Epidemiology of a Salmonella enterica subsp. Enterica serovar Typhimurium strain associated with a songbird outbreak.

USGS Publications Warehouse

Blehert, David S.; Hernandez, Sonia M.; Keel, Kevin; Sanchez, Susan; Trees, Eija; ,

2012-01-01

Salmonella enterica subsp. enterica serovar Typhimurium is responsible for the majority of salmonellosis cases worldwide. This Salmonella serovar is also responsible for die-offs in songbird populations. In 2009, there was an S. Typhimurium epizootic reported in pine siskins in the eastern United States. At the time, there was also a human outbreak with this serovar that was associated with contaminated peanuts. As peanuts are also used in wild-bird food, it was hypothesized that the pine siskin epizootic was related to this human outbreak. A comparison of songbird and human S. Typhimurium pulsed-field gel electrophoresis (PFGE) patterns revealed that the epizootic was attributed not to the peanut-associated strain but, rather, to a songbird strain first characterized from an American goldfinch in 1998. This same S. Typhimurium strain (PFGE type A3) was also identified in the PulseNet USA database, accounting for 137 of 77,941 total S. Typhimurium PFGE entries. A second molecular typing method, multiple-locus variable-number tandem-repeat analysis (MLVA), confirmed that the same strain was responsible for the pine siskin epizootic in the eastern United States but was distinct from a genetically related strain isolated from pine siskins in Minnesota. The pine siskin A3 strain was first encountered in May 2008 in an American goldfinch and later in a northern cardinal at the start of the pine siskin epizootic. MLVA also confirmed the clonal nature of S. Typhimurium in songbirds and established that the pine siskin epizootic strain was unique to the finch family. For 2009, the distribution of PFGE type A3 in passerines and humans mirrored the highest population density of pine siskins for the East Coast.

Type I interferon induces necroptosis in macrophages during infection with Salmonella enterica serovar Typhimurium

PubMed Central

Robinson, Nirmal; McComb, Scott; Mulligan, Rebecca; Dudani, Renu; Krishnan, Lakshmi; Sad, Subash

2014-01-01

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a virulent pathogen that induces rapid host death. Here we observed that host survival after infection with S. Typhimurium was enhanced in the absence of type I interferon signaling, with improved survival of mice deficient in the receptor for type I interferons (Ifnar1−/− mice) that was attributed to macrophages. Although there was no impairment in cytokine expression or inflammasome activation in Ifnar1−/− macrophages, they were highly resistant to S. Typhimurium–induced cell death. Specific inhibition of the kinase RIP1or knockdown of the gene encoding the kinase RIP3 prevented the death of wild-type macrophages, which indicated that necroptosis was a mechanism of cell death. Finally, RIP3-deficient macrophages, which cannot undergo necroptosis, had similarly less death and enhanced control of S. Typhimurium in vivo. Thus, we propose that S. Typhimurium induces the production of type I interferon, which drives necroptosis of macrophages and allows them to evade the immune response. PMID:22922364

Genome and transcriptome adaptation accompanying emergence of the definitive type 2 host-restricted Salmonella enterica serovar Typhimurium pathovar.

PubMed

Kingsley, Robert A; Kay, Sally; Connor, Thomas; Barquist, Lars; Sait, Leanne; Holt, Kathryn E; Sivaraman, Karthi; Wileman, Thomas; Goulding, David; Clare, Simon; Hale, Christine; Seshasayee, Aswin; Harris, Simon; Thomson, Nicholas R; Gardner, Paul; Rabsch, Wolfgang; Wigley, Paul; Humphrey, Tom; Parkhill, Julian; Dougan, Gordon

2013-08-27

Salmonella enterica serovar Typhimurium definitive type 2 (DT2) is host restricted to Columba livia (rock or feral pigeon) but is also closely related to S. Typhimurium isolates that circulate in livestock and cause a zoonosis characterized by gastroenteritis in humans. DT2 isolates formed a distinct phylogenetic cluster within S. Typhimurium based on whole-genome-sequence polymorphisms. Comparative genome analysis of DT2 94-213 and S. Typhimurium SL1344, DT104, and D23580 identified few differences in gene content with the exception of variations within prophages. However, DT2 94-213 harbored 22 pseudogenes that were intact in other closely related S. Typhimurium strains. We report a novel in silico approach to identify single amino acid substitutions in proteins that have a high probability of a functional impact. One polymorphism identified using this method, a single-residue deletion in the Tar protein, abrogated chemotaxis to aspartate in vitro. DT2 94-213 also exhibited an altered transcriptional profile in response to culture at 42°C compared to that of SL1344. Such differentially regulated genes included a number involved in flagellum biosynthesis and motility. IMPORTANCE Whereas Salmonella enterica serovar Typhimurium can infect a wide range of animal species, some variants within this serovar exhibit a more limited host range and altered disease potential. Phylogenetic analysis based on whole-genome sequences can identify lineages associated with specific virulence traits, including host adaptation. This study represents one of the first to link pathogen-specific genetic signatures, including coding capacity, genome degradation, and transcriptional responses to host adaptation within a Salmonella serovar. We performed comparative genome analysis of reference and pigeon-adapted definitive type 2 (DT2) S. Typhimurium isolates alongside phenotypic and transcriptome analyses, to identify genetic signatures linked to host adaptation within the DT2 lineage.

ssrA (tmRNA) Plays a Role in Salmonella enterica Serovar Typhimurium Pathogenesis

PubMed Central

Julio, Steven M.; Heithoff, Douglas M.; Mahan, Michael J.

2000-01-01

Escherichia coli ssrA encodes a small stable RNA molecule, tmRNA, that has many diverse functions, including tagging abnormal proteins for degradation, supporting phage growth, and modulating the activity of DNA binding proteins. Here we show that ssrA plays a role in Salmonella enterica serovar Typhimurium pathogenesis and in the expression of several genes known to be induced during infection. Moreover, the phage-like attachment site, attL, encoded within ssrA, serves as the site of integration of a region of Salmonella-specific sequence; adjacent to the 5′ end of ssrA is another region of Salmonella-specific sequence with extensive homology to predicted proteins encoded within the unlinked Salmonella pathogenicity island SPI4. S. enterica serovar Typhimurium ssrA mutants fail to support the growth of phage P22 and are delayed in their ability to form viable phage particles following induction of a phage P22 lysogen. These data indicate that ssrA plays a role in the pathogenesis of Salmonella, serves as an attachment site for Salmonella-specific sequences, and is required for the growth of phage P22. PMID:10692360

Prevalence and characterization of multidrug-resistant (type ACSSuT) Salmonella enterica serovar Typhimurium strains in isolates from four gosling farms and a hatchery farm.

PubMed

Yu, Chang-You; Chou, Shih-Jen; Yeh, Chia-Ming; Chao, Maw-Rong; Huang, Kwo-Ching; Chang, Yung-Fu; Chiou, Chien-Shun; Weill, Francois-Xavier; Chiu, Cheng-Hsun; Chu, Chi-Hong; Chu, Chishih

2008-02-01

Salmonella enterica serovar Typhimurium strains of phage types DT104 and U302 are often resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline (the ACSSuT resistance type) and are major zoonotic pathogens. Increased consumption of goose meat may enhance the risk of transferring S. enterica serovar Typhimurium and other enteric pathogens from geese to human due to the consumption of meats from infected geese or improper preparation of meats. Therefore, we characterized S. enterica serovar Typhimurium strains isolated from four goose farms (farms A, B, C, and D) and one hatchery farm (farm E) to determine the epidemic and genetic differences among them. Antibiotic susceptibility tests and multiplex PCR confirmed that 77.6% (52/67) of strains were ACSSuT strains isolated from farms A, C, and E. Antibiotic-susceptible strains were isolated mostly from farm B, and no strain was observed in farm D. All ACSSuT strains harbored a 94.7-kb virulence plasmid and contained one 1.1-kb conserved segment identical to that of Salmonella genomic island 1. Four genotypes were determined among these S. enterica serovar Typhimurium isolates by pulsed-field gel electrophoresis analysis of XbaI-digested DNA fragments. Most isolates (85.29%; 29/34) of major genotype Ib were ACSSuT strains isolated mainly from goslings of farm C and egg membranes of farm E, a hatchery farm, suggesting that S. enterica serovar Typhimurium strains in isolates from goslings might originate from its hatchery, from the egg membranes to the gosling fluff after hatching. Multiple phage types, types 8, 12, U283, DT104, and U302, were identified. In conclusion, geese were a reservoir of diverse multidrug-resistant (type ACSSuT) S. enterica serovar Typhimurium strains, and each farm was colonized with genetically closely related S. enterica serovar Typhimurium strains.

Chlortetracycline and florfenicol induce expression of genes associated with pathogenicity in multidrug-resistant Salmonella enterica serovar Typhimurium

USDA-ARS?s Scientific Manuscript database

Background Multidrug-resistant (MDR) Salmonella enterica serovar Typhimurium (S. Typhimurium) is a serious public health threat as infections caused by these strains are more difficult and expensive to treat. Livestock serve as a reservoir for MDR Salmonella, and the antibiotics chlortetracycline an...

Impairment of Swimming Motility by Antidiarrheic Lactobacillus acidophilus Strain LB Retards Internalization of Salmonella enterica Serovar Typhimurium within Human Enterocyte-Like Cells▿

PubMed Central

Liévin-Le Moal, Vanessa; Amsellem, Raymonde; Servin, Alain L.

2011-01-01

We report that both culture and the cell-free culture supernatant (CFCS) of Lactobacillus acidophilus strain LB (Lactéol Boucard) have the ability (i) to delay the appearance of Salmonella enterica serovar Typhimurium strain SL1344-induced mobilization of F-actin and, subsequently, (ii) to retard cell entry by S. Typhimurium SL1344. Time-lapse imaging and Western immunoblotting showed that S. Typhimurium SL1344 swimming motility, as represented by cell tracks of various types, was rapidly but temporarily blocked without affecting the expression of FliC flagellar propeller protein. We show that the product(s) secreted by L. acidophilus LB that supports the inhibitory activity is heat stable and of low molecular weight. The product(s) caused rapid depolarization of the S. Typhimurium SL1344 cytoplasmic membrane without affecting bacterial viability. We identified inhibition of swimming motility as a newly discovered mechanism by which the secreted product(s) of L. acidophilus strain LB retards the internalization of the diarrhea-associated pathogen S. enterica serovar Typhimurium within cultured human enterocyte-like cells. PMID:21825295

Using In Vitro Dynamic Models To Evaluate Fluoroquinolone Activity against Emergence of Resistant Salmonella enterica Serovar Typhimurium

PubMed Central

Lee, Seung-Jin; Awji, Elias Gebru; Park, Na-hye

2016-01-01

ABSTRACT The objectives of this study were to determine pharmacokinetic/pharmacodynamic (PK/PD) indices of fluoroquinolones that minimize the emergence of resistant Salmonella enterica serovar Typhimurium (S. Typhimurium) using in vitro dynamic models and to establish mechanisms of resistance. Three fluoroquinolones, difloxacin (DIF), enrofloxacin (ENR), and marbofloxacin (MAR), at five dose levels and 3 days of treatment were simulated. Bacterial killing-regrowth kinetics and emergence of resistant bacteria after antibacterial drug exposure were quantified. PK/PD indices associated with different levels of antibacterial activity were computed. Mechanisms of fluoroquinolone resistance were determined by analyzing target mutations in the quinolone resistance-determining regions (QRDRs) and by analyzing overexpression of efflux pumps. Maximum losses in susceptibility of fluoroquinolone-exposed S. Typhimurium occurred at a simulated AUC/MIC ratio (area under the concentration-time curve over 24 h in the steady state divided by the MIC) of 47 to 71. Target mutations in gyrA (S83F) and overexpression of acrAB-tolC contributed to decreased susceptibility in fluoroquinolone-exposed S. Typhimurium. The current data suggest AUC/MIC (AUC/mutant prevention concentration [MPC])-dependent selection of resistant mutants of S. Typhimurium, with AUC/MPC ratios of 69 (DIF), 62 (ENR), and 39 (MAR) being protective against selection of resistant mutants. These values could not be achieved in veterinary clinical areas under the current recommended therapeutic doses of the fluoroquinolones, suggesting the need to reassess the current dosing regimen to include both clinical efficacy and minimization of emergence of resistant bacteria. PMID:27895011

Streptomycin Induced Stress Response in Salmonella enterica Serovar Typhimurium Shows Distinct Colony Scatter Signature

PubMed Central

Singh, Atul K.; Drolia, Rishi; Bai, Xingjian; Bhunia, Arun K.

2015-01-01

We investigated the streptomycin-induced stress response in Salmonella enterica serovars with a laser optical sensor, BARDOT (bacterial rapid detection using optical scattering technology). Initially, the top 20 S. enterica serovars were screened for their response to streptomycin at 100 μg/mL. All, but four S. enterica serovars were resistant to streptomycin. The MIC of streptomycin-sensitive serovars (Enteritidis, Muenchen, Mississippi, and Schwarzengrund) varied from 12.5 to 50 μg/mL, while streptomycin-resistant serovar (Typhimurium) from 125–250 μg/mL. Two streptomycin-sensitive serovars (Enteritidis and Mississippi) were grown on brain heart infusion (BHI) agar plates containing sub-inhibitory concentration of streptomycin (1.25–5 μg/mL) and a streptomycin-resistant serovar (Typhimurium) was grown on BHI containing 25–50 μg/mL of streptomycin and the colonies (1.2 ± 0.1 mm diameter) were scanned using BARDOT. Data show substantial qualitative and quantitative differences in the colony scatter patterns of Salmonella grown in the presence of streptomycin than the colonies grown in absence of antibiotic. Mass-spectrometry identified overexpression of chaperonin GroEL, which possibly contributed to the observed differences in the colony scatter patterns. Quantitative RT-PCR and immunoassay confirmed streptomycin-induced GroEL expression while, aminoglycoside adenylyltransferase (aadA), aminoglycoside efflux pump (aep), multidrug resistance subunit acrA, and ribosomal protein S12 (rpsL), involved in streptomycin resistance, were unaltered. The study highlights suitability of the BARDOT as a non-invasive, label-free tool for investigating stress response in Salmonella in conjunction with the molecular and immunoassay methods. PMID:26252374

Polynucleotide phosphorlyase (PNPase) is required for Salmonella enterica serovar Typhimurium colonization in swine

USDA-ARS?s Scientific Manuscript database

The pnp gene encodes polynucleotide phosphorylase, an exoribonuclease involved in RNA degradation. A mutation in the pnp gene was previously identified by our group in a signature-tagged mutagenesis screen designed to search for Salmonella enterica serovar Typhimurium genes required for survival in...

Salmonella enterica Serovar Typhimurium Exploits Inflammation to Modify Swine Intestinal Microbiota.

PubMed

Drumo, Rosanna; Pesciaroli, Michele; Ruggeri, Jessica; Tarantino, Michela; Chirullo, Barbara; Pistoia, Claudia; Petrucci, Paola; Martinelli, Nicola; Moscati, Livia; Manuali, Elisabetta; Pavone, Silvia; Picciolini, Matteo; Ammendola, Serena; Gabai, Gianfranco; Battistoni, Andrea; Pezzotti, Giovanni; Alborali, Giovanni L; Napolioni, Valerio; Pasquali, Paolo; Magistrali, Chiara F

2015-01-01

Salmonella enterica serovar Typhimurium is an important zoonotic gastrointestinal pathogen responsible for foodborne disease worldwide. It is a successful enteric pathogen because it has developed virulence strategies allowing it to survive in a highly inflamed intestinal environment exploiting inflammation to overcome colonization resistance provided by intestinal microbiota. In this study, we used piglets featuring an intact microbiota, which naturally develop gastroenteritis, as model for salmonellosis. We compared the effects on the intestinal microbiota induced by a wild type and an attenuated S. Typhimurium in order to evaluate whether the modifications are correlated with the virulence of the strain. This study showed that Salmonella alters microbiota in a virulence-dependent manner. We found that the wild type S. Typhimurium induced inflammation and a reduction of specific protecting microbiota species (SCFA-producing bacteria) normally involved in providing a barrier against pathogens. Both these effects could contribute to impair colonization resistance, increasing the host susceptibility to wild type S. Typhimurium colonization. In contrast, the attenuated S. Typhimurium, which is characterized by a reduced ability to colonize the intestine, and by a very mild inflammatory response, was unable to successfully sustain competition with the microbiota.

Salmonella enterica Serovar Typhimurium Exploits Inflammation to Modify Swine Intestinal Microbiota

PubMed Central

Drumo, Rosanna; Pesciaroli, Michele; Ruggeri, Jessica; Tarantino, Michela; Chirullo, Barbara; Pistoia, Claudia; Petrucci, Paola; Martinelli, Nicola; Moscati, Livia; Manuali, Elisabetta; Pavone, Silvia; Picciolini, Matteo; Ammendola, Serena; Gabai, Gianfranco; Battistoni, Andrea; Pezzotti, Giovanni; Alborali, Giovanni L.; Napolioni, Valerio; Pasquali, Paolo; Magistrali, Chiara F.

2016-01-01

Salmonella enterica serovar Typhimurium is an important zoonotic gastrointestinal pathogen responsible for foodborne disease worldwide. It is a successful enteric pathogen because it has developed virulence strategies allowing it to survive in a highly inflamed intestinal environment exploiting inflammation to overcome colonization resistance provided by intestinal microbiota. In this study, we used piglets featuring an intact microbiota, which naturally develop gastroenteritis, as model for salmonellosis. We compared the effects on the intestinal microbiota induced by a wild type and an attenuated S. Typhimurium in order to evaluate whether the modifications are correlated with the virulence of the strain. This study showed that Salmonella alters microbiota in a virulence-dependent manner. We found that the wild type S. Typhimurium induced inflammation and a reduction of specific protecting microbiota species (SCFA-producing bacteria) normally involved in providing a barrier against pathogens. Both these effects could contribute to impair colonization resistance, increasing the host susceptibility to wild type S. Typhimurium colonization. In contrast, the attenuated S. Typhimurium, which is characterized by a reduced ability to colonize the intestine, and by a very mild inflammatory response, was unable to successfully sustain competition with the microbiota. PMID:26835435

Variable-Number Tandem Repeats That Are Useful in Genotyping Isolates of Salmonella enterica subsp. enterica Serovars Typhimurium and Newport▿

PubMed Central

Witonski, D. ; Stefanova, R.; Ranganathan, A.; Schutze, G. E.; Eisenach, K. D.; Cave, M. D.

2006-01-01

The genome of Salmonella enterica subsp. enterica serovar Typhimurium strain LT2 was analyzed for direct repeats, and 54 sequences containing variable-number tandem repeat loci were identified. Ten primer pairs that anneal upstream and downstream of each selected locus were designed and used to amplify PCR targets in isolates of S. enterica serovars Typhimurium and Newport. Four of the 10 loci did not show polymorphism in the length of products. Six loci were selected for analysis. Isolates of S. enterica serovars Typhimurium and Newport that were related to specific outbreaks and showed identical pulsed-field gel electrophoresis patterns were indistinguishable by the length of the six variable-number tandem repeats. Isolates that differed in their pulsed-field gel electrophoresis patterns showed polymorphism in variable-number tandem repeat profiles. Length of the products was confirmed by DNA sequence analysis. Only 2 of the 10 loci contained exact integers of the direct repeat. Eight loci contained partial copies. The partial copies were maintained at the ends of the variable-number tandem repeat loci in all isolates. In spite of having partial copies that were maintained in all isolates, the number of direct repeats at a locus was polymorphic. Six variable-number tandem repeat loci were useful in distinguishing isolates of S. enterica serovars Typhimurium and Newport that had different pulsed-field gel electrophoresis patterns and in identifying outbreak-associated cases that shared a common pulsed-field gel pattern. PMID:16943354

Influence of the treatment of Listeria monocytogenes and Salmonella enterica serovar Typhimurium with citral on the efficacy of various antibiotics.

PubMed

Zanini, Surama F; Silva-Angulo, Angela B; Rosenthal, Amauri; Aliaga, Dolores Rodrigo; Martínez, Antonio

2014-04-01

The main goal of this work was to study the bacterial adaptive responses to antibiotics induced by sublethal concentration of citral on first-and second-generation cells of Listeria monocytogenes serovar 4b (CECT 4032) and Salmonella enterica serovar Typhimurium (CECT 443). The first-generation cells were not pretreated with citral, while the second-generation cells were obtained from cells previously exposed to citral during 5 h. The trials were conducted at 37°C. The presence of citral in the culture medium and the antibiotic strips resulted in a reduced minimum inhibitory concentration (MIC) for the first-generation cells of Listeria monocytogenes serovar 4b and Salmonella Typhimurium. This result was observed for almost all the antibiotics, compared with the same microorganisms of the control group (without citral), which could represent an additive effect. For Listeria serovar 4b, the second-generation cells of the test group maintained the same susceptibility to antibiotics compared with cells in the control group and in the test group of the first generation. The second-generation cells of the control group indicated that the Salmonella Typhimurium maintained the same sensitivity to the antibiotics tested compared with the first generation of this group, except in the case of erythromycin, which exhibited an increased MIC value. With respect to the second-generation cells of Salmonella Typhimurium, the presence of citral determined a decrease in the antibiotic susceptibility for almost all of the antibiotics, except colistin, compared with the first-generation of the test group, which can be seen by increase of MIC values. In conclusion, the presence of citral in the culture medium of Listeria 4b and Salmonella Typhimurium increased the antibiotic susceptibility of the first generations, while we observed an increase in antibiotic resistance in the second generation of Salmonella Typhimurium.

Genomics of an emerging clone of Salmonella serovar Typhimurium ST313 from Nigeria and the Democratic Republic of Congo.

PubMed

Leekitcharoenphon, Pimlapas; Friis, Carsten; Zankari, Ea; Svendsen, Christina Aaby; Price, Lance B; Rahmani, Maral; Herrero-Fresno, Ana; Fashae, Kayode; Vandenberg, Olivier; Aarestrup, Frank M; Hendriksen, Rene S

2013-10-15

Salmonella enterica serovar Typhimurium ST313 is an invasive and phylogenetically distinct lineage present in sub-Saharan Africa. We report the presence of S. Typhimurium ST313 from patients in the Democratic Republic of Congo and Nigeria. Eighteen S. Typhimurium ST313 isolates were characterized by antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). Additionally, six of the isolates were characterized by whole genome sequence typing (WGST). The presence of a putative virulence determinant was examined in 177 Salmonella isolates belonging to 57 different serovars. All S. Typhimurium ST313 isolates harbored resistant genes encoded by blaTEM1b, catA1, strA/B, sul1, and dfrA1. Additionally, aac(6')1aa gene was detected. Phylogenetic analyses revealed close genetic relationships among Congolese and Nigerian isolates from both blood and stool. Comparative genomic analyses identified a putative virulence fragment (ST313-TD) unique to S. Typhimurium ST313 and S. Dublin. We showed in a limited number of isolates that S. Typhimurium ST313 is a prevalent sequence-type causing gastrointestinal diseases and septicemia in patients from Nigeria and DRC. We found three distinct phylogenetic clusters based on the origin of isolation suggesting some spatial evolution. Comparative genomics showed an interesting putative virulence fragment (ST313-TD) unique to S. Typhimurium ST313 and invasive S. Dublin.

Swarm and swim motilities of Salmonella enterica serovar Typhimurium and role of osmoregulated periplasmic glucans

USDA-ARS?s Scientific Manuscript database

Background: Salmonella enterica serovar Typhimurium strains synthesize osmoregulated periplasmic glucans (OPGs) under low osmolarity conditions (< 70 mos mol l-1). OPG synthesis is not observed when cells are grown in iso- or hyper-osmotic media (> 400 mos mol l-1). Mutation in OPG structural gene...

Biofilm formation ability of Salmonella enterica serovar Typhimurium acrAB mutants.

PubMed

Schlisselberg, Dov B; Kler, Edna; Kisluk, Guy; Shachar, Dina; Yaron, Sima

2015-10-01

Recent studies offer contradictory findings about the role of multidrug efflux pumps in bacterial biofilm development. Thus, the aim of this study was to investigate the involvement of the AcrAB efflux pump in biofilm formation by investigating the ability of AcrB and AcrAB null mutants of Salmonella enterica serovar Typhimurium to produce biofilms. Three models were used to compare the ability of S. Typhimurium wild-type and its mutants to form biofilms: formation of biofilm on polystyrene surfaces; production of biofilm (mat model) on the air/liquid interface; and expression of curli and cellulose on Congo red-supplemented agar plates. All three investigated genotypes formed biofilms with similar characteristics. However, upon exposure to chloramphenicol, formation of biofilms on solid surfaces as well as the production of curli were either reduced or were delayed more significantly in both mutants, whilst there was no visible effect on pellicle formation. It can be concluded that when no selective pressure is applied, S. Typhimurium is able to produce biofilms even when the AcrAB efflux pumps are inactivated, implying that the use of efflux pump inhibitors to prevent biofilm formation is not a general solution and that combined treatments might be more efficient. Other factors that affect the ability to produce biofilms depending on efflux pump activity are yet to be identified. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Development of a LIBS assay for the detection of Salmonella enterica serovar Typhimurium from food.

PubMed

Barnett, Cleon; Bell, Courtneé; Vig, Komal; Akpovo, A C; Johnson, Lewis; Pillai, Shreekumar; Singh, Shree

2011-07-01

Laser-induced breakdown spectroscopy (LIBS) is used for the identification of the presence of hazardous bacteria in food. In this study, our main focus was centered on the identification of S. enterica serovar Typhimurium, a Gram-negative foodborne pathogen, in various liquids such as milk, chicken broth, and brain heart infusion due to the infection being most prevalent in raw meat and dairy products. A Nd:YAG laser of operating wavelength 266 nm was used to obtain the spectra from the artificially inoculated liquid samples. A series of experiments were performed to determine the effectiveness of LIBS to discriminate the bacteria from the background liquids. These results are compared with competing modern molecular methods of detection which include polymerase chain reaction (PCR) and quantitative real-time PCR. In addition to analyzing S. enterica serovar Typhimurium, another common Gram-negative, Escherichia coli, as well as Gram-positive pathogen, Staphlycoccus auerus, were used to determine the specificity of the LIBS technique.

Genomic diversity and adaptation of Salmonella enterica serovar Typhimurium from analysis of six genomes of different phage types

PubMed Central

2013-01-01

Background Salmonella enterica serovar Typhimurium (or simply Typhimurium) is the most common serovar in both human infections and farm animals in Australia and many other countries. Typhimurium is a broad host range serovar but has also evolved into host-adapted variants (i.e. isolated from a particular host such as pigeons). Six Typhimurium strains of different phage types (defined by patterns of susceptibility to lysis by a set of bacteriophages) were analysed using Illumina high-throughput genome sequencing. Results Variations between strains were mainly due to single nucleotide polymorphisms (SNPs) with an average of 611 SNPs per strain, ranging from 391 SNPs to 922 SNPs. There were seven insertions/deletions (indels) involving whole or partial gene deletions, four inactivation events due to IS200 insertion and 15 pseudogenes due to early termination. Four of these inactivated or deleted genes may be virulence related. Nine prophage or prophage remnants were identified in the six strains. Gifsy-1, Gifsy-2 and the sopE2 and sspH2 phage remnants were present in all six genomes while Fels-1, Fels-2, ST64B, ST104 and CP4-57 were variably present. Four strains carried the 90-kb plasmid pSLT which contains several known virulence genes. However, two strains were found to lack the plasmid. In addition, one strain had a novel plasmid similar to Typhi strain CT18 plasmid pHCM2. Conclusion The genome data suggest that variations between strains were mainly due to accumulation of SNPs, some of which resulted in gene inactivation. Unique genetic elements that were common between host-adapted phage types were not found. This study advanced our understanding on the evolution and adaptation of Typhimurium at genomic level. PMID:24138507

Comparison of Salmonella enterica Serovars Typhi and Typhimurium Reveals Typhoidal Serovar-Specific Responses to Bile

PubMed Central

Johnson, Rebecca; Ravenhall, Matt; Pickard, Derek; Dougan, Gordon; Byrne, Alexander

2017-01-01

ABSTRACT Salmonella enterica serovars Typhi and Typhimurium cause typhoid fever and gastroenteritis, respectively. A unique feature of typhoid infection is asymptomatic carriage within the gallbladder, which is linked with S. Typhi transmission. Despite this, S. Typhi responses to bile have been poorly studied. Transcriptome sequencing (RNA-Seq) of S. Typhi Ty2 and a clinical S. Typhi isolate belonging to the globally dominant H58 lineage (strain 129-0238), as well as S. Typhimurium 14028, revealed that 249, 389, and 453 genes, respectively, were differentially expressed in the presence of 3% bile compared to control cultures lacking bile. fad genes, the actP-acs operon, and putative sialic acid uptake and metabolism genes (t1787 to t1790) were upregulated in all strains following bile exposure, which may represent adaptation to the small intestine environment. Genes within the Salmonella pathogenicity island 1 (SPI-1), those encoding a type IIII secretion system (T3SS), and motility genes were significantly upregulated in both S. Typhi strains in bile but downregulated in S. Typhimurium. Western blots of the SPI-1 proteins SipC, SipD, SopB, and SopE validated the gene expression data. Consistent with this, bile significantly increased S. Typhi HeLa cell invasion, while S. Typhimurium invasion was significantly repressed. Protein stability assays demonstrated that in S. Typhi the half-life of HilD, the dominant regulator of SPI-1, is three times longer in the presence of bile; this increase in stability was independent of the acetyltransferase Pat. Overall, we found that S. Typhi exhibits a specific response to bile, especially with regard to virulence gene expression, which could impact pathogenesis and transmission. PMID:29229736

mcr-1−Harboring Salmonella enterica Serovar Typhimurium Sequence Type 34 in Pigs, China

PubMed Central

Yi, Linxian; Wang, Jing; Gao, Yanling; Liu, Yiyun; Doi, Yohei; Wu, Renjie; Zeng, Zhenling; Liang, Zisen

2017-01-01

We detected the mcr-1 gene in 21 (14.8%) Salmonella isolates from pigs at slaughter; 19 were serovar Typhimurium sequence type 34. The gene was located on IncHI2-like plasmids that also harbored IncF replicons and lacked a conjugative transfer region. These findings highlight the need to prevent further spread of colistin resistance in animals and humans. PMID:28098547

Resuscitation by Ferrioxamine E of Stressed Salmonella enterica Serovar Typhimurium from Soil and Water Microcosms

PubMed Central

Reissbrodt, R.; Heier, H.; Tschäpe, H.; Kingsley, R. A.; Williams, P. H.

2000-01-01

Storage of Salmonella enterica serovar Typhimurium strains in soil and water microcosms resulted in loss of culturability on standard plating media. Prior incubation in buffered peptone water supplemented with ferrioxamine E markedly extended the time that bacteria were recoverable by plating, except in the case of mutants deficient in ferrioxamine E uptake. PMID:10966440

Oxidoreductases that Act as Conditional Virulence Suppressors in Salmonella enterica Serovar Typhimurium

PubMed Central

Anwar, Naeem; Sem, Xiao Hui; Rhen, Mikael

2013-01-01

In Salmonella enterica serovar Typhimurium, oxidoreductases of the thioredoxin superfamily contribute to bacterial invasiveness, intracellular replication and to the virulence in BALB/c mice as well as in the soil nematode Caenorhabditis elegans. The scsABCD gene cluster, present in many but not all enteric bacteria, codes for four putative oxidoreductases of the thioredoxin superfamily. Here we have analyzed the potential role of the scs genes in oxidative stress tolerance and virulence in S. Typhimurium. An scsABCD deletion mutant showed moderate sensitization to the redox-active transition metal ion copper and increased protein carbonylation upon exposure to hydrogen peroxide. Still, the scsABCD mutant was not significantly affected for invasiveness or intracellular replication in respectively cultured epithelial or macrophage-like cells. However, we noted a significant copper chloride sensitivity of SPI1 T3SS mediated invasiveness that strongly depended on the presence of the scs genes. The scsABCD deletion mutant was not attenuated in animal infection models. In contrast, the mutant showed a moderate increase in its competitive index upon intraperitoneal challenge and enhanced invasiveness in small intestinal ileal loops of BALB/c mice. Moreover, deletion of the scsABCD genes restored the invasiveness of a trxA mutant in epithelial cells and its virulence in C. elegans. Our findings thus demonstrate that the scs gene cluster conditionally affects virulence and underscore the complex interactions between oxidoreductases of the thioredoxin superfamily in maintaining host adaptation of S. Typhimurium. PMID:23750221

Transcriptomic analysis of swarm motility phenotype of Salmonella enterica serovar Typhimurium mutant defective in periplasmic glucan synthesis

USDA-ARS?s Scientific Manuscript database

Movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. Salmonella enterica serovar Typhimurium mutants defective in OPG synthesis are unable to exhibit motility on moist surfaces (swarming) ...

Evaluation of a Multiplex PCR Assay for the Identification of Salmonella Serovars Enteritidis and Typhimurium Using Retail and Abattoir Samples.

PubMed

Ogunremi, Dele; Nadin-Davis, Susan; Dupras, Andrée Ann; Márquez, Imelda Gálvan; Omidi, Katayoun; Pope, Louise; Devenish, John; Burke, Teresa; Allain, Ray; Leclair, Daniel

2017-02-01

A multiplex PCR was developed to identify the two most common serovars of Salmonella causing foodborne illness in Canada, namely, serovars Enteritidis and Typhimurium. The PCR was designed to amplify DNA fragments from four Salmonella genes, namely, invA gene (211-bp fragment), iroB gene (309-bp fragment), Typhimurium STM 4497 (523-bp fragment), and Enteritidis SE147228 (612-bp fragment). In addition, a 1,026-bp ribosomal DNA (rDNA) fragment universally present in bacterial species was included in the assay as an internal control fragment. The detection rate of the PCR was 100% among Salmonella Enteritidis (n = 92) and Salmonella Typhimurium (n = 33) isolates. All tested Salmonella isolates (n = 194) were successfully identified based on the amplification of at least one Salmonella -specific DNA fragment. None of the four Salmonella DNA amplicons were detected in any of the non- Salmonella isolates (n = 126), indicating an exclusivity rate of 100%. When applied to crude extracts of 2,001 field isolates of Salmonella obtained during the course of a national microbiological baseline study in broiler chickens and chicken products sampled from abattoir and retail outlets, 163 isolates, or 8.1%, tested positive for Salmonella Enteritidis and another 80 isolates, or 4.0%, tested as Salmonella Typhimurium. All isolates identified by serological testing as Salmonella Enteritidis in the microbiological study were also identified by using the multiplex PCR. The new test can be used to identify or confirm pure isolates of the two serovars and is also amenable for integration into existing culture procedures for accurate detection of Salmonella colonies.

Whole genome sequencing of multidrug-resistant Salmonella enterica serovar Typhimurium isolated from humans and poultry in Burkina Faso

USDA-ARS?s Scientific Manuscript database

Background. Multidrug-resistant Salmonella is an important cause of morbidity and mortality in developing countries. The aim of this study was to characterize and compare multidrug-resistant Salmonella enterica serovar Typhimurium isolates from patients and poultry feces. Methods. Salmonella strains...

The Salmonella enterica serovar Typhimurium QseB Response Regulator Negatively Regulates Bacterial Motility and Swine Colonization in the Absence of the QseC Sensor Kinase

USDA-ARS?s Scientific Manuscript database

Salmonella enterica serovar Typhimurium (S. Typhimurium) responds to the catecholamine, norepinephrine by increasing bacterial growth and enhancing motility. In this study, iron with or without the siderophore, ferrioxamine E also enhanced bacterial motility. Iron-enhanced motility was growth-rate ...

Role of anionic charges of osmoregulated periplasmic glucans of Salmonella enterica Serovar Typhimurium SL1344 in mice virulence

USDA-ARS?s Scientific Manuscript database

Osmoregulated periplasmic glucans (OPGs) are important periplasmic constituents of Salmonella spp. and are required for optimal growth in hypoosmotic environments such as irrigation and vegetable wash waters as well as for mice virulence. opgB gene of Salmonella enterica serovar Typhimurium was ide...

BcsZ inhibits biofilm phenotypes and promotes virulence by blocking cellulose production in Salmonella enterica serovar Typhimurium.

PubMed

Ahmad, Irfan; Rouf, Syed Fazle; Sun, Lei; Cimdins, Annika; Shafeeq, Sulman; Le Guyon, Soazig; Schottkowski, Marco; Rhen, Mikael; Römling, Ute

2016-10-19

Cellulose, a 1,4 beta-glucan polysaccharide, is produced by a variety of organisms including bacteria. Although the production of cellulose has a high biological, ecological and economical impact, regulatory mechanisms of cellulose biosynthesis are mostly unknown. Family eight cellulases are regularly associated with cellulose biosynthesis operons in bacteria; however, their function is poorly characterized. In this study, we analysed the role of the cellulase BcsZ encoded by the bcsABZC cellulose biosynthesis operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) in biofilm related behavior. We also investigated the involvement of BcsZ in pathogenesis of S. Typhimurium including a murine typhoid fever infection model. In S. Typhimurium, cellulase BcsZ with a putative periplasmic location negatively regulates cellulose biosynthesis. Moreover, as assessed with a non-polar mutant, BcsZ affects cellulose-associated phenotypes such as the rdar biofilm morphotype, cell clumping, biofilm formation, pellicle formation and flagella-dependent motility. Strikingly, although upregulation of cellulose biosynthesis was not observed on agar plate medium at 37 °C, BcsZ is required for efficient pathogen-host interaction. Key virulence phenotypes of S. Typhimurium such as invasion of epithelial cells and proliferation in macrophages were positively regulated by BcsZ. Further on, a bcsZ mutant was outcompeted by the wild type in organ colonization in the murine typhoid fever infection model. Selected phenotypes were relieved upon deletion of the cellulose synthase BcsA and/or the central biofilm activator CsgD. Although the protein scaffold has an additional physiological role, our findings indicate that the catalytic activity of BcsZ effectively downregulates CsgD activated cellulose biosynthesis. Repression of cellulose production by BcsZ subsequently enables Salmonella to efficiently colonize the host.

Genomic Variability of Serial Human Isolates of Salmonella enterica Serovar Typhimurium Associated with Prolonged Carriage.

PubMed

Octavia, Sophie; Wang, Qinning; Tanaka, Mark M; Sintchenko, Vitali; Lan, Ruiting

2015-11-01

Salmonella enterica serovar Typhimurium is an important foodborne human pathogen that often causes self-limiting but severe gastroenteritis. Prolonged excretion of S. Typhimurium after the infection can lead to secondary transmissions. However, little is known about within-host genomic variation in bacteria associated with asymptomatic shedding. Genomes of 35 longitudinal isolates of S. Typhimurium recovered from 11 patients (children and adults) with culture-confirmed gastroenteritis were sequenced. There were three or four isolates obtained from each patient. Single nucleotide polymorphisms (SNPs) were analyzed in these isolates, which were recovered between 1 and 279 days after the initial diagnosis. Limited genomic variation (5 SNPs or fewer) was associated with short- and long-term carriage of S. Typhimurium. None of the isolates was shown to be due to reinfection. SNPs occurred randomly, and the majority of the SNPs were nonsynonymous. Two nonsense mutations were observed. A nonsense mutation in flhC rendered the isolate nonmotile, whereas the significance of a nonsense mutation in yihV is unknown. The estimated mutation rate is 1.49 × 10(-6) substitution per site per year. S. Typhimurium isolates excreted in stools following acute gastroenteritis in children and adults demonstrated limited genomic variability over time, regardless of the duration of carriage. These findings have important implications for the detection of possible transmission events suspected by public health genomic surveillance of S. Typhimurium infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Beneficial Effects of Sodium Phenylbutyrate Administration during Infection with Salmonella enterica Serovar Typhimurium.

PubMed

Jellbauer, Stefan; Perez Lopez, Araceli; Behnsen, Judith; Gao, Nina; Nguyen, Thao; Murphy, Clodagh; Edwards, Robert A; Raffatellu, Manuela

2016-09-01

Sodium phenylbutyrate (PBA) is a derivative of the short-chain fatty acid butyrate and is approved for treatment of urea cycle disorders and progressive familial intrahepatic cholestasis type 2. Previously known functions include histone deacetylase inhibitor, endoplasmic reticulum stress inhibitor, ammonia sink, and chemical chaperone. Here, we show that PBA has a previously undiscovered protective role in host mucosal defense during infection. Administration of PBA to Taconic mice resulted in the increase of intestinal Lactobacillales and segmented filamentous bacteria (SFB), as well as an increase of interleukin 17 (IL-17) production by intestinal cells. This effect was not observed in Jackson Laboratory mice, which are not colonized with SFB. Because previous studies showed that IL-17 plays a protective role during infection with mucosal pathogens, we hypothesized that Taconic mice treated with PBA would be more resistant to infection with Salmonella enterica serovar Typhimurium (S Typhimurium). By using the streptomycin-treated mouse model, we found that Taconic mice treated with PBA exhibited significantly lower S Typhimurium intestinal colonization and dissemination to the reticuloendothelial system, as well as lower levels of inflammation. The lower levels of S Typhimurium gut colonization and intestinal inflammation were not observed in Jackson Laboratory mice. Although PBA had no direct effect on bacterial replication, its administration reduced S Typhimurium epithelial cell invasion and lowered the induction of the proinflammatory cytokine IL-23 in macrophage-like cells. These effects likely contributed to the better outcome of infection in PBA-treated mice. Overall, our results suggest that PBA induces changes in the microbiota and in the mucosal immune response that can be beneficial to the host during infection with S Typhimurium and possibly other enteric pathogens. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Beneficial Effects of Sodium Phenylbutyrate Administration during Infection with Salmonella enterica Serovar Typhimurium

PubMed Central

Jellbauer, Stefan; Perez Lopez, Araceli; Behnsen, Judith; Gao, Nina; Nguyen, Thao; Murphy, Clodagh; Edwards, Robert A.

2016-01-01

Sodium phenylbutyrate (PBA) is a derivative of the short-chain fatty acid butyrate and is approved for treatment of urea cycle disorders and progressive familial intrahepatic cholestasis type 2. Previously known functions include histone deacetylase inhibitor, endoplasmic reticulum stress inhibitor, ammonia sink, and chemical chaperone. Here, we show that PBA has a previously undiscovered protective role in host mucosal defense during infection. Administration of PBA to Taconic mice resulted in the increase of intestinal Lactobacillales and segmented filamentous bacteria (SFB), as well as an increase of interleukin 17 (IL-17) production by intestinal cells. This effect was not observed in Jackson Laboratory mice, which are not colonized with SFB. Because previous studies showed that IL-17 plays a protective role during infection with mucosal pathogens, we hypothesized that Taconic mice treated with PBA would be more resistant to infection with Salmonella enterica serovar Typhimurium (S. Typhimurium). By using the streptomycin-treated mouse model, we found that Taconic mice treated with PBA exhibited significantly lower S. Typhimurium intestinal colonization and dissemination to the reticuloendothelial system, as well as lower levels of inflammation. The lower levels of S. Typhimurium gut colonization and intestinal inflammation were not observed in Jackson Laboratory mice. Although PBA had no direct effect on bacterial replication, its administration reduced S. Typhimurium epithelial cell invasion and lowered the induction of the proinflammatory cytokine IL-23 in macrophage-like cells. These effects likely contributed to the better outcome of infection in PBA-treated mice. Overall, our results suggest that PBA induces changes in the microbiota and in the mucosal immune response that can be beneficial to the host during infection with S. Typhimurium and possibly other enteric pathogens. PMID:27382022

Proteomic analysis of intestinal mucosa responses to Salmonella enterica serovar typhimurium in naturally infected pig.

PubMed

Arce, C; Lucena, C; Moreno, A; Garrido, J J

2014-01-01

Salmonella enterica serovar typhimurium (S. typhimurium) is one of the most frequent Salmonella serotypes isolated from European pigs. Despite the advances in understanding the mechanisms involved in host-pathogen interactions and host cell responses to S. typhimurium, the global change that occurs in naturally exposed populations has been poorly characterized. Here, we present a proteomics study on intestinal mucosa of pigs naturally infected with S. typhimurium, in order to better understand the pathogenesis of salmonellosis and the pathways which might be affected after infection. Samples were analyzed by 2D-DIGE and 44 different proteins exhibited statistically significant differences. The data set was analyzed by employing the Ingenuity Pathway Analysis and the physiological function most significantly perturbed were immunological and infectious disease, cellular assembly and organization and metabolism. The pathways implicated in the porcine immune response to S. typhimurium were gluconeogenesis and Rho GDI/RhoA signaling, and our results suggest that keratins and the intermediate filaments could play an important role in the damage of the mucosa and in the success of infection. The role of these findings in salmonellosis has been discussed, as well as the importance of analyzing naturally infected animals to have a complete picture of the infection. Also, we compared the results found in this work with those obtained in a similar study using experimentally infected animals. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Mutation in the PoxA Gene of Salmonella enterica Serovar Typhimurium Results in Altered Protein Production, Elevated Susceptibility to Environmental Challenges, and Decreased Swine Colonization

USDA-ARS?s Scientific Manuscript database

Using signature-tagged mutagenesis of Salmonella enterica serovar Typhimurium (S. Typhimurium), a mutation in the poxA gene (STM4344; yjeA; poxR), encoding a putative lysyl-tRNA synthetase, was previously identified by our research group which caused decreased survival in an ex vivo swine stomach co...

Toll-Like Receptor Activation by Generalized Modules for Membrane Antigens from Lipid A Mutants of Salmonella enterica Serovars Typhimurium and Enteritidis.

PubMed

Rossi, Omar; Caboni, Mariaelena; Negrea, Aurel; Necchi, Francesca; Alfini, Renzo; Micoli, Francesca; Saul, Allan; MacLennan, Calman A; Rondini, Simona; Gerke, Christiane

2016-04-01

Invasive nontyphoidal Salmonella (iNTS) disease is a neglected disease with high mortality in children and HIV-positive individuals in sub-Saharan Africa, caused primarily by Africa-specific strains of Salmonella enterica serovars Typhimurium and Enteritidis. A vaccine using GMMA (generalized modules for membrane antigens) fromS.Typhimurium andS.Enteritidis containing lipid A modifications to reduce potential in vivo reactogenicity is under development. GMMA with penta-acylated lipid A showed the greatest reduction in the level of cytokine release from human peripheral blood monocytes from that for GMMA with wild-type lipid A. Deletion of the lipid A modification genes msbB and pagP was required to achieve pure penta-acylation. Interestingly, ΔmsbBΔ pagP GMMA from S. Enteritidis had a slightly higher stimulatory potential than those from S. Typhimurium, a finding consistent with the higher lipopolysaccharide (LPS) content and Toll-like receptor 2 (TLR2) stimulatory potential of the former. Also, TLR5 ligand flagellin was found in Salmonella GMMA. No relevant contribution to the stimulatory potential of GMMA was detected even when the flagellin protein FliC from S. Typhimurium was added at a concentration as high as 10% of total protein, suggesting that flagellin impurities are not a major factor for GMMA-mediated immune stimulation. Overall, the stimulatory potential of S. Typhimurium and S. Enteritidis ΔmsbB ΔpagP GMMA was close to that of Shigella sonnei GMMA, which are currently in phase I clinical trials. Copyright © 2016 Rossi et al.

Modulation of systemic and mucosal immunity against an inactivated vaccine of Newcastle disease virus by oral co-administration of live attenuated Salmonella enterica serovar Typhimurium expressing chicken interleukin-18 and interferon-α

PubMed Central

RAHMAN, Md. Masudur; UYANGAA, Erdenebelig; HAN, Young Woo; HUR, Jin; PARK, Sang-Youel; LEE, John Hwa; KIM, Koanhoi; EO, Seong Kug

2014-01-01

Newcastle disease (ND) is a highly contagious disease of chickens causing significant economic losses worldwide. Due to limitations in the efficacy against currently circulating ND viruses, existing vaccination strategies require improvements, and incorporating immunomodulatory cytokines with existing vaccines might be a novel approach. Here, we investigated the systemic and mucosal immunomodulatory properties of oral co-administration of chicken interleukin-18 (chIL-18) and chicken interferon-α (chIFN-α) using attenuated Salmonella enterica serovar Typhimurium on an inactivated ND vaccine. Our results demonstrate that oral administration of S. enterica serovar Typhimurium expressing chIL-18 or chIFN-α provided enhanced systemic and mucosal immune responses, as determined by serum hemagglutination inhibition antibody and NDV Ag-specific IgG as well as NDV Ag-specific IgA in lung and duodenal lavages of chickens immunized with inactivated ND vaccine via the intramuscular or intranasal route. Notably, combined oral administration of S. enterica serovar Typhimurium expressing chIL-18 and chIFN-α significantly enhanced systemic and mucosal immunity in ND-vaccinated chickens, compared to single administration of S. enterica serovar Typhimurium expressing chIL-18 or chIFN-α. In addition, oral co-administration of S. enterica serovar Typhimurium expressing chIL-18 and chIFN-α provided enhanced NDV Ag-specific proliferation of peripheral blood mononuclear cells and Th1-biased cell-mediated immunity, compared to single administration of either construct. Therefore, our results provide valuable insight into the modulation of systemic and mucosal immunity by incorporation of immunomodulatory chIL-18 and chIFN-α using Salmonella vaccines into existing ND vaccines. PMID:25502364

Early immune response following Salmonella enterica subspecies enterica serovar Typhimurium infection in porcine jejunal gut loops

PubMed Central

Meurens, François; Berri, Mustapha; Auray, Gael; Melo, Sandrine; Levast, Benoît; Virlogeux-Payant, Isabelle; Chevaleyre, Claire; Gerdts, Volker; Salmon, Henri

2009-01-01

Salmonella enterica subspecies enterica serovar Typhimurium, commonly called S. Typhimurium, can cause intestinal infections in humans and various animal species such as swine. To analyze the host response to Salmonella infection in the pig we used an in vivo gut loop model, which allows the analysis of multiple immune responses within the same animal. Four jejunal gut-loops were each inoculated with 3×108 cfu of S. Typhimurium in 3 one-month-old piglets and mRNA expressions of various cytokines, chemokines, transcription factors, antimicrobial peptides, toll like and chemokine receptors were assessed by quantitative real-time PCR in the Peyer’s patch and the gut wall after 24 h. Several genes such as the newly cloned CCRL1/CCX-CKR were assessed for the first time in the pig at the mRNA level. Pro-inflammatory and T-helper type-1 (Th1) cytokine mRNA were expressed at higher levels in infected compared to non-infected control loops. Similarly, some B cell activation genes, NOD2 and toll like receptor 2 and 4 transcripts were more expressed in both tissues while TLR5 mRNA was down-regulated. Interestingly, CCL25 mRNA expression as well as the mRNA expressions of its receptors CCR9 and CCRL1 were decreased both in the Peyer’s patch and gut wall suggesting a potential Salmonella strategy to reduce lymphocyte homing to the intestine. In conclusion, these results provide insight into the porcine innate mucosal immune response to infection with entero-invasive microorganisms such as S. Typhimurium. In the future, this knowledge should help in the development of improved prophylactic and therapeutic approaches against porcine intestinal S. Typhimurium infections. PMID:18922229

Respiratory Hydrogen Use by Salmonella enterica Serovar Typhimurium Is Essential for Virulence

PubMed Central

Maier, R. J.; Olczak, A.; Maier, S.; Soni, S.; Gunn, J.

2004-01-01

Based on available annotated gene sequence information, the enteric pathogen salmonella, like other enteric bacteria, contains three putative membrane-associated H2-using hydrogenase enzymes. These enzymes split molecular H2, releasing low-potential electrons that are used to reduce quinone or heme-containing components of the respiratory chain. Here we show that each of the three distinct membrane-associated hydrogenases of Salmonella enterica serovar Typhimurium is coupled to a respiratory pathway that uses oxygen as the terminal electron acceptor. Cells grown in a blood-based medium expressed four times the amount of hydrogenase (H2 oxidation) activity that cells grown on Luria Bertani medium did. Cells suspended in phosphate-buffered saline consumed 2 mol of H2 per mol of O2 used in the H2-O2 respiratory pathway, and the activity was inhibited by the respiration inhibitor cyanide. Molecular hydrogen levels averaging over 40 μM were measured in organs (i.e., livers and spleens) of live mice, and levels within the intestinal tract (the presumed origin of the gas) were four times greater than this. The half-saturation affinity of S. enterica serovar Typhimurium for H2 is only 2.1 μM, so it is expected that H2-utilizing hydrogenase enzymes are saturated with the reducing substrate in vivo. All three hydrogenase enzymes contribute to the virulence of the bacterium in a typhoid fever-mouse model, based on results from strains with mutations in each of the three hydrogenase genes. The introduced mutations are nonpolar, and growth of the mutant strains was like that of the parent strain. The combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast to the parent strain) one that is unable to invade liver or spleen tissue. The introduction of one of the hydrogenase genes into the triple mutant strain on a low-copy-number plasmid resulted in a strain that was able to both oxidize H2 and cause morbidity in mice within 11 days of

Respiratory hydrogen use by Salmonella enterica serovar Typhimurium is essential for virulence.

PubMed

Maier, R J; Olczak, A; Maier, S; Soni, S; Gunn, J

2004-11-01

Based on available annotated gene sequence information, the enteric pathogen salmonella, like other enteric bacteria, contains three putative membrane-associated H2-using hydrogenase enzymes. These enzymes split molecular H2, releasing low-potential electrons that are used to reduce quinone or heme-containing components of the respiratory chain. Here we show that each of the three distinct membrane-associated hydrogenases of Salmonella enterica serovar Typhimurium is coupled to a respiratory pathway that uses oxygen as the terminal electron acceptor. Cells grown in a blood-based medium expressed four times the amount of hydrogenase (H2 oxidation) activity that cells grown on Luria Bertani medium did. Cells suspended in phosphate-buffered saline consumed 2 mol of H2 per mol of O2 used in the H2-O2 respiratory pathway, and the activity was inhibited by the respiration inhibitor cyanide. Molecular hydrogen levels averaging over 40 microM were measured in organs (i.e., livers and spleens) of live mice, and levels within the intestinal tract (the presumed origin of the gas) were four times greater than this. The half-saturation affinity of S. enterica serovar Typhimurium for H2 is only 2.1 microM, so it is expected that H2-utilizing hydrogenase enzymes are saturated with the reducing substrate in vivo. All three hydrogenase enzymes contribute to the virulence of the bacterium in a typhoid fever-mouse model, based on results from strains with mutations in each of the three hydrogenase genes. The introduced mutations are nonpolar, and growth of the mutant strains was like that of the parent strain. The combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast to the parent strain) one that is unable to invade liver or spleen tissue. The introduction of one of the hydrogenase genes into the triple mutant strain on a low-copy-number plasmid resulted in a strain that was able to both oxidize H2 and cause morbidity in mice within 11

Mesenteric Lymph Nodes Confine Dendritic Cell-Mediated Dissemination of Salmonella enterica Serovar Typhimurium and Limit Systemic Disease in Mice▿

PubMed Central

Voedisch, Sabrina; Koenecke, Christian; David, Sascha; Herbrand, Heike; Förster, Reinhold; Rhen, Mikael; Pabst, Oliver

2009-01-01

In humans with typhoid fever or in mouse strains susceptible to Salmonella enterica serovar Typhimurium (S. Typhimurium) infection, bacteria gain access to extraintestinal tissues, causing severe systemic disease. Here we show that in the gut-draining mesenteric lymph nodes (MLN), the majority of S. Typhimurium-carrying cells show dendritic-cell (DC) morphology and express the DC marker CD11c, indicating that S. Typhimurium bacteria are transported to the MLN by migratory DCs. In vivo FLT-3L-induced expansion of DCs, as well as stimulation of DC migration by Toll-like receptor agonists, results in increased numbers of S. Typhimurium bacteria reaching the MLN. Conversely, genetically impaired DC migration in chemokine receptor CCR7-deficient mice reduces the number of S. Typhimurium bacteria reaching the MLN. This indicates that transport of S. Typhimurium from the intestine into the MLN is limited by the number of migratory DCs carrying S. Typhimurium bacteria. In contrast, modulation of DC migration does not affect the number of S. Typhimurium bacteria reaching systemic tissues, indicating that DC-bound transport of S. Typhimurium does not substantially contribute to systemic S. Typhimurium infection. Surgical removal of the MLN results in increased numbers of S. Typhimurium bacteria reaching systemic sites early after infection, thereby rendering otherwise resistant mice susceptible to fatal systemic disease development. This suggests that the MLN provide a vital barrier shielding systemic compartments from DC-mediated dissemination of S. Typhimurium. Thus, confinement of S. Typhimurium in gut-associated lymphoid tissue and MLN delays massive extraintestinal dissemination and at the same time allows for the establishment of protective adaptive immune responses. PMID:19506012

Determination of O:4 antigen-antibody affinity level in O:5 antigen positive and negative variants of Salmonella enterica serovar Typhimurium.

PubMed

Nakai, Yuka; Ito, Akihisa; Ogawa, Yohsuke; Aribam, Swarmistha Devi; Elsheimer-Matulova, Marta; Shiraiwa, Kazumasa; Kisaka, Stevens M B; Hikono, Hirokazu; Nishikawa, Sayaka; Akiba, Masato; Kawahara, Kazuyoshi; Shimoji, Yoshihiro; Eguchi, Masahiro

2017-04-01

Salmonella enterica serovar Typhimurium (S. Typhimurium) has two serological variants: one that expresses the O:5 antigen (1,4,5,12:i:1,2) and one that lacks O:5 antigen (1,4,12:i:1,2). For serotyping, S. Typhimurium is agglutinated by diagnostic O:4 antigen serum. This study was carried out to compare the antigen-antibody affinity of O:4 antigen in S. Typhimurium χ3306 O:5-positive and S. Typhimurium χ3306 O:5-negative strains. The affinity of O:4 antigen with O:4 antigen serum was found to be stronger in the O:5-negative strains compared to O:5-positive strains. Next, we investigated the antigen-antibody affinity of O:4 antigen with O:4 antigen serum in field strains of S. Typhimurium, which showed the same tendency in affinity as seen with S. Typhimurium χ3306 O:5-positive and negative strains. This study suggests that the presence or absence of O:5 antigen causes differences in O:4 agglutination reactions with different field strains of S. Typhimurium. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Receptor Diversity and Host Interaction of Bacteriophages Infecting Salmonella enterica Serovar Typhimurium

PubMed Central

Kim, Hyeryen; Choi, Younho; Heu, Sunggi; Ryu, Sangryeol

2012-01-01

Background Salmonella enterica subspecies enterica serovar Typhimurium is a Gram-negative pathogen causing salmonellosis. Salmonella Typhimurium-targeting bacteriophages have been proposed as an alternative biocontrol agent to antibiotics. To further understand infection and interaction mechanisms between the host strains and the bacteriophages, the receptor diversity of these phages needs to be elucidated. Methodology/Principal Findings Twenty-five Salmonella phages were isolated and their receptors were identified by screening a Tn5 random mutant library of S. Typhimurium SL1344. Among them, three types of receptors were identified flagella (11 phages), vitamin B12 uptake outer membrane protein, BtuB (7 phages) and lipopolysaccharide-related O-antigen (7 phages). TEM observation revealed that the phages using flagella (group F) or BtuB (group B) as a receptor belong to Siphoviridae family, and the phages using O-antigen of LPS as a receptor (group L) belong to Podoviridae family. Interestingly, while some of group F phages (F-I) target FliC host receptor, others (F-II) target both FliC and FljB receptors, suggesting that two subgroups are present in group F phages. Cross-resistance assay of group B and L revealed that group L phages could not infect group B phage-resistant strains and reversely group B phages could not infect group L SPN9TCW-resistant strain. Conclusions/Significance In this report, three receptor groups of 25 newly isolated S. Typhimurium-targeting phages were determined. Among them, two subgroups of group F phages interact with their host receptors in different manner. In addition, the host receptors of group B or group L SPN9TCW phages hinder other group phage infection, probably due to interaction between receptors of their groups. This study provides novel insights into phage-host receptor interaction for Salmonella phages and will inform development of optimal phage therapy for protection against Salmonella. PMID:22927964

Regulation of Flagellum Biosynthesis in Response to Cell Envelope Stress in Salmonella enterica Serovar Typhimurium

PubMed Central

2018-01-01

ABSTRACT Flagellum-driven motility of Salmonella enterica serovar Typhimurium facilitates host colonization. However, the large extracellular flagellum is also a prime target for the immune system. As consequence, expression of flagella is bistable within a population of Salmonella, resulting in flagellated and nonflagellated subpopulations. This allows the bacteria to maximize fitness in hostile environments. The degenerate EAL domain protein RflP (formerly YdiV) is responsible for the bistable expression of flagella by directing the flagellar master regulatory complex FlhD4C2 with respect to proteolytic degradation. Information concerning the environmental cues controlling expression of rflP and thus about the bistable flagellar biosynthesis remains ambiguous. Here, we demonstrated that RflP responds to cell envelope stress and alterations of outer membrane integrity. Lipopolysaccharide (LPS) truncation mutants of Salmonella Typhimurium exhibited increasing motility defects due to downregulation of flagellar gene expression. Transposon mutagenesis and genetic profiling revealed that σ24 (RpoE) and Rcs phosphorelay-dependent cell envelope stress response systems sense modifications of the lipopolysaccaride, low pH, and activity of the complement system. This subsequently results in activation of RflP expression and degradation of FlhD4C2 via ClpXP. We speculate that the presence of diverse hostile environments inside the host might result in cell envelope damage and would thus trigger the repression of resource-costly and immunogenic flagellum biosynthesis via activation of the cell envelope stress response. PMID:29717015

A temporal study of Salmonella serovars in animals in Alberta between 1990 and 2001

PubMed Central

2005-01-01

Abstract Passive laboratory-based surveillance data from Alberta Agriculture Food and Rural Development were analyzed for common Salmonella serovars, prevalences, trends, and for the presence of temporal clusters. There were 1767 isolates between October 1990 and December 2001 comprising 63 different serovars, including 961 isolates from chickens, 418 from cattle, 108 from pigs, 102 from turkeys, and 178 from all other species combined. Salmonella Typhimurium, Heidelberg, Hadar, Kentucky, and Thompson were the 5 most frequently isolated serovars. Approximately 60% of the S. Typhimurium were isolated from cattle, whereas over 90% of the S. Heidelberg, Hadar, Kentucky, and Thompson were isolated from chickens. Salmonella Enteritidis was rarely isolated. There was an increasing trend in isolates from chickens, cattle, and pigs, and a decreasing trend in isolates from turkeys. Temporal clusters were observed in 11 of 15 serovars examined in chickens (S. Anatum, Heidelberg, Infantis, Kentucky, Mbandaka, Montevideo, Nienstedten, Oranienburg, Thompson, Typhimurium, and Typhimurium var. Copenhagen), 5 of 5 serovars in cattle (S. Dublin, Montevideo, Muenster, Typhimurium, and Typhimurium var. Copenhagen), and 1 of 3 serovars in pigs (S. Typhimurium). Short-duration clusters may imply point source infections, whereas long-duration clusters may indicate an increase in the prevalence of the serovar, farm-to-farm transmission, or a wide-spread common source. A higher concentration of clusters in the winter months may reflect greater confinement, reduced ventilation, stressors, or increased exposure to wildlife vectors that are sharing housing during the winter. Detection of large clusters of Salmonella may have public health implications in addition to animal health concerns. PMID:15971672

Molecular epidemiological characteristics of Salmonella enterica serovars Enteritidis, Typhimurium and Livingstone strains isolated in a Tunisian university hospital.

PubMed

Ktari, Sonia; Ksibi, Boutheina; Gharsallah, Houda; Mnif, Basma; Maalej, Sonda; Rhimi, Fouzia; Hammami, Adnene

2016-03-01

Enteritidis, Typhimurium and Livingstone are the main Salmonella enterica serovars recovered in Tunisia. Here, we aimed to assess the genetic diversity of fifty-seven Salmonella enterica strains from different sampling periods, origins and settings using pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST) and multi-locus variable-number tandem repeat analysis (MLVA). Salmonella Enteritidis, isolated from human and food sources from two regions in Sfax in 2007, were grouped into one cluster using PFGE. However, using MLVA these strains were divided into two clusters. Salmonella Typhimurium strains, recovered in 2012 and represent sporadic cases of human clinical isolates, were included in one PFGE cluster. Nevertheless, the MLVA technique, divided Salmonella Typhimurium isolates into six clusters with diversity index reaching (DI = 0.757). For Salmonella Livingstone which was responsible of two nosocomial outbreaks during 2000-2003, the PFGE and MLVA methods showed that these strains were genetically closely related. Salmonella Enteritidis and Salmonella Livingstone populations showed a single ST lineage ST11 and ST543 respectively. For Salmonella Typhimurium, two MLST sequence types ST19 and ST328 were defined. Salmonella Enteritidis and Salmonella Typhimurium strains were clearly differentiated by MLVA which was not the case using PFGE. © 2015 APMIS. Published by John Wiley & Sons Ltd.

Spatial distribution of antibodies to Salmonella enterica serovar Typhimurium O antigens in bulk milk from Texas dairy herds.

PubMed

Graham, S L; Barling, K S; Waghela, S; Scott, H M; Thompson, J A

2005-06-10

Environmental factors that enhance either the survivability or dispersion of Salmonella enterica serovar Typhimurium (S. Typhimurium) could result in a spatial pattern of disease risk. The objectives of this study were to: (1) describe herd status based on antibody response to Salmonella Typhimurium as estimated from bulk tank milk samples and (2) to describe the resulting geographical patterns found among Texas dairy herds. Eight hundred and fifty-two bulk milk samples were collected from georeferenced dairy farms and assayed by an indirect enzyme-linked immunosorbent assay (ELISA) using S. Typhimurium lipopolysaccharide (LPS). ELISA signal-to-noise ratios for each bulk tank milk sample were calculated and used for geostatistical analyses. Best-fit parameters for the exponential theoretical variogram included a range of 438.8 km, partial sill of 0.060 and nugget of 0.106. The partial sill is the classical geostatistical term for the variance that can be explained by the herd's location and the nugget is the spatially random component of the variance. We have identified a spatial process in bulk milk tank titers for S. Typhimurium in Texas dairy herds and present a map of the expected smoothed surface. Areas with higher expected titers should be targeted in further studies on controlling Salmonella infection with environmental modifications.

Colonization of internal organs by Salmonella serovars Heidelberg and Typhimurium in experimentally infected laying hens housed in enriched colony cages at different stocking densities

USDA-ARS?s Scientific Manuscript database

Contaminated eggs produced by infected commercial laying flocks are often implicated as sources of human infections with Salmonella Enteritidis, but Salmonella serovars Heidelberg and Typhimurium have also been significantly associated with egg-transmitted illness. Contamination of the edible conten...

Iron-Induced Virulence of Salmonella enterica Serovar Typhimurium at the Intestinal Epithelial Interface Can Be Suppressed by Carvacrol

PubMed Central

Kortman, Guus A. M.; Roelofs, Rian W. H. M.; Swinkels, Dorine W.; de Jonge, Marien I.; Burt, Sara A.

2014-01-01

Oral iron therapy can increase the abundance of bacterial pathogens, e.g., Salmonella spp., in the large intestine of African children. Carvacrol is a natural compound with antimicrobial activity against various intestinal bacterial pathogens, among which is the highly prevalent Salmonella enterica serovar Typhimurium. This study aimed to explore a presumed interaction between carvacrol and bacterial iron handling and to assess the potential of carvacrol in preventing the increase of bacterial pathogenicity during high iron availability. S. Typhimurium was cultured with increasing concentrations of iron and carvacrol to study the effects of these combined interventions on growth, adhesion to intestinal epithelial cells, and iron uptake/influx in both bacterial and epithelial cells. In addition, the ability of carvacrol to remove iron from the high-affinity ligand transferrin and an Fe-dye complex was examined. Carvacrol retarded growth of S. Typhimurium at all iron conditions. Furthermore, iron-induced epithelial adhesion was effectively reduced by carvacrol at high iron concentrations. The reduction of growth and virulence by carvacrol was not paralleled by a change in iron uptake or influx into S. Typhimurium. In contrast, bioavailability of iron for epithelial cells was moderately decreased under these conditions. Further, carvacrol was shown to lack the properties of an iron binding molecule; however, it was able to weaken iron-ligand interactions by which it may possibly interfere with bacterial virulence. In conclusion, our in vitro data suggest that carvacrol has the potential to serve as a novel dietary supplement to prevent pathogenic overgrowth and colonization in the large intestine during oral iron therapy. PMID:24379194

Colonization of internal organs by Salmonella serovars Heidelberg and Typhimurium in experimentally infected laying hens housed in enriched colony cages at different stocking densities

USDA-ARS?s Scientific Manuscript database

Contaminated eggs produced by infected commercial laying flocks are often implicated as sources of human infections with Salmonella Enteritidis, but Salmonella serovars Heidelberg and Typhimurium have also been associated with egg-transmitted illness. Contamination of the edible contents of eggs is ...

The Rcs-Regulated Colanic Acid Capsule Maintains Membrane Potential in Salmonella enterica serovar Typhimurium

PubMed Central

Pando, Jasmine M.; Karlinsey, Joyce E.; Lara, Jimmie C.; Libby, Stephen J.

2017-01-01

ABSTRACT The Rcs phosphorelay and Psp (phage shock protein) systems are envelope stress responses that are highly conserved in gammaproteobacteria. The Rcs regulon was found to be strongly induced during metal deprivation of Salmonella enterica serovar Typhimurium lacking the Psp response. Nineteen genes activated by the RcsA-RcsB response regulator make up an operon responsible for the production of colanic acid capsular polysaccharide, which promotes biofilm development. Despite more than half a century of research, the physiological function of colanic acid has remained elusive. Here we show that Rcs-dependent colanic acid production maintains the transmembrane electrical potential and proton motive force in cooperation with the Psp response. Production of negatively charged exopolysaccharide covalently bound to the outer membrane may enhance the surface potential by increasing the local proton concentration. This provides a unifying mechanism to account for diverse Rcs/colanic acid-related phenotypes, including susceptibility to membrane-damaging agents and biofilm formation. PMID:28588134

Analysis of antimicrobial resistance genes detected in multidrug-resistant Salmonella enterica serovar Typhimurium isolated from food animals.

PubMed

Glenn, LaShanda M; Lindsey, Rebecca L; Frank, Joseph F; Meinersmann, Richard J; Englen, Mark D; Fedorka-Cray, Paula J; Frye, Jonathan G

2011-09-01

Multidrug-resistant (MDR) Salmonella enterica serovar Typhimurium is the most prevalent penta-resistant serovar isolated from animals by the U.S. National Antimicrobial Resistance Monitoring System. Penta-resistant isolates are often resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline. To investigate MDR in Salmonella Typhimurium (including variant 5-), one isolate each from cattle, poultry, and swine with at least the ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline phenotype were selected for each year from 1997 to 2007 (n = 33) for microarray analysis of antimicrobial resistance, incompatibility IncA/C, and HI1 plasmid genes. Cluster analysis based on these data separated 31 of the isolates into two groups A and B (15 and 16 isolates, respectively). Isolates in group A were phage type DT104 or U302 and were mostly swine isolates (7/15). Genes detected included intI1, bla(PSE-1), floR, aadA, sulI, tet(G), and tetR, which are often found in Salmonella Genomic Island I. Isolates in group B had numerous IncA/C plasmid genes detected and were mostly cattle isolates (9/16). Genes detected included bla(CMY-2), floR, aac(3), aadA, aphA1, strA, strB, sulI, sulII, dfrA, dhf, tet(A)(B)(C)(D), and tetR, which are often found on MDR-AmpC IncA/C plasmids. The IncA/C replicon was also detected in all group B isolates. The two remaining isolates did not cluster with any others and both had many HI1 plasmid genes detected. Linkage disequilibrium analysis detected significant associations between plasmid replicon type, phage type, and animal source. These data suggest that MDR in Salmonella Typhimurium is associated with DT104/Salmonella Genomic Island I or IncA/C MDR-AmpC encoding plasmids and these genetic elements have persisted throughout the study period.

Molecular Epidemiology of Salmonella enterica Serovar Typhimurium Isolates Determined by Pulsed-Field Gel Electrophoresis: Comparison of Isolates from Avian Wildlife, Domestic Animals, and the Environment in Norway

PubMed Central

Refsum, Thorbjørn; Heir, Even; Kapperud, Georg; Vardund, Traute; Holstad, Gudmund

2002-01-01

The molecular epidemiology of 142 isolates of Salmonella enterica serovar Typhimurium from avian wildlife, domestic animals, and the environment in Norway was investigated using pulsed-field gel electrophoresis (PFGE) and computerized numerical analysis of the data. The bacterial isolates comprised 79 isolates from wild-living birds, including 46 small passerines and 26 gulls, and 63 isolates of nonavian origin, including 50 domestic animals and 13 environmental samples. Thirteen main clusters were discernible at the 90% similarity level. Most of the isolates (83%) were grouped into three main clusters. These were further divided into 20 subclusters at the 95% similarity level. Isolates from passerines, gulls, and pigeons dominated within five subclusters, whereas isolates from domestic animals and the environment belonged to many different subclusters with no predominance. The results support earlier results that passerines constitute an important source of infection to humans in Norway, whereas it is suggested that gulls and pigeons, based on PFGE analysis, represent only a minor source of human serovar Typhimurium infections. Passerines, gulls, and pigeons may also constitute a source of infection of domestic animals and feed plants or vice versa. Three isolates from cattle and a grain source, of which two were multiresistant, were confirmed as serovar Typhimurium phage type DT 104. These represent the first reported phage type DT 104 isolates from other sources than humans in Norway. PMID:12406755

Development of a Novel, Rapid Multiplex Polymerase Chain Reaction Assay for the Detection and Differentiation of Salmonella enterica Serovars Enteritidis and Typhimurium Using Ultra-Fast Convection Polymerase Chain Reaction.

PubMed

Kim, Tae-Hoon; Hwang, Hyun Jin; Kim, Jeong Hee

2017-10-01

Salmonella enterica serovars Enteritidis and Typhimurium are the most common causative agents of human nontyphoidal salmonellosis. The rapid detection and timely treatment of salmonellosis are important to increase the curative ratio and prevent spreading of the disease. In this study, we developed a rapid multiplex convection polymerase chain reaction (PCR) method to detect Salmonella spp. and differentiate Salmonella Enteritidis and Salmonella Typhimurium. We used the invA gene for Salmonella spp. detection. Salmonella Enteritidis-specific primers and Salmonella Typhimurium-specific primers were designed using the insertion element (IE) and spy genes, respectively. The primer set for Salmonella spp. detection clearly detected both Salmonella Enteritidis and Salmonella Typhimurium after a 21-min amplification reaction. Serovar-specific primer sets for Salmonella Enteritidis and Salmonella Typhimurium specifically detected each target species in a 21-min amplification reaction. We were able to detect Salmonella spp. at a single copy level in the singleplex mode. The limits of detection for Salmonella Enteritidis and Salmonella Typhimurium were 30 copies in both the singleplex and multiplex modes. The PCR run time could be reduced to 10.5 min/15 cycles. The multiplex convection PCR method developed in this study could detect the Salmonella spp. Salmonella Enteritidis and Salmonella Typhimurium in artificially contaminated milk with as few as 10 0 colony-forming unit/mL after 4-h enrichment. The PCR assay developed in this study provides a rapid, specific, and sensitive method for the detection of Salmonella spp. and the differentiation of Salmonella Enteritidis and Salmonella Typhimurium.

Salmonella enterica serovar-specific transcriptional reprogramming of infected cells.

PubMed

Hannemann, Sebastian; Galán, Jorge E

2017-07-01

Despite their high degree of genomic similarity, different Salmonella enterica serovars are often associated with very different clinical presentations. In humans, for example, the typhoidal S. enterica serovar Typhi causes typhoid fever, a life-threatening systemic disease. In contrast, the non-typhoidal S. enterica serovar Typhimurium causes self-limiting gastroenteritis. The molecular bases for these different clinical presentations are incompletely understood. The ability to re-program gene expression in host cells is an essential virulence factor for typhoidal and non-typhoidal S. enterica serovars. Here, we have compared the transcriptional profile of cultured epithelial cells infected with S. Typhimurium or S. Typhi. We found that both serovars stimulated distinct transcriptional responses in infected cells that are associated with the stimulation of specific signal transduction pathways. These specific responses were associated with the presence of a distinct repertoire of type III secretion effector proteins. These observations provide major insight into the molecular bases for potential differences in the pathogenic mechanisms of typhoidal and non-typhoidal S. enterica serovars.

Role of outer membrane lipopolysaccharides in the protection of Salmonella enterica serovar Typhimurium from desiccation damage.

PubMed

Garmiri, Penelope; Coles, Karen E; Humphrey, Tom J; Cogan, Tristan A

2008-04-01

The ability to survive desiccation between hosts is often essential to the success of pathogenic bacteria. The bacterial outer membrane is both the cellular interface with hostile environments and the focus of much of the drying-induced damage. This study examined the contribution of outer membrane-associated polysaccharides to the survival of Salmonella enterica serovar Typhimurium in air-dried blood droplets following growth in high and low osmolarity medium and under conditions known to induce expression of these polysaccharides. Strains lacking the O polysaccharide (OPS) element of the outer membrane lipopolysaccharide were more sensitive to desiccation. Lipopolysaccharide core mutation further to OPS loss did not result in increased susceptibility to drying. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed lipopolysaccharide profiles that supported the hypothesis that OPS expression is required for optimal drying resistance in S. Typhimurium. The role of O antigen in Salmonella spp. in maintaining a hydrated layer around the dried cell or in slowing the rate of dehydration and rehydration is discussed.

Novel Approach of a Phage-Based Magnetoelastic Biosensor for the Detection of Salmonella enterica serovar Typhimurium in Soil.

PubMed

Park, Mi-Kyung; Chin, Bryan A

2016-12-28

To date, there has been no employment of a magnetoelastic (ME) biosensor method to detect Salmonella enterica serovar Typhimurium in soil. The ME biosensor method needs to be investigated and modified for its successful performance. The filtration method, cation-exchange resin method, and combinations of both methods were employed for the extraction of S . Typhimurium from soil. The number of S . Typhimurium and the resonant frequency shift of the ME sensor were then compared using a brilliant green sulfa agar plate and an HP 8751A network analyzer. A blocking study was performed using bovine serum albumin (BSA), polyethylene glycol (PEG), and casein powder suspension. Finally, the modified ME biosensor method was performed to detect S . Typhimurium in soil. The number of S . Typhimurium was significantly decreased from 7.10 log CFU/soil to 4.45-4.72 log CFU/soil after introduction of the cation-exchange resin method. The greatest resonant frequency shift of the measurement sensor was found when employing centrifugation and filtration procedures. The resonant frequency shift of the PEG-blocked measurement sensor was 3,219 ± 755 Hz, which was significantly greater than those of the BSA- and casein-blocked ME sensor. The optimum concentration of PEG was determined to be 1.0 mg/ml after considering the resonant shift and economic issue. Finally, the modified ME biosensor method was able to detect S . Typhimurium in soil in a dose-response manner. Although these modifications of the ME biosensor method sacrificed some advantages, such as cost, time effectiveness, and operator friendliness, this study demonstrated a novel approach of the ME biosensor method to detect S . Typhimurium in soil.

Infection of Mice by Salmonella enterica Serovar Enteritidis Involves Additional Genes That Are Absent in the Genome of Serovar Typhimurium

PubMed Central

Silva, Cecilia A.; Blondel, Carlos J.; Quezada, Carolina P.; Porwollik, Steffen; Andrews-Polymenis, Helene L.; Toro, Cecilia S.; Zaldívar, Mercedes; Contreras, Inés

2012-01-01

Salmonella enterica serovar Enteritidis causes a systemic, typhoid-like infection in newly hatched poultry and mice. In the present study, a library of 54,000 transposon mutants of S. Enteritidis phage type 4 (PT4) strain P125109 was screened for mutants deficient in the in vivo colonization of the BALB/c mouse model using a microarray-based negative-selection screening. Mutants in genes known to contribute to systemic infection (e.g., Salmonella pathogenicity island 2 [SPI-2], aro, rfa, rfb, phoP, and phoQ) and enteric infection (e.g., SPI-1 and SPI-5) in this and other Salmonella serovars displayed colonization defects in our assay. In addition, a strong attenuation was observed for mutants in genes and genomic islands that are not present in S. Typhimurium or in most other Salmonella serovars. These genes include a type I restriction/modification system (SEN4290 to SEN4292), the peg fimbrial operon (SEN2144A to SEN2145B), a putative pathogenicity island (SEN1970 to SEN1999), and a type VI secretion system remnant SEN1001, encoding a hypothetical protein containing a lysin motif (LysM) domain associated with peptidoglycan binding. Proliferation defects for mutants in these individual genes and in exemplar genes for each of these clusters were confirmed in competitive infections with wild-type S. Enteritidis. A ΔSEN1001 mutant was defective for survival within RAW264.7 murine macrophages in vitro. Complementation assays directly linked the SEN1001 gene to phenotypes observed in vivo and in vitro. The genes identified here may perform novel virulence functions not characterized in previous Salmonella models. PMID:22083712

Bistable Expression of CsgD in Salmonella enterica Serovar Typhimurium Connects Virulence to Persistence

PubMed Central

MacKenzie, Keith D.; Wang, Yejun; Shivak, Dylan J.; Wong, Cynthia S.; Hoffman, Leia J. L.; Lam, Shirley; Kröger, Carsten; Cameron, Andrew D. S.; Townsend, Hugh G. G.; Köster, Wolfgang

2015-01-01

Pathogenic bacteria often need to survive in the host and the environment, and it is not well understood how cells transition between these equally challenging situations. For the human and animal pathogen Salmonella enterica serovar Typhimurium, biofilm formation is correlated with persistence outside a host, but the connection to virulence is unknown. In this study, we analyzed multicellular-aggregate and planktonic-cell subpopulations that coexist when S. Typhimurium is grown under biofilm-inducing conditions. These cell types arise due to bistable expression of CsgD, the central biofilm regulator. Despite being exposed to the same stresses, the two cell subpopulations had 1,856 genes that were differentially expressed, as determined by transcriptome sequencing (RNA-seq). Aggregated cells displayed the characteristic gene expression of biofilms, whereas planktonic cells had enhanced expression of numerous virulence genes. Increased type three secretion synthesis in planktonic cells correlated with enhanced invasion of a human intestinal cell line and significantly increased virulence in mice compared to the aggregates. However, when the same groups of cells were exposed to desiccation, the aggregates survived better, and the competitive advantage of planktonic cells was lost. We hypothesize that CsgD-based differentiation is a form of bet hedging, with single cells primed for host cell invasion and aggregated cells adapted for persistence in the environment. This allows S. Typhimurium to spread the risks of transmission and ensures a smooth transition between the host and the environment. PMID:25824832

Complete Genome Sequencing of a Multidrug-Resistant and Human-Invasive Salmonella enterica Serovar Typhimurium Strain of the Emerging Sequence Type 213 Genotype

PubMed Central

Calva, Edmundo; Zaidi, Mussaret B.; Sanchez-Flores, Alejandro; Estrada, Karel; Silva, Genivaldo G. Z.; Soto-Jiménez, Luz M.; Wiesner, Magdalena; Fernández-Mora, Marcos; Edwards, Robert A.

2015-01-01

Salmonella enterica subsp. enterica serovar Typhimurium strain YU39 was isolated in 2005 in the state of Yucatán, Mexico, from a human systemic infection. The YU39 strain is representative of the multidrug-resistant emergent sequence type 213 (ST213) genotype. The YU39 complete genome is composed of a chromosome and seven plasmids. PMID:26089426

Complete genome sequencing of a multidrug-resistant and human-invasive Salmonella enterica serovar Typhimurium strain of the emerging sequence type 213 genotype

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calva, Edmundo; Silva, Claudia; Zaidi, Mussaret B.

Salmonella enterica subsp. enterica serovar Typhimurium strain YU39 was isolated in 2005 in the state of Yucatán, Mexico, from a human systemic infection. The YU39 strain is representative of the multidrug-resistant emergent sequence type 213 (ST213) genotype. The YU39 complete genome is composed of a chromosome and seven plasmids.

Complete genome sequencing of a multidrug-resistant and human-invasive Salmonella enterica serovar Typhimurium strain of the emerging sequence type 213 genotype

DOE PAGES

Calva, Edmundo; Silva, Claudia; Zaidi, Mussaret B.; ...

2015-06-18

Salmonella enterica subsp. enterica serovar Typhimurium strain YU39 was isolated in 2005 in the state of Yucatán, Mexico, from a human systemic infection. The YU39 strain is representative of the multidrug-resistant emergent sequence type 213 (ST213) genotype. The YU39 complete genome is composed of a chromosome and seven plasmids.

Zinc Supplementation, via GPR39, Upregulates PKCζ to Protect Intestinal Barrier Integrity in Caco-2 Cells Challenged by Salmonella enterica Serovar Typhimurium.

PubMed

Shao, Yu-Xin; Lei, Zhao; Wolf, Patricia G; Gao, Yan; Guo, Yu-Ming; Zhang, Bing-Kun

2017-07-01

Background: Zinc has been shown to improve intestinal barrier function against Salmonella enterica serovar Typhimurium ( S. typhimurium ) infection, but the mechanisms involved in this process remain undefined. Objective: We aimed to explore the roles of G protein-coupled receptor (GPR)39 and protein kinase Cζ (PKCζ) in the regulation by zinc of intestinal barrier function. Methods: A Transwell Caco-2 monolayer was pretreated with 0, 50, or 100 μM Zn and then incubated with S. typhimurium for 0-6 h. Afterward, cells silenced by the small interfering RNA for GPR39 or PKCζ were pretreated with 100 μM Zn and incubated with S. typhimurium for 3 h. Finally, transepithelial electrical resistance (TEER), permeability, tight junction (TJ) proteins, and signaling molecules GPR39 and PKCζ were measured. Results: Compared with controls, S. typhimurium decreased TEER by 62.3-96.2% at 4-6 h ( P < 0.001), increased ( P < 0.001) permeability at 6 h, and downregulated ( P < 0.05) TJ protein zonula occludens (ZO)-1 and occludin by 104-123%, as well as Toll-like receptor 2 and PKCζ by 35.1% and 75.2%, respectively. Compared with S. typhimurium- challenged cells, 50 and 100 μM Zn improved TEER by 26.3-60.9% at 4-6 h ( P < 0.001) and decreased ( P < 0.001) permeability and bacterial invasion at 6 h. A total of 100 μM Zn increased ZO-1, occludin, GPR39, and PKCζ 0.72- to 1.34-fold ( P < 0.05); however, 50 μM Zn did not affect ZO-1 or occludin ( P > 0.1). Silencing GPR39 decreased ( P < 0.05) zinc-activated PKCζ and blocked ( P < 0.05) the promotion of zinc on epithelial integrity. Furthermore, silencing PKCζ counteracted the protective effect of zinc on epithelial integrity but did not inhibit GPR39 ( P = 0.138). Conclusion: We demonstrated that zinc upregulates PKCζ by activating GPR39 to enhance the abundance of ZO-1, thereby improving epithelial integrity in S. typhimurium- infected Caco-2 cells. © 2017 American Society for Nutrition.

Salmonella DIVA vaccine reduces disease, colonization and shedding due to virulent S. Typhimurium infection in swine

USDA-ARS?s Scientific Manuscript database

Non-host adapted Salmonella serovars are opportunistic pathogens that can colonize food-producing animals without causing overt disease, including the frequent foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium). Interventions against Salmonella need to both enhance food safe...

Replication of Salmonella enterica Serovar Typhimurium in Human Monocyte-Derived Macrophages

PubMed Central

Lathrop, Stephanie K.; Binder, Kelsey A.; Starr, Tregei; Cooper, Kendal G.; Chong, Audrey; Carmody, Aaron B.

2015-01-01

Salmonella enterica serovar Typhimurium is a common cause of food-borne gastrointestinal illness, but additionally it causes potentially fatal bacteremia in some immunocompromised patients. In mice, systemic spread and replication of the bacteria depend upon infection of and replication within macrophages, but replication in human macrophages is not widely reported or well studied. In order to assess the ability of Salmonella Typhimurium to replicate in human macrophages, we infected primary monocyte-derived macrophages (MDM) that had been differentiated under conditions known to generate different phenotypes. We found that replication in MDM depends greatly upon the phenotype of the cells, as M1-skewed macrophages did not allow replication, while M2a macrophages and macrophages differentiated with macrophage colony-stimulating factor (M-CSF) alone (termed M0) did. We describe how additional conditions that alter the macrophage phenotype or the gene expression of the bacteria affect the outcome of infection. In M0 MDM, the temporal expression of representative genes from Salmonella pathogenicity islands 1 and 2 (SPI1 and SPI2) and the importance of the PhoP/Q two-component regulatory system are similar to what has been shown in mouse macrophages. However, in contrast to mouse macrophages, where replication is SPI2 dependent, we observed early SPI2-independent replication in addition to later SPI2-dependent replication in M0 macrophages. Only SPI2-dependent replication was associated with death of the host cell at later time points. Altogether, our results reveal a very nuanced interaction between Salmonella and human macrophages. PMID:25895967

Investigation of Outbreaks of Salmonella enterica Serovar Typhimurium and Its Monophasic Variants Using Whole-Genome Sequencing, Denmark

PubMed Central

Gymoese, Pernille; Sørensen, Gitte; Litrup, Eva; Olsen, John Elmerdal; Nielsen, Eva Møller

2017-01-01

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 genetic clone of monophasic variants (ST34). PMID:28930002

Salmonella enterica serovar Typhimurium adhesion and cytotoxicity during epithelial cell stress is reduced by Lactobacillus rhamnosus GG

PubMed Central

Burkholder, Kristin M; Bhunia, Arun K

2009-01-01

Background Physiological stressors may alter susceptibility of the host intestinal epithelium to infection by enteric pathogens. In the current study, cytotoxic effect, adhesion and invasion of Salmonella enterica serovar Typhimurium (S. Typhimurium) to Caco-2 cells exposed to thermal stress (41°C, 1 h) was investigated. Probiotic bacteria have been shown to reduce interaction of pathogens with the epithelium under non-stress conditions and may have a significant effect on epithelial viability during infection; however, probiotic effect on pathogen interaction with epithelial cells under physiological stress is not known. Therefore, we investigated the influence of Lactobacillus rhamnosus GG and Lactobacillus gasseri on Salmonella adhesion and Salmonella-induced cytotoxicity of Caco-2 cells subjected to thermal stress. Results Thermal stress increased the cytotoxic effect of both S. Typhimurium (P = 0.0001) and nonpathogenic E. coli K12 (P = 0.004) to Caco-2 cells, and resulted in greater susceptibility of cell monolayers to S. Typhimurium adhesion (P = 0.001). Thermal stress had no significant impact on inflammatory cytokines released by Caco-2 cells, although exposure to S. Typhimurium resulted in greater than 80% increase in production of IL-6 and IL-8. Blocking S. Typhimurium with anti-ShdA antibody prior to exposure of Salmonella decreased adhesion (P = 0.01) to non-stressed and thermal-stressed Caco-2 cells. Pre-exposure of Caco-2 cells to L. rhamnosus GG significantly reduced Salmonella-induced cytotoxicity (P = 0.001) and Salmonella adhesion (P = 0.001) to Caco-2 cells during thermal stress, while L. gasseri had no effect. Conclusion Results suggest that thermal stress increases susceptibility of intestinal epithelial Caco-2 cells to Salmonella adhesion, and increases the cytotoxic effect of Salmonella during infection. Use of L. rhamnosus GG as a probiotic may reduce the severity of infection during epithelial cell stress. Mechanisms by which thermal

Differences in Pathogenesis for Salmonella enterica serovar Typhimurium in the Mouse Versus the Swine Model Identify Bacterial Gene Products Required for Systemic but not Gastrointestinal Disease

USDA-ARS?s Scientific Manuscript database

Over the last several decades, the mouse model of Typhoid fever has been an extremely productive model to investigate Salmonella enterica serovar Typhimurium pathogenesis. The mouse is the paradigm for investigating systemic disease due to infection by Salmonella; however, the swine model of gastro...

Synthesis of Metallo-β-Lactamase VIM-2 Is Associated with a Fitness Reduction in Salmonella enterica Serovar Typhimurium

PubMed Central

Cordeiro, Nicolás F.; Chabalgoity, José A.; Yim, Lucía

2014-01-01

Antibiotic resistance, especially due to β-lactamases, has become one of the main obstacles in the correct treatment of Salmonella infections; furthermore, antibiotic resistance determines a gain of function that may encompass a biological cost, or fitness reduction, to the resistant bacteria. The aim of this work was to determine in vitro if the production of the class B β-lactamase VIM-2 determined a fitness cost for Salmonella enterica serovar Typhimurium. To that end the gene blaVIM-2 was cloned into the virulent strain S. Typhimurium SL1344, using both the tightly regulated pBAD22 vector and the natural plasmid pST12, for inducible and constitutive expression, respectively. Fitness studies were performed by means of motility, growth rate, invasiveness in epithelial cells, and plasmid stability. The expression of blaVIM-2 was accompanied by alterations in micro- and macroscopic morphology and reduced growth rate and motility, as well as diminished invasiveness in epithelial cells. These results suggest that VIM-2 production entails a substantial fitness cost for S. Typhimurium, which in turn may account for the extremely low number of reports of metallo-β-lactamase-producing Salmonella spp. PMID:25136026

Global Genomic Epidemiology of Salmonella enterica Serovar Typhimurium DT104

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leekitcharoenphon, Pimlapas; Hendriksen, Rene S.; Le Hello, Simon

It has been 30 years since the initial emergence and subsequent rapid global spread of multidrug-resistant Salmonella enterica serovar Typhimurium DT104 (MDR DT104). Nonetheless, its origin and transmission route have never been revealed. In this paper, we used whole-genome sequencing (WGS) and temporally structured sequence analysis within a Bayesian framework to reconstruct temporal and spatial phylogenetic trees and estimate the rates of mutation and divergence times of 315 S. Typhimurium DT104 isolates sampled from 1969 to 2012 from 21 countries on six continents. DT104 was estimated to have emerged initially as antimicrobial susceptible in ~1948 (95% credible interval [CI], 1934more » to 1962) and later became MDR DT104 in ~1972 (95% CI, 1972 to 1988) through horizontal transfer of the 13-kb Salmonella genomic island 1 (SGI1) MDR region into susceptible strains already containing SGI1. This was followed by multiple transmission events, initially from central Europe and later between several European countries. An independent transmission to the United States and another to Japan occurred, and from there MDR DT104 was probably transmitted to Taiwan and Canada. An independent acquisition of resistance genes took place in Thailand in ~1975 (95% CI, 1975 to 1990). In Denmark, WGS analysis provided evidence for transmission of the organism between herds of animals. Interestingly, the demographic history of Danish MDR DT104 provided evidence for the success of the program to eradicate Salmonella from pig herds in Denmark from 1996 to 2000. Finally, the results from this study refute several hypotheses on the evolution of DT104 and suggest that WGS may be useful in monitoring emerging clones and devising strategies for prevention of Salmonella infections.« less

Global Genomic Epidemiology of Salmonella enterica Serovar Typhimurium DT104

PubMed Central

Hendriksen, Rene S.; Le Hello, Simon; Weill, François-Xavier; Baggesen, Dorte Lau; Jun, Se-Ran; Lund, Ole; Crook, Derrick W.; Wilson, Daniel J.; Aarestrup, Frank M.

2016-01-01

It has been 30 years since the initial emergence and subsequent rapid global spread of multidrug-resistant Salmonella enterica serovar Typhimurium DT104 (MDR DT104). Nonetheless, its origin and transmission route have never been revealed. We used whole-genome sequencing (WGS) and temporally structured sequence analysis within a Bayesian framework to reconstruct temporal and spatial phylogenetic trees and estimate the rates of mutation and divergence times of 315 S. Typhimurium DT104 isolates sampled from 1969 to 2012 from 21 countries on six continents. DT104 was estimated to have emerged initially as antimicrobial susceptible in ∼1948 (95% credible interval [CI], 1934 to 1962) and later became MDR DT104 in ∼1972 (95% CI, 1972 to 1988) through horizontal transfer of the 13-kb Salmonella genomic island 1 (SGI1) MDR region into susceptible strains already containing SGI1. This was followed by multiple transmission events, initially from central Europe and later between several European countries. An independent transmission to the United States and another to Japan occurred, and from there MDR DT104 was probably transmitted to Taiwan and Canada. An independent acquisition of resistance genes took place in Thailand in ∼1975 (95% CI, 1975 to 1990). In Denmark, WGS analysis provided evidence for transmission of the organism between herds of animals. Interestingly, the demographic history of Danish MDR DT104 provided evidence for the success of the program to eradicate Salmonella from pig herds in Denmark from 1996 to 2000. The results from this study refute several hypotheses on the evolution of DT104 and suggest that WGS may be useful in monitoring emerging clones and devising strategies for prevention of Salmonella infections. PMID:26944846

Global Genomic Epidemiology of Salmonella enterica Serovar Typhimurium DT104

DOE PAGES

Leekitcharoenphon, Pimlapas; Hendriksen, Rene S.; Le Hello, Simon; ...

2016-03-04

It has been 30 years since the initial emergence and subsequent rapid global spread of multidrug-resistant Salmonella enterica serovar Typhimurium DT104 (MDR DT104). Nonetheless, its origin and transmission route have never been revealed. In this paper, we used whole-genome sequencing (WGS) and temporally structured sequence analysis within a Bayesian framework to reconstruct temporal and spatial phylogenetic trees and estimate the rates of mutation and divergence times of 315 S. Typhimurium DT104 isolates sampled from 1969 to 2012 from 21 countries on six continents. DT104 was estimated to have emerged initially as antimicrobial susceptible in ~1948 (95% credible interval [CI], 1934more » to 1962) and later became MDR DT104 in ~1972 (95% CI, 1972 to 1988) through horizontal transfer of the 13-kb Salmonella genomic island 1 (SGI1) MDR region into susceptible strains already containing SGI1. This was followed by multiple transmission events, initially from central Europe and later between several European countries. An independent transmission to the United States and another to Japan occurred, and from there MDR DT104 was probably transmitted to Taiwan and Canada. An independent acquisition of resistance genes took place in Thailand in ~1975 (95% CI, 1975 to 1990). In Denmark, WGS analysis provided evidence for transmission of the organism between herds of animals. Interestingly, the demographic history of Danish MDR DT104 provided evidence for the success of the program to eradicate Salmonella from pig herds in Denmark from 1996 to 2000. Finally, the results from this study refute several hypotheses on the evolution of DT104 and suggest that WGS may be useful in monitoring emerging clones and devising strategies for prevention of Salmonella infections.« less

wksl3, a New Biocontrol Agent for Salmonella enterica Serovars Enteritidis and Typhimurium in Foods: Characterization, Application, Sequence Analysis, and Oral Acute Toxicity Study

PubMed Central

Kang, Hyun-Wol; Kim, Jae-Won; Jung, Tae-Sung

2013-01-01

Of the Salmonella enterica serovars, S. Enteritidis and S. Typhimurium are responsible for most of the Salmonella outbreaks implicated in the consumption of contaminated foods in the Republic of Korea. Because of the widespread occurrence of antimicrobial-resistant Salmonella in foods and food processing environments, bacteriophages have recently surfaced as an alternative biocontrol tool. In this study, we isolated a virulent bacteriophage (wksl3) that could specifically infect S. Enteritidis, S. Typhimurium, and several additional serovars. Transmission electron microscopy revealed that phage wksl3 belongs to the family Siphoviridae. Complete genome sequence analysis and bioinformatic analysis revealed that the DNA of phage wksl3 is composed of 42,766 bp with 64 open reading frames. Since it does not encode any phage lysogeny factors, toxins, pathogen-related genes, or food-borne allergens, phage wksl3 may be considered a virulent phage with no side effects. Analysis of genetic similarities between phage wksl3 and four of its relatives (SS3e, vB_SenS-Ent1, SE2, and SETP3) allowed wksl3 to be categorized as a SETP3-like phage. A single-dose test of oral toxicity with BALB/c mice resulted in no abnormal clinical observations. Moreover, phage application to chicken skin at 8°C resulted in an about 2.5-log reduction in the number of Salmonella bacteria during the test period. The strong, stable lytic activity, the significant reduction of the number of S. Enteritidis bacteria after application to food, and the lack of clinical symptoms of this phage suggest that wksl3 may be a useful agent for the protection of foods against S. Enteritidis and S. Typhimurium contamination. PMID:23335772

The Legacy of Genetic Analysis Advances Contemporary Research with Escherichia coli K-12 and Salmonella enterica serovar Typhimurium LT2.

PubMed

Stewart, Valley

2017-04-01

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.

Active Suppression of Early Immune Response in Tobacco by the Human Pathogen Salmonella Typhimurium

PubMed Central

Shirron, Natali; Yaron, Sima

2011-01-01

The persistence of enteric pathogens on plants has been studied extensively, mainly due to the potential hazard of human pathogens such as Salmonella enterica being able to invade and survive in/on plants. Factors involved in the interactions between enteric bacteria and plants have been identified and consequently it was hypothesized that plants may be vectors or alternative hosts for enteric pathogens. To survive, endophytic bacteria have to escape the plant immune systems, which function at different levels through the plant-bacteria interactions. To understand how S. enterica survives endophyticaly we conducted a detailed analysis on its ability to elicit or evade the plant immune response. The models of this study were Nicotiana tabacum plants and cells suspension exposed to S. enterica serovar Typhimurium. The plant immune response was analyzed by looking at tissue damage and by testing oxidative burst and pH changes. It was found that S. Typhimurium did not promote disease symptoms in the contaminated plants. Live S. Typhimurium did not trigger the production of an oxidative burst and pH changes by the plant cells, while heat killed or chloramphenicol treated S. Typhimurium and purified LPS of Salmonella were significant elicitors, indicating that S. Typhimurium actively suppress the plant response. By looking at the plant response to mutants defective in virulence factors we showed that the suppression depends on secreted factors. Deletion of invA reduced the ability of S. Typhimurium to suppress oxidative burst and pH changes, indicating that a functional SPI1 TTSS is required for the suppression. This study demonstrates that plant colonization by S. Typhimurium is indeed an active process. S. Typhimurium utilizes adaptive strategies of altering innate plant perception systems to improve its fitness in the plant habitat. All together these results suggest a complex mechanism for perception of S. Typhimurium by plants. PMID:21541320

Microgravity as a novel environmental signal affecting Salmonella enterica serovar Typhimurium virulence

NASA Technical Reports Server (NTRS)

Nickerson, C. A.; Ott, C. M.; Mister, S. J.; Morrow, B. J.; Burns-Keliher, L.; Pierson, D. L.

2000-01-01

The effects of spaceflight on the infectious disease process have only been studied at the level of the host immune response and indicate a blunting of the immune mechanism in humans and animals. Accordingly, it is necessary to assess potential changes in microbial virulence associated with spaceflight which may impact the probability of in-flight infectious disease. In this study, we investigated the effect of altered gravitational vectors on Salmonella virulence in mice. Salmonella enterica serovar Typhimurium grown under modeled microgravity (MMG) were more virulent and were recovered in higher numbers from the murine spleen and liver following oral infection compared to organisms grown under normal gravity. Furthermore, MMG-grown salmonellae were more resistant to acid stress and macrophage killing and exhibited significant differences in protein synthesis than did normal-gravity-grown cells. Our results indicate that the environment created by simulated microgravity represents a novel environmental regulatory factor of Salmonella virulence.

Replication of Salmonella enterica Serovar Typhimurium in Human Monocyte-Derived Macrophages.

PubMed

Lathrop, Stephanie K; Binder, Kelsey A; Starr, Tregei; Cooper, Kendal G; Chong, Audrey; Carmody, Aaron B; Steele-Mortimer, Olivia

2015-07-01

Salmonella enterica serovar Typhimurium is a common cause of food-borne gastrointestinal illness, but additionally it causes potentially fatal bacteremia in some immunocompromised patients. In mice, systemic spread and replication of the bacteria depend upon infection of and replication within macrophages, but replication in human macrophages is not widely reported or well studied. In order to assess the ability of Salmonella Typhimurium to replicate in human macrophages, we infected primary monocyte-derived macrophages (MDM) that had been differentiated under conditions known to generate different phenotypes. We found that replication in MDM depends greatly upon the phenotype of the cells, as M1-skewed macrophages did not allow replication, while M2a macrophages and macrophages differentiated with macrophage colony-stimulating factor (M-CSF) alone (termed M0) did. We describe how additional conditions that alter the macrophage phenotype or the gene expression of the bacteria affect the outcome of infection. In M0 MDM, the temporal expression of representative genes from Salmonella pathogenicity islands 1 and 2 (SPI1 and SPI2) and the importance of the PhoP/Q two-component regulatory system are similar to what has been shown in mouse macrophages. However, in contrast to mouse macrophages, where replication is SPI2 dependent, we observed early SPI2-independent replication in addition to later SPI2-dependent replication in M0 macrophages. Only SPI2-dependent replication was associated with death of the host cell at later time points. Altogether, our results reveal a very nuanced interaction between Salmonella and human macrophages. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The Homolog of the Gene bstA of the BTP1 Phage from Salmonella enterica Serovar Typhimurium ST313 Is an Antivirulence Gene in Salmonella enterica Serovar Dublin.

PubMed

Herrero-Fresno, Ana; Espinel, Irene Cartas; Spiegelhauer, Malene Roed; Guerra, Priscila Regina; Andersen, Karsten Wiber; Olsen, John Elmerdahl

2018-01-01

In a previous study, a novel virulence gene, bstA , identified in a Salmonella enterica serovar Typhimurium sequence type 313 (ST313) strain was found to be conserved in all published Salmonella enterica serovar Dublin genomes. In order to analyze the role of this gene in the host-pathogen interaction in S Dublin, a mutant where this gene was deleted ( S Dublin Δ bstA ) and a mutant which was further genetically complemented with bstA ( S Dublin 3246-C) were constructed and tested in models of in vitro and in vivo infection as well as during growth competition assays in M9 medium, Luria-Bertani broth, and cattle blood. In contrast to the results obtained for a strain of S Typhimurium ST313, the lack of bstA was found to be associated with increased virulence in S Dublin. Thus, S Dublin Δ bstA showed higher levels of uptake than the wild-type strain during infection of mouse and cattle macrophages and higher net replication within human THP-1 cells. Furthermore, during mouse infections, S Dublin Δ bstA was more virulent than the wild type following a single intraperitoneal infection and showed an increased competitive index during competitive infection assays. Deletion of bstA did not affect either the amount of cytokines released by THP-1 macrophages or the cytotoxicity toward these cells. The histology of the livers and spleens of mice infected with the wild-type strain and the S Dublin Δ bstA mutant revealed similar levels of inflammation between the two groups. The gene was not important for adherence to or invasion of human epithelial cells and did not influence bacterial growth in rich medium, minimal medium, or cattle blood. In conclusion, a lack of bstA affects the pathogenicity of S Dublin by decreasing its virulence. Therefore, it might be regarded as an antivirulence gene in this serovar. Copyright © 2017 American Society for Microbiology.

Occurrence of plasmid-mediated quinolone resistance determinants and rmtB gene in Salmonella enterica serovar enteritidis and Typhimurium isolated from food-animal products in Tunisia.

PubMed

Al-Gallas, Nazek; Abbassi, Mohamed Salah; Gharbi, Becher; Manai, Molka; Ben Fayala, Mohamed N; Bichihi, Raghda; Al-Gallas, Amna; Ben Aissa, Ridha

2013-09-01

Four hundred and thirty Salmonella isolates, recovered from various food-animal products, were tested for nalidixic acid resistance, plasmid-mediated quinolone resistance, and genetic relationship. One hundred fifteen isolates (113 Salmonella serovar Enteritidis and two Salmonella serovar Typhimurium isolates) of 430 (26.7%) Salmonella isolates exhibited nalidixic acid resistance. Polymerase chain reaction screening for qnrA, qnrB, qnrS, qepA (encoding fluoroquinolones resistance) and rmtB (encoding aminoglycosides resistance) showed that 5 (1.16%) isolates were positive for qnr- and qepA-type genes, and the aac(6')-Ib-cr gene was observed in two (1.7%) Enteritidis isolates concomitantly with qnrA or qnrB. The co-occurrence of qepA and rmtB in one Typhimurium isolate is noteworthy. Pulsed-field gel electrophoresis revealed a high genetic homogeneity of nalidixic-resistant isolates and the persistence of clonal clusters over 4 years in different regions in Tunisia and from various food-animal products. To the best of our knowledge, this is the first report of co-occurrence of qepA and rmtB in a Salmonella strain.

Effect of Challenge Temperature and Solute Type on Heat Tolerance of Salmonella Serovars at Low Water Activity

PubMed Central

Mattick, K. L.; Jørgensen, F.; Wang, P.; Pound, J.; Vandeven, M. H.; Ward, L. R.; Legan, J. D.; Lappin-Scott, H. M.; Humphrey, T. J.

2001-01-01

Salmonella spp. are reported to have an increased heat tolerance at low water activity (aw; measured by relative vapor pressure [rvp]), achieved either by drying or by incorporating solutes. Much of the published data, however, cover only a narrow treatment range and have been analyzed by assuming first-order death kinetics. In this study, the death of Salmonella enterica serovar Typhimurium DT104 when exposed to 54 combinations of temperature (55 to 80°C) and aw (rvp 0.65 to 0.90, reduced using glucose-fructose) was investigated. The Weibull model (LogS = −btn) was used to describe microbial inactivation, and surface response models were developed to predict death rates for serovar Typhimurium at all points within the design surface. The models were evaluated with data generated by using six different Salmonella strains in place of serovar Typhimurium DT104 strain 30, two different solutes in place of glucose-fructose to reduce aw, or six low-aw foods artificially contaminated with Salmonella in place of the sugar broths. The data demonstrate that, at temperatures of ≥70°C, Salmonella cells at low aw were more heat tolerant than those at a higher aw but below 65°C the reverse was true. The same patterns were generated when sucrose (rvp 0.80 compared with 0.90) or NaCl (0.75 compared with 0.90) was used to reduce aw, but the extent of the protection afforded varied with solute type. The predictions of thermal death rates in the low-aw foods were usually fail-safe, but the few exceptions highlight the importance of validating models with specific foods that may have additional factors affecting survival. PMID:11526015

An rfaH Mutant of Salmonella enterica Serovar Typhimurium is Attenuated in Swine and Reduces Intestinal Colonization, Fecal Shedding, and Disease Severity Due to Virulent Salmonella Typhimurium

PubMed Central

Bearson, Bradley L.; Bearson, Shawn M. D.; Kich, Jalusa D.; Lee, In Soo

2014-01-01

Swine are often asymptomatic carriers of Salmonella spp., and interventions are needed to limit colonization of swine to enhance food safety and reduce environmental contamination. We evaluated the attenuation and potential vaccine use in pigs of a Salmonella enterica serovar Typhimurium mutant of rfaH, the gene encoding the RfaH antiterminator that prevents premature termination of long mRNA transcripts. Pigs inoculated with wild-type S. Typhimurium exhibited a significant elevation in average body temperature (fever) at 1 and 2 days post-inoculation; rfaH-inoculated pigs did not (n = 5/group). During the 7-day trial, a significant reduction of Salmonella in the feces, tonsils, and cecum were observed in the rfaH-inoculated pigs compared to wild-type inoculated pigs. To determine whether vaccination with the rfaH mutant could provide protection against wild-type S. Typhimurium challenge, two groups of pigs (n = 14/group) were intranasally inoculated with either the rfaH mutant or a PBS placebo at 6 and 8 weeks of age and challenged with the parental, wild-type S. Typhimurium at 11 weeks of age. The average body temperature was significantly elevated in the mock-vaccinated pigs at 1 and 2 days post-challenge, but not in the rfaH-vaccinated pigs. Fecal shedding at 2 and 3 days post-challenge and colonization of intestinal tract tissues at 7 days post-challenge by wild-type S. Typhimurium was significantly reduced in the rfaH-vaccinated pigs compared to mock-vaccinated pigs. Serological analysis using the IDEXX HerdChek Swine Salmonella Test Kit indicated that vaccination with the rfaH mutant did not stimulate an immune response against LPS. These results indicate that vaccination of swine with the attenuated rfaH mutant confers protection against challenge with virulent S. Typhimurium but does not interfere with herd level monitoring for Salmonella spp., thereby allowing for differentiation of infected from vaccinated animals (DIVA). PMID

Respective Roles of Culturable and Viable-but-Nonculturable Cells in the Heterogeneity of Salmonella enterica Serovar Typhimurium Invasiveness▿

PubMed Central

Passerat, Julien; Got, Patrice; Dukan, Sam; Monfort, Patrick

2009-01-01

The existence of Salmonella enterica serovar Typhimurium viable-but-nonculturable (VBNC) cells is a public health concern since they could constitute unrecognized sources of infection if they retain their pathogenicity. To date, many studies have addressed the ability of S. Typhimurium VBNC cells to remain infectious, but their conclusions are conflicting. An assumption could explain these conflicting results. It has been proposed that infectivity could be retained only temporarily after entry into the VBNC state and that most VBNC cells generated under intense stress could exceed the stage where they are still infectious. Using a Radioselectan density gradient centrifugation technique makes it possible to increase the VBNC-cell/culturable-cell ratio without increasing the exposure to stress and, consequently, to work with a larger proportion of newly VBNC cells. Here, we observed that (i) in the stationary phase, the S. Typhimurium population comprised three distinct subpopulations at 10, 24, or 48 h of culture; (ii) the VBNC cells were detected at 24 and 48 h; (iii) measurement of invasion gene (hilA, invF, and orgA) expression demonstrated that cells are highly heterogeneous within a culturable population; and (iv) invasion assays of HeLa cells showed that culturable cells from the different subpopulations do not display the same invasiveness. The results also suggest that newly formed VBNC cells are either weakly able or not able to successfully initiate epithelial cell invasion. Finally, we propose that at entry into the stationary phase, invasiveness may be one way for populations of S. Typhimurium to escape stochastic alteration leading to cell death. PMID:19525274

Lactic acid bacteria and bifidobacteria attenuate the proinflammatory response in intestinal epithelial cells induced by Salmonella enterica serovar Typhimurium.

PubMed

Carey, Christine M; Kostrzynska, Magdalena

2013-01-01

Inflammation is a physiological response to infections and tissue injury; however, abnormal immune responses can give rise to chronic inflammation and contribute to disease progression. Various dietary components, including probiotic lactic acid bacteria and prebiotics, have the potential to modulate intestinal inflammatory responses. One factor in particular, the chemokine interleukin-8 (IL-8, CXCL-8), is one of the major mediators of the inflammatory response. The purpose of this study was to investigate modulation of the inflammatory host response induced by Salmonella enterica serovar Typhimurium DT104 in the presence of selected probiotics and lactic acid bacteria (LAB) isolated from human sources, dairy products, and farm animals. IL-8 gene expression and protein production in HT-29 cells were evaluated by real-time PCR and ELISA, respectively. Pre-incubation of HT-29 cells with Lactobacillus kefir IM002, Bifidobacterium adolescentis FRP 61, Bifidobacterium longum FRP 68 and FRP 69, Bifidobacterium breve FRP 334, and Leuconostoc mesenteroides IM080 significantly inhibited IL-8 secretion induced by Salmonella Typhimurium DT104. Co-culture of selected probiotics and Salmonella Typhimurium DT104 reduced IL-8 production, while potential probiotics and LAB had no effect on IL-8 secretion in HT-29 cells preincubated with Salmonella Typhimurium DT104 prior to adding probiotics. Lactobacillus kefir IM002 supernatant also significantly reduced IL-8 production. In conclusion, our study suggests that probiotic bifidobacteria and LAB modulate cytokine induction and possess anti-inflammatory properties; however, the effectiveness is strain dependent.

Antibacterial activity and effects of Colla corii asini on Salmonella typhimurium invasion in vitro and in vivo.

PubMed

Park, Kwang-Il; Lee, Mi-Ra; Oh, Tae-Woo; Kim, Kwang-Youn; Ma, Jin-Yeul

2017-12-04

Salmonella enterica serovar Typhimurium is a foodborne pathogen that triggers inflammatory responses in the intestines of humans and livestock. Colla corii asini is a traditional medicine used to treat gynecologic and chronic diseases in Korea and China. However, the antibacterial activity of Colla corii asini has been unknown. In this study, we investigated the antibacterial activity and effects of Colla corii asini extract on Salmonella typhimurium invasion. To tested for antibacterial effects of Colla corii asini extracts, we confirmed the agar diffusion using Luria solid broth medium. Also, we determined the MIC (minimum inhibitory concentration) and the MBC (minimum bactericidal concentration) value of the Colla corii asini ethanol extract (CEE) by using two-fold serial dilution methods. We evaluated the expression of salmonella invasion proteins including SipA, SipB and SipC by using Western blot and qPCR at the concentration of CEE without inhibition of bacterial growth. In vitro and vivo, we determined the inhibitory effect of invasion of S. typhimurium on CEE by using gentamicin assay and S. typhimurium-infected mice. CEE significantly inhibited the growth of Salmonella typhimurium in an agar diffuse assay and had an MIC of 0.78 mg/ml and an MBC of 1.56 mg/ml. Additionally, CEE reduced Salmonella typhimurium cell invasion via the inhibition of Salmonella typhimurium invasion proteins, such as SipA, SipB and SipC. Furthermore, CEE significantly suppressed invasion in the small intestines (ilea) of mice injected with Salmonella typhimurium. These findings show that Colla corii asini exerts antibacterial activity and suppresses Salmonella typhimurium invasion in vitro and in vivo. Together, these findings demonstrate that Colla corii asini is a potentially useful therapeutic herbal medicine for treating salmonella-mediated diseases.

Genomic Comparison of Non-Typhoidal Salmonella enterica Serovars Typhimurium, Enteritidis, Heidelberg, Hadar and Kentucky Isolates from Broiler Chickens

PubMed Central

Dhanani, Akhilesh S.; Block, Glenn; Dewar, Ken; Forgetta, Vincenzo; Topp, Edward; Beiko, Robert G.; Diarra, Moussa S.

2015-01-01

Background Non-typhoidal Salmonella enterica serovars, associated with different foods including poultry products, are important causes of bacterial gastroenteritis worldwide. The colonization of the chicken gut by S. enterica could result in the contamination of the environment and food chain. The aim of this study was to compare the genomes of 25 S. enterica serovars isolated from broiler chicken farms to assess their intra- and inter-genetic variability, with a focus on virulence and antibiotic resistance characteristics. Methodology/Principal Finding The genomes of 25 S. enterica isolates covering five serovars (ten Typhimurium including three monophasic 4,[5],12:i:, four Enteritidis, three Hadar, four Heidelberg and four Kentucky) were sequenced. Most serovars were clustered in strongly supported phylogenetic clades, except for isolates of serovar Enteritidis that were scattered throughout the tree. Plasmids of varying sizes were detected in several isolates independently of serovars. Genes associated with the IncF plasmid and the IncI1 plasmid were identified in twelve and four isolates, respectively, while genes associated with the IncQ plasmid were found in one isolate. The presence of numerous genes associated with Salmonella pathogenicity islands (SPIs) was also confirmed. Components of the type III and IV secretion systems (T3SS and T4SS) varied in different isolates, which could explain in part, differences of their pathogenicity in humans and/or persistence in broilers. Conserved clusters of genes in the T3SS were detected that could be used in designing effective strategies (diagnostic, vaccination or treatments) to combat Salmonella. Antibiotic resistance genes (CMY, aadA, ampC, florR, sul1, sulI, tetAB, and srtA) and class I integrons were detected in resistant isolates while all isolates carried multidrug efflux pump systems regardless of their antibiotic susceptibility profile. Conclusions/Significance This study showed that the predominant

Genomic Comparison of Non-Typhoidal Salmonella enterica Serovars Typhimurium, Enteritidis, Heidelberg, Hadar and Kentucky Isolates from Broiler Chickens.

PubMed

Dhanani, Akhilesh S; Block, Glenn; Dewar, Ken; Forgetta, Vincenzo; Topp, Edward; Beiko, Robert G; Diarra, Moussa S

2015-01-01

Non-typhoidal Salmonella enterica serovars, associated with different foods including poultry products, are important causes of bacterial gastroenteritis worldwide. The colonization of the chicken gut by S. enterica could result in the contamination of the environment and food chain. The aim of this study was to compare the genomes of 25 S. enterica serovars isolated from broiler chicken farms to assess their intra- and inter-genetic variability, with a focus on virulence and antibiotic resistance characteristics. The genomes of 25 S. enterica isolates covering five serovars (ten Typhimurium including three monophasic 4,[5],12:i:, four Enteritidis, three Hadar, four Heidelberg and four Kentucky) were sequenced. Most serovars were clustered in strongly supported phylogenetic clades, except for isolates of serovar Enteritidis that were scattered throughout the tree. Plasmids of varying sizes were detected in several isolates independently of serovars. Genes associated with the IncF plasmid and the IncI1 plasmid were identified in twelve and four isolates, respectively, while genes associated with the IncQ plasmid were found in one isolate. The presence of numerous genes associated with Salmonella pathogenicity islands (SPIs) was also confirmed. Components of the type III and IV secretion systems (T3SS and T4SS) varied in different isolates, which could explain in part, differences of their pathogenicity in humans and/or persistence in broilers. Conserved clusters of genes in the T3SS were detected that could be used in designing effective strategies (diagnostic, vaccination or treatments) to combat Salmonella. Antibiotic resistance genes (CMY, aadA, ampC, florR, sul1, sulI, tetAB, and srtA) and class I integrons were detected in resistant isolates while all isolates carried multidrug efflux pump systems regardless of their antibiotic susceptibility profile. This study showed that the predominant Salmonella serovars in broiler chickens harbor genes encoding adhesins

Complete Genome Sequence of Salmonella enterica Serovar Typhimurium Strain YU15 (Sequence Type 19) Harboring the Salmonella Genomic Island 1 and Virulence Plasmid pSTV

PubMed Central

Calva, Edmundo; Puente, José L.; Zaidi, Mussaret B.

2016-01-01

The complete genome of Salmonella enterica subsp. enterica serovar Typhimurium sequence type 19 (ST19) strain YU15, isolated in Yucatán, Mexico, from a human baby stool culture, was determined using PacBio technology. The chromosome contains five intact prophages and the Salmonella genomic island 1 (SGI1). This strain carries the Salmonella virulence plasmid pSTV. PMID:27081132

Salmonella enterica serovar Typhimurium in Mauritius linked to consumption of marlin mousse.

PubMed

Issack, Mohammad I; Hendriksen, Rene S; Lun, Phimy Lan Keng; Lutchun, Ram K S; Aarestrup, Frank M

2009-01-01

We report the first outbreak of salmonellosis caused by consumption of contaminated marlin mousse. Between 29 October and 5 November 2008, at least 53 persons developed diarrheal illness, all with a history of eating marlin mousse. Salmonella spp. that did not produce gas from glucose was isolated from stools of 26 affected patients and blood culture from one patient. Salmonella sp. isolates with the same phenotype were isolated in three samples of marlin mousse manufactured on 27 October 2008. The constituents of the mousse were smoked marlin, raw eggs, bovine gelatin, oil, and cream. A laboratory investigation of one sample of marlin mousse manufactured 3 days later, and the individual ingredients sampled a week after production of the contaminated batch were all negative for Salmonella. Serotyping and minimum inhibitory concentration determination were performed on 12 patient isolates related to the outbreak and two mousse isolates. All isolates belonged to Salmonella serovar Typhimurium and were pansusceptible to all antimicrobials tested. Pulsed-field gel electrophoresis revealed that all the isolates were indistinguishable, thus implicating the mousse as the vehicle of the outbreak.

Proteins from latex of Calotropis procera prevent septic shock due to lethal infection by Salmonella enterica serovar Typhimurium.

PubMed

Lima-Filho, José V; Patriota, Joyce M; Silva, Ayrles F B; Filho, Nicodemos T; Oliveira, Raquel S B; Alencar, Nylane M N; Ramos, Márcio V

2010-06-16

The latex of Calotropis procera has been used in traditional medicine to treat different inflammatory diseases. The anti-inflammatory activity of latex proteins (LP) has been well documented using different inflammatory models. In this work the anti-inflammatory protein fraction was evaluated in a true inflammatory process by inducing a lethal experimental infection in the murine model caused by Salmonella enterica Subsp. enterica serovar Typhimurium. Experimental Swiss mice were given 0.2 ml of LP (30 or 60 mg/kg) by the intraperitoneal route 24 h before or after lethal challenge (0.2 ml) containing 10(6) CFU/ml of Salmonella Typhimurium using the same route of administration. All the control animals succumbed to infection within 6 days. When given before bacterial inoculums LP prevented the death of mice, which remained in observation until day 28. Even, LP-treated animals exhibited only discrete signs of infection which disappeared latter. LP fraction was also protective when given orally or by subcutaneous route. Histopathological examination revealed that necrosis and inflammatory infiltrates were similar in both the experimental and control groups on days 1 and 5 after infection. LP activity did not clear Salmonella Typhimurium, which was still present in the spleen at approximately 10(4) cells/g of organ 28 days after challenge. However, no bacteria were detected in the liver at this stage. LP did not inhibit bacterial growth in culture medium at all. In the early stages of infection bacteria population was similar in organs and in the peritoneal fluid but drastically reduced in blood. Titration of TNF-alpha in serum revealed no differences between experimental and control groups on days 1 and 5 days after infection while IL-12 was only discretely diminished in serum of experimental animals on day 5. Moreover, cultured macrophages treated with LP and stimulated by LPS released significantly less IL-1beta. LP-treated mice did not succumb to septic shock when

Exposure of Salmonella enterica Serovar Typhimurium to Three Humectants Used in the Food Industry Induces Different Osmoadaptation Systems.

PubMed

Finn, Sarah; Rogers, Lisa; Händler, Kristian; McClure, Peter; Amézquita, Alejandro; Hinton, Jay C D; Fanning, Séamus

2015-10-01

Common salt (NaCl) is frequently used by the food industry to add flavor and to act as a humectant in order to reduce the water content of a food product. The improved health awareness of consumers is leading to a demand for food products with reduced salt content; thus, manufacturers require alternative water activity-reducing agents which elicit the same general effects as NaCl. Two examples include KCl and glycerol. These agents lower the water activity of a food matrix and also contribute to limit the growth of the microbiota, including foodborne pathogens. Little is currently known about how foodborne pathogens respond to these water activity-lowering agents. Here we examined the response of Salmonella enterica serovar Typhimurium 4/74 to NaCl, KCl, and glycerol at three time points, using a constant water activity level, compared with the response of a control inoculum. All conditions induced the upregulation of gluconate metabolic genes after 6 h of exposure. Bacteria exposed to NaCl and KCl demonstrated the upregulation of the osmoprotective transporter mechanisms encoded by the proP, proU, and osmU (STM1491 to STM1494) genes. Glycerol exposure elicited the downregulation of these osmoadaptive mechanisms but stimulated an increase in lipopolysaccharide and membrane protein-associated genes after 1 h. The most extensive changes in gene expression occurred following exposure to KCl. Because many of these genes were of unknown function, further characterization may identify KCl-specific adaptive processes that are not stimulated by NaCl. This study shows that the response of S. Typhimurium to different humectants does not simply reflect reduced water activity and likely involves systems that are linked to specific humectants. Copyright © 2015 Finn et al.

Evidence for Lack of Acquisition of Tolerance in Salmonella enterica Serovar Typhimurium ATCC 14028 after Exposure to Subinhibitory Amounts of Origanum vulgare L. Essential Oil and Carvacrol

PubMed Central

Luz, Isabelle da Silva; Gomes Neto, Nelson Justino; Tavares, Adassa Gama; Nunes, Pollyana Campos; Magnani, Marciane

2012-01-01

Overnight exposure of Salmonella enterica serovar Typhimurium to sublethal amounts of Origanum vulgare essential oil (OV) and carvacrol (CAR) did not result in direct and cross-bacterial protection. Cells subcultured with increasing amounts of OV or CAR survived up to the MIC of either compound, revealing few significant changes in bacterial susceptibility. PMID:22544235

Novel DNA binding and regulatory activities for s54 (RpoN) in Salmonella Typhimurium 14028s

USDA-ARS?s Scientific Manuscript database

Salmonella enterica subspecies enterica serovar Typhimurium, the causative agent of gastrointestinal disease and septicemia in humans, has been extensively studied, providing a comprehensive model system in which to study how pathogens respond to the rapidly changing conditions during persistence in...

Genomic Analysis of Salmonella enterica Serovar Typhimurium DT160 Associated with a 14-Year Outbreak, New Zealand, 1998–2012

PubMed Central

Benschop, Jackie; Biggs, Patrick J.; Marshall, Jonathan C.; Hayman, David T.S.; Carter, Philip E.; Midwinter, Anne C.; Mather, Alison E.; French, Nigel P.

2017-01-01

During 1998–2012, an extended outbreak of Salmonella enterica serovar Typhimurium definitive type 160 (DT160) affected >3,000 humans and killed wild birds in New Zealand. However, the relationship between DT160 within these 2 host groups and the origin of the outbreak are unknown. Whole-genome sequencing was used to compare 109 Salmonella Typhimurium DT160 isolates from sources throughout New Zealand. We provide evidence that DT160 was introduced into New Zealand around 1997 and rapidly propagated throughout the country, becoming more genetically diverse over time. The genetic heterogeneity was evenly distributed across multiple predicted functional protein groups, and we found no evidence of host group differentiation between isolates collected from human, poultry, bovid, and wild bird sources, indicating ongoing transmission between these host groups. Our findings demonstrate how a comparative genomic approach can be used to gain insight into outbreaks, disease transmission, and the evolution of a multihost pathogen after a probable point-source introduction. PMID:28516864

Higher Storage Temperature Causes Greater Salmonella enterica Serovar Typhimurium Internal Penetration of Artificially Contaminated, Commercially Available, Washed Free Range Eggs.

PubMed

Whiley, Alice; Fallowfield, Howard; Ross, Kirstin; McEvoy, Vanessa; Whiley, Harriet

2016-07-01

Foodborne salmonellosis is a major public health concern, with contaminated eggs identified as a significant source of infection. In Australia, the most prevalent cause of salmonellosis from eggs is Salmonella enterica subsp. enterica serovar Typhimurium. This study explored the effect of temperature after 1, 7, 14, 21, and 28 days of storage on commercially available washed free range eggs, artificially contaminated with Salmonella Typhimurium on the external surface. At each time point, the external surface of the egg, the crushed eggshell, and the internal egg yolk and albumen were analyzed for Salmonella. After 28 days of storage, 25% of eggs stored at 4°C, 50% of eggs stored at 14°C, and 100% of eggs stored at 23 and 35°C were internally contaminated with Salmonella. After 1 day of storage, more than 50% of all eggs had Salmonella present in the crushed shell after the external surface had been disinfected with ethanol. This is the first study to demonstrate that refrigeration reduced the potential for Salmonella Typhimurium to penetrate the eggshell membrane and internally contaminate table eggs commercially available in Australia. It also suggests that the processes of cracking eggs may be a source of cross-contamination within the kitchen.

β-1,3/1,6-Glucan alleviated intestinal mucosal barrier impairment of broiler chickens challenged with Salmonella enterica serovar Typhimurium.

PubMed

Shao, Yujing; Guo, Yuming; Wang, Zhong

2013-07-01

This study investigated the protective effect of β-1,3/1,6-glucan on gut morphology, intestinal epithelial tight junctions, and bacterial translocation of broiler chickens challenged with Salmonella enterica serovar Typhimurium. Ninety Salmonella-free Arbor Acre male broiler chickens were randomly divided into 3 groups: negative control group (NC), Salmonella Typhimurium-infected positive group (PC), and the Salmonella Typhimurium-infected group with dietary 100 mg/kg of β-1,3/1,6-glucan supplementation (T) to determine the effect of β-1,3/1,6-glucan on intestinal barrier function. Salmonella Typhimurium challenge alone significantly decreased villus height (P < 0.001), villus height/crypt depth ratio (P < 0.05), and the number of goblet cells (P < 0.001) in the jejunum at 14 d postinfection (dpi), but significantly increased the number of intestinal secretory IgA (sIgA)-expressing cells at 14 dpi (P < 0.01) and total sIgA levels in the jejunum at 7 (P < 0.05) and 14 dpi (P < 0.01) compared with the unchallenged birds (NC). Dietary β-1,3/1,6-glucan supplementation not only significantly increased villus height, villus height/crypt depth ratio, and the number of goblet cells (P < 0.01), but also increased the number of sIgA-expressing cells (P < 0.05) and sIgA content in the jejunum at 14 dpi (P < 0.01) in birds challenged with Salmonella Typhimurium in comparison with Salmonella Typhimurium challenge alone. β-1,3/1,6-Glucan addition had significant inhibitory effects (P < 0.05) on cecal Salmonella colonization levels and liver Salmonella invasion of the Salmonella Typhimurium-infected birds compared with the PC group. Intestinal tight junction proteins claudin-1, claudin-4, and occludin mRNA expression in the jejunum at 14 dpi was significantly decreased by Salmonella Typhimurium challenge alone (P < 0.01) compared with that of the NC group, whereas β-1,3/1,6-glucan supplementation significantly increased claudin-1 and occludin mRNA expression (P < 0.01) at

Salmonella enterica serovar Typhimurium utilizes the ClpPX and Lon proteases for optimal fitness in the ceca of chickens.

PubMed

Troxell, Bryan

2016-07-01

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a leading cause of salmonellosis. Poultry and poultry products are implicated in transmission of Salmonella to humans. In 2013, an outbreak of S Typhimurium occurred that comprised 39 states within the United States and was associated with backyard flocks of chickens. Colonization of the avian host by S Typhimurium requires numerous genetic factors encoded within the bacterium. Of particular interest are genetic factors induced by alternative sigma factors within S Typhimurium since these genetic elements are important for adaptation to different environmental stresses. The heat shock response is a dedicated change in gene regulation within bacteria in response to several stresses, specifically growth at 42°C. Because chickens have a higher body temperature than other animals (42°C) the hypothesis was tested that components of the heat shock response are important for optimal fitness within the chicken. To this end, deletion of the heat shock proteases clpPX (BTNC0022) or lon (BTNC0021) was accomplished and the bacterial fitness in vivo was compared to the "wild-type" strain (NC1040) using a competition assay. One-day-old chicks were orally gavaged with an equal mixture of NC1040 and either BTNC0022 or BTNC0021. Quantification of viable bacteria over time by using plate counts indicated that deletion of either heat shock protease resulted in significantly reduced colonization of the chicken ceca compared to the wild-type strain. To satisfy the molecular Koch's postulates, clpPX and lon mutants were complemented in trans using a low-copy number plasmid for additional in vivo experiments. Complementation studies confirmed the importance of either heat shock protease to colonization of the chicken ceca. This report demonstrated that both ClpPX and Lon were important for optimal fitness within chickens. Moreover, these results suggested that components of the heat shock may be critical factors used by S

Changes in the prevalence of Salmonella serovars associated swine production and correlations of avian, bovine and swine-associated serovars with human-associated serovars in the United States (1997-2015).

PubMed

Yuan, C; Krull, A; Wang, C; Erdman, M; Fedorka-Cray, P J; Logue, C M; O'Connor, A M

2018-04-23

As Salmonella enterica is an important pathogen of food animals, surveillance programmes for S. enterica serovars have existed for many years in the United States. Surveillance programmes serve many purposes, one of which is to evaluate alterations in the prevalence of serovars that may signal changes in the ecology of the target organism. The primary aim of this study was to evaluate changes in the proportion of S. enterica serovars isolated from swine over a near 20-year observation period (1997-2015) using four longitudinal data sets from different food animal species. The secondary aim was to evaluate correlations between changes in S. enterica serovars frequently recovered from food animals and changes in S. enterica serovars associated with disease in humans. We found decreasing proportions of S. enterica serovar Typhimurium, serovar Derby and serovar Heidelberg and increasing proportions of S. enterica serovar 4,[5],12:i:-, serovar Infantis and serovar Johannesburg in swine over time. We also found positive correlations for the yearly changes in S. enterica serovar 4,[5],12:i:-, serovar Anatum and serovar Johannesburg between swine and human data; in S. enterica Worthington between avian and human data; and in S. enterica serovar 4,[5],12:i:- between bovine and human data. We found negative correlations for the yearly changes in S. enterica serovar 4,[5],12:i:- and serovar Johannesburg between avian and human data. © 2018 Blackwell Verlag GmbH.

A Mutation in the Putative Lysl-tRNA Synthetase Gene, PoxR of Salmonella enterica Serovar Typhimurium Results in Altered Protein Production, Elevated Susceptibility to Environmental Challenges and Decreased Swine Colonization

USDA-ARS?s Scientific Manuscript database

Using signature-tagged mutagenesis, a mutation in the poxR gene of Salmonella enterica serovar Typhimurium was identified with decreased survival in an ex vivo swine stomach content assay(Bearson et al. Appl Environ Microbiol. 72:2829-36). Gastrointestinal colonization and fecal shedding of the pox...

Salmonella Enterica Serovar Typhimurium BipA Exhibits Two Distinct Ribosome Binding Modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

deLivron, M.; Robinson, V

BipA is a highly conserved prokaryotic GTPase that functions to influence numerous cellular processes in bacteria. In Escherichia coli and Salmonella enterica serovar Typhimurium, BipA has been implicated in controlling bacterial motility, modulating attachment and effacement processes, and upregulating the expression of virulence genes and is also responsible for avoidance of host defense mechanisms. In addition, BipA is thought to be involved in bacterial stress responses, such as those associated with virulence, temperature, and symbiosis. Thus, BipA is necessary for securing bacterial survival and successful invasion of the host. Steady-state kinetic analysis and pelleting assays were used to assess themore » GTPase and ribosome-binding properties of S. enterica BipA. Under normal bacterial growth, BipA associates with the ribosome in the GTP-bound state. However, using sucrose density gradients, we demonstrate that the association of BipA and the ribosome is altered under stress conditions in bacteria similar to those experienced during virulence. The data show that this differential binding is brought about by the presence of ppGpp, an alarmone that signals the onset of stress-related events in bacteria.« less

Induction of Fatty Acid Composition Modifications and Tolerance to Biocides in Salmonella enterica Serovar Typhimurium by Plant-Derived Terpenes▿

PubMed Central

Dubois-Brissonnet, Florence; Naïtali, Murielle; Mafu, Akier Assanta; Briandet, Romain

2011-01-01

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 extracted from aromatic plants: thymol, carvacrol, citral, and eugenol, or combinations thereof. Bacterial adaptation in these conditions was demonstrated by changes in membrane fatty acid composition showing (i) limitation of the cyclization of unsaturated fatty acids to cyclopropane fatty acids when cells entered the stationary phase and (ii) bacterial membrane saturation. Furthermore, we demonstrated an increased cell resistance to the bactericidal activity of two biocides (peracetic acid and didecyl dimethyl ammonium bromide). The implications of membrane modifications in terms of hindering the penetration of antimicrobials through the bacterial membrane are discussed. PMID:21131520

The transcriptional programme of Salmonella enterica serovar Typhimurium reveals a key role for tryptophan metabolism in biofilms

PubMed Central

2009-01-01

Background Biofilm formation enhances the capacity of pathogenic Salmonella bacteria to survive stresses that are commonly encountered within food processing and during host infection. The persistence of Salmonella within the food chain has become a major health concern, as biofilms can serve as a reservoir for the contamination of food products. While the molecular mechanisms required for the survival of bacteria on surfaces are not fully understood, transcriptional studies of other bacteria have demonstrated that biofilm growth triggers the expression of specific sets of genes, compared with planktonic cells. Until now, most gene expression studies of Salmonella have focused on the effect of infection-relevant stressors on virulence or the comparison of mutant and wild-type bacteria. However little is known about the physiological responses taking place inside a Salmonella biofilm. Results We have determined the transcriptomic and proteomic profiles of biofilms of Salmonella enterica serovar Typhimurium. We discovered that 124 detectable proteins were differentially expressed in the biofilm compared with planktonic cells, and that 10% of the S. Typhimurium genome (433 genes) showed a 2-fold or more change in the biofilm compared with planktonic cells. The genes that were significantly up-regulated implicated certain cellular processes in biofilm development including amino acid metabolism, cell motility, global regulation and tolerance to stress. We found that the most highly down-regulated genes in the biofilm were located on Salmonella Pathogenicity Island 2 (SPI2), and that a functional SPI2 secretion system regulator (ssrA) was required for S. Typhimurium biofilm formation. We identified STM0341 as a gene of unknown function that was needed for biofilm growth. Genes involved in tryptophan (trp) biosynthesis and transport were up-regulated in the biofilm. Deletion of trpE led to decreased bacterial attachment and this biofilm defect was restored by exogenous

Expression of Toll-like receptors, interleukin 8, macrophage migration inhibitory factor, and osteopontin in tissues from pigs challenged with Salmonella enterica serovar Typhimurium or serovar Choleraesuis.

PubMed

Burkey, T E; Skjolaas, K A; Dritz, S S; Minton, J E

2007-02-15

Two serovars of Salmonella enterica, namely serovar Typhimurium (ST) and serovar Choleraesuis (SC) account for the vast majority of clinical cases of swine salmonellosis worldwide. These serovars are thought to be transmitted among pigs in production settings mainly through fecal-oral routes. Yet, few studies have evaluated effects of these serovars on expression of innate immune targets when presented to pigs via repeated oral dosing in an attempt to model transmission in production settings. Thus, a primary objective of the current experiments was to evaluate expression of Toll-like receptors (TLR) and selected chemoattractive mediators (interleukin 8, IL8; macrophage migration inhibitory factor, MIF; osteopontin, OPN) in tissues from pigs exposed to ST or SC that had been transformed with kanamycin resistance and green (STG) or red (SCR) fluorescent protein to facilitate isolation from pen fecal samples. In vitro studies confirmed that STG and SCR largely (though not completely) retained their ability to upregulate IL8 and CC chemokine ligand 20 (CCL20) in cultured swine jejunal epithelial cells. Transformed bacteria were then fed to pigs in an in vivo study to determine tissue specific effects on mRNA relative expression. Pigs were fed cookie dough inoculated with bacteria on days 0, 3, 7, and 10 with 10(8)CFU STG (n=8) or SCR (n=8), while control (CTL) pigs (n=8) received dough without bacteria. Animals were sacrificed 14 days from the initial bacterial challenge and samples of tonsil, jejunum, ileum, colon, mesenteric lymph node (MLN), spleen, and liver were removed for subsequent RNA isolation. Expression of mRNA in tissues was determined using real-time quantitative PCR and expressed relative to 18S rRNA. Within CTL pigs, when expressed relative to the content in liver, mRNA for all targets demonstrated substantial tissue effects (P<0.001 for all TLR; MIF, and OPN; P<0.05 for IL8). Feeding STG and SCR resulted in significant (P

Enhancement of Th1-biased protective immunity against avian influenza H9N2 virus via oral co-administration of attenuated Salmonella enterica serovar Typhimurium expressing chicken interferon-α and interleukin-18 along with an inactivated vaccine

PubMed Central

2012-01-01

Background Control of currently circulating re-assorted low-pathogenicity avian influenza (LPAI) H9N2 is a major concern for both animal and human health. Thus, an improved LPAI H9N2 vaccination strategy is needed to induce complete immunity in chickens against LPAI H9N2 virus strains. Cytokines play a crucial role in mounting both the type and extent of an immune response generated following infection with a pathogen or after vaccination. To improve the efficacy of inactivated LPAI H9N2 vaccine, attenuated Salmonella enterica serovar Typhimurium was used for oral co-administration of chicken interferon-α (chIFN-α) and chicken interleukin-18 (chIL-18) as natural immunomodulators. Results Oral co-administration of S. enterica serovar Typhimurium expressing chIFN-α and chIL-18, prior to vaccination with inactivated AI H9N2 vaccine, modulated the immune response of chickens against the vaccine antigen through enhanced humoral and Th1-biased cell-mediated immunity, compared to chickens that received single administration of S. enterica serovar Typhimurium expressing either chIFN-α or chIL-18. To further test the protective efficacy of this improved vaccination regimen, immunized chickens were intra-tracheally challenged with a high dose of LPAI H9N2 virus. Combined administration of S. enterica serovar Typhimurium expressing chIFN-α and chIL-18 showed markedly enhanced protection compared to single administration of the construct, as determined by mortality, clinical severity, and feed and water intake. This enhancement of protective immunity was further confirmed by reduced rectal shedding and replication of AIV H9N2 in different tissues of challenged chickens. Conclusions Our results indicate the value of combined administration of chIFN-α and chIL-18 using a Salmonella vaccine strain to generate an effective immunization strategy in chickens against LPAI H9N2. PMID:22776696

aroA-Deficient Salmonella enterica Serovar Typhimurium Is More Than a Metabolically Attenuated Mutant

PubMed Central

Frahm, Michael; Kocijancic, Dino; Rohde, Manfred; Eckweiler, Denitsa; Bielecka, Agata; Bueno, Emilio; Cava, Felipe; Abraham, Wolf-Rainer; Curtiss, Roy; Häussler, Susanne; Erhardt, Marc; Weiss, Siegfried

2016-01-01

ABSTRACT Recombinant attenuated Salmonella enterica serovar Typhimurium strains are believed to act as powerful live vaccine carriers that are able to elicit protection against various pathogens. Auxotrophic mutations, such as a deletion of aroA, are commonly introduced into such bacteria for attenuation without incapacitating immunostimulation. In this study, we describe the surprising finding that deletion of aroA dramatically increased the virulence of attenuated Salmonella in mouse models. Mutant bacteria lacking aroA elicited increased levels of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α) after systemic application. A detailed genetic and phenotypic characterization in combination with transcriptomic and metabolic profiling demonstrated that ΔaroA mutants display pleiotropic alterations in cellular physiology and lipid and amino acid metabolism, as well as increased sensitivity to penicillin, complement, and phagocytic uptake. In concert with other immunomodulating mutations, deletion of aroA affected flagellin phase variation and gene expression of the virulence-associated genes arnT and ansB. Finally, ΔaroA strains displayed significantly improved tumor therapeutic activity. These results highlight the importance of a functional shikimate pathway to control homeostatic bacterial physiology. They further highlight the great potential of ΔaroA-attenuated Salmonella for the development of vaccines and cancer therapies with important implications for host-pathogen interactions and translational medicine. PMID:27601574

DksA-dependent resistance of Salmonella enterica serovar Typhimurium against the antimicrobial activity of inducible nitric oxide synthase.

PubMed

Henard, Calvin A; Vázquez-Torres, Andrés

2012-04-01

In coordination with the ppGpp alarmone, the RNA polymerase regulatory protein DksA controls the stringent response of eubacteria, negatively regulating transcription of translational machinery and directly activating amino acid promoters and de novo amino acid biosynthesis. Given the effects of nitric oxide (NO) on amino acid biosynthetic pathways and the intimate relationship of DksA with amino acid synthesis and transport, we tested whether DksA contributes to the resistance of Salmonella to reactive nitrogen species (RNS). Our studies show that the zinc finger predicted to position DksA in the secondary channel of the RNA polymerase is essential for the resistance of Salmonella enterica serovar Typhimurium to RNS in a murine model of systemic salmonellosis. Despite exhibiting auxotrophies for various amino acids, ΔdksA mutant Salmonella strains regain virulence in mice lacking inducible NO synthase (iNOS). DksA is also important for growth of this intracellular pathogen in the presence of NO congeners generated by iNOS during the innate response of murine macrophages. Accordingly, dksA mutant Salmonella strains are hypersusceptible to chemically generated NO, a phenotype that can be prevented by adding amino acids. The DksA-dependent antinitrosative defenses do not rely on the Hmp flavohemoprotein that detoxifies NO to NO(3)(-) and appear to operate independently of the ppGpp alarmone. Our investigations are consistent with a model by which NO produced in the innate response to Salmonella exerts considerable pressure on amino acid biosynthesis. The cytotoxicity of NO against Salmonella amino acid biosynthetic pathways is antagonized in great part by the DksA-dependent regulation of amino acid biosynthesis and transport.

Isolation and characterization of Salmonella Enteritidis and Salmonella Typhimurium from chicken meat in Egypt.

PubMed

Tarabees, Reda; Elsayed, Mohamed S A; Shawish, Reyad; Basiouni, Shereen; Shehata, Awad A

2017-04-30

Salmonella enterica serovars Enteritidis and Typhimurium represent the major serovars associated with human salmonellosis. Contamination of meat products with these serovars is considered the main source of infection. In this study, 100 raw chicken meat samples were investigated for the presence of Salmonella spp., which were subsequently identified based on biochemical and serological tests as well as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) profile. Furthermore, the isolated serovars were examined using multiplex polymerase chain reaction (PCR) for the presence of virulence genes suspected to have a role in infection. S. Enteritidis was isolated from two samples (2%), while S. Typhimurium was isolated from three samples (3%) of chicken meat. Of the 17 examined virulence genes using multiplex PCR, the sitC, sopB, sifA, lpfC, spaN, sipB, invA, spiA, and msgA genes were detected in S. Enteritidis. However, the sitC, iroN, sopB, sifA, lpfC, spaN, sipB, invA, and tolC genes were successfully amplified in S. Typhimurium. The detection of S. Enteritidis and S. Typhimurium in meat, even at low incidence, has important implications. In addition, the data presented here is the first attempt to identify a wide range of virulence genes in Egyptian Salmonella isolates recovered from meat products. A strict public health and food safety regime is urgently needed in order to decrease the human health hazard risk associated with salmonellosis.

Negative supercoiling of DNA by gyrase is inhibited in Salmonella enterica serovar Typhimurium during adaptation to acid stress.

PubMed

Colgan, Aoife M; Quinn, Heather J; Kary, Stefani C; Mitchenall, Lesley A; Maxwell, Anthony; Cameron, Andrew D S; Dorman, Charles J

2018-03-01

DNA in intracellular Salmonella enterica serovar Typhimurium relaxes during growth in the acidified (pH 4-5) macrophage vacuole and DNA relaxation correlates with the upregulation of Salmonella genes involved in adaptation to the macrophage environment. Bacterial ATP levels did not increase during adaptation to acid pH unless the bacterium was deficient in MgtC, a cytoplasmic-membrane-located inhibitor of proton-driven F 1 F 0 ATP synthase activity. Inhibiting ATP binding by DNA gyrase and topo IV with novobiocin enhanced the effect of low pH on DNA relaxation. Bacteria expressing novobiocin-resistant (Nov R ) derivatives of gyrase or topo IV also exhibited DNA relaxation at acid pH, although further relaxation with novobiocin was not seen in the strain with Nov R gyrase. Thus, inhibition of the negative supercoiling activity of gyrase was the primary cause of enhanced DNA relaxation in drug-treated bacteria. The Salmonella cytosol reaches pH 5-6 in response to an external pH of 4-5: the ATP-dependent DNA supercoiling activity of purified gyrase was progressively inhibited by lowering the pH in this range, as was the ATP-dependent DNA relaxation activity of topo IV. We propose that DNA relaxation in Salmonella within macrophage is due to acid-mediated impairment of the negative supercoiling activity of gyrase. © 2018 John Wiley & Sons Ltd.

Human isolates of Salmonella enterica serovar Typhimurium from Taiwan displayed significantly higher levels of antimicrobial resistance than those from Denmark.

PubMed

Torpdahl, Mia; Lauderdale, Tsai-Ling; Liang, Shiu-Yun; Li, Ishien; Wei, Sung-Hsi; Chiou, Chien-Shun

2013-02-01

Salmonella enterica serovar Typhimurium is a major zoonotic pathogen with a high prevalence of antimicrobial resistance. This pathogen can disseminate across borders and spread far distances via the food trade and international travel. In this study, we compared the genotypes and antimicrobial resistance of 378 S. Typhimurium isolates collected in Taiwan and Denmark between 2009 and 2010. Genotyping revealed that many S. Typhimurium strains were concurrently circulating in Taiwan, Denmark and other countries in 2009 and 2010. When compared to the isolates collected from Denmark, the isolates from Taiwan displayed a significantly higher level of resistance to 11 of the 12 tested antimicrobials. Seven genetic clusters (A-G) were designated for the isolates. A high percentage of the isolates in genetic clusters C, F and G were multidrug-resistant. Of the isolates in cluster C, 79.2% were ASSuT-resistant, characterized by resistance to ampicillin, streptomycin, sulfamethoxazole, and tetracycline. In cluster F, 84.1% of the isolates were ACSSuT-resistant (resistant to ASSuT and chloramphenicol). Cluster G was unique to Taiwan and characterized in most isolates by the absence of three VNTRs (ST20, ST30 and STTR6) as well as a variety of multidrug resistance profiles. This cluster exhibited very high to extremely high levels of resistance to several first-line drugs, and among the seven clusters, it displayed the highest levels of resistance to cefotaxime and ceftazidime, ciprofloxacin and gentamicin. The high prevalence of antimicrobial resistance in S. Typhimurium from Taiwan highlights the necessity to strictly regulate the use of antimicrobials in the agriculture and human health care sectors. Copyright © 2012 Elsevier B.V. All rights reserved.

Salmonella enterica Serovar Typhimurium Exploits Inflammation to Compete with the Intestinal Microbiota

PubMed Central

Stecher, Bärbel; Westendorf, Astrid M; Barthel, Manja; Kremer, Marcus; Chaffron, Samuel; Macpherson, Andrew J; Buer, Jan; Parkhill, Julian; Dougan, Gordon; von Mering, Christian; Hardt, Wolf-Dietrich

2007-01-01

Most mucosal surfaces of the mammalian body are colonized by microbial communities (“microbiota”). A high density of commensal microbiota inhabits the intestine and shields from infection (“colonization resistance”). The virulence strategies allowing enteropathogenic bacteria to successfully compete with the microbiota and overcome colonization resistance are poorly understood. Here, we investigated manipulation of the intestinal microbiota by the enteropathogenic bacterium Salmonella enterica subspecies 1 serovar Typhimurium (S. Tm) in a mouse colitis model: we found that inflammatory host responses induced by S. Tm changed microbiota composition and suppressed its growth. In contrast to wild-type S. Tm, an avirulent invGsseD mutant failing to trigger colitis was outcompeted by the microbiota. This competitive defect was reverted if inflammation was provided concomitantly by mixed infection with wild-type S. Tm or in mice (IL10−/−, VILLIN-HACL4-CD8) with inflammatory bowel disease. Thus, inflammation is necessary and sufficient for overcoming colonization resistance. This reveals a new concept in infectious disease: in contrast to current thinking, inflammation is not always detrimental for the pathogen. Triggering the host's immune defence can shift the balance between the protective microbiota and the pathogen in favour of the pathogen. PMID:17760501

FimY Does Not Interfere with FimZ-FimW Interaction during Type 1 Fimbria Production by Salmonella enterica Serovar Typhimurium

PubMed Central

Zeiner, Sarah A.; Dwyer, Brett E.

2013-01-01

The production of type 1 fimbriae in Salmonella enterica serovar Typhimurium is controlled, in part, by three proteins, FimZ, FimY, and FimW. Amino acid sequence analysis indicates that FimZ belongs to the family of bacterial response regulators of two-component systems. In these studies, we have demonstrated that introducing a mutation mimicking phosphorylation of FimZ is necessary for activation of its target gene, fimA. In addition, the interaction of FimZ with FimW, a repressor of fimA expression, occurs only when FimZ is phosphorylated. Consequently, the negative regulatory effect of FimW is most likely due to downmodulation of the active FimZ protein. FimY does not appear to function as a response regulator, and its activity can be lost by mimicking the phosphorylation of FimY. Overproduction of FimY cannot alleviate the nonfimbriate phenotype in a FimZ mutant, whereas high levels of FimZ can overcome the nonfimbriate phenotype of a FimY mutant. It appears that FimY acts upstream of FimZ to activate fimA expression. PMID:24042120

Optimization of inactivated H5N9 highly pathogenic avian influenza vaccine and inactivated Salmonella enterica serovar Typhimurium vaccine with antigen dose and prime-boost regimen in domestic ducks.

PubMed

Yuk, Seong-Su; To, Eredene-Ochir; Kwon, Jung-Hoon; Noh, Jin-Yong; Hong, Woo-Tack; Jeong, Jei-Hyun; Gwon, Gyeong-Bin; Song, Chang-Seon

2017-09-01

Owing to the increase in the number of diseases affecting ducks and the demand for food safety by consumers, vaccination has become one of the factors that influence duck meat productivity. The highly pathogenic avian influenza (HPAI) virus is one of the most prevalent and causes one of the most lethal diseases in domestic ducks, and Salmonella enterica serovar Typhimurium is a food-borne pathogen persistent in the domestic duck population. To better understand the optimal usage of HPAI and S. enterica serovar Typhimurium vaccines, we aimed to determine antigen dose, oil and gel adjuvant usage with prime-boost regimen, and vaccination age, inducing the best immune response in ducks, without an effect on body weight gain. In the case of the inactivated H5N9 vaccine, a single dose of vaccine was inadequate to induce proper antibody titer when administered to day-old ducks, which necessitates boost vaccination. Administration of the oil-adjuvanted H5N9 vaccine administration in day-old and 2-week-old ducks resulted in a lower body weight at the time of slaughtering, compared to that of gel-adjuvanted H5N9 vaccine. However, gel-adjuvanted H5N9 vaccine failed to induce proper immune response to an extent recommend by OIE-World Organization for Animal Health. In the case of the Salmonella enterica serovar Typhimurium vaccine, a moderate or low dose of vaccine was appropriate for day-old ducks receiving the gel prime-oil boost vaccination. Single vaccination with oil adjuvants affects the mean body weight of 7-week-old ducks, suggesting that the gel adjuvant is more suitable for meat production. We expect that the use of adjuvants in a prime-boost regimen and at antigen doses set in this study will be helpful to maximize body weight in the case of domestic duck production at the actual farm site. © 2017 Poultry Science Association Inc.

A Nutrient-Tunable Bistable Switch Controls Motility in Salmonella enterica Serovar Typhimurium

PubMed Central

Koirala, Santosh; Mears, Patrick; Sim, Martin; Golding, Ido; Chemla, Yann R.; Aldridge, Phillip D.

2014-01-01

ABSTRACT Many bacteria are motile only when nutrients are scarce. In contrast, Salmonella enterica serovar Typhimurium is motile only when nutrients are plentiful, suggesting that this bacterium uses motility for purposes other than foraging, most likely for host colonization. In this study, we investigated how nutrients affect motility in S. enterica and found that they tune the fraction of motile cells. In particular, we observed coexisting populations of motile and nonmotile cells, with the distribution being determined by the concentration of nutrients in the growth medium. Interestingly, S. enterica responds not to a single nutrient but apparently to a complex mixture of them. Using a combination of experimentation and mathematical modeling, we investigated the mechanism governing this behavior and found that it results from two antagonizing regulatory proteins, FliZ and YdiV. We also found that a positive feedback loop involving the alternate sigma factor FliA is required, although its role appears solely to amplify FliZ expression. We further demonstrate that the response is bistable: that is, genetically identical cells can exhibit different phenotypes under identical growth conditions. Together, these results uncover a new facet of the regulation of the flagellar genes in S. enterica and further demonstrate how bacteria employ phenotypic diversity as a general mechanism for adapting to change in their environment. PMID:25161191

Influence of Environmental Factors and Human Activity on the Presence of Salmonella Serovars in a Marine Environment

PubMed Central

Martinez-Urtaza, Jaime; Saco, Montserrat; de Novoa, Jacobo; Perez-Piñeiro, Pelayo; Peiteado, Jesus; Lozano-Leon, Antonio; Garcia-Martin, Oscar

2004-01-01

The temporal and spatial distribution of Salmonella contamination in the coastal waters of Galicia (northwestern Spain) relative to contamination events with different environmental factors (temperature, wind, hours of sunlight, rainfall, and river flow) were investigated over a 4-year period. Salmonellae were isolated from 127 of 5,384 samples of molluscs and seawater (2.4%), and no significant differences (P < 0.05) between isolates obtained in different years were observed. The incidence of salmonellae was significantly higher in water column samples (2.9%) than in those taken from the marine benthos (0.7%). Of the 127 strains of Salmonella isolated, 20 different serovars were identified. Salmonella enterica serovar Senftenberg was the predominant serovar, being represented by 54 isolates (42.5%), followed by serovar Typhimurium (19 isolates [15%]) and serovar Agona (12 isolates [9.4%]). Serovar Senftenberg was detected at specific points on the coast and could not be related to any of the environmental parameters analyzed. All serovars except Salmonella serovar Senftenberg were found principally in the southern coastal areas close to the mouths of rivers, and their incidence was associated with high southwestern wind and rainfall. Using multiple logistic regression analysis models, the prevalence of salmonellae was best explained by environmental parameters on the day prior to sampling. Understanding this relationship may be useful for the control of molluscan shellfish harvests, with wind and rainfall serving as triggers for closure. PMID:15066800

Use of an attenuated live Salmonella Typhimurium vaccine on three breeding pig units: A longitudinal observational field study.

PubMed

Davies, R; Gosling, R J; Wales, A D; Smith, R P

2016-06-01

The study examined the effects of a licensed live Salmonella Typhimurium vaccine, administered to sows and gilts on three commercial pig units experiencing clinical salmonellosis associated with S. Typhimurium or its monophasic variant. After vaccination, clinical salmonellosis resolved and shedding of S. Typhimurium declined markedly and persistently on all breeding or breeding-finishing units, during the one- to two-year monitoring period. On two finishing units supplied in part by one of the vaccinated herds, pigs from the vaccinated herd were less likely to shed Salmonella than those from non-vaccinating herds, and Salmonella counts in faeces were also lower from the vaccine-linked animals. Non-Typhimurium Salmonella serovars were isolated typically in fewer than 10% of samples, and showed no clear temporal changes in frequency. Vaccination of dams alone with S. Typhimurium was associated with reduced shedding of closely-related serovars among all age groups in this commercial setting. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

ProP Is Required for the Survival of Desiccated Salmonella enterica Serovar Typhimurium Cells on a Stainless Steel Surface

PubMed Central

Finn, Sarah; Händler, Kristian; Condell, Orla; Colgan, Aoife; Cooney, Shane; McClure, Peter; Amézquita, Aléjandro; Hinton, Jay C. D.

2013-01-01

Consumers trust commercial food production to be safe, and it is important to strive to improve food safety at every level. Several outbreaks of food-borne disease have been caused by Salmonella strains associated with dried food. Currently we do not know the mechanisms used by Salmonella enterica serovar Typhimurium to survive in desiccated environments. The aim of this study was to discover the responses of S. Typhimurium ST4/74 at the transcriptional level to desiccation on a stainless steel surface and to subsequent rehydration. Bacterial cells were dried onto the same steel surfaces used during the production of dry foods, and RNA was recovered for transcriptomic analysis. Subsequently, dried cells were rehydrated and were again used for transcriptomic analysis. A total of 266 genes were differentially expressed under desiccation stress compared with a static broth culture. The osmoprotectant transporters proP, proU, and osmU (STM1491 to STM1494) were highly upregulated by drying. Deletion of any one of these transport systems resulted in a reduction in the long-term viability of S. Typhimurium on a stainless steel food contact surface. The proP gene was critical for survival; proP deletion mutants could not survive desiccation for long periods and were undetectable after 4 weeks. Following rehydration, 138 genes were differentially expressed, with upregulation observed for genes such as proP, proU, and the phosphate transport genes (pstACS). In time, this knowledge should prove valuable for understanding the underlying mechanisms involved in pathogen survival and should lead to improved methods for control to ensure the safety of intermediate- and low-moisture foods. PMID:23666329

Immune Reaction and Survivability of Salmonella Typhimurium and Salmonella Infantis after Infection of Primary Avian Macrophages

PubMed Central

Braukmann, Maria; Methner, Ulrich; Berndt, Angela

2015-01-01

Salmonella serovars are differentially able to infect chickens. The underlying causes are not yet fully understood. Aim of the present study was to elucidate the importance of Salmonella Pathogenicity Island 1 and 2 (SPI-1 and -2) for the virulence of two non-host-specific, but in-vivo differently invasive, Salmonella serovars in conjunction with the immune reaction of the host. Primary avian splenic macrophages were inoculated with Salmonella enterica sub-species enterica serovar (S.) Typhimurium and S. Infantis. The number and viability of intracellular bacteria and transcription of SPI-1 and -2 genes by the pathogens, as well as transcription of immune-related proteins, surface antigen expression and nitric oxide production by the macrophages, were compared at different times post inoculation. After infection, both of the Salmonella serovars were found inside the primary macrophages. Invasion-associated SPI-1 genes were significantly higher transcribed in S. Infantis- than S. Typhimurium-infected macrophages. The macrophages counteracted the S. Infantis and S. Typhimurium infection with elevated mRNA expression of inducible nitric oxide synthase (iNOS), interleukin (IL)-12, IL-18 and lipopolysaccharide-induced tumor necrosis factor alpha factor (LITAF) as well as with an increased synthesis of nitric oxide. Despite these host cell attacks, S. Typhimurium was better able than S. Infantis to survive within the macrophages and transcribed higher rates of the SPI-2 genes spiC, ssaV, sifA, and sseA. The results showed similar immune reactions of primary macrophages after infection with both of the Salmonella strains. The more rapid and stronger transcription of SPI-2-related genes by intracellular S. Typhimurium compared to S. Infantis might be responsible for its better survival in avian primary macrophages. PMID:25811871

The Early Innate Response of Chickens to Salmonella enterica Is Dependent on the Presence of O-Antigen but Not on Serovar Classification

PubMed Central

Varmuzova, Karolina; Matulova, Marta Elsheimer; Sebkova, Alena; Sekelova, Zuzana; Havlickova, Hana; Sisak, Frantisek; Babak, Vladimir; Rychlik, Ivan

2014-01-01

Salmonella vaccines used in poultry in the EU are based on attenuated strains of either Salmonella serovar Enteritidis or Typhimurium which results in a decrease in S. Enteritidis and S. Typhimurium but may allow other Salmonella serovars to fill an empty ecological niche. In this study we were therefore interested in the early interactions of chicken immune system with S. Infantis compared to S. Enteritidis and S. Typhimurium, and a role of O-antigen in these interactions. To reach this aim, we orally infected newly hatched chickens with 7 wild type strains of Salmonella serovars Enteritidis, Typhimurium and Infantis as well as with their rfaL mutants and characterized the early Salmonella-chicken interactions. Inflammation was characterized in the cecum 4 days post-infection by measuring expression of 43 different genes. All wild type strains stimulated a greater inflammatory response than any of the rfaL mutants. However, there were large differences in chicken responses to different wild type strains not reflecting their serovar classification. The initial interaction between newly-hatched chickens and Salmonella was found to be dependent on the presence of O-antigen but not on its structure, i.e. not on serovar classification. In addition, we observed that the expression of calbindin or aquaporin 8 in the cecum did not change if inflammatory gene expression remained within a 10 fold fluctuation, indicating the buffering capacity of the cecum, preserving normal gut functions even in the presence of minor inflammatory stimuli. PMID:24763249

Thermal Resistance and Gene Expression of both Desiccation-Adapted and Rehydrated Salmonella enterica Serovar Typhimurium Cells in Aged Broiler Litter

PubMed Central

Chen, Zhao

2017-01-01

ABSTRACT The objective of this study was to investigate the thermal resistance and gene expression of both desiccation-adapted and rehydrated Salmonella enterica serovar Typhimurium cells in aged broiler litter. S. Typhimurium was desiccation adapted in aged broiler litter with a 20% moisture content (water activity [aw], 0.81) for 1, 2, 3, 12, or 24 h at room temperature and then rehydrated for 3 h. As analyzed by quantitative real-time reverse transcriptase PCR (qRT-PCR), the rpoS, proV, dnaK, and grpE genes were upregulated (P < 0.05) under desiccation stress and could be induced after 1 h but in less than 2 h. Following rehydration, fold changes in the levels of these four genes became significantly lower (P < 0.05). The desiccation-adapted ΔrpoS mutant was less heat resistant at 75°C than was the desiccation-adapted wild type (P < 0.05), whereas there were no differences in heat resistance between desiccation-adapted mutants in two nonregulated genes (otsA and PagfD) and the desiccation-adapted wild type (P > 0.05). Survival characteristics of the desiccation-adapted ΔPagfD (rdar [red, dry, and rough] morphotype) and ΔagfD (saw [smooth and white] morphotype) mutants were similar (P > 0.05). Trehalose synthesis in the desiccation-adapted wild type was not induced compared to a nonadapted control (P > 0.05). Our results demonstrated the importance of the rpoS, proV, dnaK, and grpE genes in the desiccation survival of S. Typhimurium. By using an ΔrpoS mutant, we found that the rpoS gene was involved in the cross-protection of desiccation-adapted S. Typhimurium against high temperatures, while trehalose synthesis or rdar morphology did not play a significant role in this phenomenon. In summary, S. Typhimurium could respond rapidly to low-aw conditions in aged broiler litter while developing cross-protection against high temperatures, but this process could be reversed upon rehydration. IMPORTANCE Physical heat treatment is effective in eliminating human

Serovars, bacteriophage types and antimicrobial sensitivities associated with salmonellosis in dogs in the UK (1954-2012).

PubMed

Philbey, A W; Mather, H A; Gibbons, J F; Thompson, H; Taylor, D J; Coia, J E

2014-01-25

Serovars and bacteriophage (phage) types were determined for 442 isolates of Salmonella enterica from dogs in the UK submitted to the Scottish Salmonella Reference Laboratory from 1954 to 2012. The most frequent serovars were Salmonella Typhimurium (196 isolates; 44.3 per cent), Dublin (40 isolates; 9.0 per cent), Enteritidis (28 isolates; 6.3 per cent), Montevideo (19 isolates; 4.3 per cent), Virchow (10 isolates; 2.3 per cent), Heidelberg (8 isolates; 1.8 per cent) and Derby (8 isolates; 1.8 per cent), along with 55 other recognised serovars among 127 other isolates, and six incompletely classified isolates. Serovars were frequently represented by strains commonly associated with poultry, cattle or pigs and their products. Among 196 Salmonella Typhimurium isolates from dogs, the most frequent phage types (definitive types) were the multiple antimicrobial-resistant strains DT104 (62 isolates), DT204c (18 isolates) and DT193 (8 isolates), along with antimicrobial sensitive wild finch strains DT40 (13 isolates) and DT56 variant (8 isolates). Eleven of 28 isolates of Salmonella Enteritidis were phage type 4. S enterica was frequently recovered from faecal or intestinal samples of dogs with diarrhoea, although many dogs had concurrent infection with other enteric pathogens. Salmonella Dublin was recovered from the brain and/or cerebrospinal fluid of two dogs with meningoencephalitis. Salmonella Kedougou was isolated from the joint fluid of a dog with septic arthritis. Salmonella Typhimurium and Salmonella Dublin were each recovered from the vaginas of bitches that had aborted. Isolates of Salmonella Enteritidis phage types 1, 4 and 8, Salmonella Typhimurium DT104, Salmonella Dublin and Salmonella Indiana were isolated from clinically healthy dogs in households where the same strains were recovered from human beings with diarrhoea. The pattern ampicillin-chloramphenicol-spectinomycin-streptomycin-sulfamethoxazole-tetracycline (ACSpSSuT) was the most frequent resistance

Camel as a transboundary vector for emerging exotic Salmonella serovars.

PubMed

Ghoneim, Nahed H; Abdel-Moein, Khaled A; Zaher, Hala

2017-05-01

The current study was conducted to shed light on the role of imported camels as a transboundary vector for emerging exotic Salmonella serovars. Fecal samples were collected from 206 camels directly after slaughtering including 25 local camels and 181 imported ones as well as stool specimens were obtained from 50 slaughterhouse workers at the same abattoir. The obtained samples were cultured while Salmonella serovars were identified through Gram's stain films, biochemical tests and serotyping with antisera kit. Moreover, the obtained Salmonella serovars were examined by PCR for the presence of invA and stn genes. The overall prevalence of Salmonella serovars among the examined camels was 8.3%. Stn gene was detected in the vast majority of exotic strains (11/14) 78.6% including emerging serovars such as Salmonella Saintpaul, S. Chester, S. Typhimurium whereas only one isolate from local camels carried stn gene (1/3) 33.3%. On the other hand, none of the examined humans yielded positive result. Our findings highlight the potential role of imported camels as a transboundary vector for exotic emerging Salomenella serovars.

Serovar distribution, antimicrobial resistance profiles, and PFGE typing of Salmonella enterica strains isolated from 2007–2012 in Guangdong, China

PubMed Central

2014-01-01

Background Salmonella enterica includes the major serovars associated with human salmonellosis. In this study, 1764 clinical Salmonella enterica isolates from diarrhea outpatients were collected from fifteen cities in Guangdong province, China, between 2007 and 2012. These isolates represent all of the Salmonella isolates collected from the province during that period. Methods The isolates were characterized by serovar determination, antimicrobial susceptibility tests and PFGE fingerprint typing. Results The serovar distribution results demonstrated that Salmonella Typhimurium (n = 523, 29.65%) and Salmonella 4,5,12:i:- (n = 244, 13.83%) are the most common serovars causing infant salmonellosis, whereas Salmonella Enteritidis (n = 257, 14.57%) mainly causes human salmonellosis in adults. The serovar shift from Salmonella Enteritidis to Salmonella Typhimurium occurred in 2008. Antimicrobial susceptibility data showed a high burden of multidrug resistance (MDR) (n = 1128, 56.58%), and a 20%-30% increase in the number of isolates resistant to ciprofloxacin (n = 142, 8.05%) and third-generation cephalosporins (n = 88, 4.99%) from 2007–2012. Only 9.97% of isolates (n = 176) were fully susceptible to all agents tested. A high burden of MDR was observed in Salmonella Typhimurium and Salmonella 4,5,12:i:- for all age groups, and a reduced susceptibility to third-generation cephalosporins and quinolones occurred particularly in infants (≤6 years). The dominant PFGE patterns were JPXX01.GD0004, JEGX01.GD0006-7 and JNGX01.GD0006-7. ACSSuT was the predominant MDR profile in the Salmonella Typhimurium & 4,5,12:i:- complexes, while ASSuT-Nal and ASSu-Nal were the major MDR profiles in Salmonella Enteritidis. The predominant PFGE patterns of the Salmonella Typhimurium & 4,5,12:i:- complexes and Salmonella Stanley were most prevalent in infants (≤6 years). However, no obvious relationship was observed between these PFGE profiles and geographic

Detection of Salmonella typhimurium in retail chicken meat and chicken giblets.

PubMed

El-Aziz, Doaa M Abd

2013-09-01

To detect Salmonella typhimurium (S. typhimurium), one of the most frequently isolated serovars from food borne outbreaks throughout the world, in retail raw chicken meat and giblets. One hundred samples of retail raw chicken meat and giblets (Liver, heart and gizzard) which were collected from Assiut city markets for detection of the organism and by using Duplex PCR amplification of DNA using rfbJ and fliC genes. S. typhimurium was detected at rate of 44%, 40% and 48% in chicken meat, liver and heart, respectively, but not detected in gizzard. The results showed high incidence of S. typhimurium in the examined samples and greater emphasis should be applied on prevention and control of contamination during processing for reducing food-borne risks to consumers.

The Vi Capsular Polysaccharide Enables Salmonella enterica Serovar Typhi to Evade Microbe-Guided Neutrophil Chemotaxis

PubMed Central

Wangdi, Tamding; Lee, Cheng-Yuk; Spees, Alanna M.; Yu, Chenzhou; Kingsbury, Dawn D.; Winter, Sebastian E.; Hastey, Christine J.; Wilson, R. Paul

2014-01-01

Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever, a disseminated infection, while the closely related pathogen S. enterica serovar Typhimurium (S. Typhimurium) is associated with a localized gastroenteritis in humans. Here we investigated whether both pathogens differ in the chemotactic response they induce in neutrophils using a single-cell experimental approach. Surprisingly, neutrophils extended chemotactic pseudopodia toward Escherichia coli and S. Typhimurium, but not toward S. Typhi. Bacterial-guided chemotaxis was dependent on the presence of complement component 5a (C5a) and C5a receptor (C5aR). Deletion of S. Typhi capsule biosynthesis genes markedly enhanced the chemotactic response of neutrophils in vitro. Furthermore, deletion of capsule biosynthesis genes heightened the association of S. Typhi with neutrophils in vivo through a C5aR-dependent mechanism. Collectively, these data suggest that expression of the virulence-associated (Vi) capsular polysaccharide of S. Typhi obstructs bacterial-guided neutrophil chemotaxis. PMID:25101794

Analysis of Salmonella enterica Serovar Typhimurium Variable-Number Tandem-Repeat Data for Public Health Investigation Based on Measured Mutation Rates and Whole-Genome Sequence Comparisons

PubMed Central

Dimovski, Karolina; Cao, Hanwei; Wijburg, Odilia L. C.; Strugnell, Richard A.; Mantena, Radha K.; Whipp, Margaret; Hogg, Geoff

2014-01-01

Variable-number tandem repeats (VNTRs) mutate rapidly and can be useful markers for genotyping. While multilocus VNTR analysis (MLVA) is increasingly used in the detection and investigation of food-borne outbreaks caused by Salmonella enterica serovar Typhimurium (S. Typhimurium) and other bacterial pathogens, MLVA data analysis usually relies on simple clustering approaches that may lead to incorrect interpretations. Here, we estimated the rates of copy number change at each of the five loci commonly used for S. Typhimurium MLVA, during in vitro and in vivo passage. We found that loci STTR5, STTR6, and STTR10 changed during passage but STTR3 and STTR9 did not. Relative rates of change were consistent across in vitro and in vivo growth and could be accurately estimated from diversity measures of natural variation observed during large outbreaks. Using a set of 203 isolates from a series of linked outbreaks and whole-genome sequencing of 12 representative isolates, we assessed the accuracy and utility of several alternative methods for analyzing and interpreting S. Typhimurium MLVA data. We show that eBURST analysis was accurate and informative. For construction of MLVA-based trees, a novel distance metric, based on the geometric model of VNTR evolution coupled with locus-specific weights, performed better than the commonly used simple or categorical distance metrics. The data suggest that, for the purpose of identifying potential transmission clusters for further investigation, isolates whose profiles differ at one of the rapidly changing STTR5, STTR6, and STTR10 loci should be collapsed into the same cluster. PMID:24957617

Global monitoring of Salmonella serovar distribution from the World Health Organization Global Foodborne Infections Network Country Data Bank: results of quality assured laboratories from 2001 to 2007.

PubMed

Hendriksen, Rene S; Vieira, Antonio R; Karlsmose, Susanne; Lo Fo Wong, Danilo M A; Jensen, Arne B; Wegener, Henrik C; Aarestrup, Frank M

2011-08-01

Salmonella enterica is commonly acquired from contaminated food and is an important cause of illness worldwide. Interventions are needed to control Salmonella; subtyping Salmonella by serotyping is useful for targeting such interventions. We, therefore, analyzed the global distribution of the 15 most frequently identified serovars of Salmonella isolated from humans from 2001 to 2007 in laboratories from 37 countries that participated in World Health Organization Global Foodborne Infections Network and demonstrated serotyping proficiency in the Global Foodborne Infections Network External Quality Assurance System. In all regions throughout the study period, with the exception of the Oceania and North American regions, Salmonella serovars Enteritidis and Typhimurium ranked as the most common and second most common serovar, respectively. In the North American and Oceania (Australia and New Zealand) regions, Salmonella serovar Typhimurium was the most common serovar reported, and Salmonella serovar Enteritidis was the second most common serovar. During the study period, the proportion of Salmonella isolates reported from humans that were Salmonella serovar Enteritidis was 43.5% (range: 40.6% [2007] to 44.9% [2003]), and Salmonella serovar Typhimurium was 17.1% (range: 15% [2007] to 18.9% [2001]). Salmonella serovars Newport (mainly observed in Latin and North American and European countries), Infantis (dominating in all regions), Virchow (mainly observed in Asian, European, and Oceanic countries), Hadar (profound in European countries), and Agona (intense in Latin and North American and European countries) were also frequently isolated with an overall proportion of 3.5%, 1.8%, 1.5%, 1.5%, and 0.8%, respectively. There were large differences in the most commonly isolated serovars between regions, but lesser differences between countries within the same region. The results also highlight the complexity of the global epidemiology of Salmonella and the need and importance

Prevalence, Virulence Genes and Antimicrobial Resistance Profiles of Salmonella Serovars from Retail Beef in Selangor, Malaysia

PubMed Central

Thung, Tze Y.; Radu, Son; Mahyudin, Nor A.; Rukayadi, Yaya; Zakaria, Zunita; Mazlan, Nurzafirah; Tan, Boon H.; Lee, Epeng; Yeoh, Soo L.; Chin, Yih Z.; Tan, Chia W.; Kuan, Chee H.; Basri, Dayang F.; Wan Mohamed Radzi, Che W. J.

2018-01-01

The aim of the present study was to investigate the prevalence of Salmonella spp., Salmonella Enteritidis and Salmonella Typhimurium in retail beef from different retail markets of Selangor area, as well as, to assess their pathogenic potential and antimicrobial resistance. A total of 240 retail beef meat samples (chuck = 60; rib = 60; round = 60; sirloin = 60) were randomly collected. The multiplex polymerase chain reaction (mPCR) in combination with the most probable number (MPN) method was employed to detect Salmonella spp., S. Enteritidis and S. Typhimurium in the meat samples. The prevalence of Salmonella spp., S. Enteritidis and S. Typhimurium in 240 beef meat samples were 7.50, 1.25, and 0.83%, respectively. The microbial loads of total Salmonella was found in the range of <3 to 15 MPN/g. Eight different serovars of Salmonella were identified among the 23 isolates, and S. Agona was the predominant serovar (26.09%). Interestingly, all the Salmonella isolates were resistant to penicillin, erythromycin and vancomycin, but the sensitivity was observed for tetracycline, gentamicin and amoxicillin/clavulanic acid. All 23 isolates were resistant to at least three antibiotics. Two S. Typhimurium isolates (8.70%) exhibited the highest multiple antibiotic resistance (MAR) index value of 0.56 which shown resistance to nine antibiotics. PCR analysis of virulence genes showed that all Salmonella isolates (100%) were positive for the invA gene. Meanwhile, pefA was only identified in S. Enteritidis and S. Typhimurium. The findings in this study indicate that retail beef products tested were widely contaminated with multi-drug resistant (MDR) Salmonella and various virulence genes are present among the isolated Salmonella serovars. PMID:29379488

Prevalence, Virulence Genes and Antimicrobial Resistance Profiles of Salmonella Serovars from Retail Beef in Selangor, Malaysia.

PubMed

Thung, Tze Y; Radu, Son; Mahyudin, Nor A; Rukayadi, Yaya; Zakaria, Zunita; Mazlan, Nurzafirah; Tan, Boon H; Lee, Epeng; Yeoh, Soo L; Chin, Yih Z; Tan, Chia W; Kuan, Chee H; Basri, Dayang F; Wan Mohamed Radzi, Che W J

2017-01-01

The aim of the present study was to investigate the prevalence of Salmonella spp., Salmonella Enteritidis and Salmonella Typhimurium in retail beef from different retail markets of Selangor area, as well as, to assess their pathogenic potential and antimicrobial resistance. A total of 240 retail beef meat samples (chuck = 60; rib = 60; round = 60; sirloin = 60) were randomly collected. The multiplex polymerase chain reaction (mPCR) in combination with the most probable number (MPN) method was employed to detect Salmonella spp., S . Enteritidis and S . Typhimurium in the meat samples. The prevalence of Salmonella spp., S . Enteritidis and S . Typhimurium in 240 beef meat samples were 7.50, 1.25, and 0.83%, respectively. The microbial loads of total Salmonella was found in the range of <3 to 15 MPN/g. Eight different serovars of Salmonella were identified among the 23 isolates, and S . Agona was the predominant serovar (26.09%). Interestingly, all the Salmonella isolates were resistant to penicillin, erythromycin and vancomycin, but the sensitivity was observed for tetracycline, gentamicin and amoxicillin/clavulanic acid. All 23 isolates were resistant to at least three antibiotics. Two S . Typhimurium isolates (8.70%) exhibited the highest multiple antibiotic resistance (MAR) index value of 0.56 which shown resistance to nine antibiotics. PCR analysis of virulence genes showed that all Salmonella isolates (100%) were positive for the invA gene. Meanwhile, pefA was only identified in S . Enteritidis and S . Typhimurium. The findings in this study indicate that retail beef products tested were widely contaminated with multi-drug resistant (MDR) Salmonella and various virulence genes are present among the isolated Salmonella serovars.

An enteric pathogen Salmonella enterica serovar Typhimurium suppresses tumor growth by downregulating CD44high and CD4T regulatory (Treg) cell expression in mice: the critical role of lipopolysaccharide and Braun lipoprotein in modulating tumor growth.

PubMed

Liu, T; Chopra, A K

2010-02-01

An antitumor activity associated with several bacterial pathogens, including Salmonella enterica serovar Typhimurium, has been reported; however, the underlying immunological mechanism(s) that lead to an antitumor effect are currently unclear. Furthermore, such pathogens cannot be used to suppress tumor growth because of their potential for causing sepsis. Recently, we reported the characterization of S. Typhimurium isogenic mutants from which Braun lipoprotein genes (lppA and B) and the multicopy repressor of high temperature requirement (msbB) gene were deleted. In a mouse infection model, two mutants, namely, lppB/msbB and lppAB/msbB, minimally induced proinflammatory cytokine production at high doses and were nonlethal to animals. We showed that immunization of mice with these mutants, followed by challenge with the wild-type S. Typhimurium, could significantly suppress tumor growth, as evidenced by an 88% regression in tumor size in lppB/msbB mutant-immunized animals over a 24-day period. However, the lppAB/msbB mutant alone was not effective in modulating tumor growth in mice, although the lppB/msbB mutant alone caused marginal regression in tumor size. Importantly, we showed that CD44(+) cells grew much faster than CD44(-) cells from human liver tumors in mice, leading us to examine the possibility that S. Typhimurium might downregulate CD44 in tumors and splenocytes of mice. Consequently, we found in S. Typhimurium-infected mice that tumor size regression could indeed be related to the downregulation of CD44(high) and CD4(+)CD25(+) T(reg) cells. Importantly, the role of lipopolysaccharide and Braun lipoprotein was critical in S. Typhimurium-induced antitumor immune responses. Taken together, we have defined new immune mechanisms leading to tumor suppression in mice by S. Typhimurium.

Evidence of metabolic switching and implications for food safety from the phenome(s) of Salmonella enterica serovar Typhimurium DT104 cultured at selected points across the pork production food chain.

PubMed

Martins, Marta; McCusker, Matthew P; McCabe, Evonne M; O'Leary, Denis; Duffy, Geraldine; Fanning, Séamus

2013-09-01

Salmonella enterica serovar Typhimurium DT104 is a recognized food-borne pathogen that displays a multidrug-resistant phenotype and that is associated with systemic infections. At one extreme of the food chain, this bacterium can infect humans, limiting the treatment options available and thereby contributing to increased morbidity and mortality. Although the antibiotic resistance profile is well defined, little is known about other phenotypes that may be expressed by this pathogen at key points across the pork production food chain. In this study, 172 Salmonella enterica serovar Typhimurium DT104/DT104b isolated from an extensive "farm-to-fork" surveillance study, focusing on the pork food chain, were characterized in detail. Isolates were cultured from environmental, processing, retail, and clinical sources, and the study focused on phenotypes that may have contributed to persistence/survival in these different niches. Molecular subtypes, along with antibiotic resistance profiles, tolerance to biocides, motility, and biofilm formation, were determined. As a basis for human infection, acid survival and the ability to utilize a range of energy sources and to adhere to and/or invade Caco-2 cells were also studied. Comparative alterations to biocide tolerance were observed in isolates from retail. l-Tartaric acid and d-mannose-1-phosphate induced the formation of biofilms in a preselected subset of strains, independent of their origin. All clinical isolates were motile and demonstrated an enhanced ability to survive in acidic conditions. Our data report on a diverse phenotype, expressed by S. Typhimurium isolates cultured from the pork production food chain. Extending our understanding of the means by which this pathogen adapts to environmental niches along the "farm-to-fork" continuum will facilitate the protection of vulnerable consumers through targeted improvements in food safety measures.

Evidence of Metabolic Switching and Implications for Food Safety from the Phenome(s) of Salmonella enterica Serovar Typhimurium DT104 Cultured at Selected Points across the Pork Production Food Chain

PubMed Central

Martins, Marta; McCusker, Matthew P.; McCabe, Evonne M.; O'Leary, Denis; Duffy, Geraldine

2013-01-01

Salmonella enterica serovar Typhimurium DT104 is a recognized food-borne pathogen that displays a multidrug-resistant phenotype and that is associated with systemic infections. At one extreme of the food chain, this bacterium can infect humans, limiting the treatment options available and thereby contributing to increased morbidity and mortality. Although the antibiotic resistance profile is well defined, little is known about other phenotypes that may be expressed by this pathogen at key points across the pork production food chain. In this study, 172 Salmonella enterica serovar Typhimurium DT104/DT104b isolated from an extensive “farm-to-fork” surveillance study, focusing on the pork food chain, were characterized in detail. Isolates were cultured from environmental, processing, retail, and clinical sources, and the study focused on phenotypes that may have contributed to persistence/survival in these different niches. Molecular subtypes, along with antibiotic resistance profiles, tolerance to biocides, motility, and biofilm formation, were determined. As a basis for human infection, acid survival and the ability to utilize a range of energy sources and to adhere to and/or invade Caco-2 cells were also studied. Comparative alterations to biocide tolerance were observed in isolates from retail. l-Tartaric acid and d-mannose-1-phosphate induced the formation of biofilms in a preselected subset of strains, independent of their origin. All clinical isolates were motile and demonstrated an enhanced ability to survive in acidic conditions. Our data report on a diverse phenotype, expressed by S. Typhimurium isolates cultured from the pork production food chain. Extending our understanding of the means by which this pathogen adapts to environmental niches along the “farm-to-fork” continuum will facilitate the protection of vulnerable consumers through targeted improvements in food safety measures. PMID:23770904

Detection of Salmonella typhimurium in retail chicken meat and chicken giblets

PubMed Central

El-Aziz, Doaa M Abd

2013-01-01

Objective To detect Salmonella typhimurium (S. typhimurium), one of the most frequently isolated serovars from food borne outbreaks throughout the world, in retail raw chicken meat and giblets. Methods One hundred samples of retail raw chicken meat and giblets (Liver, heart and gizzard) which were collected from Assiut city markets for detection of the organism and by using Duplex PCR amplification of DNA using rfbJ and fliC genes. Results S. typhimurium was detected at rate of 44%, 40% and 48% in chicken meat, liver and heart, respectively, but not detected in gizzard. Conclusions The results showed high incidence of S. typhimurium in the examined samples and greater emphasis should be applied on prevention and control of contamination during processing for reducing food-borne risks to consumers. PMID:23998006

Dietary rice bran promotes resistance to Salmonella enterica serovar Typhimurium colonization in mice.

PubMed

Kumar, Ajay; Henderson, Angela; Forster, Genevieve M; Goodyear, Andrew W; Weir, Tiffany L; Leach, Jan E; Dow, Steven W; Ryan, Elizabeth P

2012-07-04

Dietary rice bran consists of many bioactive components with disease fighting properties; including the capacity to modulate the gut microbiota. Studies point to the important roles of the gut microbiota and the mucosal epithelium in the establishment of protection against enteric pathogens, such as Salmonella. The ability of rice bran to reduce the susceptibility of mice to a Salmonella infection has not been previously investigated. Therefore, we hypothesized that the incorporation of rice bran into the diet would inhibit the colonization of Salmonella in mice through the induction of protective mucosal responses. Mice were fed diets containing 0%, 10% and 20% rice bran for one week prior to being orally infected with Salmonella enterica serovar Typhimurium. We found that mice consuming the 10 and 20% rice bran diets exhibited a reduction in Salmonella fecal shedding for up to nine days post-infection as compared to control diet fed animals (p < 0.05). In addition, we observed decreased concentrations of the pro-inflammatory cytokines, TNF-alpha, IFN-gamma, and IL-12 (p < 0.05) as well as increased colonization of native Lactobacillus spp. in rice bran fed mice (p < 0.05). Furthermore, in vitro experiments revealed the ability of rice bran extracts to reduce Salmonella entry into mouse small intestinal epithelial cells. Increasing rice bran consumption represents a novel dietary means for reducing susceptibility to enteric infection with Salmonella and potentially via induction of native Lactobacillus spp.

Dietary rice bran promotes resistance to Salmonella enterica serovar Typhimurium colonization in mice

PubMed Central

2012-01-01

Background Dietary rice bran consists of many bioactive components with disease fighting properties; including the capacity to modulate the gut microbiota. Studies point to the important roles of the gut microbiota and the mucosal epithelium in the establishment of protection against enteric pathogens, such as Salmonella. The ability of rice bran to reduce the susceptibility of mice to a Salmonella infection has not been previously investigated. Therefore, we hypothesized that the incorporation of rice bran into the diet would inhibit the colonization of Salmonella in mice through the induction of protective mucosal responses. Results Mice were fed diets containing 0%, 10% and 20% rice bran for one week prior to being orally infected with Salmonella enterica serovar Typhimurium. We found that mice consuming the 10 and 20% rice bran diets exhibited a reduction in Salmonella fecal shedding for up to nine days post-infection as compared to control diet fed animals (p < 0.05). In addition, we observed decreased concentrations of the pro-inflammatory cytokines, TNF-alpha, IFN-gamma, and IL-12 (p < 0.05) as well as increased colonization of native Lactobacillus spp. in rice bran fed mice (p < 0.05). Furthermore, in vitro experiments revealed the ability of rice bran extracts to reduce Salmonella entry into mouse small intestinal epithelial cells. Conclusions Increasing rice bran consumption represents a novel dietary means for reducing susceptibility to enteric infection with Salmonella and potentially via induction of native Lactobacillus spp. PMID:22583915

Identification and Characterization of Outer Membrane Vesicle-Associated Proteins in Salmonella enterica Serovar Typhimurium

PubMed Central

Bai, Jaewoo; Kim, Seul I; Ryu, Sangryeol

2014-01-01

Salmonella enterica serovar Typhimurium is a primary cause of enteric diseases and has acquired a variety of virulence factors during its evolution into a pathogen. Secreted virulence factors interact with commensal flora and host cells and enable Salmonella to survive and thrive in hostile environments. Outer membrane vesicles (OMVs) released from many Gram-negative bacteria function as a mechanism for the secretion of complex mixtures, including virulence factors. We performed a proteomic analysis of OMVs that were isolated under standard laboratory and acidic minimal medium conditions and identified 14 OMV-associated proteins that were observed in the OMV fraction isolated only under the acidic minimal medium conditions, which reproduced the nutrient-deficient intracellular milieu. The inferred roles of these 14 proteins were diverse, including transporter, enzyme, and transcriptional regulator. The absence of these proteins influenced Salmonella survival inside murine macrophages. Eleven of these proteins were predicted to possess secretion signal sequences at their N termini, and three (HupA, GlnH, and PhoN) of the proteins were found to be translocated into the cytoplasm of host cells. The comparative proteomic profiling of OMVs performed in this study revealed different protein compositions in the OMVs isolated under the two different conditions, which indicates that the OMV cargo depends on the growth conditions and provides a deeper insight into how Salmonella utilizes OMVs to adapt to environmental changes. PMID:24935973

Evaluation of Molecular Methods for Identification of Salmonella Serovars

PubMed Central

Gurnik, Simone; Ahmad, Aaminah; Blimkie, Travis; Murphy, Stephanie A.; Kropinski, Andrew M.; Nash, John H. E.

2016-01-01

Classification by serotyping is the essential first step in the characterization of Salmonella isolates and is important for surveillance, source tracking, and outbreak detection. To improve detection and reduce the burden of salmonellosis, several rapid and high-throughput molecular Salmonella serotyping methods have been developed. The aim of this study was to compare three commercial kits, Salm SeroGen (Salm Sero-Genotyping AS-1 kit), Check&Trace (Check-Points), and xMAP (xMAP Salmonella serotyping assay), to the Salmonella genoserotyping array (SGSA) developed by our laboratory. They were assessed using a panel of 321 isolates that represent commonly reported serovars from human and nonhuman sources globally. The four methods correctly identified 73.8% to 94.7% of the isolates tested. The methods correctly identified 85% and 98% of the clinically important Salmonella serovars Enteritidis and Typhimurium, respectively. The methods correctly identified 75% to 100% of the nontyphoidal, broad host range Salmonella serovars, including Heidelberg, Hadar, Infantis, Kentucky, Montevideo, Newport, and Virchow. The sensitivity and specificity of Salmonella serovars Typhimurium and Enteritidis ranged from 85% to 100% and 99% to 100%, respectively. It is anticipated that whole-genome sequencing will replace serotyping in public health laboratories in the future. However, at present, it is approximately three times more expensive than molecular methods. Until consistent standards and methodologies are deployed for whole-genome sequencing, data analysis and interlaboratory comparability remain a challenge. The use of molecular serotyping will provide a valuable high-throughput alternative to traditional serotyping. This comprehensive analysis provides a detailed comparison of commercial kits available for the molecular serotyping of Salmonella. PMID:27194688

Fluorescence-based thermal shift data on multidrug regulator AcrR from Salmonella enterica subsp. entrica serovar Typhimurium str. LT2.

PubMed

Manjasetty, Babu A; Halavaty, Andrei S; Luan, Chi-Hao; Osipiuk, Jerzy; Mulligan, Rory; Kwon, Keehwan; Anderson, Wayne F; Joachimiak, Andrzej

2016-06-01

The fluorescence-based thermal shift (FTS) data presented here include Table S1 and Fig. S1, and are supplemental to our original research article describing detailed structural, FTS, and fluorescence polarization analyses of the Salmonella enterica subsp. entrica serovar Typhimurium str. LT2 multidrug transcriptional regulator AcrR (StAcrR) (doi:10.1016/j.jsb.2016.01.008) (Manjasetty et al., 2015 [1]). Table S1 contains chemical formulas, a Chemical Abstracts Service (CAS) Registry Number (CAS no.), FTS rank (a ligand with the highest rank) has the largest difference in the melting temperature (ΔT m), and uses as drug molecules against various pathological conditions of sixteen small-molecule ligands that increase thermal stability of StAcrR. Thermal stability of human enolase 1, a negative control protein, was not affected in the presence of various concentrations of the top six StAcrR binders (Fig. S1).

Adhesion and growth inhibitory effect of chicken egg yolk antibody (IgY) on Salmonella enterica serovars Enteritidis and Typhimurium in vitro.

PubMed

Chalghoumi, Raja; Théwis, André; Beckers, Yves; Marcq, Christopher; Portetelle, Daniel; Schneider, Yves-Jacques

2009-06-01

The protective effects of powder preparation of egg yolk immunoglobulin Y (IgY), specific to Salmonella Enteritidis and Salmonella Typhimurium outer membrane proteins (OMP), against these two Salmonella sp. serovars were investigated in vitro in two different assays: adhesion-prevention and growth-inhibition. The adhesion-prevention assay was conducted using polarized monolayers of the human intestinal epithelial Caco-2 cell line. First, the conditions of Salmonella adherence to Caco-2 cells were optimized, and interferences of bacteria with the transepithelial electrical resistance (TER) of fully differentiated Caco-2 cell monolayers and the lactate dehydrogenase release upon exposure of the cells to Salmonella were evaluated. Both Salmonella sp. serovars were able to adhere to Caco-2 cells and decreased TER. Results from the adhesion-prevention assay demonstrated that specific IgY reduced the decrease in TER of the infected Caco-2 cell monolayers and blocked the Salmonella sp. adhesion in a concentration-dependent manner (p < 0.05). Nonspecific IgY also exhibited an inhibitory effect on these two parameters, but to a lesser extent than that of the specific IgY (p < 0.05). The protective effect of nonspecific IgY could be attributed to the low-density lipoprotein component of the water-soluble fraction of egg yolks that may not have been eliminated during ultrafiltration. The growth-inhibition assay revealed that specific IgY had an inhibitory effect on the bacterial growth, markedly during the late exponential phase, whereas nonspecific IgY failed to do so. Taken together, these results suggest that the in vitro growth inhibitory effect of specific IgY on Salmonella spp. resulted from the specific binding activity of these IgY to Salmonella sp. OMP. Passive immunization with Salmonella sp. OMP-specific IgY could thus be useful to prevent Salmonella colonization in broiler chickens and the subsequent carcass contamination during processing.

rpoS-Regulated Core Genes Involved in the Competitive Fitness of Salmonella enterica Serovar Kentucky in the Intestines of Chickens

PubMed Central

Cheng, Ying; Pedroso, Adriana Ayres; Porwollik, Steffen; McClelland, Michael; Lee, Margie D.; Kwan, Tiffany; Zamperini, Katherine; Soni, Vivek; Sellers, Holly S.; Russell, Scott M.

2014-01-01

Salmonella enterica serovar Kentucky has become the most frequently isolated serovar from poultry in the United States over the past decade. Despite its prevalence in poultry, it causes few human illnesses in the United States. The dominance of S. Kentucky in poultry does not appear to be due to single introduction of a clonal strain, and its reduced virulence appears to correlate with the absence of virulence genes grvA, sseI, sopE, and sodC1. S. Kentucky's prevalence in poultry is possibly attributable to its metabolic adaptation to the chicken cecum. While there were no difference in the growth rate of S. Kentucky and S. Typhimurium grown microaerophilically in cecal contents, S. Kentucky persisted longer when chickens were coinfected with S. Typhimurium. The in vivo advantage that S. Kentucky has over S. Typhimurium appears to be due to differential regulation of core Salmonella genes via the stationary-phase sigma factor rpoS. Microarray analysis of Salmonella grown in cecal contents in vitro identified several metabolic genes and motility and adherence genes that are differentially activated in S. Kentucky. The contributions of four of these operons (mgl, prp, nar, and csg) to Salmonella colonization in chickens were assessed. Deletion of mgl and csg reduced S. Kentucky persistence in competition studies in chickens infected with wild-type or mutant strains. Subtle mutations affecting differential regulation of core Salmonella genes appear to be important in Salmonella's adaptation to its animal host and especially for S. Kentucky's emergence as the dominant serovar in poultry. PMID:25362062

Influence of RpoS, cAMP-receptor protein, and ppGpp on expression of the opgGH operon and osmoregulated periplasmic glucan content of Salmonella enterica serovar Typhimurium.

PubMed

Costa, Cristina S; Pizarro, Ramón A; Antón, Dora N

2009-11-01

A transcriptional fusion (opgG1::MudJ) to the opgGH operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) LT2, isolated by resistance to mecillinam, was used to study the influence of global regulators RpoS, ppGpp, and cAMP/cAMP-receptor protein (CRP) on expression of the opgGH operon and osmoregulated periplasmic glucan (OPG) content. Neither high growth medium osmolarity nor absence of ppGpp or CRP had important effects on opgG1::MudJ expression in exponential cultures. However, under the same conditions, OPG content was strongly decreased by high osmolarity or cAMP/CRP defectiveness, and reduced to a half by lack of ppGpp. In stationary cultures, high osmolarity as well as CRP loss caused significant descents in opgG1::MudJ expression that were compensated by inactivation of RpoS sigma factor. No effect of RpoS inactivation on OPG content was observed. It is concluded that opgGH expression in S. Typhimurium is only slightly affected by high osmolarity, but is inversely modulated by RpoS level. On the other hand, osmolarity and the cAMP/CRP global regulatory system appear to control OPG content, either directly or indirectly, mainly at the post-transcriptional level.

Revival of an old problem: an increase in Salmonella enterica serovar Typhimurium definitive phage type 8 infections in 2010 in England and Northern Ireland linked to duck eggs.

PubMed

Noble, D J; Lane, C; Little, C L; Davies, R; De Pinna, E; Larkin, L; Morgan, D

2012-01-01

Salmonella enterica serovar Typhimurium definitive phage type (DT) 8 is uncommon in humans in the UK. In July 2010, the Health Protection Agency reported an excess isolation rate of pan-susceptible S. Typhimurium DT8 in England and Northern Ireland. By the end of October, this amounted to 81 laboratory-confirmed human cases for all regions of England and Northern Ireland in 2010, an increase of 26% and 41% on 2009 and 2008, respectively. Descriptive epidemiological investigation found a strong association with infection and consumption of duck eggs. Duck eggs contaminated with S. Typhimurium DT8 were collected from a patient's home and also at farms in the duck-egg supply chain. Although duck eggs form a small part of total UK eggs sales, there has been significant growth in sales in recent years. This is the first known outbreak of salmonellosis linked to duck eggs in the UK since 1949 and highlighted the impact of a changing food source and market on the re-emergence of salmonellosis linked to duck eggs. Control measures by the duck-egg industry should be improved along with a continued need to remind the public and commercial caterers of the potential high risks of contracting salmonellosis from duck eggs.

Phage typing or CRISPR typing for epidemiological surveillance of Salmonella Typhimurium?

PubMed

Mohammed, Manal

2017-11-07

Salmonella Typhimurium is the most dominant Salmonella serovar around the world. It is associated with foodborne gastroenteritis outbreaks but has recently been associated with invasive illness and deaths. Characterization of S. Typhimurium is therefore very crucial for epidemiological surveillance. Phage typing has been used for decades for subtyping of S. Typhimurium to determine the epidemiological relation among isolates. Recent studies however have suggested that high throughput clustered regular interspaced short palindromic repeats (CRISPR) typing has the potential to replace phage typing. This study aimed to determine the efficacy of high-throughput CRISPR typing over conventional phage typing in epidemiological surveillance and outbreak investigation of S. Typhimurium. In silico analysis of whole genome sequences (WGS) of well-documented phage types of S. Typhimurium reveals the presence of different CRISPR type among strains belong to the same phage type. Furthermore, different phage types of S. Typhimurium share identical CRISPR type. Interestingly, identical spacers were detected among outbreak and non-outbreak associated DT8 strains of S. Typhimurium. Therefore, CRISPR typing is not useful for the epidemiological surveillance and outbreak investigation of S. Typhimurium and phage typing, until it is replaced by WGS, is still the gold standard method for epidemiological surveillance of S. Typhimurium.

Immune protection of chickens conferred by a vaccine consisting of attenuated strains of Salmonella Enteritidis, Typhimurium and Infantis.

PubMed

Varmuzova, Karolina; Faldynova, Marcela; Elsheimer-Matulova, Marta; Sebkova, Alena; Polansky, Ondrej; Havlickova, Hana; Sisak, Frantisek; Rychlik, Ivan

2016-10-15

The colonization of poultry with different Salmonella enterica serovars poses an issue throughout the world. In this study we therefore tested the efficacy of a vaccine consisting of attenuated strains of Salmonella enterica serovars Enteritidis, Typhimurium and Infantis against challenge with the same serovars and with S. Agona, Dublin and Hadar. We tested oral and aerosol administration of the vaccine, with or without co-administration of cecal microbiota from adult hens. The protective effect was determined by bacterial counts of the challenge strains up to week 18 of life and by characterizing the immune response using real-time PCR specific for 16 different genes. We have shown that a vaccine consisting of attenuated S. Enteritidis, S. Typhimurium and S. Infantis protected chickens against challenge with the wild type strains of the same serovars and partially protected chickens also against challenge with isolates belonging to serovars Dublin or Hadar. Aerosol vaccination was more effective at inducing systemic immunity whilst oral vaccination stimulated a local immune response in the gut. Co-administration of cecal microbiota increased the protectiveness in the intestinal tract but slightly decreased the systemic immune response. Adjusting the vaccine composition and changing the administration route therefore affects vaccine efficacy.

Global Screening of Salmonella enterica Serovar Typhimurium Genes for Desiccation Survival

PubMed Central

Mandal, Rabindra K.; Kwon, Young M.

2017-01-01

Salmonella spp., one of the most common foodborne bacterial pathogens, has the ability to survive under desiccation conditions in foods and food processing facilities for years. This raises the concerns of Salmonella infection in humans associated with low water activity foods. Salmonella responds to desiccation stress via complex pathways involving immediate physiological actions as well as coordinated genetic responses. However, the exact mechanisms of Salmonella to resist desiccation stress remain to be fully elucidated. In this study, we screened a genome-saturating transposon (Tn5) library of Salmonella Typhimurium (S. Typhimurium) 14028s under the in vitro desiccation stress using transposon sequencing (Tn-seq). We identified 61 genes and 6 intergenic regions required to overcome desiccation stress. Salmonella desiccation resistance genes were mostly related to energy production and conversion; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; regulation of biological process; DNA metabolic process; ABC transporters; and two component system. More than 20% of the Salmonella desiccation resistance genes encode either putative or hypothetical proteins. Phenotypic evaluation of 12 single gene knockout mutants showed 3 mutants (atpH, atpG, and corA) had significantly (p < 0.02) reduced survival as compared to the wild type during desiccation survival. Thus, our study provided new insights into the molecular mechanisms utilized by Salmonella for survival against desiccation stress. The findings might be further exploited to develop effective control strategies against Salmonella contamination in low water activity foods and food processing facilities. PMID:28943871

Interaction of Saccharomyces boulardii with Salmonella enterica Serovar Typhimurium Protects Mice and Modifies T84 Cell Response to the Infection

PubMed Central

Martins, Flaviano S.; Dalmasso, Guillaume; Arantes, Rosa M. E.; Doye, Anne; Lemichez, Emmanuel; Lagadec, Patricia; Imbert, Veronique; Peyron, Jean-François; Rampal, Patrick; Nicoli, Jacques R.; Czerucka, Dorota

2010-01-01

Background Salmonella pathogenesis engages host cells in two-way biochemical interactions: phagocytosis of bacteria by recruitment of cellular small GTP-binding proteins induced by the bacteria, and by triggering a pro-inflammatory response through activation of MAPKs and nuclear translocation of NF-κB. Worldwide interest in the use of functional foods containing probiotic bacteria for health promotion and disease prevention has increased significantly. Saccharomyces boulardii is a non-pathogenic yeast used as a probiotic in infectious diarrhea. Methodology/Principal Findings In this study, we reported that S. boulardii (Sb) protected mice from Salmonella enterica serovar Typhimurium (ST)-induced death and prevented bacterial translocation to the liver. At a molecular level, using T84 human colorectal cancer cells, we demonstrate that incubation with Sb before infection totally abolished Salmonella invasion. This correlates with a decrease of activation of Rac1. Sb preserved T84 barrier function and decreased ST-induced IL-8 synthesis. This anti-inflammatory effect was correlated with an inhibitory effect of Sb on ST-induced activation of the MAPKs ERK1/2, p38 and JNK as well as on activation of NF-κB. Electron and confocal microscopy experiments showed an adhesion of bacteria to yeast cells, which could represent one of the mechanisms by which Sb exerts its protective effects. Conclusions Sb shows modulating effects on permeability, inflammation, and signal transduction pathway in T84 cells infected by ST and an in vivo protective effect against ST infection. The present results also demonstrate that Sb modifies invasive properties of Salmonella. PMID:20111723

Mixed biofilm formation by Shiga toxin-producing Escherichia coli and Salmonella enterica serovar Typhimurium enhanced bacterial resistance to sanitization due to extracellular polymeric substances.

PubMed

Wang, Rong; Kalchayanand, Norasak; Schmidt, John W; Harhay, Dayna M

2013-09-01

Shiga toxin-producing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium are important foodborne pathogens capable of forming single-species biofilms or coexisting in multispecies biofilm communities. Bacterial biofilm cells are usually more resistant to sanitization than their planktonic counterparts, so these foodborne pathogens in biofilms pose a serious food safety concern. We investigated how the coexistence of E. coli O157:H7 and Salmonella Typhimurium strains would affect bacterial planktonic growth competition and mixed biofilm composition. Furthermore, we also investigated how mixed biofilm formation would affect bacterial resistance to common sanitizers. Salmonella Typhimurium strains were able to outcompete E. coli strains in the planktonic growth phase; however, mixed biofilm development was highly dependent upon companion strain properties in terms of the expression of bacterial extracellular polymeric substances (EPS), including curli fimbriae and exopolysaccharide cellulose. The EPS-producing strains with higher biofilm-forming abilities were able to establish themselves in mixed biofilms more efficiently. In comparison to single-strain biofilms, Salmonella or E. coli strains with negative EPS expression obtained significantly enhanced resistance to sanitization by forming mixed biofilms with an EPS-producing companion strain of the other species. These observations indicate that the bacterial EPS components not only enhance the sanitizer resistance of the EPS-producing strains but also render protections to their companion strains, regardless of species, in mixed biofilms. Our study highlights the potential risk of cross-contamination by multispecies biofilms in food safety and the need for increased attention to proper sanitization practices in food processing facilities.

Oral immunisation with live aroA attenuated Salmonella enterica serovar Typhimurium expressing the Yersinia pestis V antigen protects mice against plague.

PubMed

Garmory, Helen S; Griffin, Kate F; Brown, Katherine A; Titball, Richard W

2003-06-20

Bubonic and pneumonic plague are caused by the bacterium Yersinia pestis. The V antigen of Y. pestis is a protective antigen against plague. In this study, an aroA attenuated strain of Salmonella enterica serovar Typhimurium (SL3261) has been used to deliver the Y. pestis V antigen as a candidate oral plague vaccine. SL3261 was transformed with the expression plasmid pTrc-LcrV, containing the lcrV gene encoding V antigen. Immunoblot analysis showed V antigen expression in SL3261 in vitro and intragastric immunisation of mice with the recombinant Salmonella resulted in the induction of V antigen-specific serum antibody responses and afforded protection against Y. pestis challenge. However, the antibody responses induced by the recombinant Salmonella did not correlate with the protection afforded, indicating that immune responses other than antibody may play a role in the protection afforded against plague by this candidate vaccine.

Identification of genes associated with survival of salmonellaenterica serovar enteridis in chicken egg albumen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clavijo, Raul I.; Loui, Cindy; Andersen, Gary L.

Salmonella enterica consists of over 2,000 serovars that aremajor causes of morbidity and mortality associated with contaminatedfood. Despite similarities among serovars of Salmonella enterica, manydemonstrate unique host specificities, epidemiological characteristics,and clinical manifestations. One of the unique epidemiologicalcharacteristics of the serovar Enteritidis is that it is the onlybacterium routinely transmitted to humans through intact chicken eggs.Therefore, Salmonella enterica serovar Enteritidis must be able topersist inside chicken eggs to be transmitted to humans, and its survivalin egg is important for its transmission to the human population. Theability of Salmonella enterica serovar Enteritidis to survive in andtransmit through eggs may have contributed tomore » its drastically increasedprevalence in the 1980s and 1990s. In the present study, usingtransposon-mediated mutagenesis, we have identified genes important forthe association of Salmonella enterica serovar Enteritidis with chickeneggs. Our results indicate that genes involved in cell wall structuraland functional integrity, and nucleic acid and amino acid metabolism areimportant for Salmonella enterica serovar Enteritidis to persist in eggalbumen. Two regions unique toSalmonella enterica serovar Enteritidiswere also identified, one of which enhanced the survival of a Salmonellaenterica serovar Typhimurium isolate in egg albumen. The implication ofour results to the serovar specificity of Salmonella enterica is alsoexplored in the present study.« less

Salmonella DIVA vaccine reduces disease, colonization and shedding due to virulent S. Typhimurium infection in swine

PubMed Central

Bearson, Shawn M. D; Brunelle, Brian W; Bayles, Darrell O; Lee, In Soo; Kich, Jalusa D

2017-01-01

Purpose Non-host-adapted Salmonella serovars, including the common human food-borne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), are opportunistic pathogens that can colonize food-producing animals without causing overt disease. Interventions against Salmonella are needed to enhance food safety, protect animal health and allow the differentiation of infected from vaccinated animals (DIVA). Methodology An attenuated S. Typhimurium DIVA vaccine (BBS 866) was characterized for the protection of pigs following challenge with virulent S. Typhimurium. The porcine transcriptional response to BBS 866 vaccination was evaluated. RNA-Seq analysis was used to compare gene expression between BBS 866 and its parent; phenotypic assays were performed to confirm transcriptional differences observed between the strains. Results Vaccination significantly reduced fever and interferon-gamma (IFNγ) levels in swine challenged with virulent S. Typhimurium compared to mock-vaccinated pigs. Salmonella faecal shedding and gastrointestinal tissue colonization were significantly lower in vaccinated swine. RNA-Seq analysis comparing BBS 866 to its parental S. Typhimurium strain demonstrated reduced expression of the genes involved in cellular invasion and bacterial motility; decreased invasion of porcine-derived IPEC-J2 cells and swimming motility for the vaccine strain was consistent with the RNA-Seq analysis. Numerous membrane proteins were differentially expressed, which was an anticipated gene expression pattern due to the targeted deletion of several regulatory genes in the vaccine strain. RNA-Seq analysis indicated that genes involved in the porcine immune and inflammatory response were differentially regulated at 2 days post-vaccination compared to pre-vaccination. Conclusion Evaluation of the S. Typhimurium DIVA vaccine indicates that vaccination will provide both swine health and food safety benefits. PMID:28516860

Distribution of Salmonella serovars and phage types on 80 Ontario swine farms in 2004

PubMed Central

Farzan, Abdolvahab; Friendship, Robert M.; Dewey, Catherine E.; Muckle, Anne C.; Gray, Jeff T.; Funk, Julie

2008-01-01

The objective of this study was to describe the distribution of Salmonella spp. on Ontario grower–finisher pig farms. Eighty swine farms were visited from January through July 2004. On each farm, fecal samples were collected from 5 pens, 2 rectal samples and 1 pooled sample from fresh manure on the floor per pen. Salmonella was isolated from 91 (11%) of the 800 rectal samples and 73 (18%) of the 397 pooled samples. Overall, Salmonella was recovered from 37 (46%) of the 80 farms. On each positive farm, Salmonella was cultured from 1 to 7 pigs or 1 to 5 pens. Of the 37 farms, 18, 13, 5, and 1 yielded 1, 2, 3, and 4 serovars, respectively. The most common serovars were S. Typhimurium var. Copenhagen, S. Infantis, S. Typhimurium, S. Derby, S. Agona, S. Havana, and S. enterica subsp. I:Rough-O. The 3 most frequent phage types were PT 104, PT 104a, and PT 104b. There was a statistically fair agreement between samples collected directly from pigs and pooled pen samples in determining the Salmonella status at the pen and farm level (κ = 0.6, P < 0.0001). However, in 62 pens, Salmonella status, serovars, or phage types differed between the pig and pooled pen samples. The distribution of Salmonella on the swine farms in this study indicates that, in developing an intervention strategy, priority should be given to farms positive for S. Typhimurium var. Copenhagen. Also, the variation in Salmonella status between pig and pooled pen samples deserves consideration in a sampling strategy. PMID:18214155

A comparative study on invasion, survival, modulation of oxidative burst, and nitric oxide responses of macrophages (HD11), and systemic infection in chickens by prevalent poultry Salmonella serovars

USDA-ARS?s Scientific Manuscript database

Poultry is a major reservoir for foodborne Salmonella serovars. Salmonella Typhimurium, S. Enteritidis, S. Heidelberg, S. Kentucky, and S. Senftenberg are the most prevalent serovars in poultry. Information concerning the interactions between different Salmonella species and host cells in poultry i...

Expression and crystallization of SeDsbA, SeDsbL and SeSrgA from Salmonella enterica serovar Typhimurium.

PubMed

Jarrott, R; Shouldice, S R; Guncar, G; Totsika, M; Schembri, M A; Heras, B

2010-05-01

Pathogens require protein-folding enzymes to produce functional virulence determinants. These foldases include the Dsb family of proteins, which catalyze oxidative folding in bacteria. Bacterial disulfide catalytic processes have been well characterized in Escherichia coli K-12 and these mechanisms have been extrapolated to other organisms. However, recent research indicates that the K-12 complement of Dsb proteins is not common to all bacteria. Importantly, many pathogenic bacteria have an extended arsenal of Dsb catalysts that is linked to their virulence. To help to elucidate the process of oxidative folding in pathogens containing a wide repertoire of Dsb proteins, Salmonella enterica serovar Typhimurium has been focused on. This Gram-negative bacterium contains three DsbA proteins: SeDsbA, SeDsbL and SeSrgA. Here, the expression, purification, crystallization and preliminary diffraction analysis of these three proteins are reported. SeDsbA, SeDsbL and SeSrgA crystals diffracted to resolution limits of 1.55, 1.57 and 2.6 A and belonged to space groups P2(1), P2(1)2(1)2 and C2, respectively.

Antimicrobial activity of plant compounds against Salmonella Typhimurium DT104 in ground pork and the influence of heat and storage on the antimicrobial activity.

PubMed

Chen, Cynthia H; Ravishankar, Sadhana; Marchello, John; Friedman, Mendel

2013-07-01

Salmonella enterica is a predominant foodborne pathogen that causes diarrheal illness worldwide. A potential method of inhibiting pathogenic bacterial growth in meat is through the introduction of plant-derived antimicrobials. The objectives of this study were to investigate the influence of heat (70°C for 5 min) and subsequent cold storage (4°C up to 7 days) on the effectiveness of oregano and cinnamon essential oils and powdered olive and apple extracts against Salmonella enterica serovar Typhimurium DT104 in ground pork and to evaluate the activity of the most effective antimicrobials (cinnamon oil and olive extract) at higher concentrations in heated ground pork. The surviving Salmonella populations in two groups (heated and unheated) of antimicrobial-treated pork were compared. Higher concentrations of the most effective compounds were then tested (cinnamon oil at 0.5 to 1.0% and olive extract at 3, 4, and 5%) against Salmonella Typhimurium in heated ground pork. Samples were stored at 4°C and taken on days 0, 3, 5, and 7 for enumeration of survivors. The heating process did not affect the activity of antimicrobials. Significant 1.3- and 3-log reductions were observed with 1.0% cinnamon oil and 5% olive extract, respectively, on day 7. The minimum concentration required to achieve . 1-log reduction in Salmonella population was 0.8% cinnamon oil or 4% olive extract. The results demonstrate the effectiveness of these antimicrobials against multidrug-resistant Salmonella Typhimurium in ground pork and their stability during heating and cold storage. The most active formulations have the potential to enhance the microbial safety of ground pork.

Expression of hilA in response to mild acid stress in Salmonella enterica is serovar and strain dependent.

PubMed

González-Gil, Francisco; Le Bolloch, Alexandre; Pendleton, Sean; Zhang, Nan; Wallis, Audra; Hanning, Irene

2012-05-01

Salmonella enterica is the leading cause of foodborne illness with poultry and poultry products being primary sources of infection. The 2 most common S. enterica serovars associated with human infection are Typhimurium and Enteritidis. However, Kentucky and Heidelburg and the 2 most prevalent serovars isolated from poultry environments. Given the prevalence of other serovars in poultry products and environments, research is needed to understand virulence modulation in response to stress in serovars other than Typhimurium and Enteritidis. Thus, the objective of this research was to compare hilA gene expression (a master regulator of the virulence pathogenicity island) in response to acid stress among different strains and serovars of Salmonella. A total of 11 serovars consisting of 15 strains of S. enterica were utilized for these experiments. Cultures were suspended in tryptic soy broth (TSB) adjusted to pH 7.2, 6.2, or 5.5 with HCl or acetic acid. Total RNA was extracted from cultures at specific time points (0, 2, 4, and 24 h). Gene expression of hilA was measured with quantitative reverse transcriptase real time PCR (qRT-PCR). Growth and pH were measured throughout the 24 h time frame. Regulation of hilA in response to acid stress varied by serovar and strain and type of acid. The results of these experiments indicate that hilA regulation may have some impact on virulence and colonization of S. enterica. However, these results warrant further research to more fully understand the significance of hilA regulation in response to mild acid stress in S. enterica. © 2012 Institute of Food Technologists®

Antimicrobial activity of lauric arginate-coated polylactic acid films against Listeria monocytogenes and Salmonella typhimurium on cooked sliced ham.

PubMed

Theinsathid, Pornpun; Visessanguan, Wonnop; Kruenate, Jittiporn; Kingcha, Yutthana; Keeratipibul, Suwimon

2012-02-01

A novel type of environmentally friendly packaging with antibacterial activity was developed from lauric arginate (LAE)-coating of polylactic acid (PLA) films after surface activation using a corona discharge. Scanning electron microscopy (SEM)-based analysis of the LAE/PLA films confirmed the successful coating of LAE on the PLA surface. The mechanical properties of the LAE/PLA films with different levels of LAE-coating (0% to 2.6%[w/w]) were essentially the same as those of the neat PLA film. The antibacterial activity of the LAE/PLA films against Listeria monocytogenes and Salmonella enterica Serovar Typhimurium (S. Typhimurium) was confirmed by a qualitative modified agar diffusion assay and quantitative JIS Z 2801:2000 method. Using the LAE/PLA film as a food-contact antimicrobial packaging for cooked cured ham, as a model system, suggested a potential application to inhibit L. monocytogenes and S. Typhimurium on ham with a 0.07% (w/w) LAE coating on the PLA when high transparency is required, as evidenced from the 2 to 3 log CFU/tested film lower pathogen growth after 7 d storage but even greater antibacterial activity is obtained with a LAE coating level of 2.6% (w/w) but at the cost of a reduced transparency of the finished product. This article shows how we can simply develop functional green packaging of PLA for food with effective and efficient antimicrobial activity by use of LAE coating on the surface via corona discharge. The effectiveness of an innovative antimicrobial LAE-coated PLA film against foodborne pathogens was demonstrated. Importantly, the application of the LAE to form the LAE-coated PLA film can be customized within current film manufacturing lines. © 2012 Institute of Food Technologists®

Prevalence, serovars, phage types, and antibiotic susceptibilities of Salmonella strains isolated from animals in the United Arab Emirates from 1996 to 2009.

PubMed

Münch, Sebastian; Braun, Peggy; Wernery, Ulrich; Kinne, Jörg; Pees, Michael; Flieger, Antje; Tietze, Erhard; Rabsch, Wolfgang

2012-10-01

The aim of this study was to give some insights into the prevalence, serovars, phage types, and antibiotic resistances of Salmonella from animal origin in the United Arab Emirates. Data on diagnostic samples from animals (n = 20,871) examined for Salmonella between 1996 and 2009 were extracted from the databases of the Central Veterinary Research Laboratory in Dubai and from typed strains (n = 1052) from the Robert Koch Institute, Wernigerode Branch in Germany and analyzed for general and animal-specific trends. Salmonella was isolated from 1,928 (9 %) of the 20,871 samples examined. Among the 1,052 typed strains, most were from camels (n = 232), falcons (n = 166), bustards (n = 101), antelopes (n = 66), and horses (n = 63). The predominant serovars were Salmonella Typhimurium (25 %), Salmonella Kentucky (8 %), followed by Salmonella Frintrop (7 %), and Salmonella Hindmarsh (5 %). When analyzed by animal species, the most frequent serovars in camels were Salmonella Frintrop (28 %) and Salmonella Hindmarsh (21 %), in falcons Salmonella Typhimurium (32 %), in bustards Salmonella Kentucky (19 %), in antelopes Salmonella Typhimurium (9 %), and in horses Salmonella Typhimurium (17 %) and S. Kentucky (16 %). Resistance of all typed Salmonella strains (n = 1052) was most often seen to tetracycline (23 %), streptomycin (22 %), nalidixic acid (18 %), and ampicillin (15 %). These data show trends in the epidemiology of Salmonella in different animal species which can be used as a base for future prevention, control, and therapy strategies.

Development and use of polymerase chain reaction for the specific detection of Salmonella Typhimurium in stool and food samples.

PubMed

Lin, J S; Tsen, H Y

1999-10-01

Salmonella Typhimurium is one of the most important Salmonella serovars that may cause foodborne disease and human salmonellosis infection. Detection of this organism in the clinical samples of persons with gastroenteritis and the food samples associated with such persons may allow us to trace the cause of disease. Because malic acid dehydrogenase, an enzyme of the citric acid cycle, is common to organisms, the gene (mdh) coding for this enzyme was selected for the design of Salmonella Typhimurium-specific polymerase chain reaction (PCR) primers. By comparison of the mdh gene sequences of Salmonella Typhimurium and other Salmonella serotypes and of some isolates of other genera, two oligonucleotides were designed and used as PCR primers for the specific detection of Salmonella Typhimurium. The molecular weight of the PCR product was 261 bp as expected. Salmonella serovars other than Salmonella Typhimurium and isolates of other genera in the Enterobacteriaceae that is closely related to Salmonella did not generate any false-positive results. When this primer pair was used for the detection of Salmonella Typhimurium cells artificially inoculated into human stool specimens and food samples, such as milk and raw chicken meat, levels as low as 10(0) CFU per 0.1 g of stool specimen or per ml of milk or food homogenate could be detected if an 8- to 12-h preculture step using combined lactose-tetrathionate broth was performed prior to the PCR.

Human migration is important in the international spread of exotic Salmonella serovars in animal and human populations.

PubMed

Iveson, J B; Bradshaw, S D; How, R A; Smith, D W

2014-11-01

The exposure of indigenous humans and native fauna in Australia and the Wallacea zoogeographical region of Indonesia to exotic Salmonella serovars commenced during the colonial period and has accelerated with urbanization and international travel. In this study, the distribution and prevalence of exotic Salmonella serovars are mapped to assess the extent to which introduced infections are invading native wildlife in areas of high natural biodiversity under threat from expanding human activity. The major exotic Salmonella serovars, Bovismorbificans, Derby, Javiana, Newport, Panama, Saintpaul and Typhimurium, isolated from wildlife on populated coastal islands in southern temperate areas of Western Australia, were mostly absent from reptiles and native mammals in less populated tropical areas of the state. They were also not recorded on the uninhabited Mitchell Plateau or islands of the Bonaparte Archipelago, adjacent to south-eastern Indonesia. Exotic serovars were, however, isolated in wildlife on 14/17 islands sampled in the Wallacea region of Indonesia and several islands off the west coast of Perth. Increases in international tourism, involving islands such as Bali, have resulted in the isolation of a high proportion of exotic serovar infections suggesting that densely populated island resorts in the Asian region are acting as staging posts for the interchange of Salmonella infections between tropical and temperate regions.

SadA, a trimeric autotransporter from Salmonella enterica serovar Typhimurium, can promote biofilm formation and provides limited protection against infection.

PubMed

Raghunathan, Dhaarini; Wells, Timothy J; Morris, Faye C; Shaw, Robert K; Bobat, Saeeda; Peters, Sarah E; Paterson, Gavin K; Jensen, Karina Tveen; Leyton, Denisse L; Blair, Jessica M A; Browning, Douglas F; Pravin, John; Flores-Langarica, Adriana; Hitchcock, Jessica R; Moraes, Claudia T P; Piazza, Roxane M F; Maskell, Duncan J; Webber, Mark A; May, Robin C; MacLennan, Calman A; Piddock, Laura J; Cunningham, Adam F; Henderson, Ian R

2011-11-01

Salmonella enterica is a major cause of morbidity worldwide and mortality in children and immunocompromised individuals in sub-Saharan Africa. Outer membrane proteins of Salmonella are of significance because they are at the interface between the pathogen and the host, they can contribute to adherence, colonization, and virulence, and they are frequently targets of antibody-mediated immunity. In this study, the properties of SadA, a purported trimeric autotransporter adhesin of Salmonella enterica serovar Typhimurium, were examined. We demonstrated that SadA is exposed on the Salmonella cell surface in vitro and in vivo during infection of mice. Expression of SadA resulted in cell aggregation, biofilm formation, and increased adhesion to human intestinal Caco-2 epithelial cells. Immunization of mice with folded, full-length, purified SadA elicited an IgG response which provided limited protection against bacterial challenge. When anti-SadA IgG titers were enhanced by administering alum-precipitated protein, a modest additional protection was afforded. Therefore, despite SadA having pleiotropic functions, it is not a dominant, protective antigen for antibody-mediated protection against Salmonella.

Allelic Variation in TLR4 Is Linked to Susceptibility to Salmonella enterica Serovar Typhimurium Infection in Chickens

PubMed Central

Leveque, Gary; Forgetta, Vincenzo; Morroll, Shaun; Smith, Adrian L.; Bumstead, Nat; Barrow, Paul; Loredo-Osti, J. C.; Morgan, Kenneth; Malo, Danielle

2003-01-01

Toll-like receptor 4 (TLR4) is part of a group of evolutionarily conserved pattern recognition receptors involved in the activation of the immune system in response to various pathogens and in the innate defense against infection. We describe here the cloning and characterization of the avian orthologue of mammalian TLR4. Chicken TLR4 encodes a 843-amino-acid protein that contains a leucine-rich repeat extracellular domain, a short transmembrane domain typical of type I transmembrane proteins, and a Toll-interleukin-1R signaling domain characteristic of all TLR proteins. The chicken TLR4 protein shows 46% identity (64% similarity) to human TLR4 and 41% similarity to other TLR family members. Northern blot analysis reveals that TLR4 is expressed at approximately the same level in all tissues tested, including brain, thymus, kidney, intestine, muscle, liver, lung, bursa of Fabricius, heart, and spleen. The probe detected only one transcript of ca. 4.4 kb in length for all tissues except muscle where the size of TLR4 mRNA was ca. 9.6 kb. We have mapped TLR4 to microchromosome E41W17 in a region harboring the gene for tenascin C and known to be well conserved between the chicken and mammalian genomes. This region of the chicken genome was shown previously to harbor a Salmonella susceptibility locus. By using linkage analysis, TLR4 was shown to be linked to resistance to infection with Salmonella enterica serovar Typhimurium in chickens (likelihood ratio test of 10.2, P = 0.00138), suggesting a role of TLR4 in the host response of chickens to Salmonella infection. PMID:12595422

Inactivation of Salmonella Typhimurium and quality preservation of cherry tomatoes by in-package aerosolization of antimicrobials

USDA-ARS?s Scientific Manuscript database

The purpose of the present study was to investigate the efficacy of in-package aerosolized aqueous sanitizers in reducing populations of attenuated Salmonella enterica serovar Typhimurium inoculated on tomato fruit and in maintaining fruit quality. Cherry tomatoes were inoculated with a cocktail of ...

Human Milk Mucin 1 and Mucin 4 Inhibit Salmonella enterica Serovar Typhimurium Invasion of Human Intestinal Epithelial Cells In Vitro123

PubMed Central

Liu, Bo; Yu, Zhuoteng; Chen, Ceng; Kling, David E.; Newburg, David S.

2012-01-01

Many human milk glycans inhibit pathogen binding to host receptors and their consumption by infants is associated with reduced risk of disease. Salmonella infection is more frequent among infants than among the general population, but the incidence is lower in breast-fed babies, suggesting that human milk could contain components that inhibit Salmonella. This study aimed to test whether human milk per se inhibits Salmonella invasion of human intestinal epithelial cells in vitro and, if so, to identify the milk components responsible for inhibition. Salmonella enterica serovar Typhimurium SL1344 (SL1344) invasion of FHs 74 Int and Caco-2 cells were the models of human intestinal epithelium infection. Internalization of fluorescein-5-isothiocyanate–labeled SL1344 into intestinal cells was measured by flow cytometry to quantify infection. Human milk and its fractions inhibited infection; the inhibitory activity localized to the high molecular weight glycans. Mucin 1 and mucin 4 were isolated to homogeneity. At 150 μg/L, a typical concentration in milk, human milk mucin 1 and mucin 4 inhibited SL1344 invasion of both target cell types. These mucins inhibited SL1344 invasion of epithelial cells in a dose-dependent manner. Thus, mucins may prove useful as a basis for developing novel oral prophylactic and therapeutic agents that inhibit infant diseases caused by Salmonella and related pathogens. PMID:22718031

Comparison of methods for quantitating Salmonella enterica Typhimurium and Heidelberg strain attachment to reusable plastic shipping container coupons and preliminary assessment of sanitizer efficacy.

PubMed

Shi, Zhaohao; Baker, Christopher A; Lee, Sang In; Park, Si Hong; Kim, Sun Ae; Ricke, Steven C

2016-09-01

Salmonella serovars, one of the leading contributors to foodborne illness and are especially problematic for foods that are not cooked before consumption, such as fresh produce. The shipping containers that are used to transport and store fresh produce may play a role in cross contamination and subsequent illnesses. However, methods for quantitatively attached cells are somewhat variable. The overall goal of this study was to compare conventional plating with molecular methods for quantitating attached representative strains for Salmonella Typhimurium and Heidelberg on reusable plastic containers (RPC) coupons, respectively. We attached Salmonella enterica serovar Typhimurium ATCC 14028 and serovar Heidelberg SL486 (parent and an antibiotic resistant marker strain) to plastic coupons (2.54 cm(2)) derived from previously used shipping containers by growing for 72 h in tryptic soy broth. The impact of the concentration of sanitizer on log reductions between unsanitized and sanitized coupons was evaluated by exposing attached S. Typhimurium cells to 200 ppm and 200,000 ppm sodium hypochlorite (NaClO). Differences in sanitizer effectiveness between serovars were also evaluated with attached S. Typhimurium compared to attached S. Heidelberg populations after being exposed to 200 ppm peracetic acid (PAA). Treatment with NaClO caused an average of 2.73 ± 0.23 log CFU of S. Typhimurium per coupon removed with treatment at 200 ppm while 3.36 ± 0.54 log CFU were removed at 200,000 ppm. Treatment with PAA caused an average of 2.62 ± 0.15 log CFU removed for S. Typhimurium and 1.41 ± 0.17 log CFU for S. Heidelberg (parent) and 1.61 ± 0.08 log CFU (marker). Lastly, scanning electron microscopy (SEM) was used to visualize cell attachment and coupon surface topography. SEM images showed that remaining attached cell populations were visible even after sanitizer application. Conventional plating and qPCR yielded similar levels of enumerated bacterial populations

A community effort towards a knowledge-base and mathematical model of the human pathogen Salmonella Typhimurium LT2

USDA-ARS?s Scientific Manuscript database

Metabolic reconstructions (MRs) are common denominators in systems biology and represent biochemical, genetic, and genomic (BiGG) knowledge-bases for target organisms by capturing currently available information in a consistent, structured manner. Salmonella enterica subspecies I serovar Typhimurium...

Protective effect of Lactobacillus casei strain Shirota against lethal infection with multi-drug resistant Salmonella enterica serovar Typhimurium DT104 in mice.

PubMed

Asahara, T; Shimizu, K; Takada, T; Kado, S; Yuki, N; Morotomi, M; Tanaka, R; Nomoto, K

2011-01-01

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. Explosive intestinal growth and subsequent lethal extra-intestinal translocation after oral infection with DT104 during fosfomycin (FOM) administration was significantly inhibited by continuous oral administration of Lactobacillus casei strain Shirota (LcS), which is naturally resistant to FOM, at a dose of 10(8) colony-forming units per mouse daily to mice. Comparison of the anti-Salmonella activity of several Lactobacillus type strains with natural resistance to FOM revealed that Lactobacillus brevis ATCC 14869(T) , Lactobacillus plantarum ATCC 14917(T) , Lactobacillus reuteri JCM 1112(T) , Lactobacillus rhamnosus ATCC 7469(T) and Lactobacillus salivarius ATCC 11741(T) conferred no activity even when they obtained the high population levels almost similar to those of the effective strains such as LcS, Lact. casei ATCC 334(T) and Lactobacillus zeae ATCC 15820(T) . The increase in concentration of organic acids and maintenance of the lower pH in the intestine because of Lactobacillus colonization were correlated with the anti-infectious activity. Moreover, heat-killed LcS was not protective against the infection, suggesting that the metabolic activity of lactobacilli is important for the anti-infectious activity. These results suggest that certain lactobacilli in combination with antibiotics may be useful for prophylaxis against opportunistic intestinal infections by multi-drug resistant pathogens, such as DT104. Antibiotics such as FOM disrupt the metabolic activity of the intestinal microbiota that produce organic acids, and that only probiotic strains that are metabolically active in vivo should be selected to prevent intestinal infection when used clinically in combination with certain antibiotics. © 2010 The Authors. Journal of Applied Microbiology �

Identification of Salmonella enterica Serovar Typhimurium Genes Regulated during Biofilm Formation on Cholesterol Gallstone Surfaces

PubMed Central

Gonzalez-Escobedo, Geoffrey

2013-01-01

Salmonella spp. are able to form biofilms on abiotic and biotic surfaces. In vivo studies in our laboratory have shown that Salmonella can form biofilms on the surfaces of cholesterol gallstones in the gallbladders of mice and human carriers. Biofilm formation on gallstones has been demonstrated to be a mechanism of persistence. The purpose of this work was to identify and evaluate Salmonella sp. cholesterol-dependent biofilm factors. Differential gene expression analysis between biofilms on glass or cholesterol-coated surfaces and subsequent quantitative real-time PCR (qRT-PCR) revealed that type 1 fimbria structural genes and a gene encoding a putative outer membrane protein (ycfR) were specifically upregulated in Salmonella enterica serovar Typhimurium biofilms grown on cholesterol-coated surfaces. Spatiotemporal expression of ycfR and FimA verified their regulation during biofilm development on cholesterol-coated surfaces. Surprisingly, confocal and scanning electron microscopy demonstrated that a mutant of type 1 fimbria structural genes (ΔfimAICDHF) and a ycfR mutant showed increased biofilm formation on cholesterol-coated surfaces. In vivo experiments using Nramp1+/+ mice harboring gallstones showed that only the ΔycfR mutant formed extensive biofilms on mouse gallstones at 7 and 21 days postinfection; ΔfimAICDHF was not observed on gallstone surfaces after the 7-day-postinfection time point. These data suggest that in Salmonella spp., wild-type type 1 fimbriae are important for attachment to and/or persistence on gallstones at later points of chronic infection, whereas YcfR may represent a specific potential natural inhibitor of initial biofilm formation on gallstones. PMID:23897604

Dissemination of clonal Salmonella enterica serovar Typhimurium isolates causing salmonellosis in Mauritius.

PubMed

Issack, Mohammad I; Garcia-Migura, Lourdes; Ramsamy, Veemala D; Svendsen, Christina A; Pornruangwong, Srirat; Pulsrikarn, Chaiwat; Hendriksen, Rene S

2013-07-01

Salmonella enterica serotype Typhimurium is one of the leading causes of salmonellosis in Mauritius, where it has also been associated with outbreaks of foodborne illness. However, little is known about its molecular epidemiology in the country. This study was therefore undertaken to investigate the clonality and source of Salmonella Typhimurium in Mauritius by studying human, food, and poultry isolates by pulsed-field gel electrophoresis (PFGE) and antibiotic minimum inhibitory concentration determination. Forty-nine isolates collected between 2008 and 2011 were analyzed, including 25 stool isolates from foodborne illness outbreaks and sporadic gastroenteritis cases, four blood isolates, one postmortem colon isolate, 14 food isolates, and five poultry isolates. All isolates were pansusceptible to the 16 antibiotics tested, except for two isolates that were resistant to sulfamethoxazole and trimethoprim. Overall characterization of the isolates by PFGE digested with XbaI and BlnI resulted in eight different patterns. The largest of the clusters in the composite dataset consisted of 20 isolates, including two raw chicken isolates, four poultry isolates, and nine human stool isolates from two outbreaks. A second cluster consisted of 18 isolates, of which 12 originated from human blood and stool samples from both sporadic and outbreak cases. Six food isolates were also found in this cluster, including isolates from raw and grilled chicken, marlin mousse, and cooked pork. One poultry isolate had a closely related PFGE pattern. The results indicate that one clone of Salmonella Typhimurium found in poultry has been causing outbreaks of foodborne illness in Mauritius and another clone that has caused many cases of gastrointestinal illness and bacteremia in humans could also be linked to poultry. Thus, poultry appears to be a major reservoir for Salmonella Typhimurium in Mauritius. Initiating on-farm control strategies and measures against future dissemination may

Deletion of the gene encoding the glycolytic enzyme triosephosphate isomerase (tpi) alters morphology of Salmonella enterica serovar Typhimurium and decreases fitness in mice.

PubMed

Paterson, Gavin K; Cone, Danielle B; Northen, Helen; Peters, Sarah E; Maskell, Duncan J

2009-05-01

The glycolytic enzyme triosephosphate isomerase (tpi) (EC 5.3.1.1) plays a key role in central carbon metabolism yet few studies have characterized isogenic bacterial mutants lacking this enzyme and none have examined its role in the in vivo fitness of a bacterial pathogen. Here we have deleted tpiA in Salmonella enterica serovar Typhimurium and found that the mutant had an altered morphology, displaying an elongated shape compared with the wild type. In a mouse model of typhoid fever the tpiA mutant was attenuated for growth as assessed by bacterial counts in the livers and spleens of infected mice. However, this attenuation was not deemed sufficient for consideration of a tpiA mutant as a live attenuated vaccine strain. These phenotypes were complemented by provision of tpiA on pBR322. We therefore provide the first demonstration that tpiA is required for full in vivo fitness of a bacterial pathogen, and that it has a discernable impact on cell morphology.

Development of a novel in-water vaccination protocol for DNA adenine methylase deficient Salmonella enterica serovar Typhimurium vaccine in adult sheep.

PubMed

Mohler, V L; Heithoff, D M; Mahan, M J; Hornitzky, M A; Thomson, P C; House, J K

2012-02-14

Intensive livestock production is associated with an increased incidence of salmonellosis. The risk of infection and the subsequent public health concern is attributed to increased pathogen exposure and disease susceptibility due to multiple stressors experienced by livestock from farm to feedlot. Traditional parenteral vaccine methods can further stress susceptible populations and cause carcass damage, adverse reactions, and resultant increased production costs. As a potential means to address these issues, in-water delivery of live attenuated vaccines affords a low cost, low-stress method for immunization of livestock populations that is not associated with the adverse handling stressors and injection reactions associated with parenteral administration. We have previously established that in-water administration of a Salmonella enterica serovar Typhimurium dam vaccine conferred significant protection in livestock. While these experimental trials hold significant promise, the ultimate measure of the vaccine will not be established until it has undergone clinical testing in the field wherein environmental and sanitary conditions are variable. Here we show that in-water administration of a S. Typhimurium dam attenuated vaccine was safe, stable, and well-tolerated in adult sheep. The dam vaccine did not alter water consumption or vaccine dosing; remained viable under a wide range of temperatures (21-37°C); did not proliferate within fecal-contaminated trough water; and was associated with minimal fecal shedding and clinical disease as a consequence of vaccination. The capacity of Salmonella dam attenuated vaccines to be delivered in drinking water to protect livestock from virulent Salmonella challenge offers an effective, economical, stressor-free Salmonella prophylaxis for intensive livestock production systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Functional Activity of Antibodies Directed towards Flagellin Proteins of Non-Typhoidal Salmonella

PubMed Central

Boyd, Mary A.; Wang, Jin Y.; Tulapurkar, Mohan E.; Pasetti, Marcela F.; Levine, Myron M.; Simon, Raphael

2016-01-01

Non-typhoidal Salmonella (NTS) serovars Typhimurium and Enteritidis are major causes of invasive bacterial infections in children under 5 years old in sub-Saharan Africa, with case fatality rates of ~20%. There are no licensed NTS vaccines for humans. Vaccines that induce antibodies against a Salmonella Typhi surface antigen, Vi polysaccharide, significantly protect humans against typhoid fever, establishing that immune responses to Salmonella surface antigens can be protective. Flagella proteins, abundant surface antigens in Salmonella serovars that cause human disease, are also powerful immunogens, but the functional capacity of elicited anti-flagellar antibodies and their role in facilitating bacterial clearance has been unclear. We examined the ability of anti-flagellar antibodies to mediate microbial killing by immune system components in-vitro and assessed their role in protecting mice against invasive Salmonella infection. Polyclonal (hyperimmune sera) and monoclonal antibodies raised against phase 1 flagellin proteins of S. Enteritidis and S. Typhimurium facilitated bacterial uptake and killing of the homologous serovar pathogen by phagocytes. Polyclonal anti-flagellar antibodies accompanied by complement also achieved direct bacterial killing. Serum bactericidal activity was restricted to Salmonella serovars expressing the same flagellin used as immunogen. Notably, individual anti-flagellin monoclonal antibodies with complement were not bactericidal, but this biological activity was restored when different monoclonal anti-flagellin antibodies were combined. Passive transfer immunization with a monoclonal IgG antibody specific for phase 1 flagellin from S. Typhimurium protected mice against lethal challenge with a representative African invasive S. Typhimurium strain. These findings have relevance for the use of flagellin proteins in NTS vaccines, and confirm the role of anti-flagellin antibodies as mediators of protective immunity. PMID:26998925

Novel small RNA (sRNA) landscape of the starvation-stress response transcriptome of Salmonella enterica serovar typhimurium.

PubMed

Amin, Shivam V; Roberts, Justin T; Patterson, Dillon G; Coley, Alexander B; Allred, Jonathan A; Denner, Jason M; Johnson, Justin P; Mullen, Genevieve E; O'Neal, Trenton K; Smith, Jason T; Cardin, Sara E; Carr, Hank T; Carr, Stacie L; Cowart, Holly E; DaCosta, David H; Herring, Brendon R; King, Valeria M; Polska, Caroline J; Ward, Erin E; Wise, Alice A; McAllister, Kathleen N; Chevalier, David; Spector, Michael P; Borchert, Glen M

2016-01-01

Small RNAs (sRNAs) are short (∼50-200 nucleotides) noncoding RNAs that regulate cellular activities across bacteria. Salmonella enterica starved of a carbon-energy (C) source experience a host of genetic and physiological changes broadly referred to as the starvation-stress response (SSR). In an attempt to identify novel sRNAs contributing to SSR control, we grew log-phase, 5-h C-starved and 24-h C-starved cultures of the virulent Salmonella enterica subspecies enterica serovar Typhimurium strain SL1344 and comprehensively sequenced their small RNA transcriptomes. Strikingly, after employing a novel strategy for sRNA discovery based on identifying dynamic transcripts arising from "gene-empty" regions, we identify 58 wholly undescribed Salmonella sRNA genes potentially regulating SSR averaging an ∼1,000-fold change in expression between log-phase and C-starved cells. Importantly, the expressions of individual sRNA loci were confirmed by both comprehensive transcriptome analyses and northern blotting of select candidates. Of note, we find 43 candidate sRNAs share significant sequence identity to characterized sRNAs in other bacteria, and ∼70% of our sRNAs likely assume characteristic sRNA structural conformations. In addition, we find 53 of our 58 candidate sRNAs either overlap neighboring mRNA loci or share significant sequence complementarity to mRNAs transcribed elsewhere in the SL1344 genome strongly suggesting they regulate the expression of transcripts via antisense base-pairing. Finally, in addition to this work resulting in the identification of 58 entirely novel Salmonella enterica genes likely participating in the SSR, we also find evidence suggesting that sRNAs are significantly more prevalent than currently appreciated and that Salmonella sRNAs may actually number in the thousands.

Novel small RNA (sRNA) landscape of the starvation-stress response transcriptome of Salmonella enterica serovar typhimurium

PubMed Central

Amin, Shivam V.; Roberts, Justin T.; Patterson, Dillon G.; Coley, Alexander B.; Allred, Jonathan A.; Denner, Jason M.; Johnson, Justin P.; Mullen, Genevieve E.; O'Neal, Trenton K.; Smith, Jason T.; Cardin, Sara E.; Carr, Hank T.; Carr, Stacie L.; Cowart, Holly E.; DaCosta, David H.; Herring, Brendon R.; King, Valeria M.; Polska, Caroline J.; Ward, Erin E.; Wise, Alice A.; McAllister, Kathleen N.; Chevalier, David; Spector, Michael P.; Borchert, Glen M.

2016-01-01

ABSTRACT Small RNAs (sRNAs) are short (∼50–200 nucleotides) noncoding RNAs that regulate cellular activities across bacteria. Salmonella enterica starved of a carbon-energy (C) source experience a host of genetic and physiological changes broadly referred to as the starvation-stress response (SSR). In an attempt to identify novel sRNAs contributing to SSR control, we grew log-phase, 5-h C-starved and 24-h C-starved cultures of the virulent Salmonella enterica subspecies enterica serovar Typhimurium strain SL1344 and comprehensively sequenced their small RNA transcriptomes. Strikingly, after employing a novel strategy for sRNA discovery based on identifying dynamic transcripts arising from “gene-empty” regions, we identify 58 wholly undescribed Salmonella sRNA genes potentially regulating SSR averaging an ∼1,000-fold change in expression between log-phase and C-starved cells. Importantly, the expressions of individual sRNA loci were confirmed by both comprehensive transcriptome analyses and northern blotting of select candidates. Of note, we find 43 candidate sRNAs share significant sequence identity to characterized sRNAs in other bacteria, and ∼70% of our sRNAs likely assume characteristic sRNA structural conformations. In addition, we find 53 of our 58 candidate sRNAs either overlap neighboring mRNA loci or share significant sequence complementarity to mRNAs transcribed elsewhere in the SL1344 genome strongly suggesting they regulate the expression of transcripts via antisense base-pairing. Finally, in addition to this work resulting in the identification of 58 entirely novel Salmonella enterica genes likely participating in the SSR, we also find evidence suggesting that sRNAs are significantly more prevalent than currently appreciated and that Salmonella sRNAs may actually number in the thousands. PMID:26853797

Salmonella Typhimurium and Multidirectional Communication in the Gut

PubMed Central

Gart, Elena V.; Suchodolski, Jan S.; Welsh, Thomas H.; Alaniz, Robert C.; Randel, Ronald D.; Lawhon, Sara D.

2016-01-01

The mammalian digestive tract is home to trillions of microbes, including bacteria, archaea, protozoa, fungi, and viruses. In monogastric mammals the stomach and small intestine harbor diverse bacterial populations but are typically less populated than the colon. The gut bacterial community (microbiota hereafter) varies widely among different host species and individuals within a species. It is influenced by season of the year, age of the host, stress and disease. Ideally, the host and microbiota benefit each other. The host provides nutrients to the microbiota and the microbiota assists the host with digestion and nutrient metabolism. The resident microbiota competes with pathogens for space and nutrients and, through this competition, protects the host in a phenomenon called colonization resistance. The microbiota participates in development of the host immune system, particularly regulation of autoimmunity and mucosal immune response. The microbiota also shapes gut–brain communication and host responses to stress; and, indeed, the microbiota is a newly recognized endocrine organ within mammalian hosts. Salmonella enterica serovar Typhimurium (S. Typhimurium hereafter) is a food-borne pathogen which adapts to and alters the gastrointestinal (GI) environment. In the GI tract, S. Typhimurium competes with the microbiota for nutrients and overcomes colonization resistance to establish infection. To do this, S. Typhimurium uses multiple defense mechanisms to resist environmental stressors, like the acidic pH of the stomach, and virulence mechanisms which allow it to invade the intestinal epithelium and disseminate throughout the host. To coordinate gene expression and disrupt signaling within the microbiota and between host and microbiota, S. Typhimurium employs its own chemical signaling and may regulate host hormone metabolism. This review will discuss the multidirectional interaction between S. Typhimurium, host and microbiota as well as mechanisms that allow S

Evaluation of a lytic bacteriophage, Φ st1, for biocontrol of Salmonella enterica serovar Typhimurium in chickens.

PubMed

Wong, Chuan Loo; Sieo, Chin Chin; Tan, Wen Siang; Abdullah, Norhani; Hair-Bejo, Mohd; Abu, Jalila; Ho, Yin Wan

2014-02-17

In this study, a Salmonella Typhimurium lytic bacteriophage, Φ st1, which was isolated from chicken faecal material, was evaluated as a candidate for biocontrol of Salmonella in chickens. The morphology of Φ st1 showed strong resemblance to members of the Siphoviridae family. Φ st1 was observed to be a DNA phage with an estimated genome size of 121 kbp. It was found to be able to infect S. Typhimurium and S. Hadar, with a stronger lytic activity against the former. Subsequent characterisation of Φ st1 against S. Typhimurium showed that Φ st1 has a latent period of 40 min with an average burst size of 22 particles per infective centre. Approximately 86.1% of the phage adsorbed to the host cells within the initial 5 min of infection. At the optimum multiplicity of infection (MOI) (0.1), the highest reduction rate of S. Typhimurium (6.6 log₁₀ CFU/ml) and increment in phage titre (3.8 log₁₀ PFU/ml) was observed. Φ st1 produced adsorption rates of 88.4-92.2% at pH7-9 and demonstrated the highest bacteria reduction (6.6 log₁₀ CFU/ml) at pH9. Φ st1 also showed an insignificant different (P>0.05) reduction rate of host cells at 37 °C (6.4 log₁₀ CFU/ml) and 42 °C (6.0 log₁₀ CFU/ml). The in vivo study using Φ st1 showed that intracloacal inoculation of ~10¹² PFU/ml of the phage in the chickens challenged with ~10¹⁰ CFU/ml of S. Typhimurium was able to reduce (P<0.05) the S. Typhimurium more rapidly than the untreated group. The Salmonella count reduced to 2.9 log₁₀ CFU/ml within 6h of post-challenge and S. Typhimurium was not detected at and after 24h of post-challenge. Reduction of Salmonella count in visceral organs was also observed at 6h post-challenge. Approximately 1.6 log₁₀ FU/ml Φ st1 was found to persist in the caecal wall of the chicks at 72 h of post-challenge. The present study indicated that Φ st1 may serve as a potential biocontrol agent to reduce the Salmonella count in caecal content of chickens. Copyright © 2013

L-Asparaginase II Produced by Salmonella Typhimurium Inhibits T Cell Responses and Mediates Virulence

PubMed Central

Kullas, Amy L.; McClelland, Michael; Yang, Hee-Jeong; Tam, Jason W.; Torres, AnnMarie; Porwollik, Steffen; Mena, Patricio; McPhee, Joseph B.; Bogomolnaya, Lydia; Andrews-Polymenis, Helene; van der Velden, Adrianus W.M.

2013-01-01

SUMMARY Salmonella enterica serovar Typhimurium avoids clearance by the host immune system by suppressing T cell responses; however, the mechanisms that mediate this immunosuppression remain unknown. We show that S. Typhimurium inhibit T cell responses by producing L-Asparaginase II, which catalyzes the hydrolysis of L-asparagine to aspartic acid and ammonia. L-Asparaginase II is necessary and sufficient to suppress T cell blastogenesis, cytokine production, and proliferation and to downmodulate expression of the T cell receptor. Furthermore, S. Typhimurium-induced inhibition of T cells in vitro is prevented upon addition of L-asparagine. S. Typhimurium lacking the L-Asparaginase II gene (STM3106) are unable to inhibit T cell responses and exhibit attenuated virulence in vivo. L-Asparaginases are used to treat acute lymphoblastic leukemia through mechanisms that likely involve amino acid starvation of leukemic cells, and these findings indicate that pathogens similarly use L-asparagine deprivation to limit T cell responses. PMID:23245323

Iron acquisition pathways and colonization of the inflamed intestine by Salmonella enterica serovar Typhimurium

PubMed Central

Costa, Luciana F.; Mol, Juliana P. S.; Silva, Ana Patricia C.; Macêdo, Auricélio A.; Silva, Teane M. A.; Alves, Geraldo E. S.; Winter, Sebastian; Winter, Maria G.; Velazquez, Eric M.; Byndloss, Mariana X.; Bäumler, Andreas J.; Tsolis, Renée M.; Paixão, Tatiane A.; Santos, Renato L.

2016-01-01

Salmonella enterica serotype Typhimurium is able to expand in the lumen of the inflamed intestine through mechanisms that have not been fully resolved. Here we utilized streptomycin-pretreated mice and dextran sodium sulfate (DSS)-treated mice to investigate how pathways for S. Typhimurium iron acquisition contribute to pathogen expansion in the inflamed intestine. Competitive infection with an iron uptake-proficient S. Typhimurium strain and mutant strains lacking tonB feoB, feoB, tonB or iroN in streptomycin pretreated mice demonstrated that ferric iron uptake requiring IroN and TonB conferred a fitness advantage during growth in the inflamed intestine. However, the fitness advantage conferred by ferrous iron uptake mechanisms was independent of inflammation and was only apparent in models where the normal microbiota composition had been disrupted by antibiotic treatment. PMID:27760693

Evaluation of near-infrared pasteurization in controlling Escherichia coli O157:H7, Salmonella enterica serovar typhimurium, and Listeria monocytogenes in ready-to-eat sliced ham.

PubMed

Ha, Jae-Won; Ryu, Sang-Ryeol; Kang, Dong-Hyun

2012-09-01

This study was conducted to investigate the efficacy of near-infrared (NIR) heating to reduce Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes in ready-to-eat (RTE) sliced ham compared to conventional convective heating, and the effect of NIR heating on quality was determined by measuring the color and texture change. A cocktail of three pathogens was inoculated on the exposed or protected surfaces of ham slices, followed by NIR or conventional heating at 1.8 kW. NIR heating for 50 s achieved 4.1-, 4.19-, and 3.38-log reductions in surface-inoculated S. Typhimurium, E. coli O157:H7, and L. monocytogenes, respectively, whereas convective heating needed 180 s to attain comparable reductions for each pathogen. There were no statistically significant (P > 0.05) differences in reduction between surface- and internally inoculated pathogens at the end of NIR treatment (50 s). However, when treated with conventional convective heating, significant (P < 0.05) differences were observed at the final stages of the treatment (150 and 180 s). Color values and texture parameters of NIR-treated (50-s treatment) ham slices were not significantly (P > 0.05) different from those of nontreated samples. These results suggest that NIR heating can be applied to control internalized pathogens as well as surface-adhering pathogens in RTE sliced meats without affecting product quality.

Evaluation of Near-Infrared Pasteurization in Controlling Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Ready-To-Eat Sliced Ham

PubMed Central

Ha, Jae-Won; Ryu, Sang-Ryeol

2012-01-01

This study was conducted to investigate the efficacy of near-infrared (NIR) heating to reduce Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes in ready-to-eat (RTE) sliced ham compared to conventional convective heating, and the effect of NIR heating on quality was determined by measuring the color and texture change. A cocktail of three pathogens was inoculated on the exposed or protected surfaces of ham slices, followed by NIR or conventional heating at 1.8 kW. NIR heating for 50 s achieved 4.1-, 4.19-, and 3.38-log reductions in surface-inoculated S. Typhimurium, E. coli O157:H7, and L. monocytogenes, respectively, whereas convective heating needed 180 s to attain comparable reductions for each pathogen. There were no statistically significant (P > 0.05) differences in reduction between surface- and internally inoculated pathogens at the end of NIR treatment (50 s). However, when treated with conventional convective heating, significant (P < 0.05) differences were observed at the final stages of the treatment (150 and 180 s). Color values and texture parameters of NIR-treated (50-s treatment) ham slices were not significantly (P > 0.05) different from those of nontreated samples. These results suggest that NIR heating can be applied to control internalized pathogens as well as surface-adhering pathogens in RTE sliced meats without affecting product quality. PMID:22773635

SadA, a Trimeric Autotransporter from Salmonella enterica Serovar Typhimurium, Can Promote Biofilm Formation and Provides Limited Protection against Infection ▿ †

PubMed Central

Raghunathan, Dhaarini; Wells, Timothy J.; Morris, Faye C.; Shaw, Robert K.; Bobat, Saeeda; Peters, Sarah E.; Paterson, Gavin K.; Jensen, Karina Tveen; Leyton, Denisse L.; Blair, Jessica M. A.; Browning, Douglas F.; Pravin, John; Flores-Langarica, Adriana; Hitchcock, Jessica R.; Moraes, Claudia T. P.; Piazza, Roxane M. F.; Maskell, Duncan J.; Webber, Mark A.; May, Robin C.; MacLennan, Calman A.; Piddock, Laura J.; Cunningham, Adam F.; Henderson, Ian R.

2011-01-01

Salmonella enterica is a major cause of morbidity worldwide and mortality in children and immunocompromised individuals in sub-Saharan Africa. Outer membrane proteins of Salmonella are of significance because they are at the interface between the pathogen and the host, they can contribute to adherence, colonization, and virulence, and they are frequently targets of antibody-mediated immunity. In this study, the properties of SadA, a purported trimeric autotransporter adhesin of Salmonella enterica serovar Typhimurium, were examined. We demonstrated that SadA is exposed on the Salmonella cell surface in vitro and in vivo during infection of mice. Expression of SadA resulted in cell aggregation, biofilm formation, and increased adhesion to human intestinal Caco-2 epithelial cells. Immunization of mice with folded, full-length, purified SadA elicited an IgG response which provided limited protection against bacterial challenge. When anti-SadA IgG titers were enhanced by administering alum-precipitated protein, a modest additional protection was afforded. Therefore, despite SadA having pleiotropic functions, it is not a dominant, protective antigen for antibody-mediated protection against Salmonella. PMID:21859856

Simultaneous Near-Infrared Radiant Heating and UV Radiation for Inactivating Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium in Powdered Red Pepper (Capsicum annuum L.)

PubMed Central

Ha, Jae-Won

2013-01-01

This study was conducted to investigate the efficacy of the simultaneous application of near-infrared (NIR) heating and UV irradiation for reducing populations of food-borne pathogens, including Salmonella enterica serovar Typhimurium and Escherichia coli O157:H7 in red pepper powder and to clarify the mechanisms of the lethal effect of the NIR-UV combined treatment. Also, the effect of the combination treatment on quality was determined by measuring changes in color and pungency constituents. Simultaneous NIR-UV combined treatment for 5 min achieved 3.34- and 2.78-log CFU reductions in S. Typhimurium and E. coli O157:H7, respectively, which involved 1.86- and 1.31-log CFU reductions, respectively, which were attributed to the synergistic effect. Through qualitative and quantitative analyses, damage to the cell envelope was identified as the main factor contributing to the synergistic lethal effect of NIR-UV combined treatment. Color values and capsaicin and dihydrocapsaicin content of NIR-UV simultaneously treated red pepper powder were not significantly (P > 0.05) different from those of untreated samples. These results suggest that simultaneous application of NIR and UV treatment can be effectively used to control food-borne pathogens in powdered red pepper without affecting quality. PMID:23956394

Simultaneous near-infrared radiant heating and UV radiation for inactivating Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in powdered red pepper (Capsicum annuum L.).

PubMed

Ha, Jae-Won; Kang, Dong-Hyun

2013-11-01

This study was conducted to investigate the efficacy of the simultaneous application of near-infrared (NIR) heating and UV irradiation for reducing populations of food-borne pathogens, including Salmonella enterica serovar Typhimurium and Escherichia coli O157:H7 in red pepper powder and to clarify the mechanisms of the lethal effect of the NIR-UV combined treatment. Also, the effect of the combination treatment on quality was determined by measuring changes in color and pungency constituents. Simultaneous NIR-UV combined treatment for 5 min achieved 3.34- and 2.78-log CFU reductions in S. Typhimurium and E. coli O157:H7, respectively, which involved 1.86- and 1.31-log CFU reductions, respectively, which were attributed to the synergistic effect. Through qualitative and quantitative analyses, damage to the cell envelope was identified as the main factor contributing to the synergistic lethal effect of NIR-UV combined treatment. Color values and capsaicin and dihydrocapsaicin content of NIR-UV simultaneously treated red pepper powder were not significantly (P > 0.05) different from those of untreated samples. These results suggest that simultaneous application of NIR and UV treatment can be effectively used to control food-borne pathogens in powdered red pepper without affecting quality.

Rapid DNA transformation in Salmonella Typhimurium by the hydrogel exposure method.

PubMed

Elabed, Hamouda; Hamza, Rim; Bakhrouf, Amina; Gaddour, Kamel

2016-07-01

Even with advances in molecular cloning and DNA transformation, new or alternative methods that permit DNA penetration in Salmonella enterica subspecies enterica serovar Typhimurium are required in order to use this pathogen in biotechnological or medical applications. In this work, an adapted protocol of bacterial transformation with plasmid DNA based on the "Yoshida effect" was applied and optimized on Salmonella enterica serovar Typhimurium LT2 reference strain. The plasmid transference based on the use of sepiolite as acicular materials to promote cell piercing via friction forces produced by spreading on the surface of a hydrogel. The transforming mixture containing sepiolite nanofibers, bacterial cells to be transformed and plasmid DNA were plated directly on selective medium containing 2% agar. In order to improve the procedure, three variables were tested and the transformation of Salmonella cells was accomplished using plasmids pUC19 and pBR322. Using the optimized protocol on Salmonella LT2 strain, the efficiency was about 10(5) transformed cells per 10(9) subjected to transformation with 0.2μg plasmid DNA. In summary, the procedure is fast, offers opportune efficiency and promises to become one of the widely used transformation methods in laboratories. Copyright © 2016 Elsevier B.V. All rights reserved.

In Vivo Visualization of Bacterial Colonization, Antigen Expression, and Specific T-Cell Induction following Oral Administration of Live Recombinant Salmonella enterica Serovar Typhimurium

PubMed Central

Bumann, Dirk

2001-01-01

Live attenuated Salmonella strains that express a foreign antigen are promising oral vaccine candidates. Numerous genetic modifications have been empirically tested, but their effects on immunogenicity are difficult to interpret since important in vivo properties of recombinant Salmonella strains such as antigen expression and localization are incompletely characterized and the crucial early inductive events of an immune response to the foreign antigen are not fully understood. Here, methods were developed to directly localize and quantitate the in situ expression of an ovalbumin model antigen in recombinant Salmonella enterica serovar Typhimurium using two-color flow cytometry and confocal microscopy. In parallel, the in vivo activation, blast formation, and division of ovalbumin-specific CD4+ T cells were followed using a well-characterized transgenic T-cell receptor mouse model. This combined approach revealed a biphasic induction of ovalbumin-specific T cells in the Peyer's patches that followed the local ovalbumin expression of orally administered recombinant Salmonella cells in a dose- and time-dependent manner. Interestingly, intact Salmonella cells and cognate T cells seemed to remain in separate tissue compartments throughout induction, suggesting a transport of killed Salmonella cells from the colonized subepithelial dome area to the interfollicular inductive sites. The findings of this study will help to rationally optimize recombinant Salmonella strains as efficacious live antigen carriers for oral vaccination. PMID:11402006

Influence of rpoS mutations on the response of Salmonella enterica serovar Typhimurium to solar radiation.

PubMed

Oppezzo, Oscar J; Costa, Cristina S; Pizarro, Ramón A

2011-01-10

Salmonella enterica serovar Typhimurium is an important pathogen, and exhibits considerable resistance to the lethal effects of solar radiation. To evaluate the involvement of the RpoS transcription factor in the defense mechanisms of this organism, the sunlight response of a wild type strain (ATCC14028) was compared with that of an rpoS mutant, which exhibited increased sensitivity. Kinetics of cell death was complex in both strains, probably due to the presence of a variety of targets for the radiation. When ultraviolet radiation was excluded from the incident sunlight, lethal effects were abolished independently of the allelic state of rpoS. Reduction of oxygen concentration in the irradiation medium provided moderate protection to ATCC14028, but notably improved survival of the mutant. Similar assays were developed with another S. enterica strain (DA1468), which is a derivative of strain LT2 and produces low levels of RpoS. In this strain the loss of viability reveals the dependence on solar ultraviolet and oxygen concentration found for ATCC14028, but radiation resistance was slightly reduced. Increased sensitivity was observed in an rpoS mutant derived from DA1468, indicating that RpoS functions related to photoprotection are conserved in this strain. In addition, notable differences in the shape of the survival curves obtained for mutants derived from ATCC14028 and DA1468 were found, suggesting that genes beyond RpoS control are relevant in the sunlight response of these mutants. Copyright © 2010 Elsevier B.V. All rights reserved.

Immunogenicity of Recombinant Proteins Consisting of Plasmodium vivax Circumsporozoite Protein Allelic Variant-Derived Epitopes Fused with Salmonella enterica Serovar Typhimurium Flagellin

PubMed Central

Leal, Monica Teixeira Andrade; Camacho, Ariane Guglielmi Ariza; Teixeira, Laís Helena; Bargieri, Daniel Youssef; Soares, Irene Silva; Tararam, Cibele Aparecida

2013-01-01

A Plasmodium falciparum circumsporozoite protein (CSP)-based recombinant fusion vaccine is the first malaria vaccine to reach phase III clinical trials. Resistance to infection correlated with the production of antibodies to the immunodominant central repeat region of the CSP. In contrast to P. falciparum, vaccine development against the CSP of Plasmodium vivax malaria is far behind. Based on this gap in our knowledge, we generated a recombinant chimeric protein containing the immunodominant central repeat regions of the P. vivax CSP fused to Salmonella enterica serovar Typhimurium-derived flagellin (FliC) to activate the innate immune system. The recombinant proteins that were generated contained repeat regions derived from each of the 3 different allelic variants of the P. vivax CSP or a fusion of regions derived from each of the 3 allelic forms. Mice were subcutaneously immunized with the fusion proteins alone or in combination with the Toll-like receptor 3 (TLR-3) agonist poly(I·C), and the anti-CSP serum IgG response was measured. Immunization with a mixture of the 3 recombinant proteins, each containing immunodominant epitopes derived from a single allelic variant, rather than a single recombinant protein carrying a fusion of regions derived from each of 3 allelic forms elicited a stronger immune response. This response was independent of TLR-4 but required TLR-5/MyD88 activation. Antibody titers significantly increased when poly(I·C) was used as an adjuvant with a mixture of the 3 recombinant proteins. These recombinant fusion proteins are novel candidates for the development of an effective malaria vaccine against P. vivax. PMID:23863502

Sub-Inhibitory Concentrations of the Antibiotic Florfenicol Reduces Invasion in Isolates of Multi-Drug Resistant Salmonella Typhimurium DT104

USDA-ARS?s Scientific Manuscript database

Virulence can be enhanced in certain bacteria that are exposed to sub-lethal levels of antibiotics. Salmonella enterica serovar Typhimurium DT104 is resistant to five different antibiotics, including florfenicol. Using real-time PCR and a tissue culture invasion assay, we investigated the impact of ...

Transposon Mutagenesis of Salmonella enterica Serovar Enteritidis Identifies Genes That Contribute to Invasiveness in Human and Chicken Cells and Survival in Egg Albumen

PubMed Central

Zhou, Xiaohui; Kim, Hye-Young; Call, Douglas R.; Guard, Jean

2012-01-01

Salmonella enterica serovar Enteritidis is an important food-borne pathogen, and chickens are a primary reservoir of human infection. While most knowledge about Salmonella pathogenesis is based on research conducted on Salmonella enterica serovar Typhimurium, S. Enteritidis is known to have pathobiology specific to chickens that impacts epidemiology in humans. Therefore, more information is needed about S. Enteritidis pathobiology in comparison to that of S. Typhimurium. We used transposon mutagenesis to identify S. Enteritidis virulence genes by assay of invasiveness in human intestinal epithelial (Caco-2) cells and chicken liver (LMH) cells and survival within chicken (HD-11) macrophages as a surrogate marker for virulence. A total of 4,330 transposon insertion mutants of an invasive G1 Nalr strain were screened using Caco-2 cells. This led to the identification of attenuating mutations in a total of 33 different loci, many of which include genes previously known to contribute to enteric infection (e.g., Salmonella pathogenicity island 1 [SPI-1], SPI-4, SPI-5, CS54, fliH, fljB, csgB, spvR, and rfbMN) in S. Enteritidis and other Salmonella serovars. Several genes or genomic islands that have not been reported previously (e.g., SPI-14, ksgA, SEN0034, SEN2278, and SEN3503) or that are absent in S. Typhimurium or in most other Salmonella serovars (e.g., pegD, SEN1152, SEN1393, and SEN1966) were also identified. Most mutants with reduced Caco-2 cell invasiveness also showed significantly reduced invasiveness in chicken liver cells and impaired survival in chicken macrophages and in egg albumen. Consequently, these genes may play an important role during infection of the chicken host and also contribute to successful egg contamination by S. Enteritidis. PMID:22988017

Factors affecting the excretion of GFP Salmonella enterica serovar typhimurium by adult house flies (Diptera: Muscidae; Musca domestica L.)

USDA-ARS?s Scientific Manuscript database

House flies harbor and disseminate food-borne pathogens. Salmonella Typhimurium (S. Typhimurium) is a zoonotic pathogen shed by livestock that causes gastroenteritis in humans. We previously demonstrated that GFP-S. Typhimurium fed to house flies persist in the digestive for 24h. The excretion dynam...

Three-dimensional tissue assemblies: novel models for the study of Salmonella enterica serovar Typhimurium pathogenesis

NASA Technical Reports Server (NTRS)

Nickerson, C. A.; Goodwin, T. J.; Terlonge, J.; Ott, C. M.; Buchanan, K. L.; Uicker, W. C.; Emami, K.; LeBlanc, C. L.; Ramamurthy, R.; Clarke, M. S.;

Three-Dimensional Tissue Assemblies: Novel Models for the Study of Salmonella enterica Serovar Typhimurium Pathogenesis

PubMed Central

Nickerson, Cheryl A.; Goodwin, Thomas J.; Terlonge, Jacqueline; Ott, C. Mark; Buchanan, Kent L.; Uicker, William C.; Emami, Kamal; LeBlanc, Carly L.; Ramamurthy, Rajee; Clarke, Mark S.; Vanderburg, Charles R.; Hammond, Timothy; Pierson, Duane L.

2001-01-01

The lack of readily available experimental systems has limited knowledge pertaining to the development of Salmonella-induced gastroenteritis and diarrheal disease in humans. We used a novel low-shear stress cell culture system developed at the National Aeronautics and Space Administration in conjunction with cultivation of three-dimensional (3-D) aggregates of human intestinal tissue to study the infectivity of Salmonella enterica serovar Typhimurium for human intestinal epithelium. Immunohistochemical characterization and microscopic analysis of 3-D aggregates of the human intestinal epithelial cell line Int-407 revealed that the 3-D cells more accurately modeled human in vivo differentiated tissues than did conventional monolayer cultures of the same cells. Results from infectivity studies showed that Salmonella established infection of the 3-D cells in a much different manner than that observed for monolayers. Following the same time course of infection with Salmonella, 3-D Int-407 cells displayed minimal loss of structural integrity compared to that of Int-407 monolayers. Furthermore, Salmonella exhibited significantly lower abilities to adhere to, invade, and induce apoptosis of 3-D Int-407 cells than it did for infected Int-407 monolayers. Analysis of cytokine expression profiles of 3-D Int-407 cells and monolayers following infection with Salmonella revealed significant differences in expression of interleukin 1α (IL-1α), IL-1β, IL-6, IL-1Ra, and tumor necrosis factor alpha mRNAs between the two cultures. In addition, uninfected 3-D Int-407 cells constitutively expressed higher levels of transforming growth factor β1 mRNA and prostaglandin E2 than did uninfected Int-407 monolayers. By more accurately modeling many aspects of human in vivo tissues, the 3-D intestinal cell model generated in this study offers a novel approach for studying microbial infectivity from the perspective of the host-pathogen interaction. PMID:11598087

Inactivation of Salmonella Senftenberg, Salmonella Typhimurium and Salmonella Tennessee in peanut butter by 915 MHz microwave heating.

PubMed

Song, Won-Jae; Kang, Dong-Hyun

2016-02-01

This study evaluated the efficacy of a 915 MHz microwave with 3 different levels to inactivate 3 serovars of Salmonella in peanut butter. Peanut butter inoculated with Salmonella enterica serovar Senftenberg, S. enterica serovar Typhimurium and S. enterica serovar Tennessee were treated with a 915 MHz microwave with 2, 4 and 6 kW and acid and peroxide values and color changes were determined after 5 min of microwave heating. Salmonella populations were reduced with increasing treatment time and treatment power. Six kW 915 MHz microwave treatment for 5 min reduced these three Salmonella serovars by 3.24-4.26 log CFU/g. Four and two kW 915 MHz microwave processing for 5 min reduced these Salmonella serovars by 1.14-1.48 and 0.15-0.42 log CFU/g, respectively. Microwave treatment did not affect acid, peroxide, or color values of peanut butter. These results demonstrate that 915 MHz microwave processing can be used as a control method for reducing Salmonella in peanut butter without producing quality deterioration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of farm type on within-herd Salmonella prevalence, serovar distribution, and antimicrobial resistance.

PubMed

Rasschaert, G; Michiels, J; Arijs, D; Wildemauwe, C; De Smet, S; Heyndrickx, M

2012-05-01

Salmonella represents a major challenge to the pig industry, as pork presents a risk for human salmonellosis. In this study, we have examined the effect of farm type on the prevalence of fattening pigs shedding Salmonella on 12 farms at risk for harboring Salmonella. On six open (grow-to-finish) and six closed (farrow-to-finish) farms, the prevalence of pigs shedding Salmonella was determined on two occasions approximately 2 months apart. The serovar, phage type, and antimicrobial resistance of the obtained Salmonella isolates were determined. On all farms, pigs shedding Salmonella were detected on at least one of the two sampling days. The mean within-herd prevalence was 7.8%. Closed farms were two times less likely to have pigs shedding Salmonella than open farms. On open farms, the odds of finding Salmonella shedding in pigs were 1.9 times higher when sampling was performed at slaughter age than when samples were taken halfway through the fattening period. Salmonella enterica serovar Typhimurium was the most predominant serotype, with a prevalence of 62 to 63% on both farm types. Of all the Salmonella Typhimurium isolates, 65% had the tetraresistant profile ASSuT (ampicillin, streptomycin, sulfonamide, and tetracycline) with or without additional resistance to trimethoprim-sulfonamide. Phage type DT120 seemed to be especially associated with this antimicrobial-resistant profile. The prevalence of Salmonella Typhimurium isolates showing resistance to ampicillin, streptomycin, tetracycline, sulfonamide, trimethoprim-sulfonamide, and lincomycin hydrochloride and spectinomycin sulfate tetrahydrate was significantly higher on open farms than on closed farms.

Discovery of Novel Secreted Virulence Factors from Salmonella enterica Serovar Typhimurium by Proteomic Analysis of Culture Supernatants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niemann, George; Brown, Roslyn N.; Gustin, Jean K.

The intracellular pathogen Salmonella enterica serovar Typhimurium is a leading cause of acute gastroenteritis in the world. This pathogen has two type-III secretion systems (TTSS) necessary for virulence that are encoded in Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) and are expressed during extracellular or intracellular infectious states, respectively, to deliver virulence factors (effectors) to the host cell cytoplasm. While many have been identified and at least partially characterized, the full repertoire of effectors has not been catalogued. In this mass spectrometry-based proteomics study, we identified effector proteins secreted under minimal acidic medium growth conditions that induced themore » SPI-2 TTSS and its effectors, and compared the secretome from the parent strain to the secretome from strains missing either essential (SsaK) or regulatory components (SsaL) of the SPI-2 secretion apparatus. We identified 75% of the known TTSS effector repertoire. Excluding translocon components, 95% of the known effectors were biased for identification in the ssaL mutant background, which demonstrated that SsaL regulates SPI-2 type III secretion. To confirm secretion to animal cells, we made translational fusions of several of the best candidates to the calmodulin-dependent adenylate cyclase of Bordetella pertussis and assayed cAMP levels of infected J774 macrophage-like cells. From these infected cells we identified six new TTSS effectors and two others that are secreted independent of TTSS. Our results substantiate reports of additional secretion systems encoded by Salmonella other than TTSS.« less

Interactions of Salmonella enterica Serovar Typhimurium and Pectobacterium carotovorum within a Tomato Soft Rot.

PubMed

George, Andrée S; Cox, Clayton E; Desai, Prerak; Porwollik, Steffen; Chu, Weiping; de Moraes, Marcos H; McClelland, Michael; Brandl, Maria T; Teplitski, Max

2018-03-01

Salmonella spp. are remarkably adaptable pathogens, and this adaptability allows these bacteria to thrive in a variety of environments and hosts. The mechanisms with which these pathogens establish within a niche amid the native microbiota remain poorly understood. Here, we aimed to uncover the mechanisms that enable Salmonella enterica serovar Typhimurium strain ATCC 14028 to benefit from the degradation of plant tissue by a soft rot plant pathogen, Pectobacterium carotovorum The hypothesis that in the soft rot, the liberation of starch (not utilized by P. carotovorum ) makes this polymer available to Salmonella spp., thus allowing it to colonize soft rots, was tested first and proven null. To identify the functions involved in Salmonella soft rot colonization, we carried out transposon insertion sequencing coupled with the phenotypic characterization of the mutants. The data indicate that Salmonella spp. experience a metabolic shift in response to the changes in the environment brought on by Pectobacterium spp. and likely coordinated by the csrBC small regulatory RNA. While csrBC and flhD appear to be of importance in the soft rot, the global two-component system encoded by barA sirA (which controls csrBC and flhDC under laboratory conditions) does not appear to be necessary for the observed phenotype. Motility and the synthesis of nucleotides and amino acids play critical roles in the growth of Salmonella spp. in the soft rot. IMPORTANCE Outbreaks of produce-associated illness continue to be a food safety concern. Earlier studies demonstrated that the presence of phytopathogens on produce was a significant risk factor associated with increased Salmonella carriage on fruits and vegetables. Here, we genetically characterize some of the requirements for interactions between Salmonella and phytobacteria that allow Salmonella spp. to establish a niche within an alternate host (tomato). Pathways necessary for nucleotide synthesis, amino acid synthesis, and motility

Interactions of Salmonella enterica Serovar Typhimurium and Pectobacterium carotovorum within a Tomato Soft Rot

PubMed Central

Cox, Clayton E.; Desai, Prerak; Porwollik, Steffen; Chu, Weiping; de Moraes, Marcos H.; McClelland, Michael; Brandl, Maria T.; Teplitski, Max

2017-01-01

ABSTRACT Salmonella spp. are remarkably adaptable pathogens, and this adaptability allows these bacteria to thrive in a variety of environments and hosts. The mechanisms with which these pathogens establish within a niche amid the native microbiota remain poorly understood. Here, we aimed to uncover the mechanisms that enable Salmonella enterica serovar Typhimurium strain ATCC 14028 to benefit from the degradation of plant tissue by a soft rot plant pathogen, Pectobacterium carotovorum. The hypothesis that in the soft rot, the liberation of starch (not utilized by P. carotovorum) makes this polymer available to Salmonella spp., thus allowing it to colonize soft rots, was tested first and proven null. To identify the functions involved in Salmonella soft rot colonization, we carried out transposon insertion sequencing coupled with the phenotypic characterization of the mutants. The data indicate that Salmonella spp. experience a metabolic shift in response to the changes in the environment brought on by Pectobacterium spp. and likely coordinated by the csrBC small regulatory RNA. While csrBC and flhD appear to be of importance in the soft rot, the global two-component system encoded by barA sirA (which controls csrBC and flhDC under laboratory conditions) does not appear to be necessary for the observed phenotype. Motility and the synthesis of nucleotides and amino acids play critical roles in the growth of Salmonella spp. in the soft rot. IMPORTANCE Outbreaks of produce-associated illness continue to be a food safety concern. Earlier studies demonstrated that the presence of phytopathogens on produce was a significant risk factor associated with increased Salmonella carriage on fruits and vegetables. Here, we genetically characterize some of the requirements for interactions between Salmonella and phytobacteria that allow Salmonella spp. to establish a niche within an alternate host (tomato). Pathways necessary for nucleotide synthesis, amino acid synthesis, and

Whole Genome Shotgun Analysis: the Resolving Power to Distinguish 2009 and 2010 Clinical Isolates of Salmonella Typhimurium Possessing the Same PFGE Type

USDA-ARS?s Scientific Manuscript database

Between 2009 and 2011, Salmonella enterica subsp. enterica serovar Typhimurium with the JPXX01.0014 pulse field gel electrophoresis (PFGE) type was isolated across the United States. The 2009 isolates were associated with an outbreak from an unidentified food source, while later isolates were linked...

Genotypic and phenotypic characterization of multidrug resistant Salmonella Typhimurium and Salmonella Kentucky strains recovered from chicken carcasses

PubMed Central

Grant, Ar’Quette; Choi, Seon Young; Alam, M. Samiul; Bell, Rebecca; Cavanaugh, Christopher; Balan, Kannan V.; Babu, Uma S.

2017-01-01

Abstract Salmonella Typhimurium is the leading cause of human non-typhoidal gastroenteritis in the US. S. Kentucky is one the most commonly recovered serovars from commercially processed poultry carcasses. This study compared the genotypic and phenotypic properties of two Salmonella enterica strains Typhimurium (ST221_31B) and Kentucky (SK222_32B) recovered from commercially processed chicken carcasses using whole genome sequencing, phenotype characterizations and an intracellular killing assay. Illumina MiSeq platform was used for sequencing of two Salmonella genomes. Phylogenetic analysis employing homologous alignment of a 1,185 non-duplicated protein-coding gene in the Salmonella core genome demonstrated fully resolved bifurcating patterns with varying levels of diversity that separated ST221_31B and SK222_32B genomes into distinct monophyletic serovar clades. Single nucleotide polymorphism (SNP) analysis identified 2,432 (ST19) SNPs within 13 Typhimurium genomes including ST221_31B representing Sequence Type ST19 and 650 (ST152) SNPs were detected within 13 Kentucky genomes including SK222_32B representing Sequence Type ST152. In addition to serovar-specific conserved coding sequences, the genomes of ST221_31B and SK222_32B harbor several genomic regions with significant genetic differences. These included phage and phage-like elements, carbon utilization or transport operons, fimbriae operons, putative membrane associated protein-encoding genes, antibiotic resistance genes, siderophore operons, and numerous hypothetical protein-encoding genes. Phenotype microarray results demonstrated that ST221_31B is capable of utilizing certain carbon compounds more efficiently as compared to SK222_3B; namely, 1,2-propanediol, M-inositol, L-threonine, α-D-lactose, D-tagatose, adonitol, formic acid, acetoacetic acid, and L-tartaric acid. ST221_31B survived for 48 h in macrophages, while SK222_32B was mostly eliminated. Further, a 3-fold growth of ST221_31B was observed at

Genotypic and phenotypic characterization of multidrug resistant Salmonella Typhimurium and Salmonella Kentucky strains recovered from chicken carcasses.

PubMed

Tasmin, Rizwana; Hasan, Nur A; Grim, Christopher J; Grant, Ar'Quette; Choi, Seon Young; Alam, M Samiul; Bell, Rebecca; Cavanaugh, Christopher; Balan, Kannan V; Babu, Uma S; Parveen, Salina

2017-01-01

Salmonella Typhimurium is the leading cause of human non-typhoidal gastroenteritis in the US. S. Kentucky is one the most commonly recovered serovars from commercially processed poultry carcasses. This study compared the genotypic and phenotypic properties of two Salmonella enterica strains Typhimurium (ST221_31B) and Kentucky (SK222_32B) recovered from commercially processed chicken carcasses using whole genome sequencing, phenotype characterizations and an intracellular killing assay. Illumina MiSeq platform was used for sequencing of two Salmonella genomes. Phylogenetic analysis employing homologous alignment of a 1,185 non-duplicated protein-coding gene in the Salmonella core genome demonstrated fully resolved bifurcating patterns with varying levels of diversity that separated ST221_31B and SK222_32B genomes into distinct monophyletic serovar clades. Single nucleotide polymorphism (SNP) analysis identified 2,432 (ST19) SNPs within 13 Typhimurium genomes including ST221_31B representing Sequence Type ST19 and 650 (ST152) SNPs were detected within 13 Kentucky genomes including SK222_32B representing Sequence Type ST152. In addition to serovar-specific conserved coding sequences, the genomes of ST221_31B and SK222_32B harbor several genomic regions with significant genetic differences. These included phage and phage-like elements, carbon utilization or transport operons, fimbriae operons, putative membrane associated protein-encoding genes, antibiotic resistance genes, siderophore operons, and numerous hypothetical protein-encoding genes. Phenotype microarray results demonstrated that ST221_31B is capable of utilizing certain carbon compounds more efficiently as compared to SK222_3B; namely, 1,2-propanediol, M-inositol, L-threonine, α-D-lactose, D-tagatose, adonitol, formic acid, acetoacetic acid, and L-tartaric acid. ST221_31B survived for 48 h in macrophages, while SK222_32B was mostly eliminated. Further, a 3-fold growth of ST221_31B was observed at 24 hours

Effect of drinking-water administration of experimental chlorate ion preparations on Salmonella enterica serovar Typhimurium colonization in weaned and finished pigs.

PubMed

Anderson, R C; Hume, M E; Genovese, K J; Callaway, T R; Jung, Y S; Edrington, T S; Poole, T L; Harvey, R B; Bischoff, K M; Nisbet, D J

2004-04-01

Foodborne disease caused by Salmonella is of public health and economic significance. In order to assess the practical effectiveness of a new intervention strategy, experimental chlorate preparations (ECP) were administered via the drinking water to weaned and finished pigs that had been orally challenged the previous day with 10(9)-10(10) colony-forming units of Salmonella serovar Typhimurium. After 24 or 36 h ad libitum access to 0X, 1X or 2X ECP treatment (where X is the concentration estimated to deliver a minimal daily effective dose), the pigs were euthanized and gut contents and lymph tissue collected at necropsy were cultured for the challenge Salmonella. Drinking water administration of ECP effectively reduced (p < 0.05) caecal Salmonella concentrations and, with the weaned pigs, tended (p < or = 0.10) to reduce rectal Salmonella concentrations. No negative effects of ECP treatment on water intake and animal wellbeing were observed and only marginal effects on gut fermentation characteristics occurred. The bactericidal effect of administering ECP in drinking water was relatively rapid, with reductions in caecal Salmonella concentrations occurring within 24 h. These results suggest that ECP administered to pigs just days before slaughter may reduce gut concentrations of Salmonella; however, the impacts of such reductions on slaughter hygiene have yet to be determined.

Association of virulence plasmid and antibiotic resistance determinants with chromosomal multilocus genotypes in Mexican Salmonella enterica serovar Typhimurium strains

PubMed Central

2009-01-01

Background Bacterial genomes are mosaic structures composed of genes present in every strain of the same species (core genome), and genes present in some but not all strains of a species (accessory genome). The aim of this study was to compare the genetic diversity of core and accessory genes of a Salmonella enterica subspecies enterica serovar Typhimurium (Typhimurium) population isolated from food-animal and human sources in four regions of Mexico. Multilocus sequence typing (MLST) and macrorestriction fingerprints by pulsed-field gel electrophoresis (PFGE) were used to address the core genetic variation, and genes involved in pathogenesis and antibiotic resistance were selected to evaluate the accessory genome. Results We found a low genetic diversity for both housekeeping and accessory genes. Sequence type 19 (ST19) was supported as the founder genotype of STs 213, 302 and 429. We found a temporal pattern in which the derived ST213 is replacing the founder ST19 in the four geographic regions analyzed and a geographic trend in the number of resistance determinants. The distribution of the accessory genes was not random among chromosomal genotypes. We detected strong associations among the different accessory genes and the multilocus chromosomal genotypes (STs). First, the Salmonella virulence plasmid (pSTV) was found mostly in ST19 isolates. Second, the plasmid-borne betalactamase cmy-2 was found only in ST213 isolates. Third, the most abundant integron, IP-1 (dfrA12, orfF and aadA2), was found only in ST213 isolates. Fourth, the Salmonella genomic island (SGI1) was found mainly in a subgroup of ST19 isolates carrying pSTV. The mapping of accessory genes and multilocus genotypes on the dendrogram derived from macrorestiction fingerprints allowed the establishment of genetic subgroups within the population. Conclusion Despite the low levels of genetic diversity of core and accessory genes, the non-random distribution of the accessory genes across chromosomal

Isolation and characterization of polyvalent bacteriophages infecting multi drug resistant Salmonella serovars isolated from broilers in Egypt.

PubMed

Mahmoud, Mayada; Askora, Ahmed; Barakat, Ahmed Barakat; Rabie, Omar El-Farouk; Hassan, Sayed Emam

2018-02-02

In this study, we isolated and characterized three phages named as Salmacey1, Salmacey2 and Salmacey3, infecting multi drug resistant Salmonella serovars isolated from broilers in Egypt. The most prevalent Salmonella serovars were S. typhimurium, S. enteritidis, and S. kentucky. All these Salmonella serovars were found to be resistant to more than two of the ten antimicrobial agents tested. Only S. kentucky was found to be resistant to seven antimicrobial agents. Examination of these phage particles by transmission electron microscopy (TEM), demonstrated that two phages (Salmacey1, Salmacey2) were found to belong to family Siphoviridae, and Salmacey3 was assigned to the family Myoviridae. The results of host range assay revealed that these bacteriophages were polyvalent and thus capable of infecting four strains of Salmonella serovars and Citrobacter freundii. Moreover, the two phages (Salmacey1, Salmacey2) had a lytic effect on Enterobacter cloacae and Salmacey3 was able to infect E. coli. All phages could not infect S. para Typhi, Staphylococus aureus and Bacillus cereus. One-step growth curves of bacteriophages revealed that siphovirus phages (Salmacey1, Salmacey2) have burst size (80 and 90pfu per infected cell with latent period 35min and 40min respectively), and for the myovirus Salmacey3 had a burst size 110pfu per infected cell with latent period 60min. Molecular analyses indicated that these phages contained double-stranded DNA genomes. The lytic activity of the phages against the most multidrug resistant serovars S. kentucky as host strain was evaluated. The result showed that these bacteriophages were able to completely stop the growth of S. kentucky in vitro. These results suggest that phages have a high potential for phage application to control Salmonella serovars isolated from broilers in Egypt. Copyright © 2017. Published by Elsevier B.V.

Effect of age on susceptibility to Salmonella Typhimurium infection in C57BL/6 mice.

PubMed

Ren, Zhihong; Gay, Raina; Thomas, Adam; Pae, Munkyong; Wu, Dayong; Logsdon, Lauren; Mecsas, Joan; Meydani, Simin Nikbin

2009-12-01

Ageing is associated with a decline in immune function, which predisposes the elderly to a higher incidence of infections. Information on the mechanism of the age-related increase in susceptibility to Salmonella enterica serovar Typhimurium (S. Typhimurium) is limited. In particular, little is known regarding the involvement of the immune response in this age-related change. We employed streptomycin (Sm)-pretreated C57BL/6 mice to develop a mouse model that would demonstrate age-related differences in susceptibility and immune response to S. Typhimurium. In this model, old mice inoculated orally with doses of 3 x 10(8) or 1 x 10(6) c.f.u. S. Typhimurium had significantly greater S. Typhimurium colonization in the ileum, colon, Peyer's patches, spleen and liver than young mice. Old mice had significantly higher weight loss than young mice on days 1 and 2 post-infection. In response to S. Typhimurium infection, old mice failed to increase ex vivo production of IFN-gamma and TNF-alpha in the spleen and mesenteric lymph node cells to the same degree as observed in young mice; this was associated with their inability to maintain the presence of neutrophils and macrophages at a 'youthful' level. These results indicate that Sm-pretreated C57BL/6 old mice are more susceptible to S. Typhimurium infection than young mice, which might be due to impaired IFN-gamma and TNF-alpha production as well as a corresponding change in the number of neutrophils and macrophages in response to S. Typhimurium infection compared to young mice.

Immunochromatographic strip assay for the rapid and sensitive detection of Salmonella Typhimurium in artificially contaminated tomato samples.

PubMed

Shukla, Shruti; Leem, Hyerim; Lee, Jong-Suk; Kim, Myunghee

2014-06-01

This study was designed to confirm the applicability of a liposome-based immunochromatographic assay for the rapid detection of Salmonella enterica subsp. enterica serovar Typhimurium (Salmonella Typhimurium) in artificially contaminated tomato samples. To determine the detection limit and pre-enrichment incubation time (10, 12, and 18 h pre-enrichment in 1% buffered peptone water), the tests were performed with different cell numbers of Salmonella Typhimurium (3 × 10(0), 3 × 10(1), 3 × 10(2), and 3 × 10(3) CFU·mL(-1)) inoculated into 25 g of crushed tomato samples. The assay was able to detect as few as 30 Salmonella Typhimurium cells per 25 g of tomato samples (1.2 cells·g(-1)) after 12 h pre-enrichment incubation. Moreover, when the developed assay was compared with traditional morphological and biochemical culture-based methods as well as colloidal gold nanoparticle-based commercial test strips, the developed assay yielded positive results for the detection of Salmonella Typhimurium within a shorter period time. These findings confirm that the developed assay may have practical application for the sensitive detection of Salmonella Typhimurium in various food samples, including raw vegetables, with a relatively low detection limit and shorter analysis time.

Effect of Egg Washing and Correlation between Eggshell Characteristics and Egg Penetration by Various Salmonella Typhimurium Strains

PubMed Central

Gole, Vaibhav C.; Chousalkar, Kapil K.; Roberts, Juliet R.; Sexton, Margaret; May, Damian; Tan, Jessica; Kiermeier, Andreas

2014-01-01

Salmonella is an important foodborne pathogen, causing an estimated 11,992 cases of infection in Australia per year. Egg or egg product related salmonellosis is a major concern for the egg industry. Worldwide, S. Typhimurium is one of the most common serovars identified in Salmonella food poisoning cases. The current study investigated the ability of five S. Typhimurium strains to penetrate washed and unwashed eggs using whole egg and agar egg penetration methods. All S. Typhimurium strains were able to penetrate eggshells and survive in egg albumen (at 20°C) according to whole egg penetration results. Polymerase Chain Reaction results demonstrated that S. Typhimurium strain 2 (103 and 105 CFU/mL), and strain 5 (103 and 105 CFU/mL) egg penetration was significantly higher (p<0.05) in washed eggs when compared to unwashed eggs. Statistical analysis of the agar penetration experiment indicated that S. Typhimurium was able to penetrate washed eggs at a significantly higher rate when compared to unwashed eggs (p<0.05). When compared to unwashed eggs, washed eggs also had significantly damaged cuticles. Statistical analysis also indicated that eggshell penetration by S. Typhimurium was related to various eggshell ultrastructural features such as cap quality, alignment, erosion, confluence, Type B bodies and cuticle cover. PMID:24621821

Prevalence and Characterization of Monophasic Salmonella Serovar 1,4,[5],12:i:- of Food Origin in China.

PubMed

Yang, Xiaojuan; Wu, Qingping; Zhang, Jumei; Huang, Jiahui; Guo, Weipeng; Cai, Shuzhen

2015-01-01

Salmonella enterica subsp. enterica serovar 1,4,[5],12:i:- is a monophasic variant of Salmonella Typhimurium, which has recently been recognized as an emerging cause of infection worldwide. This bacterium has also ranked among the four most frequent serovars causing human salmonellosis in China. However, there are no reports on its contamination in Chinese food. Serotyping, polymerase chain reaction, antibiotic resistance, virulotyping, and multilocus sequence typing (MLST) assays were used to investigate the prevalence of this serological variant in food products in China, and to determine phenotypic and genotypic difference of monophasic isolates and Salmonella Typhimurium isolated over the same period. Salmonella 1,4,[5],12:i:- was prevalent in various food sources, including beef, pork, chicken, and pigeon. The study also confirmed the high prevalence (53.8%) of resistance to ampicillin, streptomycin, sulfonamides, and tetracycline in Salmonella 1,4,[5],12:i:-, which was higher than that in Salmonella Typhimurium. Moreover, Salmonella 1,4,[5],12:i:- isolates in our study were different from Salmonella Typhimurium isolates by the absence of three plasmid-borne genes (spvC, pefA, and rck) and the presence of gipA in all isolates. All Salmonella 1,4,[5],12:i:- isolates demonstrated MLST pattern ST34. Genomic deletions within the fljBA operon and surrounding genes were only found in Salmonella 1,4,[5],12:i:- isolates, with all isolates containing a deletion of fljB. However, hin and iroB were identified in all Salmonella 1,4,[5],12:i:- isolates. Three different deletion profiles were observed and two of them were different from the reported Salmonella 1,4,[5],12:i:- clones from Spain, America, and Italy, which provided some new evidence on the independent evolution of the multiple successful monophasic clones from Salmonella Typhimurium ancestors. This study is the first report of Salmonella 1,4,[5],12:i:- in food products from China. The data are more

Prevalence and Characterization of Monophasic Salmonella Serovar 1,4,[5],12:i:- of Food Origin in China

PubMed Central

Yang, Xiaojuan; Wu, Qingping; Zhang, Jumei; Huang, Jiahui; Guo, Weipeng; Cai, Shuzhen

2015-01-01

Salmonella enterica subsp. enterica serovar 1,4,[5],12:i:- is a monophasic variant of Salmonella Typhimurium, which has recently been recognized as an emerging cause of infection worldwide. This bacterium has also ranked among the four most frequent serovars causing human salmonellosis in China. However, there are no reports on its contamination in Chinese food. Serotyping, polymerase chain reaction, antibiotic resistance, virulotyping, and multilocus sequence typing (MLST) assays were used to investigate the prevalence of this serological variant in food products in China, and to determine phenotypic and genotypic difference of monophasic isolates and Salmonella Typhimurium isolated over the same period. Salmonella 1,4,[5],12:i:- was prevalent in various food sources, including beef, pork, chicken, and pigeon. The study also confirmed the high prevalence (53.8%) of resistance to ampicillin, streptomycin, sulfonamides, and tetracycline in Salmonella 1,4,[5],12:i:-, which was higher than that in Salmonella Typhimurium. Moreover, Salmonella 1,4,[5],12:i:- isolates in our study were different from Salmonella Typhimurium isolates by the absence of three plasmid-borne genes (spvC, pefA, and rck) and the presence of gipA in all isolates. All Salmonella 1,4,[5],12:i:- isolates demonstrated MLST pattern ST34. Genomic deletions within the fljBA operon and surrounding genes were only found in Salmonella 1,4,[5],12:i:- isolates, with all isolates containing a deletion of fljB. However, hin and iroB were identified in all Salmonella 1,4,[5],12:i:- isolates. Three different deletion profiles were observed and two of them were different from the reported Salmonella 1,4,[5],12:i:- clones from Spain, America, and Italy, which provided some new evidence on the independent evolution of the multiple successful monophasic clones from Salmonella Typhimurium ancestors. This study is the first report of Salmonella 1,4,[5],12:i:- in food products from China. The data are more

Characterization and Antimicrobial Resistance of Salmonella Typhimurium Isolates from Clinically Diseased Pigs in Korea.

PubMed

Oh, Sang-Ik; Kim, Jong Wan; Chae, Myeongju; Jung, Ji-A; So, Byungjae; Kim, Bumseok; Kim, Ha-Young

2016-11-01

This study investigated the prevalence of Salmonella enterica serovar and antimicrobial resistance in Salmonella Typhimurium isolates from clinically diseased pigs collected from 2008 to 2014 in Korea. Isolates were also characterized according to the presence of antimicrobial resistance genes and pulsed-field gel electrophoresis patterns. Among 94 Salmonella isolates, 81 (86.2%) were identified as being of the Salmonella Typhimurium serotype, followed by Salmonella Derby (6 of 94, 6.4%), Salmonella 4,[5],12:i:- (4 of 94, 4.3%), Salmonella Enteritidis (2 of 94, 2.1%), and Salmonella Brandenburg (1 of 94, 1.1%). The majority of Salmonella Typhimurium isolates were resistant to tetracycline (92.6%), followed by streptomycin (88.9%) and ampicillin (80.2%). Overall, 96.3% of Salmonella Typhimurium isolates showed multidrug-resistant phenotypes and commonly harbored the resistance genes bla TEM (64.9%), flo (32.8%), aadA (55.3%), strA (58.5%), strB (58.5%), sulII (53.2%), and tetA (61.7%). The pulsed-field gel electrophoresis analysis of 45 Salmonella Typhimurium isolates from individual farms revealed 27 distinct patterns that formed one major and two minor clusters in the dendrogram analysis, suggesting that most of the isolates (91.1%) from diseased pigs were genetically related. These findings can assist veterinarians in the selection of appropriate antimicrobial agents to combat Salmonella Typhimurium infections in pigs. Furthermore, they highlight the importance of continuous surveillance of antimicrobial resistance and genetic status in Salmonella Typhimurium for the detection of emerging resistance trends.

Resistance to essential oils affects survival of Salmonella enterica serovars in growing and harvested basil.

PubMed

Kisluk, Guy; Kalily, Emmanuel; Yaron, Sima

2013-10-01

The number of outbreaks of food-borne illness associated with consumption of fresh products has increased. A recent and noteworthy outbreak occurred in 2007. Basil contaminated with Salmonella enterica serovar Senftenberg was the source of this outbreak. Since basil produces high levels of antibacterial compounds the aim of this study was to investigate if the emerging outbreak reflects ecological changes that occurred as a result of development of resistance to ingredients of the basil oil. We irrigated basil plants with contaminated water containing two Salmonella serovars, Typhimurium and Senftenberg, and showed that Salmonella can survive on the basil plants for at least 100 days. S. Senftenberg counts in the phyllosphere were significantly higher than S. Typhimurium, moreover, S. Senftenberg was able to grow on stored harvested basil leaves. Susceptibility experiments demonstrated that S. Senftenberg is more resistant to basil oil and to its antimicrobial constituents: linalool, estragole and eugenol. This may indicate that S. Senftenberg had adapted to the basil environment by developing resistance to the basil oil. The emergence of resistant pathogens has a significant potential to change the ecology, and opens the way for pathogens to survive in new niches in the environment such as basil and other plants. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

Host Hydrogen Rather than That Produced by the Pathogen Is Important for Salmonella enterica Serovar Typhimurium Virulence

PubMed Central

Lamichhane-Khadka, Reena; Benoit, Stéphane L.; Miller-Parks, Erica F.

2014-01-01

Salmonella enterica serovar Typhimurium utilizes molecular hydrogen as a substrate in various respiratory pathways, via H2-uptake enzymes termed Hya, Hyb, and Hyd. A different hydrogenase, the hydrogen-evolving Hyc enzyme, removes excess reductant during fermentative growth. Virulence phenotypes conferred by mutations in hyc genes, either alone or in combination with mutations in the H2-uptake enzyme genes, are addressed. Anaerobically grown ΔhycB or ΔhycC single-deletion strains were more sensitive to acid than the wild-type strain, but the Δhyc strains were like the virulent parent strain with respect to both mouse morbidity and mortality and in organ burden numbers. Even fecal-recovery numbers for both mutant strains at several time points prior to the animals succumbing to salmonellosis were like those seen with the parent. Neither hydrogen uptake nor evolution of the gas was detected in a hydrogenase quadruple-mutant strain containing deletions in the hya, hyb, hyd, and hyc genes. As previously described, a strain lacking all H2-uptake ability was severely attenuated in its virulence characteristics, and the quadruple-mutant strain had the same (greatly attenuated) phenotype. While H2 levels were greatly reduced in ceca of mice treated with antibiotics, both the ΔhycB and ΔhycC strains were still like the parent in their ability to cause typhoid salmonellosis. It seems that the level of H2 produced by the pathogen (through formate hydrogen lyase [FHL] and Hyc) is insignificant in terms of providing respiratory reductant to facilitate either organ colonization or contributions to gut growth leading to pathogenesis. PMID:25368112

Characterization of a T7-like lytic bacteriophage (phiSG-JL2) of Salmonella enterica serovar gallinarum biovar gallinarum.

PubMed

Kwon, Hyuk-Joon; Cho, Sun-Hee; Kim, Tae-Eun; Won, Yong-Jin; Jeong, Jihye; Park, Se Chang; Kim, Jae-Hong; Yoo, Han-Sang; Park, Yong-Ho; Kim, Sun-Joong

2008-11-01

PhiSG-JL2 is a newly discovered lytic bacteriophage infecting Salmonella enterica serovar Gallinarum biovar Gallinarum but is nonlytic to a rough vaccine strain of serovar Gallinarum biovar Gallinarum (SG-9R), S. enterica serovar Enteritidis, S. enterica serovar Typhimurium, and S. enterica serovar Gallinarum biovar Pullorum. The phiSG-JL2 genome is 38,815 bp in length (GC content, 50.9%; 230-bp-long direct terminal repeats), and 55 putative genes may be transcribed from the same strand. Functions were assigned to 30 genes based on high amino acid similarity to known proteins. Most of the expected proteins except tail fiber (31.9%) and the overall organization of the genomes were similar to those of yersiniophage phiYeO3-12. phiSG-JL2 could be classified as a new T7-like virus and represents the first serovar Gallinarum biovar Gallinarum phage genome to be sequenced. On the basis of intraspecific ratios of nonsynonymous to synonymous nucleotide changes (Pi[a]/Pi[s]), gene 2 encoding the host RNA polymerase inhibitor displayed Darwinian positive selection. Pretreatment of chickens with phiSG-JL2 before intratracheal challenge with wild-type serovar Gallinarum biovar Gallinarum protected most birds from fowl typhoid. Therefore, phiSG-JL2 may be useful for the differentiation of serovar Gallinarum biovar Gallinarum from other Salmonella serotypes, prophylactic application in fowl typhoid control, and understanding of the vertical evolution of T7-like viruses.

Comparison of the activities of extracts of Escherichia coli and Salmonella typhimurium in amino acid incorporation.

PubMed

Bassel, B A; Curry, M E

1973-11-01

We have compared the amino acid incorporating activities of extracts of Escherichia coli and Salmonella typhimurium in in vitro protein-synthesizing systems directed by bacterial messenger ribonucleic acid (mRNA) of both species and by the genomes of coliphages Qbeta and f2. E. coli and S. typhimurium extracts translate both homologous and heterologous bacterial mRNAs at comparable rates. S. typhimurium extracts translate phage RNAs only 10 to 15% as fast as E. coli extracts do. The presence of glucose in the growth medium increases the activity of S. typhimurium extracts three- to fourfold in the phage RNA-directed systems. Glucose has a much more limited effect on the activities of E. coli extracts. We show that similar amounts of phage RNA-ribosome complexes are formed in both the E. coli and the S. typhimurium systems, indicating that the different activities observed may be attributed to different rates of peptide elongation or to the formation of complexes at different sites on the RNA strand.

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

PubMed Central

Johnson, Timothy J.; Ricke, Steven C.; Nayak, Rajesh; Danzeisen, Jessica

2013-01-01

SUMMARY Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S. Typhi, S. Dublin, and S. Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S. Enteritidis and S. Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S. Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S. Kentucky and S. Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today. PMID:24296573

Salmonella Typhimurium and Outbreaks of Egg-Associated Disease in Australia, 2001 to 2011.

PubMed

Moffatt, Cameron R M; Musto, Jennie; Pingault, Nevada; Miller, Megge; Stafford, Russell; Gregory, Joy; Polkinghorne, Benjamin G; Kirk, Martyn D

2016-07-01

Salmonellosis is a significant public health problem, with eggs frequently identified as a food vehicle during outbreak investigations. Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis are the two most frequently identified causes of egg-associated disease in industrialized countries. In Australia, a comprehensive review of egg-associated outbreaks has not been previously undertaken. Using a national register of foodborne outbreaks, we undertook a descriptive review of egg-associated outbreaks between 2001 and 2011. Included in our review was additional detail from the findings of trace back investigations conducted to the farm level. Evidence classifications were developed and applied to each outbreak based on descriptive and analytical epidemiology, food safety investigations, and microbiological testing of clinical, food, and trace back-derived samples. Over the study period, the proportion of foodborne Salmonella outbreaks linked to eggs increased significantly (p < 0.001). In total, 166 outbreaks were identified, with 90% caused by Salmonella Typhimurium. The majority of outbreaks were linked to commercial food providers, with raw egg use the major contributing factor. These events resulted in more than 3200 cases, more than 650 hospitalizations, and at least 4 deaths. Fifty-four percent of investigations used analytical epidemiology, food microbiology, and trace back microbiology to demonstrate links between human illness and eggs. Trace back investigations identified S. enterica indistinguishable from outbreak-associated clinical or food samples on 50% of sampled egg farms. Effective control of egg-associated salmonellosis remains a challenge in Australia, with Salmonella Typhimurium dominating as the causative serotype in outbreak events. Although outbreaks predominantly occur in the settings of restaurants, the high recovery rate of indistinguishable Salmonella on epidemiologically implicated egg farms suggests that

General response of Salmonella enterica serovar Typhimurium to desiccation: A new role for the virulence factors sopD and sseD in survival

PubMed Central

Maserati, Alice; Lourenco, Antonio; Julius, Matthew L.; Diez-Gonzalez, Francisco

2017-01-01

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 Salmonella’s 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 wild-type strain and to an E. coli O157:H7 strain. The sopD and sseD mutants exhibited significant cell viability reductions of 2.5 and 1.3 Log (CFU/g), respectively, compared to the wild-type after desiccation for 4 days on glass beads. Additional viability differences of the mutants were observed after exposure to aw 0.11 for 7 days. E. coli O157:H7 lost viability similarly to the mutants. Scanning electron microscopy showed that both mutants displayed a different morphology compared to the wild-type and differences in production of the extracellular matrix under the same conditions. These findings suggested that sopD and sseD are required for Salmonella’s survival during desiccation. PMID:29117268

Development of multiplex PCR assay for simultaneous detection of Salmonella genus, Salmonella subspecies I, Salm. Enteritidis, Salm. Heidelberg and Salm. Typhimurium.

PubMed

Park, S H; Ricke, S C

2015-01-01

The aim of this research was to develop multiplex PCR assay that could simultaneously detect Salmonella genus, Salmonella subsp. I, Salm. Enteritidis, Heidelberg and Typhimurium because these Salmonella serovars are the most common isolates associated with poultry products. Five primers were utilized to establish multiplex PCR and applied to Salmonella isolates from chickens and farm environments. These isolates were identified as Salmonella subsp. I and 16 of 66 isolates were classified as Salm. Enteritidis, while Heidelberg or Typhimurium was not detected. We also spiked three Salmonella strains on chicken breast meat to evaluate the specificity and sensitivity of multiplex PCR as well as qPCR to optimize quantification of Salmonella in these samples. The optimized multiplex PCR and qPCR could detect approx. 2·2 CFU of Salmonella per gram after 18 h enrichment. The multiplex PCR and qPCR would provide rapid and consistent results. Also, these techniques would be useful for the detection and quantification of Salmonella in contaminated poultry, foods and environmental samples. The strategy for the rapid detection of Salmonella serovars in poultry is needed to further reduce the incidence of salmonellosis in humans. The optimized multiplex PCR will be useful to detect prevalent Salmonella serovars in poultry products. © 2014 The Society for Applied Microbiology.

A community effort towards a knowledge-base and mathematical model of the human pathogen Salmonella Typhimurium LT2.

PubMed

Thiele, Ines; Hyduke, Daniel R; Steeb, Benjamin; Fankam, Guy; Allen, Douglas K; Bazzani, Susanna; Charusanti, Pep; Chen, Feng-Chi; Fleming, Ronan M T; Hsiung, Chao A; De Keersmaecker, Sigrid C J; Liao, Yu-Chieh; Marchal, Kathleen; Mo, Monica L; Özdemir, Emre; Raghunathan, Anu; Reed, Jennifer L; Shin, Sook-il; Sigurbjörnsdóttir, Sara; Steinmann, Jonas; Sudarsan, Suresh; Swainston, Neil; Thijs, Inge M; Zengler, Karsten; Palsson, Bernhard O; Adkins, Joshua N; Bumann, Dirk

2011-01-18

Metabolic reconstructions (MRs) are common denominators in systems biology and represent biochemical, genetic, and genomic (BiGG) knowledge-bases for target organisms by capturing currently available information in a consistent, structured manner. Salmonella enterica subspecies I serovar Typhimurium is a human pathogen, causes various diseases and its increasing antibiotic resistance poses a public health problem. Here, we describe a community-driven effort, in which more than 20 experts in S. Typhimurium biology and systems biology collaborated to reconcile and expand the S. Typhimurium BiGG knowledge-base. The consensus MR was obtained starting from two independently developed MRs for S. Typhimurium. Key results of this reconstruction jamboree include i) development and implementation of a community-based workflow for MR annotation and reconciliation; ii) incorporation of thermodynamic information; and iii) use of the consensus MR to identify potential multi-target drug therapy approaches. Taken together, with the growing number of parallel MRs a structured, community-driven approach will be necessary to maximize quality while increasing adoption of MRs in experimental design and interpretation.

A community effort towards a knowledge-base and mathematical model of the human pathogen Salmonella Typhimurium LT2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thiele, Ines; Hyduke, Daniel R.; Steeb, Benjamin

2011-01-01

Metabolic reconstructions (MRs) are common denominators in systems biology and represent biochemical, genetic, and genomic (BiGG) knowledge-bases for target organisms by capturing currently available information in a consistent, structured manner. Salmonella enterica subspecies I serovar Typhimurium is a human pathogen, causes various diseases and its increasing antibiotic resistance poses a public health problem. Here, we describe a community-driven effort, in which more than 20 experts in S. Typhimurium biology and systems biology collaborated to reconcile and expand the S. Typhimurium BiGG knowledge-base. The consensus MR was obtained starting from two independently developed MRs for S. Typhimurium. Key results of thismore » reconstruction jamboree include i) development and implementation of a community-based workflow for MR annotation and reconciliation; ii) incorporation of thermodynamic information; and iii) use of the consensus MR to identify potential multi-target drug therapy approaches. Finally, taken together, with the growing number of parallel MRs a structured, community-driven approach will be necessary to maximize quality while increasing adoption of MRs in experimental design and interpretation.« less

Modification of Enrofloxacin Treatment Regimens for Poultry Experimentally Infected with Salmonella enterica Serovar Typhimurium DT104 To Minimize Selection of Resistance▿

PubMed Central

Randall, Luke P.; Cooles, Sue W.; Coldham, Nick C.; Stapleton, Ken S.; Piddock, Laura J. V.; Woodward, Martin J.

2006-01-01

We hypothesized that higher doses of fluoroquinolones for a shorter duration could maintain efficacy (as measured by reduction in bacterial count) while reducing selection in chickens of bacteria with reduced susceptibility. Chicks were infected with Salmonella enterica serovar Typhimurium DT104 and treated 1 week later with enrofloxacin at the recommended dose for 5 days (water dose adjusted to give 10 mg/kg of body weight of birds or equivalence, i.e., water at 50 ppm) or at 2.5 or 5 times the recommended dose for 2 days or 1 day, respectively. The dose was delivered continuously (ppm) or pulsed in the water (mg/kg) or by gavage (mg/kg). In vitro in sera, increasing concentrations of 0.5 to 8 μg/ml enrofloxacin correlated with increased activity. In vivo, the efficacy of the 1-day treatment was significantly less than that of the 2- and 5-day treatments. The 2-day treatments showed efficacy similar to that of the 5-day treatment in all but one repeat treatment group and significantly (P < 0.01) reduced the Salmonella counts. Dosing at 2.5× the recommended dose and pulsed dosing both increased the peak antibiotic concentrations in cecal contents, liver, lung, and sera as determined by high-pressure liquid chromatography. There was limited evidence that shorter treatment regimens (in particular the 1-day regimen) selected for fewer strains with reduced susceptibility. In conclusion, the 2-day treatment would overall require a shorter withholding time than the 5-day treatment and, in view of the increased peak antibiotic concentrations, may give rise to improved efficacy, in particular for treating respiratory and systemic infections. However, it would be necessary to validate the 2-day regimen in a field situation and in particular against respiratory and systemic infections to validate or refute this hypothesis. PMID:17030564

Two Novel Salmonella Bivalent Vaccines Confer Dual Protection against Two Salmonella Serovars in Mice

PubMed Central

Zhao, Xinxin; Dai, Qinlong; Jia, Renyong; Zhu, Dekang; Liu, Mafeng; Wang, Mingshu; Chen, Shun; Sun, Kunfeng; Yang, Qiao; Wu, Ying; Cheng, Anchun

2017-01-01

Non-typhoidal Salmonella includes thousands of serovars that are leading causes of foodborne diarrheal illness worldwide. In this study, we constructed three bivalent vaccines for preventing both Salmonella Typhimurium and Salmonella Newport infections by using the aspartate semialdehyde dehydrogenase (Asd)-based balanced-lethal vector-host system. The constructed Asd+ plasmid pCZ11 carrying a subset of the Salmonella Newport O-antigen gene cluster including the wzx-wbaR-wbaL-wbaQ-wzy-wbaW-wbaZ genes was introduced into three Salmonella Typhimurium mutants: SLT19 (Δasd) with a smooth LPS phenotype, SLT20 (Δasd ΔrfbN) with a rough LPS phenotype, and SLT22 (Δasd ΔrfbN ΔpagL::T araC PBAD rfbN) with a smooth LPS phenotype when grown with arabinose. Immunoblotting demonstrated that SLT19 harboring pCZ11 [termed SLT19 (pCZ11)] co-expressed the homologous and heterologous O-antigens; SLT20 (pCZ11) exclusively expressed the heterologous O-antigen; and when arabinose was available, SLT22 (pCZ11) expressed both types of O-antigens, while in the absence of arabinose, SLT22 (pCZ11) expressed only the heterologous O-antigen. Exclusive expression of the heterologous O-antigen in Salmonella Typhimurium decreased the swimming ability of the bacterium and its susceptibility to polymyxin B. Next, the crp gene was deleted from the three recombinant strains for attenuation purposes, generating the three bivalent vaccine strains SLT25 (pCZ11), SLT26 (pCZ11), and SLT27 (pCZ11), respectively. Groups of BALB/c mice (12 mice/group) were orally immunized with 109 CFU of each vaccine strain twice at an interval of 4 weeks. Compared with a mock immunization, immunization with all three vaccine strains induced significant serum IgG responses against both Salmonella Typhimurium and Salmonella Newport LPS. The bacterial loads in the mouse tissues were significantly lower in the three vaccine-strain-immunized groups than in the mock group after either Salmonella Typhimurium or Salmonella

[Epidemiologic pattern of Salmonella enteritidis and Salmonella typhimurium in man--analysis of Salmonella cases in the Brandenburg federal territory].

PubMed

Käsbohrer, A; Talaska, T; Bögel, K; Stöhr, K; Lehmacher, W

1993-01-01

It is the aim of this study (a study that is part of several investigations suggested and coordinated by the WHO) to highlight the characteristics of transmission of Salmonella in humans. To achieve this, the data collected on the basis of the Federal German Law governing Epidemic Diseases as well as additionally available data (sex, serovar, differentiation between diseased and symptomatic, allocation to the respective place of residence) have been evaluated. In this manner it became possible to determine different patterns of incidence of the presently most frequently occurring salmonella serovars S. enteritidis and S. typhimurium in respect of distribution according to age and sex, as well as the dynamics of distribution and incidence in terms of time. The incidence is particularly remarkable among children, where S. enteritidis is not so frequent as S. typhimurium. There is a distinct trend towards the male sex among children in respect of the infestation. The fact that women are particularly often asymptomatic carriers points to the special nature of the sources and paths of infection. In respect of seasonal dynamics S. typhimurium does not have a specific summer peak, contrary to S. enteritidis, and this too indicates that the mechanisms of transmission or multiplication differ from one another. The study presented here is supplemented by the evaluation of further parameters to support and promote on-target epidemiological investigation into the various problems raised by this and other studies.

Modeling the survival of Salmonella Enteritidis and Salmonella Typhimurium during the fermentation of yogurt.

PubMed

Savran, Derya; Pérez-Rodríguez, Fernando; Halkman, A Kadir

2018-03-01

The objective of this study was to evaluate the behavior of Salmonella Enteritidis and Salmonella Typhimurium, the two most important serovars of salmonellosis , during the fermentation of yogurt. The microorganisms were enumerated in milk throughout the fermentation process at three initial inoculum levels (3, 5 and 7 log CFU/mL). DMFit software was used in the fitting procedure of the data (IFR, Norwich, UK, Version 3.5). The data provided sigmoidal curves that were successfully displayed with the Baranyi model. The results showed that the initial inoculum level did not affect the growth for both pathogens; thus, the µ max values (maximum specific growth rate) did not significantly differ across all the contamination levels, ranging from 0.26 to 0.38 for S. Enteritidis and from 0.50 to 0.56 log CFU/g/h for S. Typhimurium ( P > 0.05). However, the µ max values significantly differed between the two serovars ( P < 0.05). The λ values (lag time) did not have a clear trend in either of the pathogens. The present study showed that Salmonella can survive the fermentation process of milk even at a low contamination level. In addition, the models presented in this study can be used in quantitative risk assessment studies to estimate the threat to consumers.

[Outbreak of Salmonella Typhimurium infections associated with consumption of chorizo in Bizkaia].

PubMed

Hernández Arricibita, Esther; Santamaria Zuazua, Rosaura; Ramos López, Gemma; Herrera-León, Silvia; Kárkamo Zuñeda, José Antonio; Muniozguren Agirre, Nerea

2016-11-01

A report is presented on an outbreak of Salmonella enterica serovar Typhimurium infection that affected six people. The epidemiological and laboratory investigation associated the outbreak with the consumption of homemade chorizo purchased at a local street market. The vendor and producer were informed that the sale of meat products without sanitary authorization is prohibited, and the product was withdrawn from sale. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Low-Shear modeled microgravity alters the Salmonella enterica serovar typhimurium stress response in an RpoS-independent manner

NASA Technical Reports Server (NTRS)

Wilson, James W.; Ott, C. Mark; Ramamurthy, Rajee; Porwollik, Steffen; McClelland, Michael; Pierson, Duane L.; Nickerson, Cheryl A.

2002-01-01

We have previously demonstrated that low-shear modeled microgravity (low-shear MMG) serves to enhance the virulence of a bacterial pathogen, Salmonella enterica serovar Typhimurium. The Salmonella response to low-shear MMG involves a signaling pathway that we have termed the low-shear MMG stimulon, though the identities of the low-shear MMG stimulon genes and regulatory factors are not known. RpoS is the primary sigma factor required for the expression of genes that are induced upon exposure to different environmental-stress signals and is essential for virulence in mice. Since low-shear MMG induces a Salmonella acid stress response and enhances Salmonella virulence, we reasoned that RpoS would be a likely regulator of the Salmonella low-shear MMG response. Our results demonstrate that low-shear MMG provides cross-resistance to several environmental stresses in both wild-type and isogenic rpoS mutant strains. Growth under low-shear MMG decreased the generation time of both strains in minimal medium and increased the ability of both strains to survive in J774 macrophages. Using DNA microarray analysis, we found no evidence of induction of the RpoS regulon by low-shear MMG but did find that other genes were altered in expression under these conditions in both the wild-type and rpoS mutant strains. Our results indicate that, under the conditions of these studies, RpoS is not required for transmission of the signal that induces the low-shear MMG stimulon. Moreover, our studies also indicate that low-shear MMG can be added to a short list of growth conditions that can serve to preadapt an rpoS mutant for resistance to multiple environmental stresses.

Selectively Reduced Intracellular Proliferation of Salmonella enterica Serovar Typhimurium within APCs Limits Antigen Presentation and Development of a Rapid CD8 T Cell Response1

PubMed Central

Albaghdadi, Homam; Robinson, Nirmal; Finlay, Brett; Krishnan, Lakshmi; Sad, Subash

2014-01-01

Ag presentation to CD8+ T cells commences immediately after infection, which facilitates their rapid expansion and control of pathogen. This paradigm is not followed during infection with virulent Salmonella enterica serovar Typhimurium (ST), an intracellular bacterium that causes mortality in susceptible C57BL/6J mice within 7 days and a chronic infection in resistant mice (129 × 1SvJ). Infection of mice with OVA-expressing ST results in the development of a CD8+ T cell response that is detectable only after the second week of infection despite the early detectable bacterial burden. The mechanism behind the delayed CD8+ T cell activation was evaluated, and it was found that dendritic cells/macrophages or mice infected with ST-OVA failed to present Ag to OVA-specific CD8+ T cells. Lack of early Ag presentation was not rescued when mice or dendritic cells/macrophages were infected with an attenuated aroA mutant of ST or with mutants having defective Salmonella pathogenicity island I/II genes. Although extracellular ST proliferated extensively, the replication of ST was highly muted once inside macrophages. This muted intracellular proliferation of ST resulted in the generation of poor levels of intracellular Ag and peptide-MHC complex on the surface of dendritic cells. Additional experiments revealed that ST did not actively inhibit Ag presentation, rather it inhibited the uptake of another intracellular pathogen, Listeria monocytogenes, thereby causing inhibition of Ag presentation against L. monocytogenes. Taken together, this study reveals a dichotomy in the proliferation of ST and indicates that selectively reduced intra-cellular proliferation of virulent pathogens may be an important mechanism of immune evasion. PMID:19692639

Effects of Lactobacilli and lactose on Salmonella typhimurium colonisation and microbial fermentation in the crop of the young turkey.

PubMed

Cutler, S A; Rasmussen, M A; Hensley, M J; Wilhelms, K W; Griffith, R W; Scanes, C G

2005-12-01

1. Three experiments were performed to examine the effects of Lactobacilli and lactose on microbial fermentation and Salmonella enterica serovar Typhimurium colonisation in the crop of the young turkey. 2. The following carboxylic acids were detected in the crop ingesta: formic, acetic, butyric, lactic, valeric, caproic, oxalic, phenyl acetic, succinic and fumaric; propionic, isobutyric and isovaleric acids were not detectable. 3. At the beginning of the night, there were considerable quantities of ingesta in the crop of young turkeys. During the scotophase, there were progressive reductions in the contents and pH. Moreover, there were linear increases in the concentration of lactic, valeric and caproic acids (by approximately 7-fold over 8 h). Much smaller changes in crop pH were observed in the study where dietary treatments of Lactobacilli were not included. 4. Chronic addition of lactose or Lactobacilli to the diet exerted modest effects on the carboxylic acid concentration in the crop contents but did not consistently influence colonisation of the crop by Salmonella enterica serovar Typhimurium. 5. Young turkeys confine eating to the hours of illumination (photophase) with a peak in consumption prior to the subjective dusk.

Isolation of QseC-regulated genes in Salmonella enterica serovar Typhimurium by transposon mutgagenesis

USDA-ARS?s Scientific Manuscript database

Non-typhoidal Salmonella, a leading cause of U.S. foodborne disease and food-related deaths, often asymptomatically colonizes food-producing animals. In fact, >50% of U.S. swine production facilities test positive for Salmonella. The multidrug-resistant (MDR) Salmonella Typhimurium DT104 NCTC13348 c...

Influence of moisture content on inactivation of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in powdered red and black pepper spices by radio-frequency heating.

PubMed

Jeong, Seul-Gi; Kang, Dong-Hyun

2014-04-17

The influence of moisture content during radio-frequency (RF) heating on heating rate, dielectric properties, and inactivation of foodborne pathogens was investigated. The effect of RF heating on the quality of powdered red and black pepper spices with different moisture ranges was also investigated. Red pepper (12.6%, 15.2%, 19.1%, and 23.3% dry basis, db) and black pepper (10.1%, 17.2%, 23.7%, and 30.5% db) inoculated with Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium were treated in a RF heating system with 27.12 MHz. The heating rate of the sample was dependent on moisture content up to 19.1% (db) of red pepper and 17.2% (db) of black pepper, but there was a significant decrease in the heating rate when the moisture content was increased beyond these levels. The dielectric properties of both samples increased with a rise in moisture content. As the moisture content increased, treatment time required to reduce E. coli O157:H7 and S. Typhimurium by more than 7 log CFU/g (below the detection limit, 1 log CFU/g) decreased and then increased again without affecting product quality when the moisture content exceeded a level corresponding to the peak heating rate. RF treatment significantly (P<0.05) reduced moisture content of both spices. These results suggest that RF heating can be effectively used to not only control pathogens but also reduce moisture levels in spices and that the effect of inactivation is dependent on moisture content. Copyright © 2014 Elsevier B.V. All rights reserved.

Efficient visible light induced synthesis of silver nanoparticles by Penicillium polonicum ARA 10 isolated from Chetomorpha antennina and its antibacterial efficacy against Salmonella enterica serovar Typhimurium.

PubMed

Neethu, Sahadevan; Midhun, Sebastian Jose; Sunil, M A; Soumya, Soman; Radhakrishnan, E K; Jyothis, Mathew

2018-03-01

The green synthesis of silver nanoparticles (AgNPs) using biological systems such as fungi has evolved to become an important area of nanobiotechnology. Herein, we report for the first time the light-induced extracellular synthesis of silver nanoparticles using algicolous endophytic fungus Penicillium polonicum ARA 10, isolated from the marine green alga Chetomorpha antennina. Parametric optimization, including the concentration of AgNO 3 , fungal biomass, ratio of cell filtrate and AgNO 3 , pH, reaction time and presence of light, was done for rapid AgNPs production. The obtained silver nanoparticles (AgNPs) were characterized by UV-Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and Transmission electron microscopy (HRTEM-EDAX). The AgNPs showed a characteristic UV-visible peak at 430 nm with an average size of 10-15 nm. The NH stretches in FTIR indicate the presence of protein molecules. The Raman vibrational bands suggest that the molecules responsible for the reduction and stability of AgNPs were extracellular proteins produced by P.polonicum. Antibacterial evaluation of AgNPs against the major foodborne bacterial pathogen Salmonella enterica serovar Typhimurium MTCC 1251, was assessed by well diffusion, Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assay. Killing kinetic studies revealed complete killing of the bacterial cells within 4 h and the bactericidal nature of synthesized nanoparticles was confirmed by fluorescent microscopy and scanning electron microscopy. Furthermore, the bactericidal studies with Transmission electron microscopy (TEM) at different time intervals explored the presence of AgNPs in the cell wall of S.Typhimurium at about 30 min and the complete bacterial lysis was found at 24 h. The current research opens an insight into the green synthesis of AgNPs and the mechanism of bacterial lysis by direct damage to the cell wall. Copyright © 2018 Elsevier

Molecular typing of Salmonella enterica serovar typhi isolates from various countries in Asia by a multiplex PCR assay on variable-number tandem repeats.

PubMed

Liu, Yichun; Lee, May-Ann; Ooi, Eng-Eong; Mavis, Yeo; Tan, Ai-Ling; Quek, Hung-Hiang

2003-09-01

A multiplex PCR method incorporating primers flanking three variable-number tandem repeat (VNTR) loci (arbitrarily labeled TR1, TR2, and TR3) in the CT18 strain of Salmonella enterica serovar Typhi has been developed for molecular typing of S. enterica serovar Typhi clinical isolates from several Asian countries, including Singapore, Indonesia, India, Bangladesh, Malaysia, and Nepal. We have demonstrated that the multiplex PCR could be performed on crude cell lysates and that the VNTR banding profiles produced could be easily analyzed by visual inspection after conventional agarose gel electrophoresis. The assay was highly discriminative in identifying 49 distinct VNTR profiles among 59 individual isolates. A high level of VNTR profile heterogeneity was observed in isolates from within the same country and among countries. These VNTR profiles remained stable after the strains were passaged extensively under routine laboratory culture conditions. In contrast to the S. enterica serovar Typhi isolates, an absence of TR3 amplicons and a lack of length polymorphisms in TR1 and TR2 amplicons were observed for other S. enterica serovars, such as Salmonella enterica serovar Typhimurium, Salmonella enterica serovar Enteritidis, and Salmonella enterica serovar Paratyphi A, B, and C. DNA sequencing of the amplified VNTR regions substantiated these results, suggesting the high stability of the multiplex PCR assay. The multiplex-PCR-based VNTR profiling developed in this study provides a simple, rapid, reproducible, and high-resolution molecular tool for the epidemiological analysis of S. enterica serovar Typhi strains.

Poly D,L-lactide-co-glycolide (PLGA) nanoparticle-encapsulated honeybee (Apis melifera) venom promotes clearance of Salmonella enterica serovar Typhimurium infection in experimentally challenged pigs through the up-regulation of T helper type 1 specific immune responses.

PubMed

Lee, Jin-A; Jung, Bock-Gie; Kim, Tae-Hoon; Kim, Yun-Mi; Park, Min-Ho; Hyun, Pung-mi; Jeon, Jong-woon; Park, Jin-kyu; Cho, Cheong-Weon; Suh, Guk-Hyun; Lee, Bong-Joo

2014-10-15

Honeybee (Apis melifera) venom (HBV), which includes melittin and lipid-soluble ingredients (chrysin and pinocembrin), elicited increases in the CD4(+)/CD8(+) T lymphocyte ratio, relative mRNA expression levels of the T helper type 1 (Th 1) cytokines (interferon-γ and IL-12) and reinforced viral clearance of an experimental porcine reproductive and respiratory syndrome (PRRS) virus infection in our previous study. On the basis of that previous study, we have now developed poly-d,l-lactide-co-glycolide (PLGA)-encapsulated HBV nanoparticles (P-HBV) for longer sustained release of HBV. We administered P-HBV to pigs via the rectal route, and then evaluated the potential immune-enhancing and bacterial clearance effects of P-HBV against Salmonella enterica serovar Typhimurium. The CD4(+)/CD8(+) lymphocyte ratio, proliferative capacity of peripheral blood lymphocytes and relative mRNA expression levels of IFN-γ and IL-12 (produced mainly by Th1 lymphocytes) were significantly increased in the P-HBV group up to 2 weeks post-administration of P-HBV. After S. Typhimurium infection, the P-HBV group showed a marked reduction in microbial burden in feces and all tissue samples (including the ileum, cecum, colon, and mesenteric lymph node (MLN)), a significant increase in Th 1 cytokines (IFN-γ, IL-2, and IL-12) and a marked decrease in a Th 2 cytokine (IL-4) in all tissue samples and peripheral blood lymphocytes. Thus, P-HBV may be a promising strategy for immune enhancement and prevention of S. Typhimurium or other bacterial infections. Copyright © 2014 Elsevier B.V. All rights reserved.

Pediatric Epidemic of Salmonella enterica Serovar Typhimurium in the Area of L'Aquila, Italy, Four Years after a Catastrophic Earthquake.

PubMed

Nigro, Giovanni; Bottone, Gabriella; Maiorani, Daniela; Trombatore, Fabiana; Falasca, Silvana; Bruno, Gianfranco

2016-05-06

A Salmonella enterica epidemic occurred in children of the area of L'Aquila (Central Italy, Abruzzo region) between June 2013 and October 2014, four years after the catastrophic earthquake of 6 April 2009. Clinical and laboratory data were collected from hospitalized and ambulatory children. Routine investigations for Salmonella infection were carried out on numerous alimentary matrices of animal origin and sampling sources for drinking water of the L'Aquila district, including pickup points of the two main aqueducts. Salmonella infection occurred in 155 children (83 females: 53%), aged 1 to 15 years (mean 2.10). Of these, 44 children (28.4%) were hospitalized because of severe dehydration, electrolyte abnormalities, and fever resistant to oral antipyretic and antibiotic drugs. Three children (1.9%) were reinfected within four months after primary infection by the same Salmonella strain. Four children (2.6%), aged one to two years, were coinfected by rotavirus. A seven-year old child had a concomitant right hip joint arthritis. The isolated strains, as confirmed in about the half of cases or probable/possible in the remaining ones, were identified as S. enterica serovar Typhimurium [4,5:i:-], monophasic variant. Aterno river, bordering the L'Aquila district, was recognized as the main responsible source for the contamination of local crops and vegetables derived from polluted crops. The high rate of hospitalized children underlines the emergence of a highly pathogenic S. enterica strain probably subsequent to the contamination of the spring water sources after geological changes occurred during the catastrophic earthquake.

Differential antibacterial response of chicken granulosa cells to invasion by Salmonella serovars.

PubMed

Babu, Uma S; Harrison, Lisa M; Patel, Isha R; Ramirez, Gerardo A; Williams, Kristina M; Pereira, Marion; Balan, Kannan V

2016-06-01

In the United States, Salmonella enterica ser. Enteritidis (SE) is among the leading bacterial cause of foodborne illness via consumption of raw or undercooked eggs. The top Salmonella serovars implicated in U.S. foodborne outbreaks associated with chicken consumption include SE, Typhimurium (ST), Heidelberg (SH), Montevideo, Mbandka, Braenderup, and Newport. While enforcement actions target the eradication of SE from layer hens, there is a growing concern that other serovars could occupy this niche and be a cause of egg-transmitted human salmonellosis. Therefore, we tested the invasion and survival of SE, SH, ST, and Salmonella enterica ser. Hadar (S. Hadar) at 4 and 20 h post infection (hpi) in chicken ovarian granulosa cells (cGC); a cellular layer which surrounds the previtelline layer and central yolk in egg-forming follicles. We also evaluated cGC transcriptional changes, using an antibacterial response PCR array, to assess host response to intracellular SalmonellaWe observed that invasion of cGC by SE, SH, and ST was significantly higher than invasion by S. Hadar, with ST showing the highest level of invasion. The Bacterial Survival Index, defined as the ratio of intracellular bacteria at 20 and 4 h, were 18.94, 7.35, and 15.27 for SE, SH, and ST, respectively, with no significant difference in survival between SE or ST compared to SH. Evaluation of cGC anti-Salmonella gene responses indicated that at 4 hpi there was a significant decrease in Toll-like receptor (TLR)-4 mRNA in cGC infected with SE, whereas TLR5 and myeloid differentiation primary response gene 88 were significantly down regulated across all serovars. At 4 hpi, invasion by Salmonella serovars resulted in significant upregulation of several antimicrobial genes, and proinflammatory cytokines and chemokines (PICs). At 20 hpi, all the serovars induced PICs with SH being the strongest inducer. Additionally, SE, SH and ST differentially induced signal transduction pathways. Although only a single

Resolving the contributions of the membrane-bound and periplasmic nitrate reductase systems to nitric oxide and nitrous oxide production in Salmonella enterica serovar Typhimurium.

PubMed

Rowley, Gary; Hensen, Daniela; Felgate, Heather; Arkenberg, Anke; Appia-Ayme, Corinne; Prior, Karen; Harrington, Carl; Field, Sarah J; Butt, Julea N; Baggs, Elizabeth; Richardson, David J

2012-01-15

The production of cytotoxic nitric oxide (NO) and conversion into the neuropharmacological agent and potent greenhouse gas nitrous oxide (N₂O) is linked with anoxic nitrate catabolism by Salmonella enterica serovar Typhimurium. Salmonella can synthesize two types of nitrate reductase: a membrane-bound form (Nar) and a periplasmic form (Nap). Nitrate catabolism was studied under nitrate-rich and nitrate-limited conditions in chemostat cultures following transition from oxic to anoxic conditions. Intracellular NO production was reported qualitatively by assessing transcription of the NO-regulated genes encoding flavohaemoglobin (Hmp), flavorubredoxin (NorV) and hybrid cluster protein (Hcp). A more quantitative analysis of the extent of NO formation was gained by measuring production of N₂O, the end-product of anoxic NO-detoxification. Under nitrate-rich conditions, the nar, nap, hmp, norV and hcp genes were all induced following transition from the oxic to anoxic state, and 20% of nitrate consumed in steady-state was released as N₂O when nitrite had accumulated to millimolar levels. The kinetics of nitrate consumption, nitrite accumulation and N₂O production were similar to those of wild-type in nitrate-sufficient cultures of a nap mutant. In contrast, in a narG mutant, the steady-state rate of N₂O production was ~30-fold lower than that of the wild-type. Under nitrate-limited conditions, nap, but not nar, was up-regulated following transition from oxic to anoxic metabolism and very little N₂O production was observed. Thus a combination of nitrate-sufficiency, nitrite accumulation and an active Nar-type nitrate reductase leads to NO and thence N₂O production, and this can account for up to 20% of the nitrate catabolized.

SEROVARS AND ANTIMICROBIAL RESISTANCE OF Salmonella spp. ISOLATED FROM TURKEY AND BROILER CARCASSES IN SOUTHERN BRAZIL BETWEEN 2004 AND 2006

PubMed Central

PALMEIRA, Andre; dos SANTOS, Luciana Ruschel; BORSOI, Anderlise; RODRIGUES, Laura Beatriz; CALASANS, Max; do NASCIMENTO, Vladimir Pinheiro

2016-01-01

Salmonella spp. causes diseases in fowls, when species-specific serovars (Salmonella Pullorum and S.Gallinarum) are present in flocks, and public health problems, when non-typhoid serovars are isolated, as well as possible bacterial resistance induced by the preventive and therapeutic use of antimicrobials in animal production. This study describes the serovars and bacterial resistance of 280Salmonella spp. strains isolated from turkey and broiler carcasses in Southern Brazil between 2004 and 2006. SalmonellaEnteritidis was the most prevalent serovar (55.7%), followed by Heidelberg (5.0%), Agona (4.3%), Bredeney (3.9%), Hadar (3.2%), and Typhimurium (2.9%). Tennessee and S. Enterica subspecies enterica(O: 4.5) were isolated only in turkeys, and Hadar (18.6%) was the most prevalent serovar in this species. Antimicrobial susceptibility tests were performed in 178 isolates (43 from turkeys and 135 from broilers). All isolates were sensitive to amoxicillin + clavulanic acid, polymyxin B, ciprofloxacin, and norfloxacin, and were resistant to bacitracin and penicillin. Broiler carcass isolates showed resistance to nalidixic acid (48.9%), nitrofurantoin (34.3%), neomycin (9.6%), tetracycline (5.2%), and kanamycin (8.9%); and turkey carcass isolates were resistant to nalidixic acid (62.8%), tetracycline (34.9%), and neomycin (30.2%), with a significant difference in turkeys when compared to broiler carcass isolates. These results indicate the need for judicious use of antimicrobials in livestock production, given that the serovars identified are potential causes of food poisoning. PMID:27007562

Persistence and clearance of different Salmonella serovars in buildings housing laying hens.

PubMed

Carrique-Mas, J J; Breslin, M; Snow, L; McLaren, I; Sayers, A R; Davies, R H

2009-06-01

We investigated factors associated with persistence of different Salmonella serovars in buildings housing laying hens in Great Britain using survival analysis. A total of 264 incidents of Salmonella detection occurring between July 1998 and August 2007 in 152 houses were recorded. For incidents involving Salmonella Enteritidis (SE), both the rodent score of the house and the type of house were positively associated with persistence. For non-SE serovars, only the type of house was associated with persistence. Persistence of SE in the houses was longest (>15 months) in step-cage and cage-scraper houses when high levels of rodents were present, and lowest in non-cage and cage-belt houses. We estimated that 42% (95% CI 23.3-63.1) of SE incidents may be cleared during the lay period, and this was related to elimination of rodents from the houses. From January 2009, EU legislation will ban the sale of fresh eggs from SE-positive and S. Typhimurium-positive flocks over their remaining lifespan. If infection is eliminated from such flocks, they would cease to represent a public health risk.

β-Galactomannan and Saccharomyces cerevisiae var. boulardii modulate the immune response against Salmonella enterica serovar Typhimurium in porcine intestinal epithelial and dendritic cells.

PubMed

Badia, Roger; Brufau, M Teresa; Guerrero-Zamora, Ana Maria; Lizardo, Rosil; Dobrescu, Irina; Martin-Venegas, Raquel; Ferrer, Ruth; Salmon, Henri; Martínez, Paz; Brufau, Joaquim

2012-03-01

Salmonella enterica serovar Typhimurium is a facultative intracellular pathogen that causes inflammation, necrosis, and diarrhea in pigs, as well as being an important source of food-borne diseases in humans. Probiotics and prebiotics are promising alternatives to antibiotics to control and prevent intestinal infections. The present work investigated a recently developed β-galactomannan (βGM) prebiotic compared to the proven probiotic Saccharomyces cerevisiae var. boulardii on porcine ileum intestinal epithelial cells (IECs) of the IPI-2I line and monocyte-derived dendritic cells (DCs) cocultured in vitro with Salmonella. We observed that both S. cerevisiae var. boulardii and βGM inhibited the association of Salmonella with IECs in vitro. Our data indicated that βGM has a higher ability than S. cerevisiae var. boulardii to inhibit Salmonella-induced proinflammatory mRNA (cytokines tumor necrosis factor alpha [TNF-α], interleukin-1α [IL-1α], IL-6, and granulocyte-macrophage colony-stimulating factor [GM-CSF] and chemokines CCL2, CCL20, and CXCL8) and at protein levels (IL-6 and CXCL8). Additionally, βGM and S. cerevisiae var. boulardii induced some effects on DCs that were not observed on IECs: βGM and S. cerevisiae var. boulardii showed slight upregulation of mRNA for TNF-α, GM-CSF, and CCR7 receptor on porcine monocyte-derived dendritic cells (DCs). Indeed, the addition of βGM or S. cerevisiae var. boulardii on DCs cocultured with Salmonella showed higher gene expression (mRNA) for TNF-α, GM-CSF, and CXCL8 compared to that of the control with Salmonella. In conclusion, the addition of βGM inhibits Salmonella-induced proinflammatory profiles in IECs but may promote DC activation, although associated molecular mechanisms remain to be elucidated.

β-Galactomannan and Saccharomyces cerevisiae var. boulardii Modulate the Immune Response against Salmonella enterica Serovar Typhimurium in Porcine Intestinal Epithelial and Dendritic Cells

PubMed Central

Brufau, M. Teresa; Guerrero-Zamora, Ana Maria; Lizardo, Rosil; Dobrescu, Irina; Martin-Venegas, Raquel; Ferrer, Ruth; Salmon, Henri; Martínez, Paz

2012-01-01

Salmonella enterica serovar Typhimurium is a facultative intracellular pathogen that causes inflammation, necrosis, and diarrhea in pigs, as well as being an important source of food-borne diseases in humans. Probiotics and prebiotics are promising alternatives to antibiotics to control and prevent intestinal infections. The present work investigated a recently developed β-galactomannan (βGM) prebiotic compared to the proven probiotic Saccharomyces cerevisiae var. boulardii on porcine ileum intestinal epithelial cells (IECs) of the IPI-2I line and monocyte-derived dendritic cells (DCs) cocultured in vitro with Salmonella. We observed that both S. cerevisiae var. boulardii and βGM inhibited the association of Salmonella with IECs in vitro. Our data indicated that βGM has a higher ability than S. cerevisiae var. boulardii to inhibit Salmonella-induced proinflammatory mRNA (cytokines tumor necrosis factor alpha [TNF-α], interleukin-1α [IL-1α], IL-6, and granulocyte-macrophage colony-stimulating factor [GM-CSF] and chemokines CCL2, CCL20, and CXCL8) and at protein levels (IL-6 and CXCL8). Additionally, βGM and S. cerevisiae var. boulardii induced some effects on DCs that were not observed on IECs: βGM and S. cerevisiae var. boulardii showed slight upregulation of mRNA for TNF-α, GM-CSF, and CCR7 receptor on porcine monocyte-derived dendritic cells (DCs). Indeed, the addition of βGM or S. cerevisiae var. boulardii on DCs cocultured with Salmonella showed higher gene expression (mRNA) for TNF-α, GM-CSF, and CXCL8 compared to that of the control with Salmonella. In conclusion, the addition of βGM inhibits Salmonella-induced proinflammatory profiles in IECs but may promote DC activation, although associated molecular mechanisms remain to be elucidated. PMID:22301691

Evolutionary genetic relationships of clones of Salmonella serovars that cause human typhoid and other enteric fevers.

PubMed Central

Selander, R K; Beltran, P; Smith, N H; Helmuth, R; Rubin, F A; Kopecko, D J; Ferris, K; Tall, B D; Cravioto, A; Musser, J M

1990-01-01

Multilocus enzyme electrophoresis was employed to measure chromosomal genotypic diversity and evolutionary relationships among 761 isolates of the serovars Salmonella typhi, S. paratyphi A, S. paratyphi B, S. paratyphi C, and S. sendai, which are human-adapted agents of enteric fever, and S. miami and S. java, which are serotypically similar to S. sendai and S. paratyphi B, respectively, but cause gastroenteritis in both humans and animals. To determine the phylogenetic positions of the clones of these forms within the context of the salmonellae of subspecies I, comparative data for 22 other common serovars were utilized. Except for S. paratyphi A and S. sendai, the analysis revealed no close phylogenetic relationships among clones of different human-adapted serovars, which implies convergence in host adaptation and virulence factors. Clones of S. miami are not allied with those of S. sendai or S. paratyphi A, being, instead, closely related to strains of S. panama. Clones of S. paratyphi B and S. java belong to a large phylogenetic complex that includes clones of S. typhimurium, S. heidelberg, S. saintpaul, and S. muenchen. Most strains of S. paratyphi B belong to a globally distributed clone that is highly polymorphic in biotype, bacteriophage type, and several other characters, whereas strains of S. java represent seven diverse lineages. The flagellar monophasic forms of S. java are genotypically more similar to clones of S. typhimurium than to other clones of S. java or S. paratyphi B. Clones of S. paratyphi C are related to those of S. choleraesuis. DNA probing with a segment of the viaB region specific for the Vi capsular antigen genes indicated that the frequent failure of isolates of S. paratyphi C to express Vi antigen is almost entirely attributable to regulatory processes rather than to an absence of the structural determinant genes themselves. Two clones of S. typhisuis are related to those of S. choleraesuis and S. paratyphi C, but a third clone is not

Salmonella enterica serovar typhimurium colonization of the crop in the domestic turkey: influence of probiotic and prebiotic treatment (Lactobacillus acidophilus and lactose).

PubMed

Johannsen, Sara A; Griffith, Ronald W; Wesley, Irene V; Scanes, Colin G

2004-01-01

Acute colonization of the crop of the domestic turkey by Salmonella enterica serovar typhimurium (ST) was examined. The influences of preharvest probiotic and prebiotic treatment with lactobaccilli and lactose on crop colonization with ST were also investigated. Prior to Salmonella challenge, poults received 2.5% lactose and Lactobacillus acidophilus (1.9 x 10(9) organisms/liter) in the only source of drinking water from 1 day old to termination. At 3-wk-old, turkey poults were challenged with ST (1.7 X 10(8) colony-forming units [CFU]/ml) before their natural nocturnal fast to determine the potential effects of supplementation on crop colonization when the crop was engorged and subsequently undergoing emptying. Crop ingesta and tissue were collected at time points 30 min and 4, 8, and 24 hr postchallenge and ST levels were determined. High levels of ST were detected in the crop. For instance, for the poults not receiving lactose or lactobacilli, 30 min after ST challenge, there were 4.4 x 10(7) CFU in the crop ingesta and 5.3 x 10(5) CFU in the crop wall. Ingesta ST levels dropped dramatically to 1.0 x 10(6) CFU after 4 hr as the crop emptied. Crop wall ST levels were steady during the nocturnal crop evacuation. Immunohistochemical staining demonstrated ST in close association with the crop epithelium. Treatment with lactose and L. acidophilus supplementation did not reduce ST colonization.

Horizontal gene transfer of a ColV plasmid has resulted in a dominant avian clonal type of Salmonella enterica serovar Kentucky.

PubMed

Johnson, Timothy J; Thorsness, Jessica L; Anderson, Cole P; Lynne, Aaron M; Foley, Steven L; Han, Jing; Fricke, W Florian; McDermott, Patrick F; White, David G; Khatri, Mahesh; Stell, Adam L; Flores, Cristian; Singer, Randall S

2010-12-22

Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from broiler chickens. Recent work suggests that its emergence apparently coincides with its acquisition of a ColV virulence plasmid. In the present study, we examined 902 Salmonella isolates belonging to 59 different serovars for the presence of this plasmid. Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%). We demonstrated that a single PFGE clonal type of S. Kentucky harbors this plasmid, and acquisition of this plasmid by S. Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease. Comparison of the completed sequences of three ColV plasmids from S. Kentucky isolated from different geographical locales, timepoints and sources revealed a nearly identical genetic structure with few single nucleotide changes or insertions/deletions. Overall, it appears that the ColV plasmid was recently acquired by a single clonal type S. Kentucky and confers to its host enhanced colonization and fitness capabilities. Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard.

Horizontal Gene Transfer of a ColV Plasmid Has Resulted in a Dominant Avian Clonal Type of Salmonella enterica Serovar Kentucky

PubMed Central

Johnson, Timothy J.; Thorsness, Jessica L.; Anderson, Cole P.; Lynne, Aaron M.; Foley, Steven L.; Han, Jing; Fricke, W. Florian; McDermott, Patrick F.; White, David G.; Khatri, Mahesh; Stell, Adam L.; Flores, Cristian; Singer, Randall S.

2010-01-01

Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from broiler chickens. Recent work suggests that its emergence apparently coincides with its acquisition of a ColV virulence plasmid. In the present study, we examined 902 Salmonella isolates belonging to 59 different serovars for the presence of this plasmid. Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%). We demonstrated that a single PFGE clonal type of S. Kentucky harbors this plasmid, and acquisition of this plasmid by S. Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease. Comparison of the completed sequences of three ColV plasmids from S. Kentucky isolated from different geographical locales, timepoints and sources revealed a nearly identical genetic structure with few single nucleotide changes or insertions/deletions. Overall, it appears that the ColV plasmid was recently acquired by a single clonal type S. Kentucky and confers to its host enhanced colonization and fitness capabilities. Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard. PMID:21203520

Aggregation via the Red, Dry, and Rough Morphotype Is Not a Virulence Adaptation in Salmonella enterica Serovar Typhimurium▿

PubMed Central

White, A. P.; Gibson, D. L.; Grassl, G. A.; Kay, W. W.; Finlay, B. B.; Vallance, B. A.; Surette, M. G.

2008-01-01

The Salmonella rdar (red, dry, and rough) morphotype is an aggregative and resistant physiology that has been linked to survival in nutrient-limited environments. Growth of Salmonella enterica serovar Typhimurium was analyzed in a variety of nutrient-limiting conditions to determine whether aggregation would occur at low cell densities and whether the rdar morphotype was involved in this process. The resulting cultures consisted of two populations of cells, aggregated and nonaggregated, with the aggregated cells preferentially displaying rdar morphotype gene expression. The two groups of cells could be separated based on the principle that aggregated cells were producing greater amounts of thin aggregative fimbriae (Tafi or curli). In addition, the aggregated cells retained some physiological characteristics of the rdar morphotype, such as increased resistance to sodium hypochlorite. Competitive infection experiments in mice showed that nonaggregative ΔagfA cells outcompeted rdar-positive wild-type cells in all tissues analyzed, indicating that aggregation via the rdar morphotype was not a virulence adaptation in Salmonella enterica serovar Typhimurium. Furthermore, in vivo imaging experiments showed that Tafi genes were not expressed during infection but were expressed once Salmonella was passed out of the mice into the feces. We hypothesize that the primary role of the rdar morphotype is to enhance Salmonella survival outside the host, thereby aiding in transmission. PMID:18195033

O-Serotype Conversion in Salmonella Typhimurium Induces Protective Immune Responses against Invasive Non-Typhoidal Salmonella Infections.

PubMed

Li, Pei; Liu, Qing; Luo, Hongyan; Liang, Kang; Yi, Jie; Luo, Ying; Hu, Yunlong; Han, Yue; Kong, Qingke

2017-01-01

Salmonella infections remain a big problem worldwide, causing enteric fever by Salmonella Typhi (or Paratyphi) or self-limiting gastroenteritis by non-typhoidal Salmonella (NTS) in healthy individuals. NTS may become invasive and cause septicemia in elderly or immuno-compromised individuals, leading to high mortality and morbidity. No vaccines are currently available for preventing NTS infection in human. As these invasive NTS are restricted to several O-antigen serogroups including B1, D1, C1, and C2, O-antigen polysaccharide is believed to be a good target for vaccine development. In this study, a strategy of O-serotype conversion was investigated to develop live attenuated S . Typhimurium vaccines against the major serovars of NTS infections. The immunodominant O4 serotype of S . Typhimurium was converted into O9, O7, and O8 serotypes through unmarked chromosomal deletion-insertion mutations. O-serotype conversion was confirmed by LPS silver staining and western blotting. All O-serotype conversion mutations were successfully introduced into the live attenuated S . Typhimurium vaccine S738 (Δ crp Δ cya ) to evaluate their immunogenicity in mice model. The vaccine candidates induced high amounts of heterologous O-polysaccharide-specific functional IgG responses. Vaccinated mice survived a challenge of 100 times the 50% lethality dose (LD 50 ) of wild-type S . Typhimurium. Protective efficacy against heterologous virulent Salmonella challenges was highly O-serotype related. Furthermore, broad-spectrum protection against S . Typhimurium, S . Enteritidis, and S . Choleraesuis was observed by co-vaccination of O9 and O7 O-serotype-converted vaccine candidates. This study highlights the strategy of expressing heterologous O-polysaccharides via genetic engineering in developing live attenuated S . Typhimurium vaccines against NTS infections.

Effect of Frequency and Waveform on Inactivation of Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium in Salsa by Ohmic Heating

PubMed Central

Lee, Su-Yeon; Ryu, Sangryeol

2013-01-01

The effect of frequency of alternating current during ohmic heating on electrode corrosion, heating rate, inactivation of food-borne pathogens, and quality of salsa was investigated. The impact of waveform on heating rate was also investigated. Salsa was treated with various frequencies (60 Hz to 20 kHz) and waveforms (sine, square, and sawtooth) at a constant electric field strength of 12.5 V/cm. Electrode corrosion did not occur when the frequency exceeded 1 kHz. The heating rate of the sample was dependent on frequency up to 500 Hz, but there was no significant difference (P > 0.05) in the heating rate when the frequency was increased above 1 kHz. The electrical conductivity of the sample increased with a rise in the frequency. At a frequency of 60 Hz, the square wave produced a lower heating rate than that of sine and sawtooth waves. The heating rate between waveforms was not significantly (P > 0.05) different when the frequency was >500 Hz. As the frequency increased, the treatment time required to reduce Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium to below the detection limit (1 log CFU/g) decreased without affecting product quality. These results suggest that ohmic heating can be effectively used to pasteurize salsa and that the effect of inactivation is dependent on frequency and electrical conductivity rather than waveform. PMID:23023752

Effect of frequency and waveform on inactivation of Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium in salsa by ohmic heating.

PubMed

Lee, Su-Yeon; Ryu, Sangryeol; Kang, Dong-Hyun

2013-01-01

The effect of frequency of alternating current during ohmic heating on electrode corrosion, heating rate, inactivation of food-borne pathogens, and quality of salsa was investigated. The impact of waveform on heating rate was also investigated. Salsa was treated with various frequencies (60 Hz to 20 kHz) and waveforms (sine, square, and sawtooth) at a constant electric field strength of 12.5 V/cm. Electrode corrosion did not occur when the frequency exceeded 1 kHz. The heating rate of the sample was dependent on frequency up to 500 Hz, but there was no significant difference (P > 0.05) in the heating rate when the frequency was increased above 1 kHz. The electrical conductivity of the sample increased with a rise in the frequency. At a frequency of 60 Hz, the square wave produced a lower heating rate than that of sine and sawtooth waves. The heating rate between waveforms was not significantly (P > 0.05) different when the frequency was >500 Hz. As the frequency increased, the treatment time required to reduce Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium to below the detection limit (1 log CFU/g) decreased without affecting product quality. These results suggest that ohmic heating can be effectively used to pasteurize salsa and that the effect of inactivation is dependent on frequency and electrical conductivity rather than waveform.

Internalisation potential of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium and Staphylococcus aureus in lettuce seedlings and mature plants.

PubMed

Standing, Taryn-Ann; du Plessis, Erika; Duvenage, Stacey; Korsten, Lise

2013-06-01

The internalisation potential of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium in lettuce was evaluated using seedlings grown in vermiculite in seedling trays as well as hydroponically grown lettuce. Sterile distilled water was spiked with one of the four human pathogenic bacteria (10(5) CFU/mL) and used to irrigate the plants. The potential for pathogen internalisation was investigated over time using light microscopy, transmission electron microscopy and viable plate counts. Additionally, the identities of the pathogens isolated from internal lettuce plant tissues were confirmed using polymerase chain reaction with pathogen-specific oligonucleotides. Internalisation of each of the human pathogens was evident in both lettuce seedlings and hydroponically grown mature lettuce plants. To our knowledge, this is the first report of S. aureus internalisation in lettuce plants. In addition, the levels of background microflora in the lettuce plants were determined by plate counting and the isolates identified using matrix-assisted laser ionisation-time of flight (MALDI-TOF). Background microflora assessments confirmed the absence of the four pathogens evaluated in this study. A low titre of previously described endophytes and soil inhabitants, i.e., Enterobacter cloacae, Enterococcus faecalis, Lysinibacillus fusiformis, Rhodococcus rhodochrous, Staphylococcus epidermidis and Staphylococcus hominis were identified.

Salmonella Typhimurium metabolism affects virulence in the host - A mini-review.

PubMed

Herrero-Fresno, Ana; Olsen, John Elmerdhahl

2018-05-01

Salmonella enterica remains an important food borne pathogen in all regions of the world with S. Typhimurium as one of the most frequent serovars causing food borne disease. Since the majority of human cases are caused by food of animal origin, there has been a high interest in understanding how S. Typhimurium interacts with the animal host, mostly focusing on factors that allow it to breach host barriers and to manipulate host cells to the benefit of itself. Up to recently, such studies have ignored the metabolic factors that allow the bacteria to multiply in the host, but this is changing rapidly, and we are now beginning to understand that virulence and metabolism in the host are closely linked. The current review highlights which metabolic factors that are essential for Salmonella Typhimurium growth in the intestine, in cultured epithelial and macrophage-like cell lines, at systemic sites during invasive salmonellosis, and during long term asymptomatic colonization of the host. It also points to the limitations in our current knowledge, most notably that most studies have been carried out with few well-characterized laboratory strains, that we do not know how much the in vivo metabolism differs between serotypes, and that most results are based on challenges in the mouse model of infection. It will be very important to realize whether the current understanding of Salmonella metabolism in the host is true for all serotypes and all possible hosts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification of multidrug-resistant Salmonella enterica serovar typhimurium isolates that have an antibiotic-induced invasion phenotype

USDA-ARS?s Scientific Manuscript database

Multidrug-resistant (MDR) Salmonella is an important food safety issue in humans and animals. The National Antimicrobial Resistance Monitoring System (NARMS) has reported that 27.3% of Salmonella enterica serotype Typhimurium isolates in humans were resistant to three or more classes of antibiotics...

Live, attenuated Salmonella typhimurium vectoring Campylobacter antigens.

PubMed

Sizemore, Donata R; Warner, Beth; Lawrence, Julie; Jones, Amy; Killeen, Kevin P

2006-05-01

We describe the evaluation of three live, attenuated deltaphoP/Q Salmonella enteric serovar Typhimurium strains expressing PEB1 minus its signal sequence (PEB1-ss) from three different plasmids: a pBR-based asd plasmid, an arabinose-based runaway plasmid, which each expressed PEB1-ss in the bacterial cytosol, and a PEB1::HlyA fusion plasmid that directs secretion of PEB1-ss into the extracellular milieu. Serum IgG responses specific for PEB1-ss were induced by pBR-derived and runaway plasmids, with 100 and 90% seroconversion, respectively, at a 1:500 dilution of anti-sera as measured by Western blot analysis, while the PEB1-ss::HlyA fusion plasmid induced serum IgG in only 20% of the mice. Although significant levels of anti-PEB serum IgG were induced, no protection against oral Campylobacter jejuni challenge was observed.

Effects of bacterial dose and fly sex on persistence and excretion of Salmonella enterica serovar Typhimurium from adult house flies (Diptera: Muscidae)

USDA-ARS?s Scientific Manuscript database

Salmonella Typhimurium is a pathogen that causes gastroenteritis in humans and can be harbored by house flies. Factors influencing excretion of S. Typhimurium from infected flies have not been elucidated, but are essential for assessing transmission potential. We determined the persistence and excre...

Clinical and veterinary isolates of Salmonella enterica serovar Enteritidis defective in lipopolysaccharide O-chain polymerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guard-Petter, J.; Parker, C.T.; Asokan, K.

1999-05-01

Twelve human and chicken isolates of Salmonella enterica serovar Enteritidis belonging to phage types 4, 8, 13a, and 23 were characterized for variability in lipopolysaccharide (LPS) composition. Isolates were differentiated into two groups, i.e., those that lacked immunoreactive O-chain, termed rough isolates, and those that had immunoreactive O-chain, termed smooth isolates. Isolates within these groups could be further differentiated by LPS compositional differences as detected by gel electrophoresis and gas liquid chromatography of samples extracted with water, which yielded significantly more LPS in comparison to phenol-chloroform extraction. The rough isolates were of two types, the O-antigen synthesis mutants and themore » O-antigen polymerization (wzy) mutants. Smooth isolates were also of two types, one producing low-molecular-weight (LMW) LPS and the other producing high-molecular-weight (HMW) LPS. To determine the genetic basis for the O-chain variability of the smooth isolates, the authors analyzed the effects of a null mutation in the O-chain length determinant gene, wzz (cld) of serovar Typhimurium. This mutation results in a loss of HMW LPS; however, the LMW LPS of this mutant was longer and more glucosylated than that from clinical isolates of serovar Enteritidis. Cluster analysis of these data and of those from two previously characterized isogenic strains of serovar Enteritidis that had different virulence attributes indicated that glucosylation of HMW LPS (via oafR function) is variable and results in two types of HMW structures, one that is highly glucosylated and one that is minimally glucosylated. These results strongly indicate that naturally occurring variability in wzy, wzz, and oafR function can be used to subtype isolates of serovar Enteritidis during epidemiological investigations.« less

Effects of leachate from crumb rubber and zinc in green roofs on the survival, growth, and resistance characteristics of Salmonella enterica subsp. enterica serovar Typhimurium.

PubMed

Crampton, Mollee; Ryan, Allayna; Eckert, Cori; Baker, Katherine H; Herson, Diane S

2014-05-01

The use of green roofs is a growing practice worldwide, particularly in densely populated areas. In an attempt to find new methods for recycling crumb rubber, incorporation of crumb rubber into artificial medium for plant growth in green roofs and similar engineered environments has become an attractive option for the recycling of waste tires. Though this approach decreases waste in landfills, there are concerns about the leaching of zinc and other heavy metals, as well as nutrient and organic compounds, into the environment. The present study analyzed the impact of leachate from crumb rubber and zinc on the growth and viability of Salmonella enterica subsp. enterica serovar Typhimurium. Zinc was chosen for further studies since it has been previously implicated with other biological functions, including biofilm formation, motility, and possible cross-resistance to antimicrobial agents. The study showed that Salmonella can colonize crumb rubber and that crumb rubber extract may provide nutrients that are usable by this bacterium. Salmonella strains with reduced susceptibility (SRS) to zinc were obtained after subculturing in increasing concentrations of zinc. The SRS exhibited differences in gene expression of flux pump genes zntA and znuA compared to that of the parent when exposed to 20 mM added zinc. In biofilm formation studies, the SRS formed less biofilm but was more motile than the parental strain.

Effects of Leachate from Crumb Rubber and Zinc in Green Roofs on the Survival, Growth, and Resistance Characteristics of Salmonella enterica subsp. enterica Serovar Typhimurium

PubMed Central

Crampton, Mollee; Ryan, Allayna; Eckert, Cori; Baker, Katherine H.

2014-01-01

The use of green roofs is a growing practice worldwide, particularly in densely populated areas. In an attempt to find new methods for recycling crumb rubber, incorporation of crumb rubber into artificial medium for plant growth in green roofs and similar engineered environments has become an attractive option for the recycling of waste tires. Though this approach decreases waste in landfills, there are concerns about the leaching of zinc and other heavy metals, as well as nutrient and organic compounds, into the environment. The present study analyzed the impact of leachate from crumb rubber and zinc on the growth and viability of Salmonella enterica subsp. enterica serovar Typhimurium. Zinc was chosen for further studies since it has been previously implicated with other biological functions, including biofilm formation, motility, and possible cross-resistance to antimicrobial agents. The study showed that Salmonella can colonize crumb rubber and that crumb rubber extract may provide nutrients that are usable by this bacterium. Salmonella strains with reduced susceptibility (SRS) to zinc were obtained after subculturing in increasing concentrations of zinc. The SRS exhibited differences in gene expression of flux pump genes zntA and znuA compared to that of the parent when exposed to 20 mM added zinc. In biofilm formation studies, the SRS formed less biofilm but was more motile than the parental strain. PMID:24584242

Variable Number of Tandem Repeats in Salmonella enterica subsp. enterica for Typing Purposes

PubMed Central

Ramisse, Vincent; Houssu, Perrine; Hernandez, Eric; Denoeud, France; Hilaire, Valérie; Lisanti, Olivier; Ramisse, Françoise; Cavallo, Jean-Didier; Vergnaud, Gilles

2004-01-01

The genomic sequences of Salmonella enterica subsp. enterica strains CT18, Ty2 (serovar Typhi), and LT2 (serovar Typhimurium) were analyzed for potential variable number tandem repeats (VNTRs). A multiple-locus VNTR analysis (MLVA) of 99 strains of S. enterica supsp. enterica based on 10 VNTRs distinguished 52 genotypes and placed them into four groups. All strains tested were independent human isolates from France and did not reflect isolates from outbreak episodes. Of these 10 VNTRs, 7 showed variability within serovar Typhi, whereas 1 showed variability within serovar Typhimurium. Four VNTRs showed high Nei's diversity indices (DIs) of 0.81 to 0.87 within serovar Typhi (n = 27). Additionally, three of these more variable VNTRs showed DIs of 0.18 to 0.58 within serovar Paratyphi A (n = 10). The VNTR polymorphic site within multidrug-resistant (MDR) serovar Typhimurium isolates (n = 39; resistance to ampicillin, chloramphenicol, spectinomycin, sulfonamides, and tetracycline) showed a DI of 0.81. Cluster analysis not only identified three genetically distinct groups consistent with the present serovar classification of salmonellae (serovars Typhi, Paratyphi A, and Typhimurium) but also discriminated 25 subtypes (93%) within serovar Typhi isolates. The analysis discriminated only eight subtypes within serovar Typhimurium isolates resistant to ampicillin, chloramphenicol, spectinomycin, sulfonamides, and tetracycline, possibly reflecting the emergence in the mid-1990s of the DT104 phage type, which often displays such an MDR spectrum. Coupled with the ongoing improvements in automated procedures offered by capillary electrophoresis, use of these markers is proposed in further investigations of the potential of MLVA in outbreaks of salmonellosis, especially outbreaks of typhoid fever. PMID:15583305

Multi-locus sequence typing of Salmonella enterica serovar Typhimurium isolates from wild birds in northern England suggests host-adapted strain.

PubMed

Hughes, L A; Wigley, P; Bennett, M; Chantrey, J; Williams, N

2010-10-01

Recent studies have suggested that Salmonella Typhimurium strains associated with mortality in UK garden birds are significantly different from strains that cause disease in humans and livestock and that wild bird strains may be host adapted. However, without further genomic characterization of these strains, it is not possible to determine whether they are host adapted. The aim of this study was to characterize a representative sample of Salm. Typhimurium strains detected in wild garden birds using multi-locus sequence typing (MLST)to investigate evolutionary relationships between them. Multi-locus sequence typing was performed on nine Salm. Typhimurium strains isolated from wild garden birds. Two sequence types were identified, the most common of which was ST568. Examination of the public Salmonella enterica MLST database revealed that only three other ST568 isolates had been cultured from a human in Scotland. Two further isolates of Salm. Typhimurium were determined to be ST19. Results of MLST analysis suggest that there is a predominant strain of Salm. Typhimurium circulating among garden bird populations in the United Kingdom, which is rarely detected in other species, supporting the hypothesis that this strain is host adapted. Host-pathogen evolution is often assumed to lead to pathogens becoming less virulent to avoid the death of their host; however, infection with ST568 led to high mortality rates among the wild birds examined, which were all found dead at wild bird-feeding stations. We hypothesize that by attracting unnaturally high densities of birds, wild bird-feeding stations may facilitate the transmission of ST568 between wild birds, therefore reducing the evolutionary cost of this pathogen killing its host, resulting in a host-adapted strain with increased virulence.

Sewage sludge amendment and inoculation with plant-parasitic nematodes do not facilitate the internalization of Salmonella Typhimurium LT2 in lettuce plants.

PubMed

Fornefeld, Eva; Baklawa, Mohamed; Hallmann, Johannes; Schikora, Adam; Smalla, Kornelia

2018-05-01

Contamination of fruits and vegetables with Salmonella is a serious threat to human health. In order to prevent possible contaminations of fresh produce it is necessary to identify the contributing ecological factors. In this study we investigated whether the addition of sewage sludge or the presence of plant-parasitic nematodes foster the internalization of Salmonella enterica serovar Typhimurium LT2 into lettuce plants, posing a potential threat for human health. Greenhouse experiments were conducted to investigate whether the amendment of sewage sludge to soil or the presence of plant-parasitic nematodes Meloidogyne hapla or Pratylenchus crenatus promote the internalization of S. Typhimurium LT2 from soil into the edible part of lettuce plants. Unexpectedly, numbers of cultivable S. Typhimurium LT2 decreased faster in soil with sewage sludge than in control soil but not in root samples. Denaturing gradient gel electrophoresis analysis revealed shifts of the soil bacterial communities in response to sewage sludge amendment and time. Infection and proliferation of nematodes inside plant roots were observed but did not influence the number of cultivable S. Typhimurium LT2 in the root samples or in soil. S. Typhimurium LT2 was not detected in the leaf samples 21 and 49 days after inoculation. The results indicate that addition of sewage sludge, M. hapla or P. crenatus to soil inoculated with S. Typhimurium LT2 did not result in an improved survival in soil or internalization of lettuce plants. Copyright © 2017. Published by Elsevier Ltd.

Antibacterial activity of crude extracts of some South African medicinal plants against multidrug resistant etiological agents of diarrhoea.

PubMed

Bisi-Johnson, Mary A; Obi, Chikwelu L; Samuel, Babatunde B; Eloff, Jacobus N; Okoh, Anthony I

2017-06-19

This study evaluated the antibacterial activity of some plants used in folklore medicine to treat diarrhoea in the Eastern Cape Province, South Africa. The acetone extracts of Acacia mearnsii De Wild., Aloe arborescens Mill., A. striata Haw., Cyathula uncinulata (Schrad.) Schinz, Eucomis autumnalis (Mill.) Chitt., E. comosa (Houtt.) Wehrh., Hermbstaedtia odorata (Burch. ex Moq.) T.Cooke, Hydnora africana Thunb, Hypoxis latifolia Wight, Pelargonium sidoides DC, Psidium guajava L and Schizocarphus nervosus (Burch.) van der Merwe were screened against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, multi-resistant Salmonella enterica serovar Isangi, S. typhi, S. enterica serovar Typhimurium, Shigella flexneri type 1b and Sh. sonnei phase II. A qualitative phytochemical screening of the plants extracts was by thin layer chromatography. Plants extracts were screened for antibacterial activity using serial dilution microplate technique and bioautography. The TLC fingerprint indicated the presence of terpenoids and flavonoids in the herbs. Most of the tested organisms were sensitive to the crude acetone extracts with minimum inhibitory concentration (MIC) values ranging from 0.018-2.5 mg/mℓ. Extracts of A. striata, C. uncinulata, E. autumnalis and P. guajava were more active against enteropathogens. S. aureus and Sh. flexneri were the most sensitive isolates to the crude extracts but of significance is the antibacterial activity of A. arborescens and P. guajava against a confirmed extended spectrum betalactamase positive S. enterica serovar Typhimurium. The presence of bioactive compounds and the antibacterial activity of some of the selected herbs against multidrug resistant enteric agents corroborate assertions by traditional healers on their efficacies.

Transfer of Salmonella enterica serovar Typhimurium from contaminated irrigation water to parsley is dependent on curli and cellulose, the biofilm matrix components.

PubMed

Lapidot, Anat; Yaron, Sima

2009-03-01

Enteric pathogens can contaminate fresh produce, and this contaminated produce can be a significant potential source of human illness. The objective of this study was to determine a possible mode of transfer of Salmonella Typhimurium from contaminated irrigation water to mature parsley plants and to investigate the role of bacterial cellulose and curli. Parsley plants were drip irrigated with water containing green fluorescent protein-labeled Salmonella Typhimurium. Stems and leaves were harvested 1 day after the third irrigation and examined for the presence of Salmonella Typhimurium. Three weeks after harvesting, the presence of Salmonella was again confirmed in the regrown plants. During this period, bacterial numbers on leaves declined from 4.1 (+/- 0.3) to 2.3 (+/- 0.1) log CFU g(-1) (P < 0.05). Numbers in the soil were constant (5 log CFU g(-1)). Results demonstrated the ability of Salmonella Typhimurium to transfer from irrigation water to the edible parts of the plants. Confocal laser scanning microscopic images revealed that Salmonella Typhimurium formed aggregates at a depth of 8 to 32 microm beneath the leaf surface. Penetration might be achieved through the roots or the phyllosphere. The importance of the bacterial cellulose and curli was determined by comparing the wild-type strain with its mutants, which lack the ability to synthesize cellulose and curli. Counts of the double mutant were 2-log higher in the soil but 1-log lower in the leaves (P < 0.05). Deletion of the agfBA gene (for curli) was more effective than deletion of bcsA (for cellulose). Thus, curli and cellulose play a role in the transfer or survival of Salmonella Typhimurium in the plant, as they do for plant pathogens.

Beneficial or Deleterious Effects of a Preexisting Hypersensitivity to Bacterial Components on the Course and Outcome of Infection

PubMed Central

Gumenscheimer, Marina; Mitov, Ivan; Galanos, Chris; Freudenberg, Marina A.

2002-01-01

Priming with heat-killed Propionibacterium acnes enhances the sensitivity of mice to lipopolysaccharide (LPS) and other biologically active bacterial components. We show that P. acnes priming has protective and deleterious effects on a subsequent serovar Typhimurium infection. It may result in a complete protection or prolonged survival, or it may accelerate mortality of the infected mice, depending on the number of serovar Typhimurium bacteria administered and on the degree of LPS hypersensitivity at the time of infection. Both effects of P. acnes-induced hypersensitivity are mediated by gamma interferon (IFN-γ) and are based on a differential activation of the innate immune mechanisms which recognize and react against the LPS present in infecting bacteria. In P. acnes-primed mice null for LPS-binding protein (LBP−/− mice), the impaired LPS recognition, due to the absence of LBP, resulted in a higher resistance to serovar Typhimurium infection. A similar P. acnes priming of mice had a protective, but no deleterious effect on a subsequent L. monocytogenes infection. This effect was IFN-γ dependent but independent of LBP. PMID:12228287

The agricultural antibiotic carbadox induces generalized transducing phage in multidrug-resistant Salmonella enterica serovar Typhimurium DT104

USDA-ARS?s Scientific Manuscript database

Non-typhoidal Salmonella, a leading cause of U.S. foodborne disease and food-related deaths, often asymptomatically colonizes food-producing animals. In fact, >50% of U.S. swine production facilities test positive for Salmonella. The multidrug-resistant (MDR) Salmonella Typhimurium DT104 NCTC13348 c...

Differential effects of rice bran cultivars to limit Salmonella Typhimurium in chicken cecal in vitro incubations and impact on the cecal microbiome and metabolome.

PubMed

Rubinelli, Peter M; Kim, Sun Ae; Park, Si Hong; Roto, Stephanie M; Nealon, Nora Jean; Ryan, Elizabeth P; Ricke, Steven C

2017-01-01

In this study, rice brans from different cultivars (Calrose, Jasmine, and Red Wells) were assessed for their ability to inhibit Salmonella enterica serovar Typhimurium using an in vitro mixed anaerobic culture system containing cecal microbiota obtained from broilers of different ages. Salmonella Typhimurium was added to controls (feed only, cecal only, and feed + cecal material) and treatments (feed + cecal + different rice brans) and S. Typhimurium populations were enumerated at 0, 24, and 48 h. Two experimental conditions were applied 1) unadapted condition in which S. Typhimurium was added at the beginning of the culture incubation and 2) adapted condition in which S. Typhimurium was added after a 24 hour pre-incubation of the cecal bacteria with the feed and/or rice bran. Among the three rice brans, only Calrose exhibited a rapid inhibition of S. Typhimurium, which decreased to undetectable levels after 24 h under the adapted incubation. Changes in microbiological composition and metabolites by addition of Calrose bran were also investigated with an Illumina MiSeq platform and gas chromatography-mass spectrometry, respectively. Addition of Calrose bran resulted in significant changes including decreased Firmicutes phylum abundance and an increased number of metabolites associated with fatty acid metabolism. In summary, it appears that rice bran from specific rice cultivars may be effective as a means to reduce Salmonella in the chicken ceca. In addition, Calrose rice bran inclusion leads to changes in cecal microbiological composition and metabolite profile.

Salmonella Typhimurium DT193 and DT99 are present in great and blue tits in Flanders, Belgium

PubMed Central

Verbrugghe, E.; Dekeukeleire, D.; De Beelde, R.; Rouffaer, L. O.; Haesendonck, R.; Strubbe, D.; Mattheus, W.; Bertrand, S.; Pasmans, F.; Bonte, D.; Verheyen, K.; Lens, L.; Martel, A.

2017-01-01

Endemic infections with the common avian pathogen Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium) may incur a significant cost on the host population. In this study, we determined the potential of endemic Salmonella infections to reduce the reproductive success of blue (Cyanistes caeruleus) and great (Parus major) tits by correlating eggshell infection with reproductive parameters. The fifth egg of each clutch was collected from nest boxes in 19 deciduous forest fragments. Out of the 101 sampled eggs, 7 Salmonella Typhimurium isolates were recovered. The low bacterial prevalence was reflected by a similarly low serological prevalence in the fledglings. In this study with a relatively small sample size, presence of Salmonella did not affect reproductive parameters (egg volume, clutch size, number of nestlings and number of fledglings), nor the health status of the fledglings. However, in order to clarify the impact on health and reproduction a larger number of samples have to be analyzed. Phage typing showed that the isolates belonged to the definitive phage types (DT) 193 and 99, and multi-locus variable number tandem repeat analysis (MLVA) demonstrated a high similarity among the tit isolates, but distinction to human isolates. These findings suggest the presence of passerine-adapted Salmonella strains in free-ranging tit populations with host pathogen co-existence. PMID:29112955

Infection with Salmonella enterica Serovar Typhimurium Leads to Increased Proportions of F4/80+ Red Pulp Macrophages and Decreased Proportions of B and T Lymphocytes in the Spleen.

PubMed

Rosche, Kristin L; Aljasham, Alanoud T; Kipfer, James N; Piatkowski, Bryan T; Konjufca, Vjollca

2015-01-01

Infection of mice with Salmonella enterica serovar Typhimurium (Salmonella) causes systemic inflammatory disease and enlargement of the spleen (splenomegaly). Splenomegaly has been attributed to a general increase in the numbers of phagocytes, lymphocytes, as well as to the expansion of immature CD71+Ter119+ reticulocytes. The spleen is important for recycling senescent red blood cells (RBCs) and for the capture and eradication of blood-borne pathogens. Conservation of splenic tissue architecture, comprised of the white pulp (WP), marginal zone (MZ), and red pulp (RP) is essential for initiation of adaptive immune responses to captured pathogens. Using flow cytometry and four color immunofluorescence microscopy (IFM), we show that Salmonella-induced splenomegaly is characterized by drastic alterations of the splenic tissue architecture and cell population proportions, as well as in situ cell distributions. A major cause of splenomegaly appears to be the significant increase in immature RBC precursors and F4/80+ macrophages that are important for recycling of heme-associated iron. In contrast, the proportions of B220+, CD4+ and CD8+ lymphocytes, as well as MZ MOMA+ macrophages decrease significantly as infection progresses. Spleen tissue sections show visible tears and significantly altered tissue architecture with F4/80+ macrophages and RBCs expanding beyond the RP and taking over most of the spleen tissue. Additionally, F4/80+ macrophages actively phagocytose not only RBCs, but also lymphocytes, indicating that they may contribute to declining lymphocyte proportions during Salmonella infection. Understanding how these alterations of spleen microarchitecture impact the generation of adaptive immune responses to Salmonella has implications for understanding Salmonella pathogenesis and for the design of more effective Salmonella-based vaccines.

The contribution of aerobic and anaerobic respiration to intestinal colonization and virulence for Salmonella typhimurium in the chicken.

PubMed

Barrow, Paul Andrew; Berchieri, Angelo; Freitas Neto, Oliveiro Caetano de; Lovell, Margaret

2015-10-01

The basic mechanism whereby Salmonella serovars colonize the chicken intestine remains poorly understood. Previous studies have indicated that proton-translocating proteins utilizing oxygen as terminal electron acceptor do not appear to be of major importance in the gut of the newly hatched chicken and consequently they would be even less significant during intestinal colonization of more mature chickens where the complex gut microflora would trap most of the oxygen in the lumen. Consequently, alternative electron acceptors may be more significant or, in their absence, substrate-level phosphorylation may also be important to Salmonella serovars in this environment. To investigate this we constructed mutants of Salmonella enterica serovar Typhimurium defective in various aspects of oxidative or substrate-level phosphorylation to assess their role in colonization of the chicken intestine, assessed through faecal shedding, and virulence. Mutations affecting use of oxygen or alternative electron acceptors did not eliminate faecal shedding. By contrast mutations in either pta (phosphotransacetylase) or ackA (acetate kinase) abolished shedding. The pta but not the ackA mutation also abolished systemic virulence for chickens. An additional ldhA (lactate dehydrogenase) mutant also showed poor colonizing ability. We hypothesise that substrate-level phosphorylation may be more important than respiration using oxygen or alternative electron acceptors for colonization of the chicken caeca.

Safety and tolerability of a live oral Salmonella typhimurium vaccine candidate in SIV-infected nonhuman primates.

PubMed

Ault, Alida; Tennant, Sharon M; Gorres, J Patrick; Eckhaus, Michael; Sandler, Netanya G; Roque, Annelys; Livio, Sofie; Bao, Saran; Foulds, Kathryn E; Kao, Shing-Fen; Roederer, Mario; Schmidlein, Patrick; Boyd, Mary Adetinuke; Pasetti, Marcela F; Douek, Daniel C; Estes, Jacob D; Nabel, Gary J; Levine, Myron M; Rao, Srinivas S

2013-12-02

Nontyphoidal Salmonella (NTS) serovars are a common cause of acute food-borne gastroenteritis worldwide and can cause invasive systemic disease in young infants, the elderly, and immunocompromised hosts, accompanied by high case fatality. Vaccination against invasive NTS disease is warranted where the disease incidence and mortality are high and multidrug resistance is prevalent, as in sub-Saharan Africa. Live-attenuated vaccines that mimic natural infection constitute one strategy to elicit protection. However, they must particularly be shown to be adequately attenuated for consideration of immunocompromised subjects. Accordingly, we examined the safety and tolerability of an oral live attenuated Salmonella typhimurium vaccine candidate, CVD 1921, in an established chronic simian immunodeficiency virus (SIV)-infected rhesus macaque model. We evaluated clinical parameters, histopathology, and measured differences in mucosal permeability to wild-type and vaccine strains. Compared to the wild-type S. typhimurium strain I77 in both SIV-infected and SIV-uninfected nonhuman primate hosts, this live-attenuated vaccine shows reduced shedding and systemic spread, exhibits limited pathological disease manifestations in the digestive tract, and induces low levels of cellular infiltration in tissues. Furthermore, wild-type S. typhimurium induces increased intestinal epithelial damage and permeability, with infiltration of neutrophils and macrophages in both SIV-infected and SIV-uninfected nonhuman primates compared to the vaccine strain. Based on shedding, systemic spread, and histopathology, the live-attenuated S. typhimurium strain CVD 1921 appears to be safe and well-tolerated in the nonhuman primate model, including chronically SIV-infected rhesus macaques. Copyright © 2013. Published by Elsevier Ltd.

Prime-boost immunization using a DNA vaccine delivered by attenuated Salmonella enterica serovar typhimurium and a killed vaccine completely protects chickens from H5N1 highly pathogenic avian influenza virus.

PubMed

Pan, Zhiming; Zhang, Xiaoming; Geng, Shizhong; Fang, Qiang; You, Meng; Zhang, Lei; Jiao, Xinan; Liu, Xiufan

2010-04-01

H5N1 highly pathogenic avian influenza virus (HPAIV) has posed a great threat not only for the poultry industry but also for human health. However, an effective vaccine to provide a full spectrum of protection is lacking in the poultry field. In the current study, a novel prime-boost vaccination strategy against H5N1 HPAIV was developed: chickens were first orally immunized with a hemagglutinin (HA) DNA vaccine delivered by attenuated Salmonella enterica serovar Typhimurium, and boosting with a killed vaccine followed. Chickens in the combined vaccination group but not in single vaccination and control groups were completely protected against disease following H5N1 HPAIV intranasal challenge, with no clinical signs and virus shedding. Chickens in the prime-boost group also generated significantly higher serum hemagglutination inhibition (HI) titers and intestinal mucosal IgA titers against avian influenza virus (AIV) and higher host immune cellular responses than those from other groups before challenge. These results demonstrated that the prime-boost vaccination strategy provides an effective way to prevent and control H5N1 highly pathogenic avian influenza virus.

Identification of Salmonella Typhimurium deubiquitinase SseL substrates by immunoaffinity enrichment and quantitative proteomic analysis

DOE PAGES

Nakayasu, Ernesto S.; Sydor, Michael A.; Brown, Roslyn N.; ...

2015-07-06

Ubiquitination is a key protein post-translational modification that regulates many important cellular pathways and whose levels are regulated by equilibrium between the activities of ubiquitin ligases and deubiquitinases. Here we present a method to identify specific deubiquitinase substrates based on treatment of cell lysates with recombinant enzymes, immunoaffinity purification and global quantitative proteomic analysis. As model system to identify substrates, we used a virulence-related deubiquitinase secreted by Salmonella enterica serovar Typhimurium into the host cells, SseL. By using this approach two SseL substrates were identified in RAW 264.7 murine macrophage-like cell line, S100A6 and het-erogeneous nuclear ribonuclear protein K, inmore » addition to the previously reported K63-linked ubiquitin chains. These substrates were further validated by a combination of enzymatic and binding assays. Finally, this method can be used for the systematic identification of substrates of deubiquitinases from other organisms and applied to study their functions in physiology and disease.« less

Identification of Salmonella Typhimurium deubiquitinase SseL substrates by immunoaffinity enrichment and quantitative proteomic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakayasu, Ernesto S.; Sydor, Michael A.; Brown, Roslyn N.

Ubiquitination is a key protein post-translational modification that regulates many important cellular pathways and whose levels are regulated by equilibrium between the activities of ubiquitin ligases and deubiquitinases. Here we present a method to identify specific deubiquitinase substrates based on treatment of cell lysates with recombinant enzymes, immunoaffinity purification and global quantitative proteomic analysis. As model system to identify substrates, we used a virulence-related deubiquitinase secreted by Salmonella enterica serovar Typhimurium into the host cells, SseL. By using this approach two SseL substrates were identified in RAW 264.7 murine macrophage-like cell line, S100A6 and het-erogeneous nuclear ribonuclear protein K, inmore » addition to the previously reported K63-linked ubiquitin chains. These substrates were further validated by a combination of enzymatic and binding assays. Finally, this method can be used for the systematic identification of substrates of deubiquitinases from other organisms and applied to study their functions in physiology and disease.« less

Expression, Extracellular Secretion, and Immunogenicity of the Plasmodium falciparum Sporozoite Surface Protein 2 in Salmonella Vaccine Strains

PubMed Central

Gómez-Duarte, Oscar G.; Pasetti, Marcela F.; Santiago, Araceli; Sztein, Marcelo B.; Hoffman, Stephen L.; Levine, Myron M.

2001-01-01

Deleting transmembrane α-helix motifs from Plasmodium falciparum sporozoite surface protein (SSP-2) allowed its secretion from Salmonella enterica serovar Typhimurium SL3261 and S. enterica serovar Typhi CVD 908-htrA by the Hly type I secretion system. In mice immunized intranasally, serovar Typhimurium constructs secreting SSP-2 stimulated greater gamma interferon splenocyte responses than did nonsecreting constructs (P = 0.04). PMID:11160021

An allele of an ancestral transcription factor dependent on a horizontally acquired gene product.

PubMed

Chen, H Deborah; Jewett, Mollie W; Groisman, Eduardo A

2012-01-01

Changes in gene regulatory circuits often give rise to phenotypic differences among closely related organisms. In bacteria, these changes can result from alterations in the ancestral genome and/or be brought about by genes acquired by horizontal transfer. Here, we identify an allele of the ancestral transcription factor PmrA that requires the horizontally acquired pmrD gene product to promote gene expression. We determined that a single amino acid difference between the PmrA proteins from the human adapted Salmonella enterica serovar Paratyphi B and the broad host range S. enterica serovar Typhimurium rendered transcription of PmrA-activated genes dependent on the PmrD protein in the former but not the latter serovar. Bacteria harboring the serovar Typhimurium allele exhibited polymyxin B resistance under PmrA- or under PmrA- and PmrD-inducing conditions. By contrast, isogenic strains with the serovar Paratyphi B allele displayed PmrA-regulated polymyxin B resistance only when experiencing activating conditions for both PmrA and PmrD. We establish that the two PmrA orthologs display quantitative differences in several biochemical properties. Strains harboring the serovar Paratyphi B allele showed enhanced biofilm formation, a property that might promote serovar Paratyphi B's chronic infection of the gallbladder. Our findings illustrate how subtle differences in ancestral genes can impact the ability of horizontally acquired genes to confer new properties.

Leaching of Cryptosporidium parvum Oocysts, Escherichia coli, and a Salmonella enterica Serovar Typhimurium Bacteriophage through Intact Soil Cores following Surface Application and Injection of Slurry▿

PubMed Central

Forslund, Anita; Markussen, Bo; Toenner-Klank, Lise; Bech, Tina B.; Jacobsen, Ole Stig; Dalsgaard, Anders

2011-01-01

Increasing amounts of livestock manure are being applied to agricultural soil, but it is unknown to what extent this may be associated with contamination of aquatic recipients and groundwater if microorganisms are transported through the soil under natural weather conditions. The objective of this study was therefore to evaluate how injection and surface application of pig slurry on intact sandy clay loam soil cores influenced the leaching of Salmonella enterica serovar Typhimurium bacteriophage 28B, Escherichia coli, and Cryptosporidium parvum oocysts. All three microbial tracers were detected in the leachate on day 1, and the highest relative concentration was detected on the fourth day (0.1 pore volume). Although the concentration of the phage 28B declined over time, the phage was still found in leachate at day 148. C. parvum oocysts and chloride had an additional rise in the relative concentration at a 0.5 pore volume, corresponding to the exchange of the total pore volume. The leaching of E. coli was delayed compared with that of the added microbial tracers, indicating a stronger attachment to slurry particles, but E. coli could be detected up to 3 months. Significantly enhanced leaching of phage 28B and oocysts by the injection method was seen, whereas leaching of the indigenous E. coli was not affected by the application method. Preferential flow was the primary transport vehicle, and the diameter of the fractures in the intact soil cores facilitated transport of all sizes of microbial tracers under natural weather conditions. PMID:21948848

New sub-family of lysozyme-like proteins shows no catalytic activity: crystallographic and biochemical study of STM3605 protein from Salmonella Typhimurium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michalska, Karolina; Brown, Roslyn N.; Li, Hui

Phage viruses that infect prokaryotes integrate their genome into the host chromosome; thus, microbial genomes typically contain genetic remnants of both recent and ancient phage infections. Often phage genes occur in clusters of atypical G+C content that reflect integration of the foreign DNA. However, some phage genes occur in isolation without other phage gene neighbors, probably resulting from horizontal gene transfer. In these cases, the phage gene product is unlikely to function as a component of a mature phage particle, and instead may have been co-opted by the host for its own benefit. The product of one such gene frommore » Salmonella enterica serovar Typhimurium, STM3605, encodes a protein with modest sequence similarity to phage-like lysozyme (N-acetylmuramidase) but appears to lack essential catalytic residues that are strictly conserved in all lysozymes. Close homologs in other bacteria share this characteristic. The structure of the STM3605 protein was characterized by X-ray crystallography, and functional assays showed that it is a stable, folded protein whose structure closely resembles lysozyme. However, this protein is unlikely to hydrolyze peptidoglycan. Instead, STM3605 is presumed to have evolved an alternative function because it shows some lytic activity and partitions to micelles.« less

Resveratrol induces membrane and DNA disruption via pro-oxidant activity against Salmonella typhimurium.

PubMed

Lee, Wonjong; Lee, Dong Gun

2017-07-22

Resveratrol is a flavonoid found in various plants including grapes, which has been reported to be active against various pathogenic bacteria. However, antibacterial effects and mechanisms via pro-oxidant property of resveratrol remain unknown and speculative. This research investigated antibacterial mechanism of resveratrol against a food-borne human pathogen Salmonella typhimurium, and confirmed the cell death associated oxidative damage. Resveratrol increased outer membrane permeability and membrane depolarization. It also was observed DNA injury responses such as DNA fragmentation, increasing DNA contents and cell division inhibition. Intracellular ROS accumulation, GSH depletion and significant increased malondialdehyde levels were confirmed, which indicated pro-oxidant activity of resveratrol and oxidative stress. Furthermore, the observed lethal damages were reduced by antioxidant N-acetylcysteine treatment supported the view that resveratrol-induced oxidative stress stimulated S. typhimurium cell death. In conclusion, this study expands understanding on role of pro-oxidant property and insight into previously unrecognized oxygen-dependent anti-Salmonella mechanism on resveratrol. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Holarrhena antidysentrica (Ha) and Andrographis paniculata (Ap) on the biofilm formation and cell membrane integrity of opportunistic pathogen Salmonella typhimurium.

PubMed

Tanwar, Ankit; Chawla, Raman; Chakotiya, Ankita Singh; Thakur, Pallavi; Goel, Rajeev; Basu, Mitra; Arora, Rajesh; Khan, Haider Ali

2016-12-01

Increasing occurrence of gastroenteritis outbreaks caused by food borne opportunistic microorganisms has become a major problem in food industry as well as in immunocompromised host. Antimicrobial agents are losing their efficacy due to increase in the microbial resistance. For such reasons, conventional treatment has become limited to manage the infections state. Need of the hour is to instigate the search for safer holistic alternatives. The present study was hence conducted to assess the antibiofilm effect and mode of action of aquo alcoholic extracts of Holarrhena antidysentrica (Ha) and Andrographis paniculata (Ap) against the Salmonella enterica serovar typhimurium. Both the extracts were screened for the presence of phytocompounds followed by the characterization using Attenuated Total Reflection (ATR) infrared spectroscopy and bioactivity finger print analysis. Anti-biofilm assays were determined to test the potential of both extracts to inhibit the biofilm formation, while Propidium Iodide (PI) uptake analysis revealed that cell membrane was damaged by the exposure of nutraceuticals for 1 h. This study has demonstrated that both nutraceuticals have anti-biofilm and antimicrobial activity perturbing the membrane integrity of food-borne S. typhimurium and could be used as curative remedy to control the food borne microbial infection. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microfluidic Chip-Based Detection and Intraspecies Strain Discrimination of Salmonella Serovars Derived from Whole Blood of Septic Mice

PubMed Central

Patterson, Adriana S.; Heithoff, Douglas M.; Ferguson, Brian S.; Soh, H. Tom; Mahan, Michael J.

2013-01-01

Salmonella is a zoonotic pathogen that poses a considerable public health and economic burden in the United States and worldwide. Resultant human diseases range from enterocolitis to bacteremia to sepsis and are acutely dependent on the particular serovar of Salmonella enterica subsp. enterica, which comprises over 99% of human-pathogenic S. enterica isolates. Point-of-care methods for detection and strain discrimination of Salmonella serovars would thus have considerable benefit to medical, veterinary, and field applications that safeguard public health and reduce industry-associated losses. Here we describe a single, disposable microfluidic chip that supports isothermal amplification and sequence-specific detection and discrimination of Salmonella serovars derived from whole blood of septic mice. The integrated microfluidic electrochemical DNA (IMED) chip consists of an amplification chamber that supports loop-mediated isothermal amplification (LAMP), a rapid, single-temperature amplification method as an alternative to PCR that offers advantages in terms of sensitivity, reaction speed, and amplicon yield. The amplification chamber is connected via a microchannel to a detection chamber containing a reagentless, multiplexed (here biplex) sensing array for sequence-specific electrochemical DNA (E-DNA) detection of the LAMP products. Validation of the IMED device was assessed by the detection and discrimination of S. enterica subsp. enterica serovars Typhimurium and Choleraesuis, the causative agents of enterocolitis and sepsis in humans, respectively. IMED chips conferred rapid (under 2 h) detection and discrimination of these strains at clinically relevant levels (<1,000 CFU/ml) from whole, unprocessed blood collected from septic animals. The IMED-based chip assay shows considerable promise as a rapid, inexpensive, and portable point-of-care diagnostic platform for the detection and strain-specific discrimination of microbial pathogens. PMID:23354710

A scalable method for O-antigen purification applied to various Salmonella serovars

PubMed Central

Micoli, F.; Rondini, S.; Gavini, M.; Pisoni, I.; Lanzilao, L.; Colucci, A.M.; Giannelli, C.; Pippi, F.; Sollai, L.; Pinto, V.; Berti, F.; MacLennan, C.A.; Martin, L.B.; Saul, A.

2014-01-01

The surface lipopolysaccharide of gram-negative bacteria is both a virulence factor and a B cell antigen. Antibodies against O-antigen of lipopolysaccharide may confer protection against infection, and O-antigen conjugates have been designed against multiple pathogens. Here, we describe a simplified methodology for extraction and purification of the O-antigen core portion of Salmonella lipopolysaccharide, suitable for large-scale production. Lipopolysaccharide extraction and delipidation are performed by acetic acid hydrolysis of whole bacterial culture and can take place directly in a bioreactor, without previous isolation and inactivation of bacteria. Further O-antigen core purification consists of rapid filtration and precipitation steps, without using enzymes or hazardous chemicals. The process was successfully applied to various Salmonella enterica serovars (Paratyphi A, Typhimurium, and Enteritidis), obtaining good yields of high-quality material, suitable for conjugate vaccine preparations. PMID:23142430

Attachment of Salmonella serovars and Listeria monocytogenes to stainless steel and plastic conveyor belts.

PubMed

Veluz, G A; Pitchiah, S; Alvarado, C Z

2012-08-01

In poultry industry, cross-contamination due to processing equipment and contact surfaces is very common. This study examined the extent of bacterial attachment to 6 different types and design of conveyor belts: stainless steel-single loop, stainless steel-balance weave, polyurethane with mono-polyester fabric, acetal, polypropylene mesh top, and polypropylene. Clean conveyor belts were immersed separately in either a cocktail of Salmonella serovars (Salmonella Typhimurium and Salmonella Enteritidis) or Listeria monocytogenes strains (Scott A, Brie 1, ATCC 6744) for 1 h at room temperature. Soiled conveyor chips were dipped in poultry rinses contaminated with Salmonella or Listeria cocktail and incubated at 10°C for 48 h. The polyurethane with mono-polyester fabric conveyor belt and chip exhibited a higher (P<0.05) mean number of attached Salmonella serovars (clean: 1.6 to 3.6 cfu/cm2; soiled: 0.8 to 2.4 cfu/cm2) and L. monocytogenes (clean: 4.0 to 4.3 cfu/cm2; soiled: 0.3 to 2.1 cfu/cm2) in both clean and soiled conditions. The stainless steel conveyor belt attached a lower (P<0.05) number of Salmonella serovars (clean: 0 to 2.6 cfu/cm2; soiled: 0.4 to 1.3 cfu/cm2) and L. monocytogenes (clean: 0.4 to 2.9 cfu/cm2; soiled: 0 to 0.7 cfu/cm2) than the polymeric materials, indicating weaker adhesion properties. Plastic conveyor belts exhibited stronger bacterial adhesion compared with stainless steel. The result suggests the importance of selecting the design and finishes of conveyor belt materials that are most resistant to bacterial attachment.

Salmonella DNA Adenine Methylase Mutants Confer Cross-Protective Immunity

PubMed Central

Heithoff, Douglas M.; Enioutina, Elena Y.; Daynes, Raymond A.; Sinsheimer, Robert L.; Low, David A.; Mahan, Michael J.

2001-01-01

Salmonella isolates that lack or overproduce DNA adenine methylase (Dam) elicited a cross-protective immune response to different Salmonella serovars. The protection afforded by the Salmonella enterica serovar Typhimurium Dam vaccine was greater than that elicited in mice that survived a virulent infection. S. enterica serovar Typhimurium Dam mutant strains exhibited enhanced sensitivity to mediators of innate immunity such as antimicrobial peptides, bile salts, and hydrogen peroxide. Also, S. enterica serovar Typhimurium Dam− vaccines were not immunosuppressive; unlike wild-type vaccines, they failed to induce increased nitric oxide levels and permitted a subsequent robust humoral response to diptheria toxoid antigen in infected mice. Dam mutant strains exhibited a low-grade persistence which, coupled with the nonimmunosuppression and the ectopic protein expression caused by altered levels of Dam, may provide an expanded source of potential antigens in vaccinated hosts. PMID:11598044

Identification of new loci involved in the host susceptibility to Salmonella Typhimurium in collaborative cross mice.

PubMed

Zhang, Jing; Malo, Danielle; Mott, Richard; Panthier, Jean-Jacques; Montagutelli, Xavier; Jaubert, Jean

2018-04-27

Salmonella is a Gram-negative bacterium causing a wide range of clinical syndromes ranging from typhoid fever to diarrheic disease. Non-typhoidal Salmonella (NTS) serovars infect humans and animals, causing important health burden in the world. Susceptibility to salmonellosis varies between individuals under the control of host genes, as demonstrated by the identification of over 20 genetic loci in various mouse crosses. We have investigated the host response to S. Typhimurium infection in 35 Collaborative Cross (CC) strains, a genetic population which involves wild-derived strains that had not been previously assessed. One hundred and forty-eight mice from 35 CC strains were challenged intravenously with 1000 colony-forming units (CFUs) of S. Typhimurium. Bacterial load was measured in spleen and liver at day 4 post-infection. CC strains differed significantly (P < 0.0001) in spleen and liver bacterial loads, while sex and age had no effect. Two significant quantitative trait loci (QTLs) on chromosomes 8 and 10 and one suggestive QTL on chromosome 1 were found for spleen bacterial load, while two suggestive QTLs on chromosomes 6 and 17 were found for liver bacterial load. These QTLs are caused by distinct allelic patterns, principally involving alleles originating from the wild-derived founders. Using sequence variations between the eight CC founder strains combined with database mining for expression in target organs and known immune phenotypes, we were able to refine the QTLs intervals and establish a list of the most promising candidate genes. Furthermore, we identified one strain, CC042/GeniUnc (CC042), as highly susceptible to S. Typhimurium infection. By exploring a broader genetic variation, the Collaborative Cross population has revealed novel loci of resistance to Salmonella Typhimurium. It also led to the identification of CC042 as an extremely susceptible strain.

The agricultural antibiotic carbadox induces prophage and antibiotic resistance gene transfer in multidrug-resistant salmonella enterica serovar typhimurium DT104

USDA-ARS?s Scientific Manuscript database

Non-typhoidal Salmonella strains cause ~1 million cases of foodborne disease each year in the U.S. and are a leading cause of food-related deaths. The prevalence of multidrug-resistant (MDR) Salmonella serovars has increased over the last few decades, and infection with these strains has an increase...

Transfer of Salmonella enterica Serovar Typhimurium from Beef to Tomato through Kitchen Equipment and the Efficacy of Intermediate Decontamination Procedures.

PubMed

Gkana, E; Lianou, A; Nychas, G-J E

2016-07-01

It is well established that a high percentage of foodborne illness is caused by failure of consumers to prepare food in a hygienic manner. Indeed, a common practice in households is to use the same kitchen equipment for both raw meat and fresh produce. Such a practice may lead to cross-contamination of fruits and vegetables, which are mainly consumed without further processing, with pathogenic microorganisms originating from raw meat. The present study was performed to examine the transfer of the pathogenic bacterium Salmonella enterica serovar Typhimurium from inoculated beef fillets to tomatoes via contact with high-density polyethylene (PE), stainless steel (SS), and wooden (WD) surfaces and through cutting with SS knives. Furthermore, the following decontamination procedures were applied: (i) rinsing with tap water, (ii) scrubbing with tap water and liquid dish detergent, and (iii) using a commercial antibacterial spray. When surfaces and knives that came into contact with contaminated beef fillets were not cleaned prior to handling tomatoes, the lowest level of pathogen transfer to tomatoes was observed through PE surfaces. All of the decontamination procedures applied were more effective on knives than on surfaces, while among the surface materials tested, WD surfaces were the most difficult to decontaminate, followed by PE and SS surfaces. Mechanical cleaning with tap water and detergent was more efficient in decontaminating WD surfaces than using commercial disinfectant spray, followed by rinsing only with water. Specifically, reductions of 2.07 and 1.09 log CFU/cm(2) were achieved by washing the WD surfaces with water and detergent and spraying the surfaces with an antibacterial product, respectively. Although the pathogen's populations on SS and PE surfaces, as well as on tomatoes, after both aforementioned treatments were under the detection limit, the surfaces were all positive after enrichment, and thus, the potential risk of cross-contamination cannot

Salmonella Typhimurium induces SPI-1 and SPI-2 regulated and strain dependent downregulation of MHC II expression on porcine alveolar macrophages

PubMed Central

2012-01-01

Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella Typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Circumvention of the host’s immune system by Salmonella might contribute to persistent infection of pigs. In the present study, we found that Salmonella Typhimurium strain 112910a specifically downregulated MHC II, but not MHC I, expression on porcine alveolar macrophages in a Salmonella pathogenicity island (SPI)-1 and SPI-2 dependent way. Salmonella induced downregulation of MHC II expression and intracellular proliferation of Salmonella in macrophages were significantly impaired after opsonization with Salmonella specific antibodies prior to inoculation. Furthermore, the capacity to downregulate MHC II expression on macrophages differed significantly among Salmonella strains, independently of strain specific differences in invasion capacity, Salmonella induced cytotoxicity and altered macrophage activation status. The fact that strain specific differences in MHC II downregulation did not correlate with the extent of in vitro SPI-1 or SPI-2 gene expression indicates that other factors are involved in MHC II downregulation as well. Since Salmonella strain dependent interference with the pig’s immune response through downregulation of MHC II expression might indicate that certain Salmonella strains are more likely to escape serological detection, our findings are of major interest for Salmonella monitoring programs primarily based on serology. PMID:22694285

A Phylogenetic and Phenotypic Analysis of Salmonella enterica Serovar Weltevreden, an Emerging Agent of Diarrheal Disease in Tropical Regions

PubMed Central

Makendi, Carine; Page, Andrew J.; Wren, Brendan W.; Le Thi Phuong, Tu; Clare, Simon; Hale, Christine; Goulding, David; Klemm, Elizabeth J.; Pickard, Derek; Okoro, Chinyere; Hunt, Martin; Thompson, Corinne N.; Phu Huong Lan, Nguyen; Tran Do Hoang, Nhu; Thwaites, Guy E.; Le Hello, Simon; Brisabois, Anne; Weill, François-Xavier; Baker, Stephen; Dougan, Gordon

2016-01-01

Salmonella enterica serovar Weltevreden (S. Weltevreden) is an emerging cause of diarrheal and invasive disease in humans residing in tropical regions. Despite the regional and international emergence of this Salmonella serovar, relatively little is known about its genetic diversity, genomics or virulence potential in model systems. Here we used whole genome sequencing and bioinformatics analyses to define the phylogenetic structure of a diverse global selection of S. Weltevreden. Phylogenetic analysis of more than 100 isolates demonstrated that the population of S. Weltevreden can be segregated into two main phylogenetic clusters, one associated predominantly with continental Southeast Asia and the other more internationally dispersed. Subcluster analysis suggested the local evolution of S. Weltevreden within specific geographical regions. Four of the isolates were sequenced using long read sequencing to produce high quality reference genomes. Phenotypic analysis in Hep-2 cells and in a murine infection model indicated that S. Weltevreden were significantly attenuated in these models compared to the classical S. Typhimurium reference strain SL1344. Our work outlines novel insights into this important emerging pathogen and provides a baseline understanding for future research studies. PMID:26867150

Determination of Leptospira borgpetersenii serovar Javanica and Leptospira interrogans serovar Bataviae as the persistent Leptospira serovars circulating in the urban rat populations in Peninsular Malaysia.

PubMed

Benacer, Douadi; Mohd Zain, Siti Nursheena; Sim, Shin Zhu; Mohd Khalid, Mohd Khairul Nizam; Galloway, Renee L; Souris, Marc; Thong, Kwai Lin

2016-03-01

Leptospirosis is an emerging infectious disease of global significance, and is endemic in tropical countries, including Malaysia. Over the last decade, a dramatic increase of human cases was reported; however, information on the primary vector, the rat, and the Leptospira serovars circulating among the rat population is limited. Therefore, the present study was undertaken to isolate Leptospira and characterise the serovars circulating in the urban rat populations from selected main cities in Peninsular Malaysia. Rat trappings were carried out between October 2011 to February 2014 in five urban cities which were chosen as study sites to represent different geographical locations in Peninsular Malaysia. Microscopic agglutination test (MAT) and PCR were carried out to identify the Leptospiral serogroup and determine the pathogenic status of the isolates, respectively while pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD)-PCR were used to characterize the isolates. Three rat species were identified from the three hundred and fifty seven rats captured with Rattus rattus, being the dominant rat species (285, 80 %) followed by Rattus norgevicus (53, 15 %) and Rattus exulans (19, 5 %). Only 39 samples (11.0 %) were positive by culture and further confirmed as pathogenic Leptospira by PCR. Significant associations were shown between host infection with locality, season, host-age and species. Based on MAT, two serogroups were identified in the population namely; L. borgpetersenii serogroup Javanica (n = 16) and L. interrogans serogroup Bataviae (n = 23). Pulsed-field gel electrophoresis (PFGE) distinguished the two serovars in the urban rat populations: L. borgpetersenii serovar Javanica (41 %), and L. interrogans serovar Bataviae (59 %). RAPD-PCR yielded 14 distinct patterns and was found to be more discriminative than PFGE. This study confirms two Leptospira serovars circulating among the urban rats population in Peninsular

Inactivation of Bacillus cereus and Salmonella enterica serovar Typhimurium by aqueous ozone (O3): Modeling and Uv-Vis spectroscopic analysis

USDA-ARS?s Scientific Manuscript database

Ozone (O3) is a natural antimicrobial agent with potential applications in food industry. In this study, inactivation of Bacillus cereus and Salmonella enterica Typhimurium by aqueous ozone was evaluated. Ozone gas was generated using a domestic ozone generator with an output of 200 mg/hr (approx. 0...

Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding

PubMed Central

Balakrishnan, Arjun; Negi, Vidya Devi; Sakorey, Deepika; Chandra, Nagasuma

2016-01-01

ABSTRACT One of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an “Achilles heel,” revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility of Salmonella, a foodborne pathogen. It reduced the motility of Salmonella enterica serovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175. IMPORTANCE This work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important

Salmonella Typhimurium disrupts Sirt1/AMPK checkpoint control of mTOR to impair autophagy

PubMed Central

Ganesan, Raja; Hos, Nina Judith; Gutierrez, Saray; Fischer, Julia; Stepek, Joanna Magdalena; Daglidu, Evmorphia; Krönke, Martin

2017-01-01

During intracellular infections, autophagy significantly contributes to the elimination of pathogens, regulation of pro-inflammatory signaling, secretion of immune mediators and in coordinating the adaptive immune system. Intracellular pathogens such as S. Typhimurium have evolved mechanisms to circumvent autophagy. However, the regulatory mechanisms targeted by S. Typhimurium to modulate autophagy have not been fully resolved. Here we report that cytosolic energy loss during S. Typhimurium infection triggers transient activation of AMPK, an important checkpoint of mTOR activity and autophagy. The activation of AMPK is regulated by LKB1 in a cytosolic complex containing Sirt1 and LKB1, where Sirt1 is required for deacetylation and subsequent activation of LKB1. S. Typhimurium infection targets Sirt1, LKB1 and AMPK to lysosomes for rapid degradation resulting in the disruption of the AMPK-mediated regulation of mTOR and autophagy. The degradation of cytosolic Sirt1/LKB1/AMPK complex was not observed with two mutant strains of S. Typhimurium, ΔssrB and ΔssaV, both compromising the pathogenicity island 2 (SPI2). The results highlight virulence factor-dependent degradation of host cell proteins as a previously unrecognized strategy of S. Typhimurium to evade autophagy. PMID:28192515

Inactivation of Escherichia coli O157:H7, Salmonella typhimurium DT104, and Listeria monocytogenes on inoculated alfalfa seeds with a fatty acid-based sanitizer.

PubMed

Pierre, Pascale M; Ryser, Elliot T

2006-03-01

Alfalfa seeds were inoculated with a three-strain cocktail of Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Typhimurium DT104, or Listeria monocytogenes by immersion to contain approximately 6 to 8 log CFU/g and then treated with a fatty acid-based sanitizer containing 250 ppm of peroxyacid, 1,000 ppm of caprylic and capric acids (Emery 658), 1,000 ppm of lactic acid, and 500 ppm of glycerol monolaurate at a reference concentration of 1X. Inoculated seeds were immersed at sanitizer concentrations of 5X, 10X, and 15X for 1, 3, 5, and 10 min and then assessed for pathogen survivors by direct plating. The lowest concentration that decreased all three pathogens by >5 log was 15. After a 3-min exposure to the 15X concentration, populations of E. coli O157:H7, Salmonella Typhimurium DT104, and L. monocytogenes decreased by >5.45, >5.62, and >6.92 log, respectively, with no sublethal injury and no significant loss in seed germination rate or final sprout yield. The components of this 15x concentration (treatment A) were assessed independently and in various combinations to optimize antimicrobial activity. With inoculated seeds, treatment C (15,000 ppm of Emery 658, 15,000 ppm of lactic acid, and 7,500 ppm of glycerol monolaurate) decreased Salmonella Typhimurium, E. coli O157:H7, and L. monocytogenes by 6.23 and 5.57 log, 4.77 and 6.29 log, and 3.86 and 4.21 log after 3 and 5 min of exposure, respectively. Treatment D (15,000 ppm of Emery 658 and 15,000 ppm of lactic acid) reduced Salmonella Typhimurium by >6.90 log regardless of exposure time and E. coli )157:H7 and L. monocytogenes by 4.60 and >5.18 log and 3.55 and 3.14 log after 3 and 5 min, respectively. No significant differences (P > 0.05) were found between treatments A, C, and D. Overall, treatment D, which contained Emery 658 and lactic acid as active ingredients, reduced E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes populations by 3.55 to >6.90 log and may provide a

Development of a glycoconjugate vaccine to prevent invasive Salmonella Typhimurium infections in sub-Saharan Africa

PubMed Central

Baliban, Scott M.; Yang, Mingjun; Ramachandran, Girish; Curtis, Brittany; Shridhar, Surekha; Laufer, Rachel S.; Wang, Jin Y.; Van Druff, John; Higginson, Ellen E.; Hegerle, Nicolas; Varney, Kristen M.; Galen, James E.; Tennant, Sharon M.; Lees, Andrew; MacKerell, Alexander D.; Levine, Myron M.; Simon, Raphael

2017-01-01

Invasive infections associated with non-typhoidal Salmonella (NTS) serovars Enteritidis (SE), Typhimurium (STm) and monophasic variant 1,4,[5],12:i:- are a major health problem in infants and young children in sub-Saharan Africa, and currently, there are no approved human NTS vaccines. NTS O-polysaccharides and flagellin proteins are protective antigens in animal models of invasive NTS infection. Conjugates of SE core and O-polysaccharide (COPS) chemically linked to SE flagellin have enhanced the anti-COPS immune response and protected mice against fatal challenge with a Malian SE blood isolate. We report herein the development of a STm glycoconjugate vaccine comprised of STm COPS conjugated to the homologous serovar phase 1 flagellin protein (FliC) with assessment of the role of COPS O-acetyls for functional immunity. Sun-type COPS conjugates linked through the polysaccharide reducing end to FliC were more immunogenic and protective in mice challenged with a Malian STm blood isolate than multipoint lattice conjugates (>95% vaccine efficacy [VE] versus 30–43% VE). Immunization with de-O-acetylated STm-COPS conjugated to CRM197 provided significant but reduced protection against STm challenge compared to mice immunized with native STm-COPS:CRM197 (63–74% VE versus 100% VE). Although OPS O-acetyls were highly immunogenic, post-vaccination sera that contained various O-acetyl epitope-specific antibody profiles displayed similar in vitro bactericidal activity when equivalent titers of anti-COPS IgG were assayed. In-silico molecular modeling further indicated that STm OPS forms a single dominant conformation, irrespective of O-acetylation, in which O-acetyls extend outward and are highly solvent exposed. These preclinical results establish important quality attributes for an STm vaccine that could be co-formulated with an SE-COPS:FliC glycoconjugate as a bivalent NTS vaccine for use in sub-Saharan Africa. PMID:28388624

Development of a glycoconjugate vaccine to prevent invasive Salmonella Typhimurium infections in sub-Saharan Africa.

PubMed

Baliban, Scott M; Yang, Mingjun; Ramachandran, Girish; Curtis, Brittany; Shridhar, Surekha; Laufer, Rachel S; Wang, Jin Y; Van Druff, John; Higginson, Ellen E; Hegerle, Nicolas; Varney, Kristen M; Galen, James E; Tennant, Sharon M; Lees, Andrew; MacKerell, Alexander D; Levine, Myron M; Simon, Raphael

2017-04-01

Invasive infections associated with non-typhoidal Salmonella (NTS) serovars Enteritidis (SE), Typhimurium (STm) and monophasic variant 1,4,[5],12:i:- are a major health problem in infants and young children in sub-Saharan Africa, and currently, there are no approved human NTS vaccines. NTS O-polysaccharides and flagellin proteins are protective antigens in animal models of invasive NTS infection. Conjugates of SE core and O-polysaccharide (COPS) chemically linked to SE flagellin have enhanced the anti-COPS immune response and protected mice against fatal challenge with a Malian SE blood isolate. We report herein the development of a STm glycoconjugate vaccine comprised of STm COPS conjugated to the homologous serovar phase 1 flagellin protein (FliC) with assessment of the role of COPS O-acetyls for functional immunity. Sun-type COPS conjugates linked through the polysaccharide reducing end to FliC were more immunogenic and protective in mice challenged with a Malian STm blood isolate than multipoint lattice conjugates (>95% vaccine efficacy [VE] versus 30-43% VE). Immunization with de-O-acetylated STm-COPS conjugated to CRM197 provided significant but reduced protection against STm challenge compared to mice immunized with native STm-COPS:CRM197 (63-74% VE versus 100% VE). Although OPS O-acetyls were highly immunogenic, post-vaccination sera that contained various O-acetyl epitope-specific antibody profiles displayed similar in vitro bactericidal activity when equivalent titers of anti-COPS IgG were assayed. In-silico molecular modeling further indicated that STm OPS forms a single dominant conformation, irrespective of O-acetylation, in which O-acetyls extend outward and are highly solvent exposed. These preclinical results establish important quality attributes for an STm vaccine that could be co-formulated with an SE-COPS:FliC glycoconjugate as a bivalent NTS vaccine for use in sub-Saharan Africa.

Isolation of Salmonella enterica serovar Enteritidis from houseflies (Musca domestica) found in rooms containing Salmonella serovar Enteritidis-challenged hens.

PubMed

Holt, Peter S; Geden, Christopher J; Moore, Randle W; Gast, Richard K

2007-10-01

Houseflies (Musca domestica) released into rooms containing hens challenged with Salmonella enterica serovar Enteritidis (Salmonella serovar Enteritidis) rapidly became contaminated with Salmonella serovar Enteritidis. Forty to 50% of the flies were contaminated at 48 h, and the percentage increased to 50 to 70% at 4 and 7 days postexposure and then decreased to 30% at day 15. Initial attempts at recovering surface organisms for culture using an aqueous rinse were largely unsuccessful, while cultures of internal contents readily recovered Salmonella serovar Enteritidis. However, when 0.5% detergent was incorporated into the rinse, high recovery levels of bacteria were observed from both external and internal culture regimens, indicating equal distribution of the organism on and in the fly and a tighter interaction of the organism with the host than previously thought. Salmonella serovar Enteritidis was isolated routinely from the fly gut, on rare occasions from the crop, and never from the salivary gland. Feeding contaminated flies to hens resulted in gut colonization of a third of the birds, but release of contaminated flies in a room containing previously unchallenged hens failed to result in colonization of any of the subject birds. These results indicate that flies exposed to an environment containing Salmonella serovar Enteritidis can become colonized with the organism and might serve as a source for transmission of Salmonella serovar Enteritidis within a flock situation.

Isolation of Salmonella enterica Serovar Enteritidis from Houseflies (Musca domestica) Found in Rooms Containing Salmonella Serovar Enteritidis-Challenged Hens▿

PubMed Central

Holt, Peter S.; Geden, Christopher J.; Moore, Randle W.; Gast, Richard K.

2007-01-01

Houseflies (Musca domestica) released into rooms containing hens challenged with Salmonella enterica serovar Enteritidis (Salmonella serovar Enteritidis) rapidly became contaminated with Salmonella serovar Enteritidis. Forty to 50% of the flies were contaminated at 48 h, and the percentage increased to 50 to 70% at 4 and 7 days postexposure and then decreased to 30% at day 15. Initial attempts at recovering surface organisms for culture using an aqueous rinse were largely unsuccessful, while cultures of internal contents readily recovered Salmonella serovar Enteritidis. However, when 0.5% detergent was incorporated into the rinse, high recovery levels of bacteria were observed from both external and internal culture regimens, indicating equal distribution of the organism on and in the fly and a tighter interaction of the organism with the host than previously thought. Salmonella serovar Enteritidis was isolated routinely from the fly gut, on rare occasions from the crop, and never from the salivary gland. Feeding contaminated flies to hens resulted in gut colonization of a third of the birds, but release of contaminated flies in a room containing previously unchallenged hens failed to result in colonization of any of the subject birds. These results indicate that flies exposed to an environment containing Salmonella serovar Enteritidis can become colonized with the organism and might serve as a source for transmission of Salmonella serovar Enteritidis within a flock situation. PMID:17675422

TTSS2-deficient hha mutant of Salmonella Typhimurium exhibits significant systemic attenuation in immunocompromised hosts

PubMed Central

Vishwakarma, Vikalp; Pati, Niladri Bhusan; Ray, Shilpa; Das, Susmita; Suar, Mrutyunjay

2014-01-01

Non-typhoidal Salmonella (NTS) infections are emerging as leading problem worldwide and the variations in host immune status append to the concern of NTS. Salmonella enterica serovar Typhimurium is one of the causative agents of NTS infections and has been extensively studied. The inactivation of Salmonella pathogenicity island 2 (SPI2) encoded type-III secretion system 2 (TTSS2) has been reported rendering the strain incapable for systemic dissemination to host sites and has also been proposed as live-attenuated vaccine. However, infections from TTSS2-deficient Salmonella have also been reported. In this study, mutant strain MT15 was developed by inactivation of the hemolysin expression modulating protein (hha) in TTSS2-deficient S. Typhimurium background. The MT15 strain showed significant level of attenuation in immune-deprived murine colitis model when tested in iNos−/−, IL10−/−, and CD40L−/− mice groups in C57BL/6 background. Further, the mutation in hha does not implicate any defect in bacterial colonization to the host gut. The long-term infection of developed mutant strain conferred protective immune responses to suitably immunized streptomycin pre-treated C57BL/6 mice. The immunization enhanced the CD4+ and CD8+ cell types involved in bacterial clearance. The serum IgG and luminal secretory IgA (sIgA) was also found to be elevated after the due course of infection. Additionally, the immunized C57BL/6 mice were protected from the subsequent lethal infection of Salmonella Typhimurium. Collectively, these findings implicate the involvement of hemolysin expression modulating protein (Hha) in establishment of bacterial infection. In light of the observed attenuation of the developed mutant strain, this study proposes the possible significance of SPI2-deficient hha mutant as an alternative live-attenuated vaccine strain for use against lethal Salmonella infections. PMID:24401482

Salmonella enterica: Survival, Colonization, and Virulence Differences among Serovars

PubMed Central

Andino, A.; Hanning, I.

2015-01-01

Data indicate that prevalence of specific serovars of Salmonella enterica in human foodborne illness is not correlated with their prevalence in feed. Given that feed is a suboptimal environment for S. enterica, it appears that survival in poultry feed may be an independent factor unrelated to virulence of specific serovars of Salmonella. Additionally, S. enterica serovars appear to have different host specificity and the ability to cause disease in those hosts is also serovar dependent. These differences among the serovars may be related to gene presence or absence and expression levels of those genes. With a better understanding of serovar specificity, mitigation methods can be implemented to control Salmonella at preharvest and postharvest levels. PMID:25664339

Sublethal Exposure to Commercial Formulations of the Herbicides Dicamba, 2,4-Dichlorophenoxyacetic Acid, and Glyphosate Cause Changes in Antibiotic Susceptibility in Escherichia coli and Salmonella enterica serovar Typhimurium

PubMed Central

Kurenbach, Brigitta; Marjoshi, Delphine; Amábile-Cuevas, Carlos F.; Ferguson, Gayle C.; Godsoe, William; Gibson, Paddy

2015-01-01

ABSTRACT Biocides, such as herbicides, are routinely tested for toxicity but not for sublethal effects on microbes. Many biocides are known to induce an adaptive multiple-antibiotic resistance phenotype. This can be due to either an increase in the expression of efflux pumps, a reduced synthesis of outer membrane porins, or both. Exposures of Escherichia coli and Salmonella enterica serovar Typhimurium to commercial formulations of three herbicides—dicamba (Kamba), 2,4-dichlorophenoxyacetic acid (2,4-D), and glyphosate (Roundup)—were found to induce a changed response to antibiotics. Killing curves in the presence and absence of sublethal herbicide concentrations showed that the directions and the magnitudes of responses varied by herbicide, antibiotic, and species. When induced, MICs of antibiotics of five different classes changed up to 6-fold. In some cases the MIC increased, and in others it decreased. Herbicide concentrations needed to invoke the maximal response were above current food maximum residue levels but within application levels for all herbicides. Compounds that could cause induction had additive effects in combination. The role of soxS, an inducer of the AcrAB efflux pump, was tested in β-galactosidase assays with soxS-lacZ fusion strains of E. coli. Dicamba was a moderate inducer of the sox regulon. Growth assays with Phe-Arg β-naphtylamide (PAβN), an efflux pump inhibitor, confirmed a significant role of efflux in the increased tolerance of E. coli to chloramphenicol in the presence of dicamba and to kanamycin in the presence of glyphosate. Pathways of exposure with relevance to the health of humans, domestic animals, and critical insects are discussed. PMID:25805724

Subinhibitory concentrations of phloretin repress the virulence of Salmonella typhimurium and protect against Salmonella typhimurium infection.

PubMed

Shuai-Cheng, Wu; Ben-Dong, Fu; Xiu-Ling, Chu; Jian-Qing, Su; Yun-Xing, Fu; Zhen-Qiang, Cui; Dao-Xiu, Xu; Zong-Mei, Wu

2016-11-01

Phloretin, a natural component of many fruits, exhibits anti-virulence effects and provides a new alternative to counter bacterial infection. The aim of this study was to determine the effect of subinhibitory concentrations of phloretin on the virulence of Salmonella typhimurium. At concentrations where growth of Salmonella was not inhibited, phloretin significantly inhibited bacteria biofilm formation and motility. Subinhibitory concentrations of phloretin repressed eight genes involved in the Salmonella pathogenicity island 1 and 3 genes involved in flagella production. Furthermore, subinhibitory concentrations of phloretin inhibited the adhesion and invasion of Salmonella in IEC-6 cells and reduced the LDH levels of S. typhimurium-infected IEC-6 cells. Additionally, phloretin significantly decreased the cecum bacterial loads of the mice infected with live S. typhimurium containing subinhibitory concentrations of phloretin by gavage. These results suggested that subinhibitory concentrations of phloretin attenuate the virulence of S. typhimurium and protect against S. typhimurium infection.

Comparison of 7 culture methods for Salmonella serovar Enteritidis and Salmonella serovar Typhimurium isolation in poultry feces.

PubMed

Rodríguez, Francisco I; Procura, Francisco; Bueno, Dante J

2018-06-26

The present work compared 7 different culture methods and 3 selective-differential plating media for Salmonella ser. Enteritidis (SE) and S. ser. Typhimurium (ST) isolation using artificially contaminated poultry feces. The sensitivity (Se) and accuracy (AC) values increased when Modified Semisolid Rappaport Vassiliadis (MSRV) methods were used in place of the Tetrathionate (TT) or Tetrathionate Hajna broth (TTH) method in the enrichment step. However, there was no significant difference between the pre-enrichment incubation at 4 to 6 and 18 to 24 h for MSRV5 and MSRV24 methods, respectively. All Salmonella strains were recovered in the lowest dilutions tested for MSRV24 and 3 out of 4 for MSRV5 methods (2 to 10 cfu/25 g). The TT and TTH methods showed a detection limit between 2.2 × 101 and 1.0 × 106 cfu/25 g of fecal sample. The agreement was variable between the methods. However, there was a very good agreement between the MSRV5 and MSRV24 methods, and between tetrathionate direct (TTD, no pre-enrichment media used) and buffered peptone water 18 to 24 h Tetrathionate broth combination (TT24 method) for Salmonella strains. The 3 selective-differential plating media showed an agreement between fair and excellent. They performed a high Se and AC in the MSRV methods for Salmonella strains. There was a significant difference between center and periphery for MSRV methods, and there was a fair agreement between them for all strains. The MSRV methods are better than TT/TTH methods for the isolation of different strains of SE and ST in poultry fecal samples. The MSRV5 method can be used to reduce the time for the detection of SE and ST in these samples. Furthermore, a loopful of the periphery of the growth should be streaked onto differential-selective plating media, even in the absence of halo, to decrease the number of false negative results.

Prevalence of antimicrobial resistance of non-typhoidal Salmonella serovars in retail aquaculture products.

PubMed

Zhang, Jianmin; Yang, Xiaowei; Kuang, Dai; Shi, Xianming; Xiao, Wenjia; Zhang, Jing; Gu, Zhen; Xu, Xuebin; Meng, Jianghong

2015-10-01

Aquaculture products can become sources of Salmonella by exposure to contaminated water or through processing practices, thus representing a public health hazard. A study was conducted on Salmonella contamination in aquaculture products sampled from marketplaces and retailers in Shanghai, China. A total of 730 samples (including fish, shellfish, bullfrog, clam, shrimp and others) were obtained from 2006 to 2011. Among them, 217 (29.7%) were positive for Salmonella. Thirty-eight serovars were identified in the 217 Salmonella isolates. The most prevalent were Salmonella Aberdeen (18.4%), S. Wandsworth (12.0%), S. Thompson (9.2%), S. Singapore (5.5%), S. Stanley (4.6%), S. Schwarzengrund (4.6%), S. Hvittingfoss (4.1%) and S. Typhimurium (4.1%). Many resistant isolates were detected, with 69.6% resistant to at least one antimicrobial drug. We observed high resistance to sulfonamides (56.5%), tetracycline (34.1%), streptomycin (28.6%), ampicillin (23.5%) and nalidixic acid (21.2%). Lower levels of resistance were found for gentamicin (3.2%), ciprofloxacin (2.3%), ceftiofur (1.3%), cefotaxime (0.9%), ceftazidime (0.5%) and cefepime (0.5%). A total of 43.3% of the Salmonella isolates were multidrug-resistant and 44 different resistance patterns were found. This study provided data on the prevalence, serovars and antimicrobial resistance of Salmonella from retail aquaculture products in Shanghai, and indicated the need for monitoring programs for microbiologic safety in such projects and for more prudent drug use in aquaculture production in order to reduce the risk of development and spread of antimicrobial resistance. Copyright © 2015 Elsevier B.V. All rights reserved.

Oxygenated drinking water enhances immune activity in pigs and increases immune responses of pigs during Salmonella typhimurium infection.

PubMed

Jung, Bock-Gie; Lee, Jin-A; Lee, Bong-Joo

2012-12-01

It has been considered that drinking oxygenated water improves oxygen availability, which may increase vitality and improve immune functions. The present study evaluated the effects of oxygenated drinking water on immune function in pigs. Continuous drinking of oxygenated water markedly increased peripheral blood mononuclear cell proliferation, interleukin-1β expression level and the CD4(+):CD8(+) cell ratio in pigs. During Salmonella Typhimurium infection, total leukocytes and relative cytokines expression levels were significantly increased in pigs consuming oxygenated water compared with pigs consuming tap water. These findings suggest that oxygenated drinking water enhances immune activity in pigs and increases immune responses of pigs during S. Typhimurium Infection.

Activation of macrophage mediated host defense against Salmonella typhimurium by Morus alba L.

PubMed Central

Chang, BoYoon; Koo, BongSeong; Lee, HyeonCheol; Oh, Joa Sub; Kim, SungYeon

2018-01-01

Background The innate immune system plays a crucial role in the initiation and subsequent direction of adaptive immune responses, as well as in the removal of pathogens that have been targeted by an adaptive immune response. Objective Morus alba L. was reported to have immunostimulatory properties that might protect against infectious diseases. However, this possibility has not yet been explored. The present study investigated the protective and immune-enhancing ability of M. alba L. against infectious disease and the mechanisms involved. Design To investigate the immune-enhancing effects of M. alba L., we used a bacterial infection model. Results and discussions The lifespan of mice infected with a lethal dose of Salmonella typhimurium (1 × 107 colony forming units – CFU) was significantly extended when they were administered M. alba L. Furthermore, M. alba L. activated macrophages, monocytes, and neutrophils and induced Th1 cytokines (IL-12, IFN-γ, TNF-α) in mice infected with a sublethal dose (1 × 105 CFU) of S. typhimurium. M. alba L. significantly stimulated the uptake of bacteria into peritoneal macrophages as indicated by increased phagocytosis. Peritoneal macrophages derived from C3H/HeJ mice significantly inhibited M. alba L. induced NO production and TNF-α secretion compared with peritoneal macrophages derived from C3H/HeN mice. Conclusions These results suggest that the innate immune activity of M. alba L. against bacterial infection in mice occurs through activation of the TLR4 signaling pathway. PMID:29545736

Activation of macrophage mediated host defense against Salmonella typhimurium by Morus alba L.

PubMed

Chang, BoYoon; Koo, BongSeong; Lee, HyeonCheol; Oh, Joa Sub; Kim, SungYeon

2018-01-01

The innate immune system plays a crucial role in the initiation and subsequent direction of adaptive immune responses, as well as in the removal of pathogens that have been targeted by an adaptive immune response. Morus alba L. was reported to have immunostimulatory properties that might protect against infectious diseases. However, this possibility has not yet been explored. The present study investigated the protective and immune-enhancing ability of M. alba L. against infectious disease and the mechanisms involved. To investigate the immune-enhancing effects of M. alba L., we used a bacterial infection model. The lifespan of mice infected with a lethal dose of Salmonella typhimurium (1 × 10 7 colony forming units - CFU) was significantly extended when they were administered M. alba L. Furthermore, M. alba L. activated macrophages, monocytes, and neutrophils and induced Th1 cytokines (IL-12, IFN-γ, TNF-α) in mice infected with a sublethal dose (1 × 10 5 CFU) of S. typhimurium . M. alba L. significantly stimulated the uptake of bacteria into peritoneal macrophages as indicated by increased phagocytosis. Peritoneal macrophages derived from C3H/HeJ mice significantly inhibited M. alba L. induced NO production and TNF-α secretion compared with peritoneal macrophages derived from C3H/HeN mice. These results suggest that the innate immune activity of M. alba L. against bacterial infection in mice occurs through activation of the TLR4 signaling pathway.

Prevalence of ColE1-like plasmids and kanamycin resistance genes in Salmonella enterica serovars.

PubMed

Chen, Chin-Yi; Lindsey, Rebecca L; Strobaugh, Terence P; Frye, Jonathan G; Meinersmann, Richard J

2010-10-01

Multi-antimicrobial-resistant Salmonella enterica strains frequently carry resistance genes on plasmids. Recent studies focus heavily on large conjugative plasmids, and the role that small plasmids play in resistance gene transfer is largely unknown. To expand our previous studies in assessing the prevalence of the isolates harboring ColE1-like plasmids carrying the aph gene responsible for kanamycin resistance (Kan(r)) phenotypes, 102 Kan(r) Salmonella isolates collected through the National Antimicrobial Resistance Monitoring System (NARMS) in 2005 were screened by PCR using ColE1 primer sets. Thirty isolates were found to be positive for ColE1-like replicon. Plasmids from 23 isolates were able to propagate in Escherichia coli and were subjected to further characterization. Restriction mapping revealed three major plasmid groups found in three or more isolates, with each group consisting of two to three subtypes. The aph genes from the Kan(r) Salmonella isolates were amplified by PCR, sequenced, and showed four different aph(3')-I genes. The distribution of the ColE1 plasmid groups in association with the aph gene, Salmonella serovar, and isolate source demonstrated a strong linkage of the plasmid with S. enterica serovar Typhimurium DT104. Due to their high copy number and mobility, the ColE1-like plasmids may play a critical role in transmission of antibiotic resistance genes among enteric pathogens, and these findings warrant a close monitoring of this plasmid incompatibility group.

RNA-seq analysis of prophage induction in multidrug-resistant salmonella enterica serovar typhimurium DT104 following exposure to the agricultural antibiotic carbadox

USDA-ARS?s Scientific Manuscript database

Non-typhoidal Salmonella is a leading cause of U.S. foodborne disease and food-related deaths. Multidrug-resistant (MDR) Salmonella Typhimurium DT104 contains 5 prophages in the genome that may be induced to produce phage under various environmental conditions, including antibiotic exposure. We inve...

Characterization of Salmonella enterica Derivatives Harboring Defined aroC and Salmonella Pathogenicity Island 2 Type III Secretion System (ssaV) Mutations by Immunization of Healthy Volunteers

PubMed Central

Hindle, Zoë; Chatfield, Steven N.; Phillimore, Jo; Bentley, Matthew; Johnson, Julie; Cosgrove, Catherine A.; Ghaem-Maghami, Marjan; Sexton, Amy; Khan, Mohammad; Brennan, Frank R.; Everest, Paul; Wu, Tao; Pickard, Derek; Holden, David W.; Dougan, Gordon; Griffin, George E.; House, Deborah; Santangelo, Joseph D.; Khan, Shahid A.; Shea, Jaqueline E.; Feldman, Robert G.; Lewis, David J. M.

2002-01-01

The attenuation and immunogenicity of two novel Salmonella vaccine strains, Salmonella enterica serovar Typhi (Ty2 ΔaroC ΔssaV, designated ZH9) and S. enterica serovar Typhimurium (TML ΔaroC ΔssaV, designated WT05), were evaluated after their oral administration to volunteers as single escalating doses of 107, 108, or 109 CFU. ZH9 was well tolerated, not detected in blood, nor persistently excreted in stool. Six of nine volunteers elicited anti-serovar Typhi lipopolysaccharide (LPS) immunoglobulin A (IgA) antibody-secreting cell (ASC) responses, with three of three vaccinees receiving 108 and two of three receiving 109 CFU which elicited high-titer LPS-specific serum IgG. WT05 was also well tolerated with no diarrhea, although the administration of 108 and 109 CFU resulted in shedding in stools for up to 23 days. Only volunteers immunized with 109 CFU of WT05 mounted detectable serovar Typhimurium LPS-specific ASC responses and serum antibody responses were variable. These data indicate that mutations in type III secretion systems may provide a route to the development of live vaccines in humans and highlight significant differences in the potential use of serovars Typhimurium and Typhi. PMID:12065485

Horizontal Acquisition of a Multidrug-Resistance Module (R-type ASSuT) Is Responsible for the Monophasic Phenotype in a Widespread Clone of Salmonella Serovar 4,[5],12:i:.

PubMed

García, Patricia; Malorny, Burkhard; Rodicio, M Rosario; Stephan, Roger; Hächler, Herbert; Guerra, Beatriz; Lucarelli, Claudia

2016-01-01

Salmonella enterica serovar 4,[5],12:i:- is a monophasic variant of S. Typhimurium incapable of expressing the second-phase flagellar antigen (fljAB operon), and it is recognized to be one of the most prevalent serovars causing human infections. A clonal lineage characterized by phage type DT193, PulseNet PFGE profile STYMXB.0131 and multidrug resistance to ampicillin, streptomycin, sulphonamides and tetracycline (R-type ASSuT) is commonly circulating in Europe. In this study we determined the deletions affecting the fljAB operon and the resistance region responsible for the R-type ASSuT in a strain of Salmonella enterica serovar 4,5,12:i:- DT193/STYMXB.0131, through an approach based on PCRs and Southern blot hybridization of genomic DNA. Using a set of nine specific PCRs, the prevalence of the resistance region was assessed in a collection of 144 S. enterica serovar 4,[5],12:i:-/ASSuT/STYMXB.0131 strains isolated from Germany, Switzerland and Italy. A 28 kb-region is embedded between the loci STM2759 and iroB, replacing the DNA located in between, including the fljAB operon. It encompasses the genes bla TEM-1, strA-strB, sul2 and tet(B) responsible for the R-type ASSuT together with genes involved in plasmid replication and orfs of unknown function characteristically located on IncH1 plasmids. Its location and internal structure is fairly conserved in S. enterica serovar 4,[5],12:i:-/ASSuT/STYMXB.0131 strains regardless of the isolation source or country. Hence, in the S. enterica serovar 4,[5],12:i:-/ASSuT/STYMXB.0131 clonal lineage widespread in Germany, Switzerland and Italy, a resistance region derived from IncH1 plasmids has replaced the chromosomal region encoding the second flagellar phase and is an example of the stabilization of new plasmid-derived genetic material due to integration into the bacterial chromosome.

Non-Saccharomyces yeasts protect against epithelial cell barrier disruption induced by Salmonella enterica subsp. enterica serovar Typhimurium.

PubMed

Smith, I M; Baker, A; Arneborg, N; Jespersen, L

2015-11-01

The human gastrointestinal epithelium makes up the largest barrier separating the body from the external environment. Whereas invasive pathogens cause epithelial barrier disruption, probiotic micro-organisms modulate tight junction regulation and improve epithelial barrier function. In addition, probiotic strains may be able to reduce epithelial barrier disruption caused by pathogenic species. The aim of this study was to explore non-Saccharomyces yeast modulation of epithelial cell barrier function in vitro. Benchmarking against established probiotic strains, we evaluated the ability of four nonpathogenic yeast species to modulate transepithelial electrical resistance (TER) across a monolayer of differentiated human colonocytes (Caco-2 cells). Further, we assessed yeast modulation of a Salmonella Typhimurium-induced epithelial cell barrier function insult. Our findings demonstrate distinct patterns of non-Saccharomyces yeast modulation of epithelial cell barrier function. While the established probiotic yeast Saccharomyces boulardii increased TER across a Caco-2 monolayer by 30%, Kluyveromyces marxianus exhibited significantly stronger properties of TER enhancement (50% TER increase). In addition, our data demonstrate significant yeast-mediated modulation of Salmonella-induced epithelial cell barrier disruption and identify K. marxianus and Metschnikowia gruessii as two non-Saccharomyces yeasts capable of protecting human epithelial cells from pathogen invasion. This study demonstrates distinct patterns of non-Saccharomyces yeast modulation of epithelial cell barrier function in vitro. Further, our data demonstrate significant yeast-mediated modulation of Salmonella Typhimurium-induced epithelial cell barrier disruption and identify Kluyveromyces marxianus and Metschnikowia gruessii as two non-Saccharomyces yeasts capable of protecting human epithelial cells from pathogen invasion. This study is the first to demonstrate significant non-Saccharomyces yeast

Impact of relative humidity, inoculum carrier and size, and native microbiota on Salmonella ser. Typhimurium survival in baby lettuce.

PubMed

López-Gálvez, Francisco; Gil, Maria Isabel; Allende, Ana

2018-04-01

The effects of relative humidity (RH), fluctuating climate conditions, inoculum size and carrier on the survival of Salmonella enterica serovar Typhimurium on baby lettuce in environmental test chambers were studied. Buffered peptone water (BPW), distilled water (DW), and irrigation water (IW) were compared as inoculum carriers. Additionally, survival of Salmonella in suspensions prepared using filtered and unfiltered IW was assessed. Salmonella Typhimurium survived better on baby lettuce plants at high RH independently of the inoculum size. When lettuce plants were grown under fluctuating environmental conditions, Salmonella survival was similar under both RH conditions. Regarding the inoculum carrier, the inoculated microorganism survived better on lettuce plants when BPW was used as carrier both at high and low RH. Survival rate of Salmonella in IW was affected by the presence of native microbiota. Native microbiota present in IW did not affect survival of Salmonella or the levels of mesophilic bacteria on the baby lettuce leaves. The information obtained in the present study contributes to the knowledge on the effect of environmental conditions on pathogenic bacteria survival on growing edible plants. These results are useful when selecting the methodology to carry out experimental studies on the survival of microbial pathogens under different pre-harvest conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pathogenicity of Salmonella Strains Isolated from Egg Shells and the Layer Farm Environment in Australia

PubMed Central

McWhorter, Andrea R.; Davos, Dianne

2014-01-01

In Australia, the egg industry is periodically implicated during outbreaks of Salmonella food poisoning. Salmonella enterica serovar Typhimurium and other nontyphoidal Salmonella spp., in particular, are a major concern for Australian public health. Several definitive types of Salmonella Typhimurium strains, but primarily Salmonella Typhimurium definitive type 9 (DT9), have been frequently reported during egg-related food poisoning outbreaks in Australia. The aim of the present study was to generate a pathogenicity profile of nontyphoidal Salmonella isolates obtained from Australian egg farms. To achieve this, we assessed the capacity of Salmonella isolates to cause gastrointestinal disease using both in vitro and in vivo model systems. Data from in vitro experiments demonstrated that the invasion capacity of Salmonella serovars cultured to stationary phase (liquid phase) in LB medium was between 90- and 300-fold higher than bacterial suspensions in normal saline (cultured in solid phase). During the in vivo infection trial, clinical signs of infection and mortality were observed only for mice infected with either 103 or 105 CFU of S. Typhimurium DT9. No mortality was observed for mice infected with Salmonella serovars with medium or low invasive capacity in Caco-2 cells. Pathogenicity gene profiles were also generated for all serovars included in this study. The majority of serovars tested were positive for selected virulence genes. No relationship between the presence or absence of virulence genes by PCR and either in vitro invasive capacity or in vivo pathogenicity was detected. Our data expand the knowledge of strain-to-strain variation in the pathogenicity of Australian egg industry-related Salmonella spp. PMID:25362057

Effect of DSS on Bacterial Growth in Gastrointestinal Tract.

PubMed

Hlinková, J; Svobodová, H; Brachtlová, T; Gardlík, R

2016-01-01

Inflammatory bowel disease is an idiopathic autoimmune disorder that is mainly divided into ulcerative colitis and Crohn's disease. Probiotics are known for their beneficial effect and used as a treatment option in different gastrointestinal problems. The aim of our study was to find suitable bacterial vectors for gene therapy of inflammatory bowel disease. Salmonella enterica serovar Typhimurium SL7207 and Escherichia coli Nissle 1917 were investigated as potential vectors. Our results show that the growth of Escherichia coli Nissle 1917 was inhibited in the majority of samples collected from dextran sodium sulphate-treated animals compared with control growth in phosphate-buffered saline. The growth of Salmonella enterica serovar Typhimurium SL7207 in all investigated samples was enhanced or unaffected in comparison with phosphate-buffered saline; however, it did not reach the growth rates of Escherichia coli Nissle 1917. Dextran sodium sulphate treatment had a stimulating effect on the growth of both strains in homogenates of distant small intestine and proximal colon samples. The gastrointestinal tract contents and tissue homogenates did not inhibit growth of Salmonella enterica serovar Typhimurium SL7207 in comparison with the negative control, and provided more suitable environment for growth compared to Escherichia coli Nissle 1917. We therefore conclude that Salmonella enterica serovar Typhimurium SL7207 is a more suitable candidate for a potential bacterial vector, even though it has no known probiotic properties.

Novel insertion sequence- and transposon-mediated genetic rearrangements in genomic island SGI1 of Salmonella enterica serovar Kentucky.

PubMed

Doublet, Benoît; Praud, Karine; Bertrand, Sophie; Collard, Jean-Marc; Weill, François-Xavier; Cloeckaert, Axel

2008-10-01

Salmonella genomic island 1 (SGI1) is an integrative mobilizable element that harbors a multidrug resistance (MDR) gene cluster. Since its identification in epidemic Salmonella enterica serovar Typhimurium DT104 strains, variant SGI1 MDR gene clusters conferring different MDR phenotypes have been identified in several S. enterica serovars and classified as SGI1-A to -O. A study was undertaken to characterize SGI1 from serovar Kentucky strains isolated from travelers returning from Africa. Several strains tested were found to contain the partially characterized variant SGI1-K, recently described in a serovar Kentucky strain isolated in Australia. This variant contained only one cassette array, aac(3)-Id-aadA7, and an adjacent mercury resistance module. Here, the uncharacterized part of SGI1-K was sequenced. Downstream of the mer module similar to that found in Tn21, a mosaic genetic structure was found, comprising (i) part of Tn1721 containing the tetracycline resistance genes tetR and tet(A); (ii) part of Tn5393 containing the streptomycin resistance genes strAB, IS1133, and a truncated tnpR gene; and (iii) a Tn3-like region containing the tnpR gene and the beta-lactamase bla(TEM-1) gene flanked by two IS26 elements in opposite orientations. The rightmost IS26 element was shown to be inserted into the S044 open reading frame of the SGI1 backbone. This variant MDR region was named SGI1-K1 according to the previously described variant SGI1-K. Other SGI1-K MDR regions due to different IS26 locations, inversion, and partial deletions were characterized and named SGI1-K2 to -K5. Two new SGI1 variants named SGI1-P1 and -P2 contained only the Tn3-like region comprising the beta-lactamase bla(TEM-1) gene flanked by the two IS26 elements inserted into the SGI1 backbone. Three other new variants harbored only one IS26 element inserted in place of the MDR region of SGI1 and were named SGI1-Q1 to -Q3. Thus, in serovar Kentucky, the SGI1 MDR region undergoes recombinational and

Influence of Natural Organic Matter on Attachment Kinetics of Salmonella Typhimurium

NASA Astrophysics Data System (ADS)

Chowdhury, I.; Zorlu, O.; Hill, J. E.; Walker, S. L.

2011-12-01

Salmonella enterica serovar Typhimurium is one of the most common and virulent bacterial pathogens, usually found in food and water. This waterborne pathogen has been attributed to causing gastroenteritis and typhoid fever, leading to 16 million cases and over half a million deaths worldwide each year. Natural organic matter (NOM) is ubiquitous in environment and previous work has shown NOM to enhance the stability and transport of bacteria cells; hence NOM will certainly interact with Salmonella and affect its transport in environment. The objective of this study was to investigate the influence of NOM (Suwannee River humic acid standard II, SRHA) on the attachment kinetics of a model Salmonella (Salmonella enterica serovar Typhimurium SA5983) to glass. The transport study was conducted in a parallel plate flow chamber using fluorescent microscope to visualize the bacterial cells, which were tagged with green fluorescent protein (GFP). The solution pH was unadjusted, and the flow rate through parallel plate channel was 0.1 mL/min to simulate groundwater conditions. Parameters varied in this study were NOM presence, ion valence (K+, Ca2+) as well as cell growth phase (mid-exponential and late-exponential growth phases). These parameters were chosen because ion valence may alter the NOM conformation and capacity for bridging, as well growth phase impacts the cellular surface chemistry. Extensive characterization of the bacterial cells was conducted including measurements of electrophoretic mobility, hydrophobicity, acidity, surface charge density and extracellular polymeric substance content. Additionally, electrokintic characterization was conducted for the glass. Preliminary results demonstrated the sensitivity of cell attachment to ionic valence and cell growth phase. Also the addition of NOM reduced the attachment of the Salmonella cells significantly under all of these conditions. Without NOM, attachment efficiencies (α) in KCl were similar at both growth

Prevalence of ColE1-Like Plasmids and Kanamycin Resistance Genes in Salmonella enterica Serovars ▿

PubMed Central

Chen, Chin-Yi; Lindsey, Rebecca L.; Strobaugh, Terence P.; Frye, Jonathan G.; Meinersmann, Richard J.

2010-01-01

Multi-antimicrobial-resistant Salmonella enterica strains frequently carry resistance genes on plasmids. Recent studies focus heavily on large conjugative plasmids, and the role that small plasmids play in resistance gene transfer is largely unknown. To expand our previous studies in assessing the prevalence of the isolates harboring ColE1-like plasmids carrying the aph gene responsible for kanamycin resistance (Kanr) phenotypes, 102 Kanr Salmonella isolates collected through the National Antimicrobial Resistance Monitoring System (NARMS) in 2005 were screened by PCR using ColE1 primer sets. Thirty isolates were found to be positive for ColE1-like replicon. Plasmids from 23 isolates were able to propagate in Escherichia coli and were subjected to further characterization. Restriction mapping revealed three major plasmid groups found in three or more isolates, with each group consisting of two to three subtypes. The aph genes from the Kanr Salmonella isolates were amplified by PCR, sequenced, and showed four different aph(3′)-I genes. The distribution of the ColE1 plasmid groups in association with the aph gene, Salmonella serovar, and isolate source demonstrated a strong linkage of the plasmid with S. enterica serovar Typhimurium DT104. Due to their high copy number and mobility, the ColE1-like plasmids may play a critical role in transmission of antibiotic resistance genes among enteric pathogens, and these findings warrant a close monitoring of this plasmid incompatibility group. PMID:20693446

Detoxification of Salmonella typhimurium lipopolysaccharide by ionizing radiation.

PubMed

Previte, J J; Chang, Y; el-Bisi, H M

1967-05-01

The efficiency of ionizing radiation in detoxifying the lethal determinant(s) of the lipopolysaccharide (LPS) of Salmonella typhimurium, S. enteritidis, and Escherichia coli in aqueous solution and associated with heat-killed S. typhimurium cells in suspension decreased with doses above 1 Mrad. The 50% end point of inactivation was more than 7.0 Mrad for heat-killed salmonellae and 4.8, 4.5, and 1.0 Mrad for the LPS of S. typhimurium, S. enteritidis, and E. coli, respectively. After exposure to 20 Mrad, S. typhimurium LPS retained a small portion of its lethal properties although the ld(50) was much greater than 9.5 mg per 20-g mouse. However, at -184 C, no inactivation of the lethal determinant(s) occurred after exposure to as much as 20 Mrad. This demonstrated the significance of the indirect effect and the mobility and formation of free radicals. At 22 C, the optical density at 400 mmu increased and the pH decreased with increasing radiation dose, but no qualitative changes were observed in the infrared spectrum. No change was observed in the pyrogenicity of S. typhimurium LPS; a slight decrease in antigenicity was revealed when 6 days, but not when 1 day, elapsed between vaccination and challenge in the mouse protection test. The results were interpreted as evidence of the existence of two or more lethal and antigenic determinants. The differential effect of radiation on these properties and on the pyrogenic component(s) probably are indicative of separate functional sites for lethal, antigenic, and pyrogenic activities.

High Phenotypic Variability among Representative Strains of Common Salmonella enterica Serovars with Possible Implications for Food Safety.

PubMed

Abdullah, Wan Zawiah Wan; Mackey, Bernard M; Karatzas, Kimon Andreas G

2018-01-01

Salmonella is an important foodborne pathogen, whose ability to resist stress and survive can vary among strains. This variability is normally not taken into account when predictions are made about survival in foods with negative consequences. Therefore, we examined the contribution of variable phenotypic properties to survival under stress in 10 Salmonella serovars. One strain (Typhimurium 10) was intentionally RpoS-negative; however, another strain (Heidelberg) showed an rpoS mutation, rendering it inactive. We assessed an array of characteristics (motility, biofilm formation, bile resistance, acid resistance, and colony morphology) that show major variability among strains associated with a 10- to 19-fold difference between the highest and the lowest strain for most characteristics. The RpoS status of isolates did not affect variability in the characteristics, with the exception of resistance to NaCl, acetic acid, lactic acid, and the combination of acetic acid and salt, where the variability between the highest and the lowest strain was reduced to 3.1-fold, 1.7-fold, 2-fold, and 1.7-fold, respectively, showing that variability was significant among RpoS-positive strains. Furthermore, we also found a good correlation between acid resistance and lysine decarboxylase activity, showing its importance for acid resistance, and demonstrated a possible role of RpoS in the lysine decarboxylase activity in Salmonella.

MALDI-TOF mass spectrometry provides high accuracy in identification of Salmonella at species level but is limited to type or subtype Salmonella serovars.

PubMed

Kang, Lin; Li, Nan; Li, Ping; Zhou, Yang; Gao, Shan; Gao, Hongwei; Xin, Wenwen; Wang, Jinglin

2017-04-01

Salmonella can cause global foodborne illnesses in humans and many animals. The current diagnostic gold standard used for detecting Salmonella infection is microbiological culture followed by serological confirmation tests. However, these methods are complicated and time-consuming. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis offers some advantages in rapid identification, for example, simple and fast sample preparation, fast and automated measurement, and robust and reliable identification up to genus and species levels, possibly even to the strain level. In this study, we established a reference database for species identification using whole-cell MALDI-TOF MS; the database consisted of 12 obtained main spectra of the Salmonella culture collection strains belonged to seven serotypes. Eighty-two clinical isolates of Salmonella were identified using established database, and partial 16S rDNA gene sequencing and serological method were used as comparison. We found that MALDI-TOF mass spectrometry provided high accuracy in identification of Salmonella at species level but was limited to type or subtype Salmonella serovars. We also tried to find serovar-specific biomarkers and failed. Our study demonstrated that (a) MALDI-TOF MS was suitable for identification of Salmonella at species level with high accuracy and (b) that MALDI-TOF MS method presented in this study was not useful for serovar assignment of Salmonella currently, because of its low matching with serological method and (c) MALDI-TOF MS method presented in this study was not suitable to subtype S. typhimurium because of its low discriminatory ability.

Green synthesized nickel nanoparticles for targeted detection and killing of S. typhimurium.

PubMed

Jeyaraj Pandian, Chitra; Palanivel, Rameshthangam; Balasundaram, Usha

2017-09-01

Simple and sensitive colorimetric immunosensor based on peroxidase mimetic activity and photothermal effect of nickel oxide nanoparticle (NiOGs) has been developed to detect and kill food borne pathogen Salmonella typhimurium. NiOGs showed superior peroxidase mimetic activity for oxidation of peroxidase substrate 3, 3', 5, 5'-tetramethylbenzidine (TMB). Oxidation of TMB by NiOGs followed Michaelis-Menten kinetics with K m and V max values of 0.25mM and 2.64×10 -8 M/s respectively. NiOGs was coated with citric acid (CA-NiOGs) followed by conjugation with antibody (anti-S. typhimurium) (Ab-CA-NiOGs) that effectively captured S. typhimurium. Colorimetric detection of S. typhimurium by Ab-CA-NiOGs showed a linear relationship between pathogen concentration (1×10 1 to 1×10 6 cfu/mL) and color signal (652nm) with limit of detection (LOD) of 10cfu/mL. The proposed method showed no cross reactivity against other pathogens. Recovery of S. typhimurium in milk and juice samples was found to be 95 to 100% and 92 to 99% respectively. NiOGs exposed to laser irradiation showed dose dependent increase in temperature and singlet oxygen within 5min. Bacteria bound to Ab-CA-NiOGs after laser irradiation, induced membrane damage and reduced bacterial viability to 6%. The bifunctional peroxidase-mimetic activity and photothermal effect of NiOGs can be exploited in selective sensing and killing of target pathogens respectively in food products. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular differentiation between Salmonella enterica subsp enterica serovar Pullorum and Salmonella enterica subsp enterica serovar Gallinarum

PubMed Central

Ribeiro, Simone Alves Mendes; de Paiva, Jaqueline Boldrin; Zotesso, Fábio; Lemos, Manoel Victor Franco; Berchieri Jánior, Ângelo

2009-01-01

S. Pullorum (SP) and S. Gallinarum (SG) are very similar. They are the agents of pullorum disease and fowl typhoid, respectively, and the two diseases are responsible for economic losses in poultry production. Although SP and SG are difficult to be differentiated in routine laboratory procedures, the ability to metabolize ornithine is a biochemical test that may be used to achieve this aim. While SP is able to decarboxylate this amino acid, SG is not. However, the isolation of strains showing atypical biochemical behavior has made this differentiation difficult. One of the genes associated with the metabolization of the amino acid ornithine is called speC, and is found in both serovars. The analysis of 21 SP and 15 SG strains by means of PCR did not enable the differentiation of the two serovars, because fragments produced were identical. However, after enzymatic treatment with restriction enzyme Eco RI, the band pattern of each serovar showed to be different, even in samples of atypical biochemical behavior. This fact enabled the standardization of the technique for a quick and safe differentiation of serovars Pullorum and Gallinarum. PMID:24031341

Longitudinal Study of Distributions of Similar Antimicrobial-Resistant Salmonella Serovars in Pigs and Their Environment in Two Distinct Swine Production Systems

PubMed Central

Keelara, Shivaramu; Scott, H. Morgan; Morrow, William M.; Gebreyes, Wondwossen A.; Correa, Maria; Nayak, Rajesh; Stefanova, Rossina

2013-01-01

The aim of this longitudinal study was to determine and compare the prevalences and genotypic profiles of antimicrobial-resistant (AR) Salmonella isolates from pigs reared in antimicrobial-free (ABF) and conventional production systems at farm, at slaughter, and in their environment. We collected 2,889 pig fecal and 2,122 environmental (feed, water, soil, lagoon, truck, and floor swabs) samples from 10 conventional and eight ABF longitudinal cohorts at different stages of production (farrowing, nursery, finishing) and slaughter (postevisceration, postchill, and mesenteric lymph nodes [MLN]). In addition, we collected 1,363 carcass swabs and 205 lairage and truck samples at slaughter. A total of 1,090 Salmonella isolates were recovered from the samples; these were isolated with a significantly higher prevalence in conventionally reared pigs (4.0%; n = 66) and their environment (11.7%; n = 156) than in ABF pigs (0.2%; n = 2) and their environment (0.6%; n = 5) (P < 0.001). Salmonella was isolated from all stages at slaughter, including the postchill step, in the two production systems. Salmonella prevalence was significantly higher in MLN extracted from conventional carcasses than those extracted from ABF carcasses (P < 0.001). We identified a total of 24 different serotypes, with Salmonella enterica serovar Typhimurium, Salmonella enterica serovar Anatum, Salmonella enterica serovar Infantis, and Salmonella enterica serovar Derby being predominant. The highest frequencies of antimicrobial resistance (AR) were exhibited to tetracycline (71%), sulfisoxazole (42%), and streptomycin (17%). Multidrug resistance (resistance to ≥3 antimicrobials; MDR) was detected in 27% (n = 254) of the Salmonella isolates from the conventional system. Our study reports a low prevalence of Salmonella in both production systems in pigs on farms, while a higher prevalence was detected among the carcasses at slaughter. The dynamics of Salmonella prevalence in pigs and carcasses were

Long-Term Survival Phase Cells of Salmonella Typhimurium ATCC 14028 Have Significantly Greater Resistance to Ultraviolet Radiation in 0.85% Saline and Apple Juice.

PubMed

Wang, Fei; Mendonça, Aubrey; Brehm-Stecher, Byron F; Dickson, James; DiSpirito, Alan; Shaw, Angela; Thomas-Popo, Emalie

2018-05-31

Nonendospore-forming pathogenic bacteria in the long-term survival (LTS) phase can remain viable for months or years and may show reduced susceptibility to various antimicrobial interventions. In the present study, we investigated the response of LTS phase Salmonella enterica serovar Typhimurium (ATCC 14028) to ultraviolet (UV) radiation in 0.85% (w/v) saline and apple juice and the extent of sublethal injury in LTS phase survivors. The LTS-phase Salmonella Typhimurium cells were cultured at 35°C for 14 days in tryptic soy broth with 0.6% (w/v) yeast extract (TSBYE). Exponential- and stationary-phase cells, cultured in TSBYE (35°C) for 2.5 and 18 h, respectively, served as control samples. Cells (10 7 CFU [colony-forming unit]/mL) from each physiological state were exposed to UV light in saline (80 μW/cm 2 ) and apple juice (1500 μW/cm 2 ). The Salmonella Typhimurium survivors were plated for enumeration on either tryptic soy agar with 0.6% yeast extract or xylose-lysine-tergitol 4 (XLT4) agar and colonies counted after incubation (35°C, 24 h). Of all the growth phases tested, LTS phase cells were consistently impacted the least by UV treatment (p < 0.05). In saline, D-values of exponential, stationary, and LTS Salmonella Typhimurium were 0.35, 0.38, and 0.49 min, respectively. D-values in apple juice at pH 3.63 and pH 5.65 were 2.52, 3.19, and 3.57 min and 3.24, 3.50, and 4.18 min, respectively. UV radiation (80 μW/cm 2 ) of Salmonella Typhimurium in saline for 2.5 min reduced the number of exponential- and stationary-phase cells by ∼7.19 and 6.30 log 10 CFU/mL, respectively. In contrast, LTS cells were only reduced by 5.08 log 10 CFU/mL. Among the three physiological states, LTS phase cells had the least sublethal injury in the surviving population (p < 0.05). These results indicate that the LTS state cross-protects Salmonella Typhimurium against UV radiation and should be considered in determination of the UV radiation D

Lactobacillus paracasei metabolism of rice bran reveals metabolome associated with Salmonella Typhimurium growth reduction.

PubMed

Nealon, N J; Worcester, C R; Ryan, E P

2017-06-01

This study aimed to determine the effect of a cell-free supernatant of Lactobacillus paracasei ATCC 27092 with and without rice bran extract (RBE) on Salmonella Typhimurium 14028s growth, and to identify a metabolite profile with antimicrobial functions. Supernatant was collected from overnight cultures of L. paracasei incubated in the presence (LP+RBE) or absence (LP) of RBE and applied to S. Typhimurium. LP+RBE reduced 13·1% more S. Typhimurium growth than LP after 16 h (P < 0·05). Metabolite profiles of LP and LP+RBE were examined using nontargeted global metabolomics consisting of ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. A comparison of LP and LP+RBE revealed 84 statistically significant metabolites (P < 0·05), where 20 were classified with antimicrobial functions. LP+RBE reduced S. Typhimurium growth to a greater extent than LP, and the metabolite profile distinctions suggested that RBE favourably modulates the metabolism of L. paracasei. These findings warrant continued investigation of probiotic and RBE antimicrobial activities across microenvironments and matrices where S. Typhimurium exposure is problematic. This study showed a novel metabolite profile of probiotic L. paracasei and prebiotic rice bran that increased antimicrobial activity against S. Typhimurium. © 2017 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of The Society for Applied Microbiology.

Dr. Cheryl Nickerson studies Salmonella Typhimurium

NASA Technical Reports Server (NTRS)

2003-01-01

Dr. Cheryl Nickerson of Tulane University is studying the effects of simulated low-g on a well-known pathogen, Salmonella typhimurium, a bacterium that causes two to four million cases of gastrointestinal illness in the United States each year. While most healthy people recover readily, S. typhimurium can kill people with weakened immune systems. Thus, a simple case of food poisoning could disrupt a space mission. Using the NASA rotating-wall bioreactor, Nickerson cultured S. typhimurium in modeled microgravity. Mice infected with the bacterium died an average of three days faster than the control mice, indicating that S. typhimurium's virulence was enhanced by the bioreactor. Earlier research showed that 3 percent of the genes were altered by exposure to the bioreactor. Nickerson's work earned her a 2001 Presidential Early Career Award for Scientists and Engineers.

Coordinated Regulation of Virulence during Systemic Infection of Salmonella enterica serovar Typhimurium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Hyunjin; McDermott, Jason E.; Porwollik, Steffen

Salmonella must respond to a myriad of environmental cues during infection of a mouse and express specific subsets of genes in a temporal and spatial manner to subvert the host defense mechanisms but these regulatory pathways are poorly established. To unravel how micro-environmental signals are processed and integrated into coordinated action, we constructed in-frame non-polar deletions of 84 regulators inferred to play a role in Salmonella typhimurium virulence and tested them in three virulence assays (intraperitoneal (i.p.), and intragastric (i.g.) infection in BALB/c mice, and persistence in SvJ129 mice). Overall 36 regulators were identified that were less virulent in atmore » least one assay, and of those, 15 regulators were required for systemic mouse infection in an acute infection model. As a first step towards understanding the interplay between a pathogen and its host from a systems biology standpoint we focused on these 15 genes. Transcriptional profiles were obtained for each of these 15 regulators from strains grown under four different environmental conditions. These results as well as publicly available transcriptional profiles were analyzed using both network inference and cluster analysis algorithms. The analysis predicts a regulatory network in which all 15 regulators control a specific set of genes necessary for Salmonella to cause systemic infection. We tested the regulatory model by expressing a subset of the regulators in trans and monitoring transcription of 7 known virulence factors located within Salmonella pathogenicity island 2 (SPI-2). These experiments validated the regulatory model and showed that, for these 7 genes, the response regulator SsrB and the marR type regulator SlyA co-regulate in a regulatory cascade by integrating multiple signals.« less

In vitro studies of chicken egg yolk antibody (IgY) against Salmonella enteritidis and Salmonella typhimurium.

PubMed

Lee, E N; Sunwoo, H H; Menninen, K; Sim, J S

2002-05-01

Chicken egg yolk antibody (IgY) raised against Salmonella enteritidis or Salmonella typhimurium was found in highly specific activity levels by ELISA. S. enteritidis- and S. typhimurium-specific IgY powder, prepared by freeze-drying the egg yolk water-soluble fraction, contained 15.5 and 10.0% of specific IgY, respectively. Anti-S. enteritidis IgY cross-reacted 55.3% with S. typhimurium. The cross-reactivity of anti-S. typhimurium IgY with S. enteritidis was 42.4%. Salmonella-specific IgY was demonstrated to inhibit Salmonella growth in liquid medium. The growth rate of S. enteritidis incubated with S. enteritidis-specific IgY was fourfold less than that of the control group during a 4-to-6-h incubation. Cell counts of S. typhimurium incubated with S. typhimurium-specific IgY were reduced by 1.6 log cfu/mL in comparison to that of the control group after 6 h of incubation. The specific binding activity of IgY was further evaluated by using immunofluorescence and immunoelectron microscopy. It was found that Salmonella-specific IgY could bind to the antigens expressed on the Salmonella surface, resulting in structural alterations of the bacterial surface.

Ureaplasma serovars & their antimicrobial susceptibility in patients of infertility & genital tract infections.

PubMed

Dhawan, Benu; Malhotra, Neena; Sreenivas, Vishnubhatla; Rawre, Jyoti; Khanna, Neena; Chaudhry, Rama; Mittal, Suneeta

2012-12-01

Ureaplasmas have been implicated in a variety of clinical conditions. However, only certain serovars of ureaplasmas are disease associated. Only a few classes of antimicrobial agents are available for the treatment of mycoplasmal infections in humans. Increase of resistance of genital mycoplasmas to antimicrobials has been reported worldwide. The aim of the present study was to determine the occurrence of Ureaplasma serovars in patients with infertility and genital tract infections with polymerase chain reaction (PCR)-based serotyping. The antimicrobial susceptibilities of Ureaplasma spp. and Mycoplasma hominis were also assessed to determine the most suitable treatment strategy. Sexually active adults (n=147) with symptoms of genital tract infections and 115 infertile women were enrolled. Endocervical swabs from women and urethral swabs from men were subjected to culture and multiplex PCR for detection of genital mycoplasmas. Serotyping of Ureaplasma was done by PCR and antimicrobial susceptibility to doxycycline, azithromycin, josamycin and ofloxacin was done by microbroth dilution method. Ureaplasma was detected in 25.8 per cent patients with genital tract infections and 20.8 per cent in infertile women. Serovar 3/14 was the most frequent isolate followed by serovar 1 and serovar 6. The majority of Ureaplasma isolates were susceptible to doxycycline (91%) and josamycin (86%) followed by ofloxacin (77%) and azithromycin (71%). All the isolates of M. hominis were uniformly susceptible to doxycycline, josamycin and ofloxacin. The predominance of Ureaplasma serovar 3/14 suggests their possible pathogenic role in genital tract infections and infertility. For empirical treatment, doxycycline could be the drug of choice for genital mycoplasmas.

Genetic Separation of Hypoxanthine and Guanine-Xanthine Phosphoribosyltransferase Activities by Deletion Mutations in Salmonella typhimurium

PubMed Central

Gots, Joseph S.; Benson, Charles E.; Shumas, Susan R.

1972-01-01

Certain proAB deletion mutants of Salmonella typhimurium were found to be simultaneously deleted in a gene required for the utilization of guanine and xanthine (designated gxu). These mutants were resistant to 8-azaguanine and when carrying an additional pur mutation were unable to use guanine or xanthine as a purine source. The defect was correlated with deficiencies in the uptake and phosphoribosyltransferase activities for guanine and xanthine. Hypoxanthine and adenine activities were unaltered. The deficiency was restored to normal by transduction to pro+ and in F′ merodiploids. PMID:4563984

Counts, serovars, and antimicrobial resistance phenotypes of Salmonella on raw chicken meat at retail in Colombia.

PubMed

Donado-Godoy, Pilar; Clavijo, Viviana; León, Maribel; Arevalo, Alejandra; Castellanos, Ricardo; Bernal, Johan; Tafur, Mc Allister; Ovalle, Maria Victoria; Alali, Walid Q; Hume, Michael; Romero-Zuñiga, Juan Jose; Walls, Isabel; Doyle, Michael P

2014-02-01

The objective of this study was to determine Salmonella counts, serovars, and antimicrobial-resistant phenotypes on retail raw chicken carcasses in Colombia. A total of 301 chicken carcasses were collected from six departments (one city per department) in Colombia. Samples were analyzed for Salmonella counts using the most-probable-number method as recommended by the U.S. Department of Agriculture, Food Safety Inspection Service protocol. A total of 378 isolates (268 from our previous study) were serotyped and tested for antimicrobial susceptibility. The overall Salmonella count (mean log most probable number per carcass ± 95% confidence interval) and prevalence were 2.1 (2.0 to 2.3) and 37%, respectively. There were significant differences (P < 0.05) by Salmonella levels (i.e., counts and prevalence) by storage temperature (i.e., frozen, chilled, or ambient), retail store type (wet markets, supermarkets, and independent markets), and poultry company (chicken produced by integrated or nonintegrated company). Frozen chicken had the lowest Salmonella levels compared with chicken stored at other temperatures, chickens from wet markets had higher levels than those from other retail store types, and chicken produced by integrated companies had lower levels than nonintegrated companies. Thirty-one Salmonella serovars were identified among 378 isolates, with Salmonella Paratyphi B tartrate-positive (i.e., Salmonella Paratyphi B dT+) the most prevalent (44.7%), followed by Heidelberg (19%), Enteritidis (17.7%), Typhimurium (5.3%), and Anatum (2.1%). Of all the Salmonella isolates, 35.2% were resistant to 1 to 5 antimicrobial agents, 24.6% to 6 to 10, and 33.9% to 11 to 15. Among all the serovars obtained, Salmonella Paratyphi B dT+ and Salmonella Heidelberg were the most antimicrobial resistant. Salmonella prevalence was determined to be high, whereas cell numbers were relatively low. These data can be used in developing risk assessment models for preventing the

Effect of Electropermeabilization by Ohmic Heating for Inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Buffered Peptone Water and Apple Juice

PubMed Central

Park, Il-Kyu

2013-01-01

The effect of electric field-induced ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P < 0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (P < 0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating. PMID:23995939

Effect of electropermeabilization by ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in buffered peptone water and apple juice.

PubMed

Park, Il-Kyu; Kang, Dong-Hyun

2013-12-01

The effect of electric field-induced ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P<0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (P<0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating.

Effect of Water Activity on the Thermal Tolerance and Survival of Salmonella enterica Serovars Tennessee and Senftenberg in Goat's Milk Caramel.

PubMed

Acosta, Oscar; Usaga, Jessie; Churey, John J; Worobo, Randy W; Padilla-Zakour, Olga I

2017-06-01

The low thermal tolerance of Salmonella enterica in foods with intermediate moisture levels, such as caramel sauces, ensures that mild heat treatment is sufficient to achieve 5-log reductions of this pathogen. This treatment mitigates the risk posed by salmonellae in raw materials; however, recontamination might occur because of survival of the pathogen in products that are not heated before consumption. This study was conducted to evaluate the effect of water activity (a w ) on the thermal tolerance and survival of S. enterica serovars Tennessee and Senftenberg. The D-values at 76, 78, and 80°C, z-values, and survival at 20.0 ± 0.5°C for 32 weeks of these two serovars were determined in goat's milk caramel at three a w values (0.85, 0.90, and 0.93). The highest thermal tolerance was observed at a w = 0.85 for Salmonella Senftenberg (D 76°C = 2.9 ± 0.3 min), and the lowest was at a w = 0.93 for Salmonella Tennessee (D 80°C = 0.131 ± 0.007 min). After a logarithmic transformation of the z-values, a significant interaction between serovar and a w was found (P < 0.0001), but no consistent trends were observed at the three evaluated a w levels for either serovar. Survival response was modeled using two sigmoidal three-parameter models. A significant interaction was found between nominal variables a w and serovar when comparing inflection points of the resulting curves: P < 0.0016 for the logistic model (R 2 = 0.91) and P < 0.0014 for the Gompertz model (R 2 = 0.92). Although a >8-log reduction was observed at week 20 of storage, regardless of the product's a w and the serovar, low levels of salmonellae were found in the product up to week 32 of storage. Our findings may assist the food industry with the establishment of critical limits for the safe thermal treatment of milk- and sugar-based foods with intermediate moisture levels. The survival data presented here highlight the relevance of implementing and effectively maintaining good sanitation and hygiene

Development of two real-time polymerase chain reaction assays to detect Actinobacillus pleuropneumoniae serovars 1-9-11 and serovar 2.

PubMed

Marois-Créhan, Corinne; Lacouture, Sonia; Jacques, Mario; Fittipaldi, Nahuel; Kobisch, Marylène; Gottschalk, Marcelo

2014-01-01

Two real-time, or quantitative, polymerase chain reaction (qPCR) assays were developed to detect Actinobacillus pleuropneumoniae serovars 1-9-11 (highly related serovars with similar virulence potential) and serovar 2, respectively. The specificity of these assays was verified on a collection of 294 strains, which included all 16 reference A. pleuropneumoniae strains (including serovars 5a and 5b), 263 A. pleuropneumoniae field strains isolated between 1992 and 2009 in different countries, and 15 bacterial strains other than A. pleuropneumoniae. The detection levels of both qPCR tests were evaluated using 10-fold dilutions of chromosomal DNA from reference strains of A. pleuropneumoniae serovars 1 and 2, and the detection limit for both assays was 50 fg per assay. The analytical sensitivities of the qPCR tests were also estimated by using pure cultures and tonsils experimentally spiked with A. pleuropneumoniae. The detection threshold was 2.5 × 10(4) colony forming units (CFU)/ml and 2.9 × 10(5) CFU/0.1 g of tonsil, respectively, for both assays. These specific and sensitive tests can be used for the serotyping of A. pleuropneumoniae in diagnostic laboratories to control porcine pleuropneumonia.

Salmonellosis

USGS Publications Warehouse

Friend, Milton

1999-01-01

Avian salmonellosis is caused by a group of bacteria of the genus salmonella. Approximately 2,300 different strains of salmonellae have been identified, and these are placed into groupings called “serovars” on the basis of their antigens or substances that induce immune response by the host, such as the production of specific antibody to the antigen. Current taxonomic nomenclature considers the 2,300 different serovars to be variants of two species, Salmonella enterica and S. bongori. S. enterica is further subdivided into six subspecies on the basis of biochemical characteristics. This results in complex nomenclature for each serovar, such as, S. enterica subsp. enterica serovar typhimurium. Readers should be aware of this convention for naming salmonellae because they will find this nomenclature in the current scientific literature. In this chapter, different serovars of salmonellae will be referred to by their previous, less complex nomenclature, such as S. typhimurium.

Isolation and purification of enterocin E-760 with broad antimicrobial activity against gram-positive and gram-negative bacteria.

PubMed

Line, J E; Svetoch, E A; Eruslanov, B V; Perelygin, V V; Mitsevich, E V; Mitsevich, I P; Levchuk, V P; Svetoch, O E; Seal, B S; Siragusa, G R; Stern, N J

2008-03-01

Strain NRRL B-30745, isolated from chicken ceca and identified as Enterococcus durans, Enterococcus faecium, or Enterococcus hirae, was initially identified as antagonistic to Campylobacter jejuni. The isolate produced a 5,362-Da bacteriocin (enterocin) that inhibits the growth of Salmonella enterica serovar Enteritidis, S. enterica serovar Choleraesuis, S. enterica serovar Typhimurium, S. enterica serovar Gallinarum, Escherichia coli O157:H7, Yersinia enterocolitica, Citrobacter freundii, Klebsiella pneumoniae, Shigella dysenteriae, Pseudomonas aeruginosa, Proteus mirabilis, Morganella morganii, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Campylobacter jejuni, and 20 other Campylobacter species isolates. The enterocin, E-760, was isolated and purified by cation-exchange and hydrophobic-interaction chromatographies. The proteinaceous nature of purified enterocin E-760 was demonstrated upon treatment with various proteolytic enzymes. Specifically, the antimicrobial peptide was found to be sensitive to beta-chymotrypsin, proteinase K, and papain, while it was resistant to lysozyme and lipase. The enterocin demonstrated thermostability by retaining activity after 5 min at 100 degrees C and was stable at pH values between 5.0 and 8.7. However, activity was lost below pH 3.0 and above pH 9.5. Administration of enterocin E-760-treated feed significantly (P < 0.05) reduced the colonization of young broiler chicks experimentally challenged and colonized with two strains of C. jejuni by more than 8 log(10) CFU. Enterocin E-760 also significantly (P < 0.05) reduced the colonization of naturally acquired Campylobacter species in market age broiler chickens when administered in treated feed 4 days prior to analysis.

Multidrug-resistant Salmonella Typhimurium in Four Animal Facilities

PubMed Central

Wright, Jennifer G.; Tengelsen, Leslie A.; Smith, Kirk E.; Bender, Jeff B.; Frank, Rodney K.; Grendon, John H.; Rice, Daniel H.; Thiessen, Ann Marie B.; Gilbertson, Catherine Jo; Sivapalasingam, Sumathi; Barrett, Timothy J.; Besser, Thomas E.; Hancock, Dale D.

2005-01-01

In 1999 and 2000, 3 state health departments reported 4 outbreaks of gastrointestinal illness due to Salmonella enterica serotype Typhimurium in employees, clients, and client animals from 3 companion animal veterinary clinics and 1 animal shelter. More than 45 persons and companion animals became ill. Four independent investigations resulted in the testing of 19 human samples and >200 animal samples; 18 persons and 36 animals were culture-positive for S. Typhimurium. One outbreak was due to multidrug-resistant S. Typhimurium R-type ACKSSuT, while the other 3 were due to multidrug-resistant S. Typhimurium R-type ACSSuT DT104. This report documents nosocomial transmission of S. Typhimurium and demonstrates that companion animal facilities may serve as foci of transmission for salmonellae between animals and humans if adequate precautions are not followed. PMID:16102313

Methods for Tumor Targeting with Salmonella typhimurium A1-R.

PubMed

Hoffman, Robert M; Zhao, Ming

2016-01-01

Salmonella typhimurium A1-R (S. typhimurium A1-R) has shown great preclinical promise as a broad-based anti-cancer therapeutic (please see Chapter 1 ). The present chapter describes materials and methods for the preclinical study of S. typhimurium A1-R in clinically-relevant mouse models. Establishment of orthotopic metastatic mouse models of the major cancer types is described, as well as other useful models, for efficacy studies of S. typhimurium A1-R or other tumor-targeting bacteria, as well. Imaging methods are described to visualize GFP-labeled S. typhimurium A1-R, as well as GFP- and/or RFP-labeled cancer cells in vitro and in vivo, which S. typhimurium A1-R targets. The mouse models include metastasis to major organs that are life-threatening to cancer patients including the liver, lung, bone, and brain and how to target these metastases with S. typhimurium A1-R. Various routes of administration of S. typhimurium A1-R are described with the advantages and disadvantages of each. Basic experiments to determine toxic effects of S. typhimurium A1-R are also described. Also described are methodologies for combining S. typhimurium A1-R and chemotherapy. The testing of S. typhimurium A1-R on patient tumors in patient-derived orthotopic xenograft (PDOX) mouse models is also described. The major methodologies described in this chapter should be translatable for clinical studies.

Aptasensors for quantitative detection of Salmonella Typhimurium.

PubMed

Ansari, Najmeh; Yazdian-Robati, Rezvan; Shahdordizadeh, Mahin; Wang, Zhouping; Ghazvini, Kiarash

2017-09-15

Salmonella is one of the most frequent causes of food borne infectious disease. Among nearly 2500 documented serotypes are reported, Salmonella Typhimurium is the number one serotype associated with salmonellosis worldwide. Many different methods have been developed for the detection and quantification of S. typhimurium. Most of these assays are usually expensive, time consuming and require difficult sample preparation steps. Therefore, it is necessary to develop rapid, robust, cost-effective and sensitive alternative detection methods. In the last years, aptasensors, used for detection of S. typhimurium in different samples. In this review, recent advances and applications of aptasensors for the detection and quantification of S. typhimurium in details have been summarized. Copyright © 2017 Elsevier Inc. All rights reserved.

Multidrug-resistant Salmonella enterica serovar Infantis, Israel.

PubMed

Gal-Mor, Ohad; Valinsky, Lea; Weinberger, Miriam; Guy, Sara; Jaffe, Joseph; Schorr, Yosef Ilan; Raisfeld, Abraham; Agmon, Vered; Nissan, Israel

2010-11-01

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.

Outer membrane vesicles from flagellin-deficient Salmonella enterica serovar Typhimurium induce cross-reactive immunity and provide cross-protection against heterologous Salmonella challenge.

PubMed

Liu, Qiong; Liu, Qing; Yi, Jie; Liang, Kang; Hu, Bo; Zhang, Xiangmin; Curtiss, Roy; Kong, Qingke

2016-10-04

Outer membrane vesicles (OMVs) isolated from Salmonella Typhimurium are potentially useful for developing subunit vaccines because of high immunogenicity and protective efficacy. However, flagella might remain in OMV pellets following OMV purification, resulting in non-essential immune responses and counteraction of bacterial protective immune responses when developing a vaccine against infection of multiple serotypes Salmonella. In this study, a flagellin-deficient S. Typhimurium mutant was constructed. Lipopolysaccharide profiles, protein profiles and cryo-electron microscopy revealed that there were no significant differences between the wild-type and mutant OMVs, with the exception of a large amount of flagellin in the wild-type OMVs. Neither the wild-type OMVs nor the non-flagellin OMVs were toxic to macrophages. Mice immunized with the non-flagellin OMVs produced high concentrations of IgG. The non-flagellin OMVs elicited strong mucosal antibody responses in mice when administered via the intranasal route in addition to provoking higher cross-reactive immune responses against OMPs isolated from S. Choleraesuis and S. Enteritidis. Both intranasal and intraperitoneal immunization with the non-flagellin OMVs provided efficient protection against heterologous S. Choleraesuis and S. Enteritidis challenge. Our results indicate that the flagellin-deficient OMVs may represent a new vaccine platform that could be exploited to facilitate the production of a broadly protective vaccine.

Multidrug-Resistant Salmonella enterica Serovar Infantis, Israel

PubMed Central

Valinsky, Lea; Weinberger, Miriam; Guy, Sara; Jaffe, Joseph; Schorr, Yosef Ilan; Raisfeld, Abraham; Agmon, Vered; Nissan, Israel

2010-01-01

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. PMID:21029536

Predicting adhesion and biofilm formation boundaries on stainless steel surfaces by five Salmonella enterica strains belonging to different serovars as a function of pH, temperature and NaCl concentration.

PubMed

Moraes, Juliana O; Cruz, Ellen A; Souza, Enio G F; Oliveira, Tereza C M; Alvarenga, Verônica O; Peña, Wilmer E L; Sant'Ana, Anderson S; Magnani, Marciane

2018-05-26

This study aimed to assess the capability of 97 epidemic S. enterica strains belonging to 18 serovars to form biofilm. Five strains characterized as strong biofilm-producers, belonging to distinct serovars (S. Enteritidis 132, S. Infantis 176, S. Typhimurium 177, S. Heidelberg 281 and S. Corvallis 297) were assayed for adhesion/biofilm formation on stainless steel surfaces. The experiments were conducted in different combinations of NaCl (0, 2, 4, 5, 6, 8 and 10% w/v), pH (4, 5, 6 and 7) and temperatures (8 °C, 12 °C, 20 °C and 35 °C). Only adhesion was assumed to occur when S. enterica counts were ≥3 and <5 log CFU/cm 2 , whereas biofilm formation was defined as when the counts were ≥5 log CFU/cm 2 . The binary responses were used to develop models to predict the probability of adhesion/biofilm formation on stainless steel surfaces by five strains belonging to different S. enterica serovars. A total of 99% (96/97) of the tested S. enterica strains were characterized as biofilm-producers in the microtiter plate assays. The ability to form biofilm varied (P < 0.05) within and among the different serovars. Among the biofilm-producers, 21% (20/96), 45% (43/96), and 35% (34/96) were weak, moderate and strong biofilm-producers, respectively. The capability for adhesion/biofilm formation on stainless steel surfaces under the experimental conditions studied varied among the strains studied, and distinct secondary models were obtained to describe the behavior of the five S. enterica tested. All strains showed adhesion at pH 4 up to 4% of NaCl and at 20 °C and 35 °C. The probability of adhesion decreased when NaCl concentrations were >8% and at 8 °C, as well as in pH values ≤ 5 and NaCl concentrations > 6%, for all tested strains. At pH 7 and 6, biofilm formation for S. Enteritidis, S. Infantis, S. Typhimurium, S. Heidelberg was observed up to 6% of NaCl at 35 °C and 20 °C. The predicted boundaries for adhesion were p

Salmonella Typhimurium grown in a rotating wall bioreactor

NASA Technical Reports Server (NTRS)

2003-01-01

Salmonella typhimurium appears green in on human intestinal tissue (stained red) cultured in a NASA rotating wall bioreactor. Dr. Cheryl Nickerson of Tulane University is studying the effects of simulated low-g on a well-known pathogen, Salmonella typhimurium, a bacterium that causes two to four million cases of gastrointestinal illness in the United States each year. While most healthy people recover readily, S. typhimurium can kill people with weakened immune systems. Thus, a simple case of food poisoning could disrupt a space mission. Using the NASA rotating-wall bioreactor, Nickerson cultured S. typhimurium in modeled microgravity. Mice infected with the bacterium died an average of three days faster than the control mice, indicating that S. typhimurium's virulence was enhanced by the bioreactor. Earlier research showed that 3 percent of the genes were altered by exposure to the bioreactor. Nickerson's work earned her a 2001 Presidential Early Career Award for Scientists and Engineers.

Thermal inactivation of Salmonella Typhimurium in chicken shawirma (gyro).

PubMed

Osaili, Tareq M; Al-Nabulsi, Anas A; Shaker, Reyad R; Olaimat, Amin N; Jaradat, Ziad W; Holley, Richard A

2013-08-16

This study explored the thermal characteristics (D- and z-values) of Salmonella Typhimurium in raw chicken shawirma. Marinated and non-marinated chicken breasts with skin were inoculated with S. Typhimurium 112 or S. Typhimurium 144. Inoculated samples were ground, packed in sterile bags and submerged in a water bath at 54, 56, 58 and 60°C for 2.5 to 72min. The mean D-values of S. Typhimurium strains in inoculated, non-marinated, ground raw chicken breast, as well as those of S. Typhimurium 15h after exposure to the marinade (inoculated before marinating, IBM) or after brief exposure (30min) to the marinade (inoculated after marinating, IAM) ranged from 9.15 to 12.44, 2.89 to 3.92, 1.06 to 1.30 and 0.32 to 0.52min at 54, 56, 58 and 60°C, respectively. Generally, no significant differences (P>0.05) were found among the D-values of S. Typhimurium in all chicken samples. However, the D-values of S. Typhimurium in raw ground chicken shawirma IBM were the lowest. The z-values of S. Typhimurium in all products ranged from 3.78 to 4.58°C. It was concluded that thorough cooking of the outside of the shawirma meat cylinder or cone before removal of slices at foodservice counters can enhance the safety of the product. Copyright © 2013 Elsevier B.V. All rights reserved.

A Salmonella typhimurium-translocated Glycerophospholipid:Cholesterol Acyltransferase Promotes Virulence by Binding to the RhoA Protein Switch Regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaRock, Doris L.; Brzovic, Peter S.; Levin, Itay

Salmonella enterica serovar typhimurium translocates a glycerophospholipid: cholesterol acyltransferase (SseJ) into the host cytosol after its entry into mammalian cells. SseJ is recruited to the cytoplasmic face of the host cell phagosome membrane where it is activated upon binding the small GTPase, RhoA. SseJ is regulated similarly to cognate eukaryotic effectors, as only the GTP-bound form of RhoA family members stimulates enzymatic activity. Using NMR and biochemistry, this work demonstrates that SseJ competes effectively with Rhotekin, ROCK, and PKN1 in binding to a similar RhoA surface. The RhoA surface that binds SseJ includes the regulatory switch regions that control activationmore » of mammalian effectors. These data were used to create RhoA mutants with altered SseJ binding and activation. This structure-function analysis supports a model in which SseJ activation occurs predominantly through binding to residues within switch region II. We further defined the nature of the interaction between SseJ and RhoA by constructing SseJ mutants in the RhoA binding surface. These data indicate that SseJ binding to RhoA is required for recruitment of SseJ to the endosomal network and for full Salmonella virulence for inbred susceptible mice, indicating that regulation of SseJ by small GTPases is an important virulence strategy of this bacterial pathogen. The dependence of a bacterial effector on regulation by a mammalian GTPase defines further how intimately host pathogen interactions have coevolved through similar and divergent evolutionary strategies.« less

Validation of Baking To Control Salmonella Serovars in Hamburger Bun Manufacturing, and Evaluation of Enterococcus faecium ATCC 8459 and Saccharomyces cerevisiae as Nonpathogenic Surrogate Indicators.

PubMed

Channaiah, Lakshmikantha H; Holmgren, Elizabeth S; Michael, Minto; Sevart, Nicholas J; Milke, Donka; Schwan, Carla L; Krug, Matthew; Wilder, Amanda; Phebus, Randall K; Thippareddi, Harshavardhan; Milliken, George

2016-04-01

This study was conducted to validate a simulated commercial baking process for hamburger buns to destroy Salmonella serovars and to determine the appropriateness of using nonpathogenic surrogates (Enterococcus faecium ATCC 8459 or Saccharomyces cerevisiae) for in-plant process validation studies. Wheat flour was inoculated (∼6 log CFU/g) with three Salmonella serovars (Typhimurium, Newport, or Senftenberg 775W) or with E. faecium. Dough was formed, proofed, and baked to mimic commercial manufacturing conditions. Buns were baked for up to 13 min in a conventional oven (218.3°C), with internal crumb temperature increasing to ∼100°C during the first 8 min of baking and remaining at this temperature until removal from the oven. Salmonella and E. faecium populations were undetectable by enrichment (>6-log CFU/g reductions) after 9.0 and 11.5 min of baking, respectively, and ≥5-log-cycle reductions were achieved by 6.0 and 7.75 min, respectively. D-values of Salmonella (three-serovar cocktail) and E. faecium 8459 in dough were 28.64 and 133.33, 7.61 and 55.67, and 3.14 and 14.72 min at 55, 58, and 61°C, respectively, whereas D-values of S. cerevisiae were 18.73, 5.67, and 1.03 min at 52, 55, and 58°C, respectivly. The z-values of Salmonella, E. faecium, and S. cerevisiae were 6.58, 6.25, and 4.74°C, respectively. A high level of thermal lethality was observed for baking of typical hamburger bun dough, resulting in rapid elimination of high levels of the three-strain Salmonella cocktail; however, the lethality and microbial destruction kinetics should not be extrapolated to other bakery products without further research. E. faecium demonstrated greater thermal resistance compared with Salmonella during bun baking and could serve as a conservative surrogate to validate thermal process lethality in commercial bun baking operations. Low thermal tolerance of S. cerevisiae relative to Salmonella serovars limits its usefulness as a surrogate for process validations.

Frequency and duration of fecal shedding of Salmonella serovars Heidelberg and Typhimurium by experimentally infected laying hens housed in enriched colony cages at different stocking densities

USDA-ARS?s Scientific Manuscript database

Eggs contaminated with Salmonella Enteritidis are leading sources of human salmonellosis, but S. Heidelberg and S. Typhimurium are also egg-associated pathogens. The management practices and housing facilities characterizing different systems for housing commercial egg flocks can influence Salmonell...

Complete Proteome of a Quinolone-Resistant Salmonella Typhimurium Phage Type DT104B Clinical Strain

PubMed Central

Correia, Susana; Nunes-Miranda, Júlio D.; Pinto, Luís; Santos, Hugo M.; de Toro, María; Sáenz, Yolanda; Torres, Carmen; Capelo, José Luis; Poeta, Patrícia; Igrejas, Gilberto

2014-01-01

Salmonellosis is one of the most common and widely distributed foodborne diseases. The emergence of Salmonella strains that are resistant to a variety of antimicrobials is a serious global public health concern. Salmonella enterica serovar Typhimurium definitive phage type 104 (DT104) is one of these emerging epidemic multidrug resistant strains. Here we collate information from the diverse and comprehensive range of experiments on Salmonella proteomes that have been published. We then present a new study of the proteome of the quinolone-resistant Se20 strain (phage type DT104B), recovered after ciprofloxacin treatment and compared it to the proteome of reference strain SL1344. A total of 186 and 219 protein spots were recovered from Se20 and SL1344 protein extracts, respectively, after two-dimensional gel electrophoresis. The signatures of 94% of the protein spots were successfully identified through matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS). Three antimicrobial resistance related proteins, whose genes were previously detected by polymerase chain reaction (PCR), were identified in the clinical strain. The presence of these proteins, dihydropteroate synthase type-2 (sul2 gene), aminoglycoside resistance protein A (strA gene) and aminoglycoside 6'-N-acetyltransferase type Ib-cr4 (aac(6')-Ib-cr4 gene), was confirmed in the DT104B clinical strain. The aac(6')-Ib-cr4 gene is responsible for plasmid-mediated aminoglycoside and quinolone resistance. This is a preliminary analysis of the proteome of these two S. Typhimurium strains and further work is being developed to better understand how antimicrobial resistance is developing in this pathogen. PMID:25196519

Genetic Relatedness of Salmonella Serovars Isolated from Catfish (Clarias gariepinus) and Tilapia (Tilapia mossambica) Obtained from Wet Markets and Ponds in Penang, Malaysia.

PubMed

Budiati, Titik; Rusul, Gulam; Wan-Abdullah, Wan Nadiah; Chuah, Li-Oon; Ahmad, Rosma; Thong, Kwai Lin

2016-04-01

A total of 43 Salmonella enterica isolates belonging to different serovars (Salmonella Albany, Salmonella Agona, Salmonella Corvallis, Salmonella Stanley, Salmonella Typhimurium, Salmonella Mikawasima, and Salmonella Bovismorbificans) were isolated from catfish (Clarias gariepinus) and tilapia (Tilapia mossambica) obtained from nine wet markets and eight ponds in Penang, Malaysia. Thirteen, 19, and 11 isolates were isolated from 9 of 32 catfish, 14 of 32 tilapia, and 11 of 44 water samples, respectively. Fish reared in ponds were fed chicken offal, spoiled eggs, and commercial fish feed. The genetic relatedness of these Salmonella isolates was determined by random amplified polymorphic DNA PCR (RAPD-PCR) using primer OPC2, repetitive extragenic palindromic PCR (REP-PCR), and pulsed-field gel electrophoresis (PFGE). Composite analysis of the RAPD-PCR, REP-PCR, and PFGE results showed that the Salmonella serovars could be differentiated into six clusters and 15 singletons. RAPD-PCR differentiated the Salmonella isolates into 11 clusters and 10 singletons, while REP-PCR differentiated them into 4 clusters and 1 singleton. PFGE differentiated the Salmonella isolates into seven clusters and seven singletons. The close genetic relationship of Salmonella isolates from catfish or tilapia obtained from different ponds, irrespective of the type of feed given, may be caused by several factors, such as the quality of the water, density of fish, and size of ponds.

Cantaloupe facilitates transmission of Salmonella typhimurium between adult house flies

USDA-ARS?s Scientific Manuscript database

Salmonella enterica ser. Typhimurium (S. Typhimurium) is a pathogen harbored by livestock that can contaminate fresh produce, such as cantaloupe, and cause food-borne illnesses. We previously demonstrated that house flies acquire and harbor S. Typhimurium after exposure to inoculated cattle manure. ...

Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry.

PubMed

Rana, Namrata; McLean, Samantha; Mann, Brian E; Poole, Robert K

2014-12-01

Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy. © 2014 The Authors.

Fine-tuning synthesis of Yersinia pestis LcrV from runaway-like replication balanced-lethal plasmid in a Salmonella enterica serovar typhimurium vaccine induces protection against a lethal Y. pestis challenge in mice.

PubMed

Torres-Escobar, Ascención; Juárez-Rodríguez, María Dolores; Gunn, Bronwyn M; Branger, Christine G; Tinge, Steven A; Curtiss, Roy

2010-06-01

A balanced-lethal plasmid expression system that switches from low-copy-number to runaway-like high-copy-number replication (pYA4534) was constructed for the regulated delayed in vivo synthesis of heterologous antigens by vaccine strains. This is an antibiotic resistance-free maintenance system containing the asdA gene (essential for peptidoglycan synthesis) as a selectable marker to complement the lethal chromosomal DeltaasdA allele in live recombinant attenuated Salmonella vaccines (RASVs) such as Salmonella enterica serovar Typhimurium strain chi9447. pYA4534 harbors two origins of replication, pSC101 and pUC (low and high copy numbers, respectively). The pUC replication origin is controlled by a genetic switch formed by the operator/promoter of the P22 cro gene (O/P(cro)) (P(R)), which is negatively regulated by an arabinose-inducible P22 c2 gene located on both the plasmid and the chromosome (araC P(BAD) c2). The absence of arabinose, which is unavailable in vivo, triggers replication to a high-copy-number plasmid state. To validate these vector attributes, the Yersinia pestis virulence antigen LcrV was used to develop a vaccine against plague. An lcrV sequence encoding amino acids 131 to 326 (LcrV196) was optimized for expression in Salmonella, flanked with nucleotide sequences encoding the signal peptide (SS) and the carboxy-terminal domain (CT) of beta-lactamase, and cloned into pYA4534 under the control of the P(trc) promoter to generate plasmid pYA4535. Our results indicate that the live Salmonella vaccine strain chi9447 harboring pYA4535 efficiently stimulated a mixed Th1/Th2 immune response that protected mice against lethal challenge with Y. pestis strain CO92 introduced through either the intranasal or subcutaneous route.

Fine-Tuning Synthesis of Yersinia pestis LcrV from Runaway-Like Replication Balanced-Lethal Plasmid in a Salmonella enterica Serovar Typhimurium Vaccine Induces Protection against a Lethal Y. pestis Challenge in Mice▿

PubMed Central

Torres-Escobar, Ascención; Juárez-Rodríguez, María Dolores; Gunn, Bronwyn M.; Branger, Christine G.; Tinge, Steven A.; Curtiss, Roy

2010-01-01

A balanced-lethal plasmid expression system that switches from low-copy-number to runaway-like high-copy-number replication (pYA4534) was constructed for the regulated delayed in vivo synthesis of heterologous antigens by vaccine strains. This is an antibiotic resistance-free maintenance system containing the asdA gene (essential for peptidoglycan synthesis) as a selectable marker to complement the lethal chromosomal ΔasdA allele in live recombinant attenuated Salmonella vaccines (RASVs) such as Salmonella enterica serovar Typhimurium strain χ9447. pYA4534 harbors two origins of replication, pSC101 and pUC (low and high copy numbers, respectively). The pUC replication origin is controlled by a genetic switch formed by the operator/promoter of the P22 cro gene (O/Pcro) (PR), which is negatively regulated by an arabinose-inducible P22 c2 gene located on both the plasmid and the chromosome (araC PBAD c2). The absence of arabinose, which is unavailable in vivo, triggers replication to a high-copy-number plasmid state. To validate these vector attributes, the Yersinia pestis virulence antigen LcrV was used to develop a vaccine against plague. An lcrV sequence encoding amino acids 131 to 326 (LcrV196) was optimized for expression in Salmonella, flanked with nucleotide sequences encoding the signal peptide (SS) and the carboxy-terminal domain (CT) of β-lactamase, and cloned into pYA4534 under the control of the Ptrc promoter to generate plasmid pYA4535. Our results indicate that the live Salmonella vaccine strain χ9447 harboring pYA4535 efficiently stimulated a mixed Th1/Th2 immune response that protected mice against lethal challenge with Y. pestis strain CO92 introduced through either the intranasal or subcutaneous route. PMID:20308296

The Use of a Combined Bioinformatics Approach to Locate Antibiotic Resistance Genes on Plasmids From Whole Genome Sequences of Salmonella enterica Serovars From Humans in Ghana.

PubMed

Kudirkiene, Egle; Andoh, Linda A; Ahmed, Shahana; Herrero-Fresno, Ana; Dalsgaard, Anders; Obiri-Danso, Kwasi; Olsen, John E

2018-01-01

In the current study, we identified plasmids carrying antimicrobial resistance genes in draft whole genome sequences of 16 selected Salmonella enterica isolates representing six different serovars from humans in Ghana. The plasmids and the location of resistance genes in the genomes were predicted using a combination of PlasmidFinder, ResFinder, plasmidSPAdes and BLAST genomic analysis tools. Subsequently, S1-PFGE was employed for analysis of plasmid profiles. Whole genome sequencing confirmed the presence of antimicrobial resistance genes in Salmonella isolates showing multidrug resistance phenotypically. ESBL, either bla TEM52-B or bla CTX-M15 were present in two cephalosporin resistant isolates of S . Virchow and S . Poona, respectively. The systematic genome analysis revealed the presence of different plasmids in different serovars, with or without insertion of antimicrobial resistance genes. In S . Enteritidis, resistance genes were carried predominantly on plasmids of IncN type, in S . Typhimurium on plasmids of IncFII(S)/IncFIB(S)/IncQ1 type. In S . Virchow and in S . Poona, resistance genes were detected on plasmids of IncX1 and TrfA/IncHI2/IncHI2A type, respectively. The latter two plasmids were described for the first time in these serovars. The combination of genomic analytical tools allowed nearly full mapping of the resistance plasmids in all Salmonella strains analyzed. The results suggest that the improved analytical approach used in the current study may be used to identify plasmids that are specifically associated with resistance phenotypes in whole genome sequences. Such knowledge would allow the development of rapid multidrug resistance tracking tools in Salmonella populations using WGS.

Molecular characterization of the Na+/H+-antiporter NhaA from Salmonella Typhimurium.

PubMed

Lentes, Christopher J; Mir, Syed H; Boehm, Marc; Ganea, Constanta; Fendler, Klaus; Hunte, Carola

2014-01-01

Na+/H+ antiporters are integral membrane proteins that are present in almost every cell and in every kingdom of life. They are essential for the regulation of intracellular pH-value, Na+-concentration and cell volume. These secondary active transporters exchange sodium ions against protons via an alternating access mechanism, which is not understood in full detail. Na+/H+ antiporters show distinct species-specific transport characteristics and regulatory properties that correlate with respective physiological functions. Here we present the characterization of the Na+/H+ antiporter NhaA from Salmonella enterica serovar Thyphimurium LT2, the causing agent of food-born human gastroenteritis and typhoid like infections. The recombinant antiporter was functional in vivo and in vitro. Expression of its gene complemented the Na+-sensitive phenotype of an E. coli strain that lacks the main Na+/H+ antiporters. Purified to homogeneity, the antiporter was a dimer in solution as accurately determined by size-exclusion chromatography combined with multi-angle laser-light scattering and refractive index monitoring. The purified antiporter was fully capable of electrogenic Na+(Li+)/H+-antiport when reconstituted in proteoliposomes and assayed by solid-supported membrane-based electrophysiological measurements. Transport activity was inhibited by 2-aminoperimidine. The recorded negative currents were in agreement with a 1Na+(Li+)/2H+ stoichiometry. Transport activity was low at pH 7 and up-regulation above this pH value was accompanied by a nearly 10-fold decrease of KmNa (16 mM at pH 8.5) supporting a competitive substrate binding mechanism. K+ does not affect Na+ affinity or transport of substrate cations, indicating that selectivity of the antiport arises from the substrate binding step. In contrast to homologous E. coli NhaA, transport activity remains high at pH values above 8.5. The antiporter from S. Typhimurium is a promising candidate for combined structural and

Molecular Characterization of the Na+/H+-Antiporter NhaA from Salmonella Typhimurium

PubMed Central

Lentes, Christopher J.; Mir, Syed H.; Boehm, Marc; Ganea, Constanta; Fendler, Klaus; Hunte, Carola

2014-01-01

Na+/H+ antiporters are integral membrane proteins that are present in almost every cell and in every kingdom of life. They are essential for the regulation of intracellular pH-value, Na+-concentration and cell volume. These secondary active transporters exchange sodium ions against protons via an alternating access mechanism, which is not understood in full detail. Na+/H+ antiporters show distinct species-specific transport characteristics and regulatory properties that correlate with respective physiological functions. Here we present the characterization of the Na+/H+ antiporter NhaA from Salmonella enterica serovar Thyphimurium LT2, the causing agent of food-born human gastroenteritis and typhoid like infections. The recombinant antiporter was functional in vivo and in vitro. Expression of its gene complemented the Na+-sensitive phenotype of an E. coli strain that lacks the main Na+/H+ antiporters. Purified to homogeneity, the antiporter was a dimer in solution as accurately determined by size-exclusion chromatography combined with multi-angle laser-light scattering and refractive index monitoring. The purified antiporter was fully capable of electrogenic Na+(Li+)/H+-antiport when reconstituted in proteoliposomes and assayed by solid-supported membrane-based electrophysiological measurements. Transport activity was inhibited by 2-aminoperimidine. The recorded negative currents were in agreement with a 1Na+(Li+)/2H+ stoichiometry. Transport activity was low at pH 7 and up-regulation above this pH value was accompanied by a nearly 10-fold decrease of Km Na (16 mM at pH 8.5) supporting a competitive substrate binding mechanism. K+ does not affect Na+ affinity or transport of substrate cations, indicating that selectivity of the antiport arises from the substrate binding step. In contrast to homologous E. coli NhaA, transport activity remains high at pH values above 8.5. The antiporter from S. Typhimurium is a promising candidate for combined structural and

High-resolution melt-curve analysis of random amplified polymorphic DNA (RAPD-HRM) for the characterisation of pathogenic leptospires: intra-serovar divergence, inter-serovar convergence, and evidence of attenuation in Leptospira reference collections.

PubMed

Tulsiani, S M; Craig, S B; Graham, G C; Cobbold, R C; Dohnt, M F; Burns, M-A; Jansen, C C; Leung, L K-P; Field, H E; Smythe, L D

2010-07-01

High-resolution melt-curve analysis of random amplified polymorphic DNA (RAPD-HRM) is a novel technology that has emerged as a possible method to characterise leptospires to serovar level. RAPD-HRM has recently been used to measure intra-serovar convergence between strains of the same serovar as well as inter-serovar divergence between strains of different serovars. The results indicate that intra-serovar heterogeneity and inter-serovar homogeneity may limit the application of RAPD-HRM in routine diagnostics. They also indicate that genetic attenuation of aged, high-passage-number isolates could undermine the use of RAPD-HRM or any other molecular technology. Such genetic attenuation may account for a general decrease seen in titres of rabbit hyperimmune antibodies over time. Before RAPD-HRM can be further advanced as a routine diagnostic tool, strains more representative of the wild-type serovars of a given region need to be identified. Further, RAPD-HRM analysis of reference strains indicates that the routine renewal of reference collections, with new isolates, may be needed to maintain the genetic integrity of the collections.

Potentiating antibiotics in drug-resistant clinical isolates via stimuli-activated superoxide generation.

PubMed

Courtney, Colleen M; Goodman, Samuel M; Nagy, Toni A; Levy, Max; Bhusal, Pallavi; Madinger, Nancy E; Detweiler, Corrella S; Nagpal, Prashant; Chatterjee, Anushree

2017-10-01

The rise of multidrug-resistant (MDR) bacteria is a growing concern to global health and is exacerbated by the lack of new antibiotics. To treat already pervasive MDR infections, new classes of antibiotics or antibiotic adjuvants are needed. Reactive oxygen species (ROS) have been shown to play a role during antibacterial action; however, it is not yet understood whether ROS contribute directly to or are an outcome of bacterial lethality caused by antibiotics. We show that a light-activated nanoparticle, designed to produce tunable flux of specific ROS, superoxide, potentiates the activity of antibiotics in clinical MDR isolates of Escherichia coli , Salmonella enterica , and Klebsiella pneumoniae . Despite the high degree of antibiotic resistance in these isolates, we observed a synergistic interaction between both bactericidal and bacteriostatic antibiotics with varied mechanisms of action and our superoxide-producing nanoparticles in more than 75% of combinations. As a result of this potentiation, the effective antibiotic concentration of the clinical isolates was reduced up to 1000-fold below their respective sensitive/resistant breakpoint. Further, superoxide-generating nanoparticles in combination with ciprofloxacin reduced bacterial load in epithelial cells infected with S. enterica serovar Typhimurium and increased Caenorhabditis elegans survival upon infection with S. enterica serovar Enteriditis, compared to antibiotic alone. This demonstration highlights the ability to engineer superoxide generation to potentiate antibiotic activity and combat highly drug-resistant bacterial pathogens.

Isolation and genetic characterization of an Actinobacillus pleuropneumoniae serovar K12:O3 strain.

PubMed

Ito, Hiroya; Matsumoto, Atsuko

2015-01-01

An atypical Actinobacillus pleuropneumoniae serovar 12 strain, termed QAS106, was isolated from a clinical case of porcine pleuropneumonia in Japan. An immunodiffusion (ID) test identified the strain as serovar 12. However, the ID test also demonstrated that strain QAS106 shared antigenic determinants with both the serovar 3 and 15 reference strains. Strain QAS106 was positive in the capsular serovar 12-specific polymerase chain reaction (PCR) assay, while the PCR toxin gene profiling and omlA PCR typing assays indicated that strain QAS106 was similar to serovar 3. The nucleotide sequence of the 16S ribosomal DNA (rDNA) of strain QAS106 was identical with that of serovars 3 and 12, but it showed 99.7% identity with that of serovar 15. Nucleotide sequence analysis revealed that genes involved in biosynthesis of the capsular polysaccharide (CPS) of strain QAS106 were identical to those of serovar 12 at the amino acid level. On the other hand, strain QAS106 would express putative proteins involved in the biosynthesis of lipopolysaccharide (LPS) O-polysaccharide (O-PS), the amino acid sequences of which were identical or nearly identical to those of serovars 3 and 15. In conclusion, strain QAS106 should be recognized as K12:O3, even though typical serovar 12 strains are K12:O12. The emergence of an atypical A. pleuropneumoniae serovar 12 strain expressing a rare combination of CPS and O-PS antigens would hamper precise serodiagnosis by the use of either CPS- or LPS-based serodiagnostic methodology alone. © 2014 The Author(s).

Genetic and antigenic characteristics of ApxIIA and ApxIIIA from Actinobacillus pleuropneumoniae serovars 2, 3, 4, 6, 8 and 15.

PubMed

To, Ho; Nagai, Shinya; Iwata, Akira; Koyama, Tomohiro; Oshima, Atsushi; Tsutsumi, Nobuyuki

2016-07-01

Apx toxins produced by Actinobacillus pleuropneumoniae are essential components of new generation vaccines. In this study, apxIIA and apxIIIA genes of serovars 2, 3, 4, 6, 8 and 15 were cloned and sequenced. Amino acid sequences of ApxIIA proteins of serovars 2, 3, 4, 6, 8 and 15 were almost identical to those of serovars 1, 5, 7, 9 and 11-13. Immunoblot analysis showed that rApxIIA from serovars 2 and 15 reacts strongly with sera from animals infected with various serovars. Sequence analysis revealed that ApxIIIA proteins has two variants, one in strains of serovar 2 and the other in strains of serovars 3, 4, 6, 8 and 15. A mouse cross-protection study showed that mice actively immunized with rApxIIIA/2 or rApxIIIA/15 are protected against challenge with A. pleuropneumoniae strains of serovars 3, 4, 6, 8, 15, and 2 expressing ApxIII/15 and ApxIII/2, respectively. Similarly, mice passively immunized with rabbit anti-rApxIIIA/2 or anti-rApxIIIA/15 sera were found to be protected against challenge with strains of serovars 2 and 15. Our study revealed antigenic and sequence similarities within ApxIIA and ApxIIIA proteins, which may help in the development of effective vaccines against disease caused by A. pleuropneumoniae. © 2016 The Societies and John Wiley & Sons Australia, Ltd.

Leptospira santorosai Serovar Shermani detergent extract induces an increase in fibronectin production through a Toll-like receptor 2-mediated pathway.

PubMed

Tian, Ya-Chung; Hung, Cheng-Chieh; Li, Yi-Jung; Chen, Yung-Chang; Chang, Ming-Yang; Yen, Tzung-Hai; Hsu, Hsiang-Hao; Wu, Mai-Szu; Phillips, Aled; Yang, Chih-Wei

2011-03-01

Leptospirosis can activate inflammatory responses through Toll-like receptors (TLRs) and may cause renal tubulointerstitial fibrosis characterized by the accumulation of extracellular matrix (ECM). We have previously demonstrated that Leptospira santorosai serovar Shermani detergent extract stimulates ECM accumulation in vitro. The aim of this study was to examine the mechanistic basis of these previous observations and, in particular, to examine the potential involvement of TLRs. The addition of serovar Shermani detergent extract led to an increase in fibronectin gene expression and production. Inhibition of TLR2 but not TLR4 expression abrogated serovar Shermani detergent extract-mediated increases in fibronectin production. This response was also blocked by the knockdown of the gene expression of the TLR2 downstream transducers myeloid differentiation factor 88 (MyD88) and tumor necrosis factor receptor-associated factor 6 (TRAF6). Serovar Shermani detergent extract also activated nuclear factor-κB, and its inhibition by curcumin-attenuated serovar Shermani detergent extract induced increases in fibronectin production. These effects were also mimicked by the specific TLR2 agonist, Pam(3)CsK(4), a response that was also abrogated by the knockdown of MyD88 and TRAF6. Similarly, the administration of live leptospires to cells also induced fibronectin production that was blocked by inhibition of TLR2 and MyD88 expression. In conclusion, serovar Shermani detergent extract can induce fibronectin production through the TLR2-associated cascade, providing evidence of an association between TLRs and leptospirosis-mediated ECM deposition.

Antibacterial activity of red algae (Gracilaria verrucosa) extract against Escherichia coli and Salmonella typhimurium

NASA Astrophysics Data System (ADS)

Dayuti, S.

2018-04-01

Red alga was widely used in several fields, including food, feed, phamacy and industrial point of view. The chemical analysis showed that red alga contained terpenoid, acetogenic, and aromatic compounds, which have a wide range of biological activities, such as anti-micobial, anti-inflammatory and anti-viral. The objectives of this research was to evaluate the effect of extraction solvent and time on antibacterial activity of red alga (Gracilaria verrucosa), and to explore the bioactive compound contained within Gracilaria verrucosa. The method in this study used descriptive reseach. These findings revealed that the highest inhibition activity among all extracts was obtained with the ratio of methanol:aquades (75:25) and extraction time around 72 hours against Escherichia coli and Salmonella typhimurium. The bioactive compounds of Gracilaria verrucosa tested by phytochemical analysisi consisted of flavonoid, alkaloid, and saponin. Those secondary metabolites may be approximated as antibactial substances.

The emergence of Leptospira borgpetersenii serovar Arborea in Queensland, Australia, 2001 to 2013.

PubMed

Lau, Colleen L; Skelly, Chris; Dohnt, Michael; Smythe, Lee D

2015-06-14

Leptospirosis is an emerging infectious disease, with increasing frequency and severity of outbreaks, changing epidemiology of populations at risk, and the emergence of new serovars. Environmental drivers of disease transmission include flooding, urbanisation, poor sanitation, changes in land use and agricultural practices, and socioeconomic factors. In Queensland, human infection with Leptosira borgpetersenii serovar Arborea was first reported in 2001. This study aims to report the emergence of serovar Arborea in Queensland from 2001 to 2013, and investigate potential risk factors for infection and drivers of emergence. Data on laboratory-confirmed cases of human leptospirosis in Queensland were obtained from the enhanced surveillance system at the WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis in Brisbane, Australia. The changing epidemiology of serovar Arborea from 2001 to 2003 was described with respect to case numbers, proportion of leptospirosis cases attributed to the serovar, and geographic distribution. Differences in risk factors for the most common serovars were compared. During this period, 1289 cases of leptospirosis were reported, including 233 cases attributed to serovar Arborea. Risk factors for infection include male gender (91 % of cases), occupation, and recreational exposure. Most common occupations recorded were banana workers (28.4 %), meat workers (7.2 %), dairy farmers (5.8 %), graziers/stockmen (5.5 %), 'other agricultural/rural workers' (16.4 %), and tourists or tourism operators (4.6 %). Time trend analysis showed that while non-Arborea cases decreased over the study period, Arborea cases increased by 3.4 cases per year. The proportion of annual cases attributed to Arborea peaked at 49 % in 2011 after unprecedented flooding in Queensland. Mapping of cases by residential location showed expansion of the geographic range of serovar Arborea, concentrating mostly around Brisbane, Cairns and Innisfail. Serovars

Salmonella Serovars from Humans and Other Sources in Thailand, 1993–2002

PubMed Central

Bangtrakulnonth, Aroon; Pornreongwong, Srirat; Pulsrikarn, Chaiwat; Sawanpanyalert, Pathom; Hendriksen, Rene S.; Wong, Danilo M. A. Lo Fo

2004-01-01

We serotyped 44,087 Salmonella isolates from humans and 26,148 from other sources from 1993 through 2002. The most common serovar causing human salmonellosis in Thailand was Salmonella enterica Weltevreden. Serovars causing human infections in Thailand differ from those in other countries and seem to be related to Salmonella serovars in different food products and reservoirs. PMID:15078609

Strain Selection for Generation of O-Antigen-Based Glycoconjugate Vaccines against Invasive Nontyphoidal Salmonella Disease

PubMed Central

Saul, Allan; MacLennan, Calman A.; Micoli, Francesca; Rondini, Simona

2015-01-01

Nontyphoidal Salmonellae, principally S. Typhimurium and S. Enteritidis, are a major cause of invasive bloodstream infections in sub-Saharan Africa with no vaccine currently available. Conjugation of lipopolysaccharide O-antigen to a carrier protein constitutes a promising vaccination strategy. Here we describe a rational process to select the most appropriate isolates of Salmonella as source of O-antigen for developing a bivalent glycoconjugate vaccine. We screened a library of 30 S. Typhimurium and 21 S. Enteritidis in order to identify the most suitable strains for large scale O-antigen production and generation of conjugate vaccines. Initial screening was based on growth characteristics, safety profile of the isolates, O-antigen production, and O-antigen characteristics in terms of molecular size, O-acetylation and glucosylation level and position, as determined by phenol sulfuric assay, NMR, HPLC-SEC and HPAEC-PAD. Three animal isolates for each serovar were identified and used to synthesize candidate glycoconjugate vaccines, using CRM197 as carrier protein. The immunogenicity of these conjugates and the functional activity of the induced antibodies was investigated by ELISA, serum bactericidal assay and flow cytometry. S. Typhimurium O-antigen showed high structural diversity, including O-acetylation of rhamnose in a Malawian invasive strain generating a specific immunodominant epitope. S. Typhimurium conjugates provoked an anti-O-antigen response primarily against the O:5 determinant. O-antigen from S. Enteritidis was structurally more homogeneous than from S. Typhimurium, and no idiosyncratic antibody responses were detected for the S. Enteritidis conjugates. Of the three initially selected isolates, two S. Typhimurium (1418 and 2189) and two S. Enteritidis (502 and 618) strains generated glycoconjugates able to induce high specific antibody levels with high breadth of serovar-specific strain coverage, and were selected for use in vaccine production. The

Distribution of Salmonella Serovars and Antimicrobial Susceptibility from Poultry and Swine Farms in Central Vietnam.

PubMed

Lettini, A A; Vo Than, T; Marafin, E; Longo, A; Antonello, K; Zavagnin, P; Barco, L; Mancin, M; Cibin, V; Morini, M; Dang Thi Sao, M; Nguyen Thi, T; Pham Trung, H; Le, L; Nguyen Duc, T; Ricci, A

2016-11-01

This study was conducted to estimate the prevalence of Salmonella spp. and their antimicrobial susceptibilities on poultry and swine farms, sampled in 2 regions in Central Vietnam. A total of 67 poultry farms and 46 swine farms were sampled in a period of 5 months (from September 2012 to January 2013). Salmonella spp. was prevalent in 46.3% and 71.7% of poultry and swine farms, respectively. Altogether, 99 non-typhoidal Salmonella were isolated and the most common serovars were Salmonella Weltevreden (19%), followed by Salmonella Typhimurium (12%) and Salmonella 4,[5],12:i:- (11%). Overall, 71 of 99 (72%) Salmonella isolates were resistant to at least one of the 14 antimicrobial agents tested. Both in poultry and swine farms, high levels of resistance were observed for ampicillin, chloramphenicol, ciprofloxacin, sulphamethoxazole and tetracycline. The presence of Salmonella isolates from poultry and swine farms which were resistant to different classes of antimicrobials suggests that alternative control measures to antimicrobials should be implemented. Moreover, an effective policy should be promoted to encourage a prudent use of these agents in animal farming in Vietnam. © 2016 Blackwell Verlag GmbH.

Survival of foodborne pathogenic bacteria (Bacillus cereus, Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Listeria monocytogenes) and Bacillus cereus spores in fermented alcoholic beverages (beer and refined rice wine).

PubMed

Kim, S A; Kim, N H; Lee, S H; Hwang, I G; Rhee, M S

2014-03-01

Only limited information is available on the microbiological safety of fermented alcoholic beverages because it is still a common belief that such beverages do not provide a favorable environment for bacterial growth and survival. Thus, in this study, we examined the survival of major foodborne pathogens and spores in fermented alcoholic beverages. Foodborne pathogens (Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus) and B. cereus spores (initial population, 3 to 4 log CFU/ml) were inoculated separately into three types of beer and refined rice wine, which were then stored at 5 and 22°C. Bacterial counts were assayed periodically for up to 28 days. Vegetative B. cereus counts decreased rapidly, whereas B. cereus spore counts remained constant (P > 0.05) for a long period of time in all beverages. Vegetative B. cereus cells formed spores in beer at 5 and 22°C, and the spores survived for long periods. Among vegetative cells, E. coli O157:H7 had the highest survival (only 1.49 to 1.56 log reduction during 28 days in beer at 5°C). Beer and refined rice wine supported microbial survival from several days to several weeks. Our results appear to contradict the common belief that pathogens cannot survive in alcoholic beverages. Long-term survival of pathogens (especially B. cereus and E. coli O157:H7) in beer and refined rice wine should be taken into consideration by the manufacturers of these beverages. This study provides basic information that should help further research into microbial survival in alcoholic beverages and increase the microbiological safety regulation of fermented alcoholic beverages.

Seaweed extracts and galacto-oligosaccharides improve intestinal health in pigs following Salmonella Typhimurium challenge.

PubMed

Bouwhuis, M A; McDonnell, M J; Sweeney, T; Mukhopadhya, A; O'Shea, C J; O'Doherty, J V

2017-09-01

Pork and pork products are recognised as vehicles of Salmonella Typhimurium infection in humans. Seaweed-derived polysaccharides (SWE) and galacto-oligosaccharides (GOS) have shown to exhibit antimicrobial, prebiotic and immunomodulatory activity. The objective of this study was to assess the effects of dietary GOS and SWE supplementation on reducing S. Typhimurium numbers and intestinal inflammation in vivo. In total, 30 pigs (n=10/treatment, BW 30.9 kg) were randomly assigned to three dietary treatments: (1) basal diet; (2) basal diet+2.5 g GOS/kg diet; (3) basal diet+SWE (containing 180 mg laminarin/kg diet+340 mg fucoidan/kg diet). Following an 11-day dietary adaptation period, pigs were orally challenged with 108 colony-forming units/ml S. Typhimurium (day 0). Pigs remained on their diets for a further 17 days and were then sacrificed for sample collection. The SWE supplementation did not affect S. Typhimurium numbers on days 2 and 4 post-challenge but reduced S. Typhimurium numbers in faecal samples collected day 7 post-challenge (-0.80 log gene copy numbers (GCN)/g faeces) and in caecal and colonic digesta (-0.62 and -0.98 log GCN/g digesta, respectively; P<0.05) compared with the control treatment. Lactobacillus numbers were increased in caecal and colonic digesta after GOS supplementation (+0.70 and +0.35 log GCN/g digesta, respectively; P<0.05). In colonic tissue, both GOS and SWE supplementation resulted in reduced messenger RNA expression levels of interleukin (IL)-6, IL-22, tumour necrosis factor-α and regenerating islet-derived protein 3-γ (P<0.05). It can be concluded that dietary supplementation of SWE reduced faecal and intestinal S. Typhimurium numbers compared with the basal diet, whereas dietary GOS supplementation increased Lactobacillus numbers in caecal and colonic digesta but did not affect S. Typhimurium numbers. Supplementation of GOS and SWE reduced the gene expression of pro-inflammatory cytokines in colonic tissue of pigs after the

Transcriptional response of turkeys to MDR Salmonella enterica serovar heidelberg

USDA-ARS?s Scientific Manuscript database

Food-producing animals such as swine, cattle and poultry are a major reservoir of the human foodborne pathogen Salmonella. While some Salmonella serovars can cause disease in food-producing animals, most serovars colonize these animals asymptomatically, resulting in the hosts becoming carriers and ...

Application of genetically engineered Salmonella typhimurium for interferon-gamma-induced therapy against melanoma.

PubMed

Yoon, Wonsuck; Park, Yoo Chang; Kim, Jinseok; Chae, Yang Seok; Byeon, Jung Hye; Min, Sang-Hyun; Park, Sungha; Yoo, Young; Park, Yong Keun; Kim, Byeong Mo

2017-01-01

Salmonella have been experimentally used as anti-cancer agents, because they show selective growth in tumours. In this study, we genetically modified attenuated Salmonella typhimurium to express and secrete interferon-gamma (IFN-γ) as a tumouricidal agent to enhance the therapeutic efficacy of Salmonella. IFN-γ was fused to the N-terminal region (residues 1-160) of SipB (SipB160) for secretion from bacterial cells. Attenuated S. typhimurium expressing recombinant IFN-γ (S. typhimurium (IFN-γ)) invaded the melanoma cells and induced cytotoxicity. Subcutaneous administration of S. typhimurium (IFN-γ) also efficiently inhibited tumour growth and prolonged the survival of C57BL/6 mice bearing B16F10 melanoma compared with administration of phosphate-buffered saline (PBS), unmodified S. typhimurium or S. typhimurium expressing empty vector (S. typhimurium [Vec]) in a natural killer (NK) cell-dependent manner. Moreover, genetically modified Salmonella, including S. typhimurium (IFN-γ), showed little toxicity to normal tissues with no observable adverse effects. However, S. typhimurium (IFN-γ)-mediated tumour suppression was attributed to direct killing of tumour cells rather than to stable anti-tumour immunity. Collectively, these results suggest that tumour-targeted therapy using S. typhimurium (IFN-γ) has potential for melanoma treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Haemophilus parasuis serovars isolated from pathological samples in Northern Italy.

PubMed

Luppi, A; Bonilauri, P; Dottori, M; Iodice, G; Gherpelli, Y; Merialdi, G; Maioli, G; Martelli, P

2013-04-01

From January 2007 to December 2011, a total of 106 Haemophilus parasuis strains isolated from pigs were serotyped by agar gel diffusion test (DG). Serovar 4 was the most prevalent (24.5%), followed by serovar 13 (19.8%) and serovar 5 (11.3%). Twenty-nine strains were non-typeable (27.3%). The strains were divided into two groups, depending on whether they were isolated from specific pathological lesions of systemic disease such as polyserositis, arthritis or meningitis (73 cases of 106) or from the lower respiratory tract of pigs suffering from bronchopneumonia (33 cases of 106). Serovars 4 and 13 had a higher prevalence in systemic infection (polyserositis) than in respiratory disease only. Pasteurella multocida (14/106), Streptococcus suis (7/106), Actinobacillus pleuropneumoniae (4/106), Bordetella bronchiseptica (3/106) and Arcanobacterium pyogenes (3/106) were isolated in association with H. parasuis. © 2012 Blackwell Verlag GmbH.

Comparative susceptibility of Salmonella Typhimurium biofilms of different ages to disinfectants.

PubMed

Wong, Hui San; Townsend, Kirsty M; Fenwick, Stan G; Maker, Garth; Trengove, Robert D; O'Handley, Ryan M

2010-10-01

There is a general consensus that with increasing age a biofilm shows increased resistance to antimicrobials. In this study the susceptibility of 3-, 5- and 7-day-old Salmonella enterica serovar Typhimurium biofilms to disinfectants was evaluated. It was hypothesized that 7-day-old biofilms would be more resistant to disinfectants compared to 3- and 5-day-old biofilms. Biofilms were formed using the MBEC™ system and treated with six chemical disinfectants for 1 and 5 min. Four disinfectants at the highest concentration available showed 100% reduction in viable cells from all ages of biofilms after exposure for 5 min, and ethanol at 70% v/v was the least effective against biofilms, followed by chlorhexidine gluconate (CG). At the recommended user concentrations, only sodium hypochlorite showed 100% reduction in viable cells from all ages of biofilms. Benzalkonium chloride and CG were the least effective against biofilms, followed by quaternary ammonium compound which only showed 100% reduction in viable cells from 5-day-old biofilms. Overall, the results from this study do not display enhanced resistance in 7-day-old biofilms compared to 3- and 5-day-old biofilms. It is concluded that under the conditions of this study, the age of biofilm did not contribute to resistance towards disinfectants. Rather, the concentration of disinfectant and an increased contact time were both shown to play a role in successful sanitization.

Three New Lactobacillus plantarum Strains in the Probiotic Toolbox against Gut Pathogen Salmonella enterica Serotype Typhimurium

PubMed Central

Potočnjak, Mia; Pušić, Petra; Frece, Jadranka; Abram, Maja; Janković, Tamara

2017-01-01

Summary The benefits of probiotic bacteria have been widely explored. However, fermented foods and digestive system of humans and animals are an inexhaustible source of new potentially probiotic microorganisms. In this study we present three new Lactobacillus plantarum strains isolated from different dairy products: cow′s cheese, sheep′s cheese and whey. In order to determine the antibacterial activity of yet unexplored L. plantarum strains against Salmonella enterica serotype Typhimurium, in vitro competition and co-culture tests were done. Furthermore, adhesion of these strains to Caco-2 cells and their influence on the adhesion of Salmonella were tested. Results showed the potential probiotic activity of isolated strains. L. plantarum strains survived in the presence of 1% bile salts, they possessed acidification ability, antibacterial activity and significantly attenuated the growth of S. Typhimurium in brain heart infusion broth. All tested L. plantarum strains were able to adhere to Caco-2 cells and significantly impair the adhesion of S. Typhimurium. All three L. plantarum strains exhibited significant probiotic potential and anti-Salmonella activity; therefore, further testing on in vivo models should follow. PMID:28559733

Characterization of Isolates of Salmonella enterica Serovar Stanley, a Serovar Endemic to Asia and Associated with Travel

PubMed Central

Le Hello, Simon; Bortolaia, Valeria; Pulsrikarn, Chaiwat; Nielsen, Eva Møller; Pornruangmong, Srirat; Chaichana, Phattharaporn; Svendsen, Christina Aaby; Weill, François-Xavier; Aarestrup, Frank M.

2012-01-01

Salmonella enterica serovar Stanley (S. Stanley) is a common serovar in Southeast Asia and was the second most common serovar implicated in human salmonellosis in Thailand in the years 2002 to 2007. In contrast, this serovar is relatively uncommon in Europe. The objective of this study was to characterize a collection of S. Stanley strains isolated from Thai (n = 62), Danish (n = 39), and French (n = 24) patients to gain a broader understanding of the genetic diversity, population dynamics, and susceptibility to antimicrobials. All isolates were characterized by pulsed-field gel electrophoresis and antimicrobial susceptibility testing. The molecular mechanisms of resistance to extended-spectrum cephalosporins and plasmid-mediated resistance to quinolones were characterized by PCR and sequencing. Plasmid profiling, replicon typing, and microarray analysis were used to characterize the genetic mechanisms of antimicrobial resistance in 10 extended-spectrum cephalosporinase-producing isolates. Considerable genetic diversity was observed among the isolates characterized with 91 unique XbaI pulsed-field gel electrophoresis (PFGE) patterns, including 17 distinct clusters consisting of two to seven indistinguishable isolates. We found some of the S. Stanley isolates isolated from patients in Europe were acquired during travel to Southeast Asia, including Thailand. The presence of multiple plasmid lineages carrying the extended-spectrum cephalosporinase-encoding blaCMY-2 gene in S. Stanley isolates from the central part of Thailand was confirmed. Our results emphasize that Thai authorities, as well as authorities in other countries lacking prudent use of antimicrobials, should improve the ongoing efforts to regulate antimicrobial use in agriculture and in clinical settings to limit the spread of multidrug-resistant Salmonella isolates and plasmids among humans and pigs in Thailand and abroad. PMID:22205822

Characterization of isolates of Salmonella enterica serovar Stanley, a serovar endemic to Asia and associated with travel.

PubMed

Hendriksen, Rene S; Le Hello, Simon; Bortolaia, Valeria; Pulsrikarn, Chaiwat; Nielsen, Eva Møller; Pornruangmong, Srirat; Chaichana, Phattharaporn; Svendsen, Christina Aaby; Weill, François-Xavier; Aarestrup, Frank M

2012-03-01

Salmonella enterica serovar Stanley (S. Stanley) is a common serovar in Southeast Asia and was the second most common serovar implicated in human salmonellosis in Thailand in the years 2002 to 2007. In contrast, this serovar is relatively uncommon in Europe. The objective of this study was to characterize a collection of S. Stanley strains isolated from Thai (n = 62), Danish (n = 39), and French (n = 24) patients to gain a broader understanding of the genetic diversity, population dynamics, and susceptibility to antimicrobials. All isolates were characterized by pulsed-field gel electrophoresis and antimicrobial susceptibility testing. The molecular mechanisms of resistance to extended-spectrum cephalosporins and plasmid-mediated resistance to quinolones were characterized by PCR and sequencing. Plasmid profiling, replicon typing, and microarray analysis were used to characterize the genetic mechanisms of antimicrobial resistance in 10 extended-spectrum cephalosporinase-producing isolates. Considerable genetic diversity was observed among the isolates characterized with 91 unique XbaI pulsed-field gel electrophoresis (PFGE) patterns, including 17 distinct clusters consisting of two to seven indistinguishable isolates. We found some of the S. Stanley isolates isolated from patients in Europe were acquired during travel to Southeast Asia, including Thailand. The presence of multiple plasmid lineages carrying the extended-spectrum cephalosporinase-encoding bla(CMY-2) gene in S. Stanley isolates from the central part of Thailand was confirmed. Our results emphasize that Thai authorities, as well as authorities in other countries lacking prudent use of antimicrobials, should improve the ongoing efforts to regulate antimicrobial use in agriculture and in clinical settings to limit the spread of multidrug-resistant Salmonella isolates and plasmids among humans and pigs in Thailand and abroad.

Inflammasome activation causes dual recruitment of NLRC4 and NLRP3 to the same macromolecular complex.

PubMed

Man, Si Ming; Hopkins, Lee J; Nugent, Eileen; Cox, Susan; Glück, Ivo M; Tourlomousis, Panagiotis; Wright, John A; Cicuta, Pietro; Monie, Tom P; Bryant, Clare E

2014-05-20

Pathogen recognition by nucleotide-binding oligomerization domain-like receptor (NLR) results in the formation of a macromolecular protein complex (inflammasome) that drives protective inflammatory responses in the host. It is thought that the number of inflammasome complexes forming in a cell is determined by the number of NLRs being activated, with each NLR initiating its own inflammasome assembly independent of one another; however, we show here that the important foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) simultaneously activates at least two NLRs, whereas only a single inflammasome complex is formed in a macrophage. Both nucleotide-binding domain and leucine-rich repeat caspase recruitment domain 4 and nucleotide-binding domain and leucine-rich repeat pyrin domain 3 are simultaneously present in the same inflammasome, where both NLRs are required to drive IL-1β processing within the Salmonella-infected cell and to regulate the bacterial burden in mice. Superresolution imaging of Salmonella-infected macrophages revealed a macromolecular complex with an outer ring of apoptosis-associated speck-like protein containing a caspase activation and recruitment domain and an inner ring of NLRs, with active caspase effectors containing the pro-IL-1β substrate localized internal to the ring structure. Our data reveal the spatial localization of different components of the inflammasome and how different members of the NLR family cooperate to drive robust IL-1β processing during Salmonella infection.

Invasive Non-Typhoidal Salmonella Typhimurium ST313 Are Not Host-Restricted and Have an Invasive Phenotype in Experimentally Infected Chickens

PubMed Central

Parsons, Bryony N.; Humphrey, Suzanne; Salisbury, Anne Marie; Mikoleit, Julia; Hinton, Jay C. D.; Gordon, Melita A.; Wigley, Paul

2013-01-01

Salmonella enterica serovar Typhimurium Sequence Type (ST) 313 is a major cause of invasive non-Typhoidal salmonellosis in sub-Saharan Africa. No animal reservoir has been identified, and it has been suggested that ST313 is adapted to humans and transmission may occur via person-to-person spread. Here, we show that ST313 cause severe invasive infection in chickens as well as humans. Oral infection of chickens with ST313 isolates D23580 and Q456 resulted in rapid infection of spleen and liver with all birds infected at these sites by 3 days post-infection. In contrast, the well-defined ST19 S. Typhimurium isolates F98 and 4/74 were slower to cause invasive disease. Both ST19 and ST313 caused hepatosplenomegaly, and this was most pronounced in the ST313-infected animals. At 3 and 7 days post-infection, colonization of the gastrointestinal tract was lower in birds infected with the ST313 isolates compared with ST19. Histological examination and expression of CXCL chemokines in the ileum showed that both D23580 (ST313) and 4/74 (ST19) strains caused increased CXCL expression at 3 days post-infection, and this was significantly higher in the ileum of D23580 vs 4/74 infected birds. At 7 days post-infection, reduced chemokine expression occurred in the ileum of the D23580 but not 4/74-infected birds. Histological analysis showed that D23580 infection resulted in rapid inflammation and pathology including villous flattening and fusion at 3 days post-infection, and subsequent resolution by 7 days. In contrast, 4/74 induced less inflammation and pathology at 3 days post-infection. The data presented demonstrate that ST313 is capable of causing invasive disease in a non-human host. The rapid invasive nature of infection in the chicken, coupled with lower gastrointestinal colonization, supports the hypothesis that ST313 is a distinct pathovariant of S. Typhimurium that has evolved to become a systemic pathogen that can cause disease in several hosts. PMID:24130915

Igg Subclasses Targeting the Flagella of Salmonella enterica Serovar Typhimurium Can Mediate Phagocytosis and Bacterial Killing

PubMed Central

Goh, Yun Shan; Armour, Kathryn L; Clark, Michael R; Grant, Andrew J; Mastroeni, Pietro

2016-01-01

Invasive non-typhoidal Salmonella are a common cause of invasive disease in immuno-compromised individuals and in children. Multi-drug resistance poses challenges to disease control, with a critical need for effective vaccines. Flagellin is an attractive vaccine candidate due to surface exposure and high epitope copy number, but its potential as a target for opsonophacytic antibodies is unclear. We examined the effect of targeting flagella with different classes of IgG on the interaction between Salmonella Typhimurium and a human phagocyte-like cell line, THP-1. We tagged the FliC flagellar protein with a foreign CD52 mimotope (TSSPSAD) and bacteria were opsonized with a panel of humanised CD52 antibodies with the same antigen-binding V-region, but different constant regions. We found that IgG binding to flagella increases bacterial phagocytosis and reduces viable intracellular bacterial numbers. Opsonisation with IgG3, followed by IgG1, IgG4, and IgG2, resulted in the highest level of bacterial uptake and in the highest reduction in the intracellular load of viable bacteria. Taken together, our data provide proof-of-principle evidence that targeting flagella with antibodies can increase the antibacterial function of host cells, with IgG3 being the most potent subclass. These data will assist the rational design of urgently needed, optimised vaccines against iNTS disease. PMID:27366588

Sugar sulfates are not hydrolyzed by the acid-inducible sulfatase AslA from Salmonella enterica Enteritidis NalR and Kentucky 3795 at pH 5.5.

PubMed

Ganguly, Arpeeta; Joerger, Rolf D

2017-08-01

The open reading frames SEN0085 and SeKA_A4361, from Salmonella enterica serovar Enteritidis Nal R and serovar Kentucky 3795, respectively, corresponding to the acid-inducible sulfatase gene aslA from Salmonella enterica serovar Typhimurium, were previously suggested by microarray analysis to be differentially expressed under acid conditions. However, growth and enzyme activity tests in the present study demonstrated that both wild-type strains exhibited sulfatase activity with 4-nitrophenyl sulfate and 5-bromo-4-chloro-3 indolyl sulfate at pH 5.5. The acid sulfatase does not appear to be involved in sugar sulfate, tyrosine sulfate, 4-hydroxy-3-methoxyphenylglycol sulfate, heparin sulfate, or chondroitin sulfate hydrolysis at pH 5.5. Adhesion and invasion assays did not reveal differences between the serotypes and their corresponding aslA deletion mutants. Thus, the role and substrate(s) of AslA, a protein unique to salmonella and encoded in all sequenced Salmonella strains, remain elusive.

Investigation of the Role of Genes Encoding Zinc Exporters zntA, zitB, and fieF during Salmonella Typhimurium Infection.

PubMed

Huang, Kaisong; Wang, Dan; Frederiksen, Rikki F; Rensing, Christopher; Olsen, John E; Fresno, Ana H

2017-01-01

The transition metal zinc is involved in crucial biological processes in all living organisms and is essential for survival of Salmonella in the host. However, little is known about the role of genes encoding zinc efflux transporters during Salmonella infection. In this study, we constructed deletion mutants for genes encoding zinc exporters ( zntA , zitB , and fieF ) in the wild-type (WT) strain Salmonella enterica serovar Typhimurium ( S. Typhimurium) 4/74. The mutants 4/74Δ zntA and 4/74Δ zntA/zitB exhibited a dramatic growth delay and abrogated growth ability, respectively, in Luria Bertani medium supplemented with 0.25 mM ZnCl 2 or 1.5 mM CuSO 4 compared to the WT strain. In order to investigate the role of genes encoding zinc exporters on survival of S. Typhimurium inside cells, amoeba and macrophage infection models were used. No significant differences in uptake or survival were detected for any of the mutants compared to the WT during infection of amoebae. In natural resistance-associated macrophage protein 1 (Nramp1)-negative J774.1 murine macrophages, significantly higher bacterial counts were observed for the mutant strains 4/74Δ zntA and 4/74Δ zntA/zitB compared to the WT at 4 h post-infection although the fold net replication was similar between all the strains. All four tested mutants (4/74Δ zntA , 4/74Δ zitB , 4/74Δ fieF , and 4/74Δ zntA/zitB ) showed enhanced intracellular survival capacity within the modified Nramp1-positive murine RAW264.7 macrophages at 20 h post-infection. The fold net replication was also significantly higher for 4/74Δ zntA , 4/74Δ zitB , and 4/74Δ zntA/zitB mutants compared to the WT. Intriguingly, the ability to survive and cause infection was significantly impaired in all the three mutants tested (4/74Δ zntA , 4/74Δ zitB , and 4/74Δ zntA/zitB ) in C3H/HeN mice, particularly the double mutant 4/74Δ zntA/zitB was severely attenuated compared to the WT in all the three organs analyzed. These findings suggest

Salmonella in the pork production chain and its impact on human health in the European Union.

PubMed

Bonardi, S

2017-06-01

Salmonella spp. comprise the second most common food-borne pathogens in the European Union (EU). The role of pigs as carriers of Salmonella has been intensively studied both on farm and at slaughter. Salmonella infection in pigs may cause fever, diarrhoea, prostration and mortality. However, most infected pigs remain healthy carriers, and those infected at the end of the fattening period could pose a threat to human health. Contamination of pig carcasses can occur on the slaughter line, and it is linked to cross-contamination from other carcasses and the presence of Salmonella in the environment. Therefore, Salmonella serovars present on pig carcasses can be different from those detected in the same bathes on the farm. In recent years, S. Typhimurium, S. Derby and S. serotype 4,[5],12:i:- (a monophasic variant of S. Typhimurium) have been the most common serovars to be detected in pigs in EU countries, but S. Rissen, S. Infantis, S. Enteritidis and S. Brandenburg have also been reported. In humans, several cases of salmonellosis have been linked to the consumption of raw or undercooked pork and pork products. Among the main serovars of porcine origin detected in confirmed human cases, S. Typhimurium, the monophasic variant S. 4,[5],12:i:- and S. Derby are certainly the most important.

Serovar Diversity of Pathogenic Leptospira Circulating in the French West Indies

PubMed Central

Bourhy, Pascale; Herrmann Storck, Cécile; Theodose, Rafaelle; Olive, Claude; Nicolas, Muriel; Hochedez, Patrick; Lamaury, Isabelle; Zinini, Farida; Brémont, Sylvie; Landier, Annie; Cassadou, Sylvie; Rosine, Jacques; Picardeau, Mathieu

2013-01-01

Background Leptospirosis is one of the most important neglected tropical bacterial diseases in Latin America and the Caribbean. However, very little is known about the circulating etiological agents of leptospirosis in this region. In this study, we describe the serological and molecular features of leptospires isolated from 104 leptospirosis patients in Guadeloupe (n = 85) and Martinique (n = 19) and six rats captured in Guadeloupe, between 2004 and 2012. Methods and Findings Strains were studied by serogrouping, PFGE, MLVA, and sequencing 16SrRNA and secY. DNA extracts from blood samples collected from 36 patients in Martinique were also used for molecular typing of leptospires via PCR. Phylogenetic analyses revealed thirteen different genotypes clustered into five main clades that corresponded to the species: L. interrogans, L. kirschneri, L. borgpetersenii, L. noguchi, and L. santarosai. We also identified L. kmetyi in at least two patients with acute leptospirosis. This is the first time, to our knowledge, that this species has been identified in humans. The most prevalent genotypes were associated with L. interrogans serovars Icterohaemorrhagiae and Copenhageni, L. kirschneri serovar Bogvere, and L. borgpetersenii serovar Arborea. We were unable to identify nine strains at the serovar level and comparison of genotyping results to the MLST database revealed new secY alleles. Conclusions The overall serovar distribution in the French West Indies was unique compared to the neighboring islands. Typing of leptospiral isolates also suggested the existence of previously undescribed serovars. PMID:23516654

Viability and Virulence of Experimentally Stressed Nonculturable Salmonella typhimurium

PubMed Central

Caro, Audrey; Got, Patrice; Lesne, Jean; Binard, Sylvie; Baleux, Bernard

1999-01-01

Maintenance of pathogenicity of viable but nonculturable Salmonella typhimurium cells experimentally stressed with UV-C and seawater, was investigated relative to the viability level of the cellular population. Pathogenicity, tested in a mouse model, was lost concomitantly with culturability, whereas cell viability remained undamaged, as determined by respiratory activity and cytoplasmic membrane and genomic integrities. PMID:10388726

Distribution of Salmonella serovars in breeding, nursery, and grow-to-finish pigs, and risk factors for shedding in ten farrow-to-finish swine farms in Alberta and Saskatchewan.

PubMed

Wilkins, Wendy; Rajić, Andrijana; Waldner, Cheryl; McFall, Margaret; Chow, Eva; Muckle, Anne; Rosengren, Leigh

2010-04-01

The study objectives were to investigate Salmonella prevalence, serovar distribution, and risk factors for shedding in 10 purposively selected farrow-to-finish farms in Saskatchewan and Alberta. Pooled fecal samples from the breeding and grow-finish phases and individual fecal samples from breeding, nursery, and grow-finish pigs were cultured for Salmonella; serotyping of isolates was performed. Pig and pen characteristics were recorded for each pig and pen sampled.Overall, 407/1143 (36%) of samples were Salmonella positive; within-farm prevalence ranged from 1% to 79%. Sows, nursery, and grow-finish pigs accounted for 43%, 29%, and 28% of positive samples, respectively. More Salmonella were detected in pooled pen than individual pig samples (P < 0.001). Among 418 Salmonella isolates, there were 19 distinct serovars; the most common were S. Derby (28.5%), S. Typhimurium, var. Copenhagen (19.1%), S. Putten (11.8%), S. Infantis (6.8%), and S. Mbandaka (6.1%). Sows were more likely to shed Salmonella than nursery or grow-finisher (OR 2.9, P < 0.001) pigs. Pelleted feed (OR 8.2, P < 0.001) and nose-to-nose pig contact through pens (OR 2.2, P = 0.005) were associated with increased Salmonella prevalence. Significant differences in serovar distribution were detected among production phases. The use of pooled pen samples is recommended as a more efficient means for accurate evaluation of Salmonella status in different phases of pig production. The breeding herd might be an important source of Salmonella persistence within farrow-to-finish farms and should be targeted in control efforts. The latter might also apply to the use of pelleted feed, which remains the most consistently reported significant risk factor for Salmonella shedding in pigs.

Identification and characterization of haemagglutinin epitopes of Avibacterium paragallinarum serovar C.

PubMed

Noro, Taichi; Oishi, Eiji; Kaneshige, Takahiro; Yaguchi, Kazuhiko; Amimoto, Katsuhiko; Shimizu, Mitsugu

2008-10-15

The objectives of this study were to identify haemagglutinin (HA) epitopes of Avibacterium paragallinarum serovar C that are capable of eliciting haemagglutination inhibition (HI) antibody, and to investigate their immunogenic role. Three conformational epitopes were detected on HA by blocking ELISA and immuno-dot blot analysis using a panel of five monoclonal antibodies (MAbs) with HI activity, designated 8C1C, 4G8B, 24E4D, 11E11B, and 10D1A. The minimum DNA regions coding these three epitopes were 3195, 2862, and 807bp in size, and mapped within a gene with 6117bp. Nine DNA fragments of various lengths were prepared, and their recombinant proteins were generated in E. coli. One recombinant protein, designated HPC5.5, was recognized by MAb 8C1C, and had strong ability to adsorb HI antibody to Av. paragallinarum serovar C. Other recombinant proteins designated HPC5.1, HPC4.8, and HPC2.5 did not react with MAb 8C1C and only slightly adsorbed HI antibody. All chickens immunized once with HPC5.5 did not show any typical clinical signs such as nasal discharge or facial edema against challenge inoculation with Av. paragallinarum serovar C. However, HPC5.1, which was recognized by four MAbs (not including MAb 8C1C), showed only partial protective immunity in five of eight immunized chickens. The results suggest that the HA epitope recognized by MAb 8C1C is the major epitope responsible for eliciting HI antibody, and HPC5.5 is a practical candidate protein to develop a new vaccine against avian infectious coryza caused by Av. paragallinarum serovar C.

Chasing Salmonella Typhimurium in free range egg production system.

PubMed

Chousalkar, Kapil; Gole, Vaibhav; Caraguel, Charles; Rault, Jean-Loup

2016-08-30

Free range production systems are becoming a major source of egg production in Australia and worldwide. This study investigated shedding and ecology of Salmonella Typhimurium and Salmonella species in a free range layer flock, wild birds and foxes in the vicinity of the free range farm in different seasons. Shedding of Salmonella was significantly higher in summer. Within the shed, overall, Salmonella prevalence was highest in dust. Corticosterone level in faeces was highest in spring and lowest in winter. There was no direct association between the Salmonella shedding (MPN/gm) and corticosterone levels in faeces. Salmonella Typhimurium MLVA types isolated from fox and wild birds were similar to MLVA types isolated from layer flock and reported during human food borne illness. Wild birds and foxes appear to play an important role in S. Typhimurium ecology and food safety. Environmental factors could play a role in evolution of S. Typhimurium in free range environment. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Contribution of Asparagine Catabolism to Salmonella Virulence

PubMed Central

McLaughlin, Patrick A.; McClelland, Michael; Yang, Hee-Jeong; Porwollik, Steffen; Bogomolnaya, Lydia; Chen, Juei-Suei; Andrews-Polymenis, Helene

2016-01-01

ABSTRACT Salmonellae are pathogenic bacteria that cause significant morbidity and mortality in humans worldwide. Salmonellae establish infection and avoid clearance by the immune system by mechanisms that are not well understood. We previously showed that l-asparaginase II produced by Salmonella enterica serovar Typhimurium (S. Typhimurium) inhibits T cell responses and mediates virulence. In addition, we previously showed that asparagine deprivation such as that mediated by l-asparaginase II of S. Typhimurium causes suppression of activation-induced T cell metabolic reprogramming. Here, we report that STM3997, which encodes a homolog of disulfide bond protein A (dsbA) of Escherichia coli, is required for l-asparaginase II stability and function. Furthermore, we report that l-asparaginase II localizes primarily to the periplasm and acts together with l-asparaginase I to provide S. Typhimurium the ability to catabolize asparagine and assimilate nitrogen. Importantly, we determined that, in a murine model of infection, S. Typhimurium lacking both l-asparaginase I and II genes competes poorly with wild-type S. Typhimurium for colonization of target tissues. Collectively, these results indicate that asparagine catabolism contributes to S. Typhimurium virulence, providing new insights into the competition for nutrients at the host-pathogen interface. PMID:27849183

Contribution of Asparagine Catabolism to Salmonella Virulence.

PubMed

McLaughlin, Patrick A; McClelland, Michael; Yang, Hee-Jeong; Porwollik, Steffen; Bogomolnaya, Lydia; Chen, Juei-Suei; Andrews-Polymenis, Helene; van der Velden, Adrianus W M

2017-02-01

Salmonellae are pathogenic bacteria that cause significant morbidity and mortality in humans worldwide. Salmonellae establish infection and avoid clearance by the immune system by mechanisms that are not well understood. We previously showed that l-asparaginase II produced by Salmonella enterica serovar Typhimurium (S Typhimurium) inhibits T cell responses and mediates virulence. In addition, we previously showed that asparagine deprivation such as that mediated by l-asparaginase II of S Typhimurium causes suppression of activation-induced T cell metabolic reprogramming. Here, we report that STM3997, which encodes a homolog of disulfide bond protein A (dsbA) of Escherichia coli, is required for l-asparaginase II stability and function. Furthermore, we report that l-asparaginase II localizes primarily to the periplasm and acts together with l-asparaginase I to provide S Typhimurium the ability to catabolize asparagine and assimilate nitrogen. Importantly, we determined that, in a murine model of infection, S Typhimurium lacking both l-asparaginase I and II genes competes poorly with wild-type S Typhimurium for colonization of target tissues. Collectively, these results indicate that asparagine catabolism contributes to S Typhimurium virulence, providing new insights into the competition for nutrients at the host-pathogen interface. Copyright © 2017 American Society for Microbiology.

Antimutagenicity of Methanolic Extracts from Anemopsis californica in Relation to Their Antioxidant Activity

PubMed Central

Del-Toro-Sánchez, Carmen Lizette; Bautista-Bautista, Nereyda; Blasco-Cabal, José Luis; Gonzalez-Ávila, Marisela; Gutiérrez-Lomelí, Melesio; Arriaga-Alba, Myriam

2014-01-01

Anemopsis californica has been used empirically to treat infectious diseases. However, there are no antimutagenic evaluation reports on this plant. The present study evaluated the antioxidant activity in relation to the mutagenic and antimutagenic activity properties of leaf (LME) and stem (SME) methanolic extracts of A. californica collected in the central Mexican state of Querétaro. Antioxidant properties and total phenols of extracts were evaluated using DPPH (1,1-diphenyl-2-picrylhydrazyl) and Folin-Ciocalteu methods, respectively. Mutagenicity was evaluated using the Ames test employing Salmonella enterica serovar Typhimurium strains (TA98, TA100, and TA102), with and without an aroclor 1254 (S9 mixture). Antimutagenesis was performed against mutations induced on the Ames test with MNNG, 2AA, or 4NQO. SME presented the highest antioxidant capacity and total phenolic content. None of the extracts exhibited mutagenicity in the Ames test. The extracts produced a significant reduction in 2AA-induced mutations in S. typhimurium TA98. In both extracts, mutagenesis induced by 4NQO or methyl-N′-nitro-N-nitrosoguanidine (MNNG) was reduced only if the exposure of strains was <10 μg/Petri dish. A. californca antioxidant properties and its capacity to reduce point mutations render it suitable to enhance medical cancer treatments. The significant effect against antimutagenic 2AA suggests that their consumption would provide protection against carcinogenic polycyclic aromatic compounds. PMID:25152760

Metabolism of Exogenous Purine Bases and Nucleosides by Salmonella typhimurium

PubMed Central

Hoffmeyer, J.; Neuhard, J.

1971-01-01

Purine-requiring mutants of Salmonella typhimurium LT2 containing additional mutations in either adenosine deaminase or purine nucleoside phosphorylase have been constructed. From studies of the ability of these mutants to utilize different purine compounds as the sole source of purines, the following conclusions may be drawn. (i) S. typhimurium does not contain physiologically significant amounts of adenine deaminase and adenosine kinase activities. (ii) The presence of inosine and guanosine kinase activities in vivo was established, although the former activity appears to be of minor significance for inosine metabolism. (iii) The utilization of exogenous purine deoxyribonucleosides is entirely dependent on a functional purine nucleoside phosphorylase. (iv) The pathway by which exogenous adenine is converted to guanine nucleotides in the presence of histidine requires a functional purine nucleoside phosphorylase. Evidence is presented that this pathway involves the conversion of adenine to adenosine, followed by deamination to inosine and subsequent phosphorolysis to hypoxanthine. Hypoxanthine is then converted to inosine monophosphate by inosine monophosphate pyrophosphorylase. The rate-limiting step in this pathway is the synthesis of adenosine from adenine due to lack of endogenous ribose-l-phosphate. PMID:4928005

Multidrug-resistant strains of Salmonella enterica Typhimurium, United States, 1997-1998.

PubMed

Rabatsky-Ehr, Therese; Whichard, Jean; Rossiter, Shannon; Holland, Ben; Stamey, Karen; Headrick, Marcia L; Barrett, Timothy J; Angulo, Frederick J

2004-05-01

To evaluate multidrug-resistant strains of Salmonella enterica serotype Typhimurium, including definitive type 104 (DT104) in the United States, we reviewed data from the National Antimicrobial Resistance Monitoring System (NARMS). In 1997 to 1998, 703 (25%) of 2,767 serotyped Salmonella isolates received at NARMS were S. Typhimurium; antimicrobial susceptibility testing and phage typing were completed for 697. Fifty-eight percent (402) were resistant to > or = 1 antimicrobial agent. Three multidrug-resistant (> or = 5 drugs) strains accounted for (74%) 296 of all resistant isolates. Ceftriaxone resistance was present in 8 (3%), and nalidixic acid resistance in 4 (1%), of these multidrug-resistant strains. By phage typing, 259 (37%) of S. Typhimurium isolates were DT104, 209 (30%) were of undefined type and 103 (15%) were untypable. Fifty percent (202) of resistant (> or = 1 drug) isolates were DT104. Multidrug-resistant S. Typhimurium isolates, particularly DT104, account for a substantial proportion of S. Typhimurium isolates; ceftriaxone resistance is exhibited by some of these strains.

Saccharomyces boulardii modifies Salmonella typhimurium traffic and host immune responses along the intestinal tract.

PubMed

Pontier-Bres, Rodolphe; Munro, Patrick; Boyer, Laurent; Anty, Rodolphe; Imbert, Véronique; Terciolo, Chloé; André, Fréderic; Rampal, Patrick; Lemichez, Emmanuel; Peyron, Jean-François; Czerucka, Dorota

2014-01-01

Salmonella enterica serovar Typhimurium (ST) is an enteropathogenic Gram-negative bacterium that causes infection following oral ingestion. ST spreads rapidly along the gastrointestinal tract (GIT) and invades the intestinal epithelium to ultimately reach internal body organs. The probiotic yeast Saccharomyces boulardii BIOCODEX (S.b-B) is prescribed for prophylaxis of diarrheal infectious diseases. We previously showed that S.b-B prevents weight loss in ST-infected mice and significantly decreases bacterial translocation to the spleen and liver. This study was designed to investigate the effect of S.b-B on ST migration along the GIT and the impact of the yeast on the host's early innate immune responses. Bioluminescent imaging (BLI) was used to evaluate the effect of S.b-B on the progression of luminescent Salmonella Typhimurium (ST-lux) in the GIT of mice pretreated with streptomycin. Photonic emission (PE) was measured in GIT extracts (stomach, small intestine, cecum and colon) at various time periods post-infection (PI). PE analysis revealed that, 45 min PI, ST-lux had migrated slightly faster in the mice treated with S.b-B than in the untreated infected animals. At 90 min PI, ST-lux had reached the cecum in both groups of mice. Adhesion of ST to S.b-B was visualized in the intestines of the mice and probably accounts for (1) the faster elimination of ST-lux in the feces, and (2) reduced translocation of ST to the spleen and liver. In the early phase of infection, S.b-B also modifies the host's immune responses by (1) increasing IFN-γ gene expression and decreasing IL-10 gene expression in the small intestine, and (2) elevating both IFN-γ, and IL-10 mRNA levels in the cecum. BLI revealed that S.b-B modifies ST migration and the host immune response along the GIT. Study findings shed new light on the protective mechanisms of S.b-B during the early phase of Salmonella pathogenesis.

Comparative Study on Antibiotic Resistance and DNA Profiles of Salmonella enterica Serovar Typhimurium Isolated from Humans, Retail Foods, and the Environment in Shanghai, China.

PubMed

Zhang, Zengfeng; Cao, Chenyang; Liu, Bin; Xu, Xuebin; Yan, Yanfei; Cui, Shenghui; Chen, Sheng; Meng, Jianghong; Yang, Baowei

2018-05-09

We characterized antibiotic resistance profiles, antibiotic resistance-associated genes, and pulsed-field gel electrophoresis (PFGE) patterns of 145 Salmonella enterica serotype Typhimurium isolates from human infections and retail foods that were possibly responsible for salmonellosis outbreaks from 2008 to 2012 in Shanghai, China. Resistance to at least three antibiotics was found in 66.7% of chicken isolates, 76.5% of duck isolates, 77.8% of pork isolates, and 80.5% of human isolates. Seven antibiotic resistance phenotypes were detected in chicken isolates, 16 in pork isolates, 17 in duck isolates, and 50 in human isolates. No significant difference (p > 0.05) was found between Salmonella isolates derived from human salmonellosis and from retail foods in terms of the percent resistance of ampicillin, amoxicillin/clavulanic acid, ceftiofur, ceftriaxone, nalidixic acid, chloramphenicol, gentamicin, kanamycin, streptomycin, tetracycline, sulfisoxazole, and sulfamethoxazole/trimethoprim. PFGE using XbaI and BlnI showed that some Salmonella isolates recovered from human infections and retail foods had same or highly similar genetic profile. Same or similar antibiotic resistance profiles, antibiotic resistance associated genes (i.e., qnrA, qnrB, qnrS, aac(6')-Ib, and oqxAB), gene cassettes (i.e., aadA2, dfrA12-aadA2, and aadA1), and mutations were detected in those isolates that exhibited high genetic similarities. These findings highlighted the frequent presence of Salmonella Typhimurium in retail chicken, pork, duck, and humans.

Mechanism of Antibacterial Activities of a Rice Hull Smoke Extract (RHSE) Against Multidrug-Resistant Salmonella Typhimurium In Vitro and in Mice.

PubMed

Kim, Sung Phil; Lee, Sang Jong; Nam, Seok Hyun; Friedman, Mendel

2018-02-01

The present study tested antibacterial activity of a rice hull smoke extract (RHSE) against a multidrug-resistant strain of Salmonella Typhimurium and examined its mode of suppressive action in vitro and in mice. In vitro studies showed that the minimum inhibitory concentration (MIC) value of RHSE was 1.29% (v/v). The inactivation was confirmed by complete loss of cell viability in the range of 10 4 to 10 7 colony forming units of the resistant Salmonella Typhimurium strain. Agarose and sodium dodecyl sulfate-polyacrylamide gel electrophoreses were used to evaluate the integrities of bacterial genomic DNA and total cellular protein profiles. The antibacterial action of RHSE results from a leakage of intracellular macromolecules following rupture of bacterial cells. Scanning electron microscopy of the cells shows that RHSE also induced deleterious morphological changes in the bacterial cell membrane of the pathogens. In vivo antibacterial activity of RHSE at a 1 × MIC concentration was examined in a bacterial gastroenteritis model using Balb/c mice orally infected with the Salmonella Typhimurium. The results show greatly decreased excretion of the bacteria into the feces and suppressed translocation of the bacteria to internal organs (cecum, mesenteric lymph node, spleen, and liver) compared with the infected mice not subjected to the RHSE treatment. Collectively, the present findings indicate that the mechanism of the antibacterial activities both in vitro and in the gastroenteritis environment of the animal model is the result of the direct disruption of cell structure, leading to cell death. RHSE has the potential to serve as a multifunctional food additive that might protect consumers against infections by antibiotic-resistant microorganisms. The rice hull derived liquid smoke has the potential to complement widely used wood-derived smoke as an antimicrobial flavor and health-promoting formulation for application in foods and feeds. Published 2017. This article

Diversity of pulsed-field gel electrophoresis pulsotypes, serovars, and antibiotic resistance among Salmonella isolates from wild amphibians and reptiles in the California Central Coast.

PubMed

Gorski, Lisa; Jay-Russell, Michele T; Liang, Anita S; Walker, Samarpita; Bengson, Yingjia; Govoni, Jessica; Mandrell, Robert E

2013-06-01

A survey of cold-blooded vertebrates and associated surface waters in a produce-growing region on the Central California Coast was done between May and September 2011 to determine the diversity of Salmonella. Samples from 460 amphibians and reptiles and 119 water samples were collected and cultured for Salmonella. Animals sampled were frogs (n=331), lizards (n=59), newts (n=5), salamanders (n=6), snakes (n=39), and toads (n=20). Salmonella was isolated from 37 individual animals, including frogs, lizards, snakes, and toads. Snakes were the most likely to contain Salmonella, with 59% testing positive followed by 15.3% of lizards, 5% of toads, and 1.2% of frogs. Fifteen water samples (12.6%) were positive. Twenty-two different serovars were identified, and the majority of isolates were S. enterica subsp. IIIb, with subsp. I, II, and IIIa also found. The serovar isolated most frequently was S. enterica subsp. IIIb 16:z₁₀:e,n,x,z₁₅, from snakes and frogs in five different locations. S. enterica subsp. I serovar Typhimurium and the monophasic I 6,8:d:- were isolated from water, and subspecies I Duisburg and its variants were found in animals and water. Some samples contained more than one type of Salmonella. Analysis of pulsed-field gel electrophoresis pulsotypes indicated that some strains persisted in animals and water collected from the same location. Sixty-six isolates displayed antibiotic resistance, with 27 isolates resistant to more than one antibiotic, including a subspecies IIIb isolate from snake having resistance to five different antibiotics. Twenty-three isolates were resistant to more than one class of antibiotic, and six isolates were resistant to three classes. While these subspecies of IIIa and IIIb cause fewer instances of human illness, they may serve as reservoirs of antibiotic resistance, determinants in the environment, and be sources of contamination of leafy greens associated with product recalls.

Comparison of Genotypes of Salmonella enterica Serovar Enteritidis Phage Type 30 and 9c Strains Isolated during Three Outbreaks Associated with Raw Almonds▿

PubMed Central

Parker, Craig T.; Huynh, Steven; Quiñones, Beatriz; Harris, Linda J.; Mandrell, Robert E.

2010-01-01

In 2000 to 2001, 2003 to 2004, and 2005 to 2006, three outbreaks of Salmonella enterica serovar Enteritidis were linked with the consumption of raw almonds. The S. Enteritidis strains from these outbreaks had rare phage types (PT), PT30 and PT9c. Clinical and environmental S. Enteritidis strains were subjected to pulsed-field gel electrophoresis (PFGE), multilocus variable-number tandem repeat analysis (MLVA), and DNA microarray-based comparative genomic indexing (CGI) to evaluate their genetic relatedness. All three methods differentiated these S. Enteritidis strains in a manner that correlated with PT. The CGI analysis confirmed that the majority of the differences between the S. Enteritidis PT9c and PT30 strains corresponded to bacteriophage-related genes present in the sequenced genomes of S. Enteritidis PT4 and S. enterica serovar Typhimurium LT2. However, PFGE, MLVA, and CGI failed to discriminate between S. Enteritidis PT30 strains related to outbreaks from unrelated clinical strains or between strains separated by up to 5 years. However, metabolic fingerprinting demonstrated that S. Enteritidis PT4, PT8, PT13a, and clinical PT30 strains metabolized l-aspartic acid, l-glutamic acid, l-proline, l-alanine, and d-alanine amino acids more efficiently than S. Enteritidis PT30 strains isolated from orchards. These data indicate that S. Enteritidis PT9c and 30 strains are highly related genetically and that PT30 orchard strains differ from clinical PT30 strains metabolically, possibly due to fitness adaptations. PMID:20363782

Regulation of the Salmonella enterica std fimbrial operon by DNA adenine methylation, SeqA, and HdfR.

PubMed

Jakomin, Marcello; Chessa, Daniela; Bäumler, Andreas J; Casadesús, Josep

2008-11-01

DNA adenine methylase (dam) mutants of Salmonella enterica serovar Typhimurium grown under laboratory conditions express the std fimbrial operon, which is tightly repressed in the wild type. Here, we show that uncontrolled production of Std fimbriae in S. enterica serovar Typhimurium dam mutants contributes to attenuation in mice, as indicated by the observation that an stdA dam strain is more competitive than a dam strain upon oral infection. Dam methylation appears to regulate std transcription, rather than std mRNA stability or turnover. A genetic screen for std regulators showed that the GATC-binding protein SeqA directly or indirectly represses std expression, while the poorly characterized yifA gene product serves as an std activator. YifA encodes a putative LysR-like protein and has been renamed HdfR, like its Escherichia coli homolog. Activation of std expression by HdfR is observed only in dam and seqA backgrounds. These data suggest that HdfR directly or indirectly activates std transcription. Since SeqA is unable to bind nonmethylated DNA, it is possible that std operon derepression in dam and seqA mutants may result from unconstrained HdfR-mediated activation of std transcription. Derepression of std in dam and seqA mutants of S. enterica occurs in only a fraction of the bacterial population, suggesting the occurrence of either bistable expression or phase variation.

Complete genome sequence of Leptospira alstonii serovar room 22, strain GWTS#1

USDA-ARS?s Scientific Manuscript database

We report the complete genome sequence of Leptospira alstonii serovar room 22 strain GWTS#1. This is the first isolate of L. alstonii to be cultured from a mammal, in Western Europe, and represents a new serovar of pathogenic leptospires....

Serovar distribution of a DNA sequence involved in the antigenic relationship between Leptospira and equine cornea.

PubMed

Lucchesi, Paula M A; Parma, Alberto E; Arroyo, Guillermo H

2002-01-01

Horses infected with Leptospira present several clinical disorders, one of them being recurrent uveitis. A common endpoint of equine recurrent uveitis is blindness. Serovar pomona has often been incriminated, although others have also been reported. An antigenic relationship between this bacterium and equine cornea has been described in previous studies. A leptospiral DNA fragment that encodes cross-reacting epitopes was previously cloned and expressed in Escherichia coli. A region of that DNA fragment was subcloned and sequenced. Samples of leptospiral DNA from several sources were analysed by PCR with two primer pairs designed to amplify that region. Reference strains from serovars canicola, icterohaemorrhagiae, pomona, pyrogenes, wolffi, bataviae, sentot, hebdomadis and hardjo rendered products of the expected sizes with both pairs of primers. The specific DNA region was also amplified from isolates from Argentina belonging to serogroups Canicola and Pomona. Both L. biflexa serovar patoc and L. borgpetersenii serovar tarassovi rendered a negative result. The DNA sequence related to the antigen mimicry with equine cornea was not exclusively found in serovar pomona as it was also detected in several strains of Leptospira belonging to different serovars. The results obtained with L. biflexa serovar patoc strain Patoc I and L. borgpetersenii serovar tarassovi strain Perepelicin suggest that this sequence is not present in these strains, which belong to different genomospecies than those which gave positive results. This is an interesting finding since L. biflexa comprises nonpathogenic strains and serovar tarassovi has not been associated clinically with equine uveitis.

Host Specificity of Salmonella typhimurium Deoxyribonucleic Acid Restriction and Modification

PubMed Central

Slocum, Harvey; Boyer, Herbert W.

1973-01-01

The restriction and modification genes of Salmonella typhimurium which lie near the thr locus were transferred to a restrictionless mutant of Escherichia coli. These genes were found to be allelic to the E. coli K, B, and A restriction and modification genes. E. coli recombinants with the restriction and modification host specificity of S. typhimurium restricted phage λ that had been modified by each of the seven known host specificities of E. coli at efficiency of plating levels of about 10−2. Phage λ modified with the S. typhimurium host specificity was restricted by six of the seven E. coli host specificities but not by the RII (fi− R-factor controlled) host specificity. It is proposed that the restriction and modification enzymes of this S. typhimurium host specificity have two substrates, one of which is a substrate for the RII host specificity enzymes. PMID:4570605

Molecular Characterization of Multiresistant d-Tartrate-Positive Salmonella enterica Serovar Paratyphi B Isolates

PubMed Central

Miko, Angelika; Guerra, Beatriz; Schroeter, Andreas; Dorn, Christina; Helmuth, Reiner

2002-01-01

Since 1996, the National Salmonella Reference Laboratory of Germany has received an increasing number of Salmonella enterica subsp. enterica serovar Paratyphi B isolates. Nearly all of these belonged to the dextrorotatory tartrate-positive variant (S. enterica subsp. enterica serovar Paratyphi B dT+), formerly called S. enterica subsp. enterica serovar Java. A total of 55 selected contemporary and older S. enterica subsp. enterica serovar Paratyphi B dT+ isolates were analyzed by plasmid profiling, antimicrobial resistance testing, pulsed-field gel electrophoresis, IS200 profiling, and PCR-based detection of integrons. The results showed a high genetic heterogeneity among 10 old strains obtained from 1960 to 1993. In the following years, however, new distinct multiresistant S. enterica subsp. enterica serovar Paratyphi B dT+ clones emerged, and one clonal lineage successfully displaced the older ones. Since 1994, 88% of the isolates investigated were multiple drug resistant. Today, a particular clone predominates in some German poultry production lines, poultry products, and various other sources. It was also detected in contemporary isolates from two neighboring countries as well. PMID:12202551

Orally administered live attenuated Salmonella Typhimurium protects mice against lethal infection with H1N1 influenza virus.

PubMed

Kamble, Nitin Machindra; Hajam, Irshad Ahmed; Lee, John Hwa

2017-03-01

Pre-stimulation of toll-like receptors (TLRs) by agonists has been shown to increase protection against influenza virus infection. In this study, we evaluated the protective response generated against influenza A/Puerto Rico/8/1934 (PR8; H1N1) virus by oral and nasal administration of live attenuated Salmonella enterica serovar Typhimurium, JOL911 strain, in mice. Oral and nasal inoculation of JOL911 significantly increased the mRNA copy number of TLR-2, TLR4 and TLR5, and downstream type I interferon (IFN) molecules, IFN-α and IFN-β, both in peripheral blood mononuclear cells (PBMCs) and in lung tissue. Similarly, the mRNA copy number of interferon-inducible genes (ISGs), Mx and ISG15, were significantly increased in both the orally and the nasally inoculated mice. Post PR8 virus lethal challenge, the nasal JOL911 and the PBS control group mice showed significant loss of body weight with 70% and 100% mortality, respectively, compared to only 30% mortality in the oral JOL911 group mice. Post sub-lethal challenge, the significant reduction in PR8 virus copy number in lung tissue was observed in oral [on day 4 and 6 post-challenge (dpc)] and nasal (on 4dpc) than the PBS control group mice. The lethal and sub-lethal challenge showed that the generated stimulated innate resistance (StIR) in JOL911 inoculated mice conferred resistance to acute and initial influenza infection but might not be sufficient to prevent the PR8 virus invasion and replication in the lung. Overall, the present study indicates that oral administration of attenuated S. Typhimurium can pre-stimulate multiple TLR pathways in mice to provide immediate early StIR against a lethal H1N1 virus challenge. Copyright © 2017 Elsevier B.V. All rights reserved.

In vitro and in vivo probiotic assessment of Leuconostoc mesenteroides P45 isolated from pulque, a Mexican traditional alcoholic beverage.

PubMed

Giles-Gómez, Martha; Sandoval García, Jorge Giovanni; Matus, Violeta; Campos Quintana, Itzia; Bolívar, Francisco; Escalante, Adelfo

2016-01-01

Pulque is a Mexican traditional alcoholic, non-distilled, fermented beverage produced by the fermentation of the sap, known as aguamiel, extracted from several maguey (Agave) species. Pulque has traditionally been considered a healthy beverage due to its nutrient content and also a traditional medicine for the treatment of gastrointestinal disorders and intestinal infections. During pulque fermentation, the development of acidity, alcohol and viscosity define its final sensorial properties, developing an enriched environment where dominant lactic acid bacteria (LAB), including diverse Leuconostoc species, are present. Because traditional pulque is consumed directly from the fermentation vessel, the naturally associated LAB are ingested and reach the human small intestine alive. Here, we report the in vitro and in vivo probiotic assessment of Leuconostoc mesenteroides strain P45 isolated from pulque. This isolated LAB species exhibited lysozyme, acid (pH 3.5) and bile salts (0.1 and 0.3 % oxgall) resistance. Antibacterial activity against the pathogens Listeria monocytogenes, enteropathogenic Escherichia coli, Salmonella enterica serovar Typhi and S. enterica serovar Typhimurium were observed in assays involving cell-to-cell contact, cell-free 2× concentrated supernatants and cell-to-cell contact under exopolysaccharide-producing conditions. The in vivo probiotic assessment showed an anti-infective activity of L. mesenteroides P45 against S. enterica serovar Typhimurium in challenged male and female BALB/c mice. Analysis of the available genome sequence of strain P45 allowed identified a pre-bacteriocin coding gene and six peptidoglycan hydrolase enzymes, probably involved in the antimicrobial activity of this strain. The results presented in this study support some potential microbial mechanisms associated with the beneficial effects on human health of this LAB involved in the fermentation of pulque.

Sublethal exposure to commercial formulations of the herbicides dicamba, 2,4-dichlorophenoxyacetic acid, and glyphosate cause changes in antibiotic susceptibility in Escherichia coli and Salmonella enterica serovar Typhimurium.

PubMed

Kurenbach, Brigitta; Marjoshi, Delphine; Amábile-Cuevas, Carlos F; Ferguson, Gayle C; Godsoe, William; Gibson, Paddy; Heinemann, Jack A

2015-03-24

Biocides, such as herbicides, are routinely tested for toxicity but not for sublethal effects on microbes. Many biocides are known to induce an adaptive multiple-antibiotic resistance phenotype. This can be due to either an increase in the expression of efflux pumps, a reduced synthesis of outer membrane porins, or both. Exposures of Escherichia coli and Salmonella enterica serovar Typhimurium to commercial formulations of three herbicides-dicamba (Kamba), 2,4-dichlorophenoxyacetic acid (2,4-D), and glyphosate (Roundup)-were found to induce a changed response to antibiotics. Killing curves in the presence and absence of sublethal herbicide concentrations showed that the directions and the magnitudes of responses varied by herbicide, antibiotic, and species. When induced, MICs of antibiotics of five different classes changed up to 6-fold. In some cases the MIC increased, and in others it decreased. Herbicide concentrations needed to invoke the maximal response were above current food maximum residue levels but within application levels for all herbicides. Compounds that could cause induction had additive effects in combination. The role of soxS, an inducer of the AcrAB efflux pump, was tested in β-galactosidase assays with soxS-lacZ fusion strains of E. coli. Dicamba was a moderate inducer of the sox regulon. Growth assays with Phe-Arg β-naphtylamide (PAβN), an efflux pump inhibitor, confirmed a significant role of efflux in the increased tolerance of E. coli to chloramphenicol in the presence of dicamba and to kanamycin in the presence of glyphosate. Pathways of exposure with relevance to the health of humans, domestic animals, and critical insects are discussed. Increasingly common chemicals used in agriculture, domestic gardens, and public places can induce a multiple-antibiotic resistance phenotype in potential pathogens. The effect occurs upon simultaneous exposure to antibiotics and is faster than the lethal effect of antibiotics. The magnitude of the

Stabilization of the Virulence Plasmid pSLT of Salmonella Typhimurium by Three Maintenance Systems and Its Evaluation by Using a New Stability Test.

PubMed

Lobato-Márquez, Damián; Molina-García, Laura; Moreno-Córdoba, Inma; García-Del Portillo, Francisco; Díaz-Orejas, Ramón

2016-01-01

Certain Salmonella enterica serovars belonging to subspecies I carry low-copy-number virulence plasmids of variable size (50-90 kb). All of these plasmids share the spv operon, which is important for systemic infection. Virulence plasmids are present at low copy numbers. Few copies reduce metabolic burden but suppose a risk of plasmid loss during bacterial division. This drawback is counterbalanced by maintenance modules that ensure plasmid stability, including partition systems and toxin-antitoxin (TA) loci. The low-copy number virulence pSLT plasmid of Salmonella enterica serovar Typhimurium encodes three auxiliary maintenance systems: one partition system ( parAB ) and two TA systems ( ccdAB ST and vapBC2 ST ). The TA module ccdAB ST has previously been shown to contribute to pSLT plasmid stability and vapBC2 ST to bacterial virulence. Here we describe a novel assay to measure plasmid stability based on the selection of plasmid-free cells following elimination of plasmid-containing cells by ParE toxin, a DNA gyrase inhibitor. Using this new maintenance assay we confirmed a crucial role of parAB in pSLT maintenance. We also showed that vapBC2 ST , in addition to contribute to bacterial virulence, is important for plasmid stability. We have previously shown that ccdAB ST encodes an inactive CcdB ST toxin. Using our new stability assay we monitored the contribution to plasmid stability of a ccdAB ST variant containing a single mutation (R99W) that restores the toxicity of CcdB ST . The "activation" of CcdB ST (R99W) did not increase pSLT stability by ccdAB ST . In contrast, ccdAB ST behaves as a canonical type II TA system in terms of transcriptional regulation. Of interest, ccdAB ST was shown to control the expression of a polycistronic operon in the pSLT plasmid. Collectively, these results show that the contribution of the CcdB ST toxin to pSLT plasmid stability may depend on its role as a co-repressor in coordination with CcdA ST antitoxin more than on its

Serovar distribution of a DNA sequence involved in the antigenic relationship between Leptospira and equine cornea

PubMed Central

Lucchesi, Paula MA; Parma, Alberto E; Arroyo, Guillermo H

2002-01-01

Background Horses infected with Leptospira present several clinical disorders, one of them being recurrent uveitis. A common endpoint of equine recurrent uveitis is blindness. Serovar pomona has often been incriminated, although others have also been reported. An antigenic relationship between this bacterium and equine cornea has been described in previous studies. A leptospiral DNA fragment that encodes cross-reacting epitopes was previously cloned and expressed in Escherichia coli. Results A region of that DNA fragment was subcloned and sequenced. Samples of leptospiral DNA from several sources were analysed by PCR with two primer pairs designed to amplify that region. Reference strains from serovars canicola, icterohaemorrhagiae, pomona, pyrogenes, wolffi, bataviae, sentot, hebdomadis and hardjo rendered products of the expected sizes with both pairs of primers. The specific DNA region was also amplified from isolates from Argentina belonging to serogroups Canicola and Pomona. Both L. biflexa serovar patoc and L. borgpetersenii serovar tarassovi rendered a negative result. Conclusions The DNA sequence related to the antigen mimicry with equine cornea was not exclusively found in serovar pomona as it was also detected in several strains of Leptospira belonging to different serovars. The results obtained with L. biflexa serovar patoc strain Patoc I and L. borgpetersenii serovar tarassovi strain Perepelicin suggest that this sequence is not present in these strains, which belong to different genomospecies than those which gave positive results. This is an interesting finding since L. biflexa comprises nonpathogenic strains and serovar tarassovi has not been associated clinically with equine uveitis. PMID:11869455

Salmonella Modulates Metabolism During Growth under Conditions that Induce Expression of Virulence Genes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Young-Mo; Schmidt, Brian; Kidwai, Afshan S.

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative pathogen that uses complex mechanisms to invade and proliferate within mammalian host cells. To investigate possible contributions of metabolic processes in S. Typhimurium grown under conditions known to induce expression of virulence genes, we used a metabolomics-driven systems biology approach coupled with genome scale modeling. First, we identified distinct metabolite profiles associated with bacteria grown in either rich or virulence-inducing media and report the most comprehensive coverage of the S. Typhimurium metabolome to date. Second, we applied an omics-informed genome scale modeling analysis of the functional consequences of adaptive alterations inmore » S. Typhimurium metabolism during growth under our conditions. Excitingly, we observed possible sequestration of metabolites recently suggested to have immune modulating roles. Modeling efforts highlighted a decreased cellular capability to both produce and utilize intracellular amino acids during stationary phase culture in virulence conditions, despite significant abundance increases for these molecules as observed by our metabolomics measurements. Model-guided analysis suggested that alterations in metabolism prioritized other activities necessary for pathogenesis instead, such as lipopolysaccharide biosynthesis.« less

The SdiA-Regulated Gene srgE Encodes a Type III Secreted Effector

PubMed Central

Habyarimana, Fabien; Sabag-Daigle, Anice

2014-01-01

Salmonella enterica serovar Typhimurium is a food-borne pathogen that causes severe gastroenteritis. The ability of Salmonella to cause disease depends on two type III secretion systems (T3SSs) encoded in two distinct Salmonella pathogenicity islands, 1 and 2 (SPI1 and SPI2, respectively). S. Typhimurium encodes a solo LuxR homolog, SdiA, which can detect the acyl-homoserine lactones (AHLs) produced by other bacteria and upregulate the rck operon and the srgE gene. SrgE is predicted to encode a protein of 488 residues with a coiled-coil domain between residues 345 and 382. In silico studies have provided conflicting predictions as to whether SrgE is a T3SS substrate. Therefore, in this work, we tested the hypothesis that SrgE is a T3SS effector by two methods, a β-lactamase activity assay and a split green fluorescent protein (GFP) complementation assay. SrgE with β-lactamase fused to residue 40, 100, 150, or 300 was indeed expressed and translocated into host cells, but SrgE with β-lactamase fused to residue 400 or 488 was not expressed, suggesting interference by the coiled-coil domain. Similarly, SrgE with GFP S11 fused to residue 300, but not to residue 488, was expressed and translocated into host cells. With both systems, translocation into host cells was dependent upon SPI2. A phylogenetic analysis indicated that srgE is found only within Salmonella enterica subspecies. It is found sporadically within both typhoidal and nontyphoidal serovars, although the SrgE protein sequences found within typhoidal serovars tend to cluster separately from those found in nontyphoidal serovars, suggesting functional diversification. PMID:24727228

Multidrug-resistant Strains of Salmonella enterica Typhimurium, United States, 1997–19981

PubMed Central

Whichard, Jean; Rossiter, Shannon; Holland, Ben; Stamey, Karen; Headrick, Marcia L.; Barrett, Timothy J.; Angulo, Frederick J.

2004-01-01

To evaluate multidrug-resistant strains of Salmonella enterica Typhimurium, including definitive type 104 (DT104) in the United States, we reviewed data from the National Antimicrobial Resistance Monitoring System (NARMS). In 1997–1998, 25% (703) of 2,767 serotyped Salmonella isolates received at NARMS were S. Typhimurium; antimicrobial susceptibility testing and phage typing were completed for 697. Fifty-eight percent (402) were resistant to >1 antimicrobial agent. Three multidrug-resistant (>5 drugs) strains accounted for 74% (296) of all resistant isolates. Ceftriaxone resistance was present in 3% (8), and nalidixic acid resistance in 1% (4), of these multidrug-resistant strains. By phage typing, 37% (259) of S. Typhimurium isolates were DT104, 30% (209) were of undefined type and 15% (103) were untypable. Fifty percent (202) of resistant (>1 drug) isolates were DT104. Multidrug-resistant S. Typhimurium isolates, particularly DT104, account for a substantial proportion of S. Typhimurium isolates; ceftriaxone resistance is exhibited by some of these strains. PMID:15200811

A Unique Capsule Locus in the Newly Designated Actinobacillus pleuropneumoniae Serovar 16 and Development of a Diagnostic PCR Assay.

PubMed

Bossé, Janine T; Li, Yanwen; Sárközi, Rita; Gottschalk, Marcelo; Angen, Øystein; Nedbalcova, Katerina; Rycroft, Andrew N; Fodor, László; Langford, Paul R

2017-03-01

Actinobacillus pleuropneumoniae causes pleuropneumonia, an economically significant lung disease of pigs. Recently, isolates of A. pleuropneumoniae that were serologically distinct from the previously characterized 15 serovars were described, and a proposal was put forward that they comprised a new serovar, serovar 16. Here we used whole-genome sequencing of the proposed serovar 16 reference strain A-85/14 to confirm the presence of a unique capsular polysaccharide biosynthetic locus. For molecular diagnostics, primers were designed from the capsule locus of strain A-85/14, and a PCR was formulated that differentiated serovar 16 isolates from all 15 known serovars and other common respiratory pathogenic/commensal bacteria of pigs. Analysis of the capsule locus of strain A-85/14 combined with the previous serological data show the existence of a sixteenth serovar-designated serovar 16-of A. pleuropneumoniae . Copyright © 2017 Bossé et al.

An association of genotypes and antimicrobial resistance patterns among Salmonella isolates from pigs and humans in Taiwan.

PubMed

Kuo, Hung-Chih; Lauderdale, Tsai-Ling; Lo, Dan-Yuan; Chen, Chiou-Lin; Chen, Pei-Chen; Liang, Shiu-Yun; Kuo, Jung-Che; Liao, Ying-Shu; Liao, Chun-Hsing; Tsao, Chi-Sen; Chiou, Chien-Shun

2014-01-01

We collected 110 Salmonella enterica isolates from sick pigs and determined their serotypes, genotypes using pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility to 12 antimicrobials and compared the data with a collection of 18,280 isolates obtained from humans. The pig isolates fell into 12 common serovars for human salmonellosis in Taiwan; S. Typhimurium, S. Choleraesuis, S. Derby, S. Livingstone, and S. Schwarzengrund were the 5 most common serovars and accounted for a total of 84% of the collection. Of the 110 isolates, 106 (96%) were multidrug resistant (MDR) and 48 (44%) had PFGE patterns found in human isolates. S. Typhimurium, S. Choleraesuis, and S. Schwarzengrund were among the most highly resistant serovars. The majority of the 3 serovars were resistant to 8-11 of the tested antimicrobials. The isolates from pigs and humans sharing a common PFGE pattern displayed identical or very similar resistance patterns and Salmonella strains that caused severe infection in pigs were also capable of causing infections in humans. The results indicate that pigs are one of the major reservoirs to human salmonellosis in Taiwan. Almost all of the pig isolates were MDR, which highlights the necessity of strictly regulating the use of antimicrobials in the agriculture sector in Taiwan.

Generation and selection of anti-flagellin monoclonal antibodies useful for serotyping Salmonella enterica.

PubMed

Hiriart, Yanina; Serradell, Maria; Martínez, Araci; Sampaolesi, Sofia; Maciel, Dolores Gonzalez; Chabalgoity, Jose Alejandro; Yim, Lucía; Algorta, Gabriela; Rumbo, Martin

2013-01-01

In developing countries, bacterial acute gastroenteritis continues to be an important cause of morbidity and mortality among young children. Salmonellosis constitutes a major cause of infectious enteritis worldwide, most of them associated to the consumption of contaminated food products. Traditionally, Salmonella has been classified in serovars based on varieties of O and H surface antigens. In the present work we generated and characterized a panel of anti-flagellin monoclonal antibodies (MAbs) in order to select antibodies useful for detecting the H surface antigen. Four different MAbs were obtained by somatic hybridization of splenocytes. We found two MAbs that recognised regions of flagellin conserved among different Salmonella serovars. Other two MAbs recognised structures restricted to Salmonella enterica sv. Typhimurium, being one of them suitable for agglutination tests. Using a diverse panel of S. enterica serovars with different H antigen varieties we confirmed that this MAb agglutinates specifically S. Typhimurium (antigenic formula: 4,12:i:1,2) or other serovars expressing flagellar factor i. In conclusion, we generated a valuable immunochemical tool to be used in simple assays for serotyping of epidemiologically relevant strains. The capacity to characterize specific strains and determine the primary sources of Salmonella contamination generate valuable information of the epidemiology of this microorganism, contributing to the improvement of public health.

Genome Sequence of Lactobacillus salivarius NIAS840, Isolated from Chicken Intestine

PubMed Central

Ham, Jun-Sang; Kim, Hyoun-Wook; Seol, Kuk-Hwan; Jang, Aera; Jeong, Seok-Geun; Oh, Mi-Hwa; Kim, Dong-Hun; Kang, Dae-Kyung; Kim, Geun-Bae; Cha, Chang-Jun

2011-01-01

Lactobacillus salivarius is a well-known lactic acid bacterium to which increasing attention has been paid recently for use as probiotics for humans and animals. L. salivarius NIAS840 was first isolated from broiler chicken feces, displaying antimicrobial activities against multidrug-resistant Staphylococcus aureus and Salmonella enterica serovar Typhimurium. Here, we report the genome sequence of L. salivarius NIAS840 (2,046,557 bp) including a small plasmid and two megaplasmids. PMID:21914873

Six new leptospiral serovars isolated from wild animals in Peru.

PubMed Central

Liceras de Hidalgo, J L; Sulzer, K R

1984-01-01

Six new serovars of Leptospira interrogans were isolated from opossums (Didelphis marsupialis and Philander opossum) trapped in the Peruvian jungle. The proposed names, type strain designation, and serogroup of the serovars, respectively, were: huallaga, strain M-7, Djasiman serogroup; luis, strain M-6, Tarassovi serogroup; machiguenga, strain MMD-3, Icterohaemorrhagiae serogroup; rioja, strain MR-12, Bataviae serogroup; rupa rupa, strain M-3, Sejroe serogroup; and tingomaria, strain M-13, Cynopteri serogroup. PMID:6470106

β-glucans from Coriolus versicolor protect mice against S. typhimurium challenge by activation of macrophages.

PubMed

Shi, Shao-Hua; Yang, Wen-Tao; Huang, Ke-Yan; Jiang, Yan-Long; Yang, Gui-Lian; Wang, Chun-Feng; Li, Yu

2016-05-01

The effects of β-glucans from Coriolus versicolor (CVP), which are extracted from a well-known immune stimulator C. versicolor, have been demonstrated extensively in vitro and in vivo. However, until now, the phagocytic activity has not been elucidated. Hence, the objective of the present study was to identify the antibacterial activity of CVP or CVP-treated macrophages by an analysis of cell cytotoxicity, phagocytic activity, intracellular bacterial survival, macrophage activation, production of nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS) in CVP-treated macrophages using flow cytometry, RT-PCR, a gentamicin protection assay, a Nitric oxide assay and an iNOS enzymatic activity assay. The results indicate that CVP-treated macrophages can phagocytize and kill bacteria, probably due to the production of NO and iNOS. More importantly, CVP-treated macrophages are effective at protecting mice against the challenge of Salmonella typhimurium. The results of this study suggest that the antibacterial effects of CVP are probably caused by the activation of innate immune cells, especially macrophages, because the activated macrophage produces NO, which kills bacteria. These phenomena indicate the possibility of CVP as a potential alternative for antibiotics against resistant bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Genomic comparison of the closely-related Salmonella enterica serovars enteritidis, dublin and gallinarum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, T. David; Schmieder, Robert; Silva, Genivaldo G. Z.

The Salmonella enterica serovars Enteritidis, Dublin, and Gallinarum are closely related but differ in virulence and host range. To identify the genetic elements responsible for these differences and to better understand how these serovars are evolving, we sequenced the genomes of Enteritidis strain LK5 and Dublin strain SARB12 and compared these genomes to the publicly available Enteritidis P125109, Dublin CT 02021853 and Dublin SD3246 genome sequences. We also compared the publicly available Gallinarum genome sequences from biotype Gallinarum 287/91 and Pullorum RKS5078. Using bioinformatic approaches, we identified single nucleotide polymorphisms, insertions, deletions, and differences in prophage and pseudogene content betweenmore » strains belonging to the same serovar. Through our analysis we also identified several prophage cargo genes and pseudogenes that affect virulence and may contribute to a host-specific, systemic lifestyle. These results strongly argue that the Enteritidis, Dublin and Gallinarum serovars of Salmonella enterica evolve by acquiring new genes through horizontal gene transfer, followed by the formation of pseudogenes. As a result, the loss of genes necessary for a gastrointestinal lifestyle ultimately leads to a systemic lifestyle and niche exclusion in the host-specific serovars.« less

Genomic comparison of the closely-related Salmonella enterica serovars enteritidis, dublin and gallinarum

DOE PAGES

Matthews, T. David; Schmieder, Robert; Silva, Genivaldo G. Z.; ...

2015-06-03

The Salmonella enterica serovars Enteritidis, Dublin, and Gallinarum are closely related but differ in virulence and host range. To identify the genetic elements responsible for these differences and to better understand how these serovars are evolving, we sequenced the genomes of Enteritidis strain LK5 and Dublin strain SARB12 and compared these genomes to the publicly available Enteritidis P125109, Dublin CT 02021853 and Dublin SD3246 genome sequences. We also compared the publicly available Gallinarum genome sequences from biotype Gallinarum 287/91 and Pullorum RKS5078. Using bioinformatic approaches, we identified single nucleotide polymorphisms, insertions, deletions, and differences in prophage and pseudogene content betweenmore » strains belonging to the same serovar. Through our analysis we also identified several prophage cargo genes and pseudogenes that affect virulence and may contribute to a host-specific, systemic lifestyle. These results strongly argue that the Enteritidis, Dublin and Gallinarum serovars of Salmonella enterica evolve by acquiring new genes through horizontal gene transfer, followed by the formation of pseudogenes. As a result, the loss of genes necessary for a gastrointestinal lifestyle ultimately leads to a systemic lifestyle and niche exclusion in the host-specific serovars.« less

Genomic Comparison of the Closely-Related Salmonella enterica Serovars Enteritidis, Dublin and Gallinarum

PubMed Central

Matthews, T. David; Schmieder, Robert; Silva, Genivaldo G. Z.; Busch, Julia; Cassman, Noriko; Dutilh, Bas E.; Green, Dawn; Matlock, Brian; Heffernan, Brian; Olsen, Gary J.; Farris Hanna, Leigh; Schifferli, Dieter M.; Maloy, Stanley; Dinsdale, Elizabeth A.; Edwards, Robert A.

2015-01-01

The Salmonella enterica serovars Enteritidis, Dublin, and Gallinarum are closely related but differ in virulence and host range. To identify the genetic elements responsible for these differences and to better understand how these serovars are evolving, we sequenced the genomes of Enteritidis strain LK5 and Dublin strain SARB12 and compared these genomes to the publicly available Enteritidis P125109, Dublin CT 02021853 and Dublin SD3246 genome sequences. We also compared the publicly available Gallinarum genome sequences from biotype Gallinarum 287/91 and Pullorum RKS5078. Using bioinformatic approaches, we identified single nucleotide polymorphisms, insertions, deletions, and differences in prophage and pseudogene content between strains belonging to the same serovar. Through our analysis we also identified several prophage cargo genes and pseudogenes that affect virulence and may contribute to a host-specific, systemic lifestyle. These results strongly argue that the Enteritidis, Dublin and Gallinarum serovars of Salmonella enterica evolve by acquiring new genes through horizontal gene transfer, followed by the formation of pseudogenes. The loss of genes necessary for a gastrointestinal lifestyle ultimately leads to a systemic lifestyle and niche exclusion in the host-specific serovars. PMID:26039056

Porcine response to a multidrug-resistant Salmonella enterica serovar I 4,[5],12:i:- outbreak isolate

USDA-ARS?s Scientific Manuscript database

Salmonella enterica serovar I 4,[5],12:i:- has emerged as a common nontyphoidal Salmonella serovar to cause human foodborne illness. An interesting trait of serovar I 4,[5],12:i:- is it only expresses the fliC gene for bacterial motility (i.e. monophasic), while most Salmonella strains alternately e...

Repression of Salmonella enterica phoP Expression by Small Molecules from Physiological Bile

PubMed Central

Antunes, L. Caetano M.; Wang, Melody; Andersen, Sarah K.; Ferreira, Rosana B. R.; Kappelhoff, Reinhild; Han, Jun; Borchers, Christoph H.

2012-01-01

Infection with Salmonella enterica serovar Typhi in humans causes the life-threatening disease typhoid fever. In the laboratory, typhoid fever can be modeled through the inoculation of susceptible mice with Salmonella enterica serovar Typhimurium. Using this murine model, we previously characterized the interactions between Salmonella Typhimurium and host cells in the gallbladder and showed that this pathogen can successfully invade gallbladder epithelial cells and proliferate. Additionally, we showed that Salmonella Typhimurium can use bile phospholipids to grow at high rates. These abilities are likely important for quick colonization of the gallbladder during typhoid fever and further pathogen dissemination through fecal shedding. To further characterize the interactions between Salmonella and the gallbladder environment, we compared the transcriptomes of Salmonella cultures grown in LB broth or physiological murine bile. Our data showed that many genes involved in bacterial central metabolism are affected by bile, with the citric acid cycle being repressed and alternative respiratory systems being activated. Additionally, our study revealed a new aspect of Salmonella interactions with bile through the identification of the global regulator phoP as a bile-responsive gene. Repression of phoP expression could also be achieved using physiological, but not commercial, bovine bile. The biological activity does not involve PhoPQ sensing of a bile component and is not caused by bile acids, the most abundant organic components of bile. Bioactivity-guided purification allowed the identification of a subset of small molecules from bile that can elicit full activity; however, a single compound with phoP inhibitory activity could not be isolated, suggesting that multiple molecules may act in synergy to achieve this effect. Due to the critical role of phoP in Salmonella virulence, further studies in this area will likely reveal aspects of the interaction between Salmonella

Escherichia coli O157:H7 induces stronger plant immunity than Salmonella enterica Typhimurium SL1344.

PubMed

Roy, Debanjana; Panchal, Shweta; Rosa, Bruce A; Melotto, Maeli

2013-04-01

Consumption of fresh produce contaminated with bacterial human pathogens has resulted in various, sometimes deadly, disease outbreaks. In this study, we assessed plant defense responses induced by the fully pathogenic bacteria Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium SL1344 in both Arabidopsis thaliana and lettuce (Lactuca sativa). Unlike SL1344, O157:H7 induced strong plant immunity at both pre-invasion and post-invasion steps of infection. For instance, O157:H7 triggered stomatal closure even under high relative humidity, an environmental condition that generally weakens plant defenses against bacteria in the field and laboratory conditions. SL1344 instead induced a transient stomatal immunity. We also observed that PR1 gene expression was significantly higher in Arabidopsis leaves infected with O157:H7 compared with SL1344. These results suggest that plants may recognize and respond to some human pathogens more effectively than others. Furthermore, stomatal immunity can diminish the penetration of human pathogens through the leaf epidermis, resulting in low bacterial titers in the plant apoplast and suggesting that additional control measures can be employed to prevent food contamination. The understanding of how plant responses can diminish bacterial contamination is paramount in preventing outbreaks and improving the safety of food supplies.

Salmonella Typhimurium Enzymatically Landscapes the Host Intestinal Epithelial Cell (IEC) Surface Glycome to Increase Invasion*

PubMed Central

Park, Dayoung; Arabyan, Narine; Williams, Cynthia C.; Song, Ting; Mitra, Anupam; Weimer, Bart C.; Lebrilla, Carlito B.

2016-01-01

Although gut host-pathogen interactions are glycan-mediated processes, few details are known about the participating structures. Here we employ high-resolution mass spectrometric profiling to comprehensively identify and quantitatively measure the exact modifications of native intestinal epithelial cell surface N-glycans induced by S. typhimurium infection. Sixty minutes postinfection, select sialylated structures showed decreases in terms of total number and abundances. To assess the effect of cell surface mannosylation, we selectively rerouted glycan expression on the host using the alpha-mannosidase inhibitor, kifunensine, toward overexpression of high mannose. Under these conditions, internalization of S. typhimurium significantly increased, demonstrating that bacteria show preference for particular structures. Finally, we developed a novel assay to measure membrane glycoprotein turnover rates, which revealed that glycan modifications occur by bacterial enzyme activity rather than by host-derived restructuring strategies. This study is the first to provide precise structural information on how host N-glycans are altered to support S. typhimurium invasion. PMID:27754876

Gold nanoparticle-based enzyme-linked antibody-aptamer sandwich assay for detection of Salmonella Typhimurium.

PubMed

Wu, Wenhe; Li, Jun; Pan, Dun; Li, Jiang; Song, Shiping; Rong, Mingge; Li, Zixi; Gao, Jimin; Lu, Jianxin

2014-10-08

Enzyme-linked immunosorbent assay (ELISA) provides a convenient means for the detection of Salmonella enterica serovar Typhimurium (STM), which is important for rapid diagnosis of foodborne pathogens. However, conventional ELISA is limited by antibody-antigen immunoreactions and suffers from poor sensitivity and tedious sample pretreatment. Therefore, development of novel ELISA remains challenging. Herein, we designed a comprehensive strategy for rapid, sensitive, and quantitative detection of STM with high specificity by gold nanoparticle-based enzyme-linked antibody-aptamer sandwich (nano-ELAAS) method. STM was captured and preconcentrated from samples with aptamer-modified magnetic particles, followed by binding with detector antibodies. Then nanoprobes carrying a large amount of reporter antibodies and horseradish peroxidase molecules were used for colorimetric signal amplification. Under the optimized reaction conditions, the nano-ELAAS assay had a quantitative detection range from 1 × 10(3) to 1 × 10(8) CFU mL(-1), a limit of detection of 1 × 10(3) CFU mL(-1), and a selectivity of >10-fold for STM in samples containing other bacteria at higher concentration with an assay time less than 3 h. In addition, the developed nanoprobes were improved in terms of detection range and/or sensitivity when compared with two commercial enzyme-labeled antibody signal reporters. Finally, the nano-ELAAS method was demonstrated to work well in milk samples, a common source of STM contamination.

Influence of water activity on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in peanut butter by microwave heating.

PubMed

Song, Won-Jae; Kang, Dong-Hyun

2016-12-01

This study evaluated the efficacy of a 915 MHz microwave with 3 different electric power levels to inactivate three pathogens in peanut butter with different aw. Peanut butter inoculated with Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium and Listeria monocytogenes (0.3, 0.4, and 0.5 aw) were treated with a 915 MHz microwave with 2, 4, and 6 kW for up to 5 min. Six kW 915 MHz microwave treatment for 5 min reduced these three pathogens by 1.97 to >5.17 log CFU/g. Four kW 915 MHz microwave processing for 5 min reduced these pathogens by 0.41-1.98 log CFU/g. Two kW microwave heating did not inactivate pathogens in peanut butter. Weibull and Log-Linear + Shoulder models were used to describe the survival curves of three pathogens because they exhibited shouldering behavior. Td and T5d values were calculated based on the Weibull and Log-Linear + Shoulder models. Td values of the three pathogens were similar to D-values of Salmonella subjected to conventional heating at 90 °C but T5d values were much shorter than those of conventional heating at 90 °C. Generally, increased aw resulted in shorter T5d values of pathogens, but not shorter Td values. The results of this study can be used to optimize microwave heating pasteurization system of peanut butter. Copyright © 2016. Published by Elsevier Ltd.

Salmonella Intracellular Lifestyles and Their Impact on Host-to-Host Transmission.

PubMed

Pucciarelli, M Graciela; García-Del Portillo, Francisco

2017-07-01

More than a century ago, infections by Salmonella were already associated with foodborne enteric diseases with high morbidity in humans and cattle. Intestinal inflammation and diarrhea are hallmarks of infections caused by nontyphoidal Salmonella serovars, and these pathologies facilitate pathogen transmission to the environment. In those early times, physicians and microbiologists also realized that typhoid and paratyphoid fever caused by some Salmonella serovars could be transmitted by "carriers," individuals outwardly healthy or at most suffering from some minor chronic complaint. In his pioneering study of the nontyphoidal serovar Typhimurium in 1967, Takeuchi published the first images of intracellular bacteria enclosed by membrane-bound vacuoles in the initial stages of the intestinal epithelium penetration. These compartments, called Salmonella -containing vacuoles, are highly dynamic phagosomes with differing biogenesis depending on the host cell type. Single-cell studies involving real-time imaging and gene expression profiling, together with new approaches based on genetic reporters sensitive to growth rate, have uncovered unprecedented heterogeneous responses in intracellular bacteria. Subpopulations of intracellular bacteria displaying fast, reduced, or no growth, as well as cytosolic and intravacuolar bacteria, have been reported in both in vitro and in vivo infection models. Recent investigations, most of them focused on the serovar Typhimurium, point to the selection of persisting bacteria inside macrophages or following an autophagy attack in fibroblasts. Here, we discuss these heterogeneous intracellular lifestyles and speculate on how these disparate behaviors may impact host-to-host transmissibility of Salmonella serovars.

Antibody response to experimental Salmonella typhimurium infection in chickens measured by ELISA.

PubMed

Hassan, J O; Barrow, P A; Mockett, A P; Mcleod, S

1990-05-26

An indirect ELISA has been developed to detect Salmonella typhimurium antibodies in chicken sera, using whole bacterial cell protein, flagellar protein or lipopolysaccharide as antigens. In experimental infections high concentrations of S typhimurium-specific IgG persisted after the faecal excretion of S typhimurium had ceased, whereas the specific IgM response was transitory. Some uninfected chickens placed in contact with experimentally infected birds developed high IgG titres in the absence of detectable faecal excretion. Other S typhimurium strains, which varied in their invasive abilities, also induced high titres of IgG. The ELISA allowed chickens infected experimentally with S typhimurium to be differentiated from chickens infected with 10 other serotypes, including S enteritidis. The use of whole blood in place of serum in the ELISA reduced the titres slightly. The storage of serum dried on to filter paper strips for four weeks produced little change in ELISA antibody titre, and the treatment of such strips with phenol or chloroform vapour had little or no effect on the antibody titre.

Conjugal Transfer of the Pathogenicity Island ROD21 in Salmonella enterica serovar Enteritidis Depends on Environmental Conditions

PubMed Central

Salazar-Echegarai, Francisco J.; Tobar, Hugo E.; Nieto, Pamela A.; Riedel, Claudia A.; Bueno, Susan M.

2014-01-01

Unstable pathogenicity islands are chromosomal elements that can be transferred from one bacterium to another. Salmonella enterica serovar Enteritidis (S. Enteritidis) is a pathogenic bacterium containing such unstable pathogenicity islands. One of them, denominated ROD21, is 26.5 kb in size and capable of excising from the chromosome in certain culture conditions, as well as during bacterial infection of phagocytic cells. In this study we have evaluated whether ROD21 can be effectively transferred from one bacterium to another. We generated a donor and several recipient strains of S. Enteritidis to carry out transfer assays in liquid LB medium. These assays showed that ROD21 is effectively transferred from donor to recipient strains of S. Enteritidis and S. Typhimurium. When Escherichia coli was used as the recipient strain, ROD21 transfer failed to be observed. Subsequently, we showed that a conjugative process was required for the transfer of the island and that changes in temperature and pH increased the transfer frequency between Salmonella strains. Our data indicate that ROD21 is an unstable pathogenicity island that can be transferred by conjugation in a species-specific manner between Salmonellae. Further, ROD21 transfer frequency increases in response to environmental changes, such as pH and temperature. PMID:24705125

Prevalence of Salmonella spp., and serovars isolated from captive exotic reptiles in New Zealand.

PubMed

Kikillus, K H; Gartrell, B D; Motion, E

2011-07-01

To investigate the prevalence of Salmonella spp. in captive exotic reptile species in New Zealand, and identify the serovars isolated from this population. Cloacal swabs were obtained from 378 captive exotic reptiles, representing 24 species, residing in 25 collections throughout New Zealand between 2008 and 2009. Samples were cultured for Salmonella spp., and suspected colonies were serotyped by the Institute of Environmental Science and Research (ESR). Forty-three of the 378 (11.4%) reptiles sampled tested positive for Salmonella spp., with 95% CI for the estimated true prevalence being 12-25% in exotic reptiles in this study population. Lizards tested positive for Salmonella spp. more often than chelonians. Agamid lizards tested positive more often than any other family group, with 95% CI for the estimated true prevalence being 56-100%.. Six Salmonella serovars from subspecies I and two from subspecies II were isolated. The serovar most commonly isolated was S. Onderstepoort (30.2%), followed by S. Thompson (20.9%), S. Potsdam (14%), S. Wangata (14%), S. Infantis (11.6%) and S. Eastbourne (2.3%). All of the subspecies I serovars have been previously reported in both reptiles and humans in New Zealand, and include serovars previously associated with disease in humans. This study showed that Salmonella spp. were commonly carried by exotic reptiles in the study population in New Zealand. Several serovars of Salmonella spp. with known pathogenicity to humans were isolated, including S. Infantis, which is one of the most common serovars isolated from both humans and non-human sources in New Zealand. The limitations of this study included the bias engendered by the need for voluntary involvement in the study, and the non-random sampling design. Based on the serovars identified in this and previous studies, it is recommended native and exotic reptiles be segregated within collections, especially when native reptiles may be used for biodiversity restoration

Isolation and characterization of Salmonella enterica in day-old ducklings in Egypt

PubMed Central

Osman, Kamelia M; Marouf, Sherif H; Zolnikov, Tara R; AlAtfeehy, Nayerah

2014-01-01

Importing day-old ducklings (DOD) unknowingly infected with non-typhoid Salmonella (NTS) may be associated with disease risk. Domestic and international trade may enhance this risk. Salmonella enterica serovars, their virulence genes combinations and antibiotic resistance, garner attention for their potentiality to contribute to the adverse health effects on populations throughout the world. The aim of this study was to estimate the risk of imported versus domestic DOD as potential carriers of NTS. The results confirm the prevalence of salmonellosis in imported ducklings was 18.5% (25/135), whereas only 12% (9/75) of cases were determined in the domestic ducklings. Fourteen serovars (Salmonella enteritidis, Salmonella kisii, Salmonella typhimurium, Salmonella gaillac, Salmonella uno, Salmonella eingedi, Salmonella shubra, Salmonella bardo, Salmonella inganda, Salmonella kentucky, Salmonella stanley, Salmonella virchow, Salmonella haifa, and Salmonella anatum) were isolated from the imported ducklings, whereas only S. enteritidis, S. typhimurium, S. virchow, and S. shubra were isolated from the domestic ducklings. The isolated Salmonella serovars were 100% susceptible to only colistin sulphate and 100% resistant to lincomycin. The 14 Salmonella serovars were screened for 11 virulence genes (invA, avrA, ssaQ, mgtC, siiD, sopB, gipA, sodC1, sopE1, spvC, and bcfC) by PCR. The invA, sopB, and bcfC genes were detected in 100% of the Salmonella serovars; alternatively, the gipA gene was absent in all of the isolated Salmonella serovars. The 11 virulent genes were not detected in either of S. stanley or S. haifa serovars. The results confirm an association between antibiotic resistance and virulence of Salmonella in the DOD. This study confirms the need for a country adherence to strict public health and food safety regimes. PMID:24548159

Antimicrobial potential of cauliflower, broccoli, and okara byproducts against foodborne bacteria.

PubMed

Sanz-Puig, Maria; Pina-Pérez, Maria C; Criado, Maria Nieves; Rodrigo, Dolores; Martínez-López, Antonio

2015-01-01

The antimicrobial potential of cauliflower, broccoli, and okara byproducts was assessed against Gram-positive and Gram-negative bacteria. Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, Bacillus cereus, and Listeria monocytogenes serovar 4b growth behavior was assessed under exposure to 5% vegetable byproducts added to the reference medium, buffered peptone water (0.1% [wt/vol]), at 37°C. Although the byproducts were not effective against L. monocytogenes, they were bactericidal against Salmonella Typhimurium, E. coli O157:H7, and B. cereus. The most promising results were achieved with the cauliflower-Salmonella Typhimurium combination, because the bacterial population was reduced by 3.11 log10 cycles after 10 h of incubation at 37°C as a result of 5% cauliflower addition. Further studies were carried out for this combination, at different cauliflower concentrations (0, 0.5, 1, 5, 10, and 15%) and at temperatures in the range of 5-37°C. The greatest inactivation level (6.11 log10 cycles) was achieved at refrigeration temperature (5°C) using 15% cauliflower addition. Both temperature and cauliflower concentration significantly (p≤0.05) influenced the Salmonella Typhimurium inactivation level. The kinetic parameters were adjusted to mathematical models. The modified Gompertz mathematical model provided an accurate fit (root-mean-square error (RMSE) [0.00009-0.21] and adjusted-R(2) [0.81-0.99]) to experimental Salmonella Typhimurium survival curves describing inactivation kinetics of the pathogen to the antimicrobial effect of cauliflower byproduct.

Curli Fibers Are Highly Conserved between Salmonella typhimurium and Escherichia coli with Respect to Operon Structure and Regulation

PubMed Central

Römling, Ute; Bian, Zhao; Hammar, Mårten; Sierralta, Walter D.; Normark, Staffan

1998-01-01

Mouse-virulent Salmonella typhimurium strains SR-11 and ATCC 14028-1s express curli fibers, thin aggregative fibers, at ambient temperature on plates as judged by Western blot analysis and electron microscopy. Concomitantly with curli expression, cells develop a rough and dry colony morphology and bind the dye Congo red (called the rdar morphotype). Cloning and characterization of the two divergently transcribed operons required for curli biogenesis, csgBA(C) and csgDEFG, from S. typhimurium SR-11 revealed the same gene order and flanking genes as in Escherichia coli. The divergence of the curli region between S. typhimurium and E. coli at the nucleotide level is above average (22.4%). However, a high level of conservation at the protein level, which ranged from 86% amino acid homology for the fiber subunit CsgA to 99% homology for the lipoprotein CsgG, implies functional constraints on the gene products. Consequently, S. typhimurium genes on low-copy-number plasmids were able to complement respective E. coli mutants, although not always to wild-type levels. rpoS and ompR are required for transcriptional activation of (at least) the csgD promoter. The high degree of conservation at the protein level and the identical regulation patterns in E. coli and S. typhimurium suggest similar roles of curli fibers in the same ecological niche in the two species. PMID:9457880

Metabolic parameters linked by Phenotype MicroArray to acid resistance profiles of poultry-associated Salmonella enterica.

USDA-ARS?s Scientific Manuscript database

Phenotype microarrays were analyzed for 51 datasets derived from Salmonella enterica. The top 4 serovars associated with poultry products and one associated with turkey, respectively Typhimurium, Enteritidis, Heidelberg, Infantis and Senftenberg, were represented. Datasets were clustered into two ...

Label-free SERS detection of Salmonella Typhimurium on DNA aptamer modified AgNR substrates

USDA-ARS?s Scientific Manuscript database

A straightforward label-free method based on aptamer binding and surface enhanced Raman specstroscopy (SERS) has been developed for the detection of Salmonella Typhimurium, an important foodborne pathogen that causes gastroenteritis in both humans and animals. Surface of the SERS-active silver nanor...

Virulence of Serovar C-1 Strains of Avibacterium paragallinarum.

PubMed

Trujillo-Ruíz, H H; Shivaprasad, H L; Morales-Erasto, V; Talavera-Rojas, M; Salgado-Miranda, C; Salazar-García, F; Blackall, P J; Soriano-Vargas, E

2016-12-01

The bacterium Avibacterium paragallinarum is the etiologic agent of infectious coryza of chickens. There are nine serovars of A. paragallinarum , and serovar C-1 has emerged in outbreaks of infectious coryza in layer hens in the Americas, with all isolates having been obtained from infectious coryza-vaccinated chickens. In the current study, the clinical and histopathologic outcomes of experimental infections in chickens with A. paragallinarum of serovar C-1 were investigated. The Japanese serovar reference strain, H-18, and a Mexican isolate, ESV-135, were included in the study. No differences in clinical sign scores or morbidity were observed between the two strains. The two bacterial strains caused microscopic lesions of lymphoplasmacytic inflammation in the mucosa of the nasal cavity, infraorbital sinus, and trachea. Similar severe lesions were observed in birds inoculated with both H-18 and ESV-135 strains. The lesions were present 48 hr after inoculation and persisted until day 10 after inoculation. Slight to severe, extensive hemorrhages were observed in the lumen, mucous membranes, and lamina propria of the nasal cavity and infraorbital sinus in most of the chickens inoculated with either the reference strain H-18 or the ESV-135 isolate. Hemorrhages in the upper respiratory tract of chickens experimentally infected with A. paragallinarum are reported here for the first time. The results have confirmed the high virulence of the reference strain H-18 as previously reported and have shown that the Mexican isolate was as virulent as the reference strain. The virulence of A. paragallinarum isolates may play a role in explaining why severe infectious coryza outbreaks are being seen in both vaccinated and nonvaccinated chicken flocks.

Evaluation of immunogenicity and protective efficacy of adjuvanted Salmonella Typhimurium ghost vaccine against salmonellosis in chickens.