain carrying pbr322 exhibited normal invasion, but the presence of ...200919202094
surface display of the receptor-binding domain of the f17a-g fimbrial adhesin through the autotransporter aida-i leads to permeability of bacterial cells.surface exposure of antigens on bacterial cells can be critical for eliciting an effective antibody response. therefore, we investigated the cellular localization of the fimbrial f17a-g receptor-binding domain, fused to the translocator domain of the aida-i autotransporter. synthesis of the fusion protein, under the control of the l-arabinose-inducible pbad promoter, was shown to permeabilize escherichia coli k-12 and salmonella enterica serovar typhimurium cells. the presence of permeable cells ...200919202095
a novel phop-regulated locus encoding the cytolysin clya and the secreted invasin taia of salmonella enterica serovar typhi is involved in virulence.salmonella enterica serovar typhi causes a human-restricted systemic infection called typhoid fever. we have identified a typhi genomic region encoding two orfs, sty1498 and sty1499, that are expressed during infection of human macrophages and organized in an operon. sty1498 corresponds to clya, which encodes a pore-forming cytolysin, and sty1499 encodes a 27 kda protein, without any attributed function, which we have named taia (typhi-associated invasin a). in order to evaluate the roles of the ...200919202096
effects of mesalamine (5-aminosalicylic acid) on bacterial gene expression.5-aminosalicylic acid (5-asa) is a well-established treatment for inflammatory bowel disease (ibd) and may reduce the risk of colon cancer in patients with chronic colitis, but the mechanisms underlying these effects have not been fully elucidated. although 5-asa delivery is targeted to the distal gut, little is known about its effects on the luminal bacteria that reside there. intestinal bacteria are believed play a role in causing or perpetuating ibd, and bioremediation has been studied as a t ...200919202572
the potassium transporter trk and external potassium modulate salmonella enterica protein secretion and virulence.potassium (k(+)) is the most abundant intracellular cation and is essential for many physiological functions of all living organisms; however, its role in the pathogenesis of human pathogens is not well understood. in this study, we characterized the functions of the bacterial trk k(+) transport system and external k(+) in the pathogenesis of salmonella enterica, a major food-borne bacterial pathogen. here we report that trk is important for salmonella to invade and grow inside epithelial cells. ...200919001074
characterization of plasmids harbouring qnrs1, qnrb2 and qnrb19 genes in salmonella.the aim of this study was to identify and characterize plasmids carrying qnrs1, qnrb2 and qnrb19 genes identified in salmonella strains from the netherlands. the identification of plasmids may help to follow the dissemination of these resistance genes in different countries and environments.200919001452
differential mrna expression of the avian-specific toll-like receptor 15 between heterophils from salmonella-susceptible and -resistant chickens.pattern recognition receptors (prrs) are essential for recognition of conserved molecular constituents found on infectious microbes. toll-like receptors (tlrs) are a critical component of the prr repertoire and are coupled to downstream production of cytokines, chemokines, and antimicrobial peptides by tlr adaptor proteins. our laboratory previously demonstrated a role for tlr function in the differential innate response of two lines of chickens to bacterial infections. the aim of the present st ...200919002681
functional analysis of a large non-conserved region of flgk (hap1) from rhodobacter sphaeroides.the single subpolar flagellum of rhodobacter sphaeroides shows an enlarged hook-filament junction. one of the two proteins that compose this section of the filament is hap1(rs) (flgk(rs)) it contains a central non-conserved region of 860 amino acids that makes this protein about three times larger than its homologue in salmonella enterica serovar typhimurium. we investigated the role of this central portion of the unusually large hap1 protein of r. sphaeroides by monitoring the effects of serial ...200919003427
fatal community-acquired pneumonia caused by legionella pneumophila and fluoroquinolone-resistant salmonella enterica serotype choleraesuis bacteraemia. 200918993035
correlating blood immune parameters and a cct7 genetic variant with the shedding of salmonella enterica serovar typhimurium in swine.the porcine response to salmonella infection is critical for control of salmonella fecal shedding and the establishment of salmonella carrier status. in this study, 40 crossbred pigs were intranasally inoculated with salmonella enterica serovar typhimurium (salmonella typhimurium) and monitored for salmonella fecal shedding and blood immune parameters at 2, 7, 14 and 20 days post-inoculation (dpi). using a multivariate permutation test, a positive correlation was observed between salmonella typh ...200918996651
occurrence and characterization of salmonella enterica subspecies enterica serovar 9,12:l,v:- strains from bulgaria, denmark, and the united states.in 2006, salmonella enterica serovar i 9,12:l,v:- emerged in bulgaria. the aim of this study was to characterize salmonella serovar i 9,12:l,v:- isolates from bulgaria, denmark, and the united states. we compared isolates of salmonella i 9,12:l,v:- and diphasic serovars with similar antigenic formulas by pulsed-field gel electrophoresis (pfge) and antimicrobial susceptibility. the phase 2 flagellin gene (fljb) was also sequenced for selected isolates. by pfge, the salmonella i 9,12:l,v:- isolate ...200918998175
proteolytic inactivation of tissue factor pathway inhibitor by bacterial omptins.the immune response to infection includes activation of the blood clotting system, leading to extravascular fibrin deposition to limit the spread of invasive microorganisms. some bacteria have evolved mechanisms to counteract this host response. pla, a member of the omptin family of gram-negative bacterial proteases, promotes the invasiveness of the plague bacterium, yersinia pestis, by activating plasminogen to plasmin to digest fibrin. we now show that the endogenous anticoagulant tissue facto ...200918988866
multiple abscesses caused by salmonella enterica and corynebacterium pseudotuberculosis in a dromedary camel.a rare case of arthritis, peri-arthiritis and pleurits associated with salmonella enterica and corynebacterium pseudotuberculosis infection in a dromedary camel is reported. articular infections caused by non-typhoidal salmonella have been exceptionally described in human medicine. to our knowledge, this would be the first description of articular infections associated with non-thyphoidal salmonella in other mammals than humans. possible pathogenesis of the infection is discussed.200918989744
surveillance of antibiotic resistance evolution and detection of class 1 and 2 integrons in human isolates of multi-resistant salmonella typhimurium obtained in uruguay between 1976 and 2000.to study the evolution of antibiotic resistance in isolates of salmonella enterica subspecies enterica serovar typhimurium (salmonella typhimurium) obtained in uruguay between the years 1976 and 2000, and to determine the incidence of class 1 and 2 integrons in the multi-resistant isolates.200918977678
mutagenesis of region 4 of sigma 28 from chlamydia trachomatis defines determinants for protein-protein and protein-dna interactions.transcription factor sigma(28) in chlamydia trachomatis (sigma(28)(ct)) plays a role in the regulation of genes that are important for late-stage morphological differentiation. in vitro mutational and genetic screening in salmonella enterica serovar typhimurium was performed in order to identify mutants with mutations in region 4 of sigma(28)(ct) that were defective in sigma(28)-specific transcription. specially, the previously undefined but important interactions between sigma(28)(ct) region 4 ...200918978051
effect of transcriptional activators rama and soxs on expression of multidrug efflux pumps acrab and acref in fluoroquinolone-resistant salmonella typhimurium.multidrug resistance (mdr) including fluoroquinolone resistance in salmonella typhimurium can result from overexpression of efflux pumps. we examined the mechanisms of fluoroquinolone resistance among in vitro-induced ciprofloxacin-resistant salmonella typhimurium mutants, ltl and lth, derived from laboratory strain lt2.200918984645
characterization of salmonella enterica isolates from infants and toddlers in wuhan, china.extended-spectrum cephalosporins and fluoroquinolones are important antimicrobials for treating invasive salmonellosis, and emerging resistance to these antimicrobials is of paramount concern. this study reports on the antimicrobial susceptibility and molecular characterization of salmonella enterica isolates recovered in 2006 from 0- to 3-year-old outpatients in china.200918984647
porcine in vitro and in vivo models to assess the virulence of salmonella enterica serovar typhimurium for pigs.salmonella typhimurium infections in pigs pose an important human health hazard. one promising control measure is the development of live attenuated vaccine strains using defined knockout mutants. preferably, screening of candidate knockout vaccine strains for attenuation should first be done in models allowing testing of a large number of strains. thereafter, a limited number of selected strains should be further characterized in an experimental infection model in pigs. the aim of the present s ...200918987064
in ovo treatment with cpg oligodeoxynucleotides decreases colonization of salmonella enteriditis in broiler chickens.induction of the innate immune response in newly hatched chickens is important for limiting infections with bacteria, such as salmonella enterica serovar enteriditis (se). cpg oligodeoxynucleotides (cpg-odn) can stimulate the innate immune response of young chickens. therefore, we examined the effectiveness of cpg-odn administered in ovo on intestinal colonization by se and the ability to modulate the function of heterophils in young chickens. heterophils were isolated from 2-day-old chickens an ...200919019459
salmonella serovar specific upregulation of porcine defensins 1 and 2 in a jejunal epithelial cell line.defensins are important antimicrobial effector peptides of the innate immune system, which provides protection against bacterial infections in the intestine. salmonella choleraesuis and salmonella typhimurium are the most commonly isolated serovars in pig, but disease outcome is dependent on the salmonella serovar. these infections are a serious problem for the swine industry and are also posing a major threat to public health because of salmonella-related food-borne illnesses in human. to under ...200919019577
nramp1 drives an accelerated inflammatory response during salmonella-induced colitis in mice.a recently developed model for enterocolitis in mice involves pre-treatment with the antibiotic streptomycin prior to infection with salmonella enterica serovar typhimurium (s. typhimurium). the contribution of nramp1/slc11a1 protein, a critical host defence mechanism against s. typhimurium, to the development of inflammation in this model has not been studied. here, we analysed the impact of nramp1 expression on the early development of colitis using isogenic nramp1(+/+) and nramp1(-/-) mice. w ...200919016783
characterization of the myo-inositol utilization island of salmonella enterica serovar typhimurium.knockout mutation of stm4432 resulted in a growth-deficient phenotype of salmonella enterica serovar typhimurium in the presence of myo-inositol (mi) as the sole carbon source. stm4432 is part of a 22.6-kb genomic island which spans stm4417 to stm4436 (genomic island 4417/4436) and is responsible for mi degradation. genome comparison revealed the presence of this island in only six salmonella strains and a high variability of the iol gene organization in gram-negative bacteria. upon nonpolar del ...200919011032
characterisation of antimicrobial resistance-associated integrons and mismatch repair gene mutations in salmonella serotypes.in this study, we examined the presence of integrons and salmonella genomic island 1 (sgi1) and assessed their contribution to antimicrobial resistance as well as determining the extent of the mutator phenotype in salmonella isolates. a total of 81 salmonella enterica serotype typhimurium isolates were examined for the presence of integrons and sgi1 and for hypermutators using polymerase chain reaction (pcr) and the mutator assay, respectively. an additional 336 salmonella isolates were also use ...200919013057
interleukin-15 and nk1.1+ cells provide innate protection against acute salmonella enterica serovar typhimurium infection in the gut and in systemic tissues.control of bacterial colonization at mucosal surfaces depends on rapid activation of the innate immune system. interleukin-15 (il-15) directs the development, maturation, and function of a population of cells positive for nk1.1, such as natural killer (nk) cells, which are critical components of the innate immune defense against several viral and bacterial pathogens. using il-15-deficient mice, in vivo depletion of nk1.1(+) cells from wild-type mice, and in vivo overexpression of il-15 from a re ...200919015253
truncated tni module adjacent to the complex integron of salmonella genomic island 1 in salmonella enterica serovar virchow.salmonella genomic island 1 was identified for the first time in salmonella enterica serovar virchow isolated from humans in taiwan. the complex class 1 integron conferring multidrug resistance was shown to be inserted within open reading frame (orf) s023 and contains for the first time a partial transpositional module. the 5-bp target duplication flanking the complex integron suggests that its insertion in orf s023 was by transposition.200919015337
a small-molecule screen identifies the antipsychotic drug pimozide as an inhibitor of listeria monocytogenes infection.we developed a screening procedure to identify small-molecule compounds that altered infection by listeria monocytogenes to gain insights into bacterial/host cellular processes required for intracellular pathogenesis. a small-molecule library of 480 compounds with known biological functions was screened, and 21 compounds that altered the l. monocytogenes infection of murine bone marrow-derived macrophages (bmm) were identified. the identified compounds affected various cellular functions, such a ...200919015342
variation in salmonella enterica serovar typhi inchi1 plasmids during the global spread of resistant typhoid fever.a global collection of plasmids of the inchi1 incompatibility group from salmonella enterica serovar typhi were analyzed by using a combination of dna sequencing, dna sequence analysis, pcr, and microarrays. the inchi1 resistance plasmids of serovar typhi display a backbone of conserved gene content and arrangement, within which are embedded preferred acquisition sites for horizontal dna transfer events. the variable regions appear to be preferred acquisition sites for dna, most likely through c ...200919015365
salmonella induces death of cd8alpha(+) dendritic cells but not cd11c(int)cd11b(+) inflammatory cells in vivo via myd88 and tnfr1.dendritic cells (dcs), whose lifespan influences their ability to stimulate the immune system, are potent apcs that are critical for initiating immunity. here, we show that oral infection with salmonella enterica serovar typhimurium induces death of dcs in the gut-draining lymph nodes. although cd8alpha(+) dcs were sensitive to salmonella-induced death, cd8alpha(-) dcs and in particular recruited cd11c(int)cd11b(+) inflammatory cells, were resistant. infecting mice deficient for myd88 revealed t ...200919004989
influence of promoter, gene copy number, and preexisting immunity on humoral and cellular responses to a vectored antigen delivered by a salmonella enterica vaccine.attenuated salmonella strains are currently in production as vaccines for protection of animals against salmonellosis. such commercial strains offer the potential to deliver heterologous antigen to protect animals against other diseases. one vaccine strain, attenuated salmonella enterica serovar typhimurium (stm-1), was tested for the ability to deliver ovalbumin and to induce immune responses in mice. two vaccine trials were performed testing the influence of promoter choice, the location of th ...200919005022
controlled evaluation of bactec peds plus/f and bactec lytic/10 anaerobic/f media for isolation of salmonella enterica serovars typhi and paratyphi a from blood.we compared anaerobic lytic (al) and pediatric aerobic resin-containing (peds plus/f) blood culture media for the isolation of salmonella enterica serotype typhi or paratyphi a from children. the yields from al and peds plus/f media were the same with equal volumes of blood, but recovery was faster from al medium than peds plus/f medium (10.7 and 16.4 h, respectively) (p < 0.001).200919005140
tlr9-independent effects of inhibitory oligonucleotides on macrophage responses to s. typhimurium.detection of bacterial cpg-containing dna (cpg dna) by innate immune cells is dependent on toll-like receptor 9 (tlr9). here we show that the expression of tlr9 mrna was induced in mouse bone marrow-derived macrophages (bmms) upon infection with the facultative gram-negative intracellular bacterium salmonella enterica serovar typhimurium (s. typhimurium). treatment of bmm with the inhibitory oligonucleotide (odn) 2114, an antagonist of tlr9 signalling, enhanced intracellular s. typhimurium numbe ...200919048019
mechanisms of rnd multidrug efflux pumps.rnd (resistance-nodulation-division) family transporters are widespread especially among gram-negative bacteria, and catalyze the active efflux of many antibiotics and chemotherapeutic agents. they have very large periplasmic domains, and form tripartite complexes with outer membrane channels and periplasmic adaptor proteins. acrab-tolc complex of escherichia coli, which pumps out a very wide range of drugs, has been studied most intensively. early studies showed that the transporter captures ev ...200919026770
effect of sample preparation and bacterial concentration on salmonella enterica detection in poultry meat using culture methods and pcr assaying of preenrichment broths.we evaluated the sensitivity of a pcr assay in the detection of salmonella enterica at the broth preenrichment step of poultry meat. a total of 162 retail poultry meat samples, which were prepared by manual massaging, stomacher or no homogenization were compared for salmonella recovery. using these homogenization methods, the pcr assay at the broth preenrichment step detected salmonella in, respectively, 48.9%, 62.2% and 50.0% of meat and giblet samples detected as salmonella-positive using the ...200919028296
interaction of enteric bacterial pathogens with murine embryonic stem cells.embryonic stem (es) cells are susceptible to genetic manipulation and retain the potential to differentiate into diverse cell types, which are factors that make them potentially attractive cells for studying host-pathogen interactions. murine es cells were found to be susceptible to invasion by salmonella enterica serovar typhimurium and shigella flexneri and to the formation of attaching and effacing lesions by enteropathogenic escherichia coli. s. enterica serovar typhimurium and s. flexneri c ...200919029302
qnrd, a novel gene conferring transferable quinolone resistance in salmonella enterica serovar kentucky and bovismorbificans strains of human origin.in a previous study, four salmonella isolates from humans in the henan province of china showed reduced susceptibility to ciprofloxacin (mic, 0.125 to 0.25 microg/ml) but were susceptible to nalidixic acid (mic, 4 to 8 microg/ml). all isolates were negative for known qnr genes (a, b, and s), aac(6')ib-cr, and mutations in gyra and parc. plasmid dna was extracted from all four isolates and transformed into escherichia coli tg1 and dh10b cells by electroporation, and transformants were selected on ...200919029321
csra and csrb are required for the post-transcriptional control of the virulence-associated effector protein avra of salmonella enterica.the virulence-associated effector protein avra of salmonella enterica is an ubiquitin-like acetyltransferase/cysteine protease, which interferes with the first line of immune response of the target organism. in contrast to translation of the avra protein in s. enterica strains, which takes place either constitutively (class 1 strains), or after acid induction (class 2 strains), or not at all (class 3 strains); the constitutive transcription of the respective avra genes occurs regardless of these ...200919042154
regulation of salmonella-induced membrane ruffling by sipa differs in strains lacking other effectors.the salmonella pathogenicity island 1 (spi-1) type three secretion system (ttss) is essential for salmonella invasion of host cells through its triggering of actin-dependent membrane ruffles. the spi-1 effectors sipa, sope, sope2 and sopb all have actin regulating activities and contribute to invasion. the precise role of actin regulation by sipa in salmonella invasion remains controversial since divergent data have been presented regarding the relationship between sipa and membrane ruffling. we ...200919046340
the malf p2 loop of the atp-binding cassette transporter malfgk2 from escherichia coli and salmonella enterica serovar typhimurium interacts with maltose binding protein (male) throughout the catalytic cycle.we have investigated the interaction of the uncommonly large periplasmic p2 loop of the malf subunit of the maltose atp-binding cassette transporter (malfgk(2)) from escherichia coli and salmonella enterica serovar typhimurium with maltose binding protein (male) by site-specific chemical cross-linking in the assembled transport complex. we focused on possible distance changes between two pairs of residues of the p2 loop and male during the transport cycle. the distance between malf(s205c) and ma ...200919047355
public health assessment of salmonella enterica serovar enteritidis inactivated-vaccine treatment in layer flocks.although there have been several reports on the efficacy assessment of a salmonella enterica serovar enteritidis vaccine against intestinal and parenchymatous organ diseases of laying hens, no public health risk characterization of its long-term effect on eggs has been reported. in this study, we attempted to assess the public health effect of an inactivated s. enterica serovar enteritidis vaccine against serovar enteritidis contamination of chicken eggs. we analyzed serovar enteritidis isolatio ...200919047380
detection of qnr genes in salmonella isolated from humans in denmark. 200919056747
probiotic bacteria are antagonistic to salmonella enterica and campylobacter jejuni and influence host lymphocyte responses in human microbiota-associated immunodeficient and immunocompetent mice.a defined human microbiota-associated (hma) mouse model in balb/c and immunodeficient tgepsilon26 mice was used to assess the ability of probiotic lactobacilli and bifidobacteria to enhance colonization resistance to gastrointestinal (gi) tract pathogens. probiotic bacteria (1x10(8) colony forming unit (cfu)/ml) successfully excluded campylobacter jejuni from both strains of mice 7 days after challenge. the probiotic bacteria also reduced the number of salmonella in the large intestines of both ...200919065588
construction of phage mutants.recent studies have established that the most abundant life form, that of phages, has had major influence on the biosphere, bacterial evolution, bacterial genome, and lateral gene transmission. importantly the phages have served and continue to serve as valuable model systems. such studies have led to a renewed interest and activity in the study of phages and their genomes. in order to determine the details of the involvement of phages in these important processes and activities, it is critical ...200919066824
generalized transduction.transduction is the process in which bacterial dna is transferred from one bacterial cell to another by means of a phage particle. there are two types of transduction, generalized transduction and specialized transduction. in this chapter two of the best-studied systems - escherichia coli-phage p1, and salmonella enterica-phage p22 - are discussed from theoretical and practical perspectives.200919066827
detection of salmonella in finishing pigs on farm and at slaughter in piedmont, italy.salmonella is one of the most common causes of human gastroenteritis often associated with pork consumption. the aims of this cross-sectional study were to collect preliminary data on the presence of salmonella enterica in pigs in piedmont (italy), through sampling on farm and at slaughter and to gather pilot data on serotypes and phagetypes present in the sampled area and distribution of anti-microbial resistance among isolated strains. salmonella was detected through culture and identified wit ...200919068072
aroa and arod mutations influence biofilm formation in salmonella enteritidis.aro mutants of salmonella enterica are frequently used as live vaccines for the oral vaccination of domestic animals. interestingly, besides their auxotrophy, they appear to be of reduced resistance to the components of innate immune response due to a defect in outer membrane and/or cell wall integrity. because different extracellular structures associated with the cell wall or outer membrane are involved in biofilm formation, we were interested in the ability of aroa and arod mutants of s. ente ...200919054077
the survival of salmonella enterica serovar typhimurium dt104 and total viable counts on beef surfaces at different relative humidities and temperatures.the aim of this study was to investigate changes in salmonella and total viable count (tvc) survival on beef carcass surfaces stored for 72 h under different combinations of relative humidity (i.e. rh 75% or 96%) and temperature (5 degrees c or 10 degrees c).200919054240
the immunobiology of avian systemic salmonellosis.avian systemic salmonellosis is primarily caused by salmonella enterica serovar gallinarum and serovar pullorum causing the diseases fowl typhoid and pullorum disease respectively. during infection interaction with the immune system occurs in three main phases. first is invasion via the gastrointestinal tract. infection with s. pullorum or s. gallinarum does not cause substantial inflammation, unlike s. typhimurium or s. enteritidis. through in vitro models it was found that s. gallinarum does n ...200919070366
oral delivery of dna vaccine encoding vp28 against white spot syndrome virus in crayfish by attenuated salmonella typhimurium.protective immune responses in shrimp induced by dna vaccines against white spot syndrome virus (wssv) with intramuscular injection have been reported in recent reports. in this study, we investigated the utilities of attenuated salmonella enterica serovar typhimurium (salmonella typhimurium) as a bactofection vehicle for the oral delivery of a dna vaccine plasmid to crayfish (cambarus clarkii). the dna vaccine plasmid pcdna3.1-vp28, encoding viral envelope protein vp28, was transformed to an at ...200919071178
outbreak of salmonella enterica serotype montevideo infections in france linked to consumption of cheese made from raw milk.in 2006, an outbreak of salmonella enterica serotype montevideo infections occurred in france. a matched case-control study and microbiological, environmental, and veterinary investigations were conducted to determine the source of this outbreak. a case was defined as a resident of france in whom salmonella montevideo was isolated from a stool or blood specimen between october 16, 2006, and january 6, 2007. patients were interviewed using a standardized questionnaire. salmonella montevideo food ...200919072083
bacterial dna topology and infectious disease.the gram-negative bacterium escherichia coli and its close relative salmonella enterica have made important contributions historically to our understanding of how bacteria control dna supercoiling and of how supercoiling influences gene expression and vice versa. now they are contributing again by providing examples where changes in dna supercoiling affect the expression of virulence traits that are important for infectious disease. available examples encompass both the earliest stages of pathog ...200919073701
molecular characterization and antimicrobial susceptibility of salmonella isolates from infections in humans in henan province, china.we characterized 208 human salmonella isolates from 2006 to 2007 and 27 human salmonella enterica serovar typhimurium isolates from 1987 to 1993 from henan province, china, by serotyping, by antimicrobial susceptibility testing, and, for the most common serovars, by pulsed-field gel electrophoresis (pfge). the most common serovars among the 2006-2007 isolates were s. enterica serovar typhimurium (27%), s. enterica serovar enteritidis (17%), s. enterica serovar derby (10%), s. enterica serovar in ...200919073874
leucine-responsive regulatory protein (lrp) acts as a virulence repressor in salmonella enterica serovar typhimurium.leucine-responsive regulatory protein (lrp) is a global gene regulator that influences expression of a large number of genes including virulence-related genes in escherichia coli and salmonella. no systematic studies examining the regulation of virulence genes by lrp have been reported in salmonella. we report here that constitutive expression of lrp [lrp(con)] dramatically attenuates salmonella virulence while an lrp deletion (deltalrp) mutation enhances virulence. the lrp(con) mutant caused pl ...200919074398
association of is26-composite transposons and complex in4-type integrons generates novel multidrug resistance loci in salmonella genomic island 1.clinical isolates of salmonella enterica serovar haifa and newport, which displayed extended multidrug resistance phenotypes, were investigated for the presence of salmonella genomic island 1 (sgi1) and the genetic organization of its antibiotic resistance gene clusters.200919074421
identification and characterization of class 1 integron resistance gene cassettes among salmonella strains isolated from imported seafood.a total of 210 salmonella isolates, representing 64 different serovars, were isolated from imported seafood samples, and 55/210 isolates were found to be resistant to at least one antibiotic. class 1 integrons from three multidrug-resistant salmonella enterica strains (salmonella enterica serovars newport [strain 62], typhimurium var. copenhagen [strain 629], and lansing [strain 803], originating from hong kong, the philippines, and taiwan, respectively) were characterized. southern hybridizatio ...200919074612
a mixture containing galactooligosaccharide, produced by the enzymic activity of bifidobacterium bifidum, reduces salmonella enterica serovar typhimurium infection in mice.the prebiotic bimuno is a mixture containing galactooligosaccharide, produced by the galactosyltransferase activity of bifidobacterium bifidum ncimb 41171 in the presence of lactose. previous studies have implicated prebiotics in reducing infections by enteric pathogens, thus it was hypothesized that bimuno may confer some protection in the murine host from salmonella enterica serovar typhimurium (s. typhimurium) infection. in this study, infection caused by s. typhimurium sl1344nal(r) in the pr ...200919074651
characterization of bacteriophages used in the salmonella enterica serovar enteritidis phage-typing scheme.the 16 salmonella enterica serovar enteritidis (s. enteritidis) typing phages (setps) used in the laboratory of enteric pathogens (health protection agency, london, uk) phage-typing scheme have not previously been characterized in detail. we have examined the adsorption properties of the phages with respect to a number of s. enterica serovars and defined phage morphology with electron microscopy. pfge was used to estimate overall genome size and banding patterns generated by electrophoresis foll ...200919074657
downregulation of rpon-controlled genes protects salmonella cells from killing by the cationic antimicrobial peptide polymyxin b.salmonella enterica polymyxin b (pm) resistance is modulated mainly by substitutions of the acyl chains and the phosphate groups on the lipid a moiety of lipopolysaccharide. these modifications are mediated by genes under the control of the pmra/pmrb and phop/phoq two-component regulatory systems. in this study, a deletion in the gene encoding the alternative sigma(54) factor, rpon, was shown to increase pm resistance without affecting protamine sensitivity. the results presented here showed tha ...200919076233
subversion of antimicrobial calprotectin (s100a8/s100a9 complex) in the cytoplasm of tr146 epithelial cells after invasion by listeria monocytogenes.expressed by squamous mucosal keratinocytes, calprotectin is a complex of two ef-hand calcium-binding proteins of the s100 subfamily (s100a8 and s100a9) with significant antimicrobial activity. calprotectin-expressing cells resist invasion by porphyromonas gingivalis, listeria monocytogenes, and salmonella enterica serovar typhimurium (s. typhimurium). to understand the interactions between calprotectin and invasive bacteria, we studied the distribution of calprotectin in the cytoplasm of tr146 ...200919079333
a dynamic view of the spread and intracellular distribution of salmonella enterica.the events that determine the dynamics of proliferation, spread and distribution of microbial pathogens within their hosts are surprisingly heterogeneous and poorly understood. we contend that understanding these phenomena at a sophisticated level with the help of mathematical models is a prerequisite for the development of truly novel, targeted preventative measures and drug regimes. we describe here recent studies of salmonella enterica infections in mice which suggest that bacteria resist the ...200919079353
in vitro activity of gentamicin and amikacin against salmonella enterica serovar typhi: a search for a treatment regimen for typhoid fever.the emergence of salmonella enterica serovar typhi isolates resistant to ciprofloxacin and 3rd-generation cephalosporins is a concern for physicians in developing countries. this study assessed the in vitro activity of gentamicin and amikacin against 464 s. entenca serovar typhi isolates obtained from blood of patients clinically suspected of enteric fever who attended the calcutta school of tropical medicine from 1991 to 2003. the isolates were sensitive to gentamicin and amikacin, showing mini ...200919554971
development of a cell culture method to isolate and enrich salmonella enterica serotype enteritidis from shell eggs for subsequent detection by real-time pcr.salmonella enterica serotype enteritidis is a major cause of nontyphoidal salmonellosis from ingestion of contaminated raw or undercooked shell eggs. current techniques used to identify salmonella serotype enteritidis in eggs are extremely laborious and time-consuming. in this study, a novel eukaryotic cell culture system was combined with real-time pcr analysis to rapidly identify salmonella serotype enteritidis in raw shell eggs. the system was compared to the standard microbiological method o ...200919561188
virulotyping of salmonella enterica subsp. enterica isolated from indigenous vegetables and poultry meat in malaysia using multiplex-pcr.the increased occurrence of salmonella occurrence in local indigenous vegetables and poultry meat can be a potential health hazards. this study is aimed to detect the prevalence of twenty different virulence factors among salmonella enterica strains isolated from poultry and local indigenous vegetables in malaysia via an optimized, rapid and specific multiplex pcr assay. the assay encompasses a total of 19 salmonella pathogenicity islands genes and a quorum sensing gene (sdia) in three multiplex ...200919565351
evaluation of quinolones for use in detection of determinants of acquired quinolone resistance, including the new transmissible resistance mechanisms qnra, qnrb, qnrs, and aac(6')ib-cr, in escherichia coli and salmonella enterica and determinations of wild-type distributions.fluoroquinolone resistance in members of the enterobacteriaceae family is mostly due to mutations in the quinolone resistance-determining regions of the topoisomerase genes. however, transferable genes encoding quinolone resistance have recently been described. the current methods for susceptibility testing are not adapted to the detection of new resistance determinants, which confer low levels of resistance. the aim of this study was to compare the ability of the screening of the different quin ...200919571019
who global salm-surv external quality assurance system for serotyping of salmonella isolates from 2000 to 2007.an international external quality assurance system (eqas) for the serotyping of salmonella species was initiated in 2000 by who global salm-surv to enhance the capacity of national reference laboratories to obtain reliable data for surveillance purposes worldwide. seven eqas iterations were conducted between 2000 and 2007. in each iteration, participating laboratories submitted serotyping results for eight salmonella isolates. a total of 249 laboratories in 96 countries participated in at least ...200919571024
association of virulence plasmid and antibiotic resistance determinants with chromosomal multilocus genotypes in mexican salmonella enterica serovar typhimurium strains.bacterial genomes are mosaic structures composed of genes present in every strain of the same species (core genome), and genes present in some but not all strains of a species (accessory genome). the aim of this study was to compare the genetic diversity of core and accessory genes of a salmonella enterica subspecies enterica serovar typhimurium (typhimurium) population isolated from food-animal and human sources in four regions of mexico. multilocus sequence typing (mlst) and macrorestriction f ...200919573249
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