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the prevalence of salmonella enterica in spanish feed mills and potential feed-related risk factors for contamination.a cross-sectional study was conducted in spain to estimate the prevalence of salmonella enterica in feed mills and to identify and evaluate potential risk factors associated with feed contamination. a total of 3844 samples were collected from 523 different feed mills using a stratified sampling method. samples were tested for the presence of salmonella using conventional culture methods. when the presence of salmonella was detected, samples were further characterised using serotyping at the nati ...201021145122
response regulator arca of salmonella enterica serovar typhimurium downregulates expression of ompd, a porin facilitating uptake of hydrogen peroxide.here we demonstrate that ompd, the most abundant porin in salmonella enterica serovar typhimurium, facilitates uptake of hydrogen peroxide (h₂o₂) and that its expression is negatively regulated by arca upon peroxide exposure. when exposed to sublethal concentrations of h₂o₂, a s. typhimurium ompd mutant showed decreased peroxide levels compared to those observed in the wild type strain, suggesting that h₂o₂ could be channeled inside the cell through ompd. further evidence came from in vitro stud ...201021144897
the interaction dynamics of a negative feedback loop regulates flagellar number in salmonella enterica serovar typhimurium.each salmonella enterica serovar typhimurium cell produces a discrete number of complete flagella. flagellar assembly responds to changes in growth rates through flhd(4) c(2) activity. flhd(4) c(2) activity is negatively regulated by the type 3 secretion chaperone flit. flit is known to interact with the flagellar filament cap protein flid as well as components of the flagellar type 3 secretion apparatus. flid is proposed to act as an anti-regulator, in a manner similar to flgm inhibition of σ(2 ...201021143315
dna topology of highly transcribed operons in salmonella enterica serovar typhimurium.bacteria differ from eukaryotes by having the enzyme dna gyrase, which catalyses the atp-dependent negative supercoiling of dna. negative supercoils are essential for condensing chromosomes into an interwound (plectonemic) and branched structure known as the nucleoid. topo-1 removes excess supercoiling in an atp-independent reaction and works with gyrase to establish a topological equilibrium where supercoils move within 10 kb domains bounded by stochastic barriers along the sequence. however, t ...201021143310
potential application of spice and herb extracts as natural preservatives in cheese.this study investigated the antibacterial efficiency of five spice and herb extracts (cinnamon stick, oregano, clove, pomegranate peel, and grape seed) against listeria monocytogenes, staphylococcus aureus, and salmonella enterica in cheese at room temperature (∼23°c). the lipid oxidation (thiobarbituric acid-reactive substances) of cheese was periodically tested by oxidative analyses. the results showed that all five plant extracts were effective against three foodborne pathogens in cheese. tre ...201021142945
epidemiology of plasmid-mediated quinolone resistance in salmonella enterica serovar typhimurium isolates from food-producing animals in japan.abstract: a total of 225 isolates of salmonella enterica serovar typhimurium from food-producing animals collected between 2003 and 2007 were examined for the prevalence of plasmid-mediated quinolone resistance (pmqr) determinants, namely qnra, qnrb, qnrc, qnrd, qnrs, qepa and aac(6')ib-cr, in japan. two isolates (0.8%) of s. typhimurium dt104 from different dairy cows on a single farm in 2006 and 2007 were found to have qnrs1 on a plasmid of approximately 9.6-kbp. none of the s. typhimurium iso ...201021138594
s. typhimurium ssej gene decreases the s. typhi cytotoxicity toward cultured epithelial cells.salmonella enterica serovar typhi and typhimurium are closely related serovars as indicated by >96% dna sequence identity between shared genes. nevertheless, s. typhi is a strictly human-specific pathogen causing a systemic disease, typhoid fever. in contrast, s. typhimurium is a broad host range pathogen causing only a self-limited gastroenteritis in immunocompetent humans. we hypothesize that these differences have arisen because some genes are unique to each serovar either gained by horizonta ...201021138562
separation and detection of multiple pathogens in a food matrix by magnetic sers nanoprobes.a rapid and sensitive method was developed here for separation and detection of multiple pathogens in food matrix by magnetic surface-enhanced raman scattering (sers) nanoprobes. silica-coated magnetic probes (mnps@sio(2)) of ~100 nm in diameter were first prepared via the reverse microemulsion method using cetyltrimethylammonium bromide as a surfactant and tetraethyl orthosilicate as the silica precursor. the as-prepared mnps@sio(2) were functionalized with specific pathogen antibodies to first ...201021136046
plasticity in the purine-thiamine metabolic network of salmonella.in salmonella enterica, 5-aminoimidazole ribonucleotide (air) is the precursor of the 4-amino-5-hydroxymethyl-2-methylpyrimidine (hmp) pyrophosphate moiety of thiamine and the last intermediate in the common hmp/purine biosynthetic pathway. air is synthesized de novo via five reactions catalyzed by the purf, -d, -t, -g, and -i gene products. in vivo genetic analysis demonstrated that in the absence of these gene products air can be generated if (i) methionine and lysine are in the growth medium, ...201021135073
prevalence of salmonella enterica and listeria monocytogenes contamination in foods of animal origin in italy.the present survey collected and analyzed the results of routine testing for salmonella enterica and listeria monocytogenes on foods of animal origin submitted for official controls in italy during 2001 to 2002. salmonella was detected in 2.2% of 71,643 food samples examined, and the isolation rates ranged from 9.9% for raw poultry meat to less than 0.1% for dairy products. isolation rates were also high in raw pork (4.9%) and processed meats (5.3%), which often involved pork. low rates were obs ...200521132987
resting pigs on transport trailers as an intervention strategy to reduce salmonella enterica prevalence at slaughter.recent research has shown that much preharvest salmonella enterica infection in pigs occurs immediately before slaughter during this rest period in the contaminated abattoir holding pens. the objective of this study was to evaluate a potential intervention strategy to reduce the prevalence of s. enterica-positive pigs at slaughter, which consisted of resting pigs prior to slaughter on their transport vehicle, instead of in the abattoir holding pen. additionally, the effect of transportation of p ...200521132985
development of pcr primers for the detection of salmonella enterica serovar choleraesuis based on the flic gene.salmonella enterica serovar choleraesuis may cause swine salmonellosis and human infection. because the conventional method for detection of this salmonella serovar may take 3 to 5 days, a pcr method for detection was evaluated. by comparing the sequence of the phase 1 flagellin (flic) gene of salmonella choleraesuis with that of other salmonella serovars and of other bacteria species available in genbank, two pcr primers (flinc-f and flinc-r) were designed. using these primers, all 97 salmonell ...200521132962
antimicrobial resistance in generic escherichia coli isolates from wild small mammals living in swine farm, residential, landfill, and natural environments in southern ontario, canada.to assess the impacts of different types of human activity on the development of resistant bacteria in the feces of wild small mammals, we compared the prevalences and patterns of antimicrobial resistance and resistance genes in generic escherichia coli and salmonella enterica isolates from fecal samples collected from wild small mammals living in four environments: swine farms, residential areas, landfills, and natural habitats. resistance to antimicrobials was observed in e. coli isolates from ...201021131524
induction of fatty acid composition modifications and tolerance to biocides in salmonella enterica serovar typhimurium by plant-derived terpenes.to enhance food safety and stability, the food industry tends to use natural antimicrobials such as plant-derived compounds as an attractive alternative to chemical preservatives. nonetheless, caution must be exercised in light of the potential for bacterial adaptation to these molecules, a phenomenon previously observed with other antimicrobials. the aim of this study was to characterize the adaptation of salmonella enterica serovar typhimurium to sublethal concentrations of four terpenes extra ...201021131520
pcr identification of salmonella serogroups based on specific targets obtained by comparative genomics.comparative genomic approaches provide abundant information to reveal the diversity among salmonella serogroups. in a local genomic sequence database, twenty-five salmonella whole genomic sequences were divided into 6 (a, b, c1, c2, d and others) serogroups for mining the dna fragments specific for serogroups a through d. for each serogroup, a reference sequence was selected and split into 1000-bp fragments in silico to align against all the other genomic sequences to obtain one or more serogrou ...201021131088
orally administered p22 phage tailspike protein reduces salmonella colonization in chickens: prospects of a novel therapy against bacterial infections.one of the major causes of morbidity and mortality in man and economically important animals is bacterial infections of the gastrointestinal (gi) tract. the emergence of difficult-to-treat infections, primarily caused by antibiotic resistant bacteria, demands for alternatives to antibiotic therapy. currently, one of the emerging therapeutic alternatives is the use of lytic bacteriophages. in an effort to exploit the target specificity and therapeutic potential of bacteriophages, we examined the ...201021124920
il-17a/f-signaling does not contribute to the initial phase of mucosal inflammation triggered by s. typhimurium.salmonella enterica subspecies 1 serovar typhimurium (s. typhimurium) causes diarrhea and acute inflammation of the intestinal mucosa. the pro-inflammatory cytokines il-17a and il-17f are strongly induced in the infected mucosa but their contribution in driving the tissue inflammation is not understood. we have used the streptomycin mouse model to analyze the role of il-17a and il-17f and their cognate receptor il-17ra in s. typhimurium enterocolitis. neutralization of il-17a and il-17f did not ...201021124903
a subtractively optimized dna microarray using non-sequenced genomic probes for the detection of food-borne pathogens.in this study, we present the successful detection of food-borne pathogens using randomly selected non-sequenced genomic dna probes-based dna microarray chips. three food-borne pathogens, staphylococcus aureus, salmonella enterica subsp. enterica serovar typhimurium (s. typhimurium), and bacillus cereus, were subjected for the preparation of the dna microarray probes. initially, about 50 dna probes selected randomly from non-sequenced genomic dna of each pathogen were prepared by using a set of ...201021116735
immunization with salmonella enterica serovar typhimurium-derived outer membrane vesicles delivering the pneumococcal protein pspa confers protection against challenge with streptococcus pneumoniae.gram-negative bacteria produce outer membrane vesicles (omvs) that serve a variety of functions related to survival and pathogenicity. periplasmic and outer membrane proteins are naturally captured during vesicle formation. this property has been exploited as a method to derive immunogenic vesicle preparations for use as vaccines. in this work, we constructed a salmonella enterica serovar typhimurium strain that synthesized a derivative of the pneumococcal protein pspa engineered to be secreted ...201021115718
chronic and acute infection of the gall bladder by salmonella typhi: understanding the carrier state.despite major treatment and prevention efforts, millions of new typhoid infections occur worldwide each year. for a subset of infected individuals, salmonella enterica subsp. enterica serovar typhi colonizes the gall bladder and remains there long after symptoms subside, serving as a reservoir for the further spread of the disease. in this progress article, we explore recent advances in our understanding of the mechanisms by which salmonella spp.--predominantly s. typhi--colonize and persist in ...201021113180
gram negative shuttle bac vector for heterologous expression of metagenomic libraries.bacterial artificial chromosome (bac) vectors enable stable cloning of large dna fragments from single genomes or microbial assemblages. a novel shuttle bac vector was constructed that permits replication of bac clones in diverse gram-negative species. the "gram-negative shuttle bac" vector (pgns-bac) uses the f replicon for stable single-copy replication in e. coli and the broad-host-range rk2 mini-replicon for high-copy replication in diverse gram-negative bacteria. as with other bac vectors c ...201021112378
differential identification of salmonella enterica subsp. enterica serovar gallinarum biovars gallinarum and pullorum based on polymorphic regions of glgc and spec genes.salmonella enterica subsp. enterica serovar gallinarum biovars gallinarum and pullorum cause fowl typhoid and pullorum disease in avian species, respectively, and have been of considerable economic importance to the poultry industry in parts of the world. the definitive diagnosis of these diseases can be made only by isolation and identification of the causative agent. however, rapid identification of biovars gallinarum and pullorum is not easily feasible due to their common antigenic structure ...201021111918
analysis of psc138, the multidrug resistance plasmid of salmonella enterica serotype choleraesuis sc-b67.salmonella enterica serotype choleraesuis (s. choleraesuis) usually causes systemic infections in man and needs antimicrobial treatment. multidrug resistance (mdr) in s. choleraesuis is thus a great concern in the treatment of systemic non-typhoid salmonellosis. a large plasmid, psc138, was identified in 2002 from a s. choleraesuis strain sc-b67 that was resistant to all antimicrobial agents commonly used to treat salmonellosis, including ciprofloxacin and ceftriaxone. complete dna sequence of t ...201021111756
inactivation of cronobacter sakazakii by ultrasonic waves under pressure in buffer and foods.the objective of this research was to characterize the resistance of cronobacter sakazakii to ultrasonic waves under pressure (manosonication, ms). the d(ms) value (decimal reduction time value) of c. sakazakii in standard conditions (35°c, 117 μm, 200 kpa, citrate-phosphate buffer ph 7.0) was 0.41 min. this value was higher than that of yersinia enterocolitica (d(ms)=0.19 min) and lower than those of salmonella enterica serovar enteritidis (d(ms)=0.61 min), listeria monocytogenes (d(ms)=0.86 mi ...201021111503
an externally modulated, noise-driven switch for the regulation of spi1 in salmonella enterica serovar typhimurium.in this work we consider the regulation system present on the spi1 pathogenicity island of salmonella enterica serovar typhimurium. it is well-known that hila is the central regulator in the overall scheme of spi1 regulation and directly binds to virulence operons and activates their expression. the regulation of the expression of hila is via a complex feed-forward loop involving three transcriptional activators: hilc, hild and rtsa, and the negative regulator hile. our aim is to model this regu ...201021107576
[typhoid fever: facing the challenge of resistant strains].the introduction of chloramphenicol in 1948 revolutionised the outcome of typhoid fever but chloramphenicol-resistant strains of salmonella enterica serotype typhi were reported just two years later. resistance followed also the introduction of ampicillin and co-trimoxazole. during the second half of the 1980s, strains resistant to the three first-line antimicrobial agents, chloramphenicol, ampicillin and co-trimoxazole emerged and spread rapidly throughout the indian subcontinent and south east ...201021106179
mlva and phage typing as complementary tools in the epidemiological investigation of salmonella enterica serovar typhimurium clusters.in south australia serotyping and phage typing are employed for routine salmonella surveillance. molecular techniques such as multiple-locus variable number tandem repeat analysis (mlva) are increasingly utilized to aid outbreak investigations. during 2007 three salmonella enterica serovar typhimurium outbreaks involving phage types dt9, dt29, and dt44 were investigated. human, food and environmental isolates were also typed by mlva. in the dt9 outbreak cluster mlva demonstrated distinct groupin ...201021104081
modulation of salmonella gene expression by subinhibitory concentrations of quinolones.approximately 2.7% of a collection of salmonella enterica var. typhimurium promoter-lux reporter strains showed altered transcriptional patterns when exposed to low concentrations of nine different fluoroquinolones (fqs). even at the subinhibitory concentrations employed, all nine fqs upregulated genes involved in the sos response, umud, lexa, sbmc and dinp. in addition, transcriptional regulators, genes putatively associated with membrane integrity (spr), virulence (sica) and metabolism (plsb) ...201021102598
bactericidal activity of mouse α-defensin cryptdin-4 predominantly affects noncommensal bacteria.mouse paneth cell α-defensins, termed cryptdins, are secreted into the intestinal lumen, have microbicidal activity, and contribute to intestinal innate immunity. among them, cryptdin-4 (crp4) has the most potent microbicidal activity. in the intestinal lumen, commensal bacteria colonize and elicit beneficial effects in the host. however, the effects of crp4 against commensal bacteria are poorly understood. thus, we investigated the bactericidal activities of crp4 against commensal bacteria comp ...201021099205
high prevalence of integron-mediated resistance in clinical isolates of salmonella enterica.salmonella enterica has become progressively resistant to antimicrobial agents worldwide as a result of genes carried on different classes of integrons. the aim of the current study was to investigate the molecular diversity of these integrons and their association with antimicrobial resistance in clinical s. enterica isolates from tehran, iran. antimicrobial susceptibility testing was performed according to the clinical and laboratory standards institute. the presence of integrons was investiga ...201021099092
use of inverse pcr for analysis of class 1 integrons carrying an unusual 3' conserved segment structure.by using inverse pcr and dna sequencing, 13 sul3-associated mutational integrons, 2 defective class 1 integrons, and 1 qnrb2-associated complex sul1-type class 1 integrons were identified in salmonella enterica serovar choleraesuis, pseudomonas aeruginosa, and enterobacter cloacae, respectively. in addition, conjugation and southern hybridization demonstrated that unusual class 1 integrons were located on plasmids or integrated into chromosomal dna. thus, an inverse pcr assay can be a valuable t ...201021098251
whole-genome analysis of salmonella enterica serovar typhimurium t000240 reveals the acquisition of a genomic island involved in multidrug resistance via is1 derivatives on the chromosome.salmonella enterica serovar typhimurium is frequently associated with life-threatening systemic infections, and the recent global emergence of multidrug resistance in s. enterica isolates from agricultural and clinical settings has raised concerns. in this study, we determined the whole-genome sequence of fluoroquinolone-resistant s. enterica serovar typhimurium t000240 strain (dt12) isolated from human gastroenteritis in 2000. comparative genome analysis revealed that t000240 displays high sequ ...201021098248
the vi capsular polysaccharide prevents complement receptor 3-mediated clearance of salmonella enterica serotype typhi.capsular polysaccharides are important virulence factors of invasive bacterial pathogens. here we studied the role of the virulence (vi) capsular polysaccharide of salmonella enterica serotype typhi (s. typhi) in preventing innate immune recognition by complement. comparison of capsulated s. typhi with a noncapsulated mutant (δtvibcde vexabcde mutant) revealed that the vi capsule interfered with complement component 3 (c3) deposition. decreased complement fixation resulted in reduced bacterial b ...201021098104
enhanced virulence of salmonella enterica serovar typhimurium after passage through mice.the interaction between salmonella enterica and the host immune system is complex. the outcome of an infection is the result of a balance between the in vivo environment where the bacteria survive and grow and the regulation of fitness genes at a level sufficient for the bacteria to retain their characteristic rate of growth in a given host. using bacteriological counts from tissue homogenates and fluorescence microscopy to determine the spread, localization, and distribution of s. enterica in t ...201021098099
a novel salmonella typhi-based immunotherapy promotes tumor killing via an antitumor th1-type cellular immune response and neutrophil activation in a mouse model of breast cancer.we investigated the use of a live, attenuated salmonella enterica serovar typhi vaccine strain as an antitumor immunotherapy. mice bearing a subcutaneous tumor (lm3 mammary adenocarcinoma) were immunized on three occasions with s. typhi strain cvd 915 by injection into the tumor, the peritumoral tissue and the draining lymph node areas; this procedure was termed salmonella multiple treatment (salmonella mt). tumor-bearing mice subjected to the salmonella mt exhibited reduced tumor growth, prolon ...201021095252
effect of resveratrol and quercetin in experimental infection by salmonella enterica serovar typhimurium.flavonoids are phenolic compounds widely distributed in almost every plant and act as pharmacologically active constituents in many herbal medicines. they have multiple biological, pharmacological, and medicinal properties including anti-inflammatory and cytoprotective effects. in the present study, the experiments were performed to evaluate the effect of resveratrol and quercetin on proliferation, viability, nitric oxide (no) production, and apoptosis in salmonella enterica serovar typhimurium- ...201021093605
[antibiotic susceptibility of salmonella enterica serovar typhi isolated from blood cultures at the ain m'lila hospital (algeria), between 2005 and 2008].typhoid fever is a food- and water-borne disease, caused by salmonella enterica serovar typhi, responsible for high rates of morbidity and mortality in developing countries. typhoid is also a public health problem in algeria. antimicrobial susceptibility surveillance must be applied to prevent the emergence of multidrug resistant strains.201021093188
a multiplex ligation detection assay for the characterization of salmonella enterica strains.a proof of principle of a multi-target assay for genotyping salmonella has been developed targeting 62 genomic marker sequences of salmonella related to pathogenicity. the assay is based on multiplex ligation detection reaction (ldr) followed by customized arraytube® microarray detection. the feasibility of the developed assay was verified in a method comparison study with conventional pcr using 16 salmonella 'test' strains comprising eight serovars. subsequently, the feasibility of the ldr micr ...201021093086
low endotoxic activity of lipopolysaccharides isolated from bradyrhizobium, mesorhizobium, and azospirillum strains.the endotoxic activities of lipopolysaccharides (lps) isolated from different strains of rhizobia and rhizobacteria (bradyrhizobium, mesorhizobium, and azospirillum) were compared to those of salmonella enterica sv. typhimurium lps. the biological activity of all the examined preparations, measured as limulus lysate gelation, production of tumor necrosis factor (tnf), interleukin-1β (il-1β), and interleukin-6 (il-6), and nitrogen oxide (no) induction in human myelomonocytic cells (line thp-1), w ...201021091983
charged residues in the cytoplasmic loop of mota are required for stator assembly into the bacterial flagellar motor.mota and motb form a transmembrane proton channel that acts as the stator of the bacterial flagellar motor to couple proton flow with torque generation. the c-terminal periplasmic domain of motb plays a role in anchoring the stators to the motor. however, it remains unclear where their initial binding sites are. here, we constructed salmonella strains expressing gfp-motb and mota-mcherry and investigated their subcellular localization by fluorescence microscopy. neither the d33n and d33a mutatio ...201021091499
insights into the mechanism of type i dehydroquinate dehydratases from structures of reaction intermediates.the biosynthetic shikimate pathway consists of seven enzymes that catalyze sequential reactions to generate chorismate, a critical branch point in the synthesis of the aromatic amino acids. the third enzyme in the pathway, dehydroquinate dehydratase (dhqd), catalyzes the dehydration of 3-dehydroquinate to 3-dehydroshikimate. we present three crystal structures of the type i dhqd from the intestinal pathogens clostridium difficile and salmonella enterica. structures of the enzyme with substrate a ...201021087925
the burden and characteristics of enteric fever at a healthcare facility in a densely populated area of kathmandu.enteric fever, caused by salmonella enterica serovars typhi and paratyphi a (s. typhi and s. paratyphi a) remains a major public health problem in many settings. the disease is limited to locations with poor sanitation which facilitates the transmission of the infecting organisms. efficacious and inexpensive vaccines are available for s. typhi, yet are not commonly deployed to control the disease. lack of vaccination is due partly to uncertainty of the disease burden arising from a paucity of ep ...201021085575
environmental sampling for salmonellaspp. in colorado animal shelters.salmonella enterica is an important zoonotic agent and nosocomial infections and epidemics have occurred in animal facilities. the objective of this study was to estimate the prevalence of salmonella in the environment in animal shelters. from 12 to 25 samples were taken from each shelter to represent environmental contamination. samples were collected from surfaces in areas used by animals and in public access areas including animal receiving rooms, kennels, paediatric wards, treatment, visitat ...201021083828
roles of salmonella multidrug efflux pumps in tigecycline resistance.salmonella enterica strains exhibiting decreased susceptibility to tigecycline have been reported. in this study, we sought to elucidate the roles of salmonella multidrug efflux pumps and acrab regulators in tigecycline resistance.201021081542
the ubiquitin-binding adaptor proteins p62/sqstm1 and ndp52 are recruited independently to bacteria-associated microdomains to target salmonella to the autophagy pathway. 201121079414
characterization of avian γδ t-cell subsets after salmonella enterica serovar typhimurium infection of chicks.avian γδ t lymphocytes are frequently found in blood and organs and are assumed to be crucial to the immune defense against salmonella infections of chicks. to elucidate the so-far-unknown immunological features of subpopulations of avian γδ t cells in the course of infection, day-old chicks were infected orally with salmonella enterica serovar typhimurium. until 11 days after infection, the occurrence as well as transcription of the cd8 antigen and immunologically relevant protein genes of cd8α ...201021078853
comparison of microbial diversity of edible flowers and basil grown with organic versus conventional methods.the consumption and use of edible flowers as food is growing; however, no study has been conducted to evaluate their role in the cause of food-borne illness or in food safety. recent food-borne outbreaks traced to fresh herbs have raised concern about their processing and handling. basil, one of the most commonly used fresh herbs, has been identified as a source of food-borne illness. baseline assessments of microflora were performed, and the microbial diversity between growing methods (organic ...201021076485
opposing contributions of polynucleotide phosphorylase and the membrane protein nlpi to biofilm formation by salmonella enterica serovar typhimurium.csgd and cyclic-3',5'-di-guanylate are key regulators of biofilm formation in salmonella enterica serovar typhimurium. our results show that polynucleotide phosphorylase and nlpi oppositely altered expression of csgd. polynucleotide phosphorylase and nlpi also had opposite effects on the expression of yjcc, which codes for a cyclic-3',5'-di-guanylate phosphodiesterase affecting csgd expression.201021075929
fur negatively regulates hns and is required for the expression of hila and virulence in salmonella enterica serovar typhimurium.iron is an essential element for the survival of living cells. however, excess iron is toxic, and its uptake is exquisitely regulated by the ferric uptake regulator, fur. in salmonella, the salmonella pathogenicity island 1 (spi-1) encodes a type three secretion system, which is required for invasion of host epithelial cells in the small intestine. a major activator of spi-1 is hila, which is encoded within spi-1. one known regulator of hila is fur. the mechanism of hila regulation by fur is unk ...201021075923
colonization of tomato plants by salmonella enterica is cultivar dependent, and type 1 trichomes are preferred colonization sites.nontyphoid salmonellosis caused by salmonella enterica is the most common bacterial food-borne illness in humans, and fresh produce, including tomatoes, is a common vehicle. accumulating data indicate that human enteric pathogenic bacteria, including s. enterica, interact actively with plants. tomato plants were inoculated with s. enterica to evaluate plausible contamination routes and to determine if the tomato cultivar affects s. enterica colonization. s. enterica population levels on tomato l ...201021075871
inhibition of efflux pumps in methicillin-resistant staphylococcus aureus and enterococcus faecalis resistant strains by triterpenoids from momordica balsamina.six cucurbitane-type triterpenoids (1-6) isolated from the aerial parts of momordica balsamina were evaluated for their ability to inhibit the activity of bacterial efflux pumps of methicillin-resistant staphylococcus aureus (mrsa) col(oxa), enterococcus faecalis atcc 29212, salmonella enterica subsp. i serovar typhimurium 5408 and s. typhimurium 5408cip strains. the latter strain overproduces the acrb transporter of the acrab-tolc efflux pump six-fold compared with its parent. compounds 4-6 wer ...201021075604
different sugar residues of the lipopolysaccharide outer core are required for early interactions of salmonella enterica serovars typhi and typhimurium with epithelial cells.the role of lipopolysaccharide (lps) in entry of salmonella typhimurium into epithelial cells remains unclear. in this study, we tested the ability of a series of mutants with deletions in genes for the synthesis and assembly of the o antigen and the outer core of lps to adhere to and invade hela, bhk, and ib3 epithelial cells lines. mutants devoid of o antigen, or that synthesized only one o antigen unit, or with altered o antigen chain lengths were as able as the wild type to enter epithelial ...201021075194
persistence and spread of salmonella enterica serovar weltevreden in soil and on spinach plants.several outbreaks caused by pathogenic bacteria are related to the consumption of raw produce contaminated by animal manure. the majority of these outbreaks have been linked to salmonella spp. we examined the ability of salmonella enterica serovar weltevreden to persist and survive in manure and soil as well as disseminate to, and persist on, spinach roots and leaves. significantly higher numbers of s. weltevreden inoculated into manure and applied to soil before planting spinach were found in s ...201021073511
salmonella genomic islands and antibiotic resistance in salmonella enterica.antibiotic resistance in several salmonella enterica serovars that cause gastrointestinal disease in humans is due to a set of related genomic islands carrying a class 1 integron, which carries the resistance genes. salmonella genomic island 1 (sgi1), the first island of this type, was found in s. enterica serovar typhimurium dt104 isolates, which are resistant to ampicillin, chloramphenicol, florfenicol, streptomycin, spectinomycin, sulfonamides and tetracycline. several salmonella serovars and ...201021073312
status of vi gene, its expression and salmonella pathogenicity island (spi-7) in salmonella typhi in india.salmonella enterica serotype typhi (s. typhi) is a causative organism of typhoid fever. a number of salmonella serovars express a capsular polysaccharide antigen known as vi, the biosynthetic and export proteins of which are encoded within the viab locus of salmonella pathogenicity island -7 (spi-7). spi-7 is inserted between two partially duplicated copies of trna -pheu gene. we have investigated the frequency of viab operon deletion and loss of spi-7 due to storage of strains collected during ...201021073066
evaluation and target validation of indole derivatives as inhibitors of the acrab-tolc efflux pump.indole derivatives 3-amino-6-carboxyl-indole and 3-nitro-6-amino-indole were designed and synthesized based on the tolc structure. they proved to have potent synergistic antibacterial effects on chloramphenicol, tetracycline, erythromycin, and ciprofloxacin against escherichia coli yd2 and fj307 with decreased minimal inhibitory concentrations (mics) at 2-64 folds. to research its functional site, escherichia coli bl21(de3)-3 expressing a target-site mutated tolc was constructed by red homologou ...201021071837
cell-free fusion of bacteria-containing phagosomes with endocytic compartments.uptake of microorganisms by professional phagocytic cells leads to formation of a new subcellular compartment, the phagosome, which matures by sequential fusion with early and late endocytic compartments, resulting in oxidative and nonoxidative killing of the enclosed microbe. few tools are available to study membrane fusion between phagocytic and late endocytic compartments in general and with pathogen-containing phagosomes in particular. we have developed and applied a fluorescence microscopy ...201021071675
multiplication of salmonella enteritidis in egg yolks after inoculation outside, on, and inside vitelline membranes and storage at different temperatures.prompt refrigeration to restrict bacterial growth is important for reducing eggborne transmission of salmonella enterica serovar enteritidis (se). the nutrient-rich yolk interior is a relatively infrequent location for initial se deposition in eggs, but migration across the vitelline membrane can result in rapid bacterial multiplication during storage at warm temperatures. the objective of the present study was to measure the multiplication of se in yolks after introduction at three different lo ...201021067679
quantitative microbial risk assessment for escherichia coli o157:h7, salmonella enterica, and listeria monocytogenes in leafy green vegetables consumed at salad bars, based on modeling supply chain logistics.quantitative microbial risk assessments do not usually account for the planning and ordering mechanisms (logistics) of a food supply chain. these mechanisms and consumer demand determine the storage and delay times of products. the aim of this study was to quantitatively assess the difference between simulating supply chain logistics (mod) and assuming fixed storage times (fix) in microbial risk estimation for the supply chain of fresh-cut leafy green vegetables destined for working-canteen sala ...201021067671
fates of foodborne pathogens in raw hams manufactured rapidly using a new patented method.to manufacture raw ham in an efficient manner, we recently developed a new system in which presliced pork loin was used, and the processing time was reduced to 5% of the conventional method. this study aimed to examine whether this raw ham could be as safe as ham produced by the conventional method. pork loin spiked with enterohemorrhagic escherichia coli serotype o157:h7, listeria monocytogenes serotype 1/2c, salmonella enterica serovar enteritidis, and staphylococcus aureus were processed usin ...201021067667
characterization of a novel salmonella typhimurium chitinase which hydrolyzes chitin, chitooligosaccharides and an n-acetyllactosamine conjugate.salmonella contain genes annotated as chitinases; however, their chitinolytic activities have never been verified. we now demonstrate such an activity for a chitinase assigned to glycoside hydrolase family 18 encoded by the sl0018 (chia) gene in salmonella enterica typhimurium sl1344. a c-terminal truncated form of chia lacking a putative chitin-binding domain was amplified by pcr, cloned and expressed in escherichia coli bl21 (de3) with an n-terminal (his)(6) tag. the purified enzyme hydrolyzes ...201021062783
[antibacterial antibodies in human immunoglobulins and sera: past and present].to measure levels of several types of antibacterial antibodies in preparations of normal human immunoglobulin as well as in samples of donor sera obtained in 1965 and 2009.201021061576
re-emergence of multi-drug resistant salmonella enterica serovar stanley from cattle.during 2009, salmonella enterica subspecies enterica serovar stanley isolates were recovered from cattle diagnostic specimens in southern japan, and the isolates were examined to characterize the genetic determinants involved in this new pathogenicity that associated with mortality in cattle. all the isolates were multi-drug resistance exhibited resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, oxytetracycline, and kanamycin (acssut-km) encoded by blatem, cata, aada1, su ...201121061061
salmonella enterica response regulator ssrb relieves h-ns silencing by displacing h-ns bound in polymerization mode and directly activates transcription.the response regulator ssrb activates expression of genes encoded within and outside of a pathogenicity island (spi-2), which is required for systemic infection of salmonella. ssrb binds upstream of the sifa, sifb, and ssej effector genes and directly regulates transcription. ssrb also relieves gene silencing by the nucleoid protein h-ns. single molecule experiments with magnetic tweezers demonstrated that ssrb displaces h-ns from dna only when it is bound in a polymerization (stiffening) mode a ...201021059643
protective effect of lactobacillus casei strain shirota against lethal infection with multi-drug resistant salmonella enterica serovar typhimurium dt104 in mice.the anti-infectious activity of lactobacilli against multi-drug resistant salmonella enterica serovar typhimurium dt104 (dt104) was examined in a murine model of an opportunistic antibiotic-induced infection.201021059159
membrane tubules attach salmonella typhimurium to eukaryotic cells and bacteria.using scanning electron microscopy techniques we measured the diameter of adhesive tubular appendages of salmonella enterica serovar s. typhimurium. the appendages interconnected bacteria in biofilms grown on gallstones or coverslips, or attached bacteria to host cells (human neutrophils). the tubular appendage diameter of bacteria of virulent flagellated c53 strain varied between 60 and 70 nm, thus considerably exceeding in size of flagella or pili. nonflagellated bacteria of mutant sjw 880 str ...201021054581
salmonella enterica serovar typhi and s. paratyphi a: need to expand the qrdr region? 201021050501
immune response induced by ppgpp-defective salmonella enterica serovar gallinarum in chickens.to protect chickens from typhoid caused by salmonella enterica serovar gallinarum (s. gallinarum), the attenuated 9r strain has been used in the field as a vaccine. however, safety concerns have been raised because the mutations in 9r are undefined while its efficacy is still a question under debate. a global regulator, ppgpp, synthesized by rela and spot, has been shown to induce various virulence genes in s. gallinarum (jeong et al., 2008). in this study, two mutant strains defective in ppgpp- ...201021046347
molecular cloning and characterization of clya genes in various serotypes of salmonella enterica.cytolysin a (clya) is a pore-forming hemolytic protein encoded by the clya gene. it has been identified in salmonella enterica serovars typhi and paratyphi a. to identify and characterize the clya genes in various salmonella enterica strains, 21 different serotypes of strains isolated from clinical specimens were presently examined. full-length clya genes were found in s. enterica serovar brandenburg, indiana, panama, and schwarzengrund strains by polymerase chain reaction amplification. the cly ...201021046345
distribution of pathogenicity islands among colombian isolates of salmonella.salmonella pathogenicity islands (spis) are regions scattered along the bacterial chromosome, with an acknowledged pivotal role during gastrointestinal and systemic infection. the distribution of spis has been investigated in reference strains. however, there is a lack of studies on their presence and/or assortment within the genomes of salmonella enterica (s. enterica) serovars that circulate in different geographical regions. therefore, in this study, we aimed to determine the presence of gene ...201021045367
crystallization and preliminary crystallographic analysis of the type iii secretion translocator chaperone sica from salmonella enterica.sica is a member of the class ii chaperones in type iii secretion systems which bind to the pore-forming translocators in the bacterial cytoplasm and prevent them from premature association and degradation. in this study, sica from salmonella enterica serovar typhimurium was overexpressed, purified and crystallized using peg 8000 as the precipitant. x-ray diffraction data were collected using synchrotron radiation and processed at 3.5 å resolution. the crystal belonged to the monoclinic space gr ...201021045315
the structural characterization of the o-polysaccharide antigen of the lipopolysaccharide of escherichiacoli serotype o118 and its relation to the o-antigens of escherichiacoli o151 and salmonellaenterica o47.mild acid hydrolysis of the lipopolysaccharide produced by escherichiacoli o118:h16 standard strain (nrcc 6613) afforded an o-polysaccharide (o-ps) composed of d-galactose, 2-acetamidoylamino-2,6-dideoxy-l-galactose, 2-acetamido-2-deoxy-d-glucose, ribitol, and phosphate (1:1:1:1:1). from doc-page, sugar and methylation analyses, one- and two-dimensional nmr spectroscopy, capillary electrophoresis-mass spectrometry, hydrolysis, and sequential smith-type periodate oxidation studies, the o-ps was d ...201021044779
the small regulatory rna molecule mica is involved in salmonella enterica serovar typhimurium biofilm formation.luxs is the synthase enzyme of the quorum sensing signal ai-2. in salmonella typhimurium, it was previously shown that a luxs deletion mutant is impaired in biofilm formation. however, this phenotype could not be complemented by extracellular addition of quorum sensing signal molecules.201021044338
micro ecosystems from feed industry surfaces: a survival and biofilm study of salmonella versus host resident flora strains.the presence of salmonella enterica serovars in feed ingredients, products and processing facilities is a well recognized problem worldwide. in norwegian feed factories, strict control measures are implemented to avoid establishment and spreading of salmonella throughout the processing chain. there is limited knowledge on the presence and survival of the resident microflora in feed production plants. information on interactions between salmonella and other bacteria in feed production plants and ...201021044298
conjugates of bovine serum albumin with chitin oligosaccharides prepared through the maillard reaction.chitin neoglycoconjugates (bsa-co) were obtained by the conjugation of bovine serum albumin (bsa) with chitin oligosaccharides (co) through the maillard reaction (nonenzymatic glycation). co produced by acid hydrolysis of chitin were fractionated using an ultrafiltration membrane system (1-3 kda cutoff). the maillard reaction was carried out by heating a freeze-dried mixture containing bsa and co at 60 °c (under 43% relative humidity for 6 and 12 h). bsa-co were characterized by available amino ...201021043451
enteric pathology and salmonella-induced cell death in healthy and siv-infected rhesus macaques.the goal of this study was to morphologically characterize a ligated ileal loop model of salmonella enterica serotype typhimurium infection in rhesus macaques (macaca mulatta) and to verify the occurrence of salmonella-induced cell death in vivo. eight adult healthy male rhesus macaques were used for ligated ileal loop surgery. four macaques had been intravenously inoculated with simian immunodeficiency virus (siv) mac251. ileal ligated loops were inoculated with wild-type (wt) s. typhimurium st ...201021041540
quantitative pcr-based competitive index for high-throughput screening of salmonella virulence factors.salmonella enterica serovar typhimurium is an intracellular pathogen and a main cause of food-borne illness. in this study, a quantitative pcr (qpcr)-based competitive index (ci) method was developed to simultaneously compare the growth of multiple salmonella strains. this method was applied to a mixture of 17 salmonella mutants lacking regulator genes, and their survival ratios were compared based on expression of natural resistance-associated macrophage protein 1 (nramp1). nramp1, as a major h ...201021041489
loop-mediated isothermal amplification assay targeting the ompa gene for rapid detection of riemerella anatipestifer.a novel loop-mediated isothermal amplification (lamp) assay was developed and evaluated for the detection of riemerella anatipestifer (ra) infection. the lamp assay exhibited a higher sensitivity than conventional polymerase chain reaction (pcr) and microbial isolation. the specificity of the assay was determined by restriction enzyme digestion of the lamp products and detection of escherichia coli, salmonella enterica and pasteurella multocida. the lamp assay was able to detect ra effectively i ...201021040782
leaching of salmonella enterica in clay columns comparing two manure application methods.transfer of zoonotic bacterial pathogens through intact soil columns was monitored in an outdoor lysimeter over 36 d. manure spiked with salmonella enterica serovar senftenberg was applied to either the soil surface or injected 0.08 m into the soil to compare leaching associated with the two manure application methods. the highest concentrations of s. enterica (up to 60,000 s. enterica cfu/ml) were detected on day 1 in the first drainage samples, with measurable but declining concentrations pers ...201021039451
ethanolamine utilization contributes to proliferation of salmonella enterica serovar typhimurium in food and in nematodes.only three pathogenic bacterial species, salmonella enterica, clostridium perfringens, and listeria monocytogenes, are able to utilize both ethanolamine and 1,2-propanediol as a sole carbon source. degradation of these substrates, abundant in food and the gut, depends on cobalamin, which is synthesized de novo only under anaerobic conditions. although the eut, pdu, and cob-cbi gene clusters comprise 40 kb, the conditions under which they confer a selection advantage on these food-borne pathogens ...201021037291
inactivation of the rlud pseudouridine synthase has minimal effects on growth and ribosome function in wild-type escherichia coli and salmonella enterica.the escherichia coli rlud gene encodes a pseudouridine synthase responsible for the pseudouridine (ψ) modifications at positions 1911, 1915, and 1917 in helix 69 of 23s rrna. it has been reported that deletion of rlud in k-12 strains of e. coli is associated with extremely slow growth, increased readthrough of stop codons, and defects in 50s ribosomal subunit assembly and 30s-50s subunit association. suppressor mutations in the prfb and prfc genes encoding release factor 2 (rf2) and rf3 that res ...201021037010
roles of spvb and spvc in s. typhimurium colitis via the alternative pathway.salmonella enterica subspecies i serovar typhimurium (s. typhimurium) is a frequent cause of diarrhea worldwide. it employs 2 type iii secretion systems (ttss) to elicit mucosal inflammation via the ttss-1-dependent 'classical' or the ttss-2-dependent 'alternative' pathway. if ttss-1 is defective (in invg or invc mutants), the pathogen is confined to the alternative pathway; transits the epithelium in a dendritic cell-dependent fashion, relocalizes from cd11c(+) dendritic cells to cd11c(-) cells ...201021036103
influence of aerobic and anaerobic conditions on survival of escherichia coli o157:h7 and salmonella enterica serovar typhimurium in luria-bertani broth, farm-yard manure and slurry.the influence of aerobic and anaerobic conditions on the survival of the enteropathogens escherichia coli o157:h7 and salmonella serovar typhimurium was investigated in microcosms with broth, cattle manure or slurry. these substrates were inoculated with a green fluorescent protein transformed strain of the enteropathogens at 10(7) cells g(-1) dry weight. survival data was fitted to the weibull model. the survival curves in aerobic conditions generally showed a concave curvature, while the curva ...201021035246
effects of restricted antimicrobial exposure on antimicrobial resistance in fecal escherichia coli from feedlot cattle.the primary objective was to evaluate differences in antimicrobial resistance among enteric bacteria recovered from feedlot cattle that were being raised without exposure to antimicrobial drugs (amds) and those reared using conventional practices.201021034271
epidemiological investigation of salmonella enterica serovar kedougou in thailand.salmonella enterica serovar kedougou is among the top 10 serovars reported in northern thailand. the objective of this study was to identify risk factors associated with salmonella kedougou infection in thailand and to compare the molecular types and antimicrobial resistance with salmonella kedougou isolates of human origin from united states and of animal origin from the united kingdom.201021034262
eavesdropping by bacteria: the role of sdia in escherichia coli and salmonella enterica serovar typhimurium quorum sensing.many gram-negative bacteria utilize n-acyl-l-homoserine lactones (ahls) to bind to transcriptional regulators leading to activation or repression of target genes. escherichia coli and salmonella enterica do not synthesize ahls but do contain the ahl receptor, sdia. studies reveal that sdia can bind ahls produced by other bacterial species and thereby allow e. coli and s. enterica to regulate gene transcription. the salmonella sdia gene regulates the rck gene, which mediates salmonella adhesion a ...201021034261
salmonella enterica and escherichia coli harboring blacmy in retail beef and pork products.we estimated the proportion of retail beef and pork products containing bla(cmy)-mediated third-generation cephalosporin resistance in commensal escherichia coli and salmonella enterica. samples were obtained from 50 grocery stores located in two u.s. states. from each store, 20 fresh meat products were purchased, including 7 packages of ground beef, 3 packages of beef steak, 6 packages of pork chops, and 4 packages of pork ribs. the resulting 1000 packages of fresh meat product were individuall ...201021034230
label-free identification of bacterial microcolonies via elastic scattering.label-free microcolony identification via elastic light scattering was investigated for three different genera: salmonella enterica serovar montevideo, listeria monocytogenes f4244, and escherichia coli dh5α. microcolonies were defined as bacterial colonies in their late-lag phase to early-exponential phase with the diameter range of 100-200 µm. to link biophysical characteristics with corresponding scattering patterns, a phase contrast microscope and a confocal displacement meter were used to m ...201021031358
plasmid-mediated quinolone resistance among non-typhi salmonella enterica isolates, usa.we determined the prevalence of plasmid-mediated quinolone resistance mechanisms among non-typhi salmonella spp. isolated from humans, food animals, and retail meat in the united states in 2007. six isolates collected from humans harbored aac(6')ib-cr or a qnr gene. most prevalent was qnrs1. no animal or retail meat isolates harbored a plasmid-mediated mechanism.201021029547
multidrug-resistant salmonella enterica serovar infantis, israel.to determine whether rapid emergence of salmonella enterica serovar infantis in israel resulted from an increase in different biotypes or spread of 1 clone, we characterized 87 serovar infantis isolates on the genotypic and phenotypic levels. the emerging strain comprised 1 genetic clone with a distinct pulsed-field gel electrophoresis profile and a common antimicrobial drug resistance pattern.201021029536
salmonella enterica pulsed-field gel electrophoresis clusters, minnesota, usa, 2001-2007.we determined characteristics of salmonella enterica pulsed-field gel electrophoresis clusters that predict their being solved (i.e., that result in identification of a confirmed outbreak). clusters were investigated by the minnesota department of health by using a dynamic iterative model. during 2001-2007, a total of 43 (12.5%) of 344 clusters were solved. clusters of ≥4 isolates were more likely to be solved than clusters of 2 isolates. clusters in which the first 3 case isolates were received ...201021029524
salmonella choleraesuis (variety kunzendorf) bacteriemia complicating streptococcal sore throat. 194621023181
observations regarding salmonella choleraesuis (var. kunzendorf) septicemia in swine. 194620996650
simultaneous analysis of multiple enzymes increases accuracy of pulsed-field gel electrophoresis in assigning genetic relationships among homogeneous salmonella strains.due to a highly homogeneous genetic composition, the subtyping of salmonella enterica serovar enteritidis strains to an epidemiologically relevant level remains intangible for pulsed-field gel electrophoresis (pfge). we reported previously on a highly discriminatory pfge-based subtyping scheme for s. enterica serovar enteritidis that relies on a single combined cluster analysis of multiple restriction enzymes. however, the ability of a subtyping method to correctly infer genetic relatedness amon ...201020980570
enteric fever in a 6-year-old traveler caused by salmonella enterica serotypes typhi and paratyphi a: laboratory detection strategies and treatment options.we report the first pediatric case of enteric fever caused by salmonella enterica serotypes typhi and paratyphi a. mixed infections are infrequently reported, potentially because detection of two different salmonella serotypes in blood cultures is technically challenging. we suggest laboratory strategies to aid in the recognition of mixed infections.201020980563
recognition of heptameric seed sequence underlies multi-target regulation by rybb small rna in salmonella enterica.prokaryotic regulatory small rnas act by a conserved mechanism and yet display a stunning structural variability. in the present study, we used mutational analysis to dissect the functional anatomy of rybb, a σ(e)-dependent srna that regulates the synthesis of major porins in escherichia coli and salmonella. mutations in the chromosomal rybb locus that altered the expression of an ompc-lac fusion were identified. some of the mutations cluster within a seven-nucleotide segment at the 5' end of th ...201020979336
solution nmr structure of the plasmid-encoded fimbriae regulatory protein pefi from salmonella enterica serovar typhimurium. 201120979070
exploitation of the ubiquitin system by invading bacteria.a variety of bacterial intracellular pathogens target the host cell ubiquitin system during invasion, a process that involves transient but fundamental changes in the actin cytoskeleton and plasma membrane. these changes are induced by bacterial proteins, which can be surface associated, secreted or injected directly into the host cell. here, the invasion strategies of two extensively studied intracellular bacteria, salmonella enterica serovar typhimurium and listeria monocytogenes, are used to ...201020977569
chromosomal rearrangements formed by rrn recombination do not improve replichore balance in host-specific salmonella enterica serovars.most of the ∼2,600 serovars of salmonella enterica have a broad host range as well as a conserved gene order. in contrast, some salmonella serovars are host-specific and frequently exhibit large chromosomal rearrangements from recombination between rrn operons. one hypothesis explaining these rearrangements suggests that replichore imbalance introduced from horizontal transfer of pathogenicity islands and prophages drives chromosomal rearrangements in an attempt to improve balance.201020976060
discovery of novel secreted virulence factors from salmonella enterica serovar typhimurium by proteomic analysis of culture supernatants.salmonella enterica serovar typhimurium is a leading cause of acute gastroenteritis throughout the world. this pathogen has two type iii secretion systems (ttss) encoded in salmonella pathogenicity islands 1 and 2 (spi-1 and spi-2) that deliver virulence factors (effectors) to the host cell cytoplasm and are required for virulence. while many effectors have been identified and at least partially characterized, the full repertoire of effectors has not been catalogued. in this proteomic study, we ...201020974834
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