Exit of salmonellae from the intestinal lumen involves invasion of intestinal epithelial cells, and this invasion relies upon the production of a type III secretory apparatus and protein effector molecules (including prgH and its cotranscribed genes) from SPI-1. These secreted effector molecules mediate changes in host epithelial cells, causing them to ruffle and engulf the bacterium. Our previous work showed that the transcription of prgH, which is part of an operon encoding members of the SPI-1-encoded secretion apparatus, is repressed in the presence of bile. Based on this preliminary observation, in this work, we show that the interaction of serovar Typhimurium with bile dramatically affects its invasive ability by downregulating the transcription of invasion gene regulators, which results in a marked decrease in the transcription of SPI-1 genes involved in epithelial cell entry.. A complex set of transcriptional activators interact to regulate serovar Typhimurium invasion of epithelial ...
Fosmidomycin is a time-dependent nanomolar inhibitor of methylerythritol phosphate (MEP) synthase, which is the enzyme that catalyzes the first committed step in the MEP pathway to isoprenoids. Importantly, fosmidomycin is one of only a few MEP pathway-specific inhibitors that exhibits antimicrobial activity. Most inhibitors identified to date only exhibit activity against isolated pathway enzymes. The MEP pathway is the sole route to isoprenoids in many bacteria, yet has no human homologs. The development of inhibitors of this pathway holds promise as novel antimicrobial agents. Similarly, analyses of the bacterial response toward MEP pathway inhibitors provides valuable information toward the understanding of how emergent resistance may ultimately develop to this class of antibiotics. We have examined the transcriptional response of Salmonella enterica serovar typhimurium LT2 to sub-inhibitory concentrations of fosmidomycin via cDNA microarray and RT-PCR. Within the regulated genes identified by
Members of Salmonella enterica are frequently involved in egg and egg product related human food poisoning outbreaks worldwide. In Australia, Salmonella Typhimurium is frequently involved in egg and egg product related foodborne illness and Salmonella Mbandaka has also been found to be a contaminant of the layer farm environment. The ability possessed by Salmonella Enteritidis to colonise reproductive organs and contaminate developing eggs has been well described. However, there are few studies investigating this ability for Salmonella Typhimurium. The hypothesis of this study was that the Salmonella Typhimurium can colonise the gut for a prolonged period of time and that horizontal infection through feces is the main route of egg contamination. At 14 weeks of age hens were orally infected with either S. Typhimurium PT 9 or S. Typhimurium PT 9 and Salmonella Mbandaka. Salmonella shedding in feces and eggs was monitored for 15 weeks post infection. Egg shell surface and internal contents of eggs laid
TY - JOUR. T1 - RosE represses Std fimbrial expression in Salmonella enterica serotype Typhimurium. AU - Chessa, Daniela. AU - Winter, Maria G.. AU - Nuccio, Sean Paul. AU - Tükel, Çagla. AU - Baumler, Andreas J. PY - 2008/5. Y1 - 2008/5. N2 - The Salmonella enterica serotype Typhimurium (S. typhimurium) genome contains a large repertoire of putative fimbrial operons that remain poorly characterized because they are not expressed in vitro. In this study, insertions that induced expression of the putative stdABCD fimbrial operon were identified from a random bank of transposon mutants by screening with immuno-magnetic particles for ligand expression (SIMPLE). Transposon insertions upstream of csgC and lrhA or within dam, setB and STM4463 (renamed rosE) resulted in expression of StdA and its assembly into fimbrial filaments on the cell surface. RosE is a novel negative regulator of Std fimbrial expression as indicated by its repression of a std::lacZ reporter construct and by binding of the ...
1998) Characterisation of recently emerged multiple antibiotic-resistant Salmonella enterica serovar typhimurium DT104 and other multiresistant phage types from Danish pig ...
TY - JOUR. T1 - FimY of Salmonella enterica serovar Typhimurium functions as a DNA-binding protein and binds the fimZ promoter. AU - Wang, Ke Chuan. AU - Hsu, Yuan Hsun. AU - Huang, Yi Ning. AU - Lin, Jiunn Horng. AU - Yeh, Kuang Sheng. PY - 2014. Y1 - 2014. N2 - Salmonella enterica serovar Typhimurium produces type 1 fimbriae with binding specificity to mannose residues. Elements involved in fimbrial structural biosynthesis, transport, and regulation are encoded by the fim gene cluster. FimZ, FimY, FimW, STM0551, and an arginine transfer RNA (fimU) were previously demonstrated to regulate fimbrial expression. The amino acid sequences of the C-terminal portion of FimY revealed similarity with those of LuxR-like proteins. Electrophoretic mobility shift assays indicated that FimY possessed DNA-binding capacity and bound a 605-bp DNA fragment spanning the intergenic region between fimY and fimZ, while a FimY protein harboring a double mutation in the C-terminal helix-turn-helix region containing a ...
BioAssay record AID 532763 submitted by ChEMBL: Antimicrobial activity against Salmonella serovar Typhimurium SL1344 expressing ramA::aph mutant by broth dilution method in presence of chlorpromazine.
Invasive Salmonella typhimurium induces dramatic cytoskeletal changes on the membrane surface of mammalian epithelial cells and RAW264.7 macrophages as part of its entry mechanism. Noninvasive S. typhimurium strains are unable to induce this membrane ruffling. Invasive S. typhimurium strains invade RAW264.7 macrophages in 2 h with 7- to 10-fold higher levels than noninvasive strains. Invasive S. typhimurium and Salmonella typhi, independent of their ability to replicate intracellularly, are cytotoxic to RAW264.7 macrophages and, to a greater degree, to murine bone marrow-derived macrophages. Here, we show that the macrophage cytotoxicity mediated by invasive Salmonella is apoptosis, as shown by nuclear morphology, cytoplasmic vacuolization, and host cell DNA fragmentation. S. typhimurium that enter cells causing ruffles but are mutant for subsequent intracellular replication also initiate host cell apoptosis. Mutant S. typhimurium that are incapable of inducing host cell membrane ruffling fail ...
Invasive Salmonella typhimurium induces dramatic cytoskeletal changes on the membrane surface of mammalian epithelial cells and RAW264.7 macrophages as part of its entry mechanism. Noninvasive S. typhimurium strains are unable to induce this membrane ruffling. Invasive S. typhimurium strains invade RAW264.7 macrophages in 2 h with 7- to 10-fold higher levels than noninvasive strains. Invasive S. typhimurium and Salmonella typhi, independent of their ability to replicate intracellularly, are cytotoxic to RAW264.7 macrophages and, to a greater degree, to murine bone marrow-derived macrophages. Here, we show that the macrophage cytotoxicity mediated by invasive Salmonella is apoptosis, as shown by nuclear morphology, cytoplasmic vacuolization, and host cell DNA fragmentation. S. typhimurium that enter cells causing ruffles but are mutant for subsequent intracellular replication also initiate host cell apoptosis. Mutant S. typhimurium that are incapable of inducing host cell membrane ruffling fail ...
Whole-genome sequencing is rapidly replacing current molecular typing methods for surveillance purposes. Our study evaluates core-genome single-nucleotide polymorphism analysis for outbreak detection and linking of sources of Salmonella enterica serovar Typhimurium and its monophasic variants during a 7-month surveillance period in Denmark. We reanalyzed and defined 8 previously characterized outbreaks from the phylogenetic relatedness of the isolates, epidemiologic data, and food traceback investigations. All outbreaks were identified, and we were able to exclude unrelated and include additional related human cases. We were furthermore able to link possible food and veterinary sources to the outbreaks. Isolates clustered according to sequence types (STs) 19, 34, and 36. Our study shows that core-genome single-nucleotide polymorphism analysis is suitable for surveillance and outbreak investigation for Salmonella Typhimurium (ST19 and ST36), but whole genome-wide analysis may be required for the tight
Virulent Salmonella typhimurium strains differ from the attenuated laboratory strain LT2 at the rpoS locus. It was previously shown that the rpoS gene in strain LT2 contains a rare UUG start codon (I. S. Lee, J. Lin, H. K. Hall, B. Bearson, and J. W. Foster, Mol. Microbiol. 17:155-167, 1995). This difference is responsible for the inability of LT2 to display a sustained log-phase acid tolerance response. We show that the altered rpoS allele (rpoS(LT2)) also affects the stationary-phase acid tolerance response in Salmonella. By transducing the rpoS(LT2) allele into virulent strain backgrounds and crossing wild-type rpoS allele into strain LT2, we demonstrate that the rpoS(LT2) allele contributes to the attenuation of strain LT2. We examined the effect of the rpoS allele on invasion and found that the rpoS status of the cell had no effect on the ability of the strains to invade intestinal epithelial cells in tissue culture. Enumeration of bacteria from tissues of infected mice indicated that the ...
Clonally derived bacterial populations exhibit significant genotypic and phenotypic diversity that contribute to fitness in rapidly changing environments. Here, we show that serial passage of Salmonella enterica serovar Typhimurium LT2 (StLT2) in broth, or within a mouse host, results in selection of an evolved population that inhibits the growth of ancestral cells by direct contact. Cells within each evolved population gain the ability to express and deploy a cryptic "orphan" toxin encoded within the rearrangement hotspot (rhs) locus. The Rhs orphan toxin is encoded by a gene fragment located downstream of the "main" rhs gene in the ancestral strain StLT2. The Rhs orphan coding sequence is linked to an immunity gene, which encodes an immunity protein that specifically blocks Rhs orphan toxin activity. Expression of the Rhs orphan immunity protein protects ancestral cells from the evolved lineages, indicating that orphan toxin activity is responsible for the observed growth inhibition. Because ...
Salmonella can survive for long periods under extreme desiccation conditions. This stress tolerance poses a risk for food safety, but relatively little is known about the molecular and cellular regulation of this adaptation mechanism. To determine the genetic components involved in Salmonellas cellular response to desiccation, we performed a global transcriptomic analysis comparing S. enterica serovar Typhimurium cells equilibrated to low water activity (aw 0.11) and cells equilibrated to high water activity (aw 1.0). The analysis revealed that 719 genes were differentially regulated between the two conditions, of which 290 genes were up-regulated at aw 0.11. Most of these genes were involved in metabolic pathways, transporter regulation, DNA replication/repair, transcription and translation, and, more importantly, virulence genes. Among these, we decided to focus on the role of sopD and sseD. Deletion mutants were created and their ability to survive desiccation and exposure to aw 0.11 was compared to
The comparison of the publicly available genomes of the virulent Salmonella serovar Typhimurium strains SL1344, 14028s, D23580 to that of the virulence attenuated isolate LT2 revealed the absence of a full sequence of bacteriophage ST64B in the latter. Four selected ST64B regions of unknown function (sb7-sb11, sb46, sb49-sb50, and sb54) were mapped by PCR in two strains collections; 1) 310 isolates of S. Typhimurium from human blood or stool samples and from food, animal and environmental reservoirs, and 2) 90 isolates belonging to other serovars. The region sb49-sb50 was found to be unique to S. Typhimurium and was strongly associated to strains isolated from blood samples (100% and 28.4% of the blood and non-blood isolates, respectively). The region was cloned into LT2 and knocked out in SL1344 and these strains were compared to wild type isogenic strains in in vitro assays used to predict virulence association. No difference in invasion of the Int407 human cell line was observed between the ...
a CIP, ciprofloxacin; CTZ, ceftriaxone; ND, not determined. CIP (MIC, ≥4 μg/ml), Salmonella isolates with ciprofloxacin MIC of ≥4 μg/ml; CTZ (MIC, ≥4 μg/ml), Salmonella isolates with ceftriaxone MIC of ≥4 μg/ml; CIP, CTZ (MIC, ≥4 μg/ml), Salmonella isolates with both ciprofloxacin and ceftriaxone MICs of ≥4 μg/ml. ...
BACKGROUND: Salmonella infections cause gastrointestinal and systemic diseases worldwide and are the leading causes of food-borne illnesses in North America (1-4). Salmonella serotype typhimurium (ST), in particular, is increasingly becoming a major public health concern because of its ability to acquire multiple resistant genes (5,6).OBJECTIVE: To describe demographic, temporal and geographical distributions, and reported risk factors of nonoutbreak cases of ST reported to a surveillance system in Ontario.METHODOLOGY: Descriptive analyses were performed on data on salmonellosiscases reported in Ontario between 1990 and 1998. Direct age- and sex-standardized rates were computed, and temporal trend analyses were performed using simple linear regression and a general additive model with alocally weighted regression (LOESS) smoother.RESULTS: The mean annual rates of infections with all Salmonella serotypes and with ST were 27 cases per 100,000 persons and 3.7 cases per 100,000 persons, ...
Salmonella typhimurium. Coloured transmission electron micrograph of Salmonella typhimurium bacteria dividing. The orange areas in the centre of the cells are the sites of the genetic material. This rod-shaped, Gram-negative species is a pathogen of many animals and is the commonest cause of food poisoning (Salmonellosis) in humans. It produces enterotoxins which act on the small intestine. Infection occurs when these bacteria contaminate food such as meat, milk and eggs. Symptoms of food poisoning include abdominal pain, nausea, vomiting and diarrhoea. The infection is usually controllable and is rarely fatal. Magnification x34,300 at 6x7cm size. - Stock Image B220/0830
DNA in intracellular Salmonella enterica serovar Typhimurium relaxes during growth in the acidified (pH 4-5) macrophage vacuole and DNA relaxation correlates…
HilA activates the expression of Salmonella enterica serovar Typhimurium invasion genes. To learn more about regulation of hilA, we isolated Tn5 mutants exhibiting reduced hilA and/or invasion gene expression. In addition to expected mutations, we identified Tn5 insertions in pstS, fadD, flhD, flhC, and fliA. Analysis of the pstS mutant indicates that hilA and invasion genes are repressed by the response regulator PhoB in the absence of the Pst high-affinity inorganic phosphate uptake system. This system is required for negative control of the PhoR-PhoB two-component regulatory system, suggesting that hilA expression may be repressed by PhoRPhoB under low extracellular inorganic phosphate conditions. FadD is required for uptake and degradation of long-chain fatty acids, and our analysis of the fadD mutant indicates that hilA is regulated by a FadDdependent, FadR-independent mechanism. Thus, fatty acid derivatives may act as intracellular signals to regulate hilA expression. flhDC and fliA encode
Involvement of ISCR3 and ISCR1 with the Salmonella genomic island 1 genetic element.SGI1 is a genetic element of approximately 43 kb (15). It has been associated mainly with MDR isolates of S. enterica serovar Typhimurium phage type DT104 that are resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline. This pathogen emerged in the last decade as a global animal and human health problem (15). Outbreaks of MDR S. enterica serovar Typhimurium DT104 have occurred in poultry, beef, and pigs and their food products, as well as in dairy products and salad ingredients. MDR salmonellae are very common in the United Kingdom and increasingly prevalent in many other countries (15).. Since its initial discovery in S. enterica serovar Typhimurium DT104, SGI1 has also been found in other S. enterica serovar Typhimurium phage types, i.e., DT120, DT12, DT1, and U302, and in other serovars such as Agona, Paratyphi B, Albany, Meleagridis, Newport, Emek, Cerro, Derby, Dusseldorf, ...
Spread of multidrug-resistant strains of Salmonella enterica serotype Typhimurium (S. typhimurium) is increasingly reported worldwide. The presence of a pattern of resistance to ampicillin, chloramphe
Herbicides are frequently released into both rural and urban environments. Commercial herbicide formulations induce adaptive changes in the way bacteria respond to antibiotics. Salmonella enterica sv. Typhimurium and Escherichia coli were exposed to common co-formulants of formulations, and S. enterica sv. Typhimurium was exposed to active ingredients dicamba, 2,4-D and glyphosate to determine what ingredients of the commercial formulations caused this effect. Co-formulants Tween80 and carboxymethyl cellulose induced changes in response, but the pattern of the responses differed from the active ingredients, and effect sizes were smaller. A commercial wetting agent did not affect antibiotic responses. Active ingredients induced changes in antibiotic responses similar to those caused by complete formulations. This occurred at or below recommended application concentrations. Targeted deletion of efflux pump genes largely neutralized the adaptive response in the cases of increased survival in antibiotics,
TY - JOUR. T1 - Discovery of Salmonella virulence factors translocated via outer membrane vesicles to murine macrophages. AU - Yoon, Hyunjin. AU - Ansong, Charles. AU - Adkins, Joshua N.. AU - Heffron, Fred. PY - 2011/6. Y1 - 2011/6. N2 - Salmonella enterica serovar Typhimurium, an intracellular pathogen and leading cause of food-borne illness, encodes a plethora of virulence effectors. Salmonella virulence factors are translocated into host cells and manipulate host cellular activities, providing a more hospitable environment for bacterial proliferation. In this study, we report a new set of virulence factors that is translocated into the host cytoplasm via bacterial outer membrane vesicles (OMV). PagK (or PagK1), PagJ, and STM2585A (or PagK2) are small proteins composed of ~70 amino acids and have high sequence homology to each other (,85% identity). Salmonella lacking all three homologues was attenuated for virulence in a mouse infection model, suggesting at least partial functional ...
Massis, LM et al. Anti-flagellin antibody responses elicited in mice orally immunized with attenuated Salmonella enterica serovar Typhimurium vaccine strains. Mem. Inst. Oswaldo Cruz, Sept 2008, vol.103, no.6, p.606-610. ISSN 0074- ...
Role of outer membrane lipopolysaccharides in the protection of Salmonella enterica serovar Typhimurium from desiccation damage ...
Runkel, S (2014) Endogenous production and detoxification of a potent cytotoxin, nitric oxide, in Salmonella enterica serovar Typhimurium and Escherichia coli. Doctoral thesis, University of East Anglia. ...
1KEW: The crystal structure of dTDP-D-glucose 4,6-dehydratase (RmlB) from Salmonella enterica serovar Typhimurium with thymidine diphosphate bound
Gamma Interferon-Independent Effects of Interleukin-12 on Immunity to Salmonella enterica Serovar Typhimurium Journal Articles Refereed ...
Nalidixic acid resistance among Salmonella Typhimurium clinical isolates has steadily increased, whereas the level of ciprofloxacin resistance remains low. The main objective of this study was to characterize the fluoroquinolone resistance mechanisms acquired in a S. Typhimurium mutant selected with ciprofloxacin from a susceptible isolate and to investigate its invasion ability ...
Forty-seven Salmonella Typhimurium (33 zoonotic, 14 clinical) strains were tested for antimicrobial resistance using the standard disk diffusion method. The presence of relevant resistance genes and class 1 integrons were investigated by using PCR. Pulsed-field gel electrophoresis (PFGE) and plasmid profiling were carried out to determine the genomic diversity of Salmonella Typhimurium. Approximately 57.4 of the S. Typhimurium strains were multidrug resistant (MDR) and showed high resistance rates to tetracycline (70.2), sulfonamides (57.4), streptomycin (53.1), ampicillin (29.7), nalidixic acid (27.6), kanamycin (23.4), chloramphenicol (21.2), and trimethoprim (19.1). Resistance towards cephalosporins was noted for cephalothin (27.6), cephradine (21.2), amoxicillin clavulanic acid (17.0), and cephalexin (17.0). Resistance genes, bla(TEM), strA, aadA, sul1, sul2, tetA, tetB, and tetC, were detected among the drug-resistant strains. Thirty-three strains (70.2) carried class 1 integrons, which ...
The global epidemic of multidrug-resistant Salmonella Typhimurium DT104 provides an important example, both in terms of the agent and its resistance, of a widely disseminated zoonotic pathogen. Here, with an unprecedented national collection of isolates collected contemporaneously from humans and animals and including a sample of internationally derived isolates, we have used whole-genome sequencing to dissect the phylogenetic associations of the bacterium and its antimicrobial resistance genes through the course of an epidemic. Contrary to current tenets supporting a single homogeneous epidemic, we demonstrate that the bacterium and its resistance genes were largely maintained within animal and human populations separately and that there was limited transmission, in either direction. We also show considerable variation in the resistance profiles, in contrast to the largely stable bacterial core genome, which emphasizes the critical importance of integrated genotypic data sets in understanding ...
The image shows the bacterial pathogen Salmonella typhimurium, the most common cause of food poisoning, dividing within a macrophage. Macrophages normally destroy bacteria, but Salmonella is able to takes over the cell and create a hospitable environment for its own replication. At 24-hours post-infection the bacteria (dark ovals, surrounded by white vacuolar space) can be seen growing within macrophages to very high numbers by transmission electron microscopy.. ...
Salmonella is an important food borne pathogen. Over 100,000 cases of human Salmonella infection are reported in the European Union each year, resulting in an economic burden estimated to be around 3 billion Euros per year (EFSA, 2012). In a European Food Safety Authority (EFSA) survey between 2006 and 2007 S. Typhimurium was the most common serovar of Salmonella isolated from pig carcasses (EFSA, 2008a). Pigs can be asymptomatic carriers of S. Typhimurium (Berends et al., 1996) and contaminated pork contributes significantly to the number of human infections. It has been estimated that the porcine Salmonella reservoir contributes between 10-20% of human salmonellosis cases per year (VLA, 2010). In addition to improvements in biosecurity and husbandry practices, immune-prophylaxis is an important method to reduce the prevalence of food borne pathogens such as Salmonella in reservoir species. An understanding of the molecular basis of bacterial colonisation and persistence in the reservoir host ...
Typhimurium is the main serotype of Salmonella enterica subsp. enterica implicated in food-borne diseases worldwide. This study aimed to detect the prevalence of ten markers combined in a macro-array based on multiplex real-time PCR. We targeted characteristic determinants located on pathogenicity islands (SPI-2 to -5, virulence plasmid pSLT and Salmonella genomic island 1 (SGI1)) as well as a specific 16S-23S rRNA intergenic spacer sequence of definitive type 104 (DT104). To investigate antimicrobial resistance, the study also targeted the presence of genes involved in sulfonamide (sul1) and beta-lactam (blaTEM) resistance. Finally, the intI1 determinant encoding integrase from class 1 integron was also investigated. A total of 538 unrelated S. Typhimurium strains isolated between 1999 and 2009 from various sources, including food animals, food products, human and environmental samples were studied. Based on the combined presence or absence of these markers, we distinguished 34 different genotypes,
BACKGROUND: Infections with Salmonella cause significant morbidity and mortality worldwide. Replication of Salmonella typhimurium inside its host cell is a model system for studying the pathogenesis of intracellular bacterial infections. Genome-scale modeling of bacterial metabolic networks provides a powerful tool to identify and analyze pathways required for successful intracellular replication during host-pathogen interaction.. RESULTS: We have developed and validated a genome-scale metabolic network of Salmonella typhimurium LT2 (iRR1083). This model accounts for 1,083 genes that encode proteins catalyzing 1,087 unique metabolic and transport reactions in the bacterium. We employed flux balance analysis and in silico gene essentiality analysis to investigate growth under a wide range of conditions that mimic in vitro and host cell environments. Gene expression profiling of S. typhimurium isolated from macrophage cell lines was used to constrain the model to predict metabolic pathways that ...
Pathogenic Salmonella strains have a set of virulence factors allowing them to generate systemic infections and damage in a variety of hosts. Among these factors, bacterial proteins secreted by specialized systems are used to penetrate the host’s intestinal mucosa, through the invasion and destruction of specialized epithelial M cells in the intestine. On the other hand, numerous studies have demonstrated that humans, as well as experimental animal hosts, respond to Salmonella infection by activating both innate and adaptive immune responses. Here, through live cell imaging of S. Typhimurium infection of zebrafish larvae, we showed that besides the intestinal colonization, a deformed cloacae region and a concomitant accumulation of S. Typhimurium cells was observed upon bacterial infection. The swelling led to a persistent inflammation of infected larvae, although the infection was non-lethal. The in vivo inflammation process was confirmed by the co-localization of GFP-tagged S. Typhimurium with
The GeneChip Porcine Genome Array was used to identify the transcriptional response upon Salmonella typhimurium infection in three porcine intestinal sections (jejumun, ileum and colon) along a time course of 1,2 and 6 days post infection. The objetives in this study were i) characterize transcriptional changes upon S. typhimurium infection in the intestinal mucosa; ii) identify differences among porcine intestinal sections in inmune resposes against S. typhimurium; iii) identify change that could be associated to salmonellosis pathogenesis and symtomatology; and finally, iv) identify transcriptional changes that could be induced by S. typhimurium in order to get bacterial survival and successful colonization. Sixteen male and female crossbreeds weaned piglets, approximately 4 weeks of age, were used in this study. Before infection, faecal samples from each animal were analyzed to confirm that piglets were free of Salmonella. Pigs were housed in an environmentally controlled isolation facility at 25ºC
Many flagellar proteins are exported by a flagellum-specific export pathway. In an initial attempt to characterize the apparatus responsible for the process, we designed a simple assay to screen for mutants with export defects. Temperature-sensitive flagellar mutants of Salmonella typhimurium were grown at the permissive temperature (30 degrees C), shifted to the restrictive temperature (42 degrees C), and inspected in a light microscope. With the exception of switch mutants, they were fully motile. Next, cells grown at the permissive temperature had their flagellar filaments removed by shearing before the cells were shifted to the restrictive temperature. Most mutants were able to regrow filaments. However, flhA, fliH, fliI, and fliN mutants showed no or greatly reduced regrowth, suggesting that the corresponding gene products are involved in the process of flagellum-specific export. We describe here the sequences of fliH, fliI, and the adjacent gene, fliJ; they encode proteins with deduced ...
SpiC is a virulence factor encoded within Salmonella pathogenicity island 2 (SPI-2). We have previously reported that infection of macrophages with Salmonella enterica serovar Typhimurium results in the SPI-2-dependent activation of the mitogen-activated protein kinase (MAPK) signalling pathways, leading to the expression of suppressor of cytokine signalling (SOCS)-3, which is involved in the inhibition of cytokine signalling. Here, we investigated the mechanism by which SpiC mediates the activation of signal transduction pathways in macrophages. Proteomic analysis showed that the level of FliC protein, a component of the flagellar filaments, was lower in the culture supernatant of a spiC mutant than in the supernatant from wild-type Salmonella. Furthermore, quantitative real-time RT-PCR showed that this mutant had a much lower level of fliC mRNA, indicating that SpiC regulates the transcription of FliC. We also found that the level of SOCS-3 in J774 macrophages was lower when they were infected with
Salmonella Typhimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S. Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM), a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding. Then, biotin-labelled S. Typhimurium-antibody was immobilized onto the IDAM surface. Samples were dropped on the surface of the IDAM and the S. Typhimurium cells in the samples were captured by the antibody on the IDAM. This resulted in impedance changes that were measured and displayed with the LabVIEW software. An equivalent circuit of the immunosensor demonstrated that the largest change in
Catalyzes the dehydrogenation of acyl-coenzymes A (acyl-CoAs) to 2-enoyl-CoAs, the first step of the beta-oxidation cycle of fatty acid degradation. Is required for S.typhimurium to utilize medium- and long-chain fatty acids as sole carbon sources for growth. Is needed for bacterial survival during carbone-source starvation.
Chronic infections are often attributed to bacterial biofilms. These biofilms are extremely tolerant to antimicrobial treatment due to the presence of dormant persister cells. Whilst a number of persister genes and pathways have been identified, it is likely that others remain. Investigating persistence of S. Typhimurium was therefore undertaken. A csp null mutant of Salmonella enterica sv. Typhimurium, lacking all six cold shock protein (CspA) paralogues was previously constructed (Hutchinson 2005). At 10°C, this strain is unable to divide, but remains viable for several weeks. However it remains capable of growth at 37°C and thus is conditionally dormant. Using this strain, the link between dormancy and persistence was investigated. Treatment of stationary phase planktonic cultures with fluoroquinolones revealed persister cells in SL1344. In contrast the csp null mutant was completely eliminated by treatment at 37°C; this could be prevented by cspC or cspE expression, implicating a role for ...
2. Oliveira SD, Santos LR, Schuch DM, Silva AB, Salle CT, Canal CW. Detection and identification of salmonellas from poultry-related samples by PCR. Vet Microbiol. 2002;87:25-35. 3. Gebreyes WA, Altier C. Molecular characterization of multidrug-resistant Salmonella enterica subsp. enterica serovar Typhimurium isolates from swine. J Clin Microbiol. 2002;40:2813-2822. 4. Heisig P, Kratz B, Halle E, Graser Y, Altwegg M, Rabsch W, Faber JP. Identification of DNA gyrase A mutations in ciprofloxacin-resistant isolates of Salmonella typhimurium from men and cattle in Germany. Microb Drug Resist. 1995;1:211-218. 5. Carlson SA, Bolton LF, Briggs CE, Hurd HS, Sharma VK, Fedorka-Cray PJ, Jones BD. Detection of multiresistant Salmonella typhimurium DT104 using multiplex and fluorogenic PCR. Mol Cell Probes. 1999;13:213-222. 6. Chen W, Martinez G, Mulchandani A. Molecular beacons: a real-time polymerase chain reaction assay for detecting Salmonella. Anal Biochem. 2000;280:166-172. 7. Doran JL, Collinson SK, ...
A DNA fragment of approximately 900 base pairs, adjacent to the fljB (H2) gene, which specifies the synthesis of phase-2 flagellin, can exist in either orientation with respect to fljB. The orientation of the inversion region controls expression of fljB. The hin gene occupies about two-thirds of the inversion region; it is required for the inversion of the fljB controlling region.
The effect of a gelified matrix on the heat inactivation of Escherichia coli K12 and Salmonella typhimurium was investigated. Compared to liquid systems, microbial populations grow as colonies due to the gelified character of the solid environment. In addition, the effect of colony density as well as the effect of the concentration of the gelling agent on the microbial inactivation kinetics were studied. More specifically, E. coli K12 MG1655 or S. typhimurium cells were grown in a gelified medium (Brain Heart Infusion or Tryptic Soy broth supplemented with 1.5% or 2.5% (w/v) xanthan gum) at 37°C until they reached the stationary phase. Especially for E. coli, different colony densities were obtained by starting growth at 37°C from different initial cell counts, i.e., a lower inoculum level results in bigger stationary phase colonies. Hereafter, these colonies were inactivated at 54°C. Cells inactivated as colonies in the gelified environment are protected from heat stress, leading to an ...
Interactions between the enteric pathogen Salmonella typhimurium and the luminal surface of the intestine provoke an acute inflammatory response, mediated in part by epithelial cell secretion of the chemokine IL-8 and other proinflammatory molecules. This study investigated the mechanism by which this pathogen induces IL-8 secretion in physiologically polarized model intestinal epithelia. IL-8 secretion induced by both the prototypical proinflammatory cytokine TNF-α and S. typhimurium was NF-κB dependent. However, NF-κB activation and IL-8 secretion induced by S. typhimurium, but not by TNF-α, was preceded by and required an increase in intracellular [Ca2+]. Additionally, agonists that increased intracellular [Ca2+] by receptor-dependent (carbachol) or independent (thapsigargin, ionomycin) means also induced IL-8 secretion. Furthermore, the ability of S. typhimurium mutants to induce IκB-α degradation, NF-κB translocation, and IL-8 transcription and secretion correlated precisely with ...
Dendritic cells (DC) efficiently phagocytose invading bacteria, but fail to kill intracellular pathogens such as Salmonella enterica serovar Typhimurium (S. Typhimurium). We analysed the intracellular fate of Salmonella in murine bone marrow-derived DC (BM-DC). The intracellular proliferation and subcellular localization were investigated for wild-type S. Typhimurium and mutants deficient in Salmonella pathogenicity island 2 (SPI2), a complex virulence factor that is essential for systemic infections in the murine model and intracellular survival and replication in macrophages. Using a segregative plasmid to monitor intracellular cell division, we observed that, in BM-DC, S. Typhimurium represents a static, non-dividing population. In BM-DC, S. Typhimurium resides in a membrane-bound compartment that has acquired late endosomal markers. However, these bacteria respond to intracellular stimuli, because induction of SPI2 genes was observed. S. Typhimurium within DC are also able to translocate a ...
Kylt|sup|®|/sup| Salmonella Typhimurium DNA Extraction and Real-Time PCR Detection Kit is intended for the preparation and detection of bacterial DNA from Salmonella Typhimurium. The detection kit contains all reagents and controls necessary for reliable and accurate detection.
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
We have isolated a hemA26 mutant of S. enterica serovar Typhimurium in a genetic screen of insertion mutants that were sensitive to hydrogen peroxide. We show that hemA26 mutant is partially defective at heme biosynthesis, diminishing the rates at which it can both scavenge hydrogen peroxide and respire. Both effects are likely to have contributed to its sensitivity in the initial screen. When bacteria are incubated on plates laden with hydrogen peroxide, they only form colonies if they can maintain viability until they can reduce hydrogen peroxide to subinhibitory levels. Both the diminished rate of scavenging and the accelerated rate of DNA damage would compromise their effectiveness at doing so.. While the reduced scavenging activity is an obvious consequence of diminished catalase activity, the connection between poor respiration and accelerated DNA damage is less obvious. The present study shows that exposure of a heme-deficient mutant with reduced respiration to hydrogen peroxide results ...
Like the findings from Africa (6, 8), our results indicate the widespread occurrence of complement-dependent, antibody-mediated bactericidal activity against S. Typhimurium in sera from healthy adults in the Boston area, as well as an age-dependent increase in this activity during maturation from child to adult. However, in contrast to the results from Africa, the bactericidal antibodies in our study appear to be directed against S. Typhimurium LPS rather than outer membrane proteins. Our data also indicate that the bactericidal antibodies discriminate between LPS from S. Typhimurium and E. coli, suggesting that the antibodies recognize a determinant in the outer polysaccharide of LPS (22, 23). The bactericidal activities of 2 of our samples appeared to be affected by acetylation of the abequose residue in the LPS outer polysaccharide, suggesting fine differences in antigen specificity within our collection. IgG purified from our samples was sufficient to recapitulate the bactericidal activity ...
Susceptibility to infection by the intracellular bacterial pathogen, Salmonella enterica serovar Typhimurium (S. typhimurium), is controlled by many genes of innate and adaptive immunity. One of the most critical genes is IFN-γ and mice deficient in IFN-γ synthesis are highly susceptible to Salmonella. Previously, we also demonstrated that mice deficient in MyD88, an adaptor that regulates TLR signaling, are susceptible to Salmonella infection. In the current study, we compared immune responses in mice deficient in IFN-γ or MyD88 with wild-type controls following infection with an attenuated strain of S. typhimurium (designated BRD509) or a recombinant derivative engineered to express murine IFN-γ (GIDIFN). Infection studies with BRD509 or GIDIFN revealed that the latter strain was significantly less virulent in immunodeficient mice than BRD509 and correlated with decreased bacterial loads in systemic organs. Enhanced responsiveness was due to GIDIFN strains ability to activate effector ...
1. Ghosh AC. An epidemiological study of the incidence of Salmonella in pigs. J Hyg Camb. 1972;70:151-160.. 2. Ishiguro N, Sato G, Takeuchi K, et al. A longitudinal study of Salmonella infection on a piggery: A study of the mode of contamination by biotyping of Salmonella typhimurium and by the antiobiogram. Jap J Vet Sci. 1979;41:261-272.. 4. Mousing J, Jensen PT, Halgaard C, et al. Nationwide Salmonella enterica surveillance and control in Danish slaughter swine herds. Prev Vet Med. 1997;29:247-261.. 5. Berends BR, Urlings HAP, Snidjers JMA, et al. Identification of risk factors in animal management and transport regarding Salmonella spp. in pigs. Int J Food Microbiol. 1996;30:37-53.. 6. Dahl J, Wingstrand A, Nielsen B, et al. Elimination of Salmonella typhimurium infection by the strategic movement of pigs. Vet Rec. 1997;140:679-681.. 7. Davies PR, Bovee FGM, Funk JA, et al. Isolation of Salmonella serotypes from feces of pigs raised in a multiple-site production system. JAVMA. ...
The enzyme propanediol oxidoreductase, which converts the lactaldehyde formed in the metabolism of fucose and rhamnose into propane-1,2-diol under anaerobic conditions, was investigated in Escherichia coli, Klebsiella pneumoniae and Salmonella typhimurium. Structural analysis indicated that the enzymes of E. coli and K. pneumoniae have the same Mr and pI, whereas that of Salm. typhimurium also has the same Mr but a slightly different pI. One-dimensional peptide mapping showed identity between the E. coli and K. pneumoniae enzymes when digested with α-chymotrypsin, Staphylococcus aureus V8 proteinase or subtilisin. In the case of Salm. typhimurium, this held only for the subtilisin-digested enzymes, indicating that the hydrophobic regions were preserved to a considerable extent. Anaerobically, the three species induced an active propanediol oxidoreductase when grown on fucose or rhamnose. An inactive propanediol oxidoreductase was induced in Salm. typhimurium by either fucose or rhamnose under ...
Salmonella typhimurium OrgA protein: a Salmonella typhimurium oxygen-regulated invasion protein is required for bacterial internalization; amino acid sequence given in first source; GenBank L33855
TY - JOUR. T1 - Metabolic activation of m-phenylenediamine to products mutagenic in Salmonella typhimurium by medium isolated from tobacco suspension cell cultures. AU - Gichner, Tomáš. AU - Stavreva, Diana A.. AU - Čeřovská, Noemi. AU - Wagner, Elizabeth D.. AU - Plewa, Michael J.. PY - 1995/9. Y1 - 1995/9. N2 - Both tobacco cells in suspension and the medium recovered from the suspension cultures (TX1MX) activated the aromatic amine m-phenylenediamine (m-PDA) into a product that was mutagenic in Salmonella typhimurium TA98 and YG1024. Medium recovered from stationary-phase tobacco cell cultures exhibited the highest level of m-PDA activation. No cytochrome P-450 was detected in the activating medium. A high molecular weight matrix having the highest m-PDA activating capacity and associated with a substantial fraction of the total peroxidase activity was isolated by Centricon-100 ultrafiltration of TX1MX. The data suggest that the peroxidases present in the recovered cell culture medium or ...
This report published in Communicable Diseases Intelligence Volume 27, No 2, June 2003 describes an outbreak of Salmonella Typhimurium phage type 135a in a child care centre.
TLRs are key sensors for conserved bacterial molecules and play a critical role in host defense against invading pathogens. Although the roles of TLRs in defense against pathogen infection and in maintaining gut immune homeostasis have been studied, the precise functions of different TLRs in response to pathogen infection in the gut remain elusive. The present study investigated the role of TLR signaling in defense against the Gram-negative bacterial pathogen Salmonella typhimurium. The results indicated that TLR9-deficient mice were more susceptible to S. typhimurium infection compared with wild-type and TLR2- or TLR4-deficient mice, as indicated by more severe intestinal damage and the highest bacterial load. TLR9 deficiency in intestinal epithelial cells (IECs) augmented the activation of NF-κB and NLRP3 inflammasomes significantly, resulting in increased secretion of IL-1β. IL-1β increased the expression of NKG2D on intestinal intraepithelial lymphocytes and NKG2D ligands on IECs, ...
ALMEIDA, FERNANDA... Draft Genome Sequences of 40 Salmonella enterica Serovar Typhimurium Strains Isolated from Humans and Food in Brazil. MICROBIOLOGY RESOURCE ANNOUNCEMENTS 4 n.5 p. SEP-OCT 2016. Journal article.
Salmonella typhimurium Antibodies available through Novus Biologicals. Browse our Salmonella typhimurium Antibodies all backed by our Guarantee+.
Salmonellosis is a public health problem primarily caused by consumption of pork products contaminated with S. Typhimurium [2]. On the contrary, S. Choleraesuis, a host-adapted serovar in pigs, causes a typhoid-like disease in piglets, which is characterized by reduced growth and, in the most severe cases, a high mortality rate, and hence mainly representing an economic problem [1, 18]. S. Choleraesuis is not considered to be a major agent of zoonotic infections, although some cases of human infection have been recorded, especially in Asia [8].. Vaccination of pigs could represent a valid control system in countries with a high prevalence of salmonellosis in animals. Attenuated vaccines are more effective than inactivated ones in protecting against enteric diseases, due to their ability to induce cell-mediated and mucosal immunity [19]. To address this issue, in previous study we assessed the safety and efficacy of S. Typhimurium ΔznuABC strain in different models of infection [11-16]. In the ...
Bacterial strain, cell line and culture conditions The strain of S. typhimurium (fim+ve) was obtained from Dr. Philip T. Loverde (State University of New York, Buffalo). Bacteria were grown on Luria agar for 48h at 37 oC. INT-407 (human embryo small intestinal epithelial cell line) was obtained from National Centre for Cell Science (Pune), grown in RPMI medium containing fetal bovine serum (10%), L-glutamine (5mM), streptomycin (100µg/ml) and penicillin (100µg/ml) at 37 oC in a CO2 incubator .. Purification of fimbrial adhesin. The method of Moch et al. [12] (with slight modifications) was used to isolate the fimbrial adhesin of S. typhimurium [12]. Briefly, the bacteria cultured on Luria agar were collected, washed and suspended in 10mM Tris/HCl (pH 7.8) buffer. This was followed by detachment of the fimbriae from the bacteria by omnimixing (10min) at 8-10 oC and centrifugation at 12000 x g for 30min.The supernatant containing fimbriae was further centrifuged (227,000 x g, 2.5h) and the ...
in Poultry Science (2011), 90(1), 59-67. In this study, Salmonella enterica serovar Typhimurium challenge models were tested to identify the best conditions under which to perform the experimental infection of 3-wk-old broilers. Such a model ... [more ▼]. In this study, Salmonella enterica serovar Typhimurium challenge models were tested to identify the best conditions under which to perform the experimental infection of 3-wk-old broilers. Such a model would be useful to study the efficiency of therapeutic treatments that could take place at the end of the grow-out period. Salmonella-free chicks were obtained from a breeder flock vaccinated with Salmonella. Intestinal maternal immunity was monitored by ELISA analyses at 2, 9, and 16 d of age. Data indicated that protection of maternal origin was not maintained over time and was drastically reduced at 9 d of age (P , 0.01). At 21 d of age, chickens were orally inoculated with Salmonella Typhimurium. The effects of the oral challenge dose (0, 3 ...
High-level fluoroquinolone (FQ) resistance is still infrequent in salmonellae, compared with other pathogenic enterobacteria. Data provided in this work support the hypothesis that the mechanisms that confer high-level FQ resistance on salmonellae have a prohibitive fitness cost and may thus limit the emergence of highly resistant clones. In vitro mutants that were highly resistant to ciprofloxacin (MIC = 8 and 16 μg ml−1) showed generation times 1.4- and 2-fold longer than their parent strains and were unable to colonize the gut of chickens. Electron microscopy showed an altered morphology for one of these mutants grown to stationary phase. Mutants selected in vivo and exhibiting intermediate resistance to ciprofloxacin (MIC = 2 μg ml−1) also showed growth defects on solid media but had normal generation times in liquid culture and colonized the gut of chickens. After in vitro or in vivo passage in the absence of antibiotic selective pressure, partial reversals of the fitness cost were observed,
... - - 1. Salmonella Gallinarium Disease caused by one of the two poultry-adapted strains of Salmonella bacteria, Salmonella Gallinarium. This can cause mortality in birds of any age. Infections still occur worldwide in non-commercial poultry but are rare in most commercial systems now. Salmonella Gallinarium infects the chicken�s liver, kidneys, spleen and the anterior small intestine. Morbidity is 10-100%; mortality is increased in stressed or immunocompromised flocks and may be up to 100%. The route of infection is oral or via the navel/yolk. The bacterium is fairly resistant to normal climate, surviving months, but is susceptible to normal disinfectants. At Kiepersol Poultry Farm (Pty) Ltd. we do preventative vaccination for the SG virus. Salmonella Gallinarium is specific for poultry and is 100% safe for humans since the virus can not be passed over to the egg. 2. Salmonella Enteritidis Salmonella Enteritidis and Salmonella Typhimurium are presented separately from
Typhoid fever and salmonellosis, which are caused by Salmonella Typhi and Typhimurium respectively, are responsible for significant morbidity and mortality in both developed and developing countries. We model typhoid fever using mice infected with Salmonella Typhimurium, which results in a systemic disease, whereby the outcome of infection is variable in different inbred strains of mice. This model recapitulates several clinical aspects of the human disease and allows the study of the host response to Salmonella Typhimurium infection in vivo. Previous work in our laboratory has identified three loci (Ity, Ity2 and Ity3) in the wild-derived MOLF/Ei mice influencing survival after infection with Salmonella Typhimurium. Fine mapping of the Ity3 locus indicated that two sub-loci contribute collectively to the susceptibility of B6.MOLF-Ity/Ity3 congenic mice to Salmonella infection. In the current paper, we provided further evidence supporting a role for Ncf2 (neutrophil cytosolic factor 2 a subunit of NADPH
The role of RNI during experimental salmonellosis in murine hosts has recently been demonstrated (21, 22). To elucidate the role of RNI in the cellular microbiology of Salmonella, we first investigated how a cultured macrophage-like cell line reacts to infection with S. typhimurium. RAW267.4 macrophages were infected with S. typhimurium wild-type and the NO response as measured by nitrite accumulation was studied. An increase in the MOI resulted in a gradual increase of the nitrite production by the RAW267.4 cells at early time after infection (Fig. 1 A). 8 h after infection, no significant difference in nitrite production was observed after infection at various MOI in the range of 10 to 150. In contrast, macrophages infected with heat-killed bacteria did not exhibit significant nitrite accumulation after 8 h (Fig. 1 B). After 24 h, accumulation of nitrite was detectable but lower than that observed with live Salmonella. This residual nitrite accumulation may be due to LPS, which is a prime ...
Background. Infection due to Salmonella species causes an estimated 1.4 million illnesses and 400 deaths annually in the United States. Orange juice is a known vehicle of salmonellosis, for which regulatory controls have recently been implemented. We investigated a nationwide outbreak of Salmonella infection to determine the magnitude of the outbreak and to identify risk factors for infection.. Methods. We identified cases through national laboratory-based surveillance. In a case-control study, we defined a case as infection with Salmonella serotype Typhimurium that demonstrated the outbreak pulsed-field gel electrophoresis pattern in a person with illness onset from 1 May through 31 July 2005; control subjects were identified through random digit dialing.. Results. We identified 152 cases in 23 states. Detailed information was available for 95 cases. The median age of patients was 23 years; 46 (48%) of the 95 patients were female. For 38 patients and 53 age-group matched control subjects in 5 ...
An outbreak of primarily pediatric Salmonella Typhimurium infections in the United States has been traced to aquatic African dwarf frogs kept as pets.
BioAssay record AID 200885 submitted by ChEMBL: Compound was tested for the mutagenicity activity in the Salmonella Typhimurium reverse mutation assay; +++-indicates the levels of mutagenicity as the number of revertant colonies obtained increases 10 times.
Salmonella typhimurium has three distinct Mg2+ transport systems, the constitutive high-capacity CorA transporter and two P-type ATPases, MgtA and MgtB, whose transcription is repressed by normal concentrations of Mg2+ in the growth medium. The latter Mg2+-transporting ATPase is part of a two-gene operon, mgtCB, with mgtC encoding a 23 kDa protein of unknown function. Transcriptional regulation using fusions of the promoter regions of mgtA and mgtCB to luxAB showed a biphasic time and Mg2+ concentration dependence. Between 1 and 6 h after transfer to nitrogen minimal medium containing defined concentrations of Mg2+, transcription increased about 200-fold for mgtCB and up to 400-fold for mgtA, each with a half-maximal dependence on Mg2+ of 0.5 mM. Continued incubation revealed a second phase of increased transcription, up to 2000-fold for mgtCB and up to 10000-fold for mgtA. This secondary increase occurred between 6 and 9 h after transfer to defined medium for mgtCB but between 12 and 24 h for mgtA and
Microbial pathogens like Salmonella utilize numerous strategies to rapidly sense and respond to a myriad of environmental stresses. Oxidative, nitrosative, and nutritional stress imposed by the innate immune response are prominent among the antimicrobial pressures encountered by Salmonella during their association with mammalian hosts. The stringent response to nutritional stress, which is under the control of the RNA polymerase-binding protein DksA and the nucleotide alarmone guanosine penta/tetraphosphate [(p)ppGpp], is essential for Gram-negative pathogens to respond to nutrient limiting conditions. This stress program activates transcription of amino acid biosynthetic genes while repressing the expression of translational machinery. Investigations presented in this thesis indicate that, in addition to controlling the stringent response to nutritional stress, DksA and (p)ppGpp promote the transcription and translation of genes encoding the Salmonella Pathogenicity Island 2 (SPI2) virulence ...
Resistance to 16 antimicrobial agents was monitored in 109,125 Salmonella cultures isolated from animals, their environment and feedstuffs between 1988 and 1999. The sensitivity of the 6512 isolates of Salmonella enterica enterica serotype Dublin to all the antimicrobial agents tested varied from 98.2 per cent in 1997 to 99.7 per cent in 1990 and 1996. In contrast, among 28,053 isolates of Salmonella enterica enterica serotype Typhimurium, there was a marked decrease in their sensitivity to all the antimicrobial agents tested, from 57.4 per cent in 1992 to 7.6 per cent in 1995, owing to the widespread occurrence in farm animals of S Typhimurium isolates of the definitive type DT104, resistant to ampicillin, sulphonamides, streptomycin, chloramphenicol and tetracyclines, although the percentage of sensitive isolates increased to 18.4 per cent in 1999, when the incidence of DT104 had decreased. Some isolates of DT104 also showed an increase in resistance to potentiated sulphonamides (2.4 per cent ...
Bacterial infections of mammalian hosts are arguably among the most complex biological processes, often comprising a multitude of interacting organisms from different kingdoms. How do bacterial pathogens promote infection and what defense mechanisms do they have to overcome in order to colonize? What molecular mechanisms manifest the protective role of the microbiota against pathogenic attack? And what is the role of noncoding RNAs in host-microbiota-pathogen crosstalk? These and related questions are addressed in our group. Using cutting-edge RNA-sequencing-based techniques, our research centers on the identification and functional characterization of noncoding RNA molecules in the enteric pathogen Salmonella Typhimurium, the important intestinal microbiota member Bacteroides thetaiotaomicron, and the human host, to identify those RNAs that may serve as biomarkers for diagnosis or as therapeutic targets in the future. In addition to contributing to the field by the development of novel ...
It has been reported previously that the expression of the regulon genes of many two-component systems (Soncini et al., 1995; Wosten et al., 2000; Oshima et al., 2002; Takaya et al., 2005) as well as those of the RcsCDB system (Castanie-Cornet et al., 2007) are modulated by high levels of the regulator, even in the absence of the sensor. In this report, for the first time, it is demonstrated that rcsB overexpression significantly inhibits rcsD transcription, but has a weak effect on rcsB expression (Fig. 1), suggesting that the rcsB gene may be transcribed in an rcsD-independent manner. The identification of the PrcsB promoter driving rcsB expression (Figs 4 and 5) as well as a small 0.67-kb transcript corresponding in size to the rcsB mRNA strongly support our notion (Fig. 3). However, Detweiler et al. (2003) suggested that a region of ≈500 nucleotides upstream of rcsD was required for the expression of both genes as an operon. Our findings have shown that differential rcsD and rcsB ...
PubMed Central Canada (PMC Canada) provides free access to a stable and permanent online digital archive of full-text, peer-reviewed health and life sciences research publications. It builds on PubMed Central (PMC), the U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature and is a member of the broader PMC International (PMCI) network of e-repositories.
A mathematical model for nonrandom generalized transduction is proposed and analyzed. The model takes into account the finite number of transducing particle classes for any given marker. The equations for estimation of the distance between markers from cotransduction frequency data are derived and standard errors of the estimates are given. The obtained relationships depend significantly on the number of classes of transducing fragments. The model was applied to estimate the number of transducing fragment classes for a given marker in transduction with phage P22 of Salmonella typhimurium. It was found that the literature data on frequencies of cotransduction in crosses with mutual substitution of selective and nonselective markers can be rationalized most accurately by assuming that the mean number of classes is equal to 2. An improved method for analysis of cotransduction data is proposed on the basis of our model and the results of calculation. The method relies on solving a set of algebraic ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
Joe & The Juice, a Danish-born juice bar and coffee shop once found mostly in European airports, is opening location this year from San Francisco to Chicago.. NIPH is monitoring the outbreak to determine if it will be limited to the existing cases or if it will grow larger. The same DNA "fingerprint" for Salmonella typhimurium bacteria has been confirmed in all seven victims, suggesting a common source.. While the same airport restaurant connects the sickened individuals, their residences are disconnected, scattered throughout the country.. The NIPH investigation began in August when the victims began experiencing diarrhea, fever and abdominal pain. The typhimurium stereotype of Salmonella bacteria causes more severe symptoms than other Salmonella varieties.. Norway sees only about 1,200 to 2,000 Salmonella illnesses annually. About 70 percent of those are from infections contracted outside of the country. Most of the other infections are from imported foods.. Food produced in Norway and ...
Essential to bacterial pathogenesis, Salmonella enterica serovar Typhimurium (S. Typhimurium) has evolved the capacity to quickly sense and adapt to specific intracellular environment within distinct host cells. Here we examined S. Typhimurium proteomic remodeling within macrophages, allowing direct comparison with our previous studies in epithelial cells. In addition to many shared features, our data revealed proteomic signatures highly specific to one type of host cells. Notably, intracellular S. Typhimurium differentially regulates the two type III secretion systems (T3SSs) far more quickly in macrophages than in epithelial cells; bacterial flagellar and chemotaxis systems degenerate more quickly in macrophages than in HeLa cells as well. Importantly, our comparative analysis uncovered high levels of induction of bacterial histidine biosynthesis in macrophages but not in epithelial cells. Targeted metabolomic measurements revealed markedly lower histidine levels within macrophages. ...
A free platform for explaining your research in plain language, and managing how you communicate around it - so you can understand how best to increase its impact.
SseL, a Salmonella deubiquitinase required for macrophage killing and virulence: Expression of the Salmonella enterica serovar Typhimurium pathogenicity island
A phase I feasibility trial of a live, genetically modified Salmonella typhimurium bacillus (VNP20009) for the treatment of cancer by intra-tumoral injection ...
In vitro: Study 1. A study was conducted to determine the in vitr ogenetic toxicity of the test substance according to a method similar to OECD Guideline 471, in compliance with GLP. Salmonella typhimurium strains TA97, TA98, TA100 and TA1535 were treated with the test substance using the Ames plate incorporation method. Tests were carried out in triplicate, both with and without the addition of metabolic activation (S9-mix). The concentration range of the test substance was 0.8 to 2,500 µg/plate. Cytotoxicity was observed at ≥100 µg/plate. No significant increase in the frequency of revertant colonies was recorded for any of the bacterial strains at any of the test substance concentrations tested, either with or without metabolic activation.Under the study conditions, the test substance was not mutagenic in Salmonella typhimurium strain TA97, TA98, TA100 or TA1535, with or without metabolic activation (Muller, 1995). Study 2.A study was conducted to determine the in vitro genetic toxicity ...
cansSAR 3D Structure of 1F52_F | CRYSTAL STRUCTURE OF GLUTAMINE SYNTHETASE FROM SALMONELLA TYPHIMURIUM CO-CRYSTALLIZED WITH ADP | 1F52
The Salmonella family includes over 2,300 serotypes of bacteria which are one-celled organisms too small to be seen without a microscope. Two types, Salmonella Enteritidis and Salmonella Typhimurium are the most common in the United States and account for half of all human infections. Strains that cause no symptoms in animals can make people sick, and vice versa. If present in food, it does not usually affect the taste, smell, or appearance of the food. The bacteria live in the intestinal tracts of infected animals and humans ...
MOESM3 of Transcriptional analysis of porcine intestinal mucosa infected with Salmonella Typhimurium revealed a massive inflammatory response and disruption of bile acid absorption in ileum
Monophasic Salmonella Typhimurium - Efficacy of vaccine administration Since mid- 1990´s a number of reports have been published on the isolation of
Salmonella typhimurium encounters a variety of acid conditions during both its natural and pathogenic existence. The ability of this organism to respond transcriptionally to low pH is an area of active interest but little knowledge. As part of an ongoing investigation of low-pH adaptation, 18 pH-con …
Wells, Hannah (2015) Further characterisation of the envelope stress responses of Salmonella Typhimurium. Doctoral thesis, University of East Anglia. ...
Escherichia coli K-12 and Salmonella enterica serovar Typhimurium LT2 became standard organisms for genetic analysis during the Truman administration. Half a century later, genetic analysis with these strains had become an art form, interpreted through 23 articles in the ambitious two-volume masterpiece edited by the late Fred Neidhardt and colleagues. These legacy articles now are available through EcoSal Plus, so as to inform and inspire contemporary genetic analyses in these standard organisms and their relatives.
>Salmonella Typhimurium DT8 was a very rare cause of human illness in Ireland between 2000 and 2008, with only four human isolates from three patients being identified. Over a 19-month period between August 2009 and February 2011, 34 confirmed cases and one probable case of Salmonella Typhimurium DT8 were detected, all of which had an MLVA pattern 2-10-NA-12-212 or a closely related pattern. The epidemiological investigations strongly supported a link between illness and exposure to duck eggs. Moreover, S. Typhimurium with an MLVA pattern indistinguishable (or closely related) to the isolates from human cases, was identified in 22 commercial and backyard duck flocks, twelve of which were linked with known human cases. A range of control measures were taken at farm level, and advice was provided to consumers on the hygienic handling and cooking of duck eggs. Although no definitive link was established with a concurrent duck egg-related outbreak of S. Typhimurium DT8 in the United Kingdom, it seems
The objective of this study was to evaluate the potential of the test item to induce reverse mutations in Salmonella typhimurium. The study was performed according to the international guidelines (OECD No. 471 and Commission Directive No. B.13/14) and in compliance with the principles of Good Laboratory Practice. Methods A preliminary toxicity test was performed to define the dose levels of the test item, dissolved in dimethylsulfoxide (DMSO), to be used for the mutagenicity experiments. The test item was then tested in two independent experiments, both with and without a metabolic activation system, the S9 mix, prepared from a liver post-mitochondrial fraction (S9 fraction) of rats induced with Aroclor 1254. Treatments were performed according to the direct plate incorporation method except for the second experiment with S9 mix, which was performed according to the pre-incubation method (60 minutes, 37°C). Five strains of bacteria Salmonella typhimurium were used: TA 1535, TA 1537, TA 98, TA ...
TY - JOUR. T1 - The Salmonella effector SpvD is a cysteine hydrolase with a serovar-specific polymorphism influencing catalytic activity, suppression of immune responses, and bacterial virulence. AU - Grabe, Grzegorz J.. AU - Zhang, Yue. AU - Przydacz, Michal. AU - Rolhion, Nathalie. AU - Yang, Yi. AU - Pruneda, Jonathan. AU - Komander, David. AU - Holden, David W.. AU - Hare, Stephen A.. PY - 2016/12/9. Y1 - 2016/12/9. N2 - Many bacterial pathogens secrete virulence (effector) proteins that interfere with immune signaling in their host. SpvD is a Salmonella enterica effector protein that we previously demonstrated to negatively regulate the NF-κB signaling pathway and promote virulence of S. enterica serovar Typhimurium in mice. To shed light on the mechanistic basis for these observations, we determined the crystal structure of SpvD and show that it adopts a papain-like fold with a characteristic cysteine-histidine-aspartate catalytic triad comprising Cys-73, His-162, and Asp-182. SpvD ...
Background The serine/threonine protein kinase C (PKC) theta has been firmly implicated in T cell-mediated immunity. Because its role in macrophages has remained undefined, we employed PKCtheta-defici...
Typhoid fever, also acknowledged as Salmonella Typhi or just Typhoid, is a worldwide common illness that transmits by ingestion of water or food contaminated with feces of an infected person. Then the bacteria Salmonella Typhi perforate through the wall of the intestinal and phagocytes by macrophages and alerts its structure to enforce their existence within Read more ...
Klein JA, Dave BM, Raphenya AR, McArthur AG, Knodler LA.. Mol Microbiol. 2017 Mar;103(6):973-991.. Type III Secretion Systems (T3SSs) are structurally conserved nanomachines that span the inner and outer bacterial membranes, and via a protruding needle complex contact host cell membranes and deliver type III effector proteins. T3SS are phylogenetically divided into several families based on structural basal body components. Here we have studied the evolutionary and functional conservation of four T3SS proteins from the Inv/Mxi-Spa family: a cytosolic chaperone, two hydrophobic translocators that form a plasma membrane-integral pore, and the hydrophilic tip complex translocator that connects the T3SS needle to the translocon pore. Salmonella enterica serovar Typhimurium (S. Typhimurium), a common cause of food-borne gastroenteritis, possesses two T3SSs, one belonging to the Inv/Mxi-Spa family. We used invasion-deficient S. Typhimurium mutants as surrogates for expression of translocator ...
Genetic mutation in vitro; Prediction model based estimation and data from read across chemical have been reviewed to determine the mutagenic nature of Disodium [μ-[[7,7-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-)(6798-03-4). The studies are as mentioned below Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, gene mutation was predicted for Disodium [μ-[[7,7-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-)(6798-03-4). The study assumed the use of Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 with and without S9 metabolic activation system. Disodium [μ-[[7,7-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-)was predicted to not induce gene mutation in Salmonella typhimurium strains TA 1535, ...
The Ames test is a widely employed method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism. More formally, it is a biological assay to assess the mutagenic potential of chemical compounds. A positive test indicates that the chemical is mutagenic and therefore may act as a carcinogen, because cancer is often linked to mutation. The test serves as a quick and convenient assay to estimate the carcinogenic potential of a compound because standard carcinogen assays on mice and rats are time-consuming (taking two to three years to complete) and expensive. However, false-positives and false-negatives are known. The procedure was described in a series of papers in the early 1970s by Bruce Ames and his group at the University of California, Berkeley. The Ames test uses several strains of the bacterium Salmonella typhimurium that carry mutations in genes involved in histidine synthesis. These strains are auxotrophic mutants, i.e. they require ...
Salmonella Typhimurium infection commonly results in symptoms such as abdominal pain, diarrhoea, fever, nausea and vomiting. The organism is transmitted via ingestion, usually of food contaminated by the faeces of an infected person or animal. The incubation period of Salmonella can range between 6 and 72 hours but is more commonly between 12 and 36 hours.1 There have also been instances of longer incubation periods of up to 16 days ...