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Sample records for aeruginosa salmonella typhimurium

  1. Evaluation of copper ion of antibacterial effect on Pseudomonas aeruginosa, Salmonella typhimurium and Helicobacter pylori and optical, mechanical properties

    NASA Astrophysics Data System (ADS)

    Kim, Young-Hwan; Choi, Yu-ri; Kim, Kwang-Mahn; Choi, Se-Young

    2012-02-01

    Antibacterial effect on Pseudomonas aeruginosa, Salmonella typhimurium and Helicobacter pylori of copper ion was researched. Also, additional effects of copper ion coating on optical and mechanical properties were researched as well. Copper ion was coated on glass substrate as a thin film to prevent bacteria from growing. Cupric nitrate was used as precursors for copper ion. The copper ion contained sol was deposited by spin coating process on glass substrate. Then, the deposited substrates were heat treated at the temperature range between 200 °C and 250 °C. The thickness of deposited copper layer on the surface was 63 nm. The antibacterial effect of copper ion coated glass on P. aeruginosa, S. typhimurium and H. pylori demonstrated excellent effect compared with parent glass. Copper ion contained layer on glass showed a similar value of transmittance compared with value of parent glass. The 3-point bending strength and Vickers hardness were 209.2 MPa, 540.9 kg/mm2 which were about 1.5% and 1.3% higher than the value of parent glass. From these findings, it is clear that copper ion coating on glass substrate showed outstanding effect not only in antibacterial activity but also in optical and mechanical properties as well.

  2. The emerging periplasm-localized subclass of AroQ chorismate mutases, exemplified by those from Salmonella typhimurium and Pseudomonas aeruginosa

    PubMed Central

    Calhoun, David H; Bonner, Carol A; Gu, Wei; Xie, Gary; Jensen, Roy A

    2001-01-01

    Background Chorismate mutases of the AroQ homology class are widespread in the Bacteria and the Archaea. Many of these exist as domains that are fused with other aromatic-pathway catalytic domains. Among the monofunctional AroQ proteins, that from Erwinia herbicola was previously shown to have a cleavable signal peptide and located in the periplasmic compartment. Whether or not this might be unique to E. herbicola was unknown. Results The gene coding for the AroQ protein was cloned from Salmonella typhimurium, and the AroQ protein purified from both S. typhimurium and Pseudomonas aeruginosa was shown to have a periplasmic location. The periplasmic chorismate mutases (denoted *AroQ) are shown to be a distinct subclass of AroQ, being about twice the size of cytoplasmic AroQ proteins. The increased size is due to a carboxy-terminal extension of unknown function. In addition, a so-far novel aromatic aminotransferase was shown to be present in the periplasm of P. aeruginosa. Conclusions Our analysis has detected a number of additional *aroQ genes. The joint presence of *AroQ, cyclohexadienyl dehydratase and aromatic aminotransferase in the periplasmic compartment of P. aeruginosa comprises a complete chorismate-to-phenylalanine pathway and accounts for the "hidden overflow pathway" to phenylalanine described previously. PMID:11532214

  3. Microantiglobulin Test for Detecting Salmonella typhimurium Agglutinins

    PubMed Central

    Williams, J. E.; Whittemore, A. D.

    1972-01-01

    A sensitive antiglobulin (AG) test procedure for the demonstration and experimental study of the agglutinin response of chickens infected orally with Salmonella typhimurium is described. A tetrazolium-stained S. typhimurium antigen was employed with microagglutination techniques and equipment for the first time in conducting the AG test. Results with the conventional macroscopy tube agglutination test for S. typhimurium and the 24-hr microtest were comparable; however, the AG test enhanced titers as much as 16 times, and these persisted at a significant level for as long as 4 months. This study is being extended to other Salmonella serotypes and possible field applications of the AG test procedure. Images PMID:4113257

  4. 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.

  5. Salmonella typhimurium abscess of the chest wall

    PubMed Central

    Tonziello, Gilda; Valentinotti, Romina; Arbore, Enrico; Cassetti, Paolo; Luzzati, Roberto

    2013-01-01

    Patient: Male, 73 Final Diagnosis: Salmonella typhimurium abscess of the chest wall Symptoms: — Medication: Ciprofloxacin Clinical Procedure:— Specialty: Infectious Diseases Objective: Unusual clinical course Background: Non-typhoid Salmonella extra-intestinal infections usually develop in infants and in adult patients with pre-existing predisposing conditions. Blood stream infections and urinary tract infections are the most common clinical presentations, but other sites of infection may be involved as well. Case Report: We describe a case of invasive salmonellosis caused by Salmonella typhimurium involving the chest wall in a 73-year-old man. The patient had suffered from gastroenteritis followed by left basal pneumonia with pleural effusion 7 weeks before. The CT scan of the chest wall showed a pericostal abscess with shirt-stud morphology near the left last cartilaginous arch. The abscess was surgically drained and patient was cured after a 40-day ciprofloxacin treatment. Conclusions: A review of the literature on extra-intestinal non-typhoid salmonellosis shows that pleuropulmonary and soft-tissue infections are uncommon. We argue that non-typhoid Salmonella might be considered as a possible cause of chest wall abscess in individuals with recent history of gastroenteritis complicated by pneumonia and pleural effusion. PMID:24298305

  6. 40 CFR 79.68 - Salmonella typhimurium reverse mutation assay.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Salmonella typhimurium reverse mutation assay. 79.68 Section 79.68 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGISTRATION OF FUELS AND FUEL ADDITIVES Testing Requirements for Registration § 79.68 Salmonella typhimurium reverse...

  7. 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. PMID:27527766

  8. Study of Salmonella Typhimurium Infection in Laying Hens.

    PubMed

    Pande, Vivek V; Devon, Rebecca L; Sharma, Pardeep; McWhorter, Andrea R; Chousalkar, Kapil K

    2016-01-01

    Members of Salmonella enterica are frequently involved in egg and egg product related human food poisoning outbreaks worldwide. In Australia, Salmonella Typhimurium is frequently involved in egg and egg product related foodborne illness and Salmonella Mbandaka has also been found to be a contaminant of the layer farm environment. The ability possessed by Salmonella Enteritidis to colonize reproductive organs and contaminate developing eggs has been well-described. However, there are few studies investigating this ability for Salmonella Typhimurium. The hypothesis of this study was that the Salmonella Typhimurium can colonize the gut for a prolonged period of time and that horizontal infection through feces is the main route of egg contamination. At 14 weeks of age hens were orally infected with either S. Typhimurium PT 9 or S. Typhimurium PT 9 and Salmonella Mbandaka. Salmonella shedding in feces and eggs was monitored for 15 weeks post-infection. Egg shell surface and internal contents of eggs laid by infected hens were cultured independently for detection of Salmonella spp. The mean Salmonella load in feces ranged from 1.54 to 63.35 and 0.31 to 98.38 most probable number/g (MPN/g) in the S. Typhimurium and S. Typhimurium + S. Mbandaka group, respectively. No correlation was found between mean fecal Salmonella load and frequency of egg shell contamination. Egg shell contamination was higher in S. Typhimurium + S. Mbandaka infected group (7.2% S. Typhimurium, 14.1% S. Mbandaka) compared to birds infected with S. Typhimurium (5.66%) however, co-infection had no significant impact on egg contamination by S. Typhimurium. Throughout the study Salmonella was not recovered from internal contents of eggs laid by hens. Salmonella was isolated from different segments of oviduct of hens from both the groups, however pathology was not observed on microscopic examination. This study investigated Salmonella shedding for up to 15 weeks p.i which is a longer period of time

  9. Study of Salmonella Typhimurium Infection in Laying Hens

    PubMed Central

    Pande, Vivek V.; Devon, Rebecca L.; Sharma, Pardeep; McWhorter, Andrea R.; Chousalkar, Kapil K.

    2016-01-01

    Members of Salmonella enterica are frequently involved in egg and egg product related human food poisoning outbreaks worldwide. In Australia, Salmonella Typhimurium is frequently involved in egg and egg product related foodborne illness and Salmonella Mbandaka has also been found to be a contaminant of the layer farm environment. The ability possessed by Salmonella Enteritidis to colonize reproductive organs and contaminate developing eggs has been well-described. However, there are few studies investigating this ability for Salmonella Typhimurium. The hypothesis of this study was that the Salmonella Typhimurium can colonize the gut for a prolonged period of time and that horizontal infection through feces is the main route of egg contamination. At 14 weeks of age hens were orally infected with either S. Typhimurium PT 9 or S. Typhimurium PT 9 and Salmonella Mbandaka. Salmonella shedding in feces and eggs was monitored for 15 weeks post-infection. Egg shell surface and internal contents of eggs laid by infected hens were cultured independently for detection of Salmonella spp. The mean Salmonella load in feces ranged from 1.54 to 63.35 and 0.31 to 98.38 most probable number/g (MPN/g) in the S. Typhimurium and S. Typhimurium + S. Mbandaka group, respectively. No correlation was found between mean fecal Salmonella load and frequency of egg shell contamination. Egg shell contamination was higher in S. Typhimurium + S. Mbandaka infected group (7.2% S. Typhimurium, 14.1% S. Mbandaka) compared to birds infected with S. Typhimurium (5.66%) however, co-infection had no significant impact on egg contamination by S. Typhimurium. Throughout the study Salmonella was not recovered from internal contents of eggs laid by hens. Salmonella was isolated from different segments of oviduct of hens from both the groups, however pathology was not observed on microscopic examination. This study investigated Salmonella shedding for up to 15 weeks p.i which is a longer period of time

  10. Multiplex PCR for the concurrent detection and differentiation of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium

    PubMed Central

    Pui, Chai Fung; Wong, Woan Chwen; Chai, Lay Ching; Lee, Hai Yen; Noorlis, Ahmad; Zainazor, Tuan Chilek Tuan; Tang, John Yew Huat; Ghazali, Farinazleen Mohamad; Cheah, Yoke Kqueen; Nakaguchi, Yoshitsugu; Nishibuchi, Mitsuaki; Radu, Son

    2011-01-01

    Salmonellosis outbreaks involving typhoid fever and human gastroenteritis are important diseases in tropical countries where hygienic conditions are often not maintained. A rapid and sensitive method to detect Salmonella spp., Salmonella Typhi and Salmonella Typhimurium is needed to improve control and surveillance of typhoid fever and Salmonella gastroenteritis. Our objective was the concurrent detection and differentiation of these food-borne pathogens using a multiplex PCR. We therefore designed and optimized a multiplex PCR using three specific PCR primer pairs for the simultaneous detection of these pathogens. The concentration of each of the primer pairs, magnesium chloride concentration, and primer annealing temperature were optimized before verification of the specificity of the primer pairs. The target genes produced amplicons at 429 bp, 300 bp and 620 bp which were shown to be 100% specific to each target bacterium, Salmonella spp., Salmonella Typhi and Salmonella Typhimurium, respectively. PMID:22028607

  11. Mucosal Inflammatory Response to Salmonella typhimurium Infection

    PubMed Central

    Patel, Samir; McCormick, Beth A.

    2014-01-01

    The human intestinal epithelium consists of a single layer of epithelial cells that forms a barrier against food antigens and the resident microbiota within the lumen. This delicately balanced organ functions in a highly sophisticated manner to uphold the fidelity of the intestinal epithelium and to eliminate pathogenic microorganisms. On the luminal side, this barrier is fortified by a thick mucus layer, and on the serosal side exists the lamina propria containing a resident population of immune cells. Pathogens that are able to breach this barrier disrupt the healthy epithelial lining by interfering with the regulatory mechanisms that govern the normal balance of intestinal architecture and function. This disruption results in a coordinated innate immune response deployed to eliminate the intruder that includes the release of antimicrobial peptides, activation of pattern-recognition receptors, and recruitment of a variety of immune cells. In the case of Salmonella enterica serovar typhimurium (S. typhimurium) infection, induction of an inflammatory response has been linked to its virulence mechanism, the type III secretion system (T3SS). The T3SS secretes protein effectors that exploit the host’s cell biology to facilitate bacterial entry and intracellular survival, and to modulate the host immune response. As the role of the intestinal epithelium in initiating an immune response has been increasingly realized, this review will highlight recent research that details progress made in understanding mechanisms underlying the mucosal inflammatory response to Salmonella infection, and how such inflammatory responses impact pathogenic fitness of this organism. PMID:25071772

  12. IlvHI locus of Salmonella typhimurium.

    PubMed

    Squires, C H; De Felice, M; Lago, C T; Calvo, J M

    1983-06-01

    In Escherichia coli K-12, the ilvHI locus codes for one of two acetohydroxy acid synthase isoenzymes. A region of the Salmonella typhimurium genome adjacent to the leucine operon was cloned on plasmid pBR322, yielding plasmids pCV47 and pCV49 (a shortened version of pCV47). This region contains DNA homologous to the E. coli ilvHI locus, as judged by hybridization experiments. Plasmid pCV47 did not confer isoleucine-valine prototrophy upon either E. coli or S. typhimurium strains lacking acetohydroxy acid synthase activity, suggesting that S. typhimurium lacks a functional ilvHI locus. However, isoleucine-valine prototrophs were readily isolated from such strains after mutagenesis with nitrosoguanidine. In one case we found that the Ilv+ phenotype resulted from an alteration in bacterial DNA on the plasmid (new plasmid designated pCV50). Furthermore, a new acetohydroxy acid synthase activity was observed in Ilv+ revertants; this enzyme was similar to E. coli acetohydroxy acid synthase III in its lack of activity at low pH. This new activity was correlated with the appearance in minicells of a new polypeptide having an approximate molecular weight of 61,000. Strains carrying either pCV49 or pCV50 produced a substantial amount of ilvHI-specific mRNA. These results, together with results from other laboratories, suggest that S. typhimurium has functional ilvB and ilvG genes and a cryptic ilvHI locus. E. coli K-12, on the other hand, has functional ilvB and ilvHI genes and a cryptic ilvG locus. PMID:6189818

  13. Persistence of Salmonella typhimurium on Fabrics

    PubMed Central

    Wilkoff, Lee J.; Westbrook, Louise; Dixon, Glen J.

    1969-01-01

    The persistence of Salmonella typhimurium (V-31) on wool blanket, wool gabardine, cotton sheeting, cotton knit jersey, cotton terry cloth, and cotton wash-and-wear fabrics was studied. Three methods of exposure were employed to contaminate the fabrics: direct contact, aerosol, and a lyophilized mixture of bacteria and dust having a high content of textile fibers. After contamination, the fabrics were held in 35 or 78% relative humidity at 25 C. The persistence time of S. typhimurium on fabrics held in 35% relative humidity was substantially longer when the fabrics were contaminated by direct contact or by exposure to dust containing bacteria than when contaminated by exposure to aerosolized cultures. Viable bacterial populations persisted for 24 weeks at relatively high population densities on swatches of wool gabardine, cotton sheeting, cotton knit jersey, and cotton terry cloth exposed by direct contact and held in a humidity of 35%. In 78% humidity, bacterial populations persisted on the fabrics for relatively shorter periods of time regardless of the mode of contamination or fabric type. This organism retained its virulence for Swiss mice after being recovered from wool gabardine swatches held 8 weeks in humidities of 35 or 78% and from cotton terry cloth swatches held 6 weeks in the same humidities. Images PMID:4896883

  14. Genetic map of Salmonella typhimurium, edition VIII.

    PubMed Central

    Sanderson, K E; Hessel, A; Rudd, K E

    1995-01-01

    We present edition VIII of the genetic map of Salmonella typhimurium LT2. We list a total of 1,159 genes, 1,080 of which have been located on the circular chromosome and 29 of which are on pSLT, the 90-kb plasmid usually found in LT2 lines. The remaining 50 genes are not yet mapped. The coordinate system used in this edition is neither minutes of transfer time in conjugation crosses nor units representing "phage lengths" of DNA of the transducing phage P22, as used in earlier editions, but centisomes and kilobases based on physical analysis of the lengths of DNA segments between genes. Some of these lengths have been determined by digestion of DNA by rare-cutting endonucleases and separation of fragments by pulsed-field gel electrophoresis. Other lengths have been determined by analysis of DNA sequences in GenBank. We have constructed StySeq1, which incorporates all Salmonella DNA sequence data known to us. StySeq1 comprises over 548 kb of nonredundant chromosomal genomic sequences, representing 11.4% of the chromosome, which is estimated to be just over 4,800 kb in length. Most of these sequences were assigned locations on the chromosome, in some cases by analogy with mapped Escherichia coli sequences. PMID:7603411

  15. Salmonella typhimurium Invasion Induces Apoptosis in Infected Macrophages

    NASA Astrophysics Data System (ADS)

    Monack, Denise M.; Raupach, Barbel; Hromockyj, Alexander E.; Falkow, Stanley

    1996-09-01

    Invasive Salmonella typhimurium induces dramatic cytoskeletal changes on the membrane surface of mammalian epithelial cells and RAW264.7 macrophages as part of its entry mechanism. Noninvasive S. typhimurium strains are unable to induce this membrane ruffling. Invasive S. typhimurium strains invade RAW264.7 macrophages in 2 h with 7- to 10-fold higher levels than noninvasive strains. Invasive S. typhimurium and Salmonella typhi, independent of their ability to replicate intracellularly, are cytotoxic to RAW264.7 macrophages and, to a greater degree, to murine bone marrow-derived macrophages. Here, we show that the macrophage cytotoxicity mediated by invasive Salmonella is apoptosis, as shown by nuclear morphology, cytoplasmic vacuolization, and host cell DNA fragmentation. S. typhimurium that enter cells causing ruffles but are mutant for subsequent intracellular replication also initiate host cell apoptosis. Mutant S. typhimurium that are incapable of inducing host cell membrane ruffling fail to induce apoptosis. The activation state of the macrophage plays a significant role in the response of macrophages to Salmonella invasion, perhaps indicating that the signal or receptor for initiating programmed cell death is upregulated in activated macrophages. The ability of Salmonella to promote apoptosis may be important for the initiation of infection, bacterial survival, and escape of the host immune response.

  16. 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.

  17. 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

  18. 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. PMID:26846809

  19. Recognition of Salmonella Typhimurium by Immobilized Phage P22 Monolayers

    PubMed Central

    Handa, Hitesh; Gurczynski, Stephen; Jackson, Matthew P.; Auner, Gregory; Mao, Guangzhao

    2009-01-01

    Phages are promising alternatives to antibodies as the biorecognition element in a variety of biosensing applications. In this study, a monolayer of bacteriophage P22 whose tailspike proteins specifically recognize Salmonella serotypes was covalently bound to glass substrates through a bifunctional cross linker 3-aminopropyltrimethoxysilane. The specific binding of Salmonella typhimurium to the phage monolayer was studied by enzyme-linked immunosorbent assay and atomic force microscopy. Escherichia coli and a Gram-positive bacterium Listeria monocytogenes were also studied as control bacteria. The P22 particles show strong binding affinity to Salmonella typhimurium. In addition, the dried P22 monolayer maintained 50% binding capacity to Salmonella typhimurium after a one-week storage time. This is a promising method to prepare phage monolayer coatings on surface plasmon resonance and acoustic biosensor substrates in order to utilize the nascent phage display technology. PMID:19461940

  20. Suppressors of Recb Mutations in Salmonella Typhimurium

    PubMed Central

    Benson, N. R.; Roth, J.

    1994-01-01

    Using a screen that directly assesses transductional proficiency, we have isolated suppressors of recB mutations in Salmonella typhimurium. The alleles of sbcB reported here are phenotypically distinct from those isolated in Escherichia coli in that they restore recombination proficiency (Rec(+)), resistance to ultraviolet light (UV(R)), and mitomycin C resistance (MC(R)) in the absence of an accompanying sbcCD mutation. In addition the sbcB alleles reported here are co-dominant to sbcB(+). We have also isolated insertion and deletion mutants of the sbcB locus. These null mutations suppress only the UV(S) phenotype of recB mutants. We have also isolated sbcCD mutations, which map near proC. These sbcCD mutations increase the viability, recombination proficiency and MC(R) of both the transductional recombination suppressors (sbcB1 & sbcB6) and the sbcB null mutations. S. typhimurium recB sbcB1 sbcCD8 strains are 15-fold more recombination proficient than wild-type strains. The increase in transductants in these strains is accompanied by a loss of abortive transductants suggesting that these fragments are accessible to the mutant recombination apparatus. Using tandem duplications, we have constructed sbcB merodiploids and found that, in a recB mutant sbcCD(+) genetic background, the sbcB(+) allele is dominant to sbcB1 for transductional recombination but co-dominant for UV(R) and MC(R). However, in a recB sbcCD8 genetic background, the sbcB1 mutation is co-dominant to sbcB(+) for all phenotypes. Our results lead us to suggest that the SbcB and SbcCD proteins have roles in RecBCD-dependent recombination. PMID:8001778

  1. Hydrophobic peptide auxotrophy in Salmonella typhimurium.

    PubMed Central

    Brãnes, L V; Somers, J M; Kay, W W

    1981-01-01

    The growth of a pleiotropic membrane mutant of Salmonella typhimurium with modified lipopolysaccharide composition was found to be strictly dependent on the peptone component of complex media. Nutritional Shiftdown into minimal media allowed growth for three to four generations. Of 20 commercial peptones, only enzymatic digests supported growth to varying degrees. Neither trace cations, amino acids, vitamins, carbohydrates, lipids, glutathione, polyamines, carbodimides, nor synthetic peptides stimulated growth; however, cells still metabolized carbohydrates, and amino acid transport systems were shown to be functional. A tryptic digest of casein was fractionated into four electrophoretically different peptide fractions of 1,000 to 1,200 molecular weight which supported growth to varying degrees. The best of these was further fractionated to two highly hydrophopic peptides. N-terminal modifications eliminated biological activity. Fluorescein-conjugated goat antibody to rabbit immunoglobulin G was used as a probe to detect antipeptide antibody-peptide complexes on membrane preparations. Cells grown on peptone distributed the peptide into both inner and outer membranes. The peptide could be removed with chaotropic agents, and cells had to be pregrown in peptone-containing media to bind the hydrophobic peptide. The gene (hyp) responsible for peptide auxotrophy was mapped at 44 to 45 units by conjugation. Images PMID:7024254

  2. Comparison of the environmental survival characteristics of Salmonella Dublin and Salmonella Typhimurium.

    PubMed

    Kirchner, Miranda J; Liebana, Ernesto; McLaren, Ian; Clifton-Hadley, Felicity A; Wales, Andrew D; Davies, Robert H

    2012-10-12

    To examine possible correlations in bovine Salmonella isolates between environmental survival and serovar-associated epidemiological patterns, bovine field isolates of Salmonella serovars Typhimurium and Dublin (two each) were inoculated into bovine faeces slurry and tested monthly by culture for survival during a six-month period of storage at a variable ambient temperature in a disused animal transporter. Low moisture conditions, where the slurry was dried onto wooden dowels, increased detectable survival of a low-level inoculum by up to five months, compared with wet slurry. A more modest increase of survival time was seen with storage of wet slurry under refrigeration at 4°C. Under both dry and wet conditions, the concentration of culturable Salmonella Typhimurium declined at a slower rate than did that of Salmonella Dublin. Salmonella that was naturally contaminating bovine faeces from farms with Salmonella Typhimurium did not show superior survival times compared with Salmonella Typhimurium that had been artificially inoculated into samples. The differing survival characteristics of the two serovars that was observed in environmental faeces may complement their different modes of infection in cattle. Salmonella Dublin, being a bovine host-adapted strain that establishes chronic infection in some animals, may have less need to survive for a prolonged period outside of its host than does Salmonella Typhimurium. PMID:22565008

  3. A Protocol to Infect Caenorhabditis elegans with Salmonella typhimurium

    PubMed Central

    Zhang, Jiuli; Jia, Kailiang

    2014-01-01

    In the last decade, C. elegans has emerged as an invertebrate organism to study interactions between hosts and pathogens, including the host defense against gram-negative bacterium Salmonella typhimurium. Salmonella establishes persistent infection in the intestine of C. elegans and results in early death of infected animals. A number of immunity mechanisms have been identified in C. elegans to defend against Salmonella infections. Autophagy, an evolutionarily conserved lysosomal degradation pathway, has been shown to limit the Salmonella replication in C. elegans and in mammals. Here, a protocol is described to infect C. elegans with Salmonella typhimurium, in which the worms are exposed to Salmonella for a limited time, similar to Salmonella infection in humans. Salmonella infection significantly shortens the lifespan of C. elegans. Using the essential autophagy gene bec-1 as an example, we combined this infection method with C. elegans RNAi feeding approach and showed this protocol can be used to examine the function of C. elegans host genes in defense against Salmonella infection. Since C. elegans whole genome RNAi libraries are available, this protocol makes it possible to comprehensively screen for C. elegans genes that protect against Salmonella and other intestinal pathogens using genome-wide RNAi libraries. PMID:24998902

  4. Assessment of attenuated Salmonella vaccine strains in controlling experimental Salmonella Typhimurium infection in chickens

    PubMed Central

    Pei, Yanlong; Parreira, Valeria R.; Roland, Kenneth L.; Curtiss, Roy; Prescott, John F.

    2014-01-01

    Salmonella hold considerable promise as vaccine delivery vectors for heterologous antigens in chickens. Such vaccines have the potential additional benefit of also controlling Salmonella infection in immunized birds. As a way of selecting attenuated strains with optimal immunogenic potential as antigen delivery vectors, this study screened 20 novel Salmonella Typhimurium vaccine strains, differing in mutations associated with delayed antigen synthesis and delayed attenuation, for their efficacy in controlling colonization by virulent Salmonella Typhimurium, as well as for their persistence in the intestine and the spleen. Marked differences were observed between strains in these characteristics, which provide the basis for selection for further study as vaccine vectors. PMID:24396177

  5. Assessment of attenuated Salmonella vaccine strains in controlling experimental Salmonella Typhimurium infection in chickens.

    PubMed

    Pei, Yanlong; Parreira, Valeria R; Roland, Kenneth L; Curtiss, Roy; Prescott, John F

    2014-01-01

    Salmonella hold considerable promise as vaccine delivery vectors for heterologous antigens in chickens. Such vaccines have the potential additional benefit of also controlling Salmonella infection in immunized birds. As a way of selecting attenuated strains with optimal immunogenic potential as antigen delivery vectors, this study screened 20 novel Salmonella Typhimurium vaccine strains, differing in mutations associated with delayed antigen synthesis and delayed attenuation, for their efficacy in controlling colonization by virulent Salmonella Typhimurium, as well as for their persistence in the intestine and the spleen. Marked differences were observed between strains in these characteristics, which provide the basis for selection for further study as vaccine vectors. PMID:24396177

  6. [Chronic Salmonella typhimurium diarrhea in an immunocompetent patient].

    PubMed

    Mellado-Ferreiro, M; Jarne-Betrán, V; Arteaga-Mazuelas, M; Abínzano-Guillén, M L

    2016-01-01

    Chronic diarrhea caused by infection in immunocompetent patients is an infrequent condition in developed countries, although certain pathogens,generally parasites (Giardia lamblia, Isospora belli,Cryptosporidium, Cyclospora, Strongyloides, Ameba,Trichuris and Schistosoma) and some bacteria (Aeromonas,Plesiomonas, Campylobacter, Clostridium difficile, Salmonella or Mycobacterium tuberculosis)can cause persistent diarrhea.We present the case of a patient who showed Salmonella typhimurium in his stool culture and recovered following treatment with levofloxacin for 7 days. PMID:27125610

  7. Salmonella typhimurium epidural empyema in an HIV-infected patient

    PubMed Central

    Hachfi, Wissem; Bellazreg, Foued; Ladib, Mohamed; Kaabia, Naoufel; Khalifa, Mabrouk; Krifa, Hedi; Letaief, Amel

    2009-01-01

    Salmonella focal intracranial infections are reported rarely. They tend to occur in immunocompromised patients. We present here a case of Salmonella typhimurium epidural empyema, with osteomyelitis of the adjacent frontal bone, in a 37-year-old human immunodeficiency virus positive man who presented with a three-day history of headache, fever, and sweats. He was treated successfully with antibiotics and surgical drainage. PMID:24470883

  8. Internal Colonization of Salmonella enterica Serovar Typhimurium in Tomato Plants

    PubMed Central

    Gu, Ganyu; Hu, Jiahuai; Cevallos-Cevallos, Juan M.; Richardson, Susanna M.; Bartz, Jerry A.; van Bruggen, Ariena H. C.

    2011-01-01

    Several Salmonella enterica outbreaks have been traced back to contaminated tomatoes. In this study, the internalization of S. enterica Typhimurium via tomato leaves was investigated as affected by surfactants and bacterial rdar morphotype, which was reported to be important for the environmental persistence and attachment of Salmonella to plants. Surfactants, especially Silwet L-77, promoted ingress and survival of S. enterica Typhimurium in tomato leaves. In each of two experiments, 84 tomato plants were inoculated two to four times before fruiting with GFP-labeled S. enterica Typhimurium strain MAE110 (with rdar morphotype) or MAE119 (without rdar). For each inoculation, single leaflets were dipped in 109 CFU/ml Salmonella suspension with Silwet L-77. Inoculated and adjacent leaflets were tested for Salmonella survival for 3 weeks after each inoculation. The surface and pulp of ripe fruits produced on these plants were also examined for Salmonella. Populations of both Salmonella strains in inoculated leaflets decreased during 2 weeks after inoculation but remained unchanged (at about 104 CFU/g) in week 3. Populations of MAE110 were significantly higher (P<0.05) than those of MAE119 from day 3 after inoculation. In the first year, nine fruits collected from one of the 42 MAE119 inoculated plants were positive for S. enterica Typhimurium. In the second year, Salmonella was detected in adjacent non-inoculated leaves of eight tomato plants (five inoculated with strain MAE110). The pulp of 12 fruits from two plants inoculated with MAE110 was Salmonella positive (about 106 CFU/g). Internalization was confirmed by fluorescence and confocal laser microscopy. For the first time, convincing evidence is presented that S. enterica can move inside tomato plants grown in natural field soil and colonize fruits at high levels without inducing any symptoms, except for a slight reduction in plant growth. PMID:22096553

  9. 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. PMID:23827803

  10. Poor biofilm-forming ability and long-term survival of invasive Salmonella Typhimurium ST313.

    PubMed

    Ramachandran, Girish; Aheto, Komi; Shirtliff, Mark E; Tennant, Sharon M

    2016-07-01

    Salmonella enterica serovar Typhimurium, an enteric pathogen that causes a self-limiting gastroenteritis, forms biofilms on different surfaces. In sub-Saharan Africa, Salmonella Typhimurium of a novel sequence type (ST) 313 was identified and produces septicemia in the absence of gastroenteritis. No animal reservoir has been identified, and it is hypothesized that transmission occurs via human to human. In this study, we show that invasive Salmonella Typhimurium ST313 strains from Mali are poor biofilm producers compared to Salmonella Typhimurium ST19 strains, which are found worldwide and are known to be associated with gastroenteritis. We evaluated biofilms using crystal violet staining, examination of the red, dry and rough morphotype, pellicle formation and a continuous flow system. One month-old Salmonella Typhimurium ST19 colonies survived in the absence of exogenous nutrients and were highly resistant to sodium hypochlorite treatment compared to Salmonella Typhimurium ST313. This study for the first time demonstrates the comparative biofilm-forming ability and long-term survival of clinical Salmonella Typhimurium ST19 and ST313 isolates. Salmonella Typhimurium ST19 strains are strong biofilm producers and can survive desiccation compared to Salmonella Typhimurium ST313 that form weak biofilms and survive poorly following desiccation. Our data suggest that like Salmonella Typhi, Salmonella Typhimurium ST313 lack mechanisms that allow it to persist in the environment. PMID:27222487

  11. 40 CFR 79.68 - Salmonella typhimurium reverse mutation assay.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... recommendations as specified under 40 CFR 79.60, the following specific information shall be reported: (i... consulted. (1) 40 CFR 798.5265, The Salmonella typhimurium reverse mutation asay. (2) Ames, B.N., McCann, J..., passed through a sorbent resin to trap semi-volatile gases. Bacteria are separately exposed to...

  12. 40 CFR 79.68 - Salmonella typhimurium reverse mutation assay.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... recommendations as specified under 40 CFR 79.60, the following specific information shall be reported: (i... consulted. (1) 40 CFR 798.5265, The Salmonella typhimurium reverse mutation asay. (2) Ames, B.N., McCann, J... mononucleotide, exogenous glucose 6-phosphate dehydrogenase, NADH and excess of glucose-6-phosphate. (5)...

  13. 40 CFR 79.68 - Salmonella typhimurium reverse mutation assay.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... established in the laboratory by historical control values. (iii) Bacterial growth. Fresh cultures of bacteria... recommendations as specified under 40 CFR 79.60, the following specific information shall be reported: (i... consulted. (1) 40 CFR 798.5265, The Salmonella typhimurium reverse mutation asay. (2) Ames, B.N., McCann,...

  14. 40 CFR 79.68 - Salmonella typhimurium reverse mutation assay.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... established in the laboratory by historical control values. (iii) Bacterial growth. Fresh cultures of bacteria... recommendations as specified under 40 CFR 79.60, the following specific information shall be reported: (i... consulted. (1) 40 CFR 798.5265, The Salmonella typhimurium reverse mutation asay. (2) Ames, B.N., McCann,...

  15. Recognition of Salmonella typhimurium by immobilized phage P22 monolayers

    NASA Astrophysics Data System (ADS)

    Handa, Hitesh; Gurczynski, Stephen; Jackson, Matthew P.; Auner, Gregory; Walker, Jeremy; Mao, Guangzhao

    2008-04-01

    Phages are promising alternatives to antibodies as the biorecognition element in a variety of biosensing applications. In this study, a monolayer of bacteriophage P22 whose tailspike proteins specifically recognize Salmonella serotypes was covalently bound to glass substrates through a bifunctional cross linker 3-aminopropyltrimethoxysilane. The specific binding of Salmonella typhimurium to the phage monolayer was studied by enzyme-linked immunosorbent assay and atomic force microscopy. Escherichia coli and a Gram-positive bacterium Listeria monocytogenes were also studied as control bacteria. The P22 particles show strong binding affinity to S. typhimurium. In addition, the dried P22 monolayer maintained 50% binding capacity to S. typhimurium after a one-week storage time. This is a promising method to prepare phage monolayer coatings on surface plasmon resonance and acoustic biosensor substrates in order to utilize the nascent phage display technology.

  16. ISOLATIONS OF SALMONELLA ENTERITIDIS AND SALMONELLA TYPHIMURIUM FROM MICE IN POULTRY FLOCKS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    House mice (Mus musculus), laying hens and the environments of thirty-nine poultry flocks in Pennsylvania, USA were cultured for Salmonella enteritidis and Salmonella typhimurium. Mice spleen and intestinal samples were each cultured, individually, with S. enteritidis isolated from fifteen and thi...

  17. Targeting Tumors with Salmonella Typhimurium - Potential for Therapy

    PubMed Central

    Wall, Daniel M.; Srikanth, C.V.; McCormick, Beth A.

    2010-01-01

    When one considers the organism Salmonella enterica serotype Typhimurium (S. Typhimurium), one usually thinks of the Gram-negative enteric pathogen that causes the severe food borne illness, gastroentertitis. In this context, the idea of Salmonella being exploited as a cancer therapeutic seems pretty remote. However, there has been an escalating interest in the development of tumor-therapeutic bacteria for use in the treatment of a variety of cancers. This strategy takes advantage of the remarkable ability of certain bacteria to preferentially replicate and accumulate within tumors. In the case of S. Typhimurium, this organism infects and selectively grows within implanted tumors, achieving tumor/normal tissue ratios of approximately 1,000:1. Salmonella also has some attractive properties well suited for the design of a chemotherapeutic agent. In particular, this pathogen can easily be manipulated to carry foreign genes, and since this species is a facultative anaerobe, it is able to survival in both oxygenated and hypoxic conditions, implying this organism could colonize both small metastatic lesions as well as larger tumors. These observations are the impetus to a burgeoning field focused on the development of Salmonella as a clinically useful anti-cancer agent. We will discuss three cutting edge technologies employing Salmonella to target tumors. PMID:21321381

  18. Salmonella typhimurium resistant to silver nitrate, chloramphenicol, and ampicillin.

    PubMed

    McHugh, G L; Moellering, R C; Hopkins, C C; Swartz, M N

    1975-02-01

    A strain of Salmonella typhimurium appeared sequentially in three patients in a burn unit, and epidemiological study suggested the occurrence of person-to-person spread. This organism was responsible for both colonisation and invasive infection in these patients whose burn surfaces were receiving topical treatment with 0.5% silver nitrate (AgNO3) solution. The antibiotic and metal ionsusceptibility pattern of this strain of S. typhimurium was unique and disturbing: resistant to silver nitrate, mercuric chloride, ampicillin, chloramphenicol, tetracycline, streptomycin, and sulphonamides. This pattern of multiple resistances could be transferred by invitro mating experiments to sensitive recipient strains of Escherichia coli and S. typhimurium. Further transfer of these resistances could be consumated between different strains of E. coli. A survey of other salmonella strains isolated from patients in this hospital without thermal burns did not reveal this pattern of resistance. Also, strains of S. typhimurium, isolated elsewhere and showing simultaneous resistance to both ampicillin and chloramphenicol, were not resistant to AgNO3 in vitro. The very real danger of this strain of S. typhimurium in burn units stems from its resistance to the two most effective antibiotics (ampicillin and chloramphenicol) available for systemic therapy; and this threat may be compounded through the selection effected by the widespread topical use of AgNO3 solutions and sulphonamide preparations on burned surfaces. PMID:46385

  19. Protection Against Salmonella Typhimurium, Salmonella Gallinarum, and Salmonella Enteritidis Infection in Layer Chickens Conferred by a Live Attenuated Salmonella Typhimurium Strain

    PubMed Central

    2015-01-01

    In the present study, we investigated the protection conferred by a live attenuated Salmonella enterica serovar Typhimurium (ST) strain against Salmonella Typhimurium, Salmonella Gallinarum (SG), and Salmonella Enteritidis (SE) infection in layer chickens. Birds were orally primed with the attenuated ST strain at 7 days of age and then boosted at 4 weeks post prime immunization (PPI). Sequential monitoring of plasma IgG and mucosal secretory IgA (sIgA) levels revealed that inoculation with ST induced a significant antibody response to antigens against ST, SE, and SG. Moreover, significant lymphoproliferative responses to the 3 Salmonella serovars were observed in the immunized group. We also investigated protection against virulent ST, SE, and SG strain challenge. Upon virulent SG challenge, the immunized group showed significantly reduced mortality compared to the non-immunized group. The reduced persistence of the virulent ST and SE challenge strains in the liver, spleen, and cecal tissues of the immunized group suggests that immunization with the attenuated ST strain may not only protect against ST infection but can also confer cross protection against SE and SG infection. PMID:25713506

  20. Protein Acetylation Is Involved in Salmonella enterica Serovar Typhimurium Virulence.

    PubMed

    Sang, Yu; Ren, Jie; Ni, Jinjing; Tao, Jing; Lu, Jie; Yao, Yu-Feng

    2016-06-01

    Salmonella causes a range of diseases in different hosts, including enterocolitis and systemic infection. Lysine acetylation regulates many eukaryotic cellular processes, but its function in bacteria is largely unexplored. The acetyltransferase Pat and NAD(+)-dependent deacetylase CobB are involved in the reversible protein acetylation in Salmonella Typhimurium. Here, we used cell and animal models to evaluate the virulence of pat and cobB deletion mutants in S. Typhimurium and found that pat is critical for bacterial intestinal colonization and systemic infection. Next, to understand the underlying mechanism, genome-wide transcriptome was analyzed. RNA sequencing data showed that the expression of Salmonella pathogenicity island 1 (SPI-1) is partially dependent on pat In addition, we found that HilD, a key transcriptional regulator of SPI-1, is a substrate of Pat. The acetylation of HilD by Pat maintained HilD stability and was essential for the transcriptional activation of HilA. Taken together, these results suggest that a protein acetylation system regulates SPI-1 expression by controlling HilD in a posttranslational manner to mediate S. Typhimurium virulence. PMID:26810370

  1. Intestinal Cytokine Responses to Salmonella enterica Serovar Typhimurium Infection in Young Chicks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar typhimurium is one of the most frequently isolated strains in human salmonellosis worldwide, and is commonly found in broilers. Successful prevention and control of Salmonella colonization in poultry require better understanding of intestinal mucosal immune response to ...

  2. Salmonella Typhimurium exploits inflammation to its own advantage in piglets

    PubMed Central

    Chirullo, Barbara; Pesciaroli, Michele; Drumo, Rosanna; Ruggeri, Jessica; Razzuoli, Elisabetta; Pistoia, Claudia; Petrucci, Paola; Martinelli, Nicola; Cucco, Lucilla; Moscati, Livia; Amadori, Massimo; Magistrali, Chiara F.; Alborali, Giovanni L.; Pasquali, Paolo

    2015-01-01

    Salmonella Typhimurium (S. Typhimurium) is responsible for foodborne zoonotic infections that, in humans, induce self-limiting gastroenteritis. The aim of this study was to evaluate whether the wild-type strain S. Typhimurium (STM14028) is able to exploit inflammation fostering an active infection. Due to the similarity between human and porcine diseases induced by S. Typhimurium, we used piglets as a model for salmonellosis and gastrointestinal research. This study showed that STM14028 is able to efficiently colonize in vitro porcine mono-macrophages and intestinal columnar epithelial (IPEC-J2) cells, and that the colonization significantly increases with LPS pre-treatment. This increase was then reversed by inhibiting the LPS stimulation through LPS antagonist, confirming an active role of LPS stimulation in STM14028-intracellular colonization. Moreover, LPS in vivo treatment increased cytokines blood level and body temperature at 4 h post infection, which is consistent with an acute inflammatory stimulus, capable to influence the colonization of STM14028 in different organs and tissues. The present study proves for the first time that in acute enteric salmonellosis, S. Typhimurium exploits inflammation for its benefit in piglets. PMID:26441914

  3. Serological response of swine to an attenuated Salmonella enterica serovar Typhimurium strain that reduces gastrointestinal colonization, fecal shedding and disease due to virulent Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swine are often asymptomatic carriers of Salmonella spp. Interventions are needed to limit Salmonella colonization of swine to enhance food safety. An attenuated Salmonella enterica serovar Typhimurium mutant strain (BBS 202) was tested in swine to determine whether vaccination could provide protect...

  4. Phagocytic and chemiluminescent responses of mouse peritoneal macrophages to living and killed Salmonella typhimurium and other bacteria.

    PubMed Central

    Tomita, T; Blumenstock, E; Kanegasaki, S

    1981-01-01

    In the presence of luminol, resident as well as thioglycolate-induced and immunized macrophages emitted chemiluminescence more efficiently when the cells were exposed to living Salmonella typhimurium than when they were exposed to the same bacterium killed by ultraviolet light or heat. This phenomenon was observed whether or not the bacterium was opsonized. The different response to living and killed bacteria was also found with Escherichia coli, Pseudomonas aeruginosa, Proteus morganii, and Enterobacter aerogenes, but not with Shigella sonnei, Klebsiella pneumoniae, and Propionibacterium acnes. The results suggest that macrophages respond better to living, motile bacteria than to nonmotile or killed bacteria. The experimental results obtained with motility mutants of S. typhimurium, E. coli, and P. aeruginosa confirm that macrophages exposed to the motile bacteria emit chemiluminescence more efficiently and ingest the motile bacteria at a much faster rate than the nonmotile bacteria. Images PMID:6788707

  5. Immune reaction and survivability of salmonella typhimurium and salmonella infantis after infection of primary avian macrophages.

    PubMed

    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

  6. 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

  7. Persistence of salmonella typhimurium in nopal cladodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fresh produce associated outbreaks have increased in the last few years. E.coli O157:H7 and Salmonella have been causative agents of infection in these outbreaks. Fresh produce is consumed raw, and in the absence of terminal kill treatment, it is imperative to understand sources of contamination o...

  8. Persistence of salmonella Typhimurium in Nopal

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Having documented information available on the capability of Salmonella to remain in the cladode tissue it is important to understand the role of nopal on the lifecycle of enteropathogenic bacteria in humans, as well as for management and control programs of theses pathogens in plants. Because of th...

  9. The engineered Salmonella typhimurium inhibits tumorigenesis in advanced glioma

    PubMed Central

    Chen, Jian-qiang; Zhan, Yue-fu; Wang, Wei; Jiang, Sheng-nan; Li, Xiang-ying

    2015-01-01

    Objective To explore the antitumor role of the attenuated Salmonella typhimurium ΔppGpp with inducible cytolysin A (ClyA) in advanced stage of glioma. Materials and methods The C6 rat glioma cells were orthotopically implanted by surgery into the caudate nucleus of rat brains. The rats were then randomly divided into the treatment group (SL + ClyA) (n=12), negative control group (SL) (n=12), and control group (phosphate-buffered saline [PBS]) (n=12). In the treatment group, the attenuated S. typhimurium were transformed with the plasmid-encoded antitumor gene ClyA. The expression of ClyA was controlled by the TetR-regulated promoter in response to extracellular doxycycline. The plasmid also contained an imaging gene lux to allow illumination of the tumor infected by the bacteria. The rat glioma C6 cells were implanted into the caudate nucleus of all rats. The engineered S. typhimurium and respective controls were injected intravenously into the rats 21 days after initial tumor implantation. The pathological analysis of the glioma tumor was performed at 21 days and 28 days (7 days after doxycycline treatment) postimplantation. All rats underwent MRI (magnetic resonance imaging) and bioluminescence study at 21 days and 28 days postimplantation to detect tumor volume. The differences between the three groups in tumor volume and survival time were analyzed. Results Advanced stage glioma was detected at 21 days postimplantation. Bioluminescence showed that the engineered S. typhimurium accumulated in glioma tumors and disappeared in the normal reticuloendothelial tissues 3 days after intravenous injection. MRI showed that the tumor volume in the S. typhimurium with ClyA group were significantly reduced compared to the bacteria alone and no bacteria groups 7 days post-doxycycline treatment (P<0.05), while the necrotic tumor volume in the S. typhimurium with ClyA group and S. typhimurium alone group increased significantly compared to the control group (P<0.01). In

  10. Influence of hard water ions on the growth rate of Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of magnesium and calcium ions in process water on the growth of Salmonella typhimurium was evaluated to address the concerns for food quality and safety. Salmonella typhimurium was exposed to media containing 500 ppm and 1000 ppm of magnesium and calcium ions for 45 minutes followed by...

  11. Photonic plasmid stability of transformed Salmonella typhimurium: A comparison of three unique plasmids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acquiring a highly stable photonic plasmid in transformed Salmonella typhimurium for use in biophotonic studies of bacterial tracking in vivo is critical to experimental paradigm development. The objective of this study was to determine stability of transformed Salmonella typhimurium (S. typh-lux) u...

  12. Photonic Plasmid Stability of Transformed Salmonella Typhimurium: A Comparison of Three Unique Plasmids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Acquiring a highly stable photonic plasmid in transformed Salmonella Typhimurium for use in biophotonic studies of bacterial tracking in vivo is critical to experimental paradigm development. The objective of this study was to determine stability of transformed Salmonella Typhimurium (S....

  13. Using a surface plasmon resonance biosensor for rapid detection of salmonella typhimurium in chicken carcass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chicken is one of the most popular meat products in the world. Salmonella Typhimurium is a common foodborne pathogens associated with the processing of poultry. An optical Surface Plasmon Resonance (SPR) biosensor was sensitive to the presence of Salmonella Typhimurium in chicken carcass. The Spr...

  14. Detection of Salmonella typhimurium using polyclonal antibody immobilized magnetostrictive biosensors

    NASA Astrophysics Data System (ADS)

    Guntupalli, R.; Hu, Jing; Lakshmanan, Ramji S.; Wan, Jiehui; Huang, Shichu; Yang, Hong; Barbaree, James M.; Huang, T. S.; Chin, Bryan A.

    2006-05-01

    Novel mass-sensitive, magnetostrictive sensors have a characteristic resonant frequency that can be determined by monitoring the magnetic flux emitted by the sensor in response to an applied, time varying, magnetic field. This magnetostrictive platform has a unique advantage over conventional sensor platforms in that measurement is wireless or remote. These biosensors can thus be used in-situ for detecting pathogens and biological threat agents. In this work, we have used a magnetostrictive platform immobilized with a polyclonal antibody (the bio-molecular recognition element) to form a biosensor for the detection of Salmonella typhimurium. Upon exposure to solutions containing Salmonella typhimurium bacteria, the bacteria were bound to the sensor and the additional mass of the bound bacteria caused a shift in the sensor's resonant frequency. Responses of the sensors to different concentrations of S. typhimurium were recorded and the results correlated with those obtained from scanning electron microscopy (SEM) images of samples. Good agreement between the measured number of bound bacterial cells (attached mass) and frequency shifts were obtained. The longevity and specificity of the selected polyclonal antibody were also investigated and are reported.

  15. Occurrence of the toxin dehydroabietic acid in Salmonella typhimurium.

    PubMed

    Beier, R C; Oyofo, B A; Spates, G E

    2000-03-01

    Many strains of Salmonella typhimurium studied in our lab demonstrated marked differences in the pathogenicity for guinea pig, chicken and Hela cells. As a result, a pathogenic strain of S. typhimurium, strain 9SR2, was evaluated for lipophilic components that may be associated with virulence using gas chromatography/mass spectrometry. The hydroxylated fatty acids 2-hydroxytetradecanoic acid (2-OH-14:0) and 3-hydroxytetradecanoic acid (3-OH-14:0) often present in lipid A, a potent endotoxin, were observed as their methyl esters. The cyclic fatty acids methylene-hexadecanoic acid (C17delta) and methyleneoctadecanoic acid (C19delta) also were detected. The nephrotoxic and neurotoxic diterpenoid resin acid, dehydroabietic acid, was observed for the first time from S. typhimurium in both the total lipid and diglyceride fractions and determined as its methyl ester at m/z 314.2246. Due to its previously established toxicity, dehydroabietic acid may be a factor associated with virulence of S. typhimurium. PMID:10669023

  16. Sequence, regulation, and functions of fis in Salmonella typhimurium.

    PubMed Central

    Osuna, R; Lienau, D; Hughes, K T; Johnson, R C

    1995-01-01

    The fis operon from Salmonella typhimurium has been cloned and sequenced, and the properties of Fis-deficient and Fis-constitutive strains were examined. The overall fis operon organization in S. typhimurium is the same as that in Escherichia coli, with the deduced Fis amino acid sequences being identical between both species. While the open reading frames upstream of fis have diverged slightly, the promoter regions between the two species are also identical between -49 and +94. Fis protein and mRNA levels fluctuated dramatically during the course of growth in batch cultures, peaking at approximately 40,000 dimers per cell in early exponential phase, and were undetectable after growth in stationary phase. fis autoregulation was less effective in S. typhimurium than that in E. coli, which can be correlated with the absence or reduced affinity of several Fis-binding sites in the S. typhimurium fis promoter region. Phenotypes of fis mutants include loss of Hin-mediated DNA inversion, cell filamentation, reduced growth rates in rich medium, and increased lag times when the mutants are subcultured after prolonged growth in stationary phase. On the other hand, cells constitutively expressing Fis exhibited normal logarithmic growth but showed a sharp reduction in survival during stationary phase. During the course of these studies, the sigma 28-dependent promoter within the hin-invertible segment that is responsible for fljB (H2) flagellin synthesis was precisely located. PMID:7536730

  17. Clonal groups of Salmonella typhimurium in New York State.

    PubMed Central

    McDonough, P L; Timoney, J F; Jacobson, R H; Khakhria, R

    1989-01-01

    The epidemiology of 278 strains of Salmonella typhimurium isolated from 1973 to 1981 from animals in New York State was studied by using four "fingerprinting" techniques, bacteriophage type (B.R. Callow, J. Hyg. 57:346-359, 1959), biotype (J. P. Duguid, E. S. Anderson, G. A. Alfredsson, R. Barker, and D. C. Old, J. Med. Microbiol. 8:149-166, 1975), plasmid profile, and antibiogram. Phage type with biotype was the most useful marker for distinguishing clonal groups of S. typhimurium. Four clones of S. typhimurium predominated, i.e., phage type/biotypes U275/26, 49/26, 10/3, and 2/3. U275/26 and 49/26 were commonly found until 1976, but clones 10/3 and 2/3 were predominant after 1976. Comparison of results with data from Canada suggested a dissemination of strains of S. typhimurium between Canada and New York. Cattle were a common source of phage type 49, as has been observed in other countries. PMID:2656740

  18. Dispersal of Salmonella Typhimurium by rain splash onto tomato plants.

    PubMed

    Cevallos-Cevallos, Juan M; Danyluk, Michelle D; Gu, Ganyu; Vallad, Gary E; van Bruggen, Ariena H C

    2012-03-01

    Outbreaks of Salmonella enterica have increasingly been associated with tomatoes and traced back to production areas, but the spread of Salmonella from a point source onto plants has not been described. Splash dispersal by rain could be one means of dissemination. Green fluorescent protein-labeled, kanamycin-resistant Salmonella enterica sv. Typhimurium dispensed on the surface of plastic mulch, organic mulch, or soil at 10⁸ CFU/cm² was used as the point source in the center of a rain simulator. Tomato plants in soil with and without plastic or organic mulch were placed around the point source, and rain intensities of 60 and 110 mm/h were applied for 5, 10, 20, and 30 min. Dispersal of Salmonella followed a negative exponential model with a half distance of 3 cm at 110 mm/h. Dispersed Salmonella survived for 3 days on tomato leaflets, with a total decline of 5 log and an initial decimal reduction time of 10 h. Recovery of dispersed Salmonella from plants at the maximum observed distance ranged from 3 CFU/g of leaflet after a rain episode of 110 mm/h for 10 min on soil to 117 CFU/g of leaflet on plastic mulch. Dispersal of Salmonella on plants with and without mulch was significantly enhanced by increasing rain duration from 0 to 10 min, but dispersal was reduced when rainfall duration increased from 10 to 30 min. Salmonella may be dispersed by rain to contaminate tomato plants in the field, especially during rain events of 10 min and when plastic mulch is used. PMID:22410220

  19. Clustered Intracellular Salmonella enterica Serovar Typhimurium Blocks Host Cell Cytokinesis

    PubMed Central

    Durkin, Charlotte H.; Helaine, Sophie; Boucrot, Emmanuel

    2016-01-01

    Several bacterial pathogens and viruses interfere with the cell cycle of their host cells to enhance virulence. This is especially apparent in bacteria that colonize the gut epithelium, where inhibition of the cell cycle of infected cells enhances the intestinal colonization. We found that intracellular Salmonella enterica serovar Typhimurium induced the binucleation of a large proportion of epithelial cells by 14 h postinvasion and that the effect was dependent on an intact Salmonella pathogenicity island 2 (SPI-2) type 3 secretion system. The SPI-2 effectors SseF and SseG were required to induce binucleation. SseF and SseG are known to maintain microcolonies of Salmonella-containing vacuoles close to the microtubule organizing center of infected epithelial cells. During host cell division, these clustered microcolonies prevented the correct localization of members of the chromosomal passenger complex and mitotic kinesin-like protein 1 and consequently prevented cytokinesis. Tetraploidy, arising from a cytokinesis defect, is known to have a deleterious effect on subsequent cell divisions, resulting in either chromosomal instabilities or cell cycle arrest. In infected mice, proliferation of small intestinal epithelial cells was compromised in an SseF/SseG-dependent manner, suggesting that cytokinesis failure caused by S. Typhimurium delays epithelial cell turnover in the intestine. PMID:27185791

  20. Identification and sequence analysis of lpfABCDE, a putative fimbrial operon of Salmonella typhimurium.

    PubMed Central

    Bäumler, A J; Heffron, F

    1995-01-01

    A chromosomal region present in Salmonella typhimurium but absent from related species was identified by hybridization. A DNA probe originating from 78 min on the S. typhimurium chromosome hybridized with DNA from Salmonella enteritidis, Salmonella heidelberg, and Salmonella dublin but not with DNA from Salmonella typhi, Salmonella arizonae, Escherichia coli, and Shigella serotypes. Cloning and sequence analysis revealed that the corresponding region of the S. typhimurium chromosome encodes a fimbrial operon. Long fimbriae inserted at the poles of the bacterium were observed by electron microscopy when this fimbrial operon was introduced into a nonpiliated E. coli strain. The genes encoding these fimbriae were therefore termed lpfABCDE, for long polar fimbriae. Genetically, the lpf operon was found to be most closely related to the fim operon of S. typhimurium, both in gene order and in conservation of the deduced amino acid sequences. PMID:7721701

  1. Genetic organization of the Salmonella typhimurium ilv gene cluster.

    PubMed

    Blazey, D L; Burns, R O

    1979-01-01

    A number of Salmonella typhimurium ilv::Tn10 insertion strains were used to analyze the Salmonella ilv gene cluster. Tn10 generated ilv deletion mutants were employed in mapping experiments to conclusively define the gene order as ilvG-E-D-A-C. Examination of ilv enzyme levels confirms that the direction of transcription of ilvGEDA is from ilvG to ilvA. The major control locus, designated ilvO, is located before ilvG forming an ilvOGEDA transcriptional unit that is multivalently repressed by isoleucine, valine and leucine. Two internal promoters, one before ilvE and anonother before ilvD, are identified and are shown to provide repressed levels of the ilvE, D and A gene products. Possible regulation of transcription from these promoters in response to isoleucine limitation is discussed in terms of attenuation. PMID:395408

  2. Global Genomic Epidemiology of Salmonella enterica Serovar Typhimurium DT104

    DOE PAGESBeta

    Leekitcharoenphon, Pimlapas; Hendriksen, Rene S.; Le Hello, Simon; Weill, François-Xavier; Baggesen, Dorte Lau; Jun, Se-Ran; Ussery, David W.; Lund, Ole; Crook, Derrick W.; Wilson, Daniel J.; et al

    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

  3. 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

  4. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 r...

  5. Salmonella typhimurium mutants that downregulate phagocyte nitric oxide production.

    PubMed

    Eriksson, S; Björkman, J; Borg, S; Syk, A; Pettersson, S; Andersson, D I; Rhen, M

    2000-06-01

    To examine the potential and strategies of the facultative intracellular pathogen Salmonella typhimurium to increase its fitness in host cells, we applied a selection that enriches for mutants with increased bacterial growth yields in murine J774-A.1 macrophage-like cells. The selection, which was based on intracellular growth competition, rapidly yielded isolates that out-competed the wild-type strain during intracellular growth. J774-A.1 cells responded to challenge with S. typhimurium by mounting an inducible nitric oxide synthase (iNOS) mRNA and protein expression and a concomitant nitric oxide (NO) production. Inhibition of NO production with the use of the competitive inhibitor N-monomethyl-L-arginine (NMMA) resulted in a 20-fold increase in bacterial growth yield, suggesting that the NO response prevented bacterial intracellular growth. In accordance with this observation, five out of the nine growth advantage mutants isolated inhibited production of NO from J774-A.1 cells, despite an induction of iNOS mRNA and iNOS protein. Accompanying bacterial phenotypes included alterations in lipopolysaccharide structure and in the profiles of proteins secreted by invasion-competent bacteria. The results indicate that S. typhimurium has the ability to mutate in several different ways to increase its host fitness and that inhibition of iNOS activity may be a major adaptation. PMID:11207580

  6. Emerging antibiotic resistance in Salmonella typhimurium in Norway.

    PubMed

    Leegaard, T M; Caugnat, D A; Frøholm, L O; Høiby, E A; Lassen, J

    2000-12-01

    The antimicrobial resistance of 809 Salmonella Typhimurium isolates collected from humans in Norway between 1975 and 1998 was studied. The material was subdivided into domestic and foreign isolates according to whether the patient had recently travelled abroad or not. In imported isolates the largest increase in resistance was in 1996 when 35% of the isolates were multi-resistant. The first multi-resistant isolate acquired in Norway appeared in 1994, but already in 1998 23% of the isolates domestically acquired were multi-resistant, and a majority were S. Typhimurium DT104. We found no ciprofloxacin resistance in domestically acquired isolates. Amplified fragment length polymorphism analysis was performed on selected multi-resistant isolates. The method discriminated well between different multi-resistant isolates, but not between DT104 isolates. Resistant and multi-resistant S. Typhimurium were until 1998 essentially recovered from patients who had travelled abroad, but multi-resistant isolates, mainly DT104, are now also being transmitted within the country. PMID:11218197

  7. Mutation Leading to Increased Sensitivity to Chromium in Salmonella typhimurium

    PubMed Central

    Corwin, L. M.; Fanning, G. R.; Feldman, F.; Margolin, P.

    1966-01-01

    Corwin, L. M. (Walter Reed Army Institute of Research, Washington, D.C.), G. R. Fanning, F. Feldman, and P. Margolin. Mutation leading to increased sensitivity to chromium in Salmonella typhimurium. J. Bacteriol. 91:1509–1515. 1966.—Certain deletion mutants including the tryptophan operon in Salmonella typhimurium are unable to utilize several sugars as carbon sources in solid media, although they are able to grow in liquid media with these sugars. The addition of citrate or washing the agar with ethylenediaminetetraacetic acid permits growth on solid media. Analysis of the agar revealed that Fe3+ and Cr3+ were present at concentrations of 22 and 75 μm, respectively. The addition of Fe3+ to liquid media in 0.5 mm concentrations did not inhibit the wild type or the mutants. A similar concentration of Cr3+ did not inhibit the wild type, but concentrations as low as 0.01 to 0.05 mm inhibited the deletion mutants. Other metals were inhibitory at various concentrations, but none showed any significant differential effects on the mutants and the wild type. The increased sensitivity of the mutants to chromium may be due either to an increased permeability to Cr3+, resulting in higher effective intracellular concentrations and inhibition of one or more metabolic functions, or to a binding of Cr3+ to an altered cell wall, resulting in decreased permeability of required substrates. PMID:4956341

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. Resistant mechanism study of benzalkonium chloride selected Salmonella Typhimurium mutants.

    PubMed

    Guo, Wei; Cui, Shenghui; Xu, Xiao; Wang, Haoyan

    2014-02-01

    Benzalkonium chloride is one of the invaluable biocides that is extensively used in healthcare settings as well as in the food processing industry. After exposing wild-type Salmonella Typhimurium 14028s or its AcrAB inactivation mutant to gradually increasing levels of benzalkonium chloride, resistance mutants S-41, S-150, S-AB-23, S-AB-38, and S-AB-73 were selected and these mutants also showed a 2-64-fold stable minimum inhibitory concentration (MIC) increase to chloramphenicol, ciprofloxacin, nalidixic acid, and tetracycline. In S-41 and S-150, the expression of acrB was increased 2.7- and 7.6-fold, and ΔtolC or ΔacrAB mutants of S-41 and S-150 showed the same MICs to all tested antimicrobials as the equivalent Salmonella Typhimurium 14028s mutants. However, in S-AB-23, S-AB-38, and S-AB-73, the expression of acrF was increased 96-, 230-, and 267-fold, respectively, and ΔtolC or ΔacrEF mutants of S-AB-23, S-AB-38, and S-AB-73 showed the similar MICs to all tested antimicrobials as the ΔtolC mutant of Salmonella Typhimurium 14028s. Our data showed that constitutively over-expressed AcrAB working through TolC was the main resistance mechanism in ST14028s benzalkonium chloride resistance mutants. However, after AcrAB had been inactivated, benzalkonium chloride-resistant mutants could still be selected and constitutively over-expressed, AcrEF became the dominant efflux pump working through TolC and being responsible for the increasing antimicrobial resistance. These data indicated that different mechanisms existed for acrB and acrF constitutive over-expression. Since exposure to benzalkonium chloride may lead to Salmonella mutants with a decreased susceptibility to quinolones, which is currently one of the drugs of choice for the treatment of life-threatening salmonelosis, research into the pathogenesis and epidemiology of the benzalkonium chloride resistance mutants will be of increasing importance. PMID:23987991

  10. Salmonella Typhimurium and Salmonella Sofia: Growth in and Persistence on Eggs under Production and Retail Conditions

    PubMed Central

    McAuley, Catherine M.; Duffy, Lesley L.; Subasinghe, Nela; Hogg, Geoff; Coventry, John; Fegan, Narelle

    2015-01-01

    Salmonellosis in Australia has been linked to eggs and egg products with specific serotypes associated with outbreaks. We compared attachment to and survival on egg shells and growth in eggs of two Salmonella serotypes, an egg outbreak associated Salmonella Typhimurium and a non-egg-associated Salmonella enterica ssp. II 1,4,12,27:b:[e,n,x] (S. Sofia). Experiments were conducted at combinations of 4, 15, 22, 37 and 42°C. No significant differences occurred between the serotypes in maximum growth rates, which were significantly greater (P < 0.001) in egg yolk (0.427 log10 CFU/mL/h) compared to whole egg (0.312 log10 CFU/mL/h) and egg white (0.029 log10 CFU/mL/h). Attachment to egg shells varied by time (1 or 20 min) and temperature (4, 22 and 42°C), with S. Typhimurium isolates attaching at higher levels (P < 0.05) than S. Sofia after 1 min at 4°C and S. Typhimurium ATCC 14028 attaching at higher (P < 0.05) levels at 22°C. Survival on egg shells was not significantly different across isolates. Salmonella serotypes behaved similarly regarding growth in egg contents, attachment to egg shells and survival on eggs, indicating that other factors more likely contributed to reasons for S. Typhimurium being implicated in multiple egg-associated outbreaks. PMID:26539536

  11. Intracellular replication is essential for the virulence of Salmonella typhimurium.

    PubMed

    Leung, K Y; Finlay, B B

    1991-12-15

    Salmonella typhimurium is a facultative intracellular parasite, capable of penetrating, surviving, and multiplying within diverse eukaryotic cell types, including epithelial and phagocytic cells. We have been studying intracellular replication of S. typhimurium and found that it is essential in the pathogenesis of this bacterium. A total of 45,000 independent mini-Mu MudJ transposon mutants in S. typhimurium SL1344 were screened in Madin-Darby canine kidney (MDCK) epithelial cells with a beta-lactam, cefotaxime, to enrich for mutants defective for intracellular replication. Ten different auxotrophic (purine, pyrimidine, purine/methionine, and valine/isoleucine) and three prototrophic replication-defective mutants (Rep-) were identified. All Rep- mutants showed no differences in aerobic and anaerobic growth patterns, motility, serum sensitivity, mouse macrophage survival, iron uptake, and phosphate requirements. All Rep- mutants were unable to multiply inside MDCK, HeLa, and Caco-2 epithelial cells. When required nutrients for various auxotrophs were supplemented, auxotrophs then replicated inside MDCK cells. Although the parental strain multiplies in large vacuoles inside MDCK cells that distort the host cells, MDCK cells infected with the Rep- mutants appeared relatively normal and few bacteria were seen inside vacuoles. The purine auxotrophs and the three prototrophic Rep- mutants were highly attenuated in mice, and oral and intraperitoneal LD50 levels were 3 to 4 orders of magnitude higher than the wild type level. The three prototrophs were invasive and persisted in the murine organs such as livers and spleens for at least 3 weeks. Therefore, these prototrophic genes are needed for intracellular replication and are essential to the virulence of S. typhimurium. PMID:1763061

  12. Salmonella identification from foods in eight hours: A prototype study with Salmonella Typhimurium

    PubMed Central

    Koluman, A; Celik, G; Unlu, T

    2012-01-01

    Background and Objectives The significant rise in food borne infections is mainly caused by Campylobacter spp., Salmonella serovars and Verotoxigenic Escherichia coli. As the emerging food borne pathogens cause disease, more studies have been conducted for rapid detection of these pathogens. The combination of immunomagnetic separation and polymerase chain reaction (IMS-PCR) is the most accurate and rapid test preferred by almost every researcher. Fourier Transform Infrared Spectroscopy (FTIR) is preferred for being a new, user friendly and rapid technique in microbiological analyses. The main aim of this study is to detect application of IMS-FTIR for Salmonella identification from foods in a short time with a higher sensitivity. Materials and Methods Conventional Culture Technique (CC), IMS-CC, IMS-PCR and IMS-FTIR techniques were compared with each other for rapid detection in artificially contaminated minced beef with Salmonella Typhimurium, as of the 2nd, 4th and 8th hours of contamination. The method was evaluated in different food matrices and sensitivity, specifity and overall recovery was calculated. Results The results indicate that IMS-FTIR can detect S. Typhimurium as of the 8th hour with sensitivity of 95.6667, accuracy of 91.69329, false positive ratio of 0.04333 and overall recovery of 95.66%. Conclusion It can be suggested that the IMS-FTIR method is capable of detecting S.Typhimurium in a short time with lower cost. PMID:22783456

  13. Global Genomic Epidemiology of Salmonella enterica Serovar Typhimurium DT104.

    PubMed

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

    2016-04-01

    It has been 30 years since the initial emergence and subsequent rapid global spread of multidrug-resistant Salmonella entericaserovar 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 315S 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 Salmonellafrom 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

  14. Global regulation by CsrA in Salmonella typhimurium.

    PubMed

    Lawhon, Sara D; Frye, Jonathan G; Suyemoto, Mitsu; Porwollik, Steffen; McClelland, Michael; Altier, Craig

    2003-06-01

    CsrA is a regulator of invasion genes in Salmonella enterica serovar Typhimurium. To investigate the wider role of CsrA in gene regulation, we compared the expression of Salmonella genes in a csrA mutant with those in the wild type using a DNA microarray. As expected, we found that expression of Salmonella pathogenicity island 1 (SPI-1) invasion genes was greatly reduced in the csrA mutant, as were genes outside the island that encode proteins translocated into eukaryotic cells by the SPI-1 type III secretion apparatus. The flagellar synthesis operons, flg and fli, were also poorly expressed, and the csrA mutant was aflagellate and non-motile. The genes of two metabolic pathways likely to be used by Salmonella in the intestinal milieu also showed reduced expression: the pdu operon for utilization of 1,2-propanediol and the eut operon for ethanolamine catabolism. Reduced expression of reporter fusions in these two operons confirmed the microarray data. Moreover, csrA was found to regulate co-ordinately the cob operon for synthesis of vitamin B12, required for the metabolism of either 1,2-propanediol or ethanolamine. Additionally, the csrA mutant poorly expressed the genes of the mal operon, required for transport and use of maltose and maltodextrins, and had reduced amounts of maltoporin, normally a dominant protein of the outer membrane. These results show that csrA controls a number of gene classes in addition to those required for invasion, some of them unique to Salmonella, and suggests a co-ordinated bacterial response to conditions that exist at the site of bacterial invasion, the intestinal tract of a host animal. PMID:12791144

  15. Flagella-independent surface motility in Salmonella enterica serovar Typhimurium.

    PubMed

    Park, Sun-Yang; Pontes, Mauricio H; Groisman, Eduardo A

    2015-02-10

    Flagella are multiprotein complexes necessary for swimming and swarming motility. In Salmonella enterica serovar Typhimurium, flagella-mediated motility is repressed by the PhoP/PhoQ regulatory system. We now report that Salmonella can move on 0.3% agarose media in a flagella-independent manner when experiencing the PhoP/PhoQ-inducing signal low Mg(2+). This motility requires the PhoP-activated mgtA, mgtC, and pagM genes, which specify a Mg(2+) transporter, an inhibitor of Salmonella's own F1Fo ATPase, and a small protein of unknown function, respectively. The MgtA and MgtC proteins are necessary for pagM expression because pagM mRNA levels were lower in mgtA and mgtC mutants than in wild-type Salmonella, and also because pagM expression from a heterologous promoter rescued motility in mgtA and mgtC mutants. PagM promotes group motility by a surface protein(s), as a pagM-expressing strain conferred motility upon a pagM null mutant, and proteinase K treatment eliminated motility. The pagM gene is rarely found outside subspecies I of S. enterica and often present in nonfunctional allelic forms in organisms lacking the identified motility. Deletion of the pagM gene reduced bacterial replication on 0.3% agarose low Mg(2+) media but not in low Mg(2+) liquid media. Our findings define a form of motility that allows Salmonella to scavenge nutrients and to escape toxic compounds in low Mg(2+) semisolid environments. PMID:25624475

  16. Host Transmission of Salmonella enterica Serovar Typhimurium Is Controlled by Virulence Factors and Indigenous Intestinal Microbiota▿

    PubMed Central

    Lawley, Trevor D.; Bouley, Donna M.; Hoy, Yana E.; Gerke, Christine; Relman, David A.; Monack, Denise M.

    2008-01-01

    Transmission is an essential stage of a pathogen's life cycle and remains poorly understood. We describe here a model in which persistently infected 129X1/SvJ mice provide a natural model of Salmonella enterica serovar Typhimurium transmission. In this model only a subset of the infected mice, termed supershedders, shed high levels (>108 CFU/g) of Salmonella serovar Typhimurium in their feces and, as a result, rapidly transmit infection. While most Salmonella serovar Typhimurium-infected mice show signs of intestinal inflammation, only supershedder mice develop colitis. Development of the supershedder phenotype depends on the virulence determinants Salmonella pathogenicity islands 1 and 2, and it is characterized by mucosal invasion and, importantly, high luminal abundance of Salmonella serovar Typhimurium within the colon. Immunosuppression of infected mice does not induce the supershedder phenotype, demonstrating that the immune response is not the main determinant of Salmonella serovar Typhimurium levels within the colon. In contrast, treatment of mice with antibiotics that alter the health-associated indigenous intestinal microbiota rapidly induces the supershedder phenotype in infected mice and predisposes uninfected mice to the supershedder phenotype for several days. These results demonstrate that the intestinal microbiota plays a critical role in controlling Salmonella serovar Typhimurium infection, disease, and transmissibility. This novel model should facilitate the study of host, pathogen, and intestinal microbiota factors that contribute to infectious disease transmission. PMID:17967858

  17. Phosphorylation of Methyl-α-d-Glucopyranoside in Polymyxin B-Treated Salmonella typhimurium

    PubMed Central

    Teuber, Michael

    1969-01-01

    Phosphoenolpyruvate-dependent phosphorylation of methyl-α-d-glucopyranoside in Salmonella typhimurium is increased by the membrane active polypeptide antibiotic polymyxin B whereas active transport ability is abolished. PMID:4311870

  18. Flagella-independent surface motility in Salmonella enterica serovar Typhimurium

    PubMed Central

    Park, Sun-Yang; Pontes, Mauricio H.; Groisman, Eduardo A.

    2015-01-01

    Flagella are multiprotein complexes necessary for swimming and swarming motility. In Salmonella enterica serovar Typhimurium, flagella-mediated motility is repressed by the PhoP/PhoQ regulatory system. We now report that Salmonella can move on 0.3% agarose media in a flagella-independent manner when experiencing the PhoP/PhoQ-inducing signal low Mg2+. This motility requires the PhoP-activated mgtA, mgtC, and pagM genes, which specify a Mg2+ transporter, an inhibitor of Salmonella’s own F1Fo ATPase, and a small protein of unknown function, respectively. The MgtA and MgtC proteins are necessary for pagM expression because pagM mRNA levels were lower in mgtA and mgtC mutants than in wild-type Salmonella, and also because pagM expression from a heterologous promoter rescued motility in mgtA and mgtC mutants. PagM promotes group motility by a surface protein(s), as a pagM-expressing strain conferred motility upon a pagM null mutant, and proteinase K treatment eliminated motility. The pagM gene is rarely found outside subspecies I of S. enterica and often present in nonfunctional allelic forms in organisms lacking the identified motility. Deletion of the pagM gene reduced bacterial replication on 0.3% agarose low Mg2+ media but not in low Mg2+ liquid media. Our findings define a form of motility that allows Salmonella to scavenge nutrients and to escape toxic compounds in low Mg2+ semisolid environments. PMID:25624475

  19. Associations between host characteristics and antimicrobial resistance of Salmonella typhimurium.

    PubMed

    Ruddat, I; Tietze, E; Ziehm, D; Kreienbrock, L

    2014-10-01

    A collection of Salmonella Typhimurium isolates obtained from sporadic salmonellosis cases in humans from Lower Saxony, Germany between June 2008 and May 2010 was used to perform an exploratory risk-factor analysis on antimicrobial resistance (AMR) using comprehensive host information on sociodemographic attributes, medical history, food habits and animal contact. Multivariate resistance profiles of minimum inhibitory concentrations for 13 antimicrobial agents were analysed using a non-parametric approach with multifactorial models adjusted for phage types. Statistically significant associations were observed for consumption of antimicrobial agents, region type and three factors on egg-purchasing behaviour, indicating that besides antimicrobial use the proximity to other community members, health consciousness and other lifestyle-related attributes may play a role in the dissemination of resistances. Furthermore, a statistically significant increase in AMR from the first study year to the second year was observed. PMID:24300336

  20. Radiation-induced mutagenicity and lethality in Salmonella typhimurium

    SciTech Connect

    Isildar, M.; Bakale, G.

    1983-01-01

    The mutagenic and lethal effects of ionizing radiation on histidine-deficient auxotrophs of Salmonella typhimurium were studied to improve the understanding of radiation damage to DNA. The auxotrophs were divided into two groups - one which is sensitive to base-pair substitutions and another sensitive to frameshifts. These groups were composed of parent-daughter pairs in which the chemical mutagenicity enhancing plasmid, pKM101, is absent in the parent strain and present in the daughter. Co-60 ..gamma..-radiation and 250 kV x-rays were used to irradiate the bacteria. Irradiation of the frameshift - sensitive strains which carry the pKm101 plasmid doubled the absolute number of induced revertants whereas irradiation of the base-pair substitution sensitive strain which also carries the pKm101 plasmid produced nearly no change in the number of induced revertants. A nearly negligible effect on the mutation rate was observed for all parent strains. (ACR)

  1. Gene Transfer between Salmonella enterica Serovar Typhimurium inside Epithelial Cells

    PubMed Central

    Ferguson, Gayle C.; Heinemann, Jack A.; Kennedy, Martin A.

    2002-01-01

    Virulence and antibiotic resistance genes transfer between bacteria by bacterial conjugation. Conjugation also mediates gene transfer from bacteria to eukaryotic organisms, including yeast and human cells. Predicting when and where genes transfer by conjugation could enhance our understanding of the risks involved in the release of genetically modified organisms, including those being developed for use as vaccines. We report here that Salmonella enterica serovar Typhimurium conjugated inside cultured human cells. The DNA transfer from donor to recipient bacteria was proportional to the probability that the two types of bacteria occupied the same cell, which was dependent on viable and invasive bacteria and on plasmid tra genes. Based on the high frequencies of gene transfer between bacteria inside human cells, we suggest that such gene transfers occur in situ. The implications of gene transfer between bacteria inside human cells, particularly in the context of antibiotic resistance, are discussed. PMID:11914355

  2. THE POXR GENE OF SALMONELLA ENTERICA SEROVAR TYPHIMURIUM IS INVOLVED IN STRESS SURVIVAL AND SWINE COLONIZATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mutations in the poxR gene (STM4344; yjeA; poxA) of Salmonella enterica serovar Typhimurium (S. Typhimurium) have previously been shown to cause several phenotypic alterations including reduced pyruvate oxidase activity, virulence attenuation in the mouse model, and enhanced sensitivity to various ...

  3. Natural surface coating to inactivate Salmonella enterica Serovar Typhimurium and maintain quality of cherry tomatoes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of the present study were to investigate the effectiveness of zein-based coatings in reducing populations of Salmonella enterica serovar Typhimurium and preserving quality of cherry tomatoes. Tomatoes were inoculated with a cocktail of S. Typhimurium LT2 plus three mutants on the smoo...

  4. SURVIVAL OF SALMONELLA TYPHIMURIUM IN FOUR SOIL MICROCOSMS AS AFFECTED BY SOIL TYPE AND INCUBATION TEMPERATURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Survival of Salmonella typhimurium was determined in sterile and non-sterile microcosms in four soil series (Brooksville, Leeper, Marietta, and Ruston) held at 10, 15, 25 and 35 degrees C. Exponential linear destruction was observed for S. typhimurium in non-sterile soil stored at all temperatures....

  5. Mapping of prophage P22 in Salmonella typhimurium.

    PubMed

    Smith, S M; Stocker, B A

    1966-03-01

    Mutants resistant to phage P22 by virtue of roughness, due to mutation at rouB, were obtained in P22-lysogenic and nonlysogenic forms of two genetically marked lines of Salmonella typhimurium strain LT2. Crosses permuted in respect of the lysogeny or nonlysogeny of the rough metA tryB donor and of the rough adeC proA ile str-r acceptor line were then made, using the colicine factors colI and colE1 to obtain conjugation and recombination. When the donor was P22-lysogenic and the acceptor was nonlysogenic there was a great reduction in the yield of recombinants with the linked azi, pro, and gal alleles of the donor. In the cross of the nonlysogenic donor to the lysogenic acceptor the yield of recombinants with the pro+ donor allele was normal. In this cross all the recombinant clones with the pro+ allele from the donor were either nonlysogenic or mixed in respect of lysogeny, though homogeneous in respect of all other segregating characters. By contrast only one of 54 recombinants with the ile+, but not the pro+, donor allele was nonlysogenic. The results suggest that in lysogenic S. typhimurium strain LT2 prophage P22 is always or nearly always located on or in the chromosome very close to proA. PMID:18611473

  6. Oral Immunization of Mice with Killed Salmonella typhimurium Vaccine

    PubMed Central

    Waldman, Robert H.; Grunspan, Ruth; Ganguly, Rama

    1972-01-01

    A study was undertaken to assess the efficacy of oral, parenteral, and intraperitoneal immunization methods of administering killed Salmonella typhimurium vaccine to mice and to evaluate the effectiveness of single and multiple doses of the vaccine containing varied numbers of the killed bacteria. A further objective of this study was to evaluate the effect of adding substances to the vaccine to which have been ascribed “adjuvant” properties. The protection was estimated by isolation of bacteria from the spleen and feces after oral challenge of the mice with live S. typhimurium. The results showed that one or more doses of 1010 organisms given orally led to significant protection. This rate of protection increased proportionately with the number of doses up to 10 doses, which offered 100% protection. Streptomycin, when added to multiple doses of 109 or more organisms given orally, increased the degree of protection, but beryllium sulfate and pertussis vaccine did not. Although multiple doses afforded similar systemic protection by all three routes of immunization, oral immunization yielded significantly greater local protection than that observed after subcutaneous or intraperitoneal immunization. PMID:4564152

  7. Regulation of Salmonella typhimurium ilvYC genes.

    PubMed

    Blazey, D L; Burns, R O

    1984-09-01

    The Salmonella typhimurium LT2 ilvYC genes were studied by fusion of each gene to the Escherichia coli K-12 galK gene. The expression of ilvY and ilvC could then be determined by measurement of the galK-encoded galactokinase enzyme. The promoter for ilvC, pC, was located by this technique to a 0.42-kilobase BglII-EcoRI fragment of the S. typhimurium ilvGEDAYC gene cluster. This sequence was completely sufficient for alpha-acetohydroxyacid-inducible galK expression. The ilvY gene was located within a 1.0-kilobase XhoI-SalI fragment. ilvY gene expression was constitutive with respect to ilv-specific control signals. The ilvY gene was transcribed in the same direction as the other two transcriptional units in the ilvGEDAYC gene cluster, ilvGEDA and ilvC. Transcription of the ilvC gene was completely dependent upon the activity of its own promoter, pC, and independent from transcription of the ilvY gene. The role of the intervening region between ilvY and ilvC in regulation of ilvC expression was explored. PMID:6090400

  8. Activation of a new proline transport system in Salmonella typhimurium.

    PubMed

    Ekena, K; Liao, M K; Maloy, S

    1990-06-01

    Proline uptake can be mediated by three different transport systems in wild-type Salmonella typhimurium: a high-affinity proline transport system encoded by the putP gene and two glycine-betaine transport systems with a low affinity for proline encoded by the proP and proU genes. However, only the PutP permease transports proline well enough t allow growth on proline as a sole carbon or nitrogen source. By selecting for mutations that allow a putP mutant to grow on proline as a sole nitrogen source, we isolated mutants (designated proZ) that appeared to activate a cryptic proline transport system. These mutants enhanced the transport of proline and proline analogs but did not require the function of any of the known proline transport genes. The mutations mapped between 75 and 77.5 min on the S. typhimurium linkage map. Proline transport by the proZ mutants was competitively inhibited by isoleucine and leucine, which suggests that the ProZ phenotype may be due to unusual mutations that alter the substrate specificity of the branched-chain amino acid transport system encoded by the liv genes. PMID:2160931

  9. New Salmonella typhimurium mutants with altered outer membrane permeability.

    PubMed Central

    Sukupolvi, S; Vaara, M; Helander, I M; Viljanen, P; Mäkelä, P H

    1984-01-01

    We describe three new classes of Salmonella typhimurium mutants with increased sensitivity to hydrophobic agents. In contrast to many previously described mutants, the phage sensitivity pattern of these mutants did not give any indication of defective lipopolysaccharide. Furthermore, they had no detectable changes in their phospholipid or outer membrane protein composition, and their growth rate and cell morphology were normal. Class B mutants were nearly as sensitive to novobiocin, fusidic acid, erythromycin, rifampin, and clindamycin as are deep rough (heptoseless) mutants; in addition they were sensitive to methicillin, penicillin (to which heptoseless mutants are resistant), gentian violet, and anionic and cationic detergents. Class A and C mutants had less sensitive, but characteristic phenotypes. None of the three classes were sensitive to serum bactericidal action. The class B mutation mapped between map positions 7 and 11 on the S. typhimurium chromosome, and the class C mutation mapped between positions 5 and 7. The map position for the class A mutation remained undefined, but it was separate from the class B and C mutations and, like those, did not correspond to any gene loci known to participate in the synthesis of major outer membrane constituents. Images PMID:6378889

  10. Prevalence and antibiotic resistance of Salmonella Enteritidis and Salmonella Typhimurium in raw chicken meat at retail markets in Malaysia.

    PubMed

    Thung, T Y; Mahyudin, N A; Basri, D F; Wan Mohamed Radzi, C W J; Nakaguchi, Y; Nishibuchi, M; Radu, S

    2016-08-01

    Salmonellosis is one of the major food-borne diseases in many countries. This study was carried out to determine the occurrence of Salmonella spp., Salmonella Enteritidis, and Salmonella Typhimurium in raw chicken meat from wet markets and hypermarkets in Selangor, as well as to determine the antibiotic susceptibility profile of S. Enteritidis and S. Typhimurium. The most probable number (MPN) in combination with multiplex polymerase chain reaction (mPCR) method was used to quantify the Salmonella spp., S. Enteritidis, and S. Typhimurium in the samples. The occurrence of Salmonella spp., S. Enteritidis, and S. Typhimurium in 120 chicken meat samples were 20.80%, 6.70%, and 2.50%, respectively with estimated quantity varying from <3 to 15 MPN/g. The antibiogram testing revealed differential multi-drug resistance among S. Enteritidis and S. Typhimurium isolates. All the isolates were resistance to erythromycin, penicillin, and vancomycin whereas sensitivity was recorded for Amoxicillin/Clavulanic acid, Gentamicin, Tetracycline, and Trimethoprim. Our findings demonstrated that the retail chicken meat could be a source of multiple antimicrobial-resistance Salmonella and may constitute a public health concern in Malaysia. PMID:27118863

  11. T-2 toxin induced Salmonella Typhimurium intoxication results in decreased Salmonella numbers in the cecum contents of pigs, despite marked effects on Salmonella-host cell interactions.

    PubMed

    Verbrugghe, Elin; Vandenbroucke, Virginie; Dhaenens, Maarten; Shearer, Neil; Goossens, Joline; De Saeger, Sarah; Eeckhout, Mia; D'Herde, Katharina; Thompson, Arthur; Deforce, Dieter; Boyen, Filip; Leyman, Bregje; Van Parys, Alexander; De Backer, Patrick; Haesebrouck, Freddy; Croubels, Siska; Pasmans, Frank

    2012-01-01

    The mycotoxin T-2 toxin and Salmonella Typhimurium infections pose a significant threat to human and animal health. Interactions between both agents may result in a different outcome of the infection. Therefore, the aim of the presented study was to investigate the effects of low and relevant concentrations of T-2 toxin on the course of a Salmonella Typhimurium infection in pigs. We showed that the presence of 15 and 83 μg T-2 toxin per kg feed significantly decreased the amount of Salmonella Typhimurium bacteria present in the cecum contents, and a tendency to a reduced colonization of the jejunum, ileum, cecum, colon and colon contents was noticed. In vitro, proteomic analysis of porcine enterocytes revealed that a very low concentration of T-2 toxin (5 ng/mL) affects the protein expression of mitochondrial, endoplasmatic reticulum and cytoskeleton associated proteins, proteins involved in protein synthesis and folding, RNA synthesis, mitogen-activated protein kinase signaling and regulatory processes. Similarly low concentrations (1-100 ng/mL) promoted the susceptibility of porcine macrophages and intestinal epithelial cells to Salmonella Typhimurium invasion, in a SPI-1 independent manner. Furthermore, T-2 toxin (1-5 ng/mL) promoted the translocation of Salmonella Typhimurium over an intestinal porcine epithelial cell monolayer. Although these findings may seem in favour of Salmonella Typhimurium, microarray analysis showed that T-2 toxin (5 ng/mL) causes an intoxication of Salmonella Typhimurium, represented by a reduced motility and a downregulation of metabolic and Salmonella Pathogenicity Island 1 genes. This study demonstrates marked interactions of T-2 toxin with Salmonella Typhimurium pathogenesis, resulting in bacterial intoxication. PMID:22440148

  12. A comparison between longitudinal shedding patterns of Salmonella Typhimurium and Salmonella Dublin on dairy farms.

    PubMed

    Kirchner, M; McLaren, I; Clifton-Hadley, F A; Liebana, E; Wales, A D; Davies, R H

    2012-08-25

    Salmonella in cattle herds may behave as epidemic or endemic infections. An intensive longitudinal sampling study across all management groups and ages on six dairy farms in the UK was used to examine patterns of Salmonella shedding, following the prior identification of either Salmonella Dublin (SD) (three farms) or Salmonella Typhimurium (ST) (three farms) on the premises in the context of clinical salmonellosis. Individual faeces, pooled faeces and environmental samples (total 5711 samples), taken approximately every six weeks for 15-24 weeks, were cultured for Salmonella. SD was detected at low frequency (on any visit, 0.5-18.3 per cent of samples positive) and most consistently in calves. By contrast, ST was isolated at higher frequency (on any visit, 6.8-75 per cent of samples positive), and in higher numbers, up to 10(7) cfu/g faeces. Significantly more samples from calves were positive for ST than were positive for SD (50.6 per cent v 3.1 per cent; P < 0.001), which was also true for milking cows (46.3 per cent v 4.4 per cent; P < 0.001). The differences could help to explain the different patterns of bovine infection classically associated with these two serovars in the UK. No consistent effect upon shedding was seen among the ST-infected herds following vaccination. PMID:22859413

  13. Molecular fingerprinting of Salmonella enterica subsp. enterica Typhimurium and Salmonella enterica subsp. enterica derby isolated from tropical seafood in South India.

    PubMed

    Kumar, Rakesh; Surendran, P K; Thampuran, Nirmala

    2008-09-01

    Salmonella enterica subsp. enterica Typhimurium and Salmonella enterica subsp. enterica Derby strains isolated from different seafood were genotyped by PCR-ribotyping and ERIC-PCR assays. This study has ascertained the genetic relatedness among serovars prevalent in tropical seafood. PCR-ribotyping exhibited genetic variation in both Salmonella serovars, and ribotype profile (II) was most predominant, which was observed in 10/18 of Salmonella enterica subsp. enterica Typhimurium and 7/17 Salmonella enterica subsp. enterica Derby isolates. Cluster analysis of ERIC-PCR for Salmonella enterica subsp. enterica Typhimurium strains exhibited nine different banding patterns and four strains showed >95% genetic homology within the cluster pairs. ERIC-PCR produced more genetic variations in Salmonella enterica subsp. enterica Typhimurium; nevertheless, both methods were found to be comparable for Salmonella enterica subsp. enterica Derby isolates. Discrimination index of PCR-ribotyping for Salmonella enterica subsp. enterica Typhimurium isolates was obtained at 0.674 and index value 0.714 was observed for Salmonella enterica subsp. enterica Derby strains. Molecular fingerprinting investigation highlighted the hypothesis of diverse routes of Salmonella contamination in seafood as multiple clones of Salmonella enterica subsp. enterica Typhimurium and Salmonella enterica subsp. enterica Derby were detected in same or different seafood throughout the study period. PMID:18480975

  14. Tetracycline promotes the expression of ten fimbrial operons in specific Salmonella enterica serovar Typhimurium isolates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multidrug-resistant (MDR) Salmonella is associated with increased morbidity in humans and presents an important food safety concern. Antibiotic resistance among isolates of Salmonella enterica serovar Typhimurium has become especially prevalent as over 27 per cent of isolates from humans in the Unit...

  15. Hydrogen-Stimulated carbon acquisition and conservation in salmonella enterica serovar typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Typhimurium can utilize molecular hydrogen for growth and amino acid transport during anaerobic growth. Via microarray we identified H2 gas-affected gene expression changes in Salmonella. Addition of H2 caused altered expression of 965 genes; 176 genes were H2-up-regulate...

  16. SUSCEPTIBILITY TO SALMONELLA TYPHIMURIUM INFECTION INCREASES WITH AGE IN C57BL/6 MICE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enterocolitis due to Salmonella infection is the most common cause of death from food borne illnesses in the U.S. Salmonella typhimurium (ST) is most frequently associated with this disease. ST infection can be particularly severe in the elderly. However, a well-defined animal model to study the eff...

  17. Antibiotics induce the expression of attachment genes in specific isolates of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    More than 27 percent of Salmonella enterica serovar Typhimurium isolates from humans in the United States are resistant to three or more antibiotics. This presents an important food safety concern as multidrug-resistant (MDR) Salmonella is associated with increased morbidity in humans. It has been...

  18. Signatures of Adaptation in Human Invasive Salmonella Typhimurium ST313 Populations from Sub-Saharan Africa

    PubMed Central

    Okoro, Chinyere K.; Barquist, Lars; Connor, Thomas R.; Harris, Simon R.; Clare, Simon; Stevens, Mark P.; Arends, Mark J.; Hale, Christine; Kane, Leanne; Pickard, Derek J.; Hill, Jennifer; Harcourt, Katherine; Parkhill, Julian; Dougan, Gordon; Kingsley, Robert A.

    2015-01-01

    Two lineages of Salmonella enterica serovar Typhimurium (S. Typhimurium) of multi-locus sequence type ST313 have been linked with the emergence of invasive Salmonella disease across sub-Saharan Africa. The expansion of these lineages has a temporal association with the HIV pandemic and antibiotic usage. We analysed the whole genome sequence of 129 ST313 isolates representative of the two lineages and found evidence of lineage-specific genome degradation, with some similarities to that observed in S. Typhi. Individual ST313 S. Typhimurium isolates exhibit a distinct metabolic signature and modified enteropathogenesis in both a murine and cattle model of colitis, compared to S. Typhimurium outside of the ST313 lineages. These data define phenotypes that distinguish ST313 isolates from other S. Typhimurium and may represent adaptation to a distinct pathogenesis and lifestyle linked to an-immuno-compromised human population. PMID:25803844

  19. Detection of Salmonella spp, Salmonella Enteritidis and Typhimurium in naturally infected broiler chickens by a multiplex PCR-based assay

    PubMed Central

    Paião, F.G.; Arisitides, L.G.A.; Murate, L.S.; Vilas-Bôas, G.T.; Vilas-Boas, L.A.; Shimokomaki, M.

    2013-01-01

    The presence of Salmonella in the intestinal tract, on the chickens skin and among their feathers, may cause carcasses contamination during slaughtering and processing and possibly it is responsible by the introduction of this microorganism in the slaughterhouses. A rapid method to identify and monitor Salmonella and their sorovars in farm is becoming necessary. A pre-enriched multiplex polymerase chain reaction (m-PCR) assay employing specific primers was developed and used to detect Salmonella at the genus level and to identify the Salmonella enterica serovar Enteritidis (S. Enteritidis) and Salmonella enterica serovar Typhimurium (S. Typhimurium) in broiler chicken swab samples. The method was validated by testing DNA extract from 90 fresh culture cloacal swab samples from poultry chicken cultured in phosphate buffer peptone water at 37 °C for 18 h. The final results showed the presence of Salmonella spp. in 25% of samples, S. Enteritidis was present in 12% of the Salmonella-positive samples and S. Typhimurium in 3% of the samples. The m-PCR assay developed in this study is a specific and rapid alternative method for the identification of Salmonella spp. and allowed the observation of specific serovar contamination in the field conditions within the locations where these chickens are typically raised. PMID:24159281

  20. Intra-continental spread of human invasive Salmonella Typhimurium pathovariants in sub-Saharan Africa

    PubMed Central

    Okoro, Chinyere K.; Kingsley, Robert A.; Connor, Thomas R.; Harris, Simon R.; Parry, Christopher M.; Al-Mashhadani, Manar N; Kariuki, Samuel; Msefula, Chisomo L.; Gordon, Melita A.; de Pinna, Elizabeth; Wain, John; Heyderman, Robert S.; Obaro, Stephen; Alonso, Pedro L.; Mandomando, Inacio; MacLennan, Calman A.; Tapia, Milagritos D.; Levine, Myron M.; Tennant, Sharon M; Parkhill, Julian; Dougan, Gordon

    2012-01-01

    A highly invasive form of non-typhoidal Salmonella (iNTS) disease has been recently documented in many countries in sub-Saharan Africa. The most common Salmonella enterica serovar causing this disease is Typhimurium. We applied whole-genome sequence-based phylogenetic methods to define the population structure of sub-Saharan African invasive Salmonella Typhimurium and compared these to global Salmonella Typhimurium isolates. Notably, the vast majority of sub-Saharan invasive Salmonella Typhimurium fell within two closely-related, highly-clustered phylogenetic lineages that we estimate emerged independently ~52 and ~35 years ago, in close temporal association with the current HIV pandemic. Clonal replacement of isolates of lineage I by lineage II was potentially influenced by the use of chloramphenicol for the treatment of iNTS disease. Our analysis suggests that iNTS disease is in part an epidemic in sub-Saharan Africa caused by highly related Salmonella Typhimurium lineages that may have occupied new niches associated with a compromised human population and antibiotic treatment. PMID:23023330

  1. 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. PMID:26678129

  2. Egg contamination by Salmonella serovar enteritidis following vaccination with Delta-aroA Salmonella serovar typhimurium.

    PubMed

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

    2001-02-01

    The efficacy of an aroA Salmonella serovar typhimurium modified live vaccine to decrease internal egg contamination after oral challenge of hens with egg-contaminating Salmonella serovar enteritidis was assessed. Challenge was with a mixed phenotype of S. enteritidis that had virulence characteristics previously associated with enhanced oral invasiveness and egg contamination in chickens. Immunized birds had fewer positive ovary/oviduct pools and lower cfu g(-1) cecal contents than did non-immunized birds, but the differences were not significant. The number of positive intestinal (duodenum, jejunum, ileum) and organ (spleen, kidney, liver) pools following challenge from each treatment group were equivalent. Most importantly, immunization did not decrease egg contamination. These results suggest that the ability of modified live vaccines to reduce internal egg contamination by S. serovar enteritidis can be assessed using characterized strains for challenge. PMID:11166998

  3. Alternate routes of invasion may affect pathogenesis of Salmonella typhimurium in swine.

    PubMed Central

    Fedorka-Cray, P J; Kelley, L C; Stabel, T J; Gray, J T; Laufer, J A

    1995-01-01

    Transmission of Salmonella typhimurium in swine is traditionally believed to occur by the fecal-oral route, with invasion through the intestinal wall and Peyer's patches. However, involvement of the upper respiratory tract may be equally important. An esophagotomy was performed on 6- to 8-week-old pigs. Esophagotomized pigs were challenged intranasally with 10(9) CFU of S. typhimurium cells and necropsied at 3, 6, 12, and 18 h postinoculation (p.i.). By 3 h p.i., S. typhimurium was recovered from cecum, colon, head, and thoracic tissues and from the middle ileum involving a large number of Peyer's patches. The ileocolic lymph nodes and ileocolic junction were not positive for S. typhimurium until 6 and 12 h p.i., respectively. Additional pigs were inoculated transthoracically with 10(9) CFU of S. typhimurium and necropsied at 3 and 18 h p.i. By 3 h p.i., all tissues were positive for S. typhimurium. Tonsil explants seeded with 10(9) CFU of S. typhimurium indicated that within 6 h p.i., S. typhimurium was located within the tonsilar crypts. These data show that after intranasal inoculation, S. typhimurium rapidly appears in the gut tissues and suggest that the tonsils and lung may be important sites for invasion and dissemination of Salmonella species. PMID:7790082

  4. Stress Response of Salmonella enterica Serovar Typhimurium to Acidified Nitrite

    PubMed Central

    Mühlig, Anna; Behr, Jürgen; Scherer, Siegfried

    2014-01-01

    The antimicrobial action of the curing agent sodium nitrite (NaNO2), which is added as a preservative to raw meat products, depends on its conversion to nitric oxide and other reactive nitrogen species under acidic conditions. In this study, we used RNA sequencing to analyze the acidified-NaNO2 shock and adaptive responses of Salmonella enterica serovar Typhimurium, a frequent contaminant in raw meat, considering parameters relevant for the production of raw-cured sausages. Upon a 10-min exposure to 150 mg/liter NaNO2 in LB (pH 5.5) acidified with lactic acid, genes involved in nitrosative-stress protection, together with several other stress-related genes, were induced. In contrast, genes involved in translation, transcription, replication, and motility were downregulated. The induction of stress tolerance and the reduction of cell proliferation obviously promote survival under harsh acidified-NaNO2 stress. The subsequent adaptive response was characterized by upregulation of NsrR-regulated genes and iron uptake systems and by downregulation of genes involved in anaerobic respiratory pathways. Strikingly, amino acid decarboxylase systems, which contribute to acid tolerance, displayed increased transcript levels in response to acidified NaNO2. The induction of systems known to be involved in acid resistance indicates a nitrite-mediated increase in the level of acid stress. Deletion of cadA, which encodes lysine decarboxylase, resulted in increased sensitivity to acidified NaNO2. Intracellular pH measurements using a pH-sensitive green fluorescent protein (GFP) variant showed that the cytoplasmic pH of S. Typhimurium in LB medium (pH 5.5) is decreased upon the addition of NaNO2. This study provides the first evidence that intracellular acidification is an additional antibacterial mode of action of acidified NaNO2. PMID:25107963

  5. A comparison of cecal colonization of Salmonella enterica serotype Typhimurium in white leghorn chicks and Salmonella-resistant mice

    PubMed Central

    Sivula, Christine P; Bogomolnaya, Lydia M; Andrews-Polymenis, Helene L

    2008-01-01

    Background Salmonellosis is one of the most important bacterial food borne illnesses worldwide. A major source of infection for humans is consumption of chicken or egg products that have been contaminated with Salmonella enterica serotype Typhimurium, however our knowledge regarding colonization and persistence factors in the chicken is small. Results We compared intestinal and systemic colonization of 1-week-old White Leghorn chicks and Salmonella-resistant CBA/J mice during infection with Salmonella enterica serotype Typhimurium ATCC14028, one of the most commonly studied isolates. We also studied the distribution of wild type serotype Typhimurium ATCC14028 and an isogenic invA mutant during competitive infection in the cecum of 1-week-old White Leghorn chicks and 8-week-old CBA/J mice. We found that although the systemic levels of serotype Typhimurium in both infected animal models are low, infected mice have significant splenomegaly beginning at 15 days post infection. In the intestinal tract itself, the cecal contents are the major site for recovery of serotype Typhimurium in the cecum of 1-week-old chicks and Salmonella-resistant mice. Additionally we show that only a small minority of Salmonellae are intracellular in the cecal epithelium of both infected animal models, and while SPI-1 is important for successful infection in the murine model, it is important for association with the cecal epithelium of 1-week-old chicks. Finally, we show that in chicks infected with serotype Typhimurium at 1 week of age, the level of fecal shedding of this organism does not reflect the level of cecal colonization as it does in murine models. Conclusion In our study, we highlight important differences in systemic and intestinal colonization levels between chick and murine serotype Typhimurium infections, and provide evidence that suggests that the role of SPI-1 may not be the same during colonization of both animal models. PMID:18922185

  6. House Sparrows Do Not Constitute a Significant Salmonella Typhimurium Reservoir across Urban Gradients in Flanders, Belgium

    PubMed Central

    Rouffaer, Lieze Oscar; Lens, Luc; Haesendonck, Roel; Teyssier, Aimeric; Hudin, Noraine Salleh; Strubbe, Diederik; Haesebrouck, Freddy; Pasmans, Frank; Martel, An

    2016-01-01

    In recent decades major declines in urban house sparrow (Passer domesticus) populations have been observed in north-western European cities, whereas suburban and rural house sparrow populations have remained relatively stable or are recovering from previous declines. Differential exposure to avian pathogens known to cause epidemics in house sparrows may in part explain this spatial pattern of declines. Here we investigate the potential effect of urbanization on the development of a bacterial pathogen reservoir in free-ranging house sparrows. This was achieved by comparing the prevalence of Salmonella enterica subspecies enterica serotype Typhimurium in 364 apparently healthy house sparrows captured in urban, suburban and rural regions across Flanders, Belgium between September 2013 and March 2014. In addition 12 dead birds, received from bird rescue centers, were necropsied. The apparent absence of Salmonella Typhimurium in fecal samples of healthy birds, and the identification of only one house sparrow seropositive for Salmonella spp., suggests that during the winter of 2013–2014 these birds did not represent any considerable Salmonella Typhimurium reservoir in Belgium and thus may be considered naïve hosts, susceptible to clinical infection. This susceptibility is demonstrated by the isolation of two different Salmonella Typhimurium strains from two of the deceased house sparrows: one DT99, typically associated with disease in pigeons, and one DT195, previously associated with a passerine decline. The apparent absence (prevalence: <1.3%) of a reservoir in healthy house sparrows and the association of infection with clinical disease suggests that the impact of Salmonella Typhimurium on house sparrows is largely driven by the risk of exogenous exposure to pathogenic Salmonella Typhimurium strains. However, no inference could be made on a causal relationship between Salmonella infection and the observed house sparrow population declines. PMID:27168186

  7. Probiotic bacteria reduce salmonella typhimurium intestinal colonization by competing for iron.

    PubMed

    Deriu, Elisa; Liu, Janet Z; Pezeshki, Milad; Edwards, Robert A; Ochoa, Roxanna J; Contreras, Heidi; Libby, Stephen J; Fang, Ferric C; Raffatellu, Manuela

    2013-07-17

    Host inflammation alters the availability of nutrients such as iron to limit microbial growth. However, Salmonella enterica serovar Typhimurium thrives in the inflamed gut by scavenging for iron with siderophores. By administering Escherichia coli strain Nissle 1917, which assimilates iron by similar mechanisms, we show that this nonpathogenic bacterium can outcompete and reduce S. Typhimurium colonization in mouse models of acute colitis and chronic persistent infection. This probiotic activity depends on E. coli Nissle iron acquisition, given that mutants deficient in iron uptake colonize the intestine but do not reduce S. Typhimurium colonization. Additionally, the ability of E. coli Nissle to overcome iron restriction by the host protein lipocalin 2, which counteracts some siderophores, is essential, given that S. Typhimurium is unaffected by E. coli Nissle in lipocalin 2-deficient mice. Thus, iron availability impacts S. Typhimurium growth, and E. coli Nissle reduces S. Typhimurium intestinal colonization by competing for this limiting nutrient. PMID:23870311

  8. Effect of Chitosan on Salmonella Typhimurium in Broiler Chickens

    PubMed Central

    Menconi, Anita; Pumford, Neil R.; Morgan, Marion J.; Bielke, Lisa R.; Kallapura, Gopala; Latorre, Juan D.; Wolfenden, Amanda D.; Hernandez-Velasco, Xochitl; Hargis, Billy M.

    2014-01-01

    Abstract Public concern with the incidence of antibiotic-resistant bacteria, particularly among foodborne pathogens such as Salmonella, has been challenging the poultry industry to find alternative means of control. The purposes of the present study were to evaluate in vitro and in vivo effects of chitosan on Salmonella enterica serovar Typhimurium (ST) infection in broiler chicks. For in vitro crop assay experiments, tubes containing feed, water, and ST were treated with either saline as a control or 0.2% chitosan. The entire assay was repeated in three trials. In two independent in vivo trials, 40 broiler chicks were assigned to an untreated control diet or dietary treatment with 0.2% chitosan for 7 days (20 broiler chicks/treatment). At day 4, chicks were challenged with 2×105 colony-forming units (CFU) ST/bird. In a third in vivo trial, 100 broiler chicks were assigned to untreated control diet or dietary treatment with 0.2% chitosan for 10 days (50 broiler chicks/treatment) to evaluate ST horizontal transmission. At day 3, 10 birds were challenged with 105 CFU ST/bird, and the remaining nonchallenged birds (n=40) were kept in the same floor pen. In all three in vitro trials, 0.2% chitosan significantly reduced total CFU of ST at 0.5 and 6 h postinoculation compared with control (p<0.05). In two in vivo trials, at 7 days, dietary 0.2% chitosan significantly reduced total CFU of recovered ST in the ceca in both experiments. Dietary 0.2% chitosan significantly reduced total ST CFU recovered in the ceca of horizontally challenged birds in the third in vivo trial. Chitosan at 0.2% significantly reduced the CFU of recovered ST in vitro and in vivo, proving to be an alternative tool to reduce crop, ceca, and consequently carcass ST contamination as well as decreasing the amount of ST shed to the environment. PMID:24237042

  9. Novel surface antigen based impedimetric immunosensor for detection of Salmonella typhimurium in water and juice samples.

    PubMed

    Mutreja, Ruchi; Jariyal, Monu; Pathania, Preeti; Sharma, Arunima; Sahoo, D K; Suri, C Raman

    2016-11-15

    A specific surface antigen, OmpD has been reported first time as a surface biomarker in the development of selective and sensitive immunosensor for detecting Salmonella typhimurium species. The OmpD surface antigen extraction was done from Salmonella typhimurium serovars, under the optimized growth conditions for its expression. Anti-OmpD antibodies were generated and used as detector probe in immunoassay format on graphene-graphene oxide (G-GO) modified screen printed carbon electrodes. The water samples were spiked with standard Salmonella typhimurium cells, and detection was done by measuring the change in impedimetric response of developed immunosensor to know the concentration of serovar Salmonella typhimurium. The developed immunosensor was able to specifically detect S. typhimurium in spiked water and juice samples with a sensitivity upto 10(1)CFUmL(-1), with high selectivity and very low cross-reactivity with other strains. This is the first report on the detection of Salmonella typhimurum species using a specific biomarker, OmpD. The developed technique could be very useful for the detection of nontyphoidal Salmonellosis and is also important from an epidemiological point of view. PMID:27261886

  10. Invasive Salmonella Typhimurium ST313 with Naturally Attenuated Flagellin Elicits Reduced Inflammation and Replicates within Macrophages

    PubMed Central

    Ramachandran, Girish; Perkins, Darren J.; Schmidlein, Patrick J.; Tulapurkar, Mohan E.; Tennant, Sharon M.

    2015-01-01

    Invasive non-typhoidal Salmonella (iNTS) are an important cause of septicemia in children under the age of five years in sub-Saharan Africa. A novel genotype of Salmonella enterica subsp. enterica serovar Typhimurium (multi-locus sequence type [ST] 313) circulating in this geographic region is genetically different to from S. Typhimurium ST19 strains that are common throughout the rest of the world. S. Typhimurium ST313 strains have acquired pseudogenes and genetic deletions and appear to be evolving to become more like the typhoidal serovars S. Typhi and S. Paratyphi A. Epidemiological and clinical data show that S. Typhimurium ST313 strains are clinically associated with invasive systemic disease (bacteremia, septicemia, meningitis) rather than with gastroenteritis. The current work summarizes investigations of the broad hypothesis that S. Typhimurium ST313 isolates from Mali, West Africa, will behave differently from ST19 isolates in various in vitro assays. Here, we show that strains of the ST313 genotype are phagocytosed more efficiently and are highly resistant to killing by macrophage cell lines and primary mouse and human macrophages compared to ST19 strains. S. Typhimurium ST313 strains survived and replicated within different macrophages. Infection of macrophages with S. Typhimurium ST19 strains resulted in increased apoptosis and higher production of proinflammatory cytokines, as measured by gene expression and protein production, compared to S. Typhimurium ST313 strains. This difference in proinflammatory cytokine production and cell death between S. Typhimurium ST19 and ST313 strains could be explained, in part, by an increased production of flagellin by ST19 strains. These observations provide further evidence that S. Typhimurium ST313 strains are phenotypically different to ST19 strains and instead share similar pathogenic characteristics with typhoidal Salmonella serovars. PMID:25569606

  11. Regulatory implications of Ames' mutagenicity assay using Salmonella typhimurium

    SciTech Connect

    Jackson, B.A.; Pertel, R.

    1986-07-01

    Interpretive difficulties can be expected when molecular biology and modern genetics are applied to the safety evaluation of chemicals. Experience, in a regulatory setting, with evaluating the results of short term tests, such as Ames' mutagenicity assay using Salmonella typhimurium (Ames' assay), shows that the traditional toxicological paradigm for interpreting and evaluating the results of such tests is less than adequate. The considerable importance of a negative test outcome to the public health as well as to the course of the commercial development of a potentially useful chemical places special demands on both the investigator and the regulatory reviewer for an understanding of Ames' assay. The adequate design, conduct, interpretation, and evaluation of the outcomes of this assay require a knowledge of the chemical properties of the test agent, an understanding of the scientific basis of the test, and an appreciation of the extent to which modifications of the assay can alter the outcome. The investigator and the regulatory reviewer use the same considerations to determine the adequacy of the test design and of the test results. However, a fundamental difference exists between how they interpret results and how they view the outcome. Results from a study comparing activation systems from food animal and laboratory animal sources are used to illustrate the complexity of using safety data from a genetic test. A framework is developed to suggest how to accommodate the points of view of the investigator and the regulatory reviewer in evaluating these data.

  12. Zinc concentration and survival in rats infected with Salmonella typhimurium.

    PubMed Central

    Tocco-Bradley, R; Kluger, M J

    1984-01-01

    Percent survival was measured in male rats injected intravenously with live Salmonella typhimurium when plasma and tissue zinc levels were manipulated. Alzet pumps implanted intraperitoneally infused zinc gluconate or sodium gluconate (controls) from the onset of infection to 72 h postinfection. Plasma and tissue zinc levels were manipulated by infusing (i) 180 micrograms of Zn per h to achieve supranormal plasma and tissue zinc concentrations, (ii) 120 micrograms of Zn per h to prevent the infection-induced fall and to maintain plasma zinc levels at noninfection levels while raising tissue levels above that of infected controls, and (iii) 30 micrograms of Zn per h to increase tissue zinc levels while allowing the infection-induced decrease in plasma zinc. Preventing the fall in plasma zinc while raising liver zinc to supranormal levels enhanced rather than reduced percent survival; raising plasma and liver zinc to supranormal levels returned survival to control levels. Loading the liver with an excess of zinc without changing plasma zinc (30 micrograms of Zn per h) did not increase percent survival in the infected host. Pretreatment or administration of zinc at the time of infection led to increased percent survival compared with administration of zinc 4 h after the onset of infection. PMID:6746092

  13. Chlorine inactivation of non-resistant and antibiotic resistant strains of Salmonella Typhimurium isolated from chicken carcasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to test the hypothesis that strains of Salmonella Typhimurium that are resistant to antibiotics are more resistant to chlorine than strains of S. Typhimurium that are not resistant to antibiotics. To test this hypothesis, strains (n = 16) of S. Typhimurium with four antibiotic...

  14. Parenteral administration of attenuated Salmonella Typhimurium ΔznuABC is protective against salmonellosis in piglets.

    PubMed

    Ruggeri, J; Pesciaroli, M; Gaetarelli, B; Scaglione, F E; Pregel, P; Ammendola, S; Battistoni, A; Bollo, E; Alborali, G L; Pasquali, P

    2014-07-01

    A major cause of salmonellosis in humans is the contamination of pork products. Infection in pigs can be controlled using bio-security programs, but they are not sufficient in countries where a high level of infection is recorded. In this context, the use of vaccines can represent a valid supplementary method of control. Recently, we have demonstrated that an attenuated strain of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium ΔznuABC) is protective against systemic and enteric salmonellosis in mouse and pig infection models, candidating this strain as an oral attenuated vaccine. In this study, we compared the efficacy of this attenuated Salmonella Typhimurium strain when administered orally or parenterally. Furthermore, in order to reproduce a pseudo-natural infection model, vaccinated pigs were allocated in the same pen with animals shedding virulent Salmonella Typhimurium. Animals were monitored weekly after vaccination and contact with infected piglets. Diarrhea and ataxia were recorded and Salmonella shedding was tested individually through bacterial culture. After four weeks of cohousing, piglets were euthanized, after which lymph nodes reactivity and gross lesions of the gut sections were scored at necropsy. Organs were submitted to microbiological and histological analyses. The data reported herein show that parenterally vaccinated animals do not shed the attenuated strain, and at the same time the absence of symptoms and decrease in virulent strain shedding in feces from day 6 after challenge demonstrated protection against infection induced by virulent Salmonella Typhimurium. In conclusion, our findings suggest that this is an alternative route of Salmonella Typhimurium ΔznuABC administration, without ignoring the advantages associated with oral vaccination. PMID:24907486

  15. Differences in the motility phenotype of multidrug-resistant Salmonella enterica serovar Typhimurium exposed to various antibiotics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is one of the most prevalent foodborne-associated bacteria in humans and livestock, and over 35 per cent of these isolates are resistant to three or more antibiotics. This is a concern as multidrug-resistant (MDR) Salmonella has been associat...

  16. Salmonella typhimurium phage type 141 infections in Sheffield during 1984 and 1985: association with hens' eggs.

    PubMed Central

    Chapman, P. A.; Rhodes, P.; Rylands, W.

    1988-01-01

    Food poisoning due to Salmonella typhimurium phage type 141 was unusual in the Sheffield area before 1984. The sudden increase in incidence of this phage type during 1984 and 1985, and its causative role in several small outbreaks in this period have been investigated. Epidemiological and laboratory investigations suggested that hens' eggs were the most likely source of S. typhimurium phage type 141. PMID:3042440

  17. Longevity of Salmonella typhimurium in Tilapia aurea and water from pools fertilized with swine waste.

    PubMed Central

    Baker, D A; Smitherman, R O; McCaskey, T A

    1983-01-01

    Salmonella typhimurium declined rapidly when inoculated into Tilapia aurea culture pools fertilized with fresh swine waste. Within the water column, a 95% decline of viable cells occurred during the first 6 h. Isolation of viable salmonellae was possible at 16 days post-inoculation, but not at 32 days. Similarly, salmonellae could be detected in the viscera and epithelium of T. aurea at 16 days, although not at 32 days. Salmonellae were not isolated from the fish flesh, nor was there evidence of septicemic infection. PMID:6347063

  18. Antibody Is Required for Protection against Virulent but Not Attenuated Salmonella enterica Serovar Typhimurium

    PubMed Central

    McSorley, Stephen J.; Jenkins, Marc K.

    2000-01-01

    Resolution of infection with attenuated Salmonella is an active process that requires CD4+ T cells. Here, we demonstrate that costimulation via the surface molecule CD28, but not antibody production by B cells, is required for clearance of attenuated aroA Salmonella enterica serovar typhimurium. In contrast, specific antibody is critical for vaccine-induced protection against virulent bacteria. Therefore, CD28+ CD4+ T cells are sufficient for clearance of avirulent Salmonella in naive hosts, whereas CD4+ T cells and specific antibodies are required for protection from virulent Salmonella in immune hosts. PMID:10816483

  19. Deletion of Invasion Protein B in Salmonella enterica Serovar Typhimurium Influences Bacterial Invasion and Virulence.

    PubMed

    Chen, Songbiao; Zhang, Chunjie; Liao, Chengshui; Li, Jing; Yu, Chuan; Cheng, Xiangchao; Yu, Zuhua; Zhang, Mingliang; Wang, Yang

    2015-12-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) has a wide host range and causes infections ranging from severe gastroenteritis to systemic infections in human, as well as causing typhoid-like disease in murine models of infection. S. Typhimurium translocates its effector proteins through the Salmonella pathogenicity island-I (SPI-I)-encoded T3SS-I needle complex. This study focuses on invasion protein B (SipB) of S. Typhimurium, which plays an active role in SPI-I invasion efficiency. To test our hypothesis, a sipB deletion mutant was constructed through double-crossover allelic using the suicide vector pRE112ΔsipB, and its biological characteristics were analyzed. The results showed that the SipB does not affect the growth of Salmonella, but the adherence, invasion, and virulence of the mutant were significantly decreased compared with wild-type S. Typhimurium (SL1344). This research indicates that SipB is an important virulence factor in the pathogenicity of S. Typhimurium. PMID:26341924

  20. Assessment of antibiotic resistance phenotype and integrons in Salmonella enterica serovar Typhimurium isolated from swine.

    PubMed

    Rayamajhi, Nabin; Kang, Sang Gyun; Kang, Mi Lan; Lee, Hee Soo; Park, Kyung Yoon; Yoo, Han Sang

    2008-10-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) isolated and identified from swine were subjected for the analysis of antibiotic resistance pattern and clinically important class 1 and 2 integrons. In addition, S. Typhimurium isolates exhibiting ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline and florfenicol (ACSSuTF) resistance pattern as described in most Salmonella enterica serotype Typhimurium definitive type 104 (DT104) were characterized by polymerase chain reaction. All the isolates were resistant to more than four antibiotics and showed the highest resistance to streptomycin (94.1%), followed by tetracycline (90.1%), ampicillin (64.7%), chloramphenicol (56.8%) and gentamicin (54.9%). MIC value for the ten isolates ranged between 0.125-2 mug/ml for ciprofloxacin. Among the beta-lactams used, only one of the isolate exhibited resistance to ceftiofur (MIC 8 microg/ml). Sixty eight percent of these multi drug resistance (MDR) S. Typhimurium isolates carried clinically important class 1 integron with 1kb (aadA) and/or 2kb (dhfrXII-orfF-aadA2) resistance gene cassettes. This study reports the increasing trend of multi drug resistance (MDR) S. Typhimurium with clinically important class 1 integron in pigs. In addition, emergence of the ACSSuTF-type resistance in S. Typhimurium PT other than DT104 may limit the use of resistance gene markers in its detection methods by PCR. PMID:18981675

  1. Requirement for cobalamin by Salmonella enterica serovars Typhimurium, Pullorum, Gallinarum and Enteritidis during infection in chickens

    PubMed Central

    Vaz, Jacqueline Boldrin; Penha Filho, Rafael Antonio Casarin; Junior, Angelo Berchieri; Lemos, Manoel Victor Franco

    2011-01-01

    Salmonella enterica serovar Typhimurium synthesizes cobalamin (vitamin B12) only during anaerobiosis. Two percent of the S. Typhimurium genome is devoted to the synthesis and uptake of vitamin B12 and to B12-dependent reactions. To understand the requirement for cobalamin synthesis better, we constructed mutants of Salmonella serovars Enteritidis and Pullorum that are double-defective in cobalamin biosynthesis (ΔcobSΔcbiA). We compared the virulence of these mutants to that of their respective wild type strains and found no impairment in their ability to cause disease in chickens. We then assessed B12 production in these mutants and their respective wild type strains, as well as in S. Typhimurium ΔcobSΔcbiA, Salmonella Gallinarum ΔcobSΔcbiA, and their respective wild type strains. None of the mutants was able to produce detectable B12. B12 was detectable in S. Enteritidis, S. Pullorum and S. Typhimurium wild type strains but not in S. Gallinarum. In conclusion, the production of vitamin B12in vitro differed across the tested Salmonella serotypes and the deletion of the cbiA and cobS genes resulted in different levels of alteration in the host parasite interaction according to Salmonella serotype tested. PMID:24031771

  2. Incomplete flagellar structures in nonflagellate mutants of Salmonella typhimurium.

    PubMed Central

    Suzuki, T; Iino, T; Horiguchi, T; Yamaguchi, S

    1978-01-01

    Incomplete flagellar structures were detected in osmotically shocked cells or membrane-associated fraction of many nonflagellate mutants of Salmonella typhimurium by electron microscopy. The predominant types of these structures in the mutants were cistron specific. The incomplete basal bodies were detected in flaFI, flaFIV, flaFVIII, and flaFIX mutants, the structure homologous to a basal body in flaFV mutants, the polyhook-basal body complex in flaR mutants, and the hook-basal body complex in flaL and flaU mutants. No structures homologous to flagellar bases or their parts were detected in the early-fla group nonflagellate mutants of flaAI, flaAII, flaAIII, flaB, flaC, flaD, flaE, flaFII, flaFIII, flaFVI, flaFVII, flaFX, flaK, and flaM. From these observations, a process of flagellar morphogenesis was postulated. The functions of the early-fla group are essential to the formation of S ring-M ring-rod complexes bound to the membrane. The completion of basal bodies requires succeeding functions of flaFI, flaFIV, flaFVIII, and flaFIX. Next, the formation of hooks attached to basal bodies proceeds by the function of flaFV and by flaR, which controls the hook length. Flagellar filaments appear at the tips of hooks because of the functions of flaL, flaU, and flagellin genes. Images PMID:342514

  3. Cyclic AMP phosphodiesterase in Salmonella typhimurium: characteristics and physiological function.

    PubMed

    Botsford, J L

    1984-11-01

    The physiological function of cyclic AMP (cAMP) phosphodiesterase in Salmonella typhimurium was investigated with strains which were isogenic except for the cpd locus. In crude broken-cell extracts the properties of the enzyme were found to be similar to those reported for Escherichia coli. The specific activity in the mutant was less than 1% that in the wild type. Rates of cAMP production in the mutant were as much as twice those observed in the wild type. The amount of cAMP accumulated when cells grew overnight with limiting glucose was 4.5-fold greater in the mutant than in the wild type. The intracellular concentration of cAMP in the two strains was measured directly, using four different techniques to wash the cells to remove extracellular cAMP. The cAMP level in the cpd strain was only 25% greater than in the wild type. The functional concentration of the cAMP receptor protein-cAMP complex was estimated indirectly from the specific activity of beta-galactosidase in the two strains after introducing F'lac. When cells were grown with carbon sources permitting synthesis of different levels of cAMP, the specific activity of the enzyme was at most 25% greater in the cpd strain. The cpd strain was more sensitive to the effects of exogenous cAMP. Exogenous cAMP relieved both permanent and transient catabolite repression of the lac operon at lower concentrations in the cpd strain than in the wild type. When cells grew with glucose, glycerol, or ribose, exogenous cAMP inhibited growth of the mutant strain more than the wild type. PMID:6094495

  4. Frequency of generalized transducing phages in natural isolates of the Salmonella typhimurium complex.

    PubMed Central

    Schicklmaier, P; Schmieger, H

    1995-01-01

    From 85 natural isolates of the Salmonella typhimurium complex, including the Salmonella reference collection A (P. Beltran, S. A. Plock, N. H. Smith, T. S. Whittam, D. C. Old, and R. K. Selander, J. Gen. Microbiol. 137:601-606, 1991), 65 strains (76.5%) released 71 different temperate phages. Forty-three (93.5%) of 46 tested phages were able to transduce the chromosomal markers his+ and trp+ and the cloning vector pBR325. PMID:7747978

  5. Isolation and mapping of a uracil-sensitive mutant of Salmonella typhimurium.

    PubMed

    Bussey, L B; Ingraham, J L

    1982-01-01

    A uracil-sensitive mutant of Salmonella typhimurium was isolated by diethyl sulfate mutagenesis and penicillin counterselection. This mutation identifies a new Salmonella gene that is well separated from the structural genes for arginine and pyrimidine biosynthesis. The use-1 mutation was located between the ilv gene cluster (isoleucine-valine operon) and hisR (structural gene for histidine tRNA) at 83 map units. PMID:7048028

  6. Virulent Salmonella typhimurium-induced lymphocyte depletion and immunosuppression in chickens.

    PubMed Central

    Hassan, J O; Curtiss, R

    1994-01-01

    The effect of experimental Salmonella infection on chicken lymphoid organs, immune responses, and fecal shedding of salmonellae were assessed following oral inoculation of 1-day-old chicks or intra-air-sac infection of 4-week-old chickens with virulent S. typhimurium wild-type chi 3761 or avirulent S. typhimurium delta cya delta crp vaccine strain chi 3985. Some 4-week-old chickens infected intra-air-sac with chi 3761 or chi 3985 were challenged with Bordetella avium to determine the effect of Salmonella infection on secondary infection by B. avium. S. typhimurium chi 3761 caused lymphocyte depletion, atrophy of lymphoid organs, and immunosuppression 2 days after infection in 1-day-old chicks and 4-week-old chickens. The observed lymphocyte depletion or atrophy of lymphoid organs was transient and dose dependent. Lymphocyte depletion and immunosuppression were associated with prolonged fecal shedding of S. typhimurium chi 3761. No lymphocyte depletion, immunosuppression, or prolonged Salmonella shedding was observed in groups of chickens infected orally or intra-air-sac with chi 3985. Infection of chickens with salmonellae before challenge with B. avium did not suppress the specific antibody response to B. avium. However, B. avium isolation was higher in visceral organs of chickens infected with chi 3761 and challenged with B. avium than in chickens infected with B. avium only. Infection of chickens with chi 3985 reduced B. avium colonization. We report a new factor in Salmonella pathogenesis and reveal a phenomenon which may play a critical role in the development of Salmonella carrier status in chickens. We also showed that 10(8) CFU of chi 3985, which is our established oral vaccination dose for chickens, did not cause immunosuppression or enhance the development of Salmonella carrier status in chickens. Images PMID:8168969

  7. 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. PMID:27260804

  8. 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

  9. Global Transcriptome and Mutagenic Analyses of the Acid Tolerance Response of Salmonella enterica Serovar Typhimurium

    PubMed Central

    Ryan, Daniel; Pati, Niladri Bhusan; Ojha, Urmesh K.; Padhi, Chandrashekhar; Ray, Shilpa; Jaiswal, Sangeeta; Singh, Gajinder P.; Mannala, Gopala K.; Schultze, Tilman; Chakraborty, Trinad

    2015-01-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is one of the leading causative agents of food-borne bacterial gastroenteritis. Swift invasion through the intestinal tract and successful establishment in systemic organs are associated with the adaptability of S. Typhimurium to different stress environments. Low-pH stress serves as one of the first lines of defense in mammalian hosts, which S. Typhimurium must efficiently overcome to establish an infection. Therefore, a better understanding of the molecular mechanisms underlying the adaptability of S. Typhimurium to acid stress is highly relevant. In this study, we have performed a transcriptome analysis of S. Typhimurium under the acid tolerance response (ATR) and found a large number of genes (∼47%) to be differentially expressed (more than 1.5-fold or less than −1.5-fold; P < 0.01). Functional annotation revealed differentially expressed genes to be associated with regulation, metabolism, transport and binding, pathogenesis, and motility. Additionally, our knockout analysis of a subset of differentially regulated genes facilitated the identification of proteins that contribute to S. Typhimurium ATR and virulence. Mutants lacking genes encoding the K+ binding and transport protein KdpA, hypothetical protein YciG, the flagellar hook cap protein FlgD, and the nitrate reductase subunit NarZ were significantly deficient in their ATRs and displayed varied in vitro virulence characteristics. This study offers greater insight into the transcriptome changes of S. Typhimurium under the ATR and provides a framework for further research on the subject. PMID:26386064

  10. Cloning, sequencing, expression and characterization of DNA photolyase from Salmonella typhimurium.

    PubMed Central

    Li, Y F; Sancar, A

    1991-01-01

    We have cloned the phr gene that encodes DNA photolyase from Salmonella typhimurium by in vivo complementation of Escherichia coli phr gene defect. The S.typhimurium phr gene is 1419 base pairs long and the deduced amino acid sequence has 80% identity with that of E. coli photolyase. We expressed the S.typhimurium phr gene in E.coli by ligating the E.coli trc promoter 5' to the gene, and purified the enzyme to near homogeneity. The apparent molecular weight of S.typhimurium photolyase is 54,000 dalton as determined by SDS-polyacrylamide gel electrophoresis, which is consistent with the calculated molecular weight of 53,932 dalton from the deduced phr gene product. S.typhimurium photolyase is purple-blue in color with near UV-visible absorption peaks at 384, 480, 580, and 625 nm and a fluorescence peak at 470 nm. From the characteristic absorption and fluorescence spectra and reconstitution experiments, S.typhimurium photolyase appears to contain flavin and methenyltetrahydrofolate as chromophore-cofactors as do the E.coli and yeast photolyases. Thus, S.typhimurium protein is the third folate class photolyase to be cloned and characterized to date. The binding constant of S.typhimurium photolyase to thymine dimer in DNA is kD = 1.6 x 10(-9) M, and the quantum yield of photorepair at 384 nm is 0.5. Images PMID:1840665

  11. 2D proteome analysis initiates new Insights on the Salmonella Typhimurium LuxS protein

    PubMed Central

    2009-01-01

    Background Quorum sensing is a term describing a bacterial communication system mediated by the production and recognition of small signaling molecules. The LuxS enzyme, catalyzing the synthesis of AI-2, is conserved in a wide diversity of bacteria. AI-2 has therefore been suggested as an interspecies quorum sensing signal. To investigate the role of endogenous AI-2 in protein expression of the Gram-negative pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), we performed a 2D-DIGE proteomics experiment comparing total protein extract of wildtype S. Typhimurium with that of a luxS mutant, unable to produce AI-2. Results Differential proteome analysis of wildtype S. Typhimurium versus a luxS mutant revealed relatively few changes beyond the known effect on phase 2 flagellin. However, two highly differentially expressed protein spots with similar molecular weight but differing isoelectric point, were identified as LuxS whereas the S. Typhimurium genome contains only one luxS gene. This observation was further explored and we show that the S. Typhimurium LuxS protein can undergo posttranslational modification at a catalytic cysteine residue. Additionally, by constructing LuxS-βla and LuxS-PhoA fusion proteins, we demonstrate that S. Typhimurium LuxS can substitute the cognate signal peptide sequences of β-lactamase and alkaline phosphatase for translocation across the cytoplasmic membrane in S. Typhimurium. This was further confirmed by fractionation of S. Typhimurium protein extracts, followed by Western blot analysis. Conclusion 2D-DIGE analysis of a luxS mutant vs. wildtype Salmonella Typhimurium did not reveal new insights into the role of AI-2/LuxS in Salmonella as only a small amount of proteins were differentially expressed. However, subsequent in depth analysis of the LuxS protein itself revealed two interesting features: posttranslational modification and potential translocation across the cytoplasmic membrane. As the S. Typhimurium Lux

  12. 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

  13. Analysis of the Salmonella typhimurium Proteome through Environmental Response toward Infectious Conditions

    SciTech Connect

    Adkins, Joshua N.; Mottaz, Heather M.; Norbeck, Angela D.; Gustin, Jean K.; Rue, Joanne; Clauss, Therese RW; Purvine, Samuel O.; Rodland, Karin D.; Heffron, Fred; Smith, Richard D.

    2006-08-01

    Salmonella enterica serovar Typhimurium (aka, S. typhimurium) is a facultative intracellular pathogen that causes ~40,000 reported cases of acute gastroenteritis and diarrhea a year in the United States. To develop a deeper understanding of the infectious state of S. typhimurium, liquid chromatography-mass spectrometry-based “bottom-up” proteomics was used to globally analyze the proteins present under specific growth conditions. Salmonella typhimurium LT2 strain cells were grown in contrasting culture conditions that mimicked both natural free-living conditions and an infectious state, i.e., logarithm phase, stationary phase and Mg-depleted medium growth. Initial comparisons of the LT2 strain protein abundances among cell culture conditions indicate that the majority of proteins do not change significantly. Not unexpectedly, cells grown in Mg-depleted medium conditions had a higher abundance of Mg2+ transport proteins than found in other growth conditions. A second more virulent Salmonella typhimurium strain (14028) was also studied with these growth conditions and used to directly compare to the LT2 strain. The strain comparison offers a unique opportunity to compare and contrast observations in these closely related bacteria. One particular protein family, propanediol utilization proteins, was drastically more abundant in the 14028 strain than in the LT2 strain, and may be a contributor to increased pathogenicity in the 14028 strain.

  14. REDUCTION OF SALMONELLA TYPHIMURIUM IN EXPERIMENTALLY CHALLENGED BROILERS BY NITRATE ADAPTATION AND CHLORATE SUPPLEMENTATION IN DRINKING WATER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteria in the genus Salmonella are recognized as major foodborne pathogens. Consequently, the elimination of Salmonella before harvest is desired. In the present study, the effect of two feed supplements on Salmonella Typhimurium (ST) presence in the ceca of market-age broilers was determined. ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  16. Influence of light exposure on horizontal transmission of Salmonella typhimurium in weaned pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of the following experiment was to examine the effect of light exposure on horizontal transmission of Salmonella typhimurium in weaned pigs. Twenty crossbred pigs (average BW = 15 kg) were housed in isolation rooms (10 pigs/room) and randomly assigned to one of two lighting regimes: ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. PORCINE DIFFERENTIAL GENE EXPRESSION IN RESPONSE TO SALMONELLA ENTERICA SEROVARS CHOLERAESUIS AND TYPHIMURIUM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using suppression subtractive hybridization (SSH) and real-time PCR, an investigation of the porcine response to infection with Salmonella enterica serovars Choleraesuis (narrow host range) and Typhimurium (broad host range) revealed different transcriptional profiles. Ten genes identified by SSH a...

  19. GLOBAL TRANSCRIPTIONAL RESPONSE OF PORCINE MESENTERIC LYMPH NODES TO SALMONELLA ENTERICA SEROVAR TYPHIMURIUM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonellosis is prevalent worldwide and is both a food safety and animal production problem. To understand the host transcriptional response to Salmonella enterica serovar Typhimurium, the Affymetrix GeneChip® porcine genome array was used to identify differentially expressed (DE) genes in mesente...

  20. MUTAGENICITY OF 7H-DIBENZO(C,G)CARBAZOLE AND METABOLITES IN SALMONELLA TYPHIMURIUM

    EPA Science Inventory

    7H-Dibenzo(c,g)carbazole (DBC) is a potent carcinogen of environmental import. Reverse-mutation plate-incorporation assays for mutagenicity were undertaken in Salmonella typhimurium strains TA98 and TA100. esults were negative when no exogenous activation system was used, as well...

  1. Autoinducer AI-2 is involved in regulating a variety of cellular processes in Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    LuxS/AI-2 mediated cell signaling is a known strategy that modulates a variety of bacterial processes in prokaryotes. Salmonella Typhimurium is known to possess LuxS/AI-2 mediated cell signaling. Until now, the Lsr- ABC transporter system (LuxS- regulated) is the only known process controlled by t...

  2. Inhibition of Salmonella Typhimurium by Cultures of Cecal Bacteria during Aerobic Incubation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two trials were conducted to examine the ability of cecal bacterial cultures from broilers to inhibit growth of Salmonella Typhimurium during aerobic incubation. Cecal broth media was inoculated with 10 µl of cecal contents from 6 week old broilers taken from 2 separate flocks. Cultures were incubat...

  3. In vitro inhibition of growth of Escherichia coli, Salmonella Typhimurium, and Clostridia perfringens using Probiotics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella Typhimurium, Escherichia coli and Clostridium perfringens are pathogenic organisms found in horses [1] and they cause disease in animals or humans [2]. Due to concern over pathogens such as these, there is increasing interest in antimicrobial alternatives to prevent or reduce the prevalen...

  4. Osmoregulated periplasmic glucans of Salmonella enterica serovar Typhimurium are required for optimal virulence in mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We purified osmoregulated periplasmic glucans (OPGs) from Salmonella enterica serovar Typhimurium and found them to be composed of 100% glucose with 2-linked glucose as the most abundant residue with terminal glucose, 2,3-linked and 2,6-linked glucose also present in high quantities. The two structu...

  5. A WATERBORNE SALMONELLA TYPHIMURIUM OUTBREAK IN GIDEON, MISSOURI: RESULTS FROM A FIELD INVESTIGATION

    EPA Science Inventory

    A waterborne disease outbreak associated with Salmonella typhimurium was identified in Gideon, Missouri (population 1104), a town in southeastern Missouri (USA) in December, 1993. It was estimated by the US Centers for Disease Control and Prevention (CDC) that approximately 44% o...

  6. Invasive Salmonella enterica serotype typhimurium infections, Democratic Republic of the Congo, 2007-2011.

    PubMed

    Ley, Benedikt; Le Hello, Simon; Lunguya, Octavie; Lejon, Veerle; Muyembe, Jean-Jacques; Weill, François-Xavier; Jacobs, Jan

    2014-04-01

    Infection with Salmonella enterica serotype Typhimurium sequence type (ST) 313 is associated with high rates of drug resistance, bloodstream infections, and death. To determine whether ST313 is dominant in the Democratic Republic of the Congo, we studied 180 isolates collected during 2007-2011; 96% belonged to CRISPOL type CT28, which is associated with ST313. PMID:24655438

  7. Inhibition of Salmonella Typhimurium by Anaerobic Cecal Bacteria in Media Supplemented with Lactate and Succinate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of anaerobic cecal microflora of broilers to inhibit growth of Salmonella Typhimurium in media supplemented with lactate and succinate was examined. Cecal cultures were prepared by collecting ceca of processed broilers from a commercial processing facility, inoculating broth media with 1...

  8. Rice hull smoke extract inactivates Salmonella Typhimurium in laboratory media and protects infected mice against mortality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A recently discovered and characterized rice hull liquid smoke extract was tested for bactericidal activity against Salmonella Typhimurium using the disc-agar method. The Minimum Inhibitory Concentration (MIC) value of rice hull smoke extract was found to be 0.822% (v/v). The in vivo antibacterial a...

  9. Effectiveness of radiation processing for elimination of Salmonella Typhimurium from minimally processed pineapple (Ananas comosus Merr.).

    PubMed

    Shashidhar, Ravindranath; Dhokane, Varsha S; Hajare, Sachin N; Sharma, Arun; Bandekar, Jayant R

    2007-04-01

    The microbiological quality of market samples of minimally processed (MP) pineapple was examined. The effectiveness of radiation treatment in eliminating Salmonella Typhimurium from laboratory inoculated ready-to-eat pineapple slices was also studied. Microbiological quality of minimally processed pineapple samples from Mumbai market was poor; 8.8% of the samples were positive for Salmonella. D(10) (the radiation dose required to reduce bacterial population by 90%) value for S. Typhimurium inoculated in pineapple was 0.242 kGy. Inoculated pack studies in minimally processed pineapple showed that the treatment with a 2-kGy dose of gamma radiation could eliminate 5 log CFU/g of S. Typhimurium. The pathogen was not detected from radiation-processed samples up to 12 d during storage at 4 and 10 degrees C. The processing of market samples with 1 and 2 kGy was effective in improving the microbiological quality of these products. PMID:17995808

  10. An infection-relevant transcriptomic compendium for Salmonella enterica Serovar Typhimurium.

    PubMed

    Kröger, Carsten; Colgan, Aoife; Srikumar, Shabarinath; Händler, Kristian; Sivasankaran, Sathesh K; Hammarlöf, Disa L; Canals, Rocío; Grissom, Joe E; Conway, Tyrrell; Hokamp, Karsten; Hinton, Jay C D

    2013-12-11

    Bacterial transcriptional networks consist of hundreds of transcription factors and thousands of promoters. However, the true complexity of transcription in a bacterial pathogen and the effect of the environments encountered during infection remain to be established. We present a simplified approach for global promoter identification in bacteria using RNA-seq-based transcriptomic analyses of 22 distinct infection-relevant environmental conditions. Individual RNA samples were combined to identify most of the 3,838 Salmonella enterica serovar Typhimurium promoters in just two RNA-seq runs. Individual in vitro conditions stimulated characteristic transcriptional signatures, and the suite of 22 conditions induced transcription of 86% of all S. Typhimurium genes. We highlight the environmental conditions that induce the Salmonella pathogenicity islands and present a small RNA expression landscape of 280 sRNAs. This publicly available compendium of environmentally controlled expression of every transcriptional feature of S. Typhimurium constitutes a useful resource for the bacterial research community. PMID:24331466

  11. Evaluating Chemical Mitigation of Salmonella Typhimurium ATCC 14028 in Animal Feed Ingredients.

    PubMed

    Cochrane, Roger A; Huss, Anne R; Aldrich, Gregory C; Stark, Charles R; Jones, Cassandra K

    2016-04-01

    Salmonella Typhimurium is a potential feed safety hazard in animal feed ingredients. Thermal mitigation of Salmonella spp. during rendering is effective but does not eliminate the potential for cross-contamination. Therefore, the objective of this experiment was to evaluate the effectiveness of chemicals to mitigate postrendering Salmonella Typhimurium ATCC 14028 contamination in rendered proteins over time. Treatments were arranged in a 6 × 4 factorial with six chemical treatments and four rendered protein meals. The chemical treatments included (i) control without chemical treatment, (ii) 0.3% commercial formaldehyde product, (iii) 2% essential oil blend, (iv) 2% medium chain fatty acid blend, (v) 3% organic acid blend, and (vi) 1% sodium bisulfate. The four rendered protein meals included (i) feather meal, (ii) blood meal, (iii) meat and bone meal, and (iv) poultry by-product meal. After matrices were chemically treated, they were inoculated with Salmonella Typhimurium ATCC 14028, stored at room temperature, and enumerated via plate counts on days 0, 1, 3, 7, 14, 21, and 42 postinoculation. The Salmonella concentration in ingredients treated with medium chain fatty acid and commercial formaldehyde were similar to one another (P = 0.23) but were 2 log lower than the control (P < 0.05). Ingredients treated with organic acids and essential oils also had lower Salmonella concentrations than the control (P < 0.05). Time also played a significant role in Salmonella mitigation, because all days except days 14 and 21 (P = 0.92) differed from one another. Rendered protein matrix also affected Salmonella stability, because concentrations in meat and bone meal and blood meal were similar to one another (P = 0.36) but were greater than levels in feather meal and poultry by-product meal (P < 0.05). In summary, chemical treatment and time both mitigated Salmonella Typhimurium ATCC 14028, but their effectiveness was matrix dependent. Time and chemical treatment with medium

  12. Nitrosative stress causes amino acid auxotrophy in hmp mutant Salmonella Typhimurium.

    PubMed

    Park, Yoon Mee; Park, Hee Jeong; Joung, Young Hee; Bang, Iel Soo

    2011-10-01

    Cytotoxic nitic oxide (NO) damages various bacterial macromolecules, resulting in abnormal metabolism by mechanisms largely unknown. We show that NO can cause amino acid auxotrophy in Salmonella Typhimurium lacking major NO-metabolizing enzyme, flavohemoglobin Hmp. In NO-producing cultures, supplementation with amino acid pool restores growth of Hmp-deficient Salmonella to normal growth phases, whereas excluding Cys or BCAA Leu, Ile, or Val from amino acid pool reduces growth recovery. Data suggest that, without detoxification, NO might inactivate key enzymes in the biosynthesis pathway of amino acids essential for Salmonella replication in amino acid-limiting host environments. PMID:21752086

  13. Design of Glycoconjugate Vaccines against Invasive African Salmonella enterica Serovar Typhimurium

    PubMed Central

    Micoli, F.; Lanzilao, L.; Gavini, M.; Alfini, R.; Brandt, C.; Clare, S.; Mastroeni, P.; Saul, A.; MacLennan, C. A.

    2014-01-01

    Nontyphoidal salmonellae, particularly Salmonella enterica serovar Typhimurium, are a major cause of invasive disease in Africa, affecting mainly young children and HIV-infected individuals. Glycoconjugate vaccines provide a safe and reliable strategy against invasive polysaccharide-encapsulated pathogens, and lipopolysaccharide (LPS) is a target of protective immune responses. With the aim of designing an effective vaccine against S. Typhimurium, we have synthesized different glycoconjugates, by linking O-antigen and core sugars (OAg) of LPS to the nontoxic mutant of diphtheria toxin (CRM197). The OAg-CRM197 conjugates varied in (i) OAg source, with three S. Typhimurium strains used for OAg extraction, producing OAg with differences in structural specificities, (ii) OAg chain length, and (iii) OAg/CRM197 ratio. All glycoconjugates were compared for immunogenicity and ability to induce serum bactericidal activity in mice. In vivo enhancement of bacterial clearance was assessed for a selected S. Typhimurium glycoconjugate by challenge with live Salmonella. We found that the largest anti-OAg antibody responses were elicited by (i) vaccines synthesized from OAg with the highest glucosylation levels, (ii) OAg composed of mixed- or medium-molecular-weight populations, and (iii) a lower OAg/CRM197 ratio. In addition, we found that bactericidal activity can be influenced by S. Typhimurium OAg strain, most likely as a result of differences in OAg O-acetylation and glucosylation. Finally, we confirmed that mice immunized with the selected OAg-conjugate were protected against S. Typhimurium colonization of the spleen and liver. In conclusion, our findings indicate that differences in the design of OAg-based glycoconjugate vaccines against invasive African S. Typhimurium can have profound effects on immunogenicity and therefore optimal vaccine design requires careful consideration. PMID:25547792

  14. Mouse hepatitis virus strain UAB infection enhances resistance to Salmonella typhimurium in mice by inducing suppression of bacterial growth.

    PubMed Central

    Fallon, M T; Benjamin, W H; Schoeb, T R; Briles, D E

    1991-01-01

    We have previously shown that intranasal infection of mice with mouse hepatitis virus (MHV) strain UAB (MHV-UAB) increases their resistance to Salmonella typhimurium injected intravenously 6 days later. To study how salmonella resistance was induced, BALB/cAnNCr mice were infected with salmonella strains carrying specific genetic alterations. One set of studies compared the effect of MHV infection on subsequent salmonella infections with AroA- (avirulent) and Aro+ (virulent) salmonellae. Unlike its effect on Aro+ salmonellae, MHV failed to reduce the number of AroA- salmonellae recovered from mice. Because AroA- S. typhimurium shows almost no growth in vivo, this failure indicated that the effect of MHV on salmonella resistance required growth of the infecting salmonellae. In other studies, the effect of MHV infection on both growth and killing were monitored simultaneously in mice with growing salmonellae carrying a single copy of the temperature-sensitive pHSG422 plasmid, which is unable to replicate in vivo. MHV infection reduced salmonella growth but caused no increase in salmonella killing. MHV infection of mice given wild-type salmonellae also resulted in no increase in salmonella killing 4 h after salmonella challenge. These studies demonstrate that MHV-UAB infection increases host resistance to salmonellae by enhancing suppression of bacterial growth instead of by increasing the amount of salmonella killing. PMID:1847697

  15. 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

  16. Neutrophils Are a Source of Gamma Interferon during Acute Salmonella enterica Serovar Typhimurium Colitis

    PubMed Central

    Spees, Alanna M.; Kingsbury, Dawn D.; Wangdi, Tamding; Xavier, Mariana N.; Tsolis, Renée M.

    2014-01-01

    Gamma interferon (IFN-γ) is an important driver of intestinal inflammation during colitis caused by Salmonella enterica serovar Typhimurium. Here we used the mouse colitis model to investigate the cellular sources of IFN-γ in the cecal mucosa during the acute phase of an S. Typhimurium infection. While IFN-γ staining was detected in T cells, NK cells, and inflammatory monocytes at 2 days after infection, the majority of IFN-γ-positive cells in the cecal mucosa were neutrophils. Furthermore, neutrophil depletion blunted mucosal Ifng expression and reduced the severity of intestinal lesions during S. Typhimurium infection. We conclude that neutrophils are a prominent cellular source of IFN-γ during the innate phase of S. Typhimurium-induced colitis. PMID:24421037

  17. 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

  18. Protection of mice against Salmonella typhimurium with an O-specific polysaccharide-protein conjugate vaccine.

    PubMed Central

    Watson, D C; Robbins, J B; Szu, S C

    1992-01-01

    Serious infections with salmonellae remain a threat in many human populations. Despite extensive study of salmonella infections in animals and clinical experience with killed cellular vaccines, there are no vaccines against serotypes other than Salmonella typhi licensed for human use. Serum antibodies to the O-specific polysaccharide (O-SP) of salmonellae protect mice against invasive infection. In order to render it immunogenic, we have conjugated the O-SP of Salmonella typhimurium to carrier proteins by various schemes. O-SP conjugated to tetanus toxoid (O-SP-TT) elicited antibodies in outbred mice after three subcutaneous injections without adjuvant. The O-SP alone elicited no detectable antibody. The antibody response to O-SP-TT was boosted by successive doses and consisted of immunoglobulin G (IgG) and IgM. Most mice only produced antibodies specific for the abequose (O:4 factor) region of the O-SP. Occasional animals also produced antibodies to the core oligosaccharide. Immunized mice were protected against intraperitoneal challenge with S. typhimurium, demonstrating a 160-fold increase in the 50% lethal dose. Passive immunization with conjugate-induced IgM or IgG also protected against challenge. These results indicate that an O-SP-TT conjugate, when given by a route and formulation acceptable for human use, protects mice against challenge with S. typhimurium. Images PMID:1383154

  19. Organically managed soils reduce internal colonization of tomato plants by Salmonella enterica serovar Typhimurium.

    PubMed

    Gu, Ganyu; Cevallos-Cevallos, Juan M; Vallad, Gary E; van Bruggen, Ariena H C

    2013-04-01

    A two-phase experiment was conducted twice to investigate the effects of soil management on movement of Salmonella enterica Typhimurium in tomato plants. In the first phase, individual leaflets of 84 tomato plants grown in conventional or organic soils were dip inoculated two to four times before fruiting with either of two Salmonella Typhimurium strains (10(9) CFU/ml; 0.025% [vol/vol] Silwet L-77). Inoculated and adjacent leaflets were tested for Salmonella spp. densities for 30 days after each inoculation. Endophytic bacterial communities were characterized by polymerase chain reaction denaturing gradient gel electrophoresis before and after inoculation. Fruit and seed were examined for Salmonella spp. incidence. In phase 2, extracted seed were planted in conventional soil, and contamination of leaves and fruit of the second generation was checked. More Salmonella spp. survived in inoculated leaves on plants grown in conventional than in organic soil. The soil management effect on Salmonella spp. survival was confirmed for tomato plants grown in two additional pairs of soils. Endophytic bacterial diversities of tomato plants grown in conventional soils were significantly lower than those in organic soils. All contaminated fruit (1%) were from tomato plants grown in conventional soil. Approximately 5% of the seed from infested fruit were internally contaminated. No Salmonella sp. was detected in plants grown from contaminated seed. PMID:23506364

  20. A novel FRET-based optical fiber biosensor for rapid detection of Salmonella typhimurium.

    PubMed

    Ko, Sungho; Grant, Sheila A

    2006-01-15

    A biosensor that is portable and permits on-site analysis of samples would significantly reduce the large economical burden of food products recalls. A fiber optic portable biosensor utilizing the principle of fluorescence resonance energy transfer (FRET) was developed for fast detection of Salmonella typhimurium (S. typhimurium) in ground pork samples. Labeled antibody-protein G complexes were formed via the incubation of anti-Salmonella antibodies labeled with FRET donor fluorophores (Alexa Fluor 546) and protein G (PG) labeled with FRET acceptor fluorophores (Alexa Fluor 594). Utilizing silanization, the labeled antibodies-PG complexes were then immobilized on decladded, tapered silica fiber cores to form the evanescent wave-sensing region. The biosensors were tested in two different solutions: (1) PBS doped with S. typhimurium and (2) homogenized pork sample with S. typhimurium. The fiber probes tested in a S. typhimurium doped phosphate buffered solution demonstrated the feasibility of the biosensor for detecting S. typhimurium as well as determined the optimal packing density of the labeled antibody-PG complexes on the surface of fibers. The results showed that a packing density of 0.033 mg/ml produced the lowest limit of detection of 10(3)cells/ml with 8.2% change in fluorescence. The fiber probes placed in homogenized pork samples inoculated with S. typhimurium showed a limit of detection of 10(5)CFU/g with a 6.67% in fluorescence within a 5-min response time. These results showed that the FRET-based fiber optic biosensor can become a useful analytical tool for detection of S. typhimurium in real food samples. PMID:16040238

  1. Yersinia enterocolitica inhibits Salmonella enterica serovar Typhimurium and Listeria monocytogenes cellular uptake.

    PubMed

    Habyarimana, Fabien; Swearingen, Matthew C; Young, Glenn M; Seveau, Stephanie; Ahmer, Brian M M

    2014-01-01

    Yersinia enterocolitica biovar 1B employs two type three secretion systems (T3SS), Ysa and Ysc, which inject effector proteins into macrophages to prevent phagocytosis. Conversely, Salmonella enterica serovar Typhimurium uses a T3SS encoded by Salmonella pathogenicity island 1 (SPI1) to actively invade cells that are normally nonphagocytic and a second T3SS encoded by SPI2 to survive within macrophages. Given the distinctly different outcomes that occur with regard to host cell uptake of S. Typhimurium and Y. enterocolitica, we investigated how each pathogen influences the internalization outcome of the other. Y. enterocolitica reduces S. Typhimurium invasion of HeLa and Caco-2 cells to a level similar to that observed using an S. Typhimurium SPI1 mutant alone. However, Y. enterocolitica had no effect on S. Typhimurium uptake by J774.1 or RAW264.7 macrophage-like cells. Y. enterocolitica was also able to inhibit the invasion of epithelial and macrophage-like cells by Listeria monocytogenes. Y. enterocolitica mutants lacking either the Ysa or Ysc T3SS were partially defective, while double mutants were completely defective, in blocking S. Typhimurium uptake by epithelial cells. S. Typhimurium encodes a LuxR homolog, SdiA, which detects N-acylhomoserine lactones (AHLs) produced by Y. enterocolitica and upregulates the expression of an invasin (Rck) and a putative T3SS effector (SrgE). Two different methods of constitutively activating the S. Typhimurium SdiA regulon failed to reverse the uptake blockade imposed by Y. enterocolitica. PMID:24126528

  2. Yersinia enterocolitica Inhibits Salmonella enterica Serovar Typhimurium and Listeria monocytogenes Cellular Uptake

    PubMed Central

    Habyarimana, Fabien; Swearingen, Matthew C.; Young, Glenn M.; Seveau, Stephanie

    2014-01-01

    Yersinia enterocolitica biovar 1B employs two type three secretion systems (T3SS), Ysa and Ysc, which inject effector proteins into macrophages to prevent phagocytosis. Conversely, Salmonella enterica serovar Typhimurium uses a T3SS encoded by Salmonella pathogenicity island 1 (SPI1) to actively invade cells that are normally nonphagocytic and a second T3SS encoded by SPI2 to survive within macrophages. Given the distinctly different outcomes that occur with regard to host cell uptake of S. Typhimurium and Y. enterocolitica, we investigated how each pathogen influences the internalization outcome of the other. Y. enterocolitica reduces S. Typhimurium invasion of HeLa and Caco-2 cells to a level similar to that observed using an S. Typhimurium SPI1 mutant alone. However, Y. enterocolitica had no effect on S. Typhimurium uptake by J774.1 or RAW264.7 macrophage-like cells. Y. enterocolitica was also able to inhibit the invasion of epithelial and macrophage-like cells by Listeria monocytogenes. Y. enterocolitica mutants lacking either the Ysa or Ysc T3SS were partially defective, while double mutants were completely defective, in blocking S. Typhimurium uptake by epithelial cells. S. Typhimurium encodes a LuxR homolog, SdiA, which detects N-acylhomoserine lactones (AHLs) produced by Y. enterocolitica and upregulates the expression of an invasin (Rck) and a putative T3SS effector (SrgE). Two different methods of constitutively activating the S. Typhimurium SdiA regulon failed to reverse the uptake blockade imposed by Y. enterocolitica. PMID:24126528

  3. Isolation of Salmonella typhimurium from dead blue and gold macaws (Ara ararauna).

    PubMed

    Vigo, Germán B; Origlia, Javier; Gornatti, Daniel; Piscopo, Miguel; Salve, Angela; Caffer, María I; Pichel, Mariana; Binsztein, Norma; Leotta, Gerardo A

    2009-03-01

    Two blue and gold macaw (Ara ararauna) chicks died of fatal salmonellosis in Buenos Aires Province, Argentina. The birds were histopathologically and microbiologically examined. Salmonella enterica subspecies enterica serovar Typhimurium was isolated from the liver, spleen, heart, lung, kidney, and intestine of both birds. All strains were susceptible to ampicillin, cephalothin, cefotaxime, enrofloxacin, nalidixic acid, gentamicin, streptomycin, chloramphenicol, fosfomycin, tetracycline, nitrofurantoin, and trimethoprim-sulfamethoxazole. The XbaI-PFGE profile of the Salmonella Typhimurium isolated from the two animals, which shared the same cage, was identical and showed a unique pattern compared with 301 isolates included in the PulseNet national database of Salmonella pulsed-field gel electrophoresis patterns. This is the first report that describes fatal cases of salmonellosis from blue and gold macaws. PMID:19432017

  4. A conditionally lethal mutant of Salmonella Typhimurium induces a protective response in mice.

    PubMed

    Hidalgo, Alejandro A; Villagra, Nicolás A; Jerez, Sebastián A; Fuentes, Juan A; Mora, Guido C

    2016-02-01

    Here we present the design of a conditionally lethal mutant of Salmonella enterica serovar Typhimurium (S. Typhimurium) which growth depends on tetracycline (Tet). Four mutants of S. Typhimurium, with Tet-conditional growth, were created by inserting the tetRA cassette. Three of the mutants presented a conditional-lethal phenotype in vitro. One mutant in the yabB gene remained conditional inside cells and did not persisted after 24 h in cell cultures. The capacity of S. Typhimurium yabB::tetRA to invade deep organs was investigated in intraperitoneally (IP) infected mice fed with or without chlortetracycline (CTet), a Tet analog with lower antibiotic activity. The yabB::tetRA mutant was undetectable in liver or spleen of animals under normal diet, while in mice under diet including CTet, yabB::tetRA invaded at a level comparable to the WT in mice under normal diet. Moreover, yabB::tetRA produced a strong humoral-immunoresponse after one IP immunization with 10(6) bacteria, measured as serum reactivity against S. Typhimurium whole cell extract. By contrast, oral immunization with 10(6) bacteria was weaker and variable on inducing antibodies. Consistently, IP infected mice were fully protected in a challenge with 10(4) oral S. Typhimurium, while protection was partial in orally immunized mice. Our data indicate that S. Typhimurium yabB::tetRA is a conditionally attenuated strain capable of inducing a protective response in mice in non-permissive conditions. PMID:26792728

  5. Salmonella typhimurium-induced M1 macrophage polarization is dependent on the bacterial O antigen.

    PubMed

    Luo, Fengling; Sun, Xiaoming; Qu, Zhen; Zhang, Xiaolian

    2016-02-01

    Recently, macrophages were shown to be capable of differentiating toward two phenotypes after antigen stimulation: a classically activated (M1) or an alternatively activated phenotype (M2). To investigate the effect of Salmonella enteric serovar typhimurium (S. typhimurium) on macrophage differentiation, we compared macrophage phenotypes after infection of murine bone marrow-derived macrophages with wild-type S. typhimurium and its isogenic rfc mutant. S. typhimurium C5 induced M1 macrophage polarization and enhanced inducible nitric oxide synthase expression by macrophages; this induction was dependent on Toll-like receptor 4. In contrast, the Δrfc mutant (S. typhimurium C5 rfc::Km(r)) lost this function and induced an M2 response in the macrophages. Here, we propose that S. typhimurium C5 is capable of polarizing macrophages towards the M1 phenotype and that this polarization is dependent on the O antigen encoded by rfc. Our finding indicates that M1 macrophage polarization induced by S. typhimurium may be related to the ability of this intracellular bacterium to survive and replicate within macrophages, which is essential for systemic disease. PMID:26745982

  6. Survival, prophage induction, and invasive properties of lysogenic Salmonella Typhimurium exposed to simulated gastrointestinal conditions.

    PubMed

    Kim, Songrae; Ryu, Kanghee; Biswas, Debabrata; Ahn, Juhee

    2014-09-01

    This study was designed to evaluate the viability, prophage induction, invasive ability, and relative gene expression in lysogenic Salmonella Typhimurium exposed to the simulated gastric juice (SGJ) at pH 2 (SGJ-2), 3 (SGJ-3), 4 (SGJ-4), and 5 (SGJ-5) for 30 min followed by 0.5 % bile salts for 2 h. The susceptibility of lysogenic S. Typhimurium increased with decreasing pH value and increasing bile salt concentration. The lysogenic S. Typhimurium cells were least susceptible to SGJ-4 and SGJ-5, showing <1 log reduction. The highest prophage induction was observed by 3.34 log PFU/ml in lysogenic S. Typhimurium at SGJ-3 in the presence of 0.5 % bile salts. The numbers of invading lysogenic S. Typhimurium treated at SGJ-3, SGJ-4, and SGJ-5 were 3.57, 3.73, and 4.15 log CFU/cm(2), respectively. Most genes (hilA, hilC, hilD, invA, invE, invF, and sirA) were down-regulated in lysogenic S. Typhimurium treated at SGJ-3, SGJ-4, and SGJ-5. This study provides useful information for understanding physiological changes of lysogenic S. Typhimurium in the simulated gastrointestinal conditions. PMID:24929817

  7. A Murine Model to Study the Antibacterial Effect of Copper on Infectivity of Salmonella Enterica Serovar Typhimurium

    PubMed Central

    Sharan, Riti; Chhibber, Sanjay; Reed, Robert H.

    2011-01-01

    This study investigated the effect of copper as an antibacterial agent on the infectivity of Salmonella enterica serovar Typhimurium. Mice were infected orally with a standardized dose of unstressed Salmonella Typhimurium and copper-stressed cells of Salmonella Typhimurium. Bacterial counts in ileum, blood, liver and spleen were observed up to 168 h under normal aerobic conditions. Serum sensitivity, phagocytosis, malondialdehyde levels and histopathology were studied for both set of animals. A decreased bacterial count in the organs with mild symptoms of infection and a complete recovery by 48 h was observed in mice infected with copper-stressed bacteria. Histopathological examination of ileum tissue demonstrated regeneration of damaged tissue post-infection with copper-stressed bacteria and no malondialdehyde levels were detected after 24 h in ileum, spleen and liver. Exposure to copper sensitized Salmonella Typhimurium to the lytic action of serum and intracellular killing by peritoneal macrophages. It can be concluded that copper stress confers a decrease in the infectivity of healthy Salmonella Typhimurium in normal mice. This study highlights the significance of use of copper as an antibacterial agent against Salmonella Typhimurium in reducing the risk of incidence of Salmonella infections from contaminated water. PMID:21318012

  8. Growth and survival of antibiotic-resistant Salmonella typhimurium DT104 in liquid egg products.

    PubMed

    Musgrove, Michael T; Mcquestin, Olivia J; Tamplin, Mark; Kelley, Lynda C

    2009-09-01

    Since 11 September 2001, quality and food safety are no longer the concerns of only consumers, industry, regulatory agencies, or other government officials. Liquid foods that are prepared or stored in bulk, including liquid egg products, are considered to be at potential risk for sabotage. Because of their versatility, low price, and functional properties, many of these products are being marketed. Four of the most common products of this type are whole egg, egg albumen, 10% sugared yolk, and 10% salted yolk. Although all of the serotypes of Salmonella enterica may cause illness, multidrug-resistant Salmonella Typhimurium DT104 has become widespread and can cause severe illness that is difficult to treat. Studies were conducted to determine growth patterns of Salmonella Typhimurium DT104 in four commercial liquid egg products held at 4, 10, 20, 30, 37, and 42 degrees C for 0 to 384 h. All experiments were performed in duplicate and repeated twice. Standard methods were used to estimate cell numbers, and log CFU per gram of egg product was plotted against time. The number of cells of Salmonella Typhimurium DT104 increased to 8 to 9 log CFU/g in whole egg and 10% sugared yolk, increased by 1 log CFU/g in liquid albumen, but decreased by 3 log CFU/g in 10% salted yolk. Data from this study have been archived in the ComBase database to further assist policy makers or other scientists interested in Salmonella growth characteristics in liquid eggs. However, based on data generated in this study, Salmonella Typhimurium DT104 probably does not constitute a food threat agent in liquid eggs. PMID:19777905

  9. Evaluation of the respiratory route as a viable portal of entry for Salmonella in poultry via intratracheal challenge of Salmonella Enteritidis and Salmonella Typhimurium1

    PubMed Central

    Kallapura, G.; Morgan, M. J.; Pumford, N. R.; Bielke, L. R.; Wolfenden, A. D.; Faulkner, O. B.; Latorre, J. D.; Menconi, A.; Hernandez-Velasco, X.; Kuttappan, V. A.; Hargis, B. M.; Tellez, G.

    2014-01-01

    Experimental and epidemiological evidence suggests that primary infection of Salmonella is by the oral-fecal route for poultry. However, the airborne transmission of Salmonella and similar enteric zoonotic pathogens has been historically neglected. Increasing evidence of Salmonella bioaerosol generation in production facilities and studies suggesting the vulnerabilities of the avian respiratory architecture together have indicated the possibility of the respiratory system being a potential portal of entry for Salmonella in poultry. Presently, we evaluated this hypothesis through intratracheal (IT) administration of Salmonella Enteritidis and Salmonella Typhimurium, as separate challenges, in a total of 4 independent trials, followed by enumeration of cfu recovery in ceca-cecal tonsils and recovery incidence in liver and spleen. In all trials, both Salmonella Enteritidis and Salmonella Typhimurium, challenged IT colonized cecae to a similar or greater extent than oral administration at identical challenge levels. In most trials, chickens cultured for cfu enumeration from IT-challenged chicks at same dose as orally challenged, resulted in an increase of 1.5 log higher Salmonella Enteritidis from ceca-cecal tonsils and a much lower dose IT of Salmonella Enteritidis could colonize ceca to the same extent than a higher oral challenge. This trend of increased cecal colonization due to IT challenge was observed with all trails involving week-old birds (experiment 2 and 3), which are widely considered to be more difficult to infect via the oral route. Liver-spleen incidence data showed 33% of liver and spleen samples to be positive for Salmonella Enteritidis administered IT (106 cfu/chick), compared with 0% when administered orally (experiment 2, trial 1). Collectively, these data suggest that the respiratory tract may be a largely overlooked portal of entry for Salmonella infections in chickens. PMID:24570455

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  11. RNA-seq Brings New Insights to the Intra-Macrophage Transcriptome of Salmonella Typhimurium

    PubMed Central

    Hébrard, Magali; Colgan, Aoife; Owen, Siân V.; Sivasankaran, Sathesh K.; Cameron, Andrew D. S.; Hokamp, Karsten; Hinton, Jay C. D.

    2015-01-01

    Salmonella enterica serovar Typhimurium is arguably the world’s best-understood bacterial pathogen. However, crucial details about the genetic programs used by the bacterium to survive and replicate in macrophages have remained obscure because of the challenge of studying gene expression of intracellular pathogens during infection. Here, we report the use of deep sequencing (RNA-seq) to reveal the transcriptional architecture and gene activity of Salmonella during infection of murine macrophages, providing new insights into the strategies used by the pathogen to survive in a bactericidal immune cell. We characterized 3583 transcriptional start sites that are active within macrophages, and highlight 11 of these as candidates for the delivery of heterologous antigens from Salmonella vaccine strains. A majority (88%) of the 280 S. Typhimurium sRNAs were expressed inside macrophages, and SPI13 and SPI2 were the most highly expressed pathogenicity islands. We identified 31 S. Typhimurium genes that were strongly up-regulated inside macrophages but expressed at very low levels during in vitro growth. The SalComMac online resource allows the visualisation of every transcript expressed during bacterial replication within mammalian cells. This primary transcriptome of intra-macrophage S.-Typhimurium describes the transcriptional start sites and the transcripts responsible for virulence traits, and catalogues the sRNAs that may play a role in the regulation of gene expression during infection. PMID:26561851

  12. RNA-seq Brings New Insights to the Intra-Macrophage Transcriptome of Salmonella Typhimurium.

    PubMed

    Srikumar, Shabarinath; Kröger, Carsten; Hébrard, Magali; Colgan, Aoife; Owen, Siân V; Sivasankaran, Sathesh K; Cameron, Andrew D S; Hokamp, Karsten; Hinton, Jay C D

    2015-01-01

    Salmonella enterica serovar Typhimurium is arguably the world's best-understood bacterial pathogen. However, crucial details about the genetic programs used by the bacterium to survive and replicate in macrophages have remained obscure because of the challenge of studying gene expression of intracellular pathogens during infection. Here, we report the use of deep sequencing (RNA-seq) to reveal the transcriptional architecture and gene activity of Salmonella during infection of murine macrophages, providing new insights into the strategies used by the pathogen to survive in a bactericidal immune cell. We characterized 3583 transcriptional start sites that are active within macrophages, and highlight 11 of these as candidates for the delivery of heterologous antigens from Salmonella vaccine strains. A majority (88%) of the 280 S. Typhimurium sRNAs were expressed inside macrophages, and SPI13 and SPI2 were the most highly expressed pathogenicity islands. We identified 31 S. Typhimurium genes that were strongly up-regulated inside macrophages but expressed at very low levels during in vitro growth. The SalComMac online resource allows the visualisation of every transcript expressed during bacterial replication within mammalian cells. This primary transcriptome of intra-macrophage S.-Typhimurium describes the transcriptional start sites and the transcripts responsible for virulence traits, and catalogues the sRNAs that may play a role in the regulation of gene expression during infection. PMID:26561851

  13. Coptidis rhizome and Si Jun Zi Tang Can Prevent Salmonella enterica Serovar Typhimurium Infection in Mice

    PubMed Central

    Chang, Chiung-Hung; Yu, Bi; Su, Chiu-Hsian; Chen, Daniel S.; Hou, Yu-Chi; Chen, Yueh-Sheng; Hsu, Yuan-Man

    2014-01-01

    Salmonella, a common zoonotic pathogen, causes gastroenteritis in both humans and animals. Traditional Chinese Medicine (TCM) has been used to improve gastrointestinal dysfunction and to modify the immune response to inflammation for centuries. This study used six herbal plants and four TCM formulae to rate their efficacy in preventing S. Typhimurium infection via mouse model. Minimum bactericidal concentration (MBC) of Coptidis rhizome (CR) against the reference strain tallied 12.5 mg/ml and against clinical isolate ST21 was 25 mg/ml. MBCs of other herbal extracts and formulae on Salmonella Typhimurium strains were above 50 mg/ml. In the mice model, CR and Si Jun Zi Tang (SJZT) could significantly decrease the bacterial load in organs and blood after being challenged, along with body weight loss due to the infection. CR and SJZT alleviated infection-induced interferon-gamma levels in the serum and tissues, and tumor necrosis factor-alpha (TNF-α) levels in intestinal tissues. CR and SJZT serum metabolites could suppress S. Typhimurium invasion and TNF-α expression in RAW264.7 cells. The therapeutic activity of CR and SJZT may involve berberine, ginsenoside Rb1, and glycyrrhizin, interfering with Salmonella when invading macrophages. CR and SJZT has shown potential in preventing S. Typhimurium infection through the regulation of the immune response. PMID:25133542

  14. Systemic responses of BALB/c mice to Salmonella typhimurium infection.

    PubMed

    Zhu, Xiaoyang; Lei, Hehua; Wu, Junfang; Li, Jia V; Tang, Huiru; Wang, Yulan

    2014-10-01

    Salmonella typhimurium is a bacterial pathogen that poses a great threat to humans and animals. In order to discover hosts' responses to S. typhimurium infection, we collected and analyzed biofluids and organ tissues from mice which had ingested S. typhimurium. We employed (1)H NMR spectroscopy coupled with multivariate data analysis and immunological techniques. The results indicate that infection leads to a severe impact on mice spleen and ileum, which are characterized by splenomegaly and edematous villi, respectively. We found that increased levels of itaconic acid were correlated with the presence of splenomegaly during infection and may play an important role in Salmonella-containing vacuole acidification. In addition, metabonomic analyses of urine displayed the development of salmonellosis in mice, which is characterized by dynamic changes in energy metabolism. Furthermore, we found that the presence of S. typhimurium activated an anti-oxidative response in infected mice. We also observed changes in the gut microbial co-metabolites (hippurate, TMAO, TMA, methylamine). This investigation sheds much needed light on the host-pathogen interactions of S. typhimurium, providing further information to deepen our understanding of the long co-evolution process between hosts and infective bacteria. PMID:25209111

  15. Salmonella typhimurium infection triggers dendritic cells and macrophages to adopt distinct migration patterns in vivo.

    PubMed

    Zhao, Chunfang; Wood, Michael W; Galyov, Edouard E; Höpken, Uta E; Lipp, Martin; Bodmer, Helen C; Tough, David F; Carter, Robert W

    2006-11-01

    The presence of an anti-bacterial T cell response and evidence of bacterial products in inflamed joints of reactive arthritis patients suggests an antigen transportation role in this disease for macrophages and dendritic cells. We have investigated the functional properties and in vivo migration of macrophages and DC after infection with Salmonella enterica serovar Typhimurium (S. typhimurium). BM-derived macrophages and DC displayed enhanced expression of costimulatory molecules (CD40 and CD86) and increased production of pro-inflammatory cytokines (TNF-alpha, IL-6 and IL-12p40) and nitric oxide after infection. Upon adoptive transfer into mice, infected DC migrated to lymphoid tissues and induced an anti-Salmonella T cell response, whereas infected macrophages did not. Infection of DC with S. typhimurium was associated with strong up-regulation of the chemokine receptor CCR7 and acquisition of responsiveness to chemokines acting through this receptor. Moreover, S. typhimurium-infected CCR7-deficient DC were unable to migrate to lymph nodes after adoptive transfer, although they did reach the spleen. Our data demonstrate distinct roles for macrophages and DC as antigen transporters after S. typhimurium infection and a dependence on CCR7 for migration of DC to lymph nodes after bacterial infection. PMID:17048271

  16. 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

  17. Efficacy of a novel virulence gene-deleted Salmonella Typhimurium vaccine for protection against Salmonella infections in growing piglets.

    PubMed

    Hur, Jin; Song, Suck Oh; Lim, Jae Sam; Chung, In Kie; Lee, John Hwa

    2011-02-15

    We have previously developed a novel attenuated Salmonella Typhimurium (S. Typhimurium) ΔcpxR Δlon vaccine. This study was carried out to examine whether this vaccine could effectively protect growing piglets against Salmonella infection. Attenuated S. Typhimurium secreting the B subunit of Escherichia coli heat-labile enterotoxin was also used as a mucosal adjuvant. Pregnant sows in groups A and B were primed and boosted with the vaccine and mucosal adjuvant, whereas sows in groups C, D and E received PBS. Piglets in groups A and C were intramuscularly primed with formalin-inactivated vaccine and orally boosted with live vaccine, while piglets in groups B, D and E received PBS. Piglets in groups A, B, C, and D were challenged with a wild type virulent S. Typhimurium at the 11th weeks of age. Colostrum sIgA and IgG titers in vaccinated groups A and B sows were approximately 50 and 40 times higher than those of non-vaccinated groups C, D and E sows (P<0.001). Serum IgG titers of group A piglets were also significantly higher than those of groups D and E piglets during the study (P<0.001). Furthermore, no clinical signs were observed in group A piglets during the entire experimental period after the challenge, while diarrhea was observed in many of the piglets in groups B, C, and D. No Salmonella was isolated from fecal samples of the groups A and C piglets on day 14 after challenge, whereas the challenge strain was isolated from several piglets in groups B and D. These results indicate that vaccination of the piglets with the vaccine and mucosal adjuvant in addition to vaccination of their sows induced effective protection against Salmonella infections in the growing piglets. PMID:20869776

  18. Refined Live Attenuated Salmonella enterica Serovar Typhimurium and Enteritidis Vaccines Mediate Homologous and Heterologous Serogroup Protection in Mice

    PubMed Central

    Schmidlein, Patrick; Simon, Raphael; Pasetti, Marcela F.; Galen, James E.; Levine, Myron M.

    2015-01-01

    Invasive nontyphoidal Salmonella (NTS) infections constitute a major health problem among infants and toddlers in sub-Saharan Africa; these infections also occur in infants and the elderly in developed countries. We genetically engineered a Salmonella enterica serovar Typhimurium strain of multilocus sequence type 313, the predominant genotype circulating in sub-Saharan Africa. We evaluated the capacities of S. Typhimurium and Salmonella enterica serovar Enteritidis ΔguaBA ΔclpX live oral vaccines to protect mice against a highly lethal challenge dose of the homologous serovar and determined protection against other group B and D serovars circulating in sub-Saharan Africa. The vaccines S. Typhimurium CVD 1931 and S. Enteritidis CVD 1944 were immunogenic and protected BALB/c mice against 10,000 50% lethal doses (LD50) of S. Typhimurium or S. Enteritidis, respectively. S. Typhimurium CVD 1931 protected mice against the group B serovar Salmonella enterica serovar Stanleyville (91% vaccine efficacy), and S. Enteritidis CVD 1944 protected mice against the group D serovar Salmonella enterica serovar Dublin (85% vaccine efficacy). High rates of survival were observed when mice were infected 12 weeks postimmunization, indicating that the vaccines elicited long-lived protective immunity. Whereas CVD 1931 did not protect against S. Enteritidis R11, CVD 1944 did mediate protection against S. Typhimurium D65 (81% efficacy). These findings suggest that a bivalent (S. Typhimurium and S. Enteritidis) vaccine would provide broad protection against the majority of invasive NTS infections in sub-Saharan Africa. PMID:26351285

  19. Refined live attenuated Salmonella enterica serovar Typhimurium and Enteritidis vaccines mediate homologous and heterologous serogroup protection in mice.

    PubMed

    Tennant, Sharon M; Schmidlein, Patrick; Simon, Raphael; Pasetti, Marcela F; Galen, James E; Levine, Myron M

    2015-12-01

    Invasive nontyphoidal Salmonella (NTS) infections constitute a major health problem among infants and toddlers in sub-Saharan Africa; these infections also occur in infants and the elderly in developed countries. We genetically engineered a Salmonella enterica serovar Typhimurium strain of multilocus sequence type 313, the predominant genotype circulating in sub-Saharan Africa. We evaluated the capacities of S. Typhimurium and Salmonella enterica serovar Enteritidis ΔguaBA ΔclpX live oral vaccines to protect mice against a highly lethal challenge dose of the homologous serovar and determined protection against other group B and D serovars circulating in sub-Saharan Africa. The vaccines S. Typhimurium CVD 1931 and S. Enteritidis CVD 1944 were immunogenic and protected BALB/c mice against 10,000 50% lethal doses (LD50) of S. Typhimurium or S. Enteritidis, respectively. S. Typhimurium CVD 1931 protected mice against the group B serovar Salmonella enterica serovar Stanleyville (91% vaccine efficacy), and S. Enteritidis CVD 1944 protected mice against the group D serovar Salmonella enterica serovar Dublin (85% vaccine efficacy). High rates of survival were observed when mice were infected 12 weeks postimmunization, indicating that the vaccines elicited long-lived protective immunity. Whereas CVD 1931 did not protect against S. Enteritidis R11, CVD 1944 did mediate protection against S. Typhimurium D65 (81% efficacy). These findings suggest that a bivalent (S. Typhimurium and S. Enteritidis) vaccine would provide broad protection against the majority of invasive NTS infections in sub-Saharan Africa. PMID:26351285

  20. Rapid detection of Escherichia coli and Salmonella typhimurium by surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Su, Lan; Zhang, Ping; Zheng, Da-wei; Wang, Yang-jun-qi; Zhong, Ru-gang

    2015-03-01

    In this paper, the surface-enhanced Raman scattering (SERS) is used as an analytical tool for the detection and identification of pathogenic bacteria of Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium). Compared with normal Raman signal, the intensity of SERS signal is greatly enhanced. After processing all SERS data, the obvious differences between the SERS spectra of two species are determined. And applying the chemometric tools of principal component analysis and hierarchical cluster analysis (PCA-HCA), the SERS spectra of two species are distinguished more accurately. The results indicate that SERS analysis can provide a rapid and sensitive method for the detection of pathogenic bacteria.

  1. Characterization of lip expression in Salmonella typhimurium: analysis of lip::lac operon fusions.

    PubMed

    Smith, R L; Pelley, J W; Jeter, R M

    1991-10-01

    Strains of Salmonella typhimurium which have an auxotrophic requirement for lipoic acid were isolated by mutagenesis with the transposable element Mu dJ. The chromosomal location of these insertion mutations was determined to be at 14 map units by bacteriophage P22-mediated cotransduction. The lip gene is transcribed in the clockwise direction relative to the S. typhimurium genetic map. Strains with lip::lac operon fusions were used to characterize the transcriptional activity of the lip promoter. Transcription of the lip gene is not regulated by catabolite repression or lipoic acid concentration. The data indicate that the lip gene product is expressed constitutively at a low level. PMID:1663151

  2. Complete genome sequence of Salmonella enterica serovar typhimurium bacteriophage SPN1S.

    PubMed

    Shin, Hakdong; Lee, Ju-Hoon; Lim, Jeong-A; Kim, Hyeryen; Ryu, Sangryeol

    2012-01-01

    To understand the interaction between the host of pathogenic Salmonella enterica serovar Typhimurium and its bacteriophage, we isolated the bacteriophage SPN1S. It is a lysogenic phage in the Podoviridae family and uses the O-antigen of lipopolysaccharides (LPS) as a host receptor. Comparative genomic analysis of phage SPN1S and the S. enterica serovar Anatum-specific phage ε15 revealed different host specificities, probably due to the low homology of host specificity-related genes. Here we report the complete circular genome sequence of S. Typhimurium-specific bacteriophage SPN1S and show the results of our analysis. PMID:22205721

  3. Emergence of clinical Salmonella enterica serovar Typhimurium isolates with concurrent resistance to ciprofloxacin, ceftriaxone, and azithromycin.

    PubMed

    Wong, Marcus Ho Yin; Yan, Meiying; Chan, Edward Wai Chi; Biao, Kan; Chen, Sheng

    2014-07-01

    Salmonella infection is an important public health issue for which the needs of antimicrobial treatment are increasing. A total of 546 human clinical S. enterica serovar Typhimurium isolates were recovered from patients in hospitals in China during the period of 2005 to ∼ 2011. Twenty percent of the isolates exhibited resistance to ciprofloxacin, and 4% were resistant to ceftriaxone. Importantly, for the first time, 12 (2%) S. Typhimurium isolates resistant to both ciprofloxacin and ceftriaxone were recovered; among these 12 isolates, two were also resistant to azithromycin, and one was resistant to all other drugs tested. The combined effects of various transferrable extended-spectrum β-lactamase determinants and a novel efflux-based ciprofloxacin resistance mechanism encoded by the mobile efflux gene oqxAB were responsible for the emergence of these extremely (highly) drug-resistant (XDR) S. Typhimurium isolates. The dissemination of resistance genes, such as those encoding ESBLs and the OqxAB pump, among Salmonella organisms will speed up the selection of XDR Salmonella, posing a huge threat to public health and Salmonella infection control. PMID:24752251

  4. Quantitative evaluation of E. coli F4 and Salmonella Typhimurium binding capacity of yeast derivatives

    PubMed Central

    2013-01-01

    The target of the present study was to quantify the capacity of different commercially available yeast derivatives to bind E. coli F4 and Salmonella Typhimurium. In addition, a correlation analysis was performed for the obtained binding numbers and the mannan-, glucan- and protein contents of the products, respectively. In a subsequent experiment, different yeast strains were fermented and treated by autolysis or French press to obtain a concentrated yeast cell wall. The capacity of yeast cell wall products to bind E. coli F4 and Salmonella Typhimurium was assessed with a quantitative microbiological microplate-based assay by measuring the optical density (OD) as the growth parameter of adhering bacteria. Total mannan and glucan were determined by HPLC using an isocratic method and a Refractive Index (RI) Detector. Total protein was determined by Total Kjeldahl Nitrogen (TKN). Statistical analyses were performed with IBM SPSS V19 using Spearman correlation and Mann Whitney U Test. Different yeast derivatives show different binding numbers, which indicate differences in product quality. Interestingly, the binding numbers for Salmonella Typhimurium are consistently higher (between one and two orders of magnitude) than for E. coli F4. We could demonstrate some statistical significant correlations between the mannan- and glucan content of different yeast derivatives and pathogen binding numbers; however, for the different yeast strains fermented under standardized laboratory conditions, no statistically significant correlations between the mannan- and glucan content and the binding numbers for E. coli and Salmonella Typhimurium were found. Interestingly, we could demonstrate that the yeast autolysis had a statistically significant difference on E. coli binding in contrast to the French press treatment. Salmonella binding was independent of these two treatments. As such, we could not give a clear statement about the binding factors involved. We propose that many more

  5. Antigenic Modification, Rosette-Forming Cells, and Salmonella typhimurium Resistance in Outbred and Inbred Mice

    PubMed Central

    Bigley, Nancy J.; Kreps, David P.; Smith, Randall A.; Esa, Ahmed

    1981-01-01

    To assess the separate contributions of host T cells and the physical state of the antigen in the development of effective. Salmonella resistance, glutaraldehyde-treated and untreated protein- and ribonucleic acid-rich extracts (E-RNA extracts) of virulent Salmonella typhimurium SR-11 or attenuated S. typhimurium RIA were used to immunize Salmonella-resistant Salmonella-susceptible strains of mice for the purpose of determining whether antigen-specific T-cell or B-cell responses were formed and, if so, which responses predominated. The resistance imparted to each mouse strain after vaccination with S. typhimurium RIA was used as the standard for comparison. The inbred mouse strains C57BL/6 and DBA/2 and their F1 hybrid (strain BDF1), outbred ICR Swiss mice, and endotoxin-resistant C3H/HeJ mice were examined for the capacity to develop resistance to lethal Salmonella infections, as well as the ability to generate antigen-reactive T cells. Only the BDF1, C3H/HeJ, and ICR Swiss mice were able to develop resistance to challenge infections mediated by the virulent SR-11 strain of S. typhimurium after vaccination with the living, attenuated RIA strain of S. typhimurium or immunization with E-RNA extracts. We developed an assay to identify the antigen-reactive rosette-forming lymphocytes present in lymph nodes and spleens of immunized mice. Levels of 0.2% or higher of theta antigen-bearing, antigen-reactive rosette-forming cells were found in the lymph nodes or spleens or both of only the BDF1, C3H/HeJ, and ICR Swiss mice (i.e., in the “Salmonella responder” strains). Mouse strains C57BL/6 and DBA/2, which failed to develop resistance to lethal infections after immunization with the S. typhimurium RIA vaccine or with the E-RNA extracts, lacked effective numbers of antitheta antigen-sensitive rosette-forming cells. Modification of the effective E-RNA extracts by polymerization with glutaraldehyde resulted in a marked diminution in their abilities to induce resistance

  6. The Molecular Epidemiological Characteristics and Genetic Diversity of Salmonella Typhimurium in Guangdong, China, 2007–2011

    PubMed Central

    Huang, Yanhui; He, Dongmei; Li, Xiaocui; Liang, Zhaoming; Ke, Changwen

    2014-01-01

    Background Salmonella enterica serovar Typhimurium is the most important serovar associated with human salmonellosis worldwide. Here we aimed to explore the molecular epidemiology and genetic characteristics of this serovar in Guangdong, China. Methodology We evaluated the molecular epidemiology and genetic characteristics of 294 endemic Salmonella Typhimurium clinical isolates which were collected from 1977 to 2011 in Guangdong, China, and compared them with a global set of isolates of this serovar using epidemiological data and Multilocus Sequence Typing (MLST) analysis. Principal Finding The 294 isolates were assigned to 13 Sequencing types (STs) by MLST, of which ST34 and ST19 were the most common in Guangdong. All the STs were further assigned to two eBurst Groups, eBG1 and eBG138. The eBG1 was the major group endemic in Guangdong. Nucleotide and amino acid variability were comparable for all seven MLST loci. Tajima’s D test suggested positive selection in hisD and thrA genes (p<0.01), but positive selection was rejected for the five other genes (p>0.05). In addition, The Tajima’s D test within each eBG using the global set of isolates showed positive selection in eBG1 and eBG138 (p<0.05), but was rejected in eBG243 (p>0.05). We also analyzed the phylogenetic structure of Salmonella Typhimurium from worldwide sources and found that certain STs are geographically restricted. ACSSuT was the predominant multidrug resistance pattern for this serovar. The resistant profiles ACSSuTTmNaG, ACSSuTTmNa and ACSuTTmNaG seem to be specific for ST34, and ASSuTNa for ST19. Conclusion Here we presented a genotypic characterization of Salmonella Typhimurium isolates using MLST and found two major STs are endemic in Guangdong. Our analyses indicate that genetic selection may have shaped the Salmonella Typhimurium populations. However, further evaluation with additional isolates from various sources will be essential to reveal the scope of the epidemiological characteristics

  7. Mitsuokella jalaludinii inhibits growth of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella continues to be a significant human health threat, and the objective of this study was to identify microorganisms with the potential to improve porcine food-safety through their antagonism of Salmonella. Anaerobic culture supernatants of 973 bacterial isolates from the gastrointestinal tr...

  8. Mitsuokella jalaludinii inhibits growth of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella continues to be a significant human health threat, and the objective of this study was to identify microorganisms with the potential to improve porcine food-safety through their antagonism of Salmonella. Anaerobic culture supernates of 973 bacterial isolates from the gastrointestinal trac...

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

    PubMed Central

    Octavia, Sophie; Wang, Qinning; Tanaka, Mark M.

    2015-01-01

    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. PMID:26311853

  10. Ribosomal ribonucleic acid isolated from Salmonella typhimurium: absence of the intact 23S species.

    PubMed Central

    Winkler, M E

    1979-01-01

    Ribonucleic acid (RNA) isolated by four distinct methods and from a variety of Salmonella typhimurium strains lacked intact 23S ribosomal RNA (rRNA). On sucrose gradients which minimize aggregation, the vast majority of S. typhimurium rRNA sedimented as a 16S peak with a 14S shoulder. RNA from this region of the gradient was resolved into three discrete bands by electrophoresis in formamide. Two very minor S. typhimurium RNA peaks were resolved at 21S and 10S on sucrose gradients, and each peak formed discrete bands in electrophoresis. It is concluded that if S. typhimurium does possess an intact 23S rRNA species, this species is extremely "labile." The absence of isolatable S. typhimurium 23S rRNA possibly reflected in vivo processing of the rRNA before isolation. Under certain conditions, S. typhimurium rRNA formed discrete aggregates which sedimented similarly to intact Escherichia coli 23S rRNA. Images PMID:383696

  11. The elimination of Salmonella typhimurium in sewage sludge by aerobic mesophilic stabilization and lime hydrated stabilization.

    PubMed

    Plachá, Iveta; Venglovský, Ján; Maková, Zuzana; Martinéz, José

    2008-07-01

    This study observed the effects of two methods, aerobic mesophilic stabilization and lime hydrated stabilization of sewage sludge upon the survival of Salmonella typhimurium. Raw (primary) sludges from the mechanical biological municipal sewage treatment plant were used. Aerobic stabilization and lime hydrated stabilization were carried out in a laboratory fermentor. Aerobic stabilization was carried out in the mesophilic temperature range (from 25.70+/-0.40 to 37.82+/-1.38 degrees C). Lime hydrated was used at an amount of 10 kg/m(3) for the stabilization. Sludge samples were inoculated with a broth culture of S. typhimurium. Quantitative and qualitative examinations of the presence of S. typhimurium were carried out. Aerobic mesophilic stabilization caused elimination S. typhimurium within 48 h. The T(90) value of S. typhimurium was 6.66+/-0.20 h. During the lime hydrated stabilization pH values significantly increased from 5.66+/-0.07 to 12.12+/-0.02 (P<0.01). S. typhimurium was inactivated within 1h and the T(90) value was 0.19+/-0.01 h. Our study confirmed that the treatment of sewage sludge with lime hydrated was significantly more effective than the aerobic mesophilic stabilization, (P<0.01). PMID:17931859

  12. Bioprobes Based on Aptamer and Silica Fluorescent Nanoparticles for Bacteria Salmonella typhimurium Detection.

    PubMed

    Wang, Qiu-Yue; Kang, Yan-Jun

    2016-12-01

    In this study, we have developed an efficient method based on single-stranded DNA (ssDNA) aptamers along with silica fluorescence nanoparticles for bacteria Salmonella typhimurium detection. Carboxyl-modified Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate (RuBPY)-doped silica nanoparticles (COOH-FSiNPs) were prepared using reverse microemulsion method, and the streptavidin was conjugated to the surface of the prepared COOH-FSiNPs. The bacteria S. typhimurium was incubated with a specific ssDNA biotin-labeled aptamer, and then the aptamer-bacteria conjugates were treated with the synthetic streptavidin-conjugated silica fluorescence nanoprobes (SA-FSiNPs). The results under fluorescence microscopy show that SA-FSiNPs can be applied effectively for the labeling of bacteria S. typhimurium with great photostable property. To further verify the specificity of SA-FSiNPs out of multiple bacterial conditions, variant concentrations of bacteria mixtures composed of bacteria S. typhimurium, Escherichia coli, and Bacillus subtilis were treated with SA-FSiNPs.In addition, the feasibility of SA-FSiNPs for bacteria S. typhimurium detection in chicken samples was assessed. All the results display that the established aptamer-based nanoprobes exhibit the superiority for bacteria S. typhimurium detection, which is referentially significant for wider application prospects in pathogen detection. PMID:26983430

  13. 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.

  14. Decreased intracellular survival of an fkpA mutant of Salmonella typhimurium Copenhagen.

    PubMed

    Horne, S M; Kottom, T J; Nolan, L K; Young, K D

    1997-02-01

    The fkpA gene of Salmonella typhimurium encodes a protein similar to the macrophage infectivity potentiator (Mip) proteins of Legionella pneumophila and Chlamydia trachomatis. Because Mip proteins enhance the ability of these intracellular pathogens to survive within macrophages and epithelial cells, we tested whether the product of the fkpA gene would have the same effect on the intracellular growth of a virulent strain of S. typhimurium. By a series of P22 transductions, the fkpA gene of S. typhimurium Copenhagen was replaced with the inactive fkpA1::omega-Cm gene from Escherichia coli, creating the mutant S. typhimurium KY32H1. The Copenhagen and KY32H1 strains were equally able to enter Caco-2 cells (an epithelial cell line) and J774.A1 cells (a macrophage-like cell line). However, compared to the parent, the fkpA mutant survived less well in both types of cells during the first 6 h after infection. The number of viable intracellular S. typhimurium Copenhagen bacteria remained constant 6 h after infection of Caco-2 cells, but the viability of S. typhimurium KY32H1 decreased significantly by 4 h postinfection. The fkpA mutant also exhibited a reduced ability to survive intracellularly in J774.A1 cells as little as 2 h postinfection. Complementation of the fkpA mutation by a plasmid-borne wild-type fkpA gene from E. coli restored the ability of S. typhimurium KY32H1 to grow normally in J774.A1 cells. Thus, expression of the mip-like fkpA gene confers on S. typhimurium Copenhagen properties analogous to those mediated by the Mip proteins in other intracellular pathogens, suggesting that this mechanism may play a role in the virulence and/or intracellular growth of numerous bacteria. PMID:9009347

  15. 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. PMID:19729455

  16. High-throughput Assay to Phenotype Salmonella enterica Typhimurium Association, Invasion, and Replication in Macrophages

    PubMed Central

    Wu, Jing; Pugh, Roberta; Laughlin, Richard C.; Andrews-Polymenis, Helene; McClelland, Michael; Bäumler, Andreas J.; Adams, L. Garry

    2014-01-01

    Salmonella species are zoonotic pathogens and leading causes of food borne illnesses in humans and livestock1. Understanding the mechanisms underlying Salmonella-host interactions are important to elucidate the molecular pathogenesis of Salmonella infection. The Gentamicin protection assay to phenotype Salmonella association, invasion and replication in phagocytic cells was adapted to allow high-throughput screening to define the roles of deletion mutants of Salmonella enterica serotype Typhimurium in host interactions using RAW 264.7 murine macrophages. Under this protocol, the variance in measurements is significantly reduced compared to the standard protocol, because wild-type and multiple mutant strains can be tested in the same culture dish and at the same time. The use of multichannel pipettes increases the throughput and enhances precision. Furthermore, concerns related to using less host cells per well in 96-well culture dish were addressed. Here, the protocol of the modified in vitro Salmonella invasion assay using phagocytic cells was successfully employed to phenotype 38 individual Salmonella deletion mutants for association, invasion and intracellular replication. The in vitro phenotypes are presented, some of which were subsequently confirmed to have in vivo phenotypes in an animal model. Thus, the modified, standardized assay to phenotype Salmonella association, invasion and replication in macrophages with high-throughput capacity could be utilized more broadly to study bacterial-host interactions. PMID:25146526

  17. Activation of inflammasome by attenuated Salmonella typhimurium in bacteria-mediated cancer therapy.

    PubMed

    Phan, Thuy Xuan; Nguyen, Vu Hong; Duong, Mai Thi-Quynh; Hong, Yeongjin; Choy, Hyon E; Min, Jung-Joon

    2015-11-01

    Escherichia coli and attenuated Salmonella both naturally accumulate in a tumor mass, yet have distinct therapeutic efficacy: the E. coli K-12 strain (MG1655) cannot induce as significant a tumor suppression as attenuated Salmonella typhimurium, despite similar levels of accumulation in the tumor. To elucidate the mechanism of the robust antitumor effect of S. typhimurium, the cytokine profiles elicited by bacterial colonization in tumors were analyzed. C57BL/6 mice bearing MC38 tumors were injected with Salmonella or MG1655 in the tail vein. Tumors were collected 3 days post-infection and homogenized. Inflammasome-related signals were measured by real-time PCR, ELISA and western blot analysis. Only attenuated Salmonella triggered significant levels of the inflammatory cytokine IL-1β in the tumor, whereas tumor growth was significantly suppressed. In addition, transcript levels of the core molecules of inflammasome signaling, IPAF, NLRP3 and P2X7, were significantly elevated only in Salmonella-treated tumors. Upon direct interaction between Salmonella and BMDM, BMDM expressed inflammasome-related proteins such as NLRP3, IPAF and caspase-1 p10, and secreted a significant amount of IL-1β in supernatants. Coincubation assays with BMDM and Salmonella-treated MC38 cells (damaged cancer cells) revealed secretion of IL-1β only when TLR4 and inflammasome were activated by both LPS and damaged cancer cells. ATP released from damaged cancer cells was also identified as a mechanism of NLRP3 activation. In conclusion, Salmonella activate the inflammasome pathway using damage signals released from cancer cells and through direct interaction with macrophages. PMID:26500022

  18. Microevolution of Monophasic Salmonella Typhimurium during Epidemic, United Kingdom, 2005–2010

    PubMed Central

    Petrovska, Liljana; Mather, Alison E.; AbuOun, Manal; Branchu, Priscilla; Harris, Simon R.; Connor, Thomas; Hopkins, K.L.; Underwood, A.; Lettini, Antonia A.; Page, Andrew; Bagnall, Mary; Wain, John; Parkhill, Julian; Dougan, Gordon; Davies, Robert

    2016-01-01

    Microevolution associated with emergence and expansion of new epidemic clones of bacterial pathogens holds the key to epidemiologic success. To determine microevolution associated with monophasic Salmonella Typhimurium during an epidemic, we performed comparative whole-genome sequencing and phylogenomic analysis of isolates from the United Kingdom and Italy during 2005–2012. These isolates formed a single clade distinct from recent monophasic epidemic clones previously described from North America and Spain. The UK monophasic epidemic clones showed a novel genomic island encoding resistance to heavy metals and a composite transposon encoding antimicrobial drug resistance genes not present in other Salmonella Typhimurium isolates, which may have contributed to epidemiologic success. A remarkable amount of genotypic variation accumulated during clonal expansion that occurred during the epidemic, including multiple independent acquisitions of a novel prophage carrying the sopE gene and multiple deletion events affecting the phase II flagellin locus. This high level of microevolution may affect antigenicity, pathogenicity, and transmission. PMID:26982594

  19. Large outbreak of food poisoning caused by Salmonella typhimurium definitive type 49 in mayonnaise.

    PubMed Central

    Mitchell, E.; O'Mahony, M.; Lynch, D.; Ward, L. R.; Rowe, B.; Uttley, A.; Rogers, T.; Cunningham, D. G.; Watson, R.

    1989-01-01

    An investigation was conducted to determine the vehicle of infection of an outbreak of food poisoning in a large metropolitan building early in 1988. A questionnaire was distributed to 700 people who had eaten in the building during the week of the outbreak, and attack rates for specific food were calculated. Food and stool samples, environmental samples, and eggs and environmental swabs from the egg suppliers were examined microbiologically. Altogether 474 questionnaires were returned, 120 people reporting gastrointestinal illness. The illness was significantly associated with foods containing mayonnaise. Salmonella typhimurium definitive type 49 was isolated from 76 of the 84 stool samples containing salmonella and from five of the eight samples taken from the chicken house of the main egg supplier. Mayonnaise was probably the vehicle of infection, which was caused by S typhimurium definitive type 49. PMID:2493310

  20. Microevolution of Monophasic Salmonella Typhimurium during Epidemic, United Kingdom, 2005-2010.

    PubMed

    Petrovska, Liljana; Mather, Alison E; AbuOun, Manal; Branchu, Priscilla; Harris, Simon R; Connor, Thomas; Hopkins, K L; Underwood, A; Lettini, Antonia A; Page, Andrew; Bagnall, Mary; Wain, John; Parkhill, Julian; Dougan, Gordon; Davies, Robert; Kingsley, Robert A

    2016-04-01

    Microevolution associated with emergence and expansion of new epidemic clones of bacterial pathogens holds the key to epidemiologic success. To determine microevolution associated with monophasic Salmonella Typhimurium during an epidemic, we performed comparative whole-genome sequencing and phylogenomic analysis of isolates from the United Kingdom and Italy during 2005-2012. These isolates formed a single clade distinct from recent monophasic epidemic clones previously described from North America and Spain. The UK monophasic epidemic clones showed a novel genomic island encoding resistance to heavy metals and a composite transposon encoding antimicrobial drug resistance genes not present in other Salmonella Typhimurium isolates, which may have contributed to epidemiologic success. A remarkable amount of genotypic variation accumulated during clonal expansion that occurred during the epidemic, including multiple independent acquisitions of a novel prophage carrying the sopE gene and multiple deletion events affecting the phase II flagellin locus. This high level of microevolution may affect antigenicity, pathogenicity, and transmission. PMID:26982594

  1. Biocontrol of Salmonella Typhimurium in RTE foods with the virulent bacteriophage FO1-E2.

    PubMed

    Guenther, Susanne; Herzig, Oliver; Fieseler, Lars; Klumpp, Jochen; Loessner, Martin J

    2012-03-01

    Foodborne Salmonella infections are a major public health concern worldwide. Bacteriophages offer highly specific and effective biocontrol of such pathogens. We evaluated the broad host range, virulent phage FO1-E2 for reduction of Salmonella Typhimurium in different RTE foods. Samples were spiked with 1×10³ Salmonella cells and treated with 3×10⁸ pfu/g phage, and incubated for 6 days at 8 °C or 15 °C. At 8 °C, no viable cells remained following FO1-E2 application, corresponding to a more than 3 log₁₀ unit reduction. At 15 °C, application of phage lowered S. Typhimurium counts by 5 log units on turkey deli meat and in chocolate milk, and by 3 logs on hot dogs and in seafood. In egg yolk, an effect was observed only after 2 days, but not after 6 days. Phage particles retained their infectivity, although they were readily immobilized by the food matrix, resulting in loss of their ability to diffuse and infect target cells. At the end of the incubation period, phage-resistant Salmonella strains appeared which, however, were not able to compensate for the initial killing effect. Altogether, our data show that virulent phages such as FO1-E2 offer an effective biocontrol measure for Salmonella in foods. PMID:22244192

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

    PubMed

    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 x 10(8) 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

  3. Salmonella typhimurium Suppresses Tumor Growth via the Pro-Inflammatory Cytokine Interleukin-1β

    PubMed Central

    Kim, Jung-Eun; Phan, Thuy Xuan; Nguyen, Vu Hong; Dinh-Vu, Hong-Van; Zheng, Jin Hai; Yun, Misun; Park, Sung-Gyoo; Hong, Yeongjin; Choy, Hyon E.; Szardenings, Michael; Hwang, Won; Park, Jin-A; Park, SunHee; Im, Sin-Hyeog; Min, Jung-Joon

    2015-01-01

    Although strains of attenuated Salmonella typhimurium and wild-type Escherichia coli show similar tumor-targeting capacities, only S. typhimurium significantly suppresses tumor growth in mice. The aim of the present study was to examine bacteria-mediated immune responses by conducting comparative analyses of the cytokine profiles and immune cell populations within tumor tissues colonized by E. coli or attenuated Salmonellae. CT26 tumor-bearing mice were treated with two different bacterial strains: S. typhimurium defective in ppGpp synthesis (ΔppGpp Salmonellae) or wild-type E. coli MG1655. Cytokine profiles and immune cell populations in tumor tissue colonized by these two bacterial strains were examined at two time points based on the pattern of tumor growth after ΔppGpp Salmonellae treatment: 1) when tumor growth was suppressed ('suppression stage') and 2) when they began to re-grow ('re-growing stage'). The levels of IL-1β and TNF-α were markedly increased in tumors colonized by ΔppGpp Salmonellae. This increase was associated with tumor regression; the levels of both IL-1β and TNF-α returned to normal level when the tumors started to re-grow. To identify the immune cells primarily responsible for Salmonellae-mediated tumor suppression, we examined the major cell types that produce IL-1β and TNF-α. We found that macrophages and dendritic cells were the main producers of TNF-α and IL-1β. Inhibiting IL-1β production in Salmonellae-treated mice restored tumor growth, whereas tumor growth was suppressed for longer by local administration of recombinant IL-1β or TNF-α in conjunction with Salmonella therapy. These findings suggested that IL-1β and TNF-α play important roles in Salmonella-mediated cancer therapy. A better understanding of host immune responses in Salmonella therapy may increase the success of a given drug, particularly when various strategies are combined with bacteriotherapy. PMID:26516371

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

    PubMed

    Hernandez, Sonia M; Keel, Kevin; Sanchez, Susan; Trees, Eija; Gerner-Smidt, Peter; Adams, Jennifer K; Cheng, Ying; Ray, Al; Martin, Gordon; Presotto, Andrea; Ruder, Mark G; Brown, Justin; Blehert, David S; Cottrell, Walter; Maurer, John J

    2012-10-01

    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. PMID:22885752

  5. Impact of phytopathogen infection and extreme weather stress on internalization of Salmonella Typhimurium in lettuce.

    PubMed

    Ge, Chongtao; Lee, Cheonghoon; Nangle, Ed; Li, Jianrong; Gardner, David; Kleinhenz, Matthew; Lee, Jiyoung

    2014-01-01

    Internalization of human pathogens, common in many types of fresh produce, is a threat to human health since the internalized pathogens cannot be fully inactivated/removed by washing with water or sanitizers. Given that pathogen internalization can be affected by many environmental factors, this study was conducted to investigate the influence of two types of plant stress on the internalization of Salmonella Typhimurium in iceberg lettuce during pre-harvest. The stresses were: abiotic (water stress induced by extreme weather events) and biotic (phytopathogen infection by lettuce mosaic virus [LMV]). Lettuce with and without LMV infection were purposefully contaminated with green fluorescence protein-labeled S. Typhimurium on the leaf surfaces. Lettuce was also subjected to water stress conditions (drought and storm) which were simulated by irrigating with different amounts of water. The internalized S. Typhimurium in the different parts of the lettuce were quantified by plate count and real-time quantitative PCR and confirmed with a laser scanning confocal microscope. Salmonella internalization occurred under the conditions outlined above; however internalization levels were not significantly affected by water stress alone. In contrast, the extent of culturable S. Typhimurium internalized in the leafy part of the lettuce decreased when infected with LMV under water stress conditions and contaminated with high levels of S. Typhimurium. On the other hand, LMV-infected lettuce showed a significant increase in the levels of culturable bacteria in the roots. In conclusion, internalization was observed under all experimental conditions when the lettuce surface was contaminated with S. Typhimurium. However, the extent of internalization was only affected by water stress when lettuce was infected with LMV. PMID:24220663

  6. 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; Peter Gerner-Smidt

    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.

  7. LUMO energies and hydrophobicity as determinants of mutagenicity by nitroaromatic compounds in Salmonella typhimurium

    SciTech Connect

    Lopez de Compadre, R.L.; Debnath, A.K.; Hansch, C. ); Shusterman, A.J. )

    1990-01-01

    Quantitative structure-activity relationships have been derived for the mutagenic activity of 47 nitroaromatic compounds acting on Salmonella typhimurium (TA100) and 66 acting on TA98. The mutagenicity is linearly dependent on the energy of the lowest occupied molecular orbital and bilinearly dependent on the hydrophobicity (octanol/water log P) of the mutagens. The mechanism of action is considered in the light of these findings.

  8. Draft Genome Sequences of Salmonella enterica subsp. enterica Serovars Typhimurium and Nottingham Isolated from Food Products

    PubMed Central

    Zheng, Jie; Ayers, Sherry; Melka, David C.; Curry, Phillip E.; Payne, Justin S.; Laasri, Anna; Wang, Charles; Hammack, Thomas S.; Brown, Eric W.

    2016-01-01

    A quantitative real-time PCR (qPCR) designed to detect Salmonella enterica subsp. enterica serovar Enteritidis, targeting the sdf gene, generated positive results for S. enterica subsp. enterica serovar Typhimurium (CFSAN033950) and S. enterica subsp. enterica serovar Nottingham (CFSAN006803) isolated from food samples. Both strains show pulsed-field gel electrophoresis (PFGE) patterns distinct from those of S. Enteritidis. Here, we report the genome sequences of these two strains. PMID:27445384

  9. Acetohydroxy acid synthase isoenzymes of Escherichia coli K12 and Salmonella typhimurium.

    PubMed

    de Felice, M; Lago, C T; Squires, C H; Calvo, J M

    1982-01-01

    In Escherichia coli K12 and in Salmonella typhimurium the first step common to the biosynthesis of isoleucine, leucine and valine is catalyzed by an intriguing system of isoenzymes. Two of these are normally expressed, while the genetic determinant for a third one is transcribed, but not translated as an active polypeptide. We analyze here the significance of this system in the light of the most recent results. PMID:6805381

  10. Evaluation of alternariol and alternariol methyl ether for mutagenic activity in Salmonella typhimurium

    SciTech Connect

    Davis, V.M.; Stack, M.E. )

    1994-10-01

    Alternariol and alternariol methyl ether were tested in the Ames Salmonella typhimurium assay, and both were shown, with and without metabolic activation, to be nonmutagenic to strains TA98 and TA100. The finding of other investigators that alternariol methyl ether is weakly mutagenic to Ta98 without metabolic activation could have resulted from the presence of a small amount of one of the highly mutagenic altertoxins in the alternariol methyl ether originally tested. 9 refs., 3 figs., 1 tab.

  11. Effect of chlorate, molybdate, and shikimic acid on Salmonella Typhimurium in aerobic and anaerobic cultures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two studies were conducted to examine the effects of shikimic acid (60 µg/mL) and(or) molybdate (1 mM) on the sensitivity of Salmonella enterica serovar Typhimurium to sodium chlorate (5 mM) during anaerobic (90% N2:5% CO2:5% H2) or aerobic growth in brain heart infusion broth supplemented with 5 mM...

  12. Direct ROS scavenging activity of CueP from Salmonella enterica serovar Typhimurium.

    PubMed

    Yoon, Bo-Young; Yeom, Ji-Hyun; Kim, Jin-Sik; Um, Si-Hyeon; Jo, Inseong; Lee, Kangseok; Kim, Yong-Hak; Ha, Nam-Chul

    2014-02-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is an intracellular pathogen that has evolved to survive in the phagosome of macrophages. The periplasmic copper-binding protein CueP was initially known to confer copper resistance to S. Typhimurium. Crystal structure and biochemical studies on CueP revealed a putative copper binding site surrounded by the conserved cysteine and histidine residues. A recent study reported that CueP supplies copper ions to periplasmic Cu, Zn-superoxide dismutase (SodCII) at a low copper concentration and thus enables the sustained SodCII activity in the periplasm. In this study, we investigated the role of CueP in copper resistance at a high copper concentration. We observed that the survival of a cueP-deleted strain of Salmonella in macrophage phagosome was significantly reduced. Subsequent biochemical experiments revealed that CueP specifically mediates the reduction of copper ion using electrons released during the formation of the disulfide bond. We observed that the copper ion-mediated Fenton reaction in the presence of hydrogen peroxide was blocked by CueP. This study provides insight into how CueP confers copper resistance to S. Typhimurium in copper-rich environments such as the phagosome of macrophages. PMID:24598994

  13. Salmonella enterica Serovar Typhimurium Invades Fibroblasts by Multiple Routes Differing from the Entry into Epithelial Cells▿

    PubMed Central

    Aiastui, Ana; Pucciarelli, M. Graciela; García-del Portillo, Francisco

    2010-01-01

    Fibroblasts are ubiquitous cells essential to tissue homeostasis. Despite their nonphagocytic nature, fibroblasts restrain replication of intracellular bacterial pathogens such as Salmonella enterica serovar Typhimurium. The extent to which the entry route of the pathogen determines this intracellular response is unknown. Here, we analyzed S. Typhimurium invasion in fibroblasts obtained from diverse origins, including primary cultures and stable nontransformed cell lines derived from normal tissues. Features distinct to the invasion of epithelial cells were found in all fibroblasts tested. In some fibroblasts, bacteria lacking the type III secretion system encoded in the Salmonella pathogenicity island 1 displayed significant invasion rates and induced the formation of lamellipodia and filopodia at the fibroblast-bacteria contact site. Other bacterial invasion traits observed in fibroblasts were the requirement of phosphatidylinositol 3-kinase, mitogen-activated protein kinase MEK1, and both actin filaments and microtubules. RNA interference studies showed that different Rho family GTPases are targeted by S. Typhimurium to enter into distinct fibroblasts. Rac1 and Cdc42 knockdown affected invasion of normal rat kidney fibroblasts, whereas none of the GTPases tested (Rac1, Cdc42, RhoA, or RhoG) was essential for invasion of immortalized human foreskin fibroblasts. Collectively, these data reveal a marked diversity in the modes used by S. Typhimurium to enter into fibroblasts. PMID:20368348

  14. Expression divergence between Escherichia coli and Salmonella enterica serovar Typhimurium reflects their lifestyles.

    PubMed

    Meysman, Pieter; Sánchez-Rodríguez, Aminael; Fu, Qiang; Marchal, Kathleen; Engelen, Kristof

    2013-06-01

    Escherichia coli K12 is a commensal bacteria and one of the best-studied model organisms. Salmonella enterica serovar Typhimurium, on the other hand, is a facultative intracellular pathogen. These two prokaryotic species can be considered related phylogenetically, and they share a large amount of their genetic material, which is commonly termed the "core genome." Despite their shared core genome, both species display very different lifestyles, and it is unclear to what extent the core genome, apart from the species-specific genes, plays a role in this lifestyle divergence. In this study, we focus on the differences in expression domains for the orthologous genes in E. coli and S. Typhimurium. The iterative comparison of coexpression methodology was used on large expression compendia of both species to uncover the conservation and divergence of gene expression. We found that gene expression conservation occurs mostly independently from amino acid similarity. According to our estimates, at least more than one quarter of the orthologous genes has a different expression domain in E. coli than in S. Typhimurium. Genes involved with key cellular processes are most likely to have conserved their expression domains, whereas genes showing diverged expression are associated with metabolic processes that, although present in both species, are regulated differently. The expression domains of the shared "core" genome of E. coli and S. Typhimurium, consisting of highly conserved orthologs, have been tuned to help accommodate the differences in lifestyle and the pathogenic potential of Salmonella. PMID:23427276

  15. Rapid detection of Salmonella typhimurium on fresh spinach leaves using phage-immobilized magnetoelastic biosensors

    NASA Astrophysics Data System (ADS)

    Horikawa, Shin; Li, Suiqiong; Chai, Yating; Park, Mi-Kyung; Shen, Wen; Barbaree, James M.; Vodyanoy, Vitaly J.; Chin, Bryan A.

    2011-06-01

    This paper presents an investigation into the use of magnetoelastic biosensors for the rapid detection of Salmonella typhimurium on fresh spinach leaves. The biosensors used in this investigation were comprised of a strip-shaped, goldcoated sensor platform (2 mm-long) diced from a ferromagnetic, amorphous alloy and a filamentous fd-tet phage which specifically binds with S. typhimurium. After surface blocking with bovine serum albumin, these biosensors were, without any preceding sample preparation, directly placed on wet spinach leaves inoculated with various concentrations of S. typhimurium. Upon contact with cells, the phage binds S. typhimurium to the sensor thereby increasing the total mass of the sensor. This change in mass causes a corresponding decrease in the sensor's resonant frequency. After 25 min, the sensors were collected from the leaf surface and measurements of the resonant frequency were performed immediately. The total assay time was less than 30 min. The frequency changes for measurement sensors (i.e., phageimmobilized) were found to be statistically different from those for control sensors (sensors without phage), down to 5 × 106 cells/ml. The detection limit may be improved by using smaller, micron-sized sensors that will have a higher probability of contacting Salmonella on the rough surfaces of spinach leaves.

  16. Identification of diminished tissue culture invasiveness among multiple antibiotic resistant Salmonella typhimurium DT104.

    PubMed

    Carlson, S A; Browning, M; Ferris, K E; Jones, B D

    2000-01-01

    Salmonella infections continue to cause gastrointestinal and systemic disease throughout the world. Salmonella typhimurium further poses a major health concern due to its apparent enhanced ability to acquire multiple antibiotic resistance genes. Currently it is unclear if multiresistant S. typhimurium are more or less pathogenic than non-resistant counterparts. Using an in vitro invasion assay, we evaluated the relative pathogenicity of over 400 multiresistant S. typhimurium isolates. Our studies failed to identify any isolates. However, we identified 12 isolates exhibiting invasive phenotypes that were constrained relative to controls. These strains were found in a variety of phagetypes all possessing at least a hexaresistant profile. Further studies revealed that the alterations in invasion were not due to changes in adherence. Limited studies exploring in vivo virulence revealed a mildly decreased ability to cause murine lethality for the hypoinvasive strain examined. These results indicate that the ability to cause disease is not increased but is rather mildly attenuated for certain isolates of multiresistant S. typhimurium. PMID:10623562

  17. Characterization of blaCMY plasmids and their possible role in source attribution of salmonella enterica serotype typhimurium infections

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella is an important cause of foodborne illness; however, identifying the source of these infections can be difficult. This is especially true for Salmonella serotype Typhimurium, which is found in diverse agricultural niches. Cephalosporins are one of the primary treatment choices for complic...

  18. Postmortem photonic imaging of lux-modified Salmonella typhimurium within the gastrointestinal tract of swine following oral inoculation in vivo

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study objective was to monitor Salmonella progression by photonic detection through segments of the gastrointestinal tract following oral inoculation. Pigs (~ 80 kg) were inoculated orally with 3.1 or 4.1×10*10 colony forming units (cfu) of Salmonella typhimurium transformed with plasmid pAK1-lu...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  20. Tetracycline accelerates the temporally-regulated invasion response in specific isolates of multidrug-resistant Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background Multidrug-resistant (MDR) Salmonella is associated with increased morbidity compared to antibiotic-sensitive strains and is an important health and safety concern in both humans and animals. Salmonella enterica serovar Typhimurium is a prevalent cause of foodborne disease, and a consider...

  1. PREDICTIVE MODEL FOR SURVIVAL AND GROWTH OF SALMONELLA TYPHIMURIUM DT104 ON CHICKEN SKIN DURING TEMPERATURE ABUSE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To better predict risk of Salmonella infection from chicken subjected to temperature abuse, a study was undertaken to develop a predictive model for survival and growth of Salmonella Typhimurium DT104 on chicken skin with native micro flora. For model development, chicken skin portions were inocula...

  2. Analysis of antimicrobial resistance genes detected in multidrug-resistant salmonella enterica serovar typhimurium isolated from food animals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of multi drug resistance (MDR) in foodborne pathogens such as Salmonella enterica is a concern for both animal and human health. MDR Salmonella enterica serovar Typhimurium is the most prevalent penta-resistant serovar isolated from animals as part of the National Antimicrobial Resis...

  3. Correlating Blood Immune Parameters and a CCT7 Genetic Variant with the Shedding of Salmonella enterica Serovar Typhimurium in Swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the current study, 40 crossbred pigs were intranasally inoculated with Salmonella enterica serovar Typhimurium and monitored for Salmonella fecal shedding and blood immune parameters at 2, 7, 14 and 20 days post-inoculation (dpi). Using a multivariate permutation test, a positive correlation was...

  4. Cellular Requirements for Systemic Control of Salmonella enterica Serovar Typhimurium Infections in Mice

    PubMed Central

    Bedoui, Sammy

    2014-01-01

    The rational design of vaccines requires an understanding of the contributions of individual immune cell subsets to immunity. With this understanding, targeted vaccine delivery approaches and adjuvants can be developed to maximize vaccine efficiency and to minimize side effects (S. H. E. Kaufmann et al., Immunity 33:555–577, 2010; T. Ben-Yedidia and R. Arnon, Hum. Vaccines 1:95–101, 2005). We have addressed the contributions of different immune cell subsets and their ability to contribute to the control and clearance of the facultative intracellular pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) in a murine model. Using a systematic and reproducible model of experimental attenuated S. Typhimurium infection, we show that distinct lymphocyte deficiencies lead to one of four different infection outcomes: clearance, chronic infection, early death, or late death. Our study demonstrates a high level of functional redundancy in the ability of different lymphocyte subsets to provide interferon gamma (IFN-γ), a critical cytokine in Salmonella immunity. Whereas early control of the infection was entirely dependent on IFN-γ but not on any particular lymphocyte subset, clearance of the infection critically required CD4+ T cells but appeared to be independent of IFN-γ. These data reinforce the idea of a bimodal immune response against Salmonella: an early T cell-independent but IFN-γ-dependent phase and a late T cell-dependent phase that may be IFN-γ independent. PMID:25225248

  5. Cellular requirements for systemic control of Salmonella enterica serovar Typhimurium infections in mice.

    PubMed

    Kupz, Andreas; Bedoui, Sammy; Strugnell, Richard A

    2014-12-01

    The rational design of vaccines requires an understanding of the contributions of individual immune cell subsets to immunity. With this understanding, targeted vaccine delivery approaches and adjuvants can be developed to maximize vaccine efficiency and to minimize side effects (S. H. E. Kaufmann et al., Immunity 33:555-577, 2010; T. Ben-Yedidia and R. Arnon, Hum. Vaccines 1:95-101, 2005). We have addressed the contributions of different immune cell subsets and their ability to contribute to the control and clearance of the facultative intracellular pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) in a murine model. Using a systematic and reproducible model of experimental attenuated S. Typhimurium infection, we show that distinct lymphocyte deficiencies lead to one of four different infection outcomes: clearance, chronic infection, early death, or late death. Our study demonstrates a high level of functional redundancy in the ability of different lymphocyte subsets to provide interferon gamma (IFN-γ), a critical cytokine in Salmonella immunity. Whereas early control of the infection was entirely dependent on IFN-γ but not on any particular lymphocyte subset, clearance of the infection critically required CD4(+) T cells but appeared to be independent of IFN-γ. These data reinforce the idea of a bimodal immune response against Salmonella: an early T cell-independent but IFN-γ-dependent phase and a late T cell-dependent phase that may be IFN-γ independent. PMID:25225248

  6. Growth potential of exponential- and stationary-phase Salmonella Typhimurium during sausage fermentation.

    PubMed

    Birk, T; Henriksen, S; Müller, K; Hansen, T B; Aabo, S

    2016-11-01

    Raw meat for sausage production can be contaminated with Salmonella. For technical reasons, meat is often frozen prior to mincing but it is unknown how growth of Salmonella in meat prior to freezing affects its growth potential during sausage fermentation. We investigated survival of exponential- and stationary-phase Salmonella Typhimurium (DT12 and DTU292) during freezing at -18°C and their subsequent growth potential during 72h sausage fermentation at 25°C. After 0, 7 and >35d of frozen storage, sausage batters were prepared with NaCl (3%) and NaNO2 (0, 100ppm) and fermented with and without starter culture. With no starter culture, both strains grew in both growth phases. In general, a functional starter culture abolished S. Typhimurium growth independent of growth phase and we concluded that ensuring correct fermentation is important for sausage safety. However, despite efficient fermentation, sporadic growth of exponential-phase cells of S. Typhimurium was observed drawing attention to the handling and storage of sausage meat. PMID:27423056

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  8. A high affinity phage-displayed peptide as a recognition probe for the detection of Salmonella Typhimurium.

    PubMed

    Agrawal, Shailaja; Kulabhusan, Prabir Kumar; Joshi, Manali; Bodas, Dhananjay; Paknikar, Kishore M

    2016-08-10

    Salmonellosis is one of the most common and widely distributed foodborne diseases. A sensitive and robust detection method of Salmonella Typhimurium (S. Typhimurium) in food can critically prevent a disease outbreak. In this work, the use of phage displayed peptides was explored for the detection of S. Typhimurium. A phage-displayed random dodecapeptide library was subjected to biopanning against lipopolysaccharide (LPS) of S. Typhimurium. The peptide NFMESLPRLGMH (pep49) derived from biopanning displayed a high affinity (25.8nM) for the LPS of S. Typhimurium and low cross-reactivity with other strains of Salmonella and related Gram-negative bacteria. Molecular insights into the interaction of pep49 with the LPS of S. Typhimurium was gleaned using atomistic molecular dynamics simulations and docking. It was deduced that the specificity of pep49 with S. Typhimurium LPS originated from the interactions of pep49 with abequose that is found only in the O-antigen of S. Typhimurium. Further, pep49 was able to detect S. Typhimurium at a LOD of 10(3) CFU/mL using ELISA, and may be a potential cost efficient alternative to antibodies. PMID:27220907

  9. 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

  10. A new wireless detection device for the in-situ identification of Salmonella Typhimurium

    NASA Astrophysics Data System (ADS)

    Chai, Yating; Wikle, Howard C.; Park, Mi-kyung; Horikawa, Shin; Hong, Xie; Chin, Bryan A.

    2013-05-01

    This paper presents a new device and method for the in-situ detection of Salmonella Typhimurium on tomato surfaces. This real-time in-situ detection was accomplished with phage-based magnetoelastic (ME) biosensors on fresh food surfaces. The E2 phage from a landscape phage library serves as the bio-recognition element that has the capability of binding specifically with S. Typhimurium. This mass-sensitive ME biosensor is wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field. When the biosensor binds with S. Typhimurium, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency. Until now, ME sensors had to be collected from the tomato surface where they are exposed to S. Typhimurium and inserted into a measurement coil for the detection of the bacterium. In contrast, the newly designed test device allows the whole detection process to take place directly on the tomato. Changes in resonant frequency over time due to the accumulation of S. Typhimurium on the sensor were measured and are presented. Real-time in-situ detection of 20 minutes was achieved. In addition, this new methodology effectively decreases the measurement error and enables the simultaneous detection of multiple pathogens.

  11. Interleukin-17A is required to suppress invasion of Salmonella enterica serovar Typhimurium to enteric mucosa

    PubMed Central

    Mayuzumi, Hirokazu; Inagaki-Ohara, Kyoko; Uyttenhove, Catherine; Okamoto, Yuko; Matsuzaki, Goro

    2010-01-01

    Salmonella enterica serovar Typhimurium (S. typhimurium) causes a localized enteric infection and its elimination is dependent on a T helper type 1 immune response. However, the mechanism of the protective immune response against the pathogen in gut-associated lymphoid tissue (GALT) at an early stage of the infection is not yet clarified. Here, we show that interleukin-17A (IL-17A) was constitutively expressed in GALT; it was also detected on crypt and epithelial cells of the small intestine. Neutralization of the IL-17A in the intestinal lumen exacerbated epithelial damage induced by intestinal S. typhimurium infection at an early stage of the infection. The result suggests that IL-17A has a pivotal role in the immediate early stage of protection against bacterial infection at the intestinal mucosa. As IL-17A neutralization also suppressed the constitutive localization of β-defensin 3 (BD3), an IL-17A-induced antimicrobial peptide, at the apical site of the intestinal mucosa, it is estimated that IL-17A constitutively induces the expression of the antimicrobial peptide to kill invading pathogens at the epithelial surface immediately after the infection. In contrast, interferon-γ is induced around 3 days after S. typhimurium infection, and its expression level increases thereafter. Taken together, the findings lead to the hypothesis that IL-17A participates in the immediate early stage of protection against S. typhimurium intestinal infection whereas interferon-γ is important at a later stage of the infection. PMID:20575990

  12. Multiple roles of putrescine and spermidine in stress resistance and virulence of Salmonella enterica serovar Typhimurium.

    PubMed

    Espinel, Irene Cartas; Guerra, Priscila Regina; Jelsbak, Lotte

    2016-06-01

    Polyamines (putrescine and spermidine) are small-cationic amines ubiquitous in nature and present in most living cells. In recent years they have been linked to virulence of several human pathogens including Shigella spp and Salmonella enterica serovar Typhimurium (S. Typhimurium). Central to S. Typhimurium virulence is the ability to survive and replicate inside macrophages and resisting the antimicrobial attacks in the form of oxidative and nitrosative stress elicited from these cells. In the present study, we have investigated the role of polyamines in intracellular survival and systemic infections of mice. Using a S. Typhimurium mutant defective for putrescine and spermidine biosynthesis, we show that polyamines are essential for coping with reactive nitrogen species, possibly linking polyamines to increased intracellular stress resistance. However, using a mouse model defective for nitric oxide production, we find that polyamines are required for systemic infections independently of host-produced reactive nitrogen species. To distinguish between the physiological roles of putrescine and spermidine, we constructed a strain deficient for spermidine biosynthesis and uptake, but with retained ability to produce and import putrescine. Interestingly, in this mutant we observe a strong attenuation of virulence during infection of mice proficient and deficient for nitric oxide production suggesting that spermidine, specifically, is essential for virulence of S. Typhimurium. PMID:27041598

  13. Salmonella enterica serovar Typhimurium lacking hfq gene confers protective immunity against murine typhoid.

    PubMed

    Allam, Uday Shankar; Krishna, M Gopala; Lahiri, Amit; Joy, Omana; Chakravortty, Dipshikha

    2011-01-01

    Salmonella enterica is an important enteric pathogen and its various serovars are involved in causing both systemic and intestinal diseases in humans and domestic animals. The emergence of multidrug-resistant strains of Salmonella leading to increased morbidity and mortality has further complicated its management. Live attenuated vaccines have been proven superior over killed or subunit vaccines due to their ability to induce protective immunity. Of the various strategies used for the generation of live attenuated vaccine strains, focus has gradually shifted towards manipulation of virulence regulator genes. Hfq is a RNA chaperon which mediates the binding of small RNAs to the mRNA and assists in post-transcriptional gene regulation in bacteria. In this study, we evaluated the efficacy of the Salmonella Typhimurium Δhfq strain as a candidate for live oral vaccine in murine model of typhoid fever. Salmonella hfq deletion mutant is highly attenuated in cell culture and animal model implying a significant role of Hfq in bacterial virulence. Oral immunization with the Salmonella hfq deletion mutant efficiently protects mice against subsequent oral challenge with virulent strain of Salmonella Typhimurium. Moreover, protection was induced upon both multiple as well as single dose of immunizations. The vaccine strain appears to be safe for use in pregnant mice and the protection is mediated by the increase in the number of CD4(+) T lymphocytes upon vaccination. The levels of serum IgG and secretory-IgA in intestinal washes specific to lipopolysaccharide and outer membrane protein were significantly increased upon vaccination. Furthermore, hfq deletion mutant showed enhanced antigen presentation by dendritic cells compared to the wild type strain. Taken together, the studies in murine immunization model suggest that the Salmonella hfq deletion mutant can be a novel live oral vaccine candidate. PMID:21347426

  14. Effect of streptomycin administration on colonization resistance to Salmonella typhimurium in mice.

    PubMed Central

    Que, J U; Hentges, D J

    1985-01-01

    The addition of 5 mg of streptomycin sulfate per ml to the drinking water of Swiss white mice resulted in a 100,000-fold reduction in the 50% implantation dose of streptomycin-resistant Salmonella typhimurium for the animals. When streptomycin-treated and untreated mice were challenged orogastrically with 10(3) viable S. typhimurium organisms, 100% of the treated and none of the untreated mice excreted the pathogen in their feces. Similarly, translocation of S. typhimurium from the intestinal tract to the liver, spleen, and mesentery occurred in 10 of 10 treated mice but in none of the untreated mice 7 days after challenge with 10(3) CFU. Studies of colonization dynamics showed that S. typhimurium was present at high population levels in the intestines of streptomycin-treated mice and in detectable levels in the liver, spleen, and mesentery within 72 h after challenge with 10(3), 10(5), or 10(8) organisms. In untreated mice challenged with either 10(3) or 10(5) S. typhimurium organisms, the organisms were isolated from ileal and cecal tissues but not from ileal or cecal contents or from extraintestinal tissue 72 h after challenge. When untreated mice were challenged with 10(8) organisms, however, S. typhimurium was present in all organs and in intestinal contents. Streptomycin treatment, therefore, facilitated colonization and development of streptomycin-resistant S. typhimurium populations in intestines of mice and the subsequent translocation of the organisms from the intestinal tract to other tissues. PMID:3884509

  15. 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. PMID:27154729

  16. The role of the st313-td gene in virulence of Salmonella Typhimurium ST313.

    PubMed

    Herrero-Fresno, Ana; Wallrodt, Inke; Leekitcharoenphon, Pimlapas; Olsen, John Elmerdahl; Aarestrup, Frank M; Hendriksen, Rene S

    2014-01-01

    Multidrug-resistant Salmonella enterica serovar Typhimurium ST313 has emerged in sub-Saharan Africa causing severe infections in humans. Therefore, it has been speculated that this specific sequence type, ST313, carries factors associated with increased pathogenicity. We assessed the role in virulence of a gene with a yet unknown function, st313-td, detected in ST313 through comparative genomics. Additionally, the structure of the genomic island ST313-GI, harbouring the gene was determined. The gene st313-td was cloned into wild type S. Typhimurium 4/74 (4/74-C) as well as knocked out in S. Typhimurium ST313 02-03/002 (Δst313-td) followed by complementation (02-03/002-C). Δst313-td was less virulent in mice following i.p. challenge than the wild type and this phenotype could be partly complemented in trans, indicating that st313-td plays a role during systemic infection. The gene st313-td was shown not to affect invasion of cultured epithelial cells, while the absence of the gene significantly affects uptake and intracellular survival within macrophages. The gene st313-td was proven to be strongly associated to invasiveness, harboured by 92.5% of S. Typhimurium blood isolates (n = 82) and 100% of S. Dublin strains (n = 50) analysed. On the contrary, S. Typhimurium isolates of animal and food origin (n = 82) did not carry st313-td. Six human, non-blood isolates of S. Typhimurium from Belarus, China and Nepal harboured the gene and belonged to sequence types ST398 and ST19. Our data showed a global presence of the st313-td gene and in other sequence types than ST313. The gene st313-td was shown to be expressed during logarithmic phase of growth in 14 selected Salmonella strains carrying the gene. This study reveals that st313-td plays a role in S. Typhimurium ST313 pathogenesis and adds another chapter to understanding of the virulence of S. Typhimurium and in particular of the emerging sequence type ST313. PMID:24404174

  17. The Role of the st313-td Gene in Virulence of Salmonella Typhimurium ST313

    PubMed Central

    Herrero-Fresno, Ana; Wallrodt, Inke; Leekitcharoenphon, Pimlapas; Olsen, John Elmerdahl; Aarestrup, Frank M.; Hendriksen, Rene S.

    2014-01-01

    Multidrug-resistant Salmonella enterica serovar Typhimurium ST313 has emerged in sub-Saharan Africa causing severe infections in humans. Therefore, it has been speculated that this specific sequence type, ST313, carries factors associated with increased pathogenicity. We assessed the role in virulence of a gene with a yet unknown function, st313-td, detected in ST313 through comparative genomics. Additionally, the structure of the genomic island ST313-GI, harbouring the gene was determined. The gene st313-td was cloned into wild type S. Typhimurium 4/74 (4/74-C) as well as knocked out in S. Typhimurium ST313 02–03/002 (Δst313-td) followed by complementation (02-03/002-C). Δst313-td was less virulent in mice following i.p. challenge than the wild type and this phenotype could be partly complemented in trans, indicating that st313-td plays a role during systemic infection. The gene st313-td was shown not to affect invasion of cultured epithelial cells, while the absence of the gene significantly affects uptake and intracellular survival within macrophages. The gene st313-td was proven to be strongly associated to invasiveness, harboured by 92.5% of S. Typhimurium blood isolates (n = 82) and 100% of S. Dublin strains (n = 50) analysed. On the contrary, S. Typhimurium isolates of animal and food origin (n = 82) did not carry st313-td. Six human, non-blood isolates of S. Typhimurium from Belarus, China and Nepal harboured the gene and belonged to sequence types ST398 and ST19. Our data showed a global presence of the st313-td gene and in other sequence types than ST313. The gene st313-td was shown to be expressed during logarithmic phase of growth in 14 selected Salmonella strains carrying the gene. This study reveals that st313-td plays a role in S. Typhimurium ST313 pathogenesis and adds another chapter to understanding of the virulence of S. Typhimurium and in particular of the emerging sequence type ST313. PMID:24404174

  18. [Molecular characterization of Salmonella enterica serovar Typhimurium strains isolated from humans in Turkey].

    PubMed

    Dolapçı, İştar; Tekeli, Alper; Şahin, Fikret; Erdem, Birsel

    2015-10-01

    Multidrug resistant (MDR) Salmonella infections, especially infections due to Salmonella Typhimurium DT104 phage type strains are an important public health issue in many parts of the world. S.Typhimurium is the most common serotype isolated from clinical samples in Turkey but we have limited data about the phage types of these isolates. The aims of this study were to find out whether these MDR S.Typhimurium isolates are DT104 phage type isolates and have class 1 integrons and to investigate the relationships of these characteristics between plasmid and pulsed field gel electrophoresis (PFGE) profiles. A total of 66 S.Typhimurium stock strains selected from Enterobacteria Laboratory culture collections of Ankara University School of Medicine, Department of Medical Microbiology were investigated by plasmid profile analysis (PPA) and PFGE with the use of XbaI and SpeI enzymes. The presence of class 1 integrons and the phage type 104 were investigated by polymerase chain reaction (PCR). The strains used in the study were sporadically isolated cases from seven provinces after year 2000 with ACSSuT (63), ACGSSuTT/S (1), ACSSuTT/S (1) and ASSuTT/S (1) resistance types [ampicillin (A), chloramphenicol (C), gentamicin (G), streptomycin (S), sulphonamide (Su), tetracycline (T), trimethoprim/sulfamethoxazole (T/S)]. Of the isolates 65 were found as DT104 phage type. Forty-three S.Typhimurium DT104 isolates that carry class 1 integrons had five different bands between 350-1600 base pairs (bp); all of the isolates harbored 1-4 plasmids with sizes ranging from 1.0-180 kbp and 62 isolates had 90 kbp plasmid which was serotype specific and virulence related. S.Typhimurium DT104 isolates were grouped into five (X1-X5) and seven (S1-S7) profiles with XbaI and SpeI enzymes, respectively. When the profiles of the two enzymes were evaluated, 58 of the 65 (89.2%) isolates showed similar (X1.S1) profile. The molecular characteristics of the most S.Typhimurium isolates were clustered in

  19. Analysis of the ArcA regulon in anaerobically grown Salmonella enterica sv. Typhimurium

    PubMed Central

    2011-01-01

    Background Salmonella enterica serovar Typhimurium (S. Typhimurium) is a Gram-negative pathogen that must successfully adapt to the broad fluctuations in the concentration of dissolved dioxygen encountered in the host. In Escherichia coli, ArcA (Aerobic Respiratory Control) helps the cells to sense and respond to the presence of dioxygen. The global role of ArcA in E. coli is well characterized; however, little is known about its role in anaerobically grown S. Typhimurium. Results We compared the transcriptional profiles of the virulent wild-type (WT) strain (ATCC 14028s) and its isogenic arcA mutant grown under anaerobic conditions. We found that ArcA directly or indirectly regulates 392 genes (8.5% of the genome); of these, 138 genes are poorly characterized. Regulation by ArcA in S. Typhimurium is similar, but distinct from that in E. coli. Thus, genes/operons involved in core metabolic pathways (e.g., succinyl-CoA, fatty acid degradation, cytochrome oxidase complexes, flagellar biosynthesis, motility, and chemotaxis) were regulated similarly in the two organisms. However, genes/operons present in both organisms, but regulated differently by ArcA in S. Typhimurium included those coding for ethanolamine utilization, lactate transport and metabolism, and succinate dehydrogenases. Salmonella-specific genes/operons regulated by ArcA included those required for propanediol utilization, flagellar genes (mcpAC, cheV), Gifsy-1 prophage genes, and three SPI-3 genes (mgtBC, slsA, STM3784). In agreement with our microarray data, the arcA mutant was non-motile, lacked flagella, and was as virulent in mice as the WT. Additionally, we identified a set of 120 genes whose regulation was shared with the anaerobic redox regulator, Fnr. Conclusion(s) We have identified the ArcA regulon in anaerobically grown S. Typhimurium. Our results demonstrated that in S. Typhimurium, ArcA serves as a transcriptional regulator coordinating cellular metabolism, flagella biosynthesis, and

  20. Reduction in faecal excretion of Salmonella typhimurium strain F98 in chickens vaccinated with live and killed S. typhimurium organisms.

    PubMed Central

    Barrow, P. A.; Hassan, J. O.; Berchieri, A.

    1990-01-01

    Chickens given orally at 4 days of age a smooth spectinomycin resistant mutant (Spcr) of Salmonella typhimurium strain F98 excreted the organism in their faeces for approximately 4 weeks. Following oral administration of a nalidixic acid resistant (Nalr) mutant of the same strain 4 weeks later when the chickens had virtually cleared themselves of the first infection, these chickens excreted far fewer salmonella organisms and for a shorter time than did a previously uninfected control group of chickens which were infected at the same time with the Nalr mutant. Chickens inoculated intramuscularly at 4 days developed a similar immunity to challenge and also excreted the immunizing strain in their faeces. In contrast intramuscular inoculation or incorporation into the food of formalin-killed S. typhimurium organisms had little lasting effect on the faecal excretion of the challenge strain. Two attenuated mutants of strain F98 Nalr were produced: one was a rough strain produced by lytic bacteriophage and the other was an aro A auxotrophic mutant which had been cured of the 85 kilobase-pair virulence-associated plasmid. These mutants were avirulent for chickens, mice, calves and man and when ingested by human volunteers did not persist in the faeces. When inoculated intramuscularly into chickens they produced an early reduction in faecal excretion of the challenge strain (Spcr) which was not maintained. Oral administration of both strains produced reductions in faecal excretion of the challenge strain. This was much more noticeable with the rough strain which was itself excreted for a much longer period than the parent strain. PMID:2189743

  1. Survival of Salmonella Typhimurium in poultry-based meat preparations during grilling, frying and baking.

    PubMed

    Roccato, Anna; Uyttendaele, Mieke; Cibin, Veronica; Barrucci, Federica; Cappa, Veronica; Zavagnin, Paola; Longo, Alessandra; Ricci, Antonia

    2015-03-16

    The burden of food-borne diseases still represents a threat to public health; in 2012, the domestic setting accounted for 57.6% of strong-evidence EU food-borne Salmonella outbreaks. Next to cross-contamination, inadequate cooking procedure is considered as one of the most important factors contributing to food-borne illness. The few studies which have assessed the effect of domestic cooking on the presence and numbers of pathogens in different types of meat have shown that consumer-style cooking methods can allow bacteria to survive and that the probability of eating home-cooked poultry meat that still contains surviving bacteria after heating is higher than previously assumed. Thus, the main purpose of this study was to reproduce and assess the effect of several types of cooking treatments (according to label instructions and not following label instructions) on the presence and numbers of Salmonella Typhimurium DT 104 artificially inoculated in five types of poultry-based meat preparations (burgers, sausages, ready-to-cook-kebabs, quail roulades and extruded roulades) that are likely to be contaminated by Salmonella. Three contamination levels (10 cfu/g; 100 cfu/g and 1000 cfu/g) and three cooking techniques (grilling, frying and baking) were applied. Cooking treatments performed according to label instructions eliminated Salmonella Typhimurium (absence per 25g) for contamination levels of 10 and 100 cfu/g but not for contamination levels of 1000 cfu/g. After improper cooking, 26 out of 78 samples were Salmonella-positive, and 23 out of these 26 samples were artificially contaminated with bacterial loads between 100 and 1000 cfu/g. Nine out of 26 samples provided quantifiable results with a minimum level of 1.4MPN/g in kebabs (initial inoculum level: 100 cfu/g) after grilling and a maximum level of 170MPN/g recorded in sausages (initial inoculum level: 1000 cfu/g) after grilling. Kebabs were the most common Salmonella-positive meat product after cooking

  2. Multidrug resistance in Salmonella enterica serotype Typhimurium from humans in France (1993 to 2003).

    PubMed

    Weill, François-Xavier; Guesnier, Françoise; Guibert, Véronique; Timinouni, Mohammed; Demartin, Marie; Polomack, Lucette; Grimont, Patrick A D

    2006-03-01

    The aim of this study was to determine the distribution of the antimicrobial resistance phenotypes (R types), the phage types and XbaI-pulsed-field gel electrophoresis (PFGE) types, the genes coding for resistance to beta-lactams and to quinolones, and the class 1 integrons among a representative sample of Salmonella enterica serotype Typhimurium isolates collected from humans in 2002 through the French National Reference Center for Salmonella (NRC-Salm) network. The trends in the evolution of antimicrobial resistance of serotype Typhimurium were reviewed by using NRC-Salm data from 1993, 1997, 2000, and 2003. In 2002, 3,998 isolates of serotype Typhimurium were registered at the NRC-Salm among 11,775 serotyped S. enterica isolates (34%). The most common multiple antibiotic resistance pattern was resistance to amoxicillin, chloramphenicol, streptomycin and spectinomycin, sulfonamides, and tetracycline (ACSSpSuTe R type), with 156 isolates (48.8%). One isolate resistant to extended-spectrum cephalosporins due to the production of TEM-52 extended-spectrum beta-lactamase was detected (0.3%), and one multidrug-resistant isolate was highly resistant to ciprofloxacin (MIC > 32 mg/liter). We found that 57.2% of the isolates tested belonged to the DT104 clone. The main resistance pattern of DT104 isolates was R type ACSSpSuTe (83.2%). However, evolutionary changes have occurred within DT104, involving both loss (variants of Salmonella genomic island 1) and acquisition of genes for drug resistance to trimethoprim or to quinolones. PFGE profile X1 was the most prevalent (74.5%) among DT104 isolates, indicating the need to use a more discriminatory subtyping method for such isolates. Global data from the NRC-Salm suggested that DT104 was the main cause of multidrug resistance in serotype Typhimurium from humans from at least 1997 to 2003, with a roughly stable prevalence during this period. PMID:16517842

  3. Natural surface coating to inactivate Salmonella enterica serovar Typhimurium and maintain quality of cherry tomatoes.

    PubMed

    Yun, Juan; Fan, Xuetong; Li, Xihong; Jin, Tony Z; Jia, Xiaoyu; Mattheis, James P

    2015-01-16

    The objective of the present study was to investigate the effectiveness of zein-based coatings in reducing populations of Salmonella enterica serovar Typhimurium and preserving quality of cherry tomatoes. Tomatoes were inoculated with a cocktail of S. Typhimurium LT2 plus three attenuated strains on the smooth skin surface and stem scar area. The zein-based coatings with and without cinnamon (up to 20%) and mustard essential oil or a commercial wax formulation were applied onto tomatoes and the treated fruits were stored at 10 °C for up to 3 weeks. Populations of S. Typhimurium decreased with increased essential oil concentration and storage duration. S. Typhimurium populations on the smooth skin surface were reduced by 4.6 and 2.8 log colony forming units(CFU)/g by the zein coatings with 20% cinnamon and 20% mustard oil, respectively, 5h after coating. The same coating reduced populations of S. Typhimurium to levels below detection limit (1.0 log CFU/g) on the stem scar area of tomato during 7 days of storage at 10 °C. Salmonella populations were not reduced on fruit coated with the commercial wax. All of the coatings resulted in reduced weight loss compared with uncoated control. Compared with the control, loss of firmness and ascorbic acid during storage was prevented by all of the coatings except the zein coating with 20% mustard oil which enhanced softening. Color was not consistently affected by any of the coating treatments during 21 days of storage at 10°C. The results suggest that the zein-based coating containing cinnamon oil might be used to enhance microbial safety and quality of tomato. PMID:25462924

  4. Growth kinetics response of a Salmonella typhimurium poultry marker strain to fresh produce extracts.

    PubMed

    Nutt, J D; Li, X; Woodward, C L; Zabala-Díaz, I B; Ricke, S C

    2003-09-01

    The purpose of this research was to assess growth response of a Salmonella typhimurium poultry marker strain to fresh homogenized vegetables. Salmonella growth rates were significantly higher (p<0.05) in jalapeno extracts than any other produce extract examined. Growth rates on samples of broccoli and lettuce extracts were greater (p<0.05) than the respective growth rates on bell pepper and tomato. Broccoli extracts yielded the highest extent of growth (4 h optical density) followed by jalapeno and bell pepper extracts. From this study, it appears that fresh produce extracts have different abilities to significantly alter growth response in Salmonella. This could potentially be explained by the variations of pH, nutrient availability to the bacteria, or unknown components found within fresh produce. PMID:12798123

  5. Chloramphenicol and tetracycline decrease motility and increase invasion and attachment gene expression in specific isolates of multidrug-resistant Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is one of the most common serovars isolated from humans and livestock, and over 35 percent of these isolates are resistant to three or more antibiotics. Multidrug-resistant (MDR) Salmonella is a public health concern as it is associated with i...

  6. Changes in Expression of Virulence Mechanisms in Three Related Salmonella Typhimurium Mutants with Increasing Multi-Drug Resistance Properties, as Determined by Microarray Analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella Typhimurium is a common cause of Salmonellosis and has been associated with multi-drug resistance. Previously, the wild-type strain (Salmonella Typhimurium ATCC 14028) was exposed to increasing concentrations of nalidixic acid to derive naturally occurring drug resistant isolates. Three d...

  7. Iron regulated genes of Salmonella enterica serovar Typhimurium in response to norepinephrine and the requirement of fepCDG for norepinephrine-enhanced growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of catecholamines in vivo may stimulate enteric bacteria including the foodborne pathogen Salmonella enterica serovar Typhimurium by two mechanisms, acting as a quorum sensing signal and providing iron in the presence of serum. To identify genes of Salmonella Typhimurium that participa...

  8. Genetic Analysis of thr Mutations in Salmonella typhimurium

    PubMed Central

    Stuttard, Colin

    1973-01-01

    Previous workers divided threonine-requiring (Thr−) strains of Salmonella into three phenotypes with mutations in four complementation groups. The mutations were deemed to define four genes in the order thrD-C-A-B at minute zero on the Salmonella linkage map. In the present study 12 of these mutants were reexamined together with eight new Thr− strains. The three phenotypes were: homoserine-requiring (Hom−); Thr−, feeders of Hom− strains; Thr−, nonfeeders. Exact correlation between these phenotypic groups and three complementation groups was confirmed by abortive transduction. No evidence was found for intergenic complementation between mutations in Hom− strains. It is proposed that thr mutations define three genes rather than four and that these be renamed thrA (Hom−), thrB (Thr− feeders), and thrC (Thr− nonfeeders) to correspond with the sequence of reactions in threonine biosynthesis. Double mutant trpRthr strains were used in reciprocal three-point transduction tests to establish the order of thr mutation sites. Although revisions were made in the classification or location of several mutations, there was an overall correlation of complementation group, phenotype, and map position. The present data provide a basis for further correlation of threonine genes and biosynthetic enzymes, and analysis of cross regulation in aspartate amino acid biosynthesis in Salmonella. PMID:4583208

  9. Salmonella enterica serovars Typhimurium and Typhi as model organisms

    PubMed Central

    Garai, Preeti; Gnanadhas, Divya Prakash; Chakravortty, Dipshikha

    2012-01-01

    The lifestyle of intracellular pathogens has always questioned the skill of a microbiologist in the context of finding the permanent cure to the diseases caused by them. The best tool utilized by these pathogens is their ability to reside inside the host cell, which enables them to easily bypass the humoral immunity of the host, such as the complement system. They further escape from the intracellular immunity, such as lysosome and inflammasome, mostly by forming a protective vacuole-bound niche derived from the host itself. Some of the most dreadful diseases are caused by these vacuolar pathogens, for example, tuberculosis by Mycobacterium or typhoid fever by Salmonella. To deal with such successful pathogens therapeutically, the knowledge of a host-pathogen interaction system becomes primarily essential, which further depends on the use of a model system. A well characterized pathogen, namely Salmonella, suits the role of a model for this purpose, which can infect a wide array of hosts causing a variety of diseases. This review focuses on various such aspects of research on Salmonella which are useful for studying the pathogenesis of other intracellular pathogens. PMID:22722237

  10. Subunit-specific phenotypes of Salmonella typhimurium HU mutants.

    PubMed Central

    Hillyard, D R; Edlund, M; Hughes, K T; Marsh, M; Higgins, N P

    1990-01-01

    Salmonella hupA and hupB mutants were studied to determine the reasons for the high degree of conservation in HU structure in bacteria. We found one HU-1-specific effect; the F'128 plasmid was 25-fold less stable in hupB compared with hupA or wild-type cells. F' plasmids were 120-fold more unstable in hupA hupB double mutants compared with wild-type cells, and the double mutant also had a significant alteration in plasmid DNA structure. pBR322 DNA isolated from hupA hupB strains was deficient in supercoiling by 10 to 15% compared with wild-type cells, and the topoisomer distribution was significantly more heterogeneous than in wild-type or single-mutant strains. Other systems altered by HU inactivation included flagellar phase variation and phage Mu transposition. However, Mu transposition rates were only about fourfold lower in Salmonella HU double mutants. One reason that Salmonella HU double mutants may be less defective for Mu transposition than E. coli is the synthesis in double mutants of a new, small, basic heat-stable protein, which might partially compensate for the loss of HU. The results indicate that although either HU-1 or HU-2 subunit alone may accommodate the cellular need for general chromosomal organization, the selective pressure to conserve HU-1 and HU-2 structure during evolution could involve specialized roles of the individual subunits. Images PMID:2168381

  11. Sanitizing alternatives for Escherichia coli and Salmonella typhimurium on bell peppers at household kitchens.

    PubMed

    Soto Beltran, Marcela; Jimenez Edeza, Maribel; Viera, Celina; Martinez, Celida I; Chaidez, Cristobal

    2013-01-01

    Fresh fruits and vegetables are known to play an important role as carriers of disease-causing organisms in household kitchens. The aims of this study were to assess and compare the effectiveness of sodium hypochlorite, organic acid-based and silver-based products to reduce Escherichia coli and Salmonella typhimurium inoculated on individual bell pepper pieces. Inoculated bell pepper pieces (n = 5) were submerged in sodium hypochlorite, organic acid-based and silver-based product solutions, at the concentration specified in the product label for sanitization of fruits and vegetables. Sodium hypochlorite reduced E. coli and Salmonella typhimurium by 3.13 Log10/25 cm(2) and 2.73 Log10/25 cm(2), respectively. Organic-based and silver-based products reduced E. coli and S. typhimurium by 2.23 Log10/25 cm(2), 1.74 Log10/25 cm(2) and 2.10 Log10/25 cm(2), 1.92 Log10/25 cm(2), respectively. The results showed that greater attention is needed in selecting sanitizing products to kill or remove human pathogens from fresh produce to minimize risk of foodborne infections. PMID:23067329

  12. Propanediol utilization genes (pdu) of Salmonella typhimurium: three genes for the propanediol dehydratase.

    PubMed Central

    Bobik, T A; Xu, Y; Jeter, R M; Otto, K E; Roth, J R

    1997-01-01

    The propanediol utilization (pdu) operon of Salmonella typhimurium encodes proteins required for the catabolism of propanediol, including a coenzyme B12-dependent propanediol dehydratase. A clone that expresses propanediol dehydratase activity was isolated from a Salmonella genomic library. DNA sequence analysis showed that the clone included part of the pduF gene, the pduABCDE genes, and a long partial open reading frame (ORF1). The clone included 3.9 kbp of pdu DNA which had not been previously sequenced. Complementation and expression studies with subclones constructed via PCR showed that three genes (pduCDE) are necessary and sufficient for propanediol dehydratase activity. The function of ORF1 was not determined. Analyses showed that the S. typhimurium propanediol dehydratase was related to coenzyme B12-dependent glycerol dehydratases from Citrobacter freundii and Klebsiella pneumoniae. Unexpectedly, the S. typhimurium propanediol dehydratase was found to be 98% identical in amino acid sequence to the Klebsiella oxytoca propanediol dehydratase; this is a much higher identity than expected, given the relationship between these organisms. DNA sequence analyses also supported previous studies indicating that the pdu operon was inherited along with the adjacent cobalamin biosynthesis operon by a single horizontal gene transfer. PMID:9352910

  13. A multiplex oligonucleotide ligation-PCR as a complementary tool for subtyping of Salmonella Typhimurium.

    PubMed

    Wuyts, Véronique; Mattheus, Wesley; Roosens, Nancy H C; Marchal, Kathleen; Bertrand, Sophie; De Keersmaecker, Sigrid C J

    2015-10-01

    Subtyping below the serovar level is essential for surveillance and outbreak detection and investigation of Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) and its monophasic variant 1,4,[5],12:i:- (S. 1,4,[5],12:i:-), frequent causes of foodborne infections. In an attempt to overcome the intrinsic shortcomings of currently used subtyping techniques, a multiplex oligonucleotide ligation-PCR (MOL-PCR) assay was developed which combines different types of molecular markers in a high-throughput microsphere suspension array. The 52 molecular markers include prophage genes, amplified fragment length polymorphism (AFLP) elements, Salmonella genomic island 1 (SGI1), allantoinase gene allB, MLVA locus STTR10, antibiotic resistance genes, single nucleotide polymorphisms (SNPs) and phase 2 flagellar gene fljB. The in vitro stability of these markers was confirmed in a serial passage experiment. The validation of the MOL-PCR assay for subtyping of S. Typhimurium and S. 1,4,[5],12:i:- on 519 isolates shows that the method is rapid, reproducible, flexible, accessible, easy to use and relatively inexpensive. Additionally, a 100 % typeability and a discriminatory power equivalent to that of phage typing were observed, and epidemiological concordance was assessed on isolates of 2 different outbreaks. Furthermore, a data analysis method is provided so that the MOL-PCR assay allows for objective, computerised data analysis and data interpretation of which the results can be easily exchanged between different laboratories in an international surveillance network. PMID:26205523

  14. Salmonella Typhimurium Impedes Innate Immunity with a Mast Cell-Suppressing Tyrosine Phosphatase SptP

    PubMed Central

    Choi, Hae Woong; Brooking, Rhea; Neupane, Subham; Lee, Chul-Jin; Miao, Edward A.; Staats, Herman F.; Abraham, Soman N.

    2014-01-01

    Summary The virulence of Salmonella is linked to its invasive capacity and suppression of adaptive immunity. This does not explain, however, the rapid dissemination of the pathogen after breaching the gut. Here we showed that early in infection, S. Typhimurium suppressed degranulation of local mast cells (MCs), resulting in limited neutrophil recruitment and restricted outflow of vascular contents into infection sites, thus facilitating bacterial spread. MC suppression was mediated by the Salmonella phosphatase (SptP), which shares structural homology with Yersinia YopH. SptP functioned by dephosphorylating the vesicle fusion protein N-ethylmalemide-sensitive factor (NSF) and by blocking phosphorylation of Syk. Without SptP, orally challenged S. Typhimurium failed to suppress MC degranulation and exhibited limited colonization of the mesenteric lymph nodes. Administration of SptP to sites of Escherichia coli infection markedly enhanced its virulence. Thus, SptP-mediated inactivation of local MCs is a powerful mechanism utilized by S. Typhimurium to impede early innate immunity. PMID:24332031

  15. Multilocus Sequence Typing Lacks the Discriminatory Ability of Pulsed-Field Gel Electrophoresis for Typing Salmonella enterica Serovar Typhimurium

    PubMed Central

    Fakhr, Mohamed K.; Nolan, Lisa K.; Logue, Catherine M.

    2005-01-01

    Nontyphoidal salmonellae are among the leading causes of food-borne disease in the United States. Because of the importance of Salmonella enterica in food-borne disease, numerous typing methodologies have been developed. Among the several molecular typing methods, pulsed-field gel electrophoresis (PFGE) is currently considered the “gold standard” technique in typing Salmonella. The aim of this study was to compare the discriminatory power of PFGE to multilocus sequence typing (MLST) in typing Salmonella enterica serovar Typhimurium clinical isolates. A total of 85 Salmonella Typhimurium clinical isolates from cattle were used in this study. PFGE using XbaI was performed on the 85 isolates by the Centers for Disease Control and Prevention method, and data were analyzed using the BioNumerics software package. Fifty PFGE profiles were observed among the isolates, and these grouped into three major clusters. For the MLST analysis, the manB, pduF, glnA, and spaM genes were amplified by PCR from the same 85 isolates. DNA sequencing of these four genes, manB, pduF, glnA, and spaM, showed no genetic diversity among the isolates tested, with a 100% identity in nucleotide sequence. Moreover, the DNA sequences of the aforementioned genes showed 100% identity to the sequence reported in GenBank for the S. enterica serovar Typhimurium LT2 strain. Therefore, MLST, using these genes, lacks the discriminatory power of PFGE for typing Salmonella enterica serovar Typhimurium. PMID:15872244

  16. Characterization of the Genomes of a Diverse Collection of Salmonella enterica Serovar Typhimurium Definitive Phage Type 104▿

    PubMed Central

    Cooke, Fiona J.; Brown, Derek J.; Fookes, Maria; Pickard, Derek; Ivens, Alasdair; Wain, John; Roberts, Mark; Kingsley, Robert A.; Thomson, Nicholas R.; Dougan, Gordon

    2008-01-01

    Salmonella enterica serovar Typhimurium definitive phage type 104 (DT104) has caused significant morbidity and mortality in humans and animals for almost three decades. We completed the full DNA sequence of one DT104 strain, NCTC13348, and showed that significant differences between the genome of this isolate and the genome of the previously sequenced strain Salmonella serovar Typhimurium LT2 are due to integrated prophage elements and Salmonella genomic island 1 encoding antibiotic resistance genes. Thirteen isolates of Salmonella serovar Typhimurium DT104 with different pulsed-field gel electrophoresis (PFGE) profiles were analyzed by using multilocus sequence typing (MLST), plasmid profiling, hybridization to a pan-Salmonella DNA microarray, and prophage-based multiplex PCR. All the isolates belonged to a single MLST type, sequence type ST19. Microarray data demonstrated that the gene contents of the 13 DT104 isolates were remarkably conserved. The PFGE DNA fragment size differences in these isolates could be explained to a great extent by differences in the prophage and plasmid contents. Thus, here the nature of variation in different Salmonella serovar Typhimurium DT104 isolates is further defined at the gene and whole-genome levels, illustrating how this phage type evolves over time. PMID:18849424

  17. Multilocus sequence typing lacks the discriminatory ability of pulsed-field gel electrophoresis for typing Salmonella enterica serovar Typhimurium.

    PubMed

    Fakhr, Mohamed K; Nolan, Lisa K; Logue, Catherine M

    2005-05-01

    Nontyphoidal salmonellae are among the leading causes of food-borne disease in the United States. Because of the importance of Salmonella enterica in food-borne disease, numerous typing methodologies have been developed. Among the several molecular typing methods, pulsed-field gel electrophoresis (PFGE) is currently considered the "gold standard" technique in typing Salmonella. The aim of this study was to compare the discriminatory power of PFGE to multilocus sequence typing (MLST) in typing Salmonella enterica serovar Typhimurium clinical isolates. A total of 85 Salmonella Typhimurium clinical isolates from cattle were used in this study. PFGE using XbaI was performed on the 85 isolates by the Centers for Disease Control and Prevention method, and data were analyzed using the BioNumerics software package. Fifty PFGE profiles were observed among the isolates, and these grouped into three major clusters. For the MLST analysis, the manB, pduF, glnA, and spaM genes were amplified by PCR from the same 85 isolates. DNA sequencing of these four genes, manB, pduF, glnA, and spaM, showed no genetic diversity among the isolates tested, with a 100% identity in nucleotide sequence. Moreover, the DNA sequences of the aforementioned genes showed 100% identity to the sequence reported in GenBank for the S. enterica serovar Typhimurium LT2 strain. Therefore, MLST, using these genes, lacks the discriminatory power of PFGE for typing Salmonella enterica serovar Typhimurium. PMID:15872244

  18. H2-M3 Major Histocompatibility Complex Class Ib-Restricted CD8 T Cells Induced by Salmonella enterica Serovar Typhimurium Infection Recognize Proteins Released by Salmonella Serovar Typhimurium

    PubMed Central

    Ugrinovic, S.; Brooks, C. G.; Robson, J.; Blacklaws, B. A.; Hormaeche, C. E.; Robinson, J. H.

    2005-01-01

    Salmonella enterica serovar Typhimurium causes a typhoid-like disease in mice which has been studied extensively as a model for typhoid fever in humans. CD8 T cells contribute to protection against S. enterica serovar Typhimurium in mice, but little is known about the specificity and major histocompatibility complex (MHC) restriction of the response. We report here that CD8 T-cell lines derived from S. enterica serovar Typhimurium-infected BALB/c mice lysed bone marrow macrophages infected with S. enterica serovar Typhimurium or pulsed with proteins from S. enterica serovar Typhimurium culture supernatants. Cytoxicity was beta-2-microglobulin dependent and largely TAP dependent, although not MHC class Ia restricted, as target cells of several different MHC haplotypes were lysed. The data suggested the participation of class Ib MHC molecules although no evidence for the presence of Qa1-restricted T cells could be found, unlike in previous reports. Instead, the T-cell lines lysed H2-M3-transfected fibroblasts infected with S. enterica serovar Typhimurium SL3261 or treated with Salmonella culture supernatants. Thus, this report increases the number of MHC class Ib antigen-presenting molecules known for Salmonella antigens to three: Qa-1, HLA-E, and now H2-M3. It also expands the range of pathogens that induce H2-M3-restricted CD8 T cells to include an example of gram-negative bacteria. PMID:16299293

  19. Reduced leu operon expression in a miaA mutant of Salmonella typhimurium.

    PubMed Central

    Blum, P H

    1988-01-01

    Salmonella typhimurium miaA mutants lacking the tRNA base modification cis-2-methylthioribosylzeatin (ms2io6A) were examined and found to be sensitive to a variety of chemical oxidants and unable to grow aerobically at 42 degrees C in a defined medium. Leucine supplementation suppressed both of these phenotypes, suggesting that leucine synthesis was defective. Intracellular levels of leucine decreased 40-fold in mutant strains after a shift from 30 to 42 degrees C during growth, and expression of a leu-lacZ transcriptional fusion ceased. Steady-state levels of leu mRNA were also significantly reduced during growth at elevated temperatures. Failure of miaA mutant leu-lacZ expression to be fully derepressed during L-leucine limitation at 30 degrees C and suppression of the miaA mutation by a mutation in the S. typhimurium leu attenuator suggests that translational control of the transcription termination mechanism regulating leu expression is defective. Since the S. typhimurium miaA mutation was also suppressed by the Escherichia coli leu operon in trans, phenotypic differences between E. coli and S. typhimurium miaA mutants may result from a difference between their respective leu operons. Images PMID:3141379

  20. Bioprobes Based on Aptamer and Silica Fluorescent Nanoparticles for Bacteria Salmonella typhimurium Detection

    NASA Astrophysics Data System (ADS)

    Wang, Qiu-Yue; Kang, Yan-Jun

    2016-03-01

    In this study, we have developed an efficient method based on single-stranded DNA (ssDNA) aptamers along with silica fluorescence nanoparticles for bacteria Salmonella typhimurium detection. Carboxyl-modified Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate (RuBPY)-doped silica nanoparticles (COOH-FSiNPs) were prepared using reverse microemulsion method, and the streptavidin was conjugated to the surface of the prepared COOH-FSiNPs. The bacteria S. typhimurium was incubated with a specific ssDNA biotin-labeled aptamer, and then the aptamer-bacteria conjugates were treated with the synthetic streptavidin-conjugated silica fluorescence nanoprobes (SA-FSiNPs). The results under fluorescence microscopy show that SA-FSiNPs can be applied effectively for the labeling of bacteria S. typhimurium with great photostable property. To further verify the specificity of SA-FSiNPs out of multiple bacterial conditions, variant concentrations of bacteria mixtures composed of bacteria S. typhimurium, Escherichia coli, and Bacillus subtilis were treated with SA-FSiNPs.

  1. Influence of genes encoding proton-translocating enzymes on suppression of Salmonella typhimurium growth and colonization.

    PubMed

    Zhang-Barber, L; Turner, A K; Martin, G; Frankel, G; Dougan, G; Barrow, P A

    1997-11-01

    Twenty-four-hour-old, aerobically grown, Luria-Bertani broth cultures of Salmonella typhimurium F98 suppressed the growth of a spectinomycin-resistant (Spcr) derivative of the same strain inoculated at 10(3) CFU ml(-1). This growth suppression is genus specific and RpoS independent, and it is not solely a result of nutrient depletion (P. A. Barrow, M. A. Lovell, and L. Zhang-Barber, J. Bacteriol. 178:3072-3076, 1996). Mutations in three genes are shown here to significantly reduce growth suppression under these conditions. The mutations were located in the nuo, cyd, and unc operons, which code for the NADH dehydrogenase I, cytochrome d oxidase, and F0F1 proton-translocating ATPase complexes, respectively. When cultures were grown under strictly anaerobic conditions, only the unc mutant did not suppress growth. Prior colonization of the alimentary tract of newly hatched chickens with the S. typhimurium F98 wild type or nuo or cyd mutants suppressed colonization by an S. typhimurium F98 Spcr derivative inoculated 24 h later. In contrast, the S. typhimurium unc mutant did not suppress colonization. The nuo and unc mutants showed poorer growth on certain carbon sources. The data support the hypothesis that growth suppression operates because of the absence of a utilizable carbon source or electron acceptor. PMID:9371470

  2. Antibiotic Resistance in Salmonella enterica Serovar Typhimurium Associates with CRISPR Sequence Type

    PubMed Central

    DiMarzio, Michael; Shariat, Nikki; Kariyawasam, Subhashinie; Barrangou, Rodolphe

    2013-01-01

    Salmonella enterica subsp. enterica serovar Typhimurium is a leading cause of food-borne salmonellosis in the United States. The number of antibiotic-resistant isolates identified in humans is steadily increasing, suggesting that the spread of antibiotic-resistant strains is a major threat to public health. S. Typhimurium is commonly identified in a wide range of animal hosts, food sources, and environments, but little is known about the factors mediating the spread of antibiotic resistance in this ecologically complex serovar. Previously, we developed a subtyping method, CRISPR–multi-virulence-locus sequence typing (MVLST), which discriminates among strains of several common S. enterica serovars. Here, CRISPR-MVLST identified 22 sequence types within a collection of 76 S. Typhimurium isolates from a variety of animal sources throughout central Pennsylvania. Six of the sequence types were identified in more than one isolate, and we observed statistically significant differences in resistance among these sequence types to 7 antibiotics commonly used in veterinary and human medicine, such as ceftiofur and ampicillin (P < 0.05). Importantly, five of these sequence types were subsequently identified in human clinical isolates, and a subset of these isolates had identical antibiotic resistance patterns, suggesting that these subpopulations are being transmitted through the food system. Therefore, CRISPR-MVLST is a promising subtyping method for monitoring the farm-to-fork spread of antibiotic resistance in S. Typhimurium. PMID:23796925

  3. tRNA modified bases and oxidative stress in Salmonella typhimurium

    SciTech Connect

    Kramer, G.F.

    1987-01-01

    The mechanisms of toxicity of two different environmental stresses have been characterized in Salmonella typhimurium. The toxicity of near-UV (NUV) light (300-400 nm) appeared to be mediated by oxidative mechanisms. The overproduction of NUV-absorbing proteins sensitized the cells to killing by NUV. Selenium also appeared to be toxic to S. typhimurium by oxidative mechanisms. At low concentrations, the main target for this toxicity appeared to be intracellular thiols. At higher concentrations, selenite toxicity appeared to have been mediated by oxygen radicals which we have shown to be produced by the reactions of selenite with sulfhydryl groups. Such radicals may also have been involved in the selenite mutagenicity we have observed in S. typhimurium. The function of two different modified bases with respect to such oxidative stress has been characterized. The isolation of mutants lacking these bases has facilitated this investigation. S. typhimurium contained a single seleno-modified base, 5-methylaminomethyl-2-selenouridine (mnm{sup 5}Se{sup 2}U). Mutants which were unable to incorporate selenium into their tRNA (selA) were isolated based on a pleiotropic defect in selenium metabolism.

  4. RosE represses Std fimbrial expression in Salmonella enterica serotype Typhimurium

    PubMed Central

    Chessa, Daniela; Winter, Maria G; Nuccio, Sean-Paul; Tükel, Çagla; Bäumler, Andreas J

    2008-01-01

    The Salmonella enterica serotype Typhimurium (S. typhimurium) genome contains a large repertoire of putative fimbrial operons that remain poorly characterized because they are not expressed in vitro. In this study, insertions that induced expression of the putative stdABCD fimbrial operon were identified from a random bank of transposon mutants by screening with immuno-magnetic particles for ligand expression (SIMPLE). Transposon insertions upstream of csgC and lrhA or within dam, setB and STM4463 (renamed rosE) resulted in expression of StdA and its assembly into fimbrial filaments on the cell surface. RosE is a novel negative regulator of Std fimbrial expression as indicated by its repression of a std::lacZ reporter construct and by binding of the purified protein to a DNA region upstream of the stdA start codon. Expression of Std fimbriae in the rosE mutant resulted in increased attachment of S. typhimurium to human colonic epithelial cell lines (T-84 and CaCo-2). A rosE mutant exhibited a reduced ability to compete with virulent S. typhimurium for colonization of murine organs, while no defect was observed when both competing strains carried a stdAB deletion. These data suggest that a tight control of Std fimbrial expression mediated by RosE is required during host pathogen interaction. PMID:18331470

  5. Fur regulon of Salmonella typhimurium: identification of new iron-regulated genes.

    PubMed Central

    Tsolis, R M; Bäumler, A J; Stojiljkovic, I; Heffron, F

    1995-01-01

    In order to identify genes belonging to the Fur regulon of Salmonella typhimurium, a bank of 10,000 independent S. typhimurium MudJ insertion mutants was screened for lacZ fusions regulated by the iron response regulator Fur. In parallel, a plasmid gene bank of S. typhimurium consisting of 10,000 independent clones was screened for Fur-regulated promoters or iron binding proteins by the Fur titration assay (FURTA). Fur-regulated MudJ insertions and Fur-regulated promoters were mapped. In addition, iron-regulated promoter activities of transcriptional fusions from MudJ insertions and FURTA-positive clones were quantified. The nucleotide sequences of 11 FURTA-positive plasmids and of short fragments of DNA flanking three MudJ insertions were determined. By these methods we identified 14 Fur-regulated genes of S. typhimurium. For 11 of these genes, Fur-regulated homologs have been described in Escherichia coli or Yersinia enterocolitica, including fhuA,fhuB,fepA,fes,fepD,p43,entB,fur ,foxA,hemP, and fhuE. In addition, we identified three genes with homologs in other bacteria which have not previously been shown to be Fur regulated. PMID:7642488

  6. Cloning and properties of the Salmonella typhimurium tricarboxylate transport operon in Escherichia coli

    SciTech Connect

    Widenhorn, K.A.; Boos, W.; Somers, J.M.; Kay, W.W.

    1988-02-01

    The tricarboxylate transport operon (tctI) was cloned in Escherichia coli as a 12-kilobase (kb) fragment from an EcoRI library of the Salmonella typhimurium chromosome in lambdagtWES. It was further subcloned as a 12-kb fragment into pACYC184 and as an 8-kb fragment into pBR322. By insertional mutagenesis mediated by lambdaTn5, restriction mapping, and phenotypic testing, the tctI operon was localized to a 4.5-kb region. The tctC gene which encodes a periplasmic binding protein (C-protein) was located near the center of the insert. E. coli/tctI clones on either multicopy or single-copy vectors grew on the same tricarboxylates as S. typhimurium, although unusually long growth lags were observed. E. coli/tctI clones exhibited similar (/sup 14/C) fluorocitrate transport kinetics to those of S. typhimurium, whereas E. coli alone was virtually impermeable to (/sup 14/C) fluorocitrate. The periplasmic C proteins (C1 and C2 isoelectric forms) were produced in prodigious quantities from the cloned strains. Motile E. coli/tctI clones were not chemotactic toward citrate, whereas tctI deletion mutants of S. typhimurium were. Taken together, these observations indicate that tctI is not an operon involved in chemotaxis.

  7. Regulation of fucose and 1,2-propanediol utilization by Salmonella enterica serovar Typhimurium

    PubMed Central

    Staib, Lena; Fuchs, Thilo M.

    2015-01-01

    After ingestion, Salmonella enterica serovar Typhimurium (S. Typhimurium) encounters a densely populated, competitive environment in the gastrointestinal tract. To escape nutrient limitation caused by the intestinal microbiota, this pathogen has acquired specific metabolic traits to use compounds that are not metabolized by the commensal bacteria. For example, the utilization of 1,2-propanediol (1,2-PD), a product of the fermentation of L-fucose, which is present in foods of herbal origin and is also a terminal sugar of gut mucins. Under anaerobic conditions and in the presence of tetrathionate, 1,2-PD can serve as an energy source for S. Typhimurium. Comprehensive database analysis revealed that the 1,2-PD and fucose utilization operons are present in all S. enterica serovars sequenced thus far. The operon, consisting of 21 genes, is expressed as a single polycistronic mRNA. As demonstrated here, 1,2-PD was formed and further used when S. Typhimurium strain 14028 was grown with L-fucose, and the gene fucA encoding L-fuculose-1-phosphate aldolase was required for this growth. Using promoter fusions, we monitored the expression of the propanediol utilization operon that was induced at very low concentrations of 1,2-PD and was inhibited by the presence of D-glucose. PMID:26528264

  8. Crystallization and preliminary X-ray crystallographic analysis of Salmonella Typhimurium CueP.

    PubMed

    Yun, Bo-Young; Piao, Shunfu; Kim, Yeon-Gil; Moon, Hyung Ryong; Choi, Eun Joo; Kim, Young-Ok; Nam, Bo-Hye; Lee, Sang-Jun; Ha, Nam-Chul

    2011-06-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) can survive in the phagosome of macrophages, causing serious medical and veterinary problems. CueP is uniquely found in S. Typhimurium and has been characterized as a major periplasmic copper-binding protein. Although cueP has been identified as being responsible for the copper resistance of the bacterium in vivo, the biochemical role and three-dimensional structure of CueP remain unknown. In this study, CueP from S. Typhimurium was overexpressed and the recombinant protein was purified using Ni-NTA affinity, anion-exchange and gel-filtration chromatographies. The purified CueP protein was crystallized using the vapour-diffusion method. A diffraction data set was collected to 2.5 Å resolution at 100 K. The crystal belonged to space group P2(1)2(1)2(1). To obtain initial phases, selenomethionyl-substituted protein was overproduced and purified. Optimization of crystallization conditions for the selenomethionyl-substituted protein is in progress. PMID:21636909

  9. MdsABC-Mediated Pathway for Pathogenicity in Salmonella enterica Serovar Typhimurium

    PubMed Central

    Song, Saemee; Lee, Boeun; Yeom, Ji-Hyun; Hwang, Soonhye; Kang, Ilnam; Cho, Jang-Cheon; Ha, Nam-Chul; Bae, Jeehyeon

    2015-01-01

    MdsABC is a Salmonella-specific tripartite efflux pump that has been implicated in the virulence of Salmonella enterica serovar Typhimurium; however, little is known about the virulence factors associated with this pump. We observed MdsABC expression-dependent alterations in the degree of resistance to extracellular oxidative stress and macrophage-mediated killing. Thin-layer chromatography and tandem mass spectrometry analyses revealed that overexpression of MdsABC led to increased secretion of 1-palmitoyl-2-stearoyl-phosphatidylserine (PSPS), affecting the ability of the bacteria to invade and survive in host cells. Overexpression of MdsABC and external addition of PSPS similarly rendered the mdsABC deletion strain resistant to diamide. Diagonal gel analysis showed that PSPS treatment reduced the diamide-mediated formation of disulfide bonds, particularly in the membrane fraction of the bacteria. Salmonella infection of macrophages induced the upregulation of MdsABC expression and led to an increase of intracellular bacterial number and host cell death, similar to the effects of MdsABC overexpression and PSPS pretreatment on the mdsABC deletion strain. Our study shows that MdsABC mediates a previously uncharacterized pathway that involves PSPS as a key factor for the survival and virulence of S. Typhimurium in phagocytic cells. PMID:26283336

  10. Assessment of 2 Salmonella enterica serovar Typhimurium-based vaccines against necrotic enteritis in reducing colonization of chickens by Salmonella serovars of different serogroups.

    PubMed

    Jiang, Yanfen; Kulkarni, Raveendra R; Parreira, Valeria R; Poppe, Cornelius; Roland, Kenneth L; Prescott, John F

    2010-10-01

    This study assessed the protective efficacy of oral vaccination with 2 experimental attenuated Salmonella Typhimurium-vectored vaccines for necrotic enteritis in protecting chickens against intestinal colonization by common serovars of Salmonella belonging to the 4 major serogroups affecting chickens. Birds were vaccinated orally with 1 × 10⁸ colony-forming units (CFU) of 1 of the vaccine strains χ9241 and χ9352, which express a plasmid-encoded partial recombinant hypothetical protein gene (tHP) of Clostridium perfringens, at days 1 and 7 of age, and then were challenged at 14 d of age with 10⁶ CFU of Salmonella serovars Anatum, Enteritidis, Heidelberg, Kentucky, or Typhimurium (representative serovars of serogroups B, C, D, and E). Birds were necropsied at 4 wk of age, and samples were collected to determine reduction in tissue and intestinal colonization. The chickens vaccinated with χ9241-tHP showed reduced colonization by Salmonella Enteritidis (serogroup D) and by Salmonella Heidelberg and Salmonella Typhimurium (serogroup B) compared with the control birds. No reduction in colonization was observed in the chickens vaccinated with χ9352-tHP. There was an association between the efficacy of these vaccine strains in protecting against necrotic enteritis, assessed on an earlier occasion, and their efficacy in protecting against Salmonella colonization. Thus, the choice of an attenuated Salmonella Typhimurium vaccine vector for delivery of heterologous antigens to chickens should be based partly on the vaccine's value in protecting against colonization by serovars within serogroups B and D. Such vectors would have the additional benefit of reducing colonization of important Salmonella serovars. PMID:21197226

  11. The Salmonella typhimurium mar locus: molecular and genetic analyses and assessment of its role in virulence.

    PubMed Central

    Sulavik, M C; Dazer, M; Miller, P F

    1997-01-01

    The marRAB operon is a regulatory locus that controls multiple drug resistance in Escherichia coli. marA encodes a positive regulator of the antibiotic resistance response, acting by altering the expression of unlinked genes. marR encodes a repressor of marRAB transcription and controls the production of MarA in response to environmental signals. A molecular and genetic study of the homologous operon in Salmonella typhimurium was undertaken, and the role of marA in virulence in a murine model was assessed. Expression of E. coli marA (marAEC) present on a multicopy plasmid in S. typhimurium resulted in a multiple antibiotic resistance (Mar) phenotype, suggesting that a similar regulon exists in this organism. A genomic plasmid library containing S. typhimurium chromosomal sequences was introduced into an E. coli strain that was deleted for the mar locus and contained a single-copy marR'-'lacZ translational fusion. Plasmid clones that contained both S. typhimurium marR (marRSt) and marA (marASt) genes were identified as those that were capable of repressing expression of the fusion and which resulted in a Mar phenotype. The predicted amino acid sequences of MarRSt, MarASt, and MarBSt were 91, 86, and 42% identical, respectively, to the same genes from E. coli, while the operator/promoter region of the operon was 86% identical to the same 98-nucleotide-upstream region in E. coli. The marRAB transcriptional start sites for both organisms were determined by primer extension, and a marRABSt transcript of approximately 1.1 kb was identified by Northern blot analysis. Its accumulation was shown to be inducible by sodium salicylate. Open reading frames flanking the marRAB operon were also conserved. An S. typhimurium marA disruption strain was constructed by an allelic exchange method and compared to the wild-type strain for virulence in a murine BALB/c infection model. No effect on virulence was noted. The endogenous S. typhimurium plasmid that is associated with virulence

  12. Inherent Variability of Growth Media Impacts the Ability of Salmonella Typhimurium to Interact with Host Cells

    PubMed Central

    Sridhar, Sushmita; Steele-Mortimer, Olivia

    2016-01-01

    Efficient invasion of non-phagocytic cells, such as intestinal epithelial cells, by Salmonella Typhimurium is dependent on the Salmonella Pathogenicity Island 1 (SPI-1)-encoded Type Three Secretion System. The environmental cues involved in SPI-1 induction are not well understood. In vitro, various conditions are used to induce SPI-1 and the invasive phenotype. Although lysogeny broth (LB) is widely used, multiple formulations exist, and variation can arise due to intrinsic differences in complex components. Minimal media are also susceptible to variation. Still, the impact of these inconsistencies on Salmonella virulence gene expression has not been well studied. The goal of this project is to identify growth conditions in LB and minimal medium that affect SPI-1 induction in vitro using both whole population and single cell analysis. Here we show, using a fluorescent reporter of the SPI-1 gene prgH, that growth of Salmonella in LB yields variable induction. Deliberate modification of media components can influence the invasive profile. Finally, we demonstrate that changes in SPI-1 inducing conditions can affect the ability of Salmonella to replicate intracellularly. These data indicate that the specific media growth conditions impact how the bacteria interact with host cells. PMID:27280414

  13. Inactivation kinetics and virulence potential of Salmonella Typhimurium and Listeria monocytogenes treated by combined high pressure and nisin.

    PubMed

    Gou, Jingyu; Lee, Hyeon-Yong; Ahn, Juhee

    2010-12-01

    The aim of this study was to characterize the physiological and molecular changes of Salmonella Typhimurium and Listeria monocytogenes in deionized water (DIW) and nisin solutions (100 IU/g) during high pressure processing (HPP). Strains of Salmonella Typhimurium and L. monocytogenes in DIW or nisin solutions were subjected to 200, 300, and 400 MPa for 20 min. The Weibull model adequately described the HPP inactivation of Salmonella Typhimurium and L. monocytogenes. Salmonella Typhimurium and L. monocytogenes populations were reduced to less than 1 CFU/ml in DIW and nisin solutions under 400 MPa. The highest b value was 5.75 for Salmonella Typhimurium in nisin solution under 400 MPa. L. monocytogenes was more sensitive to pressure change when suspended in DIW than when suspended in nisin. The pressure sensitivity of both Salmonella Typhimurium and L. monocytogenes was higher in DIW solution (141 to 243 MPa) than in nisin solution (608 to 872 MPa). No recovery of HPP-injured cells in DIW and nisin solutions treated at 400 MPa was observed after 7 days of refrigerated storage. The heterogeneity of HPP-treated cells was revealed in flow cytometry dot plots. The transcripts of stn, invA, prfA, and inlA were relatively down-regulated in HPP-treated nisin solution. The combination of high pressure and nisin could noticeably suppress the expression of virulence-associated genes. These results provide useful information for understanding the physiological and molecular characteristics of foodborne pathogens under high-pressure stress. PMID:21219737

  14. A comparative study of thermal and acid inactivation kinetics in fruit juices of Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Senftenberg grown at acidic conditions.

    PubMed

    Alvarez-Ordóñez, Avelino; Fernández, Ana; Bernardo, Ana; López, Mercedes

    2009-11-01

    Acid and heat inactivation in orange and apple juices of Salmonella enterica serovar Typhimurium Colección Española de Cultivos Tipo (i.e., Spanish Type Culture Collection) 443 (CECT 443) (Salmonella Typhimurium) and S. enterica serovar Senftenberg CECT 4384 (Salmonella Senftenberg) grown in buffered brain heart infusion (pH 7.0) and acidified brain heart infusion up to pH 4.5 with acetic, citric, lactic, and hydrochloric acids was evaluated. Acid adaptation induced an adaptive response that increased the subsequent resistance to extreme pH conditions (pH 2.5) and to heat, although the magnitude of these responses differed between the two isolates and fruit juices. The acid resistance in orange juice for acid-adapted cells (D-values of 28.3-34.5 min for Salmonella Senftenberg and 30.0-39.2 min for Salmonella Typhimurium) resulted to be about two to three times higher than that corresponding to non-acid-adapted cells. In apple juice, acid-adapted Salmonella Senftenberg cells survived better than those of Salmonella Typhimurium, obtaining mean D-values of 114.8 +/- 12.3 and 41.9 +/- 2.5 min, respectively. The thermotolerance of non-acid-adapted Salmonella Typhimurium in orange (D(58)-value: 0.028 min) and apple juices (D(58)-value: 0.10 min) was approximately double for acid-adapted cells. This cross-protection to heat was more strongly expressed in Salmonella Senftenberg. D(58)-values obtained for non-acid-adapted cells in orange (0.11 min) and apple juices (0.19 min) increased approximately 10 and 5 times, respectively, after their growth in acidified media. The conditions prevailing during bacterial growth and heat treatment did not significantly influence the z-values observed (6.0 +/- 0.3 degrees C for Salmonella Typhimurium and 7.0 +/- 0.3 degrees C for Salmonella Senftenberg). The enhanced acid resistance found for both isolates could enable them to survive for prolonged time periods in the gastrointestinal tract, increasing the risk of illness. Further, it

  15. Bacteriophages with potential to inactivate Salmonella Typhimurium: Use of single phage suspensions and phage cocktails.

    PubMed

    Pereira, Carla; Moreirinha, Catarina; Lewicka, Magdalena; Almeida, Paulo; Clemente, Carla; Cunha, Ângela; Delgadillo, Ivonne; Romalde, Jésus L; Nunes, Maria L; Almeida, Adelaide

    2016-07-15

    The aim of this study was to compare the dynamics of three previously isolated bacteriophages (or phages) individually (phSE-1, phSE-2 and phSE-5) or combined in cocktails of two or three phages (phSE-1/phSE-2, phSE-1/phSE-5, phSE-2/phSE-5 and phSE-1/phSE-2/phSE-5) to control Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) in order to evaluate their potential application during depuration. Phages were assigned to the family Siphoviridae and revealed identical restriction digest profiles, although they showed a different phage adsorption, host range, burst size, explosion time and survival in seawater. The three phages were effective against S. Typhimurium (reduction of ∼2.0 log CFU/mL after 4h treatment). The use of cocktails was not significantly more effective than the use of single phages. A big fraction of the remained bacteria are phage-resistant mutants (frequency of phage-resistant mutants 9.19×10(-5)-5.11×10(-4)) but phage- resistant bacterial mutants was lower for the cocktail phages than for the single phage suspensions and the phage phSE-1 presented the highest rate of resistance and phage phSE-5 the lowest one. The spectral changes of S. Typhimurium resistant and phage-sensitive cells were compared and revealed relevant differences for peaks associated to amide I (1620cm(-1)) and amide II (1515cm(-1)) from proteins and from carbohydrates and phosphates region (1080-1000cm(-1)). Despite the similar efficiency of individual phages, the development of lower resistance indicates that phage cocktails might be the most promising choice to be used during the bivalve depuration to control the transmission of salmonellosis. PMID:27126773

  16. Tumor-targeting Salmonella typhimurium A1-R inhibits human prostate cancer experimental bone metastasis in mouse models

    PubMed Central

    Toneri, Makoto; Miwa, Shinji; Zhang, Yong; Hu, Cameron; Yano, Shuya; Matsumoto, Yasunori; Bouvet, Michael; Nakanishi, Hayao; Hoffman, Robert M.; Zhao, Ming

    2015-01-01

    Bone metastasis is a frequent occurrence in prostate cancer patients and often is lethal. Zoledronic acid (ZOL) is often used for bone metastasis with limited efficacy. More effective models and treatment methods are required to improve the outcome of prostate cancer patients. In the present study, the effects of tumor-targeting Salmonella typhimurium A1-R were analyzed in vitro and in vivo on prostate cancer cells and experimental bone metastasis. Both ZOL and S. typhimurium A1-R inhibited the growth of PC-3 cells expressing red fluorescent protien in vitro. To investigate the efficacy of S. typhimurium A1-R on prostate cancer experimental bone metastasis, we established models of both early and advanced stage bone metastasis. The mice were treated with ZOL, S. typhimurium A1-R, and combination therapy of both ZOL and S. typhimurium A1-R. ZOL and S. typhimurium A1-R inhibited the growth of solitary bone metastases. S. typhimurium A1-R treatment significantly decreased bone metastasis and delayed the appearance of PC-3 bone metastases of multiple mouse models. Additionally, S. typhimurium A1-R treatment significantly improved the overall survival of the mice with multiple bone metastases. The results of the present study indicate that S. typhimurium A1-R is useful to prevent and inhibit prostate cancer bone metastasis and has potential for future clinical use in the adjuvant setting. PMID:26431498

  17. 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

  18. Antimicrobial effect of Thai spices against Listeria monocytogenes and Salmonella typhimurium DT104.

    PubMed

    Thongson, Chitsiri; Davidson, P Michael; Mahakarnchanakul, Warapa; Vibulsresth, Preeya

    2005-10-01

    The objective of this study was to determine the potential antimicrobial activity of extracts and essential oils of spices from Thailand against foodborne pathogenic bacteria. The antimicrobial efficacy of ginger (Zingiber officinale), fingerroot (Boesenbergia pandurata), and turmeric (Curcuma longa) was evaluated against five strains of Listeria monocytogenes and four strains of Salmonella enterica ssp. enterica serovar Typhimurium DT104. Antimicrobial activity was investigated in microbiological media by using an agar dilution assay and enumeration over time and a model food system, apple juice, by monitoring growth over time. In the agar dilution assay, water extracts of the three spices had no effect on L. monocytogenes. Similarly, 50% ethanol extracts of ginger or turmeric had no effect. In contrast, ethanolic fingerroot extracts at 5 to 10% (vol/ vol) inhibited most L. monocytogenes strains for 24 h in the agar dilution assay. Commercial essential oils (EO) of ginger or turmeric inhibited all L. monocytogenes at < or = 0.6 or < or = 10%, respectively. Fingerroot EO inhibited all strains at < or = 0.4%. In the enumeration-over-time assay, a 5% fingerroot ethanol extract reduced ca. 4 log CFU/ml Listeria by around 2 log in 24 h while 10% inactivated the microorganism in 9 h. Fingerroot EO at 0.2% inactivated 4 log CFU/ml L. monocytogenes in 6 to 9 h. Neither extracts nor commercial EO had any effect on Salmonella Typhimurium DT 104 with the exception of fingerroot EO, which inhibited all strains at < or = 0.7%. Addition of 0.2% fingerroot EO to apple juice reduced 4 log of L. monocytogenes Scott A and both strains of Salmonella Typhimurium to an undetectable level within 1 to 2 days. It was concluded that fingerroot EO and extract have potential for inhibiting pathogens in food systems. PMID:16245707

  19. The complete plasmid sequences of Salmonella enterica serovar Typhimurium U288.

    PubMed

    Hooton, Steven P T; Timms, Andrew R; Cummings, Nicola J; Moreton, Joanna; Wilson, Ray; Connerton, Ian F

    2014-08-28

    Salmonella enterica Serovar Typhimurium U288 is an emerging pathogen of pigs. The strain contains three plasmids of diverse origin that encode traits that are of concern for food security and safety, these include antibiotic resistant determinants, an array of functions that can modify cell physiology and permit genetic mobility. At 148,711 bp, pSTU288-1 appears to be a hybrid plasmid containing a conglomerate of genes found in pSLT of S. Typhimurium LT2, coupled with a mosaic of horizontally-acquired elements. Class I integron containing gene cassettes conferring resistance against clinically important antibiotics and compounds are present in pSTU288-1. A curious feature of the plasmid involves the deletion of two genes encoded in the Salmonella plasmid virulence operon (spvR and spvA) following the insertion of a tnpA IS26-like element coupled to a blaTEM gene. The spv operon is considered to be a major plasmid-encoded Salmonella virulence factor that is essential for the intracellular lifecycle. The loss of the positive regulator SpvR may impact on the pathogenesis of S. Typhimurium U288. A second 11,067 bp plasmid designated pSTU288-2 contains further antibiotic resistance determinants, as well as replication and mobilization genes. Finally, a small 4675 bp plasmid pSTU288-3 was identified containing mobilization genes and a pleD-like G-G-D/E-E-F conserved domain protein that modulate intracellular levels of cyclic di-GMP, and are associated with motile to sessile transitions in growth. PMID:25175817

  20. Ethanolamine Utilization Contributes to Proliferation of Salmonella enterica Serovar Typhimurium in Food and in Nematodes▿

    PubMed Central

    Srikumar, Shabarinath; Fuchs, Thilo M.

    2011-01-01

    Only three pathogenic bacterial species, Salmonella enterica, Clostridium perfringens, and Listeria monocytogenes, are able to utilize both ethanolamine and 1,2-propanediol as a sole carbon source. Degradation of these substrates, abundant in food and the gut, depends on cobalamin, which is synthesized de novo only under anaerobic conditions. Although the eut, pdu, and cob-cbi gene clusters comprise 40 kb, the conditions under which they confer a selection advantage on these food-borne pathogens remain largely unknown. Here we used the luciferase reporter system to determine the response of the Salmonella enterica serovar Typhimurium promoters PeutS, PpocR, PpduF, and PpduA to a set of carbon sources, to egg yolk, to whole milk, and to milk protein or fat fractions. Depending on the supplements, specific inductions up to 3 orders of magnitude were observed for PeutS and PpduA, which drive the expression of most eut and pdu genes. To correlate these significant expression data with growth properties, nonpolar deletions of pocR, regulating the pdu and cob-cbi genes, and of eutR, involved in eut gene activation, were constructed in S. Typhimurium strain 14028. During exponential growth of the mutants 14028ΔpocR and 14028ΔeutR, 2- to 3-fold-reduced proliferation in milk and egg yolk was observed. Using the Caenorhabditis elegans infection model, we could also demonstrate that the proliferation of S. Typhimurium in the nematode is supported by an active ethanolamine degradation pathway. Taking these findings together, this study quantifies the differential expression of eut and pdu genes under distinct conditions and provides experimental evidence that the ethanolamine utilization pathway allows salmonellae to occupy specific metabolic niches within food environments and within their host organisms. PMID:21037291

  1. Identification of Novel Factors Involved in Modulating Motility of Salmonella enterica Serotype Typhimurium

    PubMed Central

    Bogomolnaya, Lydia M.; Aldrich, Lindsay; Ragoza, Yuri; Talamantes, Marissa; Andrews, Katharine D.; McClelland, Michael; Andrews-Polymenis, Helene L.

    2014-01-01

    Salmonella enterica serotype Typhimurium can move through liquid using swimming motility, and across a surface by swarming motility. We generated a library of targeted deletion mutants in Salmonella Typhimurium strain ATCC14028, primarily in genes specific to Salmonella, that we have previously described. In the work presented here, we screened each individual mutant from this library for the ability to move away from the site of inoculation on swimming and swarming motility agar. Mutants in genes previously described as important for motility, such as flgF, motA, cheY are do not move away from the site of inoculation on plates in our screens, validating our approach. Mutants in 130 genes, not previously known to be involved in motility, had altered movement of at least one type, 9 mutants were severely impaired for both types of motility, while 33 mutants appeared defective on swimming motility plates but not swarming motility plates, and 49 mutants had reduced ability to move on swarming agar but not swimming agar. Finally, 39 mutants were determined to be hypermotile in at least one of the types of motility tested. Both mutants that appeared non-motile and hypermotile on plates were assayed for expression levels of FliC and FljB on the bacterial surface and many of them had altered levels of these proteins. The phenotypes we report are the first phenotypes ever assigned to 74 of these open reading frames, as they are annotated as ‘hypothetical genes’ in the Typhimurium genome. PMID:25369209

  2. Inactivation of Enterobacter sakazakii, Bacillus cereus, and Salmonella typhimurium in powdered weaning food by electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Hong, Yun-Hee; Park, Ji-Yong; Park, Jong-Hyun; Chung, Myong-Soo; Kwon, Ki-Sung; Chung, Kyungsook; Won, Misun; Song, Kyung-Bin

    2008-09-01

    Inactivation of Enterobacter sakazakii, Bacillus cereus, and Salmonella typhimurium were evaluated in powdered weaning food using electron-beam irradiation. E. sakazakii, B. cereus, and S. typhimurium were eliminated by irradiation at 16, 8, and 8 kGy, respectively. The D10-vlaues of E. sakazakii, B. cereus, and S. typhimurium inoculated on powdered weaning food were 4.83, 1.22, and 0.98 kGy, respectively. The results suggest that electron-beam irradiation should inhibit the growth of pathogenic bacteria on baby food without impairing qualities.

  3. A colonisation-inhibition culture consisting of Salmonella Enteritidis and Typhimurium ΔhilAssrAfliG strains protects against infection by strains of both serotypes in broilers.

    PubMed

    De Cort, W; Mot, D; Haesebrouck, F; Ducatelle, R; Van Immerseel, F

    2014-08-01

    Consumption of contaminated poultry meat is still an important cause of Salmonella infections in humans and there is a need for control methods that protect broilers from day-of-hatch until slaughter age against infection with Salmonella. Colonisation-inhibition, a concept in which a live Salmonella strain is orally administered to day-old chickens and protects against subsequent challenge, can potentially be used as control method. In this study, the efficacy of a Salmonella Typhimurium ΔhilAssrAfliG strain as a colonisation-inhibition strain for protection of broilers against Salmonella Typhimurium was evaluated. Administration of a Salmonella Typhimurium ΔhilAssrAfliG strain to day-old broiler chickens decreased faecal shedding and strongly reduced caecal and internal organ colonisation of a Salmonella Typhimurium challenge strain administered one day later using a seeder bird model. In addition, it was verified whether a colonisation-inhibition culture could be developed that protects against both Salmonella Enteritidis and Typhimurium. Therefore, the Salmonella Typhimurium ΔhilAssrAfliG strain was orally administered simultaneously with a Salmonella Enteritidis ΔhilAssrAfliG strain to day-old broiler chickens, which resulted in a decreased caecal and internal organ colonisation for both a Salmonella Enteritidis and a Salmonella Typhimurium challenge strain short after hatching, using a seeder bird model. The combined culture was not protective against Salmonella Paratyphi B varietas Java challenge, indicating serotype-specific protection mechanisms. The data suggest that colonisation-inhibition can potentially be used as a versatile control method to protect poultry against several Salmonella serotypes. PMID:24975814

  4. Detection of Salmonella typhimurium in dairy products with flow cytometry and monoclonal antibodies.

    PubMed Central

    McClelland, R G; Pinder, A C

    1994-01-01

    Flow cytometry, combined with fluorescently labelled monoclonal antibodies, offers advantages of speed and sensitivity for the detection of specific pathogenic bacteria in foods. We investigated the detection of Salmonella typhimurium in eggs and milk. Using a sample clearing procedure, we determined that the detection limit was on the order of 10(3) cells per ml after a total analysis time of 40 min. After 6 h of nonselective enrichment, the detection limits were 10 cells per ml for milk and 1 cell per ml for eggs, even in the presence of a 10,000-fold excess of Escherichia coli cells. Images PMID:7811064

  5. Interaction of Salmonella Typhimurium with Dendritic Cells Derived from Pluripotent Embryonic Stem Cells

    PubMed Central

    Rossi, Raffaella; Hale, Christine; Goulding, David; Andrews, Robert; Abdellah, Zarah; Fairchild, Paul J.; Dougan, Gordon

    2012-01-01

    Using an in vitro differentiation protocol we isolated cells with the properties of dendritic cells (DCs) from immunologically refractive pluripotent murine embryonic stem cells (ESCs). These ES-derived dendritic cells (ESDCs) expressed cytokines and were able to present antigen to a T cell line. Infection of ESDCs with Salmonella Typhimurium stimulated the expression of immune cell markers and thousands of murine genes, many associated with the immune response. Consequently, this system provides a novel in vitro model, amenable to genetic modification, for monitoring host/pathogen interactions. PMID:23284947

  6. Incorporation of phosphatidylglycerol into murein lipoprotein in intact cells of Salmonella typhimurium by phospholipid vesicle fusion.

    PubMed Central

    Chattopadhyay, P K; Lai, J S; Wu, H C

    1979-01-01

    The biosynthesis of the diglyceride moiety of murein lipoprotein was studied by fusion of labeled phospholipid vesicles with intact cells of Salmonella typhimurium. Phosphatidylglycerol was found to be an excellent donor for the glyceryl moiety in lipoprotein, whereas phosphatidylethanolamine and cardiolipin were not. The incorporation of radioactivity from monoacyl-phosphatidylglycerol into lipoprotein can be attributed to its conversion to phosphatidylglycerol. The results strongly support our hypothesis that the glyceryl residue covalently linked to murein lipoprotein is derived from the nonacylated glycerol moiety of phosphatidylglycerol. PMID:368018

  7. Salmonella typhimurium mutants defective in acetohydroxy acid synthases I and II.

    PubMed

    Shaw, K J; Berg, C M; Sobol, T J

    1980-03-01

    An analysis of transposon-induced mutants shows that Salmonella typhimurium possesses two major isozymes of acetohydroxy acid synthase, the enzymes which mediate the first common step in isoleucine and valine biosynthesis. A third (minor) acetohydroxy acid synthase is present, but its significance in isoleucine and valine synthesis may be negligible. Mutants defective in acetohydroxy acid synthase II (ilvG::Tn10) require isoleucine, alpha-ketobutyrate, or threonine for growth, a mutant defective in acetohydroxy acid synthase I (ilvB::Tn5) is a prototroph, and a double mutant (ilvG::Tn10 ilvB::Tn5) requires isoleucine plus valine for growth. PMID:6245063

  8. Quantifying the toxic and mutagenic activity of complex mixtures with Salmonella typhimurium

    SciTech Connect

    Somani, S.M.; Schaeffer, D.J.; Mack, J.O.

    1981-03-01

    The toxicity and mutagenicity of 11 compounds individually and in mixtures were quantified in Salmonella typhimurium strains TA98, TA100, and TA1537 by a modification of the Ames spot test. The distance (millimeters) from the center of the petri dish to the bacterial growth front represented the toxic response. When mutagenicity occurred, the distance from the inner radius to the outer radius of the mutagenic growth represented the mutagenic response. Multiple regression analysis was used to quantify the toxicity and mutagenicity of individual compounds in the mixtures. The results indicate that the effects of compounds in mixtures are generally additive.

  9. L-Asparaginase delivered by Salmonella typhimurium suppresses solid tumors

    PubMed Central

    Kim, Kwangsoo; Jeong, Jae Ho; Lim, Daejin; Hong, Yeongjin; Lim, Hyung-Ju; Kim, Geun-Joong; Shin, So-ra; Lee, Je-Jung; Yun, Misun; Harris, Robert A; Min, Jung-Joon; Choy, Hyon E

    2015-01-01

    Bacteria can be engineered to deliver anticancer proteins to tumors via a controlled expression system that maximizes the concentration of the therapeutic agent in the tumor. L-asparaginase (L-ASNase), which primarily converts asparagine to aspartate, is an anticancer protein used to treat acute lymphoblastic leukemia. In this study, Salmonellae were engineered to express L-ASNase selectively within tumor tissues using the inducible araBAD promoter system of Escherichia coli. Antitumor efficacy of the engineered bacteria was demonstrated in vivo in solid malignancies. This result demonstrates the merit of bacteria as cancer drug delivery vehicles to administer cancer-starving proteins such as L-ASNase to be effective selectively within the microenvironment of cancer tissue. PMID:27119104

  10. Cluster of genes controlling proline degradation in Salmonella typhimurium.

    PubMed Central

    Ratzkin, B; Roth, J

    1978-01-01

    A cluster of genes essential for degradation of proline to glutamate (put) is located between the pyrC and pyrD loci at min 22 of the Salmonella chromosome. A series of 25 deletion mutants of this region have been isolated and used to construct a fine-structure map of the put genes. The map includes mutations affecting the proline degradative activities, proline oxidase and pyrroline-5-carboxylic dehydrogenase. Also included are mutations affecting the major proline permease and a regulatory mutation that affects both enzyme and permease production. The two enzymatic activities appear to be encoded by a single gene (putA). The regulatory mutation maps between the putA gene and the proline permease gene (putP). PMID:342507

  11. Immunogenicity of transmissible gastroenteritis virus (TGEV) M gene delivered by attenuated Salmonella typhimurium in mice.

    PubMed

    Qing, Ying; Liu, Jiawen; Huang, Xiaobo; Li, Yaqing; Zhang, Yudi; Chen, Jie; Wen, Xintian; Cao, Sanjie; Wen, Yiping; Wu, Rui; Yan, Qigui; Ma, Xiaoping

    2016-04-01

    Attenuated Salmonella typhimurium (S. typhimurium) was selected as a transgenic vehicle for the development of live mucosal vaccines against transmissible gastroenteritis virus (TGEV) based on the M gene. An approximate 1.0 kb DNA fragment, encoding for glycoprotein M, was amplified by RT-PCR and cloned into eukaryotic expression vector pVAX1. The recombinant plasmid pVAX-M was transformed by electroporation into attenuated S. typhimurium SL7207, and the expression and translation of the pVAX-M delivered by recombinant S. typhimurium SL7207 (pVAX-M) was detected both in vitro and in vivo. BALB/c mice were inoculated orally with SL7207 (pVAX-M) at different dosages to evaluate safety of the vaccines. The bacterium was safe to mice at a dosage of 2 × 10(9) CFU, almost eliminated from the spleen and liver at week 4 post-immunization and eventually cleared at week 6. Mice immunized with 1 × 10(9) CFU of SL7207 (pVAX-M) elicited specific anti-TGEV local mucosal and humoral responses including levels of IgA, IgG, IL-4, and IFN-γ as measured by indirect ELISA assay. Moreover, the control groups (pVAX group, PBS group) maintained at a normal level during week 4-8 post-immunization. The results indicated that attenuated S. typhimurium could be used as a delivery vector for oral immunization of TGEV M gene vaccine. PMID:26837896

  12. Genomic Subtractive Hybridization and Selective Capture of Transcribed Sequences Identify a Novel Salmonella typhimurium Fimbrial Operon and Putative Transcriptional Regulator That Are Absent from the Salmonella typhi Genome

    PubMed Central

    Morrow, Brian J.; Graham, James E.; Curtiss, Roy

    1999-01-01

    Salmonella typhi, the etiologic agent of typhoid fever, is adapted to the human host and unable to infect nonprimate species. The genetic basis for host specificity in S. typhi is unknown. The avirulence of S. typhi in animal hosts may result from a lack of genes present in the broad-host-range pathogen Salmonella typhimurium. Genomic subtractive hybridization was successfully employed to isolate S. typhimurium genomic sequences which are absent from the S. typhi genome. These genomic subtracted sequences mapped to 17 regions distributed throughout the S. typhimurium chromosome. A positive cDNA selection method was then used to identify subtracted sequences which were transcribed by S. typhimurium following macrophage phagocytosis. A novel putative transcriptional regulator of the LysR family was identified as transcribed by intramacrophage S. typhimurium. This putative transcriptional regulator was absent from the genomes of the human-adapted serovars S. typhi and Salmonella paratyphi A. Mutations within this gene did not alter the level of S. typhimurium survival within macrophages or virulence within mice. A subtracted genomic fragment derived from the ferrichrome operon also hybridized to the intramacrophage cDNA. Nucleotide sequence analysis of S. typhimurium and S. typhi chromosomal sequences flanking the ferrichrome operon identified a novel S. typhimurium fimbrial operon with a high level of similarity to sequences encoding Proteus mirabilis mannose-resistant fimbriae. The novel fimbrial operon was absent from the S. typhi genome. The absence of specific genes may have allowed S. typhi to evolve as a highly invasive, systemic human pathogen. PMID:10496884

  13. Global Analysis of Host and Bacterial Ubiquitinome in Response to Salmonella Typhimurium Infection.

    PubMed

    Fiskin, Evgenij; Bionda, Tihana; Dikic, Ivan; Behrends, Christian

    2016-06-16

    Ubiquitination serves as a critical signal in the host immune response to infection. Many pathogens have evolved strategies to exploit the ubiquitin (Ub) system to promote their own survival through a complex interplay between host defense machinery and bacterial virulence factors. Here we report dynamic changes in the global ubiquitinome of host epithelial cells and invading pathogen in response to Salmonella Typhimurium infection. The most significant alterations in the host ubiquitinome concern components of the actin cytoskeleton, NF-κB and autophagy pathways, and the Ub and RHO GTPase systems. Specifically, infection-induced ubiquitination promotes CDC42 activity and linear ubiquitin chain formation, both being required for NF-κB activation. Conversely, the bacterial ubiquitinome exhibited extensive ubiquitination of various effectors and several outer membrane proteins. Moreover, we reveal that bacterial Ub-modifying enzymes modulate a unique subset of host targets, affecting different stages of Salmonella infection. PMID:27211868

  14. Development and evaluation of an experimental vaccination program using a live avirulent Salmonella typhimurium strain to protect immunized chickens against challenge with homologous and heterologous Salmonella serotypes.

    PubMed Central

    Hassan, J O; Curtiss, R

    1994-01-01

    A stable live avirulent, genetically modified delta cya delta crp Salmonella typhimurium vaccine strain, chi 3985, was used in several vaccination strategies to evaluate its use in the control of Salmonella infection in chickens. Oral vaccination of chickens at 1 and at 14 days of age with 10(8) CFU of chi 3985 protected against invasion of spleen, ovary, and bursa of Fabricius and colonization of the ileum and cecum in chickens challenged with 10(6) CFU of virulent homologous Salmonella strains from group B. Chickens challenged with heterologous Salmonella strains from groups C, D, and E were protected against visceral invasion of spleen and ovary, while invasion of the bursa of Fabricius and colonization of ileum and cecum was reduced in vaccinated chickens. Oral vaccination at 2 and at 4 weeks of age induced an excellent protection against challenge with virulent group B Salmonella serotypes and very good protection against challenge with group D or E Salmonella serotypes, while protection against challenge with group C Salmonella serotypes was marginal but significant. Vaccination at 2 and at 4 weeks of age also protected vaccinated chickens against challenge with 10(8) CFU of highly invasive S. typhimurium or S. enteritidis strains. The protection of chickens vaccinated with chi 3985 against challenge with homologous and heterologous Salmonella serotypes is outstanding, and the complete protection against ovarian invasion in chickens challenged with 10(8) CFU of highly invasive S. typhimurium or S. enteritidis strains suggests that vaccination of chickens with chi 3985 can complement the present hygiene- and sanitation-based Salmonella control measures. This paper reports a breakthrough in the use of live avirulent vaccine to control Salmonella carriers in chickens. PMID:7960134

  15. Magnetic focusing immunosensor for the detection of Salmonella typhimurium in foods

    NASA Astrophysics Data System (ADS)

    Pivarnik, Philip E.; Cao, He; Letcher, Stephen V.; Pierson, Arthur H.; Rand, Arthur G.

    1999-01-01

    From 1988 through 1992 Salmonellosis accounted for 27% of the total reported foodborne disease outbreaks and 57% of the outbreaks in which the pathogen was identified. The prevalence of Salmonellosis and the new requirements to monitor the organism as a marker in pathogen reduction programs will drive the need for rapid, on-site testing. A compact fiber optic fluorometer using a red diode laser as an excitation source and fiber probes for analyte detection has been constructed and used to measure Salmonella. The organisms were isolated with anti-Salmonella magnetic beads and were labeled with a secondary antibody conjugated to a red fluorescent dye. The response of the system was proportional to the concentration of Salmonella typhimurium from 3.2 X 105 colony forming units (CFU)/ml to 1.6 X 107 CFU/ml. The system was developed to utilize a fiber-optic magnetic focusing problem that attracted the magnetic microspheres to the surface of a sample chamber directly in front of the excitation and emission fibers. The signal obtained from a homogenous suspension of fluorescent magnetic microspheres was 9 to 10 picowatts. After focusing, the signal from the fluorescent labeled magnetic microspheres increased to 200 picowatts, approximately 20 times greater than the homogeneous suspension. The magnetic focusing assay detected 1.59 X 105 colony forming units/ml of Salmonella typhimurium cultured in growth media. The process of magnetic focusing in front of the fibers has the potential to reduce the background fluorescence from unbound secondary antibodies, eliminating several rinsing steps, resulting in a simple rapid assay.

  16. 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. PMID:25895967

  17. Novel Salmonella enterica serovar Typhimurium protein that is indispensable for virulence and intracellular replication.

    PubMed

    van der Straaten, T; van Diepen, A; Kwappenberg, K; van Voorden, S; Franken, K; Janssen, R; Kusters, J G; Granger, D L; van Dissel, J T

    2001-12-01

    Upon contact with host cells, the intracellular pathogen Salmonella enterica serovar Typhimurium promotes its uptake, targeting, and survival in intracellular niches. In this process, the bacterium evades the microbicidal effector mechanisms of the macrophage, including oxygen intermediates. This study reports the phenotypic and genotypic characterization of an S. enterica serovar Typhimurium mutant that is hypersusceptible to superoxide. The susceptible phenotype is due to a MudJ insertion-inactivation of a previously undescribed Salmonella gene designated sspJ that is located between 54.4 and 64 min of the Salmonella chromosome and encodes a 392-amino-acid protein. In vivo, upon intraperitoneal injection of 10(4) to 10(7) bacteria in C3H/HeN and 10(1) to 10(4) bacteria in BALB/c mice, the mutant strain was less virulent than the wild type. Consistent with this finding, during the first hour after ingestion by macrophage-like J774 and RAW264.7 cells in vitro, the intracellular killing of the strain carrying sspJ::MudJ is enhanced fivefold over that of wild-type microorganisms. Wild-type salmonellae displayed significant intracellular replication during the first 24 h after uptake, but sspJ::MudJ mutants failed to do so. This phenotype could be restored to that of the wild type by sspJ complementation. The SspJ protein is found in the cytoplasmic membrane and periplasmic space. Amino acid sequence homology analysis did reveal a leader sequence and putative pyrroloquinoline quinone-binding domains, but no putative protein function. We excluded the possibility that SspJ is a scavenger of superoxide or has superoxide dismutase activity. PMID:11705915

  18. 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

  19. Characterization of Salmonella enterica serovar Typhimurium and Salmonella enterica serovar 4,[5],12:i:- isolates from pigs presenting with diarrhea in Korea

    PubMed Central

    LEE, Ki-Eun; LEE, Deog-Yong; CHOI, Hwan-Won; CHAE, Su-Jin; YUN, Young-Sun; LEE, Ki-Chan; CHO, Yun-Sang; YANG, Dong-Kun

    2015-01-01

    Between 2011 and 2012, a total of 896 pig fecal samples were collected from nine provinces in Korea, and 50 salmonella enterica susp. enterica serovar Typhimurium (S. Typhimurium) was isolated. The characteristics of the 50 strains were analyzed, and 4 strains were identified as Salmonella enterica subsp. enterica serovar 4,[5],12:i:-. Salmonella 4,[5],12:i:- could not be distinguished from S. Typhimurium through phage typing, antimicrobial resistance testing or multiple-locus variable-number tandem repeat analysis (MLVA). However, among the four Salmonella 4,[5],12:i:- strains, one (KVCC-BA1400078) was identified as a Salmonella 4,[5],12:i:- clone isolated from humans in the United States, and another (KVCC-BA1400080) was identified as DT193, which has been primarily isolated from humans and animals in European countries. The presence of Salmonella 4,[5],12:i:- in Korea poses a significant threat of horizontal transfer between pigs and humans. PMID:26074410

  20. Inverse agonist of estrogen-related receptor γ controls Salmonella typhimurium infection by modulating host iron homeostasis.

    PubMed

    Kim, Don-Kyu; Jeong, Jae-Ho; Lee, Ji-Min; Kim, Kwang Soo; Park, Seung-Hwan; Kim, Yong Deuk; Koh, Minseob; Shin, Minsang; Jung, Yoon Seok; Kim, Hyung-Seok; Lee, Tae-Hoon; Oh, Byung-Chul; Kim, Jae Il; Park, Hwan Tae; Jeong, Won-Il; Lee, Chul-Ho; Park, Seung Bum; Min, Jung-Joon; Jung, Sook-In; Choi, Seok-Yong; Choy, Hyon E; Choi, Hueng-Sik

    2014-04-01

    In response to microbial infection, expression of the defensin-like peptide hepcidin (encoded by Hamp) is induced in hepatocytes to decrease iron release from macrophages. To elucidate the mechanism by which Salmonella enterica var. Typhimurium (S. typhimurium), an intramacrophage bacterium, alters host iron metabolism for its own survival, we examined the role of nuclear receptor family members belonging to the NR3B subfamily in mouse hepatocytes. Here, we report that estrogen-related receptor γ (ERRγ, encoded by Esrrg) modulates the intramacrophage proliferation of S. typhimurium by altering host iron homeostasis, and we demonstrate an antimicrobial effect of an ERRγ inverse agonist. Hepatic ERRγ expression was induced by S. typhimurium-stimulated interleukin-6 signaling, resulting in an induction of hepcidin and eventual hypoferremia in mice. Conversely, ablation of ERRγ mRNA expression in liver attenuated the S. typhimurium-mediated induction of hepcidin and normalized the hypoferremia caused by S. typhimurium infection. An inverse agonist of ERRγ ameliorated S. typhimurium-mediated hypoferremia through reduction of ERRγ-mediated hepcidin mRNA expression and exerted a potent antimicrobial effect on the S. typhimurium infection, thereby improving host survival. Taken together, these findings suggest an alternative approach to control multidrug-resistant intracellular bacteria by modulating host iron homeostasis. PMID:24658075

  1. Multiple antibiotic resistance (mar) locus in Salmonella enterica serovar typhimurium DT104.

    PubMed

    Randall, L P; Woodward, M J

    2001-03-01

    In order to understand the role of the mar locus in Salmonella with regard to multiple antibiotic resistance, cyclohexane resistance, and outer membrane protein F (OmpF) regulation, a marA::gfp reporter mutant was constructed in an antibiotic-sensitive Salmonella enterica serovar Typhimurium DT104 background. Salicylate induced marA, whereas a number of antibiotics, disinfectants, and various growth conditions did not. Increased antibiotic resistance was observed upon salicylate induction, although this was shown to be by both mar-dependent and mar-independent pathways. Cyclohexane resistance, however, was induced by salicylate by a mar-dependent pathway. Complementation studies with a plasmid that constitutively expressed marA confirmed the involvement of mar in Salmonella with low-level antibiotic resistance and cyclohexane resistance, although the involvement of mar in down regulation of OmpF was unclear. However, marA overexpression did increase the expression of a ca. 50-kDa protein, but its identity remains to be elucidated. Passage of the marA::gfp reporter mutant with increasing levels of tetracycline, a method reported to select for mar mutants in Escherichia coli, led to both multiple-antibiotic and cyclohexane resistance. Collectively, these data indicate that low-level antibiotic resistance, cyclohexane resistance, and modulation of OMPs in Salmonella, as in E. coli, can occur in both a mar-dependent and mar-independent manner. PMID:11229910

  2. Salmonella enterica Serovar Typhimurium Skills To Succeed in the Host: Virulence and Regulation

    PubMed Central

    Fàbrega, Anna

    2013-01-01

    SUMMARY Salmonella enterica serovar Typhimurium is a primary enteric pathogen infecting both humans and animals. Infection begins with the ingestion of contaminated food or water so that salmonellae reach the intestinal epithelium and trigger gastrointestinal disease. In some patients the infection spreads upon invasion of the intestinal epithelium, internalization within phagocytes, and subsequent dissemination. In that case, antimicrobial therapy, based on fluoroquinolones and expanded-spectrum cephalosporins as the current drugs of choice, is indicated. To accomplish the pathogenic process, the Salmonella chromosome comprises several virulence mechanisms. The most important virulence genes are those located within the so-called Salmonella pathogenicity islands (SPIs). Thus far, five SPIs have been reported to have a major contribution to pathogenesis. Nonetheless, further virulence traits, such as the pSLT virulence plasmid, adhesins, flagella, and biofilm-related proteins, also contribute to success within the host. Several regulatory mechanisms which synchronize all these elements in order to guarantee bacterial survival have been described. These mechanisms govern the transitions from the different pathogenic stages and drive the pathogen to achieve maximal efficiency inside the host. This review focuses primarily on the virulence armamentarium of this pathogen and the extremely complicated regulatory network controlling its success. PMID:23554419

  3. Retinoic acid decreases the severity of Salmonella enterica serovar Typhimurium mediated gastroenteritis in a mouse model.

    PubMed

    Sinha, Ritam; Howlader, Debaki Ranjan; Mukherjee, Priyadarshini; Rai, Sulabh; Nag, Dhrubajyoti; Koley, Hemanta

    2016-07-01

    Gastroenteritis is a global burden; it's the major cause of morbidity and mortality both in adults and children of developing countries. Salmonella is one of the leading causes of bacteria-mediated gastroenteritis and due to its increasing multidrug antibiotic resistance; Salmonella-mediated gastroenteritis is difficult to control. Retinoic acid, the biologically active agent of vitamin A has an anti-inflammatory effect on experimental colitis. In this study we have shown All trans retinoic acid (ATRA) treatment down regulates Salmonella-mediated colitis in a murine model. Macroscopic signs of inflammation such as decrease in body weight and cecum weight, shorter length of proximal colon and pathological score of colitis were observed less in ATRA treated mice than in a vehicle control group. ATRA treatment not only reduced pro-inflammatory cytokine responses, such as TNF-α, IL-6, IL-1β, IFN-γ and IL-17 production but also increased IL-10 response in the supernatant of intestinal tissue. Results also suggested that ATRA treatment enhances the number of FoxP3-expressing T regulatory cells in MLN and also decreases bacterial load in systemic organs. We concluded that ATRA treatment indeed reduces Salmonella Typhimurium-mediated gastroenteritis in mice, suggesting it could be an important part of an alternative therapeutic approach to combat the disease. PMID:26858186

  4. 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. PMID:27357046

  5. 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.; Vanderburg, C. R.; Hammond, T.; Pierson, D. 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 1alpha (IL-1alpha), IL-1beta, 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 beta1 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.

  6. Identification of tumor-specific Salmonella Typhimurium promoters and their regulatory logic

    PubMed Central

    Leschner, Sara; Deyneko, Igor V.; Lienenklaus, Stefan; Wolf, Kathrin; Bloecker, Helmut; Bumann, Dirk; Loessner, Holger; Weiss, Siegfried

    2012-01-01

    Conventional cancer therapies are often limited in effectiveness and exhibit strong side effects. Therefore, alternative therapeutic strategies are demanded. The employment of tumor-colonizing bacteria that exert anticancer effects is such a novel approach that attracts increasing attention. For instance, Salmonella enterica serovar Typhimurium has been used in many animal tumor models as well as in first clinical studies. These bacteria exhibit inherent tumoricidal effects. In addition, they can be used to deliver therapeutic agents. However, bacterial expression has to be restricted to the tumor to prevent toxic substances from harming healthy tissue. Therefore, we screened an S. Typhimurium promoter-trap library to identify promoters that exclusively drive gene expression in the cancerous tissue. Twelve elements could be detected that show reporter gene expression in tumors but not in spleen and liver. In addition, a DNA motif was identified that appears to be necessary for tumor specificity. Now, such tumor-specific promoters can be used to safely express therapeutic proteins by tumor-colonizing S. Typhimurium directly in the neoplasia. PMID:22140114

  7. Effects of temperature abuse on the survival, growth, and inactivation of Salmonella typhimurium in goat milk.

    PubMed

    Migeemanathan, Suguna; Bhat, Rajeev; Min-Tze, Liong; Wan-Abdullah, Wan-Nadiah

    2011-11-01

    The growth and survival of Salmonella typhimurium in goat milk samples at different shifting temperatures were evaluated. The growth of S. typhimurium at lower temperatures (5°C, 10°C, and 15°C) exhibited bacteriostatic effects in milk, whereas at ambient temperature (25°C) and at 45°C, this pathogen luxuriantly grew throughout the 12-h stationary phase. At 50°C this pathogen was found to be thermotolerant and could still thrive in the milk. Overall, shifting temperatures from 37°C to 55°C and 60°C clearly indicated S. typhimurium to have reached complete elimination. The results demonstrated that the adaptation and survival of this pathogen directly depend on temperature stress. It is expected that the results will be useful to dairy industries for implementation of good manufacturing practices with a better hazard analysis critical control point approach to predict the microbial risk assessment and also benefit the consumers. PMID:21819211

  8. 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. PMID:26260191

  9. Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with Salmonella enterica serovar Typhimurium

    PubMed Central

    Laughlin, Richard C.; Knodler, Leigh A.; Barhoumi, Roula; Payne, H. Ross; Wu, Jing; Gomez, Gabriel; Pugh, Roberta; Lawhon, Sara D.; Bäumler, Andreas J.; Steele-Mortimer, Olivia; Adams, L. Garry

    2014-01-01

    ABSTRACT To establish a replicative niche during its infectious cycle between the intestinal lumen and tissue, the enteric pathogen Salmonella enterica serovar Typhimurium requires numerous virulence genes, including genes for two type III secretion systems (T3SS) and their cognate effectors. To better understand the host-pathogen relationship, including early infection dynamics and induction kinetics of the bacterial virulence program in the context of a natural host, we monitored the subcellular localization and temporal expression of T3SS-1 and T3SS-2 using fluorescent single-cell reporters in a bovine, ligated ileal loop model of infection. We observed that the majority of bacteria at 2 h postinfection are flagellated, express T3SS-1 but not T3SS-2, and are associated with the epithelium or with extruding enterocytes. In epithelial cells, S. Typhimurium cells were surrounded by intact vacuolar membranes or present within membrane-compromised vacuoles that typically contained numerous vesicular structures. By 8 h postinfection, T3SS-2-expressing bacteria were detected in the lamina propria and in the underlying mucosa, while T3SS-1-expressing bacteria were in the lumen. Our work identifies for the first time the temporal and spatial regulation of T3SS-1 and -2 expression during an enteric infection in a natural host and provides further support for the concept of cytosolic S. Typhimurium in extruding epithelium as a mechanism for reseeding the lumen. PMID:24496791

  10. Molecular cloning and expression of the ilvGEDAY genes from Salmonella typhimurium.

    PubMed

    Blazey, D L; Kim, R; Burns, R O

    1981-08-01

    The ilvGEDAY genes of Salmonella typhimurium were cloned in Escherichia coli K-12 by in vitro recombination techniques. A single species of recombinant plasmid, designated pDU1, was obtained by selecting for Valr Ampr transformants of strain SK1592. pDU1 was shown to contain a 14-kilobase EcoRI partial digestion product of the S. typhimurium chromosome inserted into the EcoRI site of the pVH2124 cloning vector. The ilvGEDAY genes were found to occupy a maximum length of 7.5 kilobases. Restriction endonuclease analysis of the S. typhimurium ilv gene cluster provided another demonstration of the gene order as well as established the location of ilv Y between ilvA and ilvC. The presence of a ribosomal ribonucleic acid operon on the pDU1 insert, about 3 kilobases from the 5' end of ilvG, was shown by Southern hybridization. The expression of the ilvGEDA operon from pDU1 was found to be elevated, reflecting the increased gene dosage of the multicopy plasmid. A polarity was observed with respect to ilvEDA expression which is discussed in terms of the possible translational effects of the two internal promoter sequences, one located proximal to ilvE and the other located proximal to ilvD. PMID:6167564

  11. 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

  12. Salmonella enterica serovar Typhimurium-induced placental inflammation and not bacterial burden correlates with pathology and fatal maternal disease.

    PubMed

    Chattopadhyay, Anindita; Robinson, Nirmal; Sandhu, Jagdeep K; Finlay, B Brett; Sad, Subash; Krishnan, Lakshmi

    2010-05-01

    Food-borne infections caused by Salmonella enterica species are increasing globally, and pregnancy poses a high risk. Pregnant mice rapidly succumb to S. enterica serovar Typhimurium infection. To determine the mechanisms involved, we addressed the role of inflammation and bacterial burden in causing placental and systemic disease. In vitro, choriocarcinoma cells were a highly conducive niche for intracellular S. Typhimurium proliferation. While infection of mice with S. Typhimurium wild-type (WT) and mutant (Delta aroA and Delta invA) strains led to profound pathogen proliferation and massive burden within placental cells, only the virulent WT S. Typhimurium infection evoked total fetal loss and adverse host outcome. This correlated with substantial placental expression of granulocyte colony-stimulating factor (G-CSF), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) and increased serum inflammatory cytokines/chemokines, such as G-CSF, IL-6, CCL1, and KC, evoked by WT S. Typhimurium infection. In contrast, infection with high doses of S. Typhimurium Delta aroA, despite causing massive placental infection, resulted in reduced inflammatory cellular and cytokine response. While S. Typhimurium WT bacteria were dispersed in large numbers across all regions of the placenta, including the deeper labyrinth trophoblast, S. Typhimurium Delta aroA bacteria localized primarily to the decidua. This correlated with the widespread placental necrosis accompanied by neutrophil infiltration evoked by the S. Typhimurium WT bacteria. Thus, the ability of Salmonella to localize to deeper layers of the placenta and the nature of inflammation triggered by the pathogen, rather than bacterial burden, profoundly influenced placental integrity and host survival. PMID:20194592

  13. Efficiency of Conditionally Attenuated Salmonella enterica Serovar Typhimurium in Bacterium-Mediated Tumor Therapy

    PubMed Central

    Frahm, Michael; Kocijancic, Dino; Rohde, Manfred; Hensel, Michael; Curtiss, Roy; Erhardt, Marc; Weiss, Siegfried

    2015-01-01

    ABSTRACT Increasing numbers of cancer cases generate a great urge for new treatment options. Applying bacteria like Salmonella enterica serovar Typhimurium for cancer therapy represents an intensively explored option. These bacteria have been shown not only to colonize solid tumors but also to exhibit an intrinsic antitumor effect. In addition, they could serve as tumor-targeting vectors for therapeutic molecules. However, the pathogenic S. Typhimurium strains used for tumor therapy need to be attenuated for safe application. Here, lipopolysaccharide (LPS) deletion mutants (ΔrfaL, ΔrfaG, ΔrfaH, ΔrfaD, ΔrfaP, and ΔmsbB mutants) of Salmonella were investigated for efficiency in tumor therapy. Of such variants, the ΔrfaD and ΔrfaG deep rough mutants exhibited the best tumor specificity and lowest pathogenicity. However, the intrinsic antitumor effect was found to be weak. To overcome this limitation, conditional attenuation was tested by complementing the mutants with an inducible arabinose promoter. The chromosomal integration of the respective LPS biosynthesis genes into the araBAD locus exhibited the best balance of attenuation and therapeutic benefit. Thus, the present study establishes a basis for the development of an applicably cancer therapeutic bacterium. PMID:25873375

  14. Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium

    PubMed Central

    Yun, Ou; Zeng, Xin-An; Brennan, Charles S.; Han, Zhong

    2016-01-01

    Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0–4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms. PMID:27556460

  15. Mutagenicity evaluation of phthalic acid esters and metabolites in Salmonella typhimurium cultures

    SciTech Connect

    Agarwal, D.K.; Lawrence, W.H.; Nunez, L.J.; Autian, J.

    1985-01-01

    The mutagenic potential of dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEPH), as well as metabolites of DEHP - i.e., mono-2-ethylhexyl phthalate (MEHP), 2-ethylhexanol (2-EH), and phthalic acid (PA) - were tested in Salmonella typhimurium cultures using the Ames test procedure. The compounds were tested on strains TA98, TA100, TA1535, TA1537, TA1538, and TA2637 for base-pair substitution or frameshift-type mutations. Spot tests yielded negative responses for all compounds with the strains tested. Each compound was tested for a dose-effect relationship in the TA98, TA100, TA1535, and TA1538 systems. DEP and DBP exhibited a mildly positive response in both TA100 and TA1535 cultures, and DMP showed a similar response in TA1535. Normalization of the data for cytotoxicity of DMP suggests TA100 has a mildly positive effect. The higher doses of these compounds exhibited some cytotoxic effects. The mutagenic effects were apparently abolished by the addition of S9 fraction in TA100 and TA1535 cultures, while no effect, other than cytotoxicity, was observed in the TA98 and TA1538 systems. DEHP, MEHP, 2-EH, and PA exhibited no mutagenicity in any of the strains of Salmonella, typhimurium tested, with or without S9 metabolic activation. MEHP and 2-EH, however, exhibited a moderate cytotoxic effect in most cultures.

  16. Cell-Mediated Resistance Induced with Immunogenic Preparations of Salmonella typhimurium

    PubMed Central

    Venneman, Martin R.; Berry, L. Joe

    1971-01-01

    Peritoneal cells obtained from mice immunized 15 or 30 days previously with (i) 0.1 LD50 of attenuated Salmonella typhimurium (RIA), (ii) 20 μg (dry weight) of heat-killed Salmonella (SR-11), (iii) 20 μg (dry weight) of immunogenic ribosomal subfractions, or (iv) 20 μg of ribonucleic acid (RNA) subfractions were passively transferred to normal unimmunized mice. The ability of the recipient animals to inhibit or retard the multiplication of virulent challenge S. typhimurium 5 days post-infection was determined by pathogen counts on the carcasses. Peritoneal cells from donors immunized with the RIA, ribosomal, or RNA preparations (i) conferred maximal resistance to challenge 10 to 15 days after cell transfer and demonstrable resistance throughout the 45-day assay period, (ii) conferred resistance to infection when 105, 103, or 102 peritoneal cells were injected subcutaneously but not with fewer than 105 cells administered intraperitoneally, and (iii) rendered recipients capable of acting as donors of peritoneal cells that conferred demonstrable resistance on normal recipients. Recipients of peritoneal cells obtained from donors immunized with heat-killed bacteria were unable to (i) significantly inhibit bacterial proliferation at 10 days post-transfer, (ii) resist infection by a challenge inoculum greater than 50 LD50, and (iii) secondarily confer resistance on normal animals through the passive transfer of cells or serum. PMID:4949498

  17. Salmonella typhimurium DT104: a virulent and drug-resistant pathogen.

    PubMed Central

    Poppe, C; Smart, N; Khakhria, R; Johnson, W; Spika, J; Prescott, J

    1998-01-01

    Salmonella typhimurium phage type (PT) or definitive type (DT) 104 is a virulent pathogen for humans and animals, particularly cattle. It has been isolated increasingly from humans and animals in the United Kingdom and several other European countries and, more recently, in the United States and Canada. Humans may acquire the infection from foods of animal origin contaminated with the infective organism. Farm families are particularly at risk of acquiring the infection by contact with infected animals or by drinking unpasteurized milk. The symptoms in cattle are watery to bloody diarrhea, a drop in milk production, pyrexia, anorexia, dehydration and depression. Infection may result in septicemic salmonellosis and, upon necropsy, a fibrinonecrotic enterocolitis may be observed. The infection occurs more commonly in the calving season than at other times. Feedlot cattle and pigs may also be affected. Prolonged carriage and shedding of the pathogen may occur. Symptoms in humans consist of diarrhea, fever, headache, nausea, abdominal pain, vomiting, and, less frequently, blood in the stool. Salmonella typhimurium DT104 strains are commonly resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline. PMID:9752592

  18. A method for investigating protein-protein interactions related to Salmonella typhimurium pathogenesis

    SciTech Connect

    Chowdhury, Saiful M.; Shi, Liang; Yoon, Hyunjin; Ansong, Charles; Rommereim, Leah M.; Norbeck, Angela D.; Auberry, Kenneth J.; Moore, R. J.; Adkins, Joshua N.; Heffron, Fred; Smith, Richard D.

    2009-02-10

    We successfully modified an existing method to investigate protein-protein interactions in the pathogenic bacterium Salmonella typhimurium (STM). This method includes i) addition of a histidine-biotin-histidine tag to the bait proteins via recombinant DNA techniques; ii) in vivo cross-linking with formaldehyde; iii) tandem affinity purification of bait proteins under fully denaturing conditions; and iv) identification of the proteins cross-linked to the bait proteins by liquid-chromatography in conjunction with tandem mass-spectrometry. In vivo cross-linking stabilized protein interactions permitted the subsequent two-step purification step conducted under denaturing conditions. The two-step purification greatly reduced nonspecific binding of non-cross-linked proteins to bait proteins. Two different negative controls were employed to reduce false-positive identification. In an initial demonstration of this approach, we tagged three selected STM proteins- HimD, PduB and PhoP- with known binding partners that ranged from stable (e.g., HimD) to transient (i.e., PhoP). Distinct sets of interacting proteins were identified with each bait protein, including the known binding partners such as HimA for HimD, as well as anticipated and unexpected binding partners. Our results suggest that novel protein-protein interactions may be critical to pathogenesis by Salmonella typhimurium. .

  19. Structural basis for the mechanism of inhibition of uridine phosphorylase from Salmonella typhimurium

    SciTech Connect

    Lashkov, A. A.; Zhukhlistova, N. E.; Sotnichenko, S. E.; Gabdulkhakov, A. G.; Mikhailov, A. M.

    2010-01-15

    The three-dimensional structures of three complexes of Salmonella typhimurium uridine phosphorylase with the inhibitor 2,2'-anhydrouridine, the substrate PO{sub 4}, and with both the inhibitor 2,2'-anhydrouridine and the substrate PO{sub 4} (a binary complex) were studied in detail by X-ray diffraction. The structures of the complexes were refined at 2.38, 1.5, and 1.75 A resolution, respectively. Changes in the three-dimensional structure of the subunits in different crystal structures are considered depending on the presence or absence of the inhibitor molecule and (or) the phosphate ion in the active site of the enzyme. The presence of the phosphate ion in the phosphate-binding site was found to substantially change the orientations of the side chains of the amino-acid residues Arg30, Arg91, and Arg48 coordinated to this ion. A comparison showed that the highly flexible loop L9 is unstable. The atomic coordinates of the refined structures of the complexes and the corresponding structure factors were deposited in the Protein Data Bank (their PDB ID codes are 3DD0 and 3C74). The experimental data on the spatial reorganization of the active site caused by changes in its functional state from the unligated to the completely inhibited state suggest the structural basis for the mechanism of inhibition of Salmonella typhimurium uridine phosphorylase.

  20. Cloning and nucleotide sequence of the Salmonella typhimurium dcp gene encoding dipeptidyl carboxypeptidase.

    PubMed Central

    Hamilton, S; Miller, C G

    1992-01-01

    Plasmids carrying the Salmonella typhimurium dcp gene were isolated from a pBR328 library of Salmonella chromosomal DNA by screening for complementation of a peptide utilization defect conferred by a dcp mutation. Strains carrying these plasmids overproduced dipeptidyl carboxypeptidase approximately 50-fold. The nucleotide sequence of a 2.8-kb region of one of these plasmids contained an open reading frame coding for a protein of 77,269 Da, in agreement with the 80-kDa size for dipeptidyl carboxypeptidase (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration). The N-terminal amino acid sequence of dipeptidyl carboxypeptidase purified from an overproducer strain agreed with that predicted by the nucleotide sequence. Northern (RNA) blot data indicated that dcp is not cotranscribed with other genes, and primer extension analysis showed the start of transcription to be 22 bases upstream of the translational start. The amino acid sequence of dcp was not similar to that of a mammalian dipeptidyl carboxypeptidase, angiotensin I-converting enzyme, but showed striking similarities to the amino acid sequence of another S. typhimurium peptidase encoded by the opdA (formerly optA) gene. Images PMID:1537804

  1. Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium.

    PubMed

    Yun, Ou; Zeng, Xin-An; Brennan, Charles S; Han, Zhong

    2016-01-01

    Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0-4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms. PMID:27556460

  2. Identification of potential drug targets in Salmonella enterica sv. Typhimurium using metabolic modelling and experimental validation.

    PubMed

    Hartman, Hassan B; Fell, David A; Rossell, Sergio; Jensen, Peter Ruhdal; Woodward, Martin J; Thorndahl, Lotte; Jelsbak, Lotte; Olsen, John Elmerdahl; Raghunathan, Anu; Daefler, Simon; Poolman, Mark G

    2014-06-01

    Salmonella enterica sv. Typhimurium is an established model organism for Gram-negative, intracellular pathogens. Owing to the rapid spread of resistance to antibiotics among this group of pathogens, new approaches to identify suitable target proteins are required. Based on the genome sequence of S. Typhimurium and associated databases, a genome-scale metabolic model was constructed. Output was based on an experimental determination of the biomass of Salmonella when growing in glucose minimal medium. Linear programming was used to simulate variations in the energy demand while growing in glucose minimal medium. By grouping reactions with similar flux responses, a subnetwork of 34 reactions responding to this variation was identified (the catabolic core). This network was used to identify sets of one and two reactions that when removed from the genome-scale model interfered with energy and biomass generation. Eleven such sets were found to be essential for the production of biomass precursors. Experimental investigation of seven of these showed that knockouts of the associated genes resulted in attenuated growth for four pairs of reactions, whilst three single reactions were shown to be essential for growth. PMID:24777662

  3. transcriptional response of pigs to Salmonella infection: Comparison of responses to infection with Salmonella eimerica serotype Typhimurium as that observed in S. choleraesuis infection.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swine responses to, and control of, Salmonella enterica serotype Typhimurium (ST) infection have been compared to S. enterica serotype Choleraesuis (SC) infection. Using subtractive suppression hybridization (SSH), long oligonucleotide Qiagen and Affymetrix porcine GeneChip® arrays, and real time ge...

  4. Assessment of altered binding specificity of bacteriophage for ciprofloxacin-induced antibiotic-resistant Salmonella Typhimurium.

    PubMed

    Kim, Jeongjin; Jo, Ara; Ding, Tian; Lee, Hyeon-Yong; Ahn, Juhee

    2016-08-01

    This study describes a new effort toward understanding the interaction mechanisms between antibiotic-resistant Salmonella Typhimurium and phages. The antibiotic susceptibility, β-lactamase activity, bacterial motility, gene expression, and lytic activity were evaluated in ciprofloxacin-induced antibiotic-sensitive Salmonella Typhimurium (ASST(CIP)) and ciprofloxacin-induced antibiotic-resistant S. Typhimurium (ARST(CIP)), which were compared to the wild-type strains (ASST(WT) and ARST(WT)). The MIC values of ampicillin, norfloxacin, chloramphenicol, and tetracycline were significantly increased to > 512, 16, 16, and 256 μg/ml, respectively, in the ARST(CIP). The lowest and highest extracellular lactamase activities were observed in ASST(WT) (6.85 μmol/min/ml) and ARST(CIP) (48.83 μmol/min/ml), respectively. The acrA, lpfE, and hilA genes were significantly upregulated by more than tenfold in both ASST(CIP) and ARST(CIP). The induction of multiple antibiotic resistance resulted from the increased efflux pump activity (AcrAB-TolC). The highest phage adsorption rates were more than 95 % for ASST(WT), ASST(CIP), and ARST(WT), while the lowest adsorption rate was 52 % for ARST(CIP) at 15 min of infection. The least lytic activity of phage was 20 % against the ARST(CIP), followed by ASST(CIP) (30 %). The adsorption rate of phage against ARST(CIP) was 52 % at 15 min of infection, which resulted in the decrease in lytic activity (12 %). Understanding the interaction of phage and bacteria is essential for the practical application of phage to control and detect antibiotic-resistant bacteria. The results provide useful information for understanding the binding specificity of phages for multiple antibiotic-resistant pathogens. PMID:27000396

  5. Use of Glycerol as an Optical Clearing Agent for Enhancing Photonic Transference and Detection of Salmonella typhimurium Through Porcine Skin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate glycerol (GLY) and GLY + dimethyl sulfoxide (DMSO) to increase photonic detection of transformed Salmonella typhimurium (S. typh-lux) through porcine skin. Skin was placed on 96-well plates containing S. typh-lux, imaged (5 min) using a CCD camera, and the...

  6. USE OF GLYCEROL AS AN OPTICAL CLEARING AGENT FOR ENHANCING PHOTONIC TRANSFERENCE AND DETECTIONOF SALMONELLA TYPHIMURIUM THROUGH PORCINE SKIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate glycerol (GLY) and GLY+DMSO (dimethyl sulfoxide) to increase photonic detection of transformed Salmonella typhimurium (S.typh-Lux) through porcineskin. A 96-well plate containing S. typh-lux was imaged for 5 min as a control reference usinga CCD camera. Sk...

  7. Use of Glycerol as an Optical Clearing Agent for Enhancing Photonic Transference and Detection of Salmonella typhimurium through Porcine Skin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate glycerol (GLY) and GLY + dimethyl sulfoxide (DMSO) to increase photonic detection of transformed Salmonella typhimurium (S. typh-lux) through porcine skin. Skin was placed on 96-well plates containing S. typh-lux, imaged (5 min) using a CCD camera, and the...

  8. Interaction of Bifidobacterium animalis subspecies lactis (Bb 12) and Salmonella typhimurium in continuous-flow chemostatic culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A commercially available probiotic, Bifidobacterium animalis subspecies lactis (Bb12) was adapted to and maintained in a continuous-flow chemostat culture. We evaluated the growth characteristics and interactive effects of Bb12 and a porcine-derived Salmonella typhimurium (St) when cultivated singly...

  9. CORRELATION BETWEEN BENZO(A)PYRENE-INDUCED MUTAGENICITY AND DNA ADDUCT FORMATION IN 'SALMONELLA TYPHIMURIUM' TA100

    EPA Science Inventory

    In an attempt to stabilize the dose response in the Salmonella typhimurium test (STT), the use of DNA-bound products from BP was evaluated as a measure of the biologically effective dose. In addition to the previously documented interlaboratory variation, the authors observed a 3...

  10. Contaminated Larval and Adult Lesser Mealworms, Alphitobius diaperinus (Coleoptera: Tenebrionidae)can Transmit Salmonella Typhimurium in a Broiler Flock

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of the lesser mealworm, Alphitobius diaperinus (Panzer), commonly known as the darkling beetle, to transmit a marker strain Salmonella Typhimurium to day-of-hatch broiler chicks was evaluated, as well as the spread to non-challenged pen mates. Day-of-hatch chicks were orally gavaged wit...

  11. Inactivation of Salmonella enterica serovar Typhimurium and quality maintenance of cherry tomatoes treated with gaseous essential oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The antimicrobial activity of the essential oils (EOs) from cinnamon bark, oregano, mustard and of their major components cinnamaldehyde, carvacrol, and allyl isothiocyanate (AIT) were evaluated as a gaseous treatment to reduce Salmonella enterica serovar Typhimurium in vitro and on tomatoes. In dif...

  12. Evaluation of Photonic Imaging in the Gastrointestinal Tract of Swine Following Oral Inoculation With Lux-Modified Salmonella typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to evaluate photonic emitting bacteria through different segments of the gastrointestinal tract of swine. Pigs (~ 80 kg) were inoculated orally with 3.1 or 4.1×10^10 CFU of Salmonella typhimurium transformed with plasmid pAK1-lux (S. typh-lux) for a 6 (n=6) or 12 (n=6) h incubatio...

  13. Interaction of Bifidobacterium animalis subspecies lactis (Bb12) and Salmonella typhimurium in continuous-flow chemostatic culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A commercially available probiotic, Bifidobacterium animalis subspecies lactis (Bb12) was adapted to and maintained in a continuous-flow chemostat culture. We evaluated the growth characteristics and in interactive effects of Bb12 and a porcine-derived Salmonella typhimurium (St) when cultivated si...

  14. Effect of Age on Susceptibility to Salmonella typhimurium Infection in C57BL/6 Mice: Role of the Immune System

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aging is associated with a decline in immune function, which predisposes the elderly to higher incidence of infections. Enterocolitis caused by Salmonella typhimurium (ST) infection is a common foodborne disease in the US. However, information on the mechanism of age-related increase in susceptibili...

  15. Molecular profiling: Catecholamine modulation of gene expression in Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Investigations of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium have demonstrated that these bacterial pathogens can respond to the presence of catecholamines including norepinephrine and/or epinephrine in their environment by modulating gene expression and exhibiting various ...

  16. A mutation in the pnp gene encoding polynucleotide phosphorylase attenuates virulence of Salmonella enterica serovar typhimurium in swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: 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 ...

  17. Salmonella enterica Typhimurium infection causes metabolic changes in chicken muscle involving AMPK, fatty acid and insulin/mTOR signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella enterica serovar Typhimurium (ST) infection of chickens more than a few days old results in asymptomatic cecal colonization with persistent shedding of bacteria. We hypothesized that while the bacteria colonize and persist locally in the cecum, it has systemic effects influencing the phy...

  18. Motility revertants of opgGH mutants of Salmonella enterica serovar Typhimurium remain defective in mice virulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We recently demonstrated that osmoregulated periplasmic glucans (OPGs) of Salmonella enterica serovar Typhimurium are required for optimal mouse virulence (Bhagwat et al., 2009. Microbiology 155:229-237). However, lack of OPGs also generated pleiotropic phenotypes such as reduced motility and slower...

  19. Age Increases Susceptibility to Salmonella typhimurium Infection in C57BL/6 Mice: Role of the Immune System

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aging is associated with a decline in immune function, which predisposes the elderly to higher incidence of infections. Enterocolitis caused by Salmonella typhimurium (ST) infection is one of the most common foodborne diseases in US. We used streptomycin-pretreated C57BL mice infected with ST to stu...

  20. Transport of Escherichia coli O157:H7 and Salmonella typhimurium in biochar-amended soils with different textures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar amendment has been shown to affect bacterial transport in soils. The effect of soil texture on the transport of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in soils amended with 2 % poultry litter or pine chip biochars pyrolyzed under two temperatures (350 and 700 'C...

  1. MOLECULAR ANALYSIS OF MUTATIONS INDUCED BY THE INTERCALATING AGENT ELLIPTICINE AT THE HISD3052 ALLELE OF SALMONELLA TYPHIMURIUM TA98

    EPA Science Inventory

    We have used colony hybridization, PCR, and direct DNA sequencing to determine the mutations induced by the intercalating agent ellipticine in Salmonella typhimurium TA98 in the presence of $9. Of 400 ellipticine-induced revertants that were selected at a mutant yield that was 9-...

  2. Diagnosis of an outbreak of Salmonella typhimurium in chinchillas (Chinchilla lanigera) by pulsed-field gel electrophoresis.

    PubMed

    Gornatti Churria, Carlos D; Vigo, Germán B; Origlia, Javier; Campos, Josefina; Caffer, María; Píscopo, Miguel; Herrero Loyola, Miguel; Petruccelli, Miguel; Pichel, Mariana

    2014-01-01

    Adult chinchillas (Chinchilla lanigera) that had suddenly died in a commercial farm located in La Plata City, Buenos Aires Province, Argentina, in July 2012 were macroscopically, histopathologically, and microbiologically examined. Salmonella enterica serovar Typhimurium (S. Typhimurium) was isolated from the liver, spleen, heart, lungs, kidneys and intestines from each of the five animals evaluated. The five strains were susceptible to ampicillin, cephalotin, cefotaxime, nalidixic acid, gentamicin, streptomycin, chloramphenicol, fosfomycin, nitrofurantoin and trimethoprim-sulfamethoxazole, and resistant to tetracycline. Each of the five S. Typhimurium isolates was analyzed by XbaI- pulsed-field gel electrophoresis (PFGE), showing an identical electrophoretic profile with 15 defined bands, which was found to be identical to pattern ARJPXX01.0220 of the PulseNet Argentine National database of Salmonella PFGE patterns. This is the first work describing the postmortem diagnosis of an outbreak of salmonellosis in chinchillas by using molecular methods such as PFGE. PMID:25444129

  3. Immunogenicity and Cross-Protective Efficacy Induced by Outer Membrane Proteins from Salmonella Typhimurium Mutants with Truncated LPS in Mice

    PubMed Central

    Liu, Qiong; Liu, Qing; Zhao, Xinxin; Liu, Tian; Yi, Jie; Liang, Kang; Kong, Qingke

    2016-01-01

    Lipopolysaccharide (LPS) is a major virulence factor present in the outer membrane of Salmonella enterica serovar Typhimurium (S. Typhimurium). Outer membrane proteins (OMPs) from Salmonella show high immunogenicity and provide protection against Salmonella infection, and truncated LPS alters the outer membrane composition of the cell wall. In our previous study, we demonstrated that Salmonella mutants carrying truncated LPS failed to induce strong immune responses and cross-reaction to other enteric bacteria, due to their high attenuation and low colonization in the host. Therefore, we plan to investigate whether outer membrane proteins from Salmonella mutants with truncated LPS resulting from a series of nonpolar mutations, including ∆waaC12, ∆waaF15, ∆waaG42, ∆rfaH49, ∆waaI43, ∆waaJ44, ∆waaL46, ∆wbaP45 and ∆wzy-48, affect immunogenicity and provide protection against diverse Salmonella challenge. In this study, the immunogenicity and cross-protection efficiency of purified OMPs from all mutants were investigated to explore a potential OMP vaccine to protect against homologous or heterologous serotype Salmonella challenge. The results demonstrated that OMPs from three Salmonella mutants (∆waaC12, ∆waaJ44 and ∆waaL46) induced higher immune responses and provided good protection against homologous S. Typhimurium. The OMPs from these three mutants were also selected to determine the cross-protective efficacy against homologous and heterologous serotype Salmonella. Our results indicated that the mutant ∆waaC12 can elicit higher cross-reactivity and can provide good protection against S. Choleraesuis and S. Enteritidis infection and that the cross-reactivity may be ascribed to an antigen of approximately 18.4–30 kDa. PMID:27011167

  4. Comparative analysis of extreme acid survival in Salmonella typhimurium, Shigella flexneri, and Escherichia coli.

    PubMed Central

    Lin, J; Lee, I S; Frey, J; Slonczewski, J L; Foster, J W

    1995-01-01

    Several members of the family Enterobacteriaceae were examined for differences in extreme acid survival strategies. A surprising degree of variety was found between three related genera. The minimum growth pH of Salmonella typhimurium was shown to be significantly lower (pH 4.0) than that of either Escherichia coli (pH 4.4) or Shigella flexneri (pH 4.8), yet E. coli and S. flexneri both survive exposure to lower pH levels (2 to 2.5) than S. typhimurium (pH 3.0) in complex medium. S. typhimurium and E. coli but not S. flexneri expressed low-pH-inducible log-phase and stationary-phase acid tolerance response (ATR) systems that function in minimal or complex medium to protect cells to pH 3.0. All of the organisms also expressed a pH-independent general stress resistance system that contributed to acid survival during stationary phase. E. coli and S. flexneri possessed several acid survival systems (termed acid resistance [AR]) that were not demonstrable in S. typhimurium. These additional AR systems protected cells to pH 2.5 and below but required supplementation of minimal medium for either induction or function. One acid-inducible AR system required oxidative growth in complex medium for expression but successfully protected cells to pH 2.5 in unsupplemented minimal medium, while two other AR systems important for fermentatively grown cells required the addition of either glutamate or arginine during pH 2.5 acid challenge. The arginine AR system was only observed in E. coli and required stationary-phase induction in acidified complex medium. The product of the adi locus, arginine decarboxylase, was responsible for arginine-based acid survival. PMID:7608084

  5. [Typing of extended-spectrum beta-lactamase-producing Salmonella typhimurium strains isolated in a pediatric unit].

    PubMed

    Mhand, R A; Soukri, A; Amarouch, H; Mdaghri, N E; Benbachir, M

    1999-01-01

    Extended-spectrum b-lactamases (ESBLs) derive mainly from TEM and SHV b-lactamases. These enzymes confer resistance to all oxyimino cephalosporins and monobactams except cephamycins and carbapems. ESBLs are often encoded by large plasmids that carry resistance determinants to multiple antibiotics and spread among the members of the Enterobacteriaceae. Since the first outbreak of Klebsiella pneumoniae expressing an extended-spectrum beta-lactamase reported in 1984, nosocomial infections due to Enterobacteriaceae species which produce ESBLs have been generally recovered from patients hospitalized in intensive care units. The most frequently isolated ESBL-producing strains belong to the genus Klebsiella, Escherichia, Enterobacter and Proteus; ESBLs are rarely associated with the genus Salmonella. The first Salmonella were detected in France in 1984 (Salmonella typhimurium), in Tunisia in 1988 (Salmonella wien) and in Argentina in 1991 (Salmonella typhimurium). In 1994, 10 isolates of Salmonella typhimurium expressing an extended-spectrum beta-lactamase were isolated for the first time from 10 children hospitalized in a pediatric unit of the hospital Ibn-Rochd, Casablanca. Previous study showed that all isolates belonged the same serotype, and biotype, and showed a resistance to oxyimino beta-lactams, gentamycin, tobramycin and trimethoprim-sulfamethoxazole but remained susceptible to tetracycline, chloramphenicol and quinolones. Oxyimino beta-lactams resistance determinant of all strains of Salmonella typhimurium was transferred by conjugation to Escherichia coli; Resistance to gentamycin and trimethoprim-sulfamethoxazole was also cotransferred. In this study, we characterized the relationship between all isolates by comparing plasmid profiles and patterns of proteins because there appear to be the more effective method for evaluating epidemiologic relationship between Salmonella species, and the protein profiles method has been used for many bacterial species. These

  6. 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

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

    PubMed

    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

  8. Acid environments affect biofilm formation and gene expression in isolates of Salmonella enterica Typhimurium DT104.

    PubMed

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

    2015-08-01

    The aim of this study was to examine the survival and potential virulence of biofilm-forming Salmonella Typhimurium DT104 under mild acid conditions. Salmonella Typhimurium DT104 employs an acid tolerance response (ATR) allowing it to adapt to acidic environments. The threat that these acid adapted cells pose to food safety could be enhanced if they also produce biofilms in acidic conditions. The cells were acid-adapted by culturing them in 1% glucose and their ability to form biofilms on stainless steel and on the surface of Luria Bertani (LB) broth at pH7 and pH5 was examined. Plate counts were performed to examine cell survival. RNA was isolated from cells to examine changes in the expression of genes associated with virulence, invasion, biofilm formation and global gene regulation in response to acid stress. Of the 4 isolates that were examined only one (1481) that produced a rigid biofilm in LB broth at pH7 also formed this same structure at pH5. This indicated that the lactic acid severely impeded the biofilm producing capabilities of the other isolates examined under these conditions. Isolate 1481 also had higher expression of genes associated with virulence (hilA) and invasion (invA) with a 24.34-fold and 13.68-fold increase in relative gene expression respectively at pH5 compared to pH7. Although genes associated with biofilm formation had increased expression in response to acid stress for all the isolates this only resulted in the formation of a biofilm by isolate 1481. This suggests that in addition to the range of genes associated with biofilm production at neutral pH, there are genes whose protein products specifically aid in biofilm production in acidic environments. Furthermore, it highlights the potential for the use of lactic acid for the inhibition of Salmonella biofilms. PMID:25912312

  9. Influence of subtherapeutic levels of a combination of neomycin and oxytetracycline on Salmonella typhimurium in swine, calves, and chickens.

    PubMed

    Girard, A E; English, A R; Evangelisti, D G; Lynch, J E; Solomons, I A

    1976-07-01

    Subtherapeutic levels of oxytetracycline plus neomycin in animal feeds did not bring about increases in the quantity, prevalence, or shedding of Salmonella typhimurium in swine, calves, or chickens. In fact, the medication generally reduced the proportion of animals carrying S. typhimurium. The medicated groups were fed rations containing oxytetracycline plus neomycin commencing 5 days prior to oral inoculation with S. typhimurium and continuing through a 28-day postinoculation period. Colonization of S. typhimurium occurred in all three animal species, as evidenced by clinical signs of infection and/or colony counts in feces. Only from swine and on only one occasion was a single resistant colony isolated. It is concluded that no evidence has been obtained which would implicate the continuous low-level feeding of oxytetracycline and neomycin for a 4-week period to a potential increased incidence of disease in animals or as a hazard to humans. PMID:791090

  10. 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

  11. A novel contribution of spvB to pathogenesis of Salmonella Typhimurium by inhibiting autophagy in host cells

    PubMed Central

    Chu, Yuanyuan; Gao, Song; Wang, Ting; Yan, Jing; Xu, Guangmei; Li, Yuanyuan; Niu, Hua; Huang, Rui; Wu, Shuyan

    2016-01-01

    Salmonella plasmid virulence genes (spv) are highly conserved in strains of clinically important Salmonella serovars. It is essential for Salmonella plasmid-correlated virulence, although the exact mechanism remains to be elucidated. Autophagy has been reported to play an important role in host immune responses limiting Salmonella infection. Our previous studies demonstrated that Salmonella conjugative plasmid harboring spv genes could enhance bacterial cytotoxicity by inhibiting autophagy. In the present study, we investigated whether spvB, which is one of the most important constituents of spv ORF could intervene in autophagy pathway. Murine macrophage-like cells J774A.1, human epithelial HeLa cells, and BALB/c mice infected with Salmonella Typhimurium wild type, mutant and complementary strains (carrying or free spvB or complemented only with ADP-ribosyltransferase activity of SpvB) were used in vitro and in vivo assay, respectively. To further explore the molecular mechanisms, both SpvB ectopic eukaryotic expression system and cells deficient in essential autophagy components by siRNA were generated. Results indicated that spvB could suppress autophagosome formation through its function in depolymerizing actin, and aggravate inflammatory injury of the host in response to S. Typhimurium infection. Our studies demonstrated virulence of spvB involving in inhibition of autophagic flux for the first time, which could provide novel insights into Salmonella pathogenesis, and have potential application to develop new antibacterial strategies for Salmonellosis. PMID:26811498

  12. A novel contribution of spvB to pathogenesis of Salmonella Typhimurium by inhibiting autophagy in host cells.

    PubMed

    Chu, Yuanyuan; Gao, Song; Wang, Ting; Yan, Jing; Xu, Guangmei; Li, Yuanyuan; Niu, Hua; Huang, Rui; Wu, Shuyan

    2016-02-16

    Salmonella plasmid virulence genes (spv) are highly conserved in strains of clinically important Salmonella serovars. It is essential for Salmonella plasmid-correlated virulence, although the exact mechanism remains to be elucidated. Autophagy has been reported to play an important role in host immune responses limiting Salmonella infection. Our previous studies demonstrated that Salmonella conjugative plasmid harboring spv genes could enhance bacterial cytotoxicity by inhibiting autophagy. In the present study, we investigated whether spvB, which is one of the most important constituents of spv ORF could intervene in autophagy pathway. Murine macrophage-like cells J774A.1, human epithelial HeLa cells, and BALB/c mice infected with Salmonella Typhimurium wild type, mutant and complementary strains (carrying or free spvB or complemented only with ADP-ribosyltransferase activity of SpvB) were used in vitro and in vivo assay, respectively. To further explore the molecular mechanisms, both SpvB ectopic eukaryotic expression system and cells deficient in essential autophagy components by siRNA were generated. Results indicated that spvB could suppress autophagosome formation through its function in depolymerizing actin, and aggravate inflammatory injury of the host in response to S. Typhimurium infection. Our studies demonstrated virulence of spvB involving in inhibition of autophagic flux for the first time, which could provide novel insights into Salmonella pathogenesis, and have potential application to develop new antibacterial strategies for Salmonellosis. PMID:26811498

  13. Epidemiology of plasmid-mediated quinolone resistance in salmonella enterica serovar typhimurium isolates from food-producing animals in Japan

    PubMed Central

    2010-01-01

    A total of 225 isolates of Salmonella enterica serovar Typhimurium from food-producing animals collected between 2003 and 2007 were examined for the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants, namely qnrA, qnrB, qnrC, qnrD, qnrS, qepA and aac(6')Ib-cr, in Japan. Two isolates (0.8%) of S. Typhimurium DT104 from different dairy cows on a single farm in 2006 and 2007 were found to have qnrS1 on a plasmid of approximately 9.6-kbp. None of the S. Typhimurium isolates had qnrA, qnrB, qnrC, qnrD, qepA and acc(6')-Ib-cr. Currently in Japan, the prevalence of the PMQR genes among S. Typhimurium isolates from food animals may remain low or restricted. The PFGE profile of two S. Typhimurium DT104 isolates without qnrS1 on the farm in 2005 had an identical PFGE profile to those of two S. Typhimurium DT104 isolates with qnrS1. The PFGE analysis suggested that the already existing S. Typhimurium DT104 on the farm fortuitously acquired the qnrS1 plasmid. PMID:21138594

  14. Purification of antibodies to O antigen of Salmonella Typhimurium from human serum by affinity chromatography.

    PubMed

    O'Shaughnessy, Colette M; Micoli, Francesca; Gavini, Massimiliano; Goodall, Margaret; Cobbold, Mark; Saul, Allan; Maclennan, Calman A

    2013-01-31

    Nontyphoidal Salmonellae (NTS) are a common cause of bacteraemia in children and HIV-infected adults in Sub-Saharan Africa. We have previously shown that antibodies play a key role in both bactericidal and cellular mechanisms of immunity to NTS, but found that high concentrations of antibody to Salmonella Typhimurium O antigen (OAg) in the serum of some HIV-infected African adults is associated with impaired killing of NTS. To further investigate the function of antibodies to the OAg of NTS, we developed a method to purify these antibodies from human serum by affinity chromatography. Purified Salmonella Typhimurium OAg was activated with adipic acid dihydrazide (ADH) via two different chemistries before linking to N-hydroxysuccinamide-Sepharose resin: one ADH molecule was introduced per OAg chain on its terminal 3-deoxy-D-manno-octulosonic acid sugar (OAg-ADH), or multiple ADH molecules were attached along the OAg chain after oxidation with sodium periodate (OAgoxADH). Both resulting columns worked well when tested with commercial polyclonal anti-O:4,5 antibodies from rabbit serum. Over 90% of the applied antibodies bound to the resin and 89% of these antibodies were then eluted as detected by ELISA. OAg-ADH was preferred as the method for OAg derivatisation as it does not modify the saccharide chain and can be applied to OAg from different bacteria. Both columns were able to bind OAg-specific antibodies in human serum, but antibody recovery was initially low. Different elution buffers were tested and different amounts of OAg-ADH were linked to the resin to improve the yield. Optimal recovery (51%) was obtained by loading 1mg of activated OAg per ml of resin and eluting with 0.1M glycine, 0.1M NaCl pH2.4. The column matrix could be regenerated following elution with no detectable loss in performance for over ten uses. This method offers the potential to purify antibodies to Salmonella OAg from polyclonal serum following vaccination or natural exposure to Salmonella

  15. Amino acid sequence of Salmonella typhimurium branched-chain amino acid aminotransferase.

    PubMed

    Feild, M J; Nguyen, D C; Armstrong, F B

    1989-06-13

    The complete amino acid sequence of the subunit of branched-chain amino acid aminotransferase (transaminase B, EC 2.6.1.42) of Salmonella typhimurium was determined. An Escherichia coli recombinant containing the ilvGEDAY gene cluster of Salmonella was used as the source of the hexameric enzyme. The peptide fragments used for sequencing were generated by treatment with trypsin, Staphylococcus aureus V8 protease, endoproteinase Lys-C, and cyanogen bromide. The enzyme subunit contains 308 residues and has a molecular weight of 33,920. To determine the coenzyme-binding site, the pyridoxal 5-phosphate containing enzyme was treated with tritiated sodium borohydride prior to trypsin digestion. Peptide map comparisons with an apoenzyme tryptic digest and monitoring radioactivity incorporation allowed identification of the pyridoxylated peptide, which was then isolated and sequenced. The coenzyme-binding site is the lysyl residue at position 159. The amino acid sequence of Salmonella transaminase B is 97.4% identical with that of Escherichia coli, differing in only eight amino acid positions. Sequence comparisons of transaminase B to other known aminotransferase sequences revealed limited sequence similarity (24-33%) when conserved amino acid substitutions are allowed and alignments were forced to occur on the coenzyme-binding site. PMID:2669973

  16. The RNA chaperone Hfq is essential for the virulence of Salmonella typhimurium

    PubMed Central

    Sittka, Alexandra; Pfeiffer, Verena; Tedin, Karsten; Vogel, Jörg

    2007-01-01

    The RNA chaperone, Hfq, plays a diverse role in bacterial physiology beyond its original role as a host factor required for replication of Qβ RNA bacteriophage. In this study, we show that Hfq is involved in the expression and secretion of virulence factors in the facultative intracellular pathogen, Salmonella typhimurium. A Salmonella hfq deletion strain is highly attenuated in mice after both oral and intraperitoneal infection, and shows a severe defect in invasion of epithelial cells and a growth defect in both epithelial cells and macrophages in vitro. Surprisingly, we find that these phenotypes are largely independent of the previously reported requirement of Hfq for expression of the stationary phase sigma factor, RpoS. Our results implicate Hfq as a key regulator of multiple aspects of virulence including regulation of motility and outer membrane protein (OmpD) expression in addition to invasion and intracellular growth. These pleiotropic effects are suggested to involve a network of regulatory small non-coding RNAs, placing Hfq at the centre of post-transcriptional regulation of virulence gene expression in Salmonella. In addition, the hfq mutation appears to cause a chronic activation of the RpoE-mediated envelope stress response which is likely due to a misregulation of membrane protein expression. PMID:17163975

  17. Suppression of Inflammation by Recombinant Salmonella typhimurium Harboring CCL22 MicroRNA

    PubMed Central

    Ryu, Seung Rel; Lee, Seung Seok; Chae, Yang Seok; Kim, Eun Jae; Choi, Ji Hyun; Oh, Sejin; Park, Se Ho; Choung, Ji Tae; Yoo, Young

    2012-01-01

    Atopic dermatitis (AD) is an inflammatory, chronically relapsing, puritic skin disorder. These syndromes result from multifactorial inheritance, with interaction between genetic and environmental factors. In particular, the macrophage-derived chemokine CCL22 is directly implicated in skin inflammatory reactions and its levels are significantly elevated in serum and correlated with disease severity in AD. We tested the suppression of the CCL22 gene by microRNA (miRNA) and observed the effects in mice with inflammation similar to AD. We used Salmonella as a vector to deliver miRNA. The recombinant strain of Salmonella typhimurium expressing CCL22 miRNA (ST-miRCCL22) was prepared for in vivo knockdown of CCL22. ST-miRCCL22 was orally inoculated into mice and the CCL22 gene suppressed with CCL22 miRNA in the activated lymphocytes. IgE and interleukin-4 were inhibited and interferon-γ was induced after treatments with ST-miRCCL22 and CCL22 was suppressed. Further, Th17 cells were suppressed in the atopic mice treated with ST-miRCCL22. These results suggested that suppression of the CCL22 gene using Salmonella induced anti-inflammatory effects. PMID:21823987

  18. Multistate outbreak of human Salmonella typhimurium infections associated with pet turtle exposure - United States, 2008.

    PubMed

    2010-02-26

    On September 4, 2008, the Philadelphia Department of Public Health (PDPH) and the Pennsylvania Department of Health (PADOH) notified CDC of an outbreak of possible turtle-associated human Salmonella Typhimurium infections detected by identifying strains with similar pulsed-field gel electrophoresis (PFGE) patterns in PulseNet. Turtles and other reptiles have long been recognized as sources of human Salmonella infections, and the sale or distribution of small turtles (those with carapace lengths <4 inches) has been prohibited in the United States since 1975. CDC and state and local health departments conducted a multistate investigation during September-November 2008. This report summarizes the results of that investigation, which identified 135 cases in 25 states and the District of Columbia; 45% were in children aged Salmonella awareness education at the point-of-sale), could augment federal prevention efforts. PMID:20186118

  19. Licoflavonol is an inhibitor of the type three secretion system of Salmonella enterica serovar Typhimurium.

    PubMed

    Guo, Zhixing; Li, Xiaoli; Li, Jianfang; Yang, Xuefei; Zhou, Yuan; Lu, Chunhua; Shen, Yuemao

    2016-09-01

    As an important food-borne human pathogen, Salmonella enterica serovar Typhimurium depends on its type III secretion system (T3SS) as a major virulence factor to cause disease all over the world. The T3SS secretes effector proteins to facilitate invasion into host cells. In this study, twenty prenylated flavonoids (1-20) were screened for their anti-T3SS activity, revealing that several analogs exhibited strong inhibitory effects on the secretion of Salmonella pathogenicity island 1 (SPI-1)-associated effector proteins without affecting the growth of bacteria and the secretion of the flagellar protein FliC. Among the flavonoids 1-20, licoflavonol (20) exhibited a strong inhibitory effect on the secretion of the SPI-1 effector proteins via regulating the transcription of the SicA/InvF genes, and the transportation of the effector protein SipC. In summary, licoflavonol, a novel natural inhibitor of Salmonella T3SS, could be a promising candidate for novel type of anti-virulence drugs. PMID:27387231

  20. An Easter outbreak of Salmonella Typhimurium DT 104A associated with traditional pork salami in Italy.

    PubMed

    Luzzi, I; Galetta, P; Massari, M; Rizzo, C; Dionisi, A M; Filetici, E; Cawthorne, A; Tozzi, A; Argentieri, M; Bilei, S; Busani, L; Gnesivo, C; Pendenza, A; Piccoli, A; Napoli, P; Loffredo, L; Trinito, M O; Santarelli, E; Ciofi degli Atti, M L

    2007-04-01

    Salmonella enterica is a common cause of gastrointestinal illness in Italy. S. Typhimurium accounts for approximately 40% of isolates, and most of these strains belong to the phage type DT104. We describe the investigation of an outbreak of S. Typhimurium DT104A, a subtype never observed before in Italy, which occurred in Rome during spring 2004.We conducted a matched case control study between 24 July and 9 September 2004. Controls were matched for age and area of residence. Each case had between one and four controls. Odds of exposure to potential risk factors and vehicles for the outbreak were compared between cases and controls. A multivariate analysis was conducted to estimate adjusted Odds Ratios.Sixty-three cases of S. Typhimurium DT 104A infection with onset between 1 April and 5 May 2004 were identified. Sixty-one were residents of Rome and two were residents of a neighbouring region. Twenty-six cases (43%) were enrolled in the study. Their median age was 7.5 years. Fourteen of 26 cases and 16 of 62 controls had eaten pork salami (OR= 25.5; 95% CI 1.6- 416.8). No food samples were available for testing. In northern Italy, two months prior to the outbreak, the veterinary surveillance system identified the first isolation of S. Typhimurium DT104A in a pig isolate. Both human and pig isolates showed indistinguishable PFGE patterns. It was not possible to trace the pig after the sample was taken at slaughter. The epidemiological evidence on the implication of pork salami in this outbreak suggests that pork products can also be a vehicle for salmonella in Italy and underlines the importance of good manufacturing practices for ready-to-eat foods. This investigation highlights the value of laboratory-based surveillance in identifying community-wide outbreaks of uncommon pathogens. It also underlines the need to improve surveillance timeliness, for promptly detecting outbreaks, undergoing field investigation, and implementing control measures. Moreover, our study

  1. Salmonella Typhimurium invasion of HEp-2 epithelial cells in vitro is increased by N-acylhomoserine lactone quorum sensing signals

    PubMed Central

    2011-01-01

    Background In Gram-negative bacteria, the most commonly studied quorum sensing signals are the N-acylhomoserine lactones (AHLs). In Salmonella, AHLs are recognized by SdiA, which is believed to be a sensor of AHLs produced by other bacteria, since Salmonella does not produce AHLs itself. It has been speculated that AHLs produced by the gastrointestinal flora may influence the regulation of virulence traits in Salmonella. The aim of the present work was to study the effect of AHLs on epithelial cell invasion by Salmonella in vitro. Methods Invasion by Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) strain and its isogenc sdiA mutant was studied using a conventional gentamycin invasion assay with HEp-2 cells at 37°C. Gene expression was studied using a semi-quantitative PCR. Results The S. Typhimurium strain, but not its isogenic sdiA mutant, displayed increased in vitro invasion after addition of both N-hexanoyl-DL-homoserine lactone (C6-AHL) and N-octanoyl-DL-homoserine lactone (C8-AHL). Increased expression of two of the genes in the SdiA regulon (rck and srgE) was observed in the wild type strain, but not in the sdiA mutant. Conclusions The results from the present study show that S. Typhimurium can respond to two different AHL quorum sensing signals (C6-AHL and C8-AHL) with increased cell invasion at 37°C in vitro, and that this response most likely is sdiA mediated. These results indicate that if AHLs are present in the intestinal environment, they may increase the invasiveness of Salmonella. PMID:21711544

  2. 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

  3. Effect of Protein SV-IV on Experimental Salmonella enterica Serovar Typhimurium Infection in Mice

    PubMed Central

    Romano-Carratelli, Caterina; Bentivoglio, Concetta; Nuzzo, Immacolata; Benedetto, Nunzia; Buommino, Elisabetta; Cozzolino, Anna; Cartenì, Maria; Morelli, Francesco; Costanza, Maria Rosaria; Metafora, Biancamaria; Metafora, Vittoria; Metafora, Salvatore

    2002-01-01

    Seminal vesicle protein IV (SV-IV) is a secretory anti-inflammatory, procoagulant, and immunomodulatory protein produced in large amounts by the seminal vesicle epithelium of the rat under the strict transcriptional control of androgen. In particular, this protein was shown to possess the ability to markedly inhibit in vivo the humoral and cell-mediated immune responses of mice to nonbacterial cellular antigens (sheep erythrocytes and spermatozoa). We report data that demonstrate that in mice treated with SV-IV and infected with Salmonella enterica serovar Typhimurium, SV-IV is able to downregulate some important immunological and biochemical parameters that serovar Typhimurium normally upregulates in these animals. This event did not correlate with a lower bacterial burden but was associated with a markedly increased one (300%). Furthermore, the treatment of mice with SV-IV alone also produced a significant increase in the rate of mortality among serovar Typhimurium-infected animals. The mechanism underlying these phenomena was investigated, and the strong immunosuppression produced by SV-IV in serovar Typhimurium-infected mice was suggested to be the basis for the increased rate of mortality. The SV-IV-mediated immunosuppression was characterized by a decrease in the humoral and cell-mediated immune responses, altered lymphocyte-macrophage interaction, downregulation of cytokine and inducible nitric oxide synthase gene expression, inhibition of macrophage phagocytosis and intracellular killing activities, and absence of apoptosis in the splenocyte population of SV-IV- and serovar Typhimurium-treated mice. The immunosuppressive activity of SV-IV was specific and was not due to aspecific cytotoxic effects. SV-IV-specific receptors (Kd = 10−8 M) occurring on the macrophage and lymphocyte plasma membranes may be involved in the molecular mechanism underlying the SV-IV-mediated immunosuppression. Some results obtained by the 3-(4,5-dimethylthiazol-2-yl)-2

  4. Effects of gamma irradiation for inactivating Salmonella Typhimurium in peanut butter product during storage.

    PubMed

    Ban, Ga-Hee; Kang, Dong-Hyun

    2014-02-01

    Three types (A, B, and C) of peanut butter product with different water activities (0.18, 0.39, and 0.65 aw) inoculated with a 3-strain mixture of Salmonella Typhimurium were subjected to gamma irradiation (⁶⁰Co) treatment, with doses ranging from 0 to 3 kGy. The inactivation of S. Typhimurium in the 3 types of treated peanut butter product over a 14 day storage period and the influence of storage temperature at 4 (refrigerated) and 25 °C (ambient), and peanut butter product formulation were investigated. Three types of peanut butter product inoculated with S. Typhimurium to a level of ca. 6.6 log CFU/g and subjected to gamma irradiation experienced significant (p<0.05) reductions of 1.3 to 1.9, 2.6 to 2.8, and 3.5 to 4.0 log CFU/g at doses of 1, 2, and 3 kGy, respectively. The time required to reduce S. Typhimurium in peanut butter product to undetectable levels was 14, 5, and 5 days at 25°C after exposure to 3 kGy for products A, B, and C, respectively, and 7 days at 25 °C following exposure to 2 kGy for product C. During storage at 4 and 25 °C, survival of S. Typhimurium was lowest in product C compared to products A and B. Water activity (a(w)) of peanut butter product was likely the most critical factor affecting pathogen survival. When a(w) is reduced, radiolysis of water is reduced, thereby decreasing antimicrobial action. Overall, death was more rapid at 25 °C versus 4 °C for all peanut butter products during 14 day storage. Following gamma irradiation, acid values of peanut butter product were not significantly different from the control, and general observations failed to detect changes in color and aroma, even though lightness observed using a colorimeter was slightly reduced on day 0. The use of gamma irradiation has potential in preventing spoilage of post-packaged food by destroying microorganisms and improving the safety and quality of foods without compromising sensory quality. PMID:24321602

  5. ZBP-89 Regulates Expression of Tryptophan Hydroxylase I and Mucosal Defense Against Salmonella Typhimurium in Mice

    PubMed Central

    Essien, Bryan; Grasberger, Helmut; Romain, Rachael D.; Law, David J.; Veniaminova, Natalia A.; Saqui-Salces, Milena; El-Zaatari, Mohamad; Tessier, Arthur; Hayes, Michael M.; Yang, Alexander C.; Merchant, Juanita L.

    2013-01-01

    Background & Aims ZBP-89 (also ZNF148 or Zfp148) is a butyrate-inducible zinc finger transcription factor that binds to GC-rich DNA elements. Deletion of the N-terminal domain is sufficient to increase mucosal susceptibility to chemical injury and inflammation. We investigated whether conditional deletion of ZBP-89 from the intestinal and colonic epithelium of mice increases their susceptibility to pathogens such as Salmonella typhimurium. Methods We generated mice with a conditional null allele of Zfp148 (ZBP-89FL/FL), using homologous recombination to flank Zfp148 with LoxP sites (ZBP-89FL/FL), and then breeding the resulting mice with those that express VillinCre. We used microarray analysis to compare gene expression patterns in colonic mucosa between ZBP-89FL/FL and C57BL/6 wild-type mice (controls). Mice were gavaged with 2 isogenic strains of S typhimurium after administration of streptomycin. Results Microarray analysis revealed that the colonic mucosa of ZBP-89FL/FL mice had reduced levels of tryptophan hydroxylase 1 (Tph1) mRNA, encoding the rate-limiting enzyme in enterochromaffin cell serotonin (5HT) biosynthesis. DNA affinity precipitation demonstrated direct binding of ZBP-89 to the mouse Tph1 promoter, which was required for its basal and butyrate-inducible expression. ZBP-89FL/FL mice did not increase mucosal levels of 5HT in response to S typhimurium infection and succumbed to the infection 2 days before control mice. The ΔhilA isogenic mutant of S typhimurium lacks this butyrate-regulated locus and stimulated, rather than suppressed, expression of Tph1 approximately 50-fold in control, but not ZBP-89FL/FL mice, correlating with fecal levels of butyrate. Conclusions ZBP-89 is required for butyrate-induced expression of the Tph1 gene and subsequent production of 5HT in response to bacterial infection in mice. Reductions in epithelial ZBP-89 increase susceptibility to colitis and sepsis following infection with S typhimurium, partly due to reduced

  6. Survival of Salmonella Tennessee, Salmonella Typhimurium DT104, and Enterococcus faecium in peanut paste formulations at two different levels of water activity and fat.

    PubMed

    Kataoka, Ai; Enache, Elena; Black, D Glenn; Elliott, Philip H; Napier, Carla D; Podolak, Richard; Hayman, Melinda M

    2014-08-01

    Long-term survival of heat-stressed Salmonella Tennessee, Salmonella Typhimurium DT104, and Enterococcus faecium was evaluated in four model peanut paste formulations with a combination of two water activity (aw) levels (0.3 and 0.6) and two fat levels (47 and 56%) over 12 months at 20 ± 1°C. Prior to storage, the inoculated peanut paste formulations were heat treated at 75°C for up to 50 min to obtain an approximately 1.0-log reduction of each organism. The cell population of each organism in each formulation was monitored with tryptic soy agar plate counts, immediately after heat treatment, at 2 weeks for the first month, and then monthly for up to 1 year. The log reductions (log CFU per gram) following 12 months of storage were between 1.3 and 2.4 for Salmonella Tennessee, 1.8 and 2.8 for Salmonella Typhimurium, and 1.1 and 2.1 for E. faecium in four types of model peanut paste formulations. Enhanced survivability was observed in pastes with lower aw for all organisms, compared with those with higher aw (P < 0.05). In contrast, the effect of fat level (47 and 56%) on survival of all organisms was not statistically significant (P > 0.05). Whereas survivability of Salmonella Tennessee and Typhimurium DT104 did not differ significantly (P > 0.05), E. faecium demonstrated higher survivability than Salmonella (P < 0.05). Salmonella survived in the model peanut pastes well over 12 months, which is longer than the expected shelf life for peanut butter products. The information from this study can be used to design safer food processing and food safety plans for peanut butter processing. PMID:25198585

  7. Effects of residual antibiotics in groundwater on Salmonella typhimurium: changes in antibiotic resistance, in vivo and in vitro pathogenicity.

    PubMed

    Haznedaroglu, Berat Z; Yates, Marylynn V; Maduro, Morris F; Walker, Sharon L

    2012-01-01

    An outbreak-causing strain of Salmonella enterica serovar Typhimurium was exposed to groundwater with residual antibiotics for up to four weeks. Representative concentrations (0.05, 1, and 100 μg L(-1)) of amoxicillin, tetracycline, and a mixture of several other antibiotics (1 μg L(-1) each) were spiked into artificially prepared groundwater (AGW). Antibiotic susceptibility analysis and the virulence response of stressed Salmonella were determined on a weekly basis by using human epithelial cells (HEp2) and soil nematodes (C. elegans). Results have shown that Salmonella typhimurium remains viable for long periods of exposure to antibiotic-supplemented groundwater; however, they failed to cultivate as an indication of a viable but nonculturable state. Prolonged antibiotics exposure did not induce any changes in the antibiotic susceptibility profile of the S. typhimurium strain used in this study. S. typhimurium exposed to 0.05 and 1 μg L(-1) amoxicillin, and 1 μg L(-1) tetracycline showed hyper-virulent profiles in both in vitro and in vivo virulence assays with the HEp2 cells and C. elegans respectively, most evident following 2nd and 3rd weeks of exposure. PMID:22051852

  8. Levels of Expression and Immunogenicity of Attenuated Salmonella enterica Serovar Typhimurium Strains Expressing Escherichia coli Mutant Heat-Labile Enterotoxin

    PubMed Central

    Covone, M. Giuseppina; Brocchi, Marcelo; Palla, Emanuela; da Silveira, W. Dias; Rappuoli, Rino; Galeotti, Cesira L.

    1998-01-01

    The effects of heterologous gene dosage as well as Salmonella typhimurium strain variability on immune response toward both the heterologous antigen, the nontoxic mutant of the Escherichia coli heat-labile enterotoxin LTK63, and the carrier Salmonella strain have been analyzed. Effects of a single integration into the host DNA and different-copy-number episomal vectors were compared in S. typhimurium Δcya Δcrp Δasd strains of two different serotypes, UK-1 and SR-11. Expression of the enterotoxin in the different Salmonella isolates in vitro was found to vary considerably and, for the episomal vectors, to correlate with the plasmid copy number. LTK63-specific serum immunoglobulin G (IgG) and mucosal immunoglobulin A (IgA) antibodies were highest in mice immunized with the high-level-expression strain. High anti-LTK63 IgG and IgA titers were found to correspond to higher anti-Salmonella immunity, suggesting that LTK63 exerts an adjuvant effect on response to the carrier. Statistically significant differences in anti-LTK63 immune response were observed between groups of mice immunized with the attenuated Δcya Δcrp UK-1 and SR-11 derivatives producing the antigen at the same rate. These data indicate that the same attenuation in S. typhimurium strains of different genetic backgrounds can influence significantly the immune response toward the heterologous antigen. Moreover, delivery of the LTK63 enterotoxin to the immune system by attenuated S. typhimurium strains is effective only when synthesis of the antigen is very high during the initial phase of invasion, while persistence of the S. typhimurium strain in deep tissues has only marginal influence. PMID:9423862

  9. Coordinated Regulation of Virulence during Systemic Infection of Salmonella enterica serovar Typhimurium

    SciTech Connect

    Yoon, Hyunjin; McDermott, Jason E.; Porwollik, Steffen; Mcclelland, Michael; Heffron, Fred

    2009-02-20

    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 at 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.

  10. Experimental annotation of post-translational features and translated coding regions in the pathogen Salmonella Typhimurium

    SciTech Connect

    Ansong, Charles; Tolic, Nikola; Purvine, Samuel O.; Porwollik, Steffen; Jones, Marcus B.; Yoon, Hyunjin; Payne, Samuel H.; Martin, Jessica L.; Burnet, Meagan C.; Monroe, Matthew E.; Venepally, Pratap; Smith, Richard D.; Peterson, Scott; Heffron, Fred; Mcclelland, Michael; Adkins, Joshua N.

    2011-08-25

    Complete and accurate genome annotation is crucial for comprehensive and systematic studies of biological systems. For example systems biology-oriented genome scale modeling efforts greatly benefit from accurate annotation of protein-coding genes to develop proper functioning models. However, determining protein-coding genes for most new genomes is almost completely performed by inference, using computational predictions with significant documented error rates (> 15%). Furthermore, gene prediction programs provide no information on biologically important post-translational processing events critical for protein function. With the ability to directly measure peptides arising from expressed proteins, mass spectrometry-based proteomics approaches can be used to augment and verify coding regions of a genomic sequence and importantly detect post-translational processing events. In this study we utilized “shotgun” proteomics to guide accurate primary genome annotation of the bacterial pathogen Salmonella Typhimurium 14028 to facilitate a systems-level understanding of Salmonella biology. The data provides protein-level experimental confirmation for 44% of predicted protein-coding genes, suggests revisions to 48 genes assigned incorrect translational start sites, and uncovers 13 non-annotated genes missed by gene prediction programs. We also present a comprehensive analysis of post-translational processing events in Salmonella, revealing a wide range of complex chemical modifications (70 distinct modifications) and confirming more than 130 signal peptide and N-terminal methionine cleavage events in Salmonella. This study highlights several ways in which proteomics data applied during the primary stages of annotation can improve the quality of genome annotations, especially with regards to the annotation of mature protein products.

  11. Accelerated Cellular Uptake and Metabolism of L-Thyroxine during Acute Salmonella typhimurium Sepsis

    PubMed Central

    DeRubertis, Frederick R.; Woeber, Kenneth A.

    1973-01-01

    The effects of acute Salmonella typhimurium sepsis on the kinetics of peripheral L-thyroxine (T4) distribution and metabolism and on serum total and free T4 concentrations were studied in rhesus monkeys inoculated i.v. with either heat-killed or viable organisms. The rate of disappearance of labeled T4 from serum was increased within 8 h after inoculation of monkeys with either heat-killed or viable Salmonella. The effects of the heat-killed organisms were transient and no longer evident by 16 h postinoculation. The monkeys inoculated with the viable Salmonella experienced a 2-3 day febrile, septic illness that was accompanied by an increase in the absolute rate of T4 disposal. In the infected monkeys, serum total T4 and endogenously labeled protein-bound iodine concentrations fell significantly during the period of acute sepsis and then rose during convalescence to values that exceeded the preinoculation values, suggesting that thyroidal secretion of hormone had increased in response to a primary depletion of the peripheral hormonal pool. Total cellular and hepatic uptakes of T4 were enhanced by 4 h after inoculation of monkeys with either heat-killed or viable Salmonella, but the increase in total cellular uptake persisted for 24 h only in the monkeys inoculated with the viable organisms. These alterations in T4 kinetics could neither be correlated with changes in the binding of T4 in plasma nor attributed to an increase in vascular permeability. Moreover, they could not be ascribed to an in vitro product of bacterial growth, suggesting that the presence of the organisms themselves was required. An acceleration of T4 disappearance was also observed during Escherichia coli and Diplococcus pucumoniae bacteremias. Our findings are consistent with a primary increase in the cellular uptake and metabolism of T4 during bacterial sepsis, possibly related to phagocytic cell function in the host. PMID:4629910

  12. Inactivation of Salmonella Typhimurium in orange juice containing antimicrobial agents by pulsed electric field.

    PubMed

    Liang, Ziwei; Mittal, Gauri S; Griffiths, Mansel W

    2002-07-01

    Combinations of different hurdles, including moderately high temperatures (<60 degrees C), antimicrobial compounds, and pulsed electric field (PEF) treatment, to reduce Salmonella in pasteurized and freshly squeezed orange juices (with and without pulp) were explored. Populations of Salmonella Typhimurium were found to decrease with an increase in pulse number and treatment temperature. At a field strength of 90 kV/cm, a pulse number of 20, and a temperature of 45 degrees C, PEF treatment did not have a notable effect on cell viability or injury. At and above 46 degrees C, however, cell death and injury were greatly increased. Salmonella numbers were reduced by 5.9 log cycles in freshly squeezed orange juice (without pulp) treated at 90 kV/cm, 50 pulses, and 55 degrees C. When PEF treatment was carried out in the presence of nisin (100 U/ml of orange juice), lysozyme (2,400 U/ml), or a mixture of nisin (27.5 U/ml) and lysozyme (690 U/ml), cell viability loss was increased by an additional 0.04 to 2.75 log cycles. The combination of nisin and lysozyme had a more pronounced bactericidal effect than did either nisin or lysozyme alone. An additional Salmonella count reduction of at least 1.37 log cycles was achieved when the two antimicrobial agents were used in combination. No significant difference (P > 0.05) in cell death was attained by lowering the pH value; only cell injury increased. Inactivation by PEF was significantly more extensive (P < 0.05) in pasteurized orange juice than in freshly squeezed orange juice under the same treatment conditions. This increase might be due to the effect of the chemical composition of the juices. PMID:12117238

  13. Direct attachment of nanoparticle cargo to Salmonella typhimurium membranes designed for combination bacteriotherapy against tumors.

    PubMed

    Kazmierczak, Robert; Choe, Elizabeth; Sinclair, Jared; Eisenstark, Abraham

    2015-01-01

    Nanoparticle technology is an emerging approach to resolve difficult-to-manage internal diseases. It is highly regarded, in particular, for medical use in treatment of cancer due to the innate ability of certain nanoparticles to accumulate in the porous environment of tumors and to be toxic to cancer cells. However, the therapeutic success of nanoparticles is limited by the technical difficulty of fully penetrating and thus attacking the tumor. Additionally, while nanoparticles possess seeming-specificity due to the unique physiological properties of tumors themselves, it is difficult to tailor the delivery of nanoparticles or drugs in other models, such as use in cardiac disease, to the specific target. Thus, a need for delivery systems that will accurately and precisely bring nanoparticles carrying drug payloads to their intended sites currently exists. Our solution to this engineering challenge is to load such nanoparticles onto a biological "mailman" (a novel, nontoxic, therapeutic strain of Salmonella typhimurium engineered to preferentially and precisely seek out, penetrate, and hinder prostate cancer cells as the biological delivery system) that will deliver the therapeutics to a target site. In this chapter, we describe two methods that establish proof-of-concept for our cargo loading and delivery system by attaching nanoparticles to the Salmonella membrane. The first method (Subheading 1.1) describes association of sucrose-conjugated gold nanoparticles to the surface of Salmonella bacteria. The second method (Subheading 1.2) biotinylates the native Salmonella membrane to attach streptavidin-conjugated fluorophores as example nanoparticle cargo, with an alternative method (expression of membrane bound biotin target sites using autodisplay plasmid vectors) that increases the concentration of biotin on the membrane surface for streptavidin-conjugated nanoparticle attachment. By directly attaching the fluorophores to our bacterial vector through biocompatible

  14. Plasmid studies of Salmonella typhimurium phage type 179 resistant to ampicillin, tetracycline, sulphonamides and trimethoprim.

    PubMed Central

    Anderson, D. M.

    1980-01-01

    Sixteen strains of Salmonella typhimurium phage type 179 were referred to the National Health Institute, Wellington, New Zealand, from 1977 to 1979. This phage type had not been observed here before 1977. All strains were resistant to ampicillin, several were also resistant to tetracycline, and several were resistant to ampicillin, tetracycline, sulphafurazole and trimethoprim. All resistances could be transferred to Escherichia coli K 12. Plasmids from these strains and their transconjugants were characterized by agarose gel electrophoresis. It appears that resistance to sulphafurazole and trimethoprim is carried on a plasmid with a molecular weight of 5 . 2 Mdal and that resistance to ampicillin and tetracycline is carried on a plasmid with a molecular weight of approximately 60 Mdal. Images Plate 1 PMID:7005330

  15. Mutagenic activity of cytostatic methyl hydrazones with different strains of Salmonella typhimurium.

    PubMed

    Gericke, D; Braun, R; Dittmar, W

    1979-07-11

    Experiments are performed to ascertain the mutagenic properties of four new cytostatic methyl-hydrazones in the Ames test using different strains of Salmonella typhimurium. As could be demonstrated all four hydrazones are mutagenic per se without a metabolic activation through rat liver microsomes (S-9 fraction). Whereas the beta-chloroethyl hydrazones B1 and B2 cause a base-pair substitution with the strains TA100 and TA1535 the methyl-hydrazones EB4 and CyB4 both cause base-pair substitution with TA100 and frameshift mutation with TA98. At both strains the mutagenic activity of Cy84 ist powerful. Furthermore, no relation could be detected between the mutagenic properties of the methyl-hydrazones and their alkylating behaviour on 4-(4-nitrobenzyl)-pyridine. PMID:383045

  16. Novel hexamerization motif is discovered in a conserved cytoplasmic protein from Salmonella typhimurium.

    SciTech Connect

    Petrova, T.; Cuff, M.; Wu, R.; Kim, Y.; Holzle, D.; Joachimiak, A.; Biosciences Division; Inst. of Mathematical Problems of Biology

    2007-01-01

    The cytoplasmic protein Stm3548 of unknown function obtained from a strain of Salmonella typhimurium was determined by X-ray crystallography at a resolution of 2.25 A. The asymmetric unit contains a hexamer of structurally identical monomers. The monomer is a globular domain with a long beta-hairpin protrusion that distinguishes this structure. This beta-hairpin occupies a central position in the hexamer, and its residues participate in the majority of interactions between subunits of the hexamer. We suggest that the structure of Stm3548 presents a new hexamerization motif. Because the residues participating in interdomain interactions are highly conserved among close members of protein family DUF1355 and buried solvent accessible area for the hexamer is significant, the hexamer is most likely conserved as well. A light scattering experiment confirmed the presence of hexamer in solution.

  17. Evaluation of mutagenicity testing with Salmonella typhimurium TA102 in three different laboratories.

    PubMed Central

    Müller, W; Engelhart, G; Herbold, B; Jäckh, R; Jung, R

    1993-01-01

    Thirty compounds of various chemical classes were investigated for mutagenicity in a collaborative study (three laboratories) using Salmonella typhimurium TA102. With five compounds, hydrazine sulfate, phenylhydrazine, hydralazine, glutardialdehyde, and glyoxal, mutagenicity was detected by all laboratories. Formaldehyde was assessed as weakly mutagenic in only one of three laboratories. The remaining 24 agents were uniformly described as non-genotoxic in TA102. In spite of the overall good qualitative agreement in the mutagenicity results between the three laboratories, some quantitative discrepancies occurred in the dose response of the mutagenic compounds. Varying inter- and intralaboratory differences in the spontaneous rate of revertants were obtained. The usefulness of the tester strain TA102 in routine mutagenicity testing is discussed. PMID:8143640

  18. High-Throughput CRISPR Typing of Mycobacterium tuberculosis Complex and Salmonella enterica Serotype Typhimurium.

    PubMed

    Sola, Christophe; Abadia, Edgar; Le Hello, Simon; Weill, François-Xavier

    2015-01-01

    Spoligotyping was developed almost 18 years ago and still remains a popular first-lane genotyping technique to identify and subtype Mycobacterium tuberculosis complex (MTC) clinical isolates at a phylogeographic level. For other pathogens, such as Salmonella enterica, recent studies suggest that specifically designed spoligotyping techniques could be interesting for public health purposes. Spoligotyping was in its original format a reverse line-blot hybridization method using capture probes designed on "spacers" and attached to a membrane's surface and a PCR product obtained from clustered regularly interspaced short palindromic repeats (CRISPRs). Cowan et al. and Fabre et al. were the first to propose a high-throughput Spoligotyping method based on microbeads for MTC and S. enterica serotype Typhimurium, respectively. The main advantages of the high-throughput Spoligotyping techniques we describe here are their low cost, their robustness, and the existence (at least for MTC) of very large databases that allow comparisons between spoligotypes from anywhere. PMID:25981468

  19. Isoleucine starvation caused by sulfometuron methyl in Salmonella typhimurium measured by translational frameshifting.

    PubMed

    Kaplun, Alexander; Chipman, David M; Barak, Ze'ev

    2002-03-01

    The authors have developed a tool for the study of inhibitor-induced amino acid starvation in bacteria which exploits the phenomenon of translational frameshifting. The inhibition of acetohydroxyacid synthase II by the herbicide sulfometuron methyl (SMM) has complex effects on branched-chain amino acid biosynthesis. Experiments were done with Salmonella typhimurium containing a plasmid with an isoleucine codon in a 'shifty' region, prone to translational frameshifting. SMM did not cause translational frameshifting in minimal medium under conditions that inhibit growth. A 20-fold higher concentration of SMM was required to cause starvation for isoleucine, e.g. in the presence of valine. This starvation was reflected in translational frameshifting correlated with inhibition of growth. These observations support the authors' previous suggestions based on other techniques. The method used here could be generalized for the study of complex metabolic effects related to amino acids. PMID:11882705

  20. Evidence for isoleucine as a positive effector of the ilvBN operon in Salmonella typhimurium.

    PubMed

    Davidson, J P; Wilson, D J

    1991-08-15

    Concerted efforts were directed towards understanding the control of acetohydroxy acid synthase (AHAS) in the gyrB mutant hisU1820 of Salmonella typhimurium. A media shift from valine to valine plus isoleucine causes a dramatic 4 to 5 fold burst of AHAS valine sensitive activity which appears to be dependent on translation. DJ19, an isolated valine sensitive derivative of the gyrB mutant, maintains a dramatic increase in AHAS valine sensitive activity upon the addition of isoleucine to valine supplemented cultures, suggesting that the isoleucine effect is specific for valine sensitive AHAS. Evidence supports isoleucine as a positive effector on valine sensitive AHAS expression and that the gyrB mutation accentuates the isoleucine effect. PMID:1872874

  1. Mutagenicity of steviol and its oxidative derivatives in Salmonella typhimurium TM677.

    PubMed

    Terai, Tadamasa; Ren, Huifeng; Mori, Go; Yamaguchi, Yoshihito; Hayashi, Tetsuhito

    2002-07-01

    Stevioside is natural non-caloric sweetner isolated from Stevia rebaudiana BERTONI, which has been used as a non-caloric sugar substitute in Japan. Pezzuto et al. demonstrated that steviol shows a dose-dependent positive response in forward mutation assay using Salmonella typhimurium TM677 in the presence of metabolic activation system (Aroclor induced rat liver S9 fraction). Our studies were carried out to identify the genuine mutagenic active substance from among the eight steviol derivatives. Steviol indicate almost similar levels of mutagenicity under the presence of S9 mixture, as reported by Pezzuto et al. 15-Oxo-steviol was found to be mutagenic at the one tenth the level of steviol itself under the presence of S9 mixture. Interestingly, specific mutagenicity of the lactone derivative under the presence of S9 mixture was ten times lower than that of the lactone derivative without the addition of S9 mixture. PMID:12130868

  2. Effect of substitution of monovalent anions in external medium on the swimming pattern of Salmonella typhimurium.

    PubMed Central

    Hosoi, S; Oosawa, F

    1978-01-01

    The effect of replacement of ions in the extracellular medium on the swimming pattern of bacteria (Salmonella typhimurium) has been investigated. The replacement of chloride ion (Cl-) in the standard medium by methanesulfonate ion (MS-) or by propionate ion (Pr-) induced an increase in the tumbling frequency, or a decrease of the end-to-end distances of tracks. Replacement of MS- by Cl- resulted in transient depression of tumbling, and replacement of Pr- by Cl- resulted in immediate recovery of normal swimming. The replacement of cations was not very effective. The experimental data, including the dependence of the effect of replacement on the ion concentration, are consistent with the ideas that the tumbling frequency increases with depolarization of the bacterial membrane and that such anions as MS- and Pr- are more able to permeate the membrane than is Cl-. Images PMID:207676

  3. Outer Membrane Permeability Barrier Disruption by Polymyxin in Polymyxin-Susceptible and -Resistant Salmonella typhimurium

    PubMed Central

    Vaara, Martti; Vaara, Timo

    1981-01-01

    In contrast to their polymyxin-susceptible parent strains, polymyxin-resistant Salmonella typhimurium mutants (pmrA strains) did not lose their outer membrane permeability barrier to macromolecules such as lysozyme and periplasmic proteins upon polymyxin treatment. The sensitization of pmrA strains to deoxycholate-induced lysis required 10-times-higher polymyxin concentrations than did the sensitization of the parent strains. These findings indicate that the pmrA mutation affects the outer membrane and decreases its susceptibility to polymyxin. By contrast, the pmrA mutants did not differ from their parents in the uptake of gentian violet after treatment with polymyxin, suggesting a degree of specificity in the pmrA effect in the outer membrane. Images PMID:6264852

  4. Fine-structure map of the histidine transport genes in Salmonella typhimurium.

    PubMed Central

    Ames, G F; Noel, K D; Taber, H; Spudich, E N; Nikaido, K; Afong, J

    1977-01-01

    Afine-structure genetic map of the histidine transport region of the Salmonella typhimurium chromosome was constructed. Twenty-five deletion mutants were isolated and used for dividing the hisJ and hisP genes into 8 and 13 regions respectively. A total of 308 mutations, spontaneous and mutagen induced, have been placed in these regions by deletion mapping. The histidine transport operon is presumed to be constituted of genes dhuA, hisJ, and hisP, and the regulation of the hosP and hisJ genes by dhuA is discussed. The orientation of this operon relative to purF has been established by three-point crosses as being: purF duhA hisJ hisP. PMID:321422

  5. Fine-structure map of the histidine transport genes in Salmonella typhimurium.

    PubMed

    Ames, G F; Noel, K D; Taber, H; Spudich, E N; Nikaido, K; Afong, J

    1977-03-01

    Afine-structure genetic map of the histidine transport region of the Salmonella typhimurium chromosome was constructed. Twenty-five deletion mutants were isolated and used for dividing the hisJ and hisP genes into 8 and 13 regions respectively. A total of 308 mutations, spontaneous and mutagen induced, have been placed in these regions by deletion mapping. The histidine transport operon is presumed to be constituted of genes dhuA, hisJ, and hisP, and the regulation of the hosP and hisJ genes by dhuA is discussed. The orientation of this operon relative to purF has been established by three-point crosses as being: purF duhA hisJ hisP. PMID:321422

  6. The QseB Response Regulator is Required for Decreased Bacterial Motility and Swine Colonization in a QseC Mutant of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inactivation of the QseC (PreB) sensor kinase decreases the motility of a qseC mutant compared to wild-type Salmonella enterica serovar Typhimurium (S. Typhimurium). In addition, the competitive fitness of the qseC mutant for colonization of the swine gastrointestinal tract is decreased compared to...

  7. Upregulation of STM3175 Decreases Bacterial Motility and Swine Colonization in a qseC (preB) Mutant of Salmonella enterica serovar Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inactivation of the QseC (PreB) sensor kinase decreases bacterial motility and pathogen colonization of the swine gastrointestinal tract for Salmonella enterica serovar Typhimurium (S. Typhimurium). In contrast, both the qseB [encoding the QseB (PreA) response regulator] and qseBC mutants had motil...

  8. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. Stability of plasmids R1-19 and R100 in hyper-recombinant Escherichia coli strains and in Salmonella typhimurium strains.

    PubMed Central

    Gómez-Eichelmann, M C; Torres, H K

    1983-01-01

    Plasmids R1-19 and R100 dissociate in hyper-recominant Escherichia coli strains in a way that is similar to but slower than dissociation in Salmonella typhimurium. The results presented suggest that the molecular mechanism for plasmid dissociation in hyper-recombinant E. coli strains is different than that in S. typhimurium strains. PMID:6343357

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  11. Cell yields and fermentation responses of a Salmonella Typhimurium poultry isolate at different dilution rates in an anaerobic steady state continuous culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of these studies were to determine cell yield and fermentation responses of a Salmonella enterica serovar Typhimurium poultry isolate using various dilution rates in steady state continuous culture incubations. S. enterica Typhimurium cells were propagated in continuous cultures with ...

  12. Sensitivity of mycobacterium avium subsp paratuberculosis, escherichia coli and salmonella enterica serotype typhimurium to low pH, high organic acids and ensiling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of Mycobacterium avium subsp paratuberculosis (M. paratuberculosis), Salmonella enterica serotype Typhimurium (S. Typhimurium) and a commensal Escherichia coli (E. coli) isolate to persist under low pH and high organic acid conditions was determined. Die-off rates were calculated followi...

  13. Effects of indole on drug resistance and virulence of Salmonella enterica serovar Typhimurium revealed by genome-wide analyses

    PubMed Central

    2012-01-01

    Background Many Gram-positive and Gram-negative bacteria produce large quantities of indole as an intercellular signal in microbial communities. Indole demonstrated to affect gene expression in Escherichia coli as an intra-species signaling molecule. In contrast to E. coli, Salmonella does not produce indole because it does not harbor tnaA, which encodes the enzyme responsible for tryptophan metabolism. Our previous study demonstrated that E. coli-conditioned medium and indole induce expression of the AcrAB multidrug efflux pump in Salmonella enterica serovar Typhimurium for inter-species communication; however, the global effect of indole on genes in Salmonella remains unknown. Results To understand the complete picture of genes regulated by indole, we performed DNA microarray analysis of genes in the S. enterica serovar Typhimurium strain ATCC 14028s affected by indole. Predicted Salmonella phenotypes affected by indole based on the microarray data were also examined in this study. Indole induced expression of genes related to efflux-mediated multidrug resistance, including ramA and acrAB, and repressed those related to host cell invasion encoded in the Salmonella pathogenicity island 1, and flagella production. Reduction of invasive activity and motility of Salmonella by indole was also observed phenotypically. Conclusion Our results suggest that indole is an important signaling molecule for inter-species communication to control drug resistance and virulence of S. enterica. PMID:22632036

  14. Interdigitated microelectrode (IME) impedance sensor for the detection of viable Salmonella typhimurium.

    PubMed

    Yang, Liju; Li, Yanbin; Griffis, Carl L; Johnson, Michael G

    2004-05-15

    Interdigitated microelectrodes (IMEs) were used as impedance sensors for rapid detection of viable Salmonella typhimurium in a selective medium and milk samples. The impedance growth curves, impedance against bacterial growth time, were recorded at four frequencies (10Hz, 100Hz, 1kHz, and 10kHz) during the growth of S. typhimurium. The impedance did not change until the cell number reached 10(5)-10(6) CFUml(-1). The greatest change in impedance was observed at 10Hz. To better understand the mechanism of the IME impedance sensor, an equivalent electrical circuit, consisting of double layer capacitors, a dielectric capacitor, and a medium resistor, was introduced and used for interpreting the change in impedance during bacterial growth. Bacterial attachment to the electrode surface was observed with scanning electron microscopy, and it had effect on the impedance measurement. The detection time, t(D), defined as the time for the impedance to start change, was obtained from the impedance growth curve at 10Hz and had a linear relationship with the logarithmic value of the initial cell number of S. typhimurium in the medium and milk samples. The regression equations for the cell numbers between 4.8 and 5.4 x 10(5) CFUml(-1) were t(D) = -1.38 log N + 10.18 with R(2) = 0.99 in the pure medium and t(D) = -1.54 log N + 11.33 with R(2) = 0.98 in milk samples, respectively. The detection times for 4.8 and 5.4 x 10(5) CFUml(-1) initial cell numbers were 9.3 and 2.2 h, respectively, and the detection limit could be as low as 1 cell in a sample. PMID:15046744

  15. An oxygen-dependent coproporphyrinogen oxidase encoded by the hemF gene of Salmonella typhimurium.

    PubMed Central

    Xu, K; Elliott, T

    1993-01-01

    The 8th step in the 10-step heme biosynthetic pathway of Salmonella typhimurium is the oxidation of coproporphyrinogen III to protoporphyrinogen IX. On the basis of genetic studies, we have suggested that this reaction may be catalyzed by either of two different enzymes, an oxygen-dependent one encoded by hemF or an oxygen-independent enzyme encoded by hemN. Here, we report the cloning of the S. typhimurium hemF gene and its DNA sequence. The predicted amino acid sequence of the HemF protein is 44% identical to that of the coproporphyrinogen oxidase encoded by the yeast HEM13 gene. The wild-type S. typhimurium strain LT-2 produces an oxygen-dependent coproporphyrinogen oxidase activity detectable in crude extracts, which is not found in hemF mutants and is overproduced in strains carrying the hemF gene on a multicopy plasmid. the hemF gene is the second gene in an operon with an upstream gene with an unknown function, whose amino acid sequence suggests a relation to amidases involved in cell wall synthesis or remodeling. The upstream gene and hemF are cotranscribed from a promoter which was mapped by primer extension. A weaker, hemF-specific promoter is inferred from the behavior of an omega-Cm insertion mutation in the upstream gene. Although this insertion decreases expression of beta-galactosidase about 7.5-fold when placed upstream of a hemF-lacZ operon fusion, it still allows sufficient HemF expression from an otherwise wild-type construct to confer a Hem+ phenotype. The hemF operon is transcribed clockwise with respect to the genetic map. Images PMID:8349542

  16. Functionalized polymeric magnetic nanoconstructs for selective capturing and sensitive detection of Salmonella typhimurium.

    PubMed

    Chattopadhyay, Sruti; Kaur, Avneet; Jain, Swati; Sabharwal, Prabhjot K; Singh, Harpal

    2016-09-21

    Rapid detection and enumeration of pathogens is essential for monitoring contamination and spoilage of food products to ensure improved quality control management. Functionalized polymeric magnetic nanoconstructs (FPMNCs) were developed as an effective immunomagnetic separator and sensing platform for the selective capturing of Salmonella typhimurium. Novel FPMNCs were prepared in three stages involving synthesis of iron oxide (IO) dispersion, capping with sodium oleate and encapsulation of preformed IO nanoparticles by in-situ free radical emulsion polymerization of styrene (St), methyl methacrylate (MMA) and acetoacetoxy ethylmethacrylate (AAEM). PMMA improves the stability of FPMNCs by bridging extremely hydrophobic PS and hydrophilic PAAEM. Core-shell morphology of hydrophobic core of IO, PS & PMMA and hydrophilic shell of PAAEM was demonstrated by SEM, TEM and FTIR studies. FPMNCs with surface functionalized acetoacetoxy groups were covalently attached with polyclonal antibodies against Salmonella common structural antigen (CSA-1-Ab) without using any linker and catalyst. Colorimetric readout signal was acquired using CSA-1-Ab-HRP as secondary antibody after formation of sandwich immunocomplex with bacteria where the optical density of the samples were recorded using ELISA plate reader at 450 nm. The developed immunoassay was specific and selective which captures only targeted S. typhimurium with a detection limit of 10 cells/mL lower than infectious dose of salmonellosis infection. Minimal interference of food matrix with high signal to noise ratio was shown by various food samples. In addition, the performance of developed FPMNC based immunoassay was superior to commercially available immunomagnetic microbeads demonstrating undisputed advantage for capturing and detecting specific bacteria without any pre-enrichment of sample. PMID:27590554

  17. Purification and properties of two binding proteins for branched-chain amino acids in Salmonella typhimurium.

    PubMed

    Ohnishi, K; Kiritani, K

    1983-08-01

    Two leucine-binding proteins isolated from osmotic shock fluid of Salmonella typhimurium LT2 were purified by DEAE-cellulose and DEAE-Sephadex A-50 chromatography, and subsequent isoelectric focusing. These purified binding proteins could be crystallized by adding 2-methyl-2,4-pentanediol. One of the binding proteins, designated as LIVT-binding protein, binds L-leucine, L-isoleucine, L-valine, and L-threonine, while the other, L-binding protein, binds only L-leucine. The level of LIVT-binding protein in the shock fluid was about three-fold higher than that of L-binding protein. The molecular weight of the LIVT-binding protein was estimated to be 35,000 by gel filtration, and 39,000 by gel electrophoresis. The isoelectric point was pH 4.94. The dissociation constants of this protein for leucine, isoleucine, and valine were 0.43, 0.15, and 0.89 microM, respectively. For the L-binding protein, molecular weights of 34,000 (gel filtration), and 38,000 (gel electrophoresis) were obtained. The isoelectric point was pH 4.74. The dissociation constant of this protein for leucine was 0.54 microM. The LIVT-binding protein was more heat-stable than the L-binding protein. These two binding proteins showed an antigenic similarity, they could cross-react with each other's antiserum. This similarity was also found between the binding proteins of Salmonella typhimurium and Escherichia coli K-12. Both LIVT- and L-binding proteins in a regulatory mutant, KA2313, were found to be about three-fold the levels in the wild-type strain. PMID:6355077

  18. Longitudinal characterization of monophasic Salmonella Typhimurium throughout the pig's life cycle.

    PubMed

    Fernandes, Laura; Centeno, Maria Madalena; Couto, Natacha; Nunes, Telmo; Almeida, Virgílio; Alban, Lis; Pomba, Constança

    2016-08-30

    Swine have been described as an important reservoir of multidrug resistant monophasic Salmonella Typhimurium, though information on its ecology is scarce. A longitudinal study was performed in order to elucidate the Salmonella 4,[5],12:i:- dynamics throughout the pig's production cycle. A total of 209 faecal samples were collected from 10 sows and in six sampling times during the life of 70 pigs from a Portuguese industrial farm, and 43 isolates of S. 4,[5],12:i:- were identified and characterized regarding clonality and antimicrobial resistance phenotype and genotype. Most isolates (n=42) exhibited resistance to at least ampicillin, kanamycin, neomycin, streptomycin, tetracycline and sulfonamides (encoded by blaTEM, aphAI-IAB, strA, strB, tetB and sul2, respectively). Isolates obtained during the finishing phase showed additional resistance to chloramphenicol and florfenicol (floR), gentamicin and netilmicin (aac(3')-IV). To our knowledge, this study is the first description of aphAI-IAB in S. 4,[5],12:i:-. PFGE analysis showed uneven distribution of isolates into three clusters, A (n=34), B (n=8) and C (n=1). PFGE cluster A was predominant in sows (n=5) and piglets in the farrowing phase (n=17) and in pigs in the early finishing phase (n=11) suggesting a carryover from birth to adult age. The introduction of PFGE cluster B isolates in adulthood could have had an external source, reinforcing the relevance of environmental transmission in the farm ecosystem. This study reveals a dynamic interaction between monophasic S. Typhimurium and the pressures exerted under an intensive swine production setting. PMID:27527788

  19. Behavior of Salmonella typhimurium DT104 during the manufacture and storage of pepperoni.

    PubMed

    Ihnot, A M; Roering, A M; Wierzba, R K; Faith, N G; Luchansky, J B

    1998-03-01

    Pepperoni batter (ca. 70% pork:30% beef) was prepared and subsequently inoculated with a six-strain cocktail (ca. 4.4 x 10(7) per gram batter) of Salmonella typhimurium DT104. After fermentation at 36 degrees C and 92% relative humidity (RH) to < or = pH 4.8, counts of the pathogen decreased by about 1.3 log10 units. An additional 1.6 log10 unit decrease was observed following drying at 13 degrees C and 65% RH to a moisture protein ratio (M/Pr) of 1.6:1. After storage of pepperoni sticks for 56 days under vacuum at 4 or 21 degrees C, counts of the pathogen were about 4.6 and 6.6 log10 units lower, respectively, compared with starting levels in the batter. These data establish that fermentation and drying result in about a 3.0 log10 reduction in numbers of S typhimurium DT104 in pepperoni sticks and that storage of pepperoni sticks under vacuum at ambient temperature is more severe on the pathogen than refrigerated storage. PMID:9600617

  20. 2.3THz radiation: Absence of genotoxicity/mutagenicity in Escherichia coli and Salmonella typhimurium.

    PubMed

    Sergeeva, Svetlana; Demidova, Elisaveta; Sinitsyna, Olga; Goryachkovskaya, Tatiana; Bryanskaya, Alla; Semenov, Artem; Meshcheryakova, Irina; Dianov, Grigory; Popik, Vasiliy; Peltek, Sergey

    2016-06-01

    The mutagenicity and genotoxicity in bacteria of 2.3THz radiation (THz) produced by a free-electron laser (NovoFEL) were evaluated; exposures were 5, 10, or 15min at average power 1.4W/cm(2). Two Ames mutagenicity test strains of Salmonella typhimurium, TA98 and TA102, were used. For the genotoxicity test, we measured SOS induction in Escherichia coli PQ37. No significant differences were found between exposed and control cells, indicating that THz radiation is neither mutagenic nor genotoxic under these conditions. Nevertheless, a small increase in total cell number of S. typhimurium after 15min exposure, and an increase in β-galactosidase and alkaline phosphatase activities in E.coli PQ37, were observed, indicating some effect of THz radiation on cell metabolism. We also examined the combined effect of 4-NQO (8μM; positive control) and THz exposure (5min) on genotoxicity in E.coli PQ37. Unexpectedly, THz radiation decreased 4-NQO genotoxicity. PMID:27265378

  1. Aptasensors for rapid detection of Escherichia coli O157:H7 and Salmonella typhimurium

    NASA Astrophysics Data System (ADS)

    Wu, Wen-he; Li, Min; Wang, Yue; Ouyang, Hou-xian; Wang, Lin; Li, Ci-xiu; Cao, Yu-chen; Meng, Qing-he; Lu, Jian-xin

    2012-11-01

    Herein we reported the development of aptamer-based biosensors (aptasensors) based on label-free aptamers and gold nanoparticles (AuNPs) for detection of Escherichia coli ( E. coli) O157:H7 and Salmonella typhimurium. Target bacteria binding aptamers are adsorbed on the surface of unmodified AuNPs to capture target bacteria, and the detection was accomplished by target bacteria-induced aggregation of the aptasensor which is associated as red-to-purple color change upon high-salt conditions. By employing anti- E. coli O157:H7 aptamer and anti- S. typhimurium aptamer, we developed a convenient and rapid approach that could selectively detect bacteria without specialized instrumentation and pretreatment steps such as cell lysis. The aptasensor could detect as low as 105colony-forming units (CFU)/ml target bacteria within 20 min or less and its specificity was 100%. This novel method has a great potential application in rapid detection of bacteria in the near future.

  2. An outbreak of Salmonella typhimurium DT170 associated with kebab meat and yogurt relish.

    PubMed Central

    Evans, M. R.; Salmon, R. L.; Nehaul, L.; Mably, S.; Wafford, L.; Nolan-Farrell, M. Z.; Gardner, D.; Ribeiro, C. D.

    1999-01-01

    During July 1995, an outbreak of Salmonella typhimurium definitive type (DT) 170, an unusual strain, occurred in South Wales. A case-control study found that illness was associated with eating kebabs (odds ratio undefined, P = 0.002), doner kebabs (odds ratio 7.9, 95 % confidence interval 1.5-20.5, P = 0.02) and kebabs with yoghurt based relish (odds ratio undefined, P = 0.009) but not with eating kebabs with mayonnaise-based relish (odds ratio 2.4, 95 % confidence interval 0.4-13.9, P = 0.53). Environmental investigations discovered a complex web of producers and wholesale suppliers. Kebab meat and yoghurt had been supplied to the two main implicated outlets by a single wholesaler. Samples of raw minced lamb and several environmental swabs taken at the wholesaler were positive for S. typhimurium DT170. Blood-stained, unsealed yoghurt pots were observed to be stored under a rack of raw lamb. Investigators of food poisoning outbreaks linked to takeaway food should consider cross-contaminated relishes and dressings as well as undercooked meat as potential vehicles of infection. PMID:10459639

  3. A low-pH-inducible, stationary-phase acid tolerance response in Salmonella typhimurium.

    PubMed Central

    Lee, I S; Slonczewski, J L; Foster, J W

    1994-01-01

    Acid is an important environmental condition encountered by Salmonella typhimurium during its pathogenesis. Our studies have shown that the organism can actively adapt to survive potentially lethal acid exposures by way of at least three possibly overlapping systems. The first is a two-stage system induced in response to low pH by logarithmic-phase cells called the log-phase acid tolerance response (ATR). It involves a major molecular realignment of the cell including the induction of over 40 proteins. The present data reveal that two additional systems of acid resistance occur in stationary-phase cells. One is a pH-dependent system distinct from log-phase ATR called stationary-phase ATR. It was shown to provide a higher level of acid resistance than log-phase ATR but involved the synthesis of fewer proteins. Maximum induction of stationary-phase ATR occurred at pH 4.3. A third system of acid resistance is not induced by low pH but appears to be part of a general stress resistance induced by stationary phase. This last system requires the alternative sigma factor, RpoS. Regulation of log-phase ATR and stationary-phase ATR remains RpoS independent. Although the three systems are for the most part distinct from each other, together they afford maximum acid resistance for S. typhimurium. Images PMID:8113183

  4. Actin restructuring during Salmonella typhimurium infection investigated by confocal and super-resolution microscopy

    NASA Astrophysics Data System (ADS)

    Han, Jason J.; Kunde, Yuliya A.; Hong-Geller, Elizabeth; Werner, James H.

    2014-01-01

    We have used super-resolution optical microscopy and confocal microscopy to visualize the cytoskeletal restructuring of HeLa cells that accompanies and enables Salmonella typhimurium internalization. Herein, we report the use of confocal microscopy to verify and explore infection conditions that would be compatible with super-resolution optical microscopy, using Alexa-488 labeled phalloidin to stain the actin cytoskeletal network. While it is well known that actin restructuring and cytoskeletal rearrangements often accompany and assist in bacterial infection, most studies have employed conventional diffraction-limited fluorescence microscopy to explore these changes. Here we show that the superior spatial resolution provided by single-molecule localization methods (such as direct stochastic optical reconstruction microscopy) enables more precise visualization of the nanoscale changes in the actin cytoskeleton that accompany bacterial infection. In particular, we found that a thin (100-nm) ring of actin often surrounds an invading bacteria 10 to 20 min postinfection, with this ring being transitory in nature. We estimate that a few hundred monofilaments of actin surround the S. typhimurium in this heretofore unreported bacterial internalization intermediate.

  5. A Network Inference Workflow Applied to Virulence-Related Processes in Salmonella typhimurium

    SciTech Connect

    Taylor, Ronald C.; Singhal, Mudita; Weller, Jennifer B.; Khoshnevis, Saeed; Shi, Liang; McDermott, Jason E.

    2009-04-20

    Inference of the structure of mRNA transcriptional regulatory networks, protein regulatory or interaction networks, and protein activation/inactivation-based signal transduction networks are critical tasks in systems biology. In this article we discuss a workflow for the reconstruction of parts of the transcriptional regulatory network of the pathogenic bacterium Salmonella typhimurium based on the information contained in sets of microarray gene expression data now available for that organism, and describe our results obtained by following this workflow. The primary tool is one of the network inference algorithms deployed in the Software Environment for BIological Network Inference (SEBINI). Specifically, we selected the algorithm called Context Likelihood of Relatedness (CLR), which uses the mutual information contained in the gene expression data to infer regulatory connections. The associated analysis pipeline automatically stores the inferred edges from the CLR runs within SEBINI and, upon request, transfers the inferred edges into either Cytoscape or the plug-in Collective Analysis of Biological of Biological Interaction Networks (CABIN) tool for further post-analysis of the inferred regulatory edges. The following article presents the outcome of this workflow, as well as the protocols followed for microarray data collection, data cleansing, and network inference. Our analysis revealed several interesting interactions, functional groups, metabolic pathways, and regulons in S. typhimurium.

  6. Genetics of Swarming Motility in Salmonella enterica Serovar Typhimurium: Critical Role for Lipopolysaccharide

    PubMed Central

    Toguchi, Adam; Siano, Michael; Burkart, Mark; Harshey, Rasika M.

    2000-01-01

    Salmonella enterica serovar Typhimurium can differentiate into hyperflagellated swarmer cells on agar of an appropriate consistency (0.5 to 0.8%), allowing efficient colonization of the growth surface. Flagella are essential for this form of motility. In order to identify genes involved in swarming, we carried out extensive transposon mutagenesis of serovar Typhimurium, screening for those that had functional flagella yet were unable to swarm. A majority of these mutants were defective in lipopolysaccharide (LPS) synthesis, a large number were defective in chemotaxis, and some had defects in putative two-component signaling components. While the latter two classes were defective in swarmer cell differentiation, representative LPS mutants were not and could be rescued for swarming by external addition of a biosurfactant. A mutation in waaG (LPS core modification) secreted copious amounts of slime and showed a precocious swarming phenotype. We suggest that the O antigen improves surface “wettability” required for swarm colony expansion, that the LPS core could play a role in slime generation, and that multiple two-component systems cooperate to promote swarmer cell differentiation. The failure to identify specific swarming signals such as amino acids, pH changes, oxygen, iron starvation, increased viscosity, flagellar rotation, or autoinducers leads us to consider a model in which the external slime is itself both the signal and the milieu for swarming motility. The model explains the cell density dependence of the swarming phenomenon. PMID:11053374

  7. Antimutagenic effects of aqueous fraction of Myristica fragrans (Houtt.) leaves on Salmonella typhimurium and Mus musculus.

    PubMed

    Akinboro, Akeem; Bin Mohamed, Kamaruzaman; Asmawi, Mohd Zaini; Yekeen, Taofeek A

    2014-01-01

    Natural plant extracts offer a promising hope in the prevention/treatment of cancer arising from genetic mutations. This study evaluated in vitro and in vivo mutagenic and antimutagenic effects of aqueous fraction of Myristica fragrans (AFMF) leaves on TA100 strain of Salmonella typhimurium and Mus musculus (Male Swiss albino mice), respectively. The antioxidant activity of AFMF against 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic and flavonoid contents were determined, followed by its phytochemical elucidation using the Ultra Performance Liquid Chromatography technique (UPLC). The mutagenicity of AFMF at 4, 20, 50, 100, 200, 500, and 1000 µg/well was <2.0 in S. typhimurium and the induced micronucleated polychromatic and normochromatic erythrocytes at 500, 1000, 2000, and 4000 mg/kg were not significantly different from the negative control (p≥0.05). The mutagenic activity of benzo[a]pyrene and cyclophosphamide was significantly suppressed above 50.0% throughout the tested concentrations. Fifty percent of the free radicals from DPPH were scavenged by AFMF at 0.11 mg/ml. Total phenolic and flavonoid contents of AFMF were 51.0 mg GAE/g and 27 mg QE/g, respectively. Rutin was elucidated by the UPLC technique, and thereby suspected to be the phytochemical responsible for the observed antimutagenic activity. Thus far, AFMF seems to contain a promising chemotherapeutic agent for the prevention of genetic damage that is crucial for cancer development. PMID:25520963

  8. The effects of stainless steel finish on Salmonella Typhimurium attachment, biofilm formation and sensitivity to chlorine.

    PubMed

    Schlisselberg, Dov B; Yaron, Sima

    2013-08-01

    Bacterial colonization and biofilm formation on stainless steel (SS) surfaces can be sources for cross contamination in food processing facilities, possessing a great threat to public health and food quality. Here the aim was to demonstrate the influence of surface finish of AISI 316 SS on colonization, biofilm formation and susceptibility of Salmonella Typhimurium to disinfection. Initial attachment of S. Typhimurium on surfaces of SS was four times lower, when surface was polished by Bright-Alum (BA) or Electropolishing (EP), as compared to Mechanical Sanded (MS) or the untreated surface (NT). The correlation between roughness and initial bacterial attachment couldn't account on its own to explain differences seen. Biofilms with similar thickness (15-18 μm) were developed on all surfaces 1-day post inoculation, whereas EP was the least covered surface (23%). Following 5-days, biofilm thickness was lowest on EP and MS (30 μm) and highest on NT (62 μm) surfaces. An analysis of surface composition suggested a link between surface chemistry and biofilm development, where the higher concentrations of metal ions in EP and MS surfaces correlated with limited biofilm formation. Interestingly, disinfection of biofilms with chlorine was up to 130 times more effective on the EP surface (0.005% surviving) than on the other surfaces. Overall these results suggest that surface finish should be considered carefully in a food processing plant. PMID:23628616

  9. Characterization of anaerobic sulfite reduction by Salmonella typhimurium and purification of the anaerobically induced sulfite reductase

    SciTech Connect

    Hallenbeck, P.C. ); Clark, M.A.; Barrett, E.L. )

    1989-06-01

    Mutants of Salmonella typhimurium that lack the biosynthetic sulfite reductase (cysI and cysJ mutants) retain the ability to reduce sulfite for growth under anaerobic conditions. Here we report studies of sulfite reduction by a cysI mutant of S. typhimurium and purification of the associated anaerobic sulfite reductase. Sulfite reduction for anaerobic growth did not require a reducing atmosphere but was prevented by an argon atmosphere contaminated with air (<0.33%). It was also prevented by the presence of 0.1 mM nitrate. Anaerobic growth in liquid minimal medium, but not on agar, was found to require additions of trace amounts (10{sup {minus}7} M) of cysteine. Spontaneous mutants that grew under the argon contaminated with air also lost the requirement for 10{sup {minus}7}M cysteine for anaerobic growth in liquid. A role for sulfite reduction in anaerobic energy generation was contraindicated by the findings that sulfite reduction did not improve cell yields, and anaerobic sulfite reductase activity was greatest during the stationary phase of growth. Sulfite reductase was purified from the cytoplasmic fraction of the anaerobically grown cysI mutant and was purified 190-fold. The most effective donor in crude extracts was NADH. NADHP and methyl viologen were, respectively, 40 and 30% as effective as NADH. Oxygen reversibly inhibited the enzyme. The anaerobic sulfite reductase showed some resemblance to the biosynthetic sulfite reductase, but apparently it has a unique, as yet unidentified function.

  10. Rescuing chemotaxis of the anticancer agent Salmonella enterica serovar Typhimurium VNP20009.

    PubMed

    Broadway, Katherine M; Denson, Elizabeth A P; Jensen, Roderick V; Scharf, Birgit E

    2015-10-10

    The role of chemotaxis and motility in Salmonella enterica serovar Typhimurium tumor colonization remains unclear. We determined through swim plate assays that the well-established anticancer agent S. Typhimurium VNP20009 is deficient in chemotaxis, and that this phenotype is suppressible. Through genome sequencing, we revealed that VNP20009 and four selected suppressor mutants had a single nucleotide polymorphism (SNP) in cheY causing a mutation in the conserved proline residue at position 110. CheY is the response regulator that interacts with the flagellar motor-switch complex and modulates rotational bias. The four suppressor mutants additionally carried non-synonymous SNPs in fliM encoding a flagellar switch protein. The CheY-P110S mutation in VNP20009 likely rendered the protein unable to interact with FliM, a phenotype that could be suppressed by mutations in FliM. We replaced the mutated cheY in VNP20009 with the wild-type copy and chemotaxis was partially restored. The swim ring of the rescued strain, VNP20009 cheY(+), was 46% the size of the parental strain 14028 swim ring. When tested in capillary assays, VNP20009 cheY(+) was 69% efficient in chemotaxis towards the attractant aspartate as compared to 14028. Potential reasons for the lack of complete restoration and implications for bacterial tumor colonization will be discussed. PMID:26200833

  11. Stereoselectivity and stereospecificity of the alpha,beta-dihydroxyacid dehydratase from Salmonella typhimurium.

    PubMed

    Armstrong, F B; Muller, U S; Reary, J B; Whitehouse, D; Croute, D H

    1977-07-21

    1. In addition to the known 2R,3R- and 2R, 3S-2,3-dihydroxy-3-methylpentanoic acids (DHI), the 1S,3S- and sS,DR-isomers were prepared. 2S-2,3-Dihydroxy-3-methylbutanoic acid (DHV) was also prepared in addition to the known 2R-isomer. 2. The six dihydroxy acids were examined for their ability to promote the growth of isoleucine-valine (ilv)-requiring strains of Salmonella typhimurium and to serve as substrates for the alpha,beta-dihydroxyacid dehydratase of the same organism. 3. Only 2R,3R-2,3-dihydroxy-3-methylpentanoic and 2R-2,3-dihydroxy-3-methylbutanoic acids supported growth of the ilv strains of S. typhimurium. 4. alpha,beta-Dihydroxyacid dehydratase utilized the three isomers with the 2R-configuration as substrates but not those with the 2S-configuration. 5. In an additional growth study that utilized the 3R- and 3S-isomers of 3-methyl-2-oxopentanoic acid, the alpha-keto acid analogue of isoleucine, only the 3S-isomer supported growth. 6. It is concluded that the mechanism of action of the dehydratase is stereospecific in that the proton that is attached to C-3 of the substrate occupies the same steriochemical position as the departing hydroxyl group (Fig. 6). PMID:328058

  12. A network inference workflow applied to virulence-related processes in Salmonella typhimurium.

    PubMed

    Taylor, Ronald C; Singhal, Mudita; Weller, Jennifer; Khoshnevis, Saeed; Shi, Liang; McDermott, Jason

    2009-03-01

    Inference of the structure of mRNA transcriptional regulatory networks, protein regulatory or interaction networks, and protein activation/inactivation-based signal transduction networks are critical tasks in systems biology. In this article we discuss a workflow for the reconstruction of parts of the transcriptional regulatory network of the pathogenic bacterium Salmonella typhimurium based on the information contained in sets of microarray gene-expression data now available for that organism and describe our results obtained by following this workflow. The primary tool is one of the network-inference algorithms deployed in the Software Environment for Biological Network Inference (SEBINI). Specifically, we selected the algorithm called context likelihood of relatedness (CLR), which uses the mutual information contained in the gene-expression data to infer regulatory connections. The associated analysis pipeline automatically stores the inferred edges from the CLR runs within SEBINI and, upon request, transfers the inferred edges into either Cytoscape or the plug-in Collective Analysis of Biological Interaction Networks (CABIN) tool for further postanalysis of the inferred regulatory edges. The following article presents the outcome of this workflow, as well as the protocols followed for microarray data collection, data cleansing, and network inference. Our analysis revealed several interesting interactions, functional groups, metabolic pathways, and regulons in S. typhimurium. PMID:19348639

  13. Characterization of factor IIIGLc in catabolite repression-resistant (crr) mutants of Salmonella typhimurium.

    PubMed Central

    Scholte, B J; Schuitema, A R; Postma, P W

    1982-01-01

    crr mutants of Salmonella typhimurium are thought to be defective in the regulation of adenylate cyclase and a number of transport systems by the phosphoenolpyruvate-dependent sugar phosphotransferase system, crr mutants are also defective in the enzymatic activity of factor IIIGlc (IIIGlc), a protein component of the phosphotransferase system involved in glucose transport. Therefore, it has been proposed that IIIGlc is the primary effector of phosphotransferase system-mediated regulation of cell metabolism. We characterized crr mutants with respect to the presence and function of IIIGlc by using an immunochemical approach. All of the crr mutants tested had low (0 to 30%) levels of IIIGlc compared with wild-type cells, as determined by rocket immunoelectrophoresis. The IIIGlc isolated from one crr mutant was investigated in more detail and showed abnormal aggregation behavior, which indicated a structural change in the protein. These results supported the hypothesis that a crr mutation directly affects IIIGlc, probably by altering the structural gene of IIIGlc. Several crr strains which appeared to be devoid of IIIGlc in immunoprecipitation assays were still capable of in vitro phosphorylation and transport of methyl alpha-glucoside. This phosphorylation activity was sensitive to specific anti-IIIGlc serum. Moreover, the membranes of crr mutants, as well as those of wild-type cells, contained a protein that reacted strongly with our anti-IIIGlc serum. We propose that S. typhimurium contains a membrane-bound form of IIIGlc which may be involved in phosphotransferase system activity. Images PMID:7035434

  14. No Beneficial Effects Evident for Enterococcus faecium NCIMB 10415 in Weaned Pigs Infected with Salmonella enterica Serovar Typhimurium DT104

    PubMed Central

    Kreuzer, Susanne; Aßmus, Jens; Schmidt, Michael F. G.; Brockmann, Gudrun A.; Nöckler, Karsten

    2012-01-01

    Salmonella enterica serovar Typhimurium DT 104 is the major pathogen for salmonellosis outbreaks in Europe. We tested if the probiotic bacterium Enterococcus faecium NCIMB 10415 can prevent or alleviate salmonellosis. Therefore, piglets of the German Landrace breed that were treated with E. faecium (n = 16) as a feed additive and untreated controls (n = 16) were challenged with S. Typhimurium 10 days after weaning. The presence of salmonellae in feces and selected organs, as well as the immune response, were investigated. Piglets treated with E. faecium gained less weight than control piglets (P = 0.05). The feeding of E. faecium had no effect on the fecal shedding of salmonellae and resulted in a higher abundance of the pathogen in tonsils of all challenged animals. The specific (anti-Salmonella IgG) and nonspecific (haptoglobin) humoral immune responses as well as the cellular immune response (T helper cells, cytotoxic T cells, regulatory T cells, γδ T cells, and B cells) in the lymph nodes, Peyer's patches of different segments of the intestine (jejunal and ileocecal), the ileal papilla, and in the blood were affected in the course of time after infection (P < 0.05) but not by the E. faecium treatment. These results led to the conclusion that E. faecium may not have beneficial effects on the performance of weaned piglets in the case of S. Typhimurium infection. Therefore, we suggest a critical discussion and reconsideration of E. faecium NCIMB 10415 administration as a probiotic for pigs. PMID:22544257

  15. The small regulatory RNA molecule MicA is involved in Salmonella enterica serovar Typhimurium biofilm formation

    PubMed Central

    2010-01-01

    Background LuxS is the synthase enzyme of the quorum sensing signal AI-2. In Salmonella Typhimurium, it was previously shown that a luxS deletion mutant is impaired in biofilm formation. However, this phenotype could not be complemented by extracellular addition of quorum sensing signal molecules. Results Analysis of additional S. Typhimurium luxS mutants indicated that the LuxS enzyme itself is not a prerequisite for a wild type mature biofilm. However, in close proximity of the luxS coding sequence, a small RNA molecule, MicA, is encoded on the opposite DNA strand. Interference with the MicA expression level showed that a balanced MicA level is essential for mature Salmonella biofilm formation. Several MicA targets known to date have previously been reported to be implicated in biofilm formation in Salmonella or in other bacterial species. Additionally, we showed by RT-qPCR analysis that MicA levels are indeed altered in some luxS mutants, corresponding to their biofilm formation phenotype. Conclusions We show that the S. Typhimurium biofilm formation phenotype of a luxS mutant in which the complete coding region is deleted, is dependent on the sRNA molecule MicA, encoded in the luxS adjacent genomic region, rather than on LuxS itself. Future studies are required to fully elucidate the role of MicA in Salmonella biofilm formation. PMID:21044338

  16. Response of layer and broiler strain chickens to parenteral administration of a live Salmonella Typhimurium vaccine.

    PubMed

    Groves, Peter J; Sharpe, Sue M; Cox, Julian M

    2015-07-01

    Responses to the parenteral administration of a live aroA deletion Salmonella serovar Typhimurium vaccine given to three brown egg layer strains and two broiler strains were studied. Twenty-five birds of each strain were reared together in floor pens to 6 weeks of age and then moved as individual strains to new floor pens and injected with 10(8) colony forming units (CFU) per bird of the vaccine bacteria intramuscularly or subcutaneously, 10(6) CFU per bird subcutaneously, or phosphate buffered saline (PBS) subcutaneously as a vaccination control. Three birds of one layer strain were injected intramuscularly with 0.5mg/ bird S. Typhimurium lipopolysaccharide (LPS) to evaluate whether response was similar for vaccine and endotoxin. Birds were weighed, and rectal temperatures recorded at the time of injection, then observed over 24 hours. Rectal temperatures were measured and blood samples collected for serum IL-6 assay at 3 hours post injection (PI). At 12 hours PI blood samples were drawn for analyses for plasma phosphorus (P), glucose (Glu), cholesterol (Cho), aspartate transaminase (AST), total protein (Ptn) and creatinine kinase (CK). Blood was sampled 14 days PI and tested for serum antibody to S. Typhimurium. Vaccination resulted in significant seroconversion by 14 days PI in all strains compared to the controls. The three layer strains exhibited a clinical malaise, evident within 90 minutes of injection, lasting for 12 hours, with complete recovery by 24 hours PI. Only the 10(8) CFU dose given subcutaneously produced an increase in rectal temperature 3 hours PI. Vaccination had no effect on IL-6 or Ptn. All vaccine doses increased P and the higher dose by either route decreased Cho in all bird strains. The 10(8) vaccine dose increased Glu and intramuscular injection markedly elevated CK only in the layer strains. The response was not completely congruous with that to LPS alone. The results highlight the need for consideration of differences in response of

  17. Infection with Salmonella typhimurium modulates the immune response to Schistosoma mansoni glutathione-S-transferase.

    PubMed Central

    Comoy, E E; Vendeville, C; Capron, A; Thyphronitis, G

    1997-01-01

    Immune response polarization is controlled by several factors, including cytokines, antigen-presenting cells, antigen dose, and others. We have previously shown that adjuvants and live vectors play a critical role in polarization. Thus, immunization with the Schistosoma mansoni 28-kDa glutathione-S-transferase (Sm28-GST) in aluminum hydroxide induced a type 2 cytokine profile and the production of immunoglobulin G1 (IgG1)- and IgE-specific antibodies. In contrast, mice infected with recombinant Salmonella typhimurium expressing Sm28-GST developed a type 1 cytokine profile and produced IgG2a-specific antibodies against Sm28-GST and Salmonella antigens. In this study, to determine if S. typhimurium not expressing Sm28-GST would still influence the type of the response against this antigen, we compared the profiles of the immune responses generated against Sm28-GST administered in alum in mice infected and not infected with S. typhimurium. Infected mice generated both IgG1 and IgG2a antibodies against Sm28-GST, while noninfected mice produced only IgG1 anti-Sm28-GST antibodies. Moreover, interleukin-4 (IL-4) mRNA expression in infected mice was near background levels, while gamma interferon (IFN-gamma) mRNA expression in coinfected mice was significantly higher than in mice immunized with Sm28-GST in alum only. However, after antigen-specific stimulation in vitro with Sm28-GST, levels of IL-4 and IFN-gamma cytokine production were similar in the two groups of mice. These results suggest that (i) the immune milieu produced during an infection may modify the response against an irrelevant antigen and (ii) isotype switching may be influenced by the cytokine environment of a bystander immune response, even though the specific antigen-driven cytokine production is not modified. Thus, the isotypic profile is not always an absolute reflection of the cytokines produced by antigen-specific Th cells. PMID:9234784

  18. H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing

    PubMed Central

    Brunet, Yannick R.; Khodr, Ahmad; Logger, Laureen; Aussel, Laurent; Mignot, Tâm; Rimsky, Sylvie

    2015-01-01

    The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection. PMID:25916986

  19. H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing.

    PubMed

    Brunet, Yannick R; Khodr, Ahmad; Logger, Laureen; Aussel, Laurent; Mignot, Tâm; Rimsky, Sylvie; Cascales, Eric

    2015-07-01

    The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection. PMID:25916986

  20. 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

  1. Transcriptional activity of the transposable element Tn10 in the Salmonella typhimurium ilvGEDA operon.

    PubMed

    Blazey, D L; Burns, R O

    1982-08-01

    Polarity of Tn10 insertion mutations in the Salmonella typhimurium ilvGEDA operon depends on both the location and the orientation of the Tn10 element. One orientation of Tn10 insertions in ilvG and ilvE permits low-level expression of the downstream ilvEDA and ilvDA genes, respectively. Our analysis of Salmonella ilv recombinant plasmids shows that this residual ilv expression must result from Tn10-directed transcription and does not reflect the presence of internal promoters in the ilvGEDA operon, as was previously suggested. The opposite orientation of Tn10 insertion in ilvE prevents ilvDA expression, indicating that only one end of Tn10 is normally active in transcribing adjacent genes. Both orientations of Tn10 insertion in ilvD exert absolute polarity on ilvA expression. Expression of ilvA is known to be dependent on effective translation of ilvD, perhaps reflecting the lack of a ribosome binding site proximal to the ilvA sequence. Therefore, recognition of the ability of Tn10 to promote transcription of contiguous genes in the ilvGEDA operon apparently requires the presence of associated ribosome binding sites. PMID:6289328

  2. Assessing Salmonella typhimurium persistence in poultry carcasses under multiple thermal conditions consistent with composting and wet rendering.

    PubMed

    Vaddella, V; Pitesky, M; Cao, W; Govinthasamy, V; Shi, J; Pandey, P

    2016-03-01

    Mitigation of Salmonella associated with poultry carcasses is primarily accomplished by rendering or carcass composting. While rendering temperatures and pressures are well established for pathogen inactivation in poultry carcasses, parameters controlling composting processes are less defined in part because multiple conditions and procedures are utilized. Consequently, limited knowledge exists describing the impacts of composting with varying temperature and mixing protocols with respect to the inactivation of Salmonella in poultry carcasses. To improve the existing knowledge of Salmonella survival in poultry carcasses, inactivation of Salmonella enterica serovar Typhimurium (ST) LT2 was investigated. The impacts of various composting temperatures (55, 62.5°C) and low-rendering (i.e., pasteurization) temperatures (70, 78°C) on Salmonella inactivation were tested in a bench-top setting using a ground carcass slurry and whole birds under mixed and non-mixed conditions. Results showed that the ground carcass slurry and the whole carcass exposed to temperatures consistent with composting had no detectable Salmonella after 110 h with a level of detection of one CFU/mL of ground carcass slurry and one CFU/g of whole carcasses, respectively. In addition, grinding of carcasses as opposed to whole carcasses was more predictable with respect to Salmonella heat inactivation. Furthermore, results showed that constant mixing decreased the overall time required to eliminate Salmonella under composting and low-rendering temperatures. PMID:26769271

  3. Salmonella enterica Serovars Typhi and Paratyphi A are avirulent in newborn and infant mice even when expressing virulence plasmid genes of Salmonella Typhimurium

    PubMed Central

    Javier Santander, M.; Curtiss, Roy

    2014-01-01

    Background Salmonella enterica serovars Typhi and Paratyphi A are human host-restricted pathogens. Therefore, there is no small susceptible animal host that can be used to assess the virulence and safety of vaccine strains derived from these Salmonella serovars. However, infant mice have been used to evaluate virulence and colonization by another human host-restricted pathogen, Vibrio cholerae. Methodology The possibility that infant mice host could be adapted for Salmonella led us to investigate the susceptibility of newborn and infant mice to oral infection with S. Typhi and S. Paratyphi A. Salmonella enterica serovar Typhimurium causes enteric fever in adult mice and this system has been used as a model for human typhoid. The pSTV virulence plasmid, not present in S. Typhi and S. Paratyphi A, plays an essential role in S. Typhimurium colonization and systemic infection of mice. We also conjugated pSTV into S. Typhi and S. Paratyphi A serovars and evaluated these transconjugants in newborn and infant mice. Results We determined that the spv virulence genes from the S. Typhimurium virulence plasmid are expressed in S. Typhi and S. Paratyphi A in a RpoS dependent fashion. Also, we determined that S. Typhi and S. Paratyphi A with and without pSTV transiently colonize newborn and infant mice tissues. Conclusion Newborn and infant mice infected with S. Typhi and S. Paratyphi A do not succumb to the infection and that carriage of the S. Typhimurium virulence plasmid, pSTV, did not influence these results. PMID:21252450

  4. Dormant intracellular Salmonella enterica serovar Typhimurium discriminates among Salmonella pathogenicity island 2 effectors to persist inside fibroblasts.

    PubMed

    Núñez-Hernández, Cristina; Alonso, Ana; Pucciarelli, M Graciela; Casadesús, Josep; García-del Portillo, Francisco

    2014-01-01

    Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that the S. enterica serovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations. PMID:24144726

  5. Effects of irradiation and fumaric acid treatment on the inactivation of Listeria monocytogenes and Salmonella typhimurium inoculated on sliced ham

    NASA Astrophysics Data System (ADS)

    Song, Hyeon-Jeong; Lee, Ji-Hye; Song, Kyung Bin

    2011-11-01

    To examine the effects of fumaric acid and electron beam irradiation on the inactivation of foodborne pathogens in ready-to-eat meat products, sliced ham was inoculated with Listeria monocytogenes and Salmonella typhimurium. The inoculated ham slices were treated with 0.5% fumaric acid or electron beam irradiation at 2 kGy. Fumaric acid treatment reduced the populations of L. monocytogenes and S. typhimurium by approximately 1 log CFU/g compared to control populations. In contrast, electron beam irradiation decreased the populations of S. typhimurium and L. monocytogenes by 3.78 and 2.42 log CFU/g, respectively. These results suggest that electron beam irradiation is a better and appropriate technique for improving the microbial safety of sliced ham.

  6. Inhibition of Salmonella typhimurium by medium-chain fatty acids in an in vitro simulation of the porcine cecum.

    PubMed

    Messens, Winy; Goris, Johan; Dierick, Noël; Herman, Lieve; Heyndrickx, Marc

    2010-02-24

    Salmonella typhimurium was responsible for more than half of the reported cases of human salmonellosis in Belgium in 2007 and was the predominant serovar isolated from slaughter pig carcasses. To lower the Salmonella contamination of pork meat, measures can be taken at the primary production level, e.g. by reducing the shedding of Salmonella through the use of feed additives such as medium-chain fatty acids (MCFAs). An in vitro continuous culture system, simulating the porcine cecum, was developed for investigating the effect of MCFAs (sodium caproate, sodium caprylate and sodium caprinate) on the pig intestinal microbial community. The system was monitored by plating on selective media, PCR-DGGE and HPLC analysis of fermentation products. An inoculated S. typhimurium strain could be maintained by the system at a population size of about 5 log(10)cfu/mL. By the addition of 15 mM caprylate, significant reductions of coliforms and Salmonella counts by 4.69 log(10) units (95% confidence interval: 4.19-5.18) could be achieved, while other bacterial populations were clearly less affected. This concentration seems economically feasible in pig feed, provided that the substance can reach the cecum without being absorbed. Thus, caprylate, for example in the form of encapsulated beads or as triacylglycerol oil, might have potential as a Salmonella-reducing additive in pig feed. PMID:19709819

  7. Glutathione: an intracellular and extracellular protective agent in Salmonella typhimurium and Escherichia coli

    SciTech Connect

    Owens, R.A.

    1986-01-01

    Levels of glutathione, were measured in several aerobically grown strains of Salmonella typhimurium and Escherichia coli. External accumulation of GSH was inhibited by 30 mM NaN/sub 3/. Thus, GSH export may be energy dependent. Greater than 50% of the glutathione detected in the media was in the reduced form. Since the oxidized glutathione in the media could be accounted for by oxidation during aerobic incubation as well as in sample processing, the glutathione was predominantly exported in the reduced form. Extracellular glutathione was detected in log phase cultures of 2 out of 2 E. coli strains and 6 of 8 Salmonella strains tested. Two-dimensional paper chromatography of supernatants from cultures labelled with Na/sub 2//sup 35/SO/sub 4/ confirmed the presence of GSH and revealed five other sulfur-containing compounds in the media of Salmonella and E. coli cultures. Since media from cultures of an E. coli GSH/sup -/ strain contained compounds with identical R/sub f/'s, the five unidentified compounds were not derivatives of GSH. The addition of 26 ..mu..M GSH to cultures of TA1534 partially protected the bacteria from the toxic effects of 54 ..mu..M N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). When MNNG was preincubated with equimolar GSH, the mutagenicity of the MNNG was neutralized. The addition of micromolar GSH to cultures and E. coli GSH/sup -/ strain protected the cells from growth inhibition by micromolar concentrations of mercuric chloride, silver nitrate, cisplatin, cadmium chloride, and iodoacetamide. The data presented demonstrate that micromolar concentrations of external GSH can significantly shorten the recovery time of cells after exposure to toxic agents in the environment.

  8. Effect of grinding intensity and feed physical form on in vitro adhesion of Salmonella Typhimurium and mannose residues in intestinal mucus receptors for salmonellae.

    PubMed

    Callies, A; Sander, S J; Verspohl, J; Beineke, A; Kamphues, J

    2012-12-01

    The hypothesis of this study was that feeding a fine, pelleted diet (FP) compared to a coarse meal diet (CM) results in a higher mannose content in the intestinal mucus of pigs and therefore an increased in vitro adhesion of Salmonella Typhimurium DT104 L to the mucus. The 2 diets were fed to a total of 24 weaned pigs for 6 wk after which mannose content in the mucus was evaluated histochemically using the α1-3-d-mannose-specific lectin Galanthus nivalis agglutinin. The crypt width was determined as an indirect measure for the amount of secreted mucus. Ileal and cecal tissue samples were incubated with approximately 7.77 × 10(7) cfu Salmonella Typhimurium and numbers of salmonellae adhering to the mucus and/or mucosa were determined by culture techniques. There was no effect of feed physical form on the in vitro adhesion of S. Typhimurium either in the ileum (7.1 ± 0.19 log(10) cfu/g tissue) or in the cecum (6.8 ± 0.26 log(10) cfu/g). The mannose content of the mucus also did not differ between the treatment groups. The crypts of the duodenum, jejunum, and cecum were wider (P < 0.05) after feeding the CM diet. This might be an indication for a higher mucus production in these pigs. PMID:23365353

  9. The architecture and ppGpp-dependent expression of the primary transcriptome of Salmonella Typhimurium during invasion gene expression

    PubMed Central

    2012-01-01

    Background Invasion of intestinal epithelial cells by Salmonella enterica serovar Typhimurium (S. Typhimurium) requires expression of the extracellular virulence gene expression programme (STEX), activation of which is dependent on the signalling molecule guanosine tetraphosphate (ppGpp). Recently, next-generation transcriptomics (RNA-seq) has revealed the unexpected complexity of bacterial transcriptomes and in this report we use differential RNA sequencing (dRNA-seq) to define the high-resolution transcriptomic architecture of wild-type S. Typhimurium and a ppGpp null strain under growth conditions which model STEX. In doing so we show that ppGpp plays a much wider role in regulating the S. Typhimurium STEX primary transcriptome than previously recognised. Results Here we report the precise mapping of transcriptional start sites (TSSs) for 78% of the S. Typhimurium open reading frames (ORFs). The TSS mapping enabled a genome-wide promoter analysis resulting in the prediction of 169 alternative sigma factor binding sites, and the prediction of the structure of 625 operons. We also report the discovery of 55 new candidate small RNAs (sRNAs) and 302 candidate antisense RNAs (asRNAs). We discovered 32 ppGpp-dependent alternative TSSs and determined the extent and level of ppGpp-dependent coding and non-coding transcription. We found that 34% and 20% of coding and non-coding RNA transcription respectively was ppGpp-dependent under these growth conditions, adding a further dimension to the role of this remarkable small regulatory molecule in enabling rapid adaptation to the infective environment. Conclusions The transcriptional architecture of S. Typhimurium and finer definition of the key role ppGpp plays in regulating Salmonella coding and non-coding transcription should promote the understanding of gene regulation in this important food borne pathogen and act as a resource for future research. PMID:22251276

  10. Salmonella enterica Serovar Typhimurium ompS1 and ompS2 Mutants Are Attenuated for Virulence in Mice

    PubMed Central

    Rodríguez-Morales, Olivia; Fernández-Mora, Marcos; Hernández-Lucas, Ismael; Vázquez, Alejandra; Puente, José Luis; Calva, Edmundo

    2006-01-01

    Salmonella enterica serovar Typhimurium mutants with mutations in the ompS1 and ompS2 genes, which code for quiescent porins, were nevertheless highly attenuated for virulence in a mouse model, indicating a role in pathogenesis. Similarly, a strain with a mutation in the gene coding for LeuO, a positive regulator of ompS2, was also attenuated. PMID:16428792

  11. The Small RNA DsrA Influences the Acid Tolerance Response and Virulence of Salmonella enterica Serovar Typhimurium

    PubMed Central

    Ryan, Daniel; Ojha, Urmesh K.; Jaiswal, Sangeeta; Padhi, Chandrashekhar; Suar, Mrutyunjay

    2016-01-01

    The Gram-negative, enteropathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) is exposed to various stress conditions during pathogenesis, of which acid stress serves as a major defense mechanism in the host. Such environments are encountered in the stomach and Salmonella containing vacuole of phagocytic and non-phagocytic cells. It is only recently that small RNAs (sRNAs) have come to the forefront as major regulators of stress response networks. Consequently, the sRNA DsrA which regulates acid resistance in Escherichia coli, has not been characterized in the acid tolerance response (ATR) of Salmonella. In this study, we show dsrA to be induced two and threefold under adaptation and challenge phases of the ATR, respectively. Additionally, an isogenic mutant lacking dsrA (ΔDsrA) displayed lower viability under the ATR along with reduced motility, feeble adhesion and defective invasion efficacy in vitro. Expression analysis revealed down regulation of several Salmonella pathogenicity island-1 (SPI-1) effectors in ΔDsrA compared to the wild-type, under SPI-1 inducing conditions. Additionally, our in vivo data revealed ΔDsrA to be unable to cause gut inflammation in C57BL/6 mice at 72 h post infection, although intracellular survival and systemic dissemination remained unaffected. A possible explanation may be the significantly reduced expression of flagellin structural genes fliC and fljB in ΔDsrA, which have been implicated as major proinflammatory determinants. This study serves to highlight the role of sRNAs such as DsrA in both acid tolerance and virulence of S. Typhimurium. Additionally the robust phenotype of non-invasiveness could be exploited in developing SPI-I attenuated S. Typhimurium strains without disrupting SPI-I genes. PMID:27199929

  12. Inactivation of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhimurium with compounds available in households.

    PubMed

    Yang, Hua; Kendall, Patricia A; Medeiros, Lydia; Sofos, John N

    2009-06-01

    Solutions of selected household products were tested for their effectiveness against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium. Hydrogen peroxide (1.5 and 3%), vinegar (2.5 and 5% acetic acid), baking soda (11, 33, and 50% sodium bicarbonate), household bleach (0.0314, 0.0933, and 0.670% sodium hypochlorite), 5% acetic acid (prepared from glacial acetic acid), and 5% citric acid solutions were tested against the three pathogens individually (five-strain composites of each, 10(8) CFU/ml) by using a modified AOAC International suspension test at initial temperatures of 25 and 55degrees C for 1 and 10 min. All bleach solutions (pH 8.36 to 10.14) produced a >5-log reduction of all pathogens tested after 1 min at 25 degrees C, whereas all baking soda solutions (pH 7.32 to 7.55) were ineffective (<1-log reduction) even after 10 min at an initial temperature of 55 degrees C. After 1 min at 25 degrees C, 3% hydrogen peroxide (pH 2.75) achieved a >5-log reduction of both Salmonella Typhimurium and E. coli O157:H7, whereas undiluted vinegar (pH 2.58) had a similar effect only against Salmonella Typhimurium. Compared with 1 min at 25 degrees C, greater reductions of L. monocytogenes (P < 0.05) were obtained with all organic acid and hydrogen peroxide treatments after 10 min at an initial temperature of 55 degrees C. The efficacies of household compounds against all tested pathogens decreased in the following order: 0.0314% sodium hypochlorite > 3% hydrogen peroxide > undiluted vinegar and 5% acetic acid > 5% citric acid > baking soda (50% sodium bicarbonate). The sensitivity of the tested pathogens to all tested household compounds followed the sequence of Salmonella Typhimurium > E. coli O157: H7 > L. monocytogenes. PMID:19610330

  13. Investigation and management of an outbreak of Salmonella Typhimurium DT8 associated with duck eggs, Ireland 2009 to 2011.

    PubMed

    Garvey, P; McKeown, P; Kelly, P; Cormican, M; Anderson, W; Flack, A; Barron, S; De Lappe, N; Buckley, J; Cosgrove, C; Molloy, D; O' Connor, J; O' Sullivan, P; Matthews, J; Ward, M; Breslin, A; O' Sullivan, M B; Kelleher, K; McNamara, A; Foley-Nolan, C; Pelly, H; Cloak, F

    2013-01-01

    Salmonella Typhimurium DT8 was a very rare cause of human illness in Ireland between 2000 and 2008, with only four human isolates from three patients being identified. Over a 19-month period between August 2009 and February 2011, 34 confirmed cases and one probable case of Salmonella Typhimurium DT8 were detected, all of which had an MLVA pattern 2-10-NA-12-212 or a closely related pattern. The epidemiological investigations strongly supported a linkbetween illness and exposure to duck eggs. Moreover, S. Typhimurium with an MLVA pattern indistinguishable (or closely related) to the isolates from human cases, was identified in 22 commercial and backyard duck flocks, twelve of which were linked with known human cases. A range of control measures were taken at farm level, and advice was provided to consumers on the hygienic handling and cooking of duck eggs. Although no definitive link was established with a concurrent duck egg-related outbreak of S. Typhimurium DT8 in the United Kingdom, it seems likely that the two events were related. It may be appropriate for other countries with a tradition of consuming duck eggs to consider the need for measures to reduce the risk of similar outbreaks. PMID:23611032

  14. Differences in Salmonella enterica serovar Typhimurium strain invasiveness are associated with heterogeneity in SPI-1 gene expression

    PubMed Central

    Clark, Leann; Perrett, Charlotte A.; Malt, Layla; Harward, Caryn; Humphrey, Suzanne; Jepson, Katy A.; Martinez-Argudo, Isabel; Carney, Laura J.; La Ragione, Roberto M.; Humphrey, Tom J.

    2011-01-01

    Most studies on Salmonella enterica serovar Typhimurium infection focus on strains ATCC SL1344 or NTCC 12023 (ATCC 14028). We have compared the abilities of these strains to induce membrane ruffles and invade epithelial cells. S. Typhimurium strain 12023 is less invasive and induces smaller membrane ruffles on MDCK cells compared with SL1344. Since the SPI-1 effector SopE is present in SL1344 and absent from 12023, and SL1344 sopE mutants have reduced invasiveness, we investigated whether 12023 is less invasive due to the absence of SopE. However, comparison of SopE+ and SopE− S. Typhimurium strains, sopE deletion mutants and 12023 expressing a sopE plasmid revealed no consistent relationship between SopE status and relative invasiveness. Nevertheless, absence of SopE was closely correlated with reduced size of membrane ruffles. A PprgH–gfp reporter revealed that relatively few of the 12023 population (and that of the equivalent strain ATCC 14028) express SPI-1 compared to other S. Typhimurium strains. Expression of a PhilA–gfp reporter mirrored that of PprgH–gfp in 12023 and SL1344, implicating reduced signalling via the transcription factor HilA in the heterogeneous SPI-1 expression of these strains. The previously unrecognized strain heterogeneity in SPI-1 expression and invasiveness has important implications for studies of Salmonella infection. PMID:21493681

  15. Cellular changes and cytokine expression in the ilea of gnotobiotic piglets resulting from peroral Salmonella typhimurium challenge.

    PubMed Central

    Trebichavský, I; Dlabac, V; Reháková, Z; Zahradnícková, M; Splíchal, I

    1997-01-01

    Two stable rough mutants of Salmonella spp. were studied as live peroral vaccines. The SF1591 mutant of S. typhimurium (Ra chemotype) protected germ-free piglets against subsequent infection with virulent smooth S. typhimurium LT2, whereas a deep-rough mutant of S. minnesota mR595 (Re chemotype) did not. We investigated cytokine and leukocyte profiles in the ilea of gnotobiotic piglets colonized for 1 week either with rough mutants alone or with rough mutants followed by S. typhimurium LT2. The ileal mucosae of piglets associated with strain SF1591 alone were not inflamed. Villi contained activated macrophages, and enterocytes expressed transforming growth factor beta (TGF-beta). Subsequent infection of piglets with S. typhimurium LT2 resulted in immigration of alphabeta T cells and immunoglobulin A (IgA) response. In contrast, the ileal mucosae of piglets associated with strain mR595 alone expressed heat shock proteins and inflammatory cytokines but not TGF-beta. Acellular villi contained numerous gammadelta T cells but no alphabeta T cells. After subsequent challenge with the LT2 strain, most piglets died of sepsis. Intestinal mucosae contained IgG but no IgA. These findings suggest the importance of cytokine signals in the regulation of intestinal responses against Salmonella infection. PMID:9393822

  16. 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

  17. RNA-seq analysis of prophage induction in multidrug-resistant salmonella enterica serovar typhimurium DT104 following exposure to the agricultural antibiotic carbadox

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  19. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  20. Evaluation of the addition of charcoals to broiler diets on the recovery of Salmonella Typhimurium during grow-out and processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two experiments evaluated prebiotics added to feed on the recovery of Salmonella in broilers during grow-out and processing. In experiment 1, "seeder" chicks were inoculated with Salmonella Typhimurium and placed with penmates. Treatments were: basal control, 0.3% bamboo charcoal, 0.6% bamboo charco...

  1. Complete Genome Sequence of Salmonella enterica Serovar Typhimurium Strain SO3 (Sequence Type 302) Isolated from a Baby with Meningitis in Mexico

    PubMed Central

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

    2016-01-01

    The complete genome of Salmonella enterica serovar Typhimurium strain SO3 (sequence type 302), isolated from a fatal meningitis infection in Mexico, was determined using PacBio technology. The chromosome hosts six complete prophages and is predicted to harbor 51 genomic islands, including 13 pathogenicity islands (SPIs). It carries the Salmonella virulence plasmid (pSTV). PMID:27103717

  2. Salmonella enterica serovar Typhimurium strain lacking pmrG-HM-D provides excellent protection against salmonellosis in murine typhoid model.

    PubMed

    Negi, Vidya Devi; Singhamahapatra, Santanu; Chakravortty, Dipshikha

    2007-07-20

    The superiority of live attenuated vaccines in systemic salmonellosis has been proven over killed and subunit vaccines, because of its ability to induce protective cell mediated immunity by CD8+ T cells. A live attenuated Salmonella enterica serovar Typhimurium vaccine has been developed by systematic site directed deletion of the pmrG-HM-D chromosomal genomic loci. This gene confers involved in antimicrobial peptide resistance and is involved in LPS modification, both of which are the major immune evasive mechanisms in Salmonella. The efficacy of the newly developed strain in inducing protection against mortality after challenge with the virulent wild type Salmonella typhimurium 12023 was evaluated in mice model of typhoid fever. Animals were immunized and then boosted on days 7 and 14. Following challenge with virulent S. typhimurium 12023, organ burden and mortality of vaccinated mice were less compared to non-immunized controls. The vaccine strain also induced elevated CD8+ T cells in the vaccinated mice. This multiple mutant vaccine candidate appears to be safe for use in pregnant mice and provides a model for the development of live vaccine candidates against naturally occurring salmonellosis and typhoid fever. PMID:17574312

  3. The effect of feeding diets containing permitted antibiotics on the faecal excretion of Salmonella typhimurium by experimentally infected chickens.

    PubMed Central

    Smith, H. W.; Tucker, J. F.

    1975-01-01

    Groups of 45 chickens were fed continuously on diets containing 10 or 100 mg./kg. of different 'growth-promoting' antibiotics and infected orally with a nalidixic acid-resistant mutant of Salmonella typhimurium. The amount of S. typhimurium organisms excreted in their faeces was estimated by culturing them at weekly intervals and in a standard manner on plates of brilliant green agar containing sodium nalidixate, both direct and after enrichment in selenite broth. All of four groups fed diets containing 100 mg./kg. of nitrovin in three different experiments excreted much larger amounts of S. typhimurium than did groups fed antibiotic-free diets. In some, but not all, experiments, larger amounts were also excreted by groups fed diets containing 10 mg./kg. of nitrovin or 10 or 100 mg./kg. of flavomycin or tylosin. Feeding diets containing 10 or 100 mg./kg. of virginiamycin or bacitracin either did not influence or slightly increased the amount of S. typhimiurium excreted. Two groups fed continuously on diets containing 100 or 500 mg./kg. of sulphaquinoxaline for 44 days excreted smaller amounts of the S. typhimurium organisms that did groups fed antibiotic-free diets; no sulphonamide-resistant organisms of the S. typhimurium strain were isolated from the faeces. PMID:1100715

  4. Genome and Transcriptome Adaptation Accompanying Emergence of the Definitive Type 2 Host-Restricted Salmonella enterica Serovar Typhimurium Pathovar

    PubMed Central

    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

    2013-01-01

    ABSTRACT 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. PMID:23982073

  5. Effect of five cycle rapid freeze-thaw treatment in conjunction with various chemicals for the reduction of Salmonella typhimurium.

    PubMed

    Olson, V M; Swaminathan, B; Pratt, D E; Stadelman, W J

    1981-08-01

    A five cycle rapid freeze-rapid thaw process was used in conjunction with chemicals to reduce numbers of Salmonella typhimurium cells on poultry meat. The second portion of chicken wings consisting of ulna and radius with attached skin and muscle was inoculated with 400 to 900 colony forming units (CFU/g) of a nalidixic acid resistant strain of S. typhimurium. Chemicals used were 20 ppm chlorine, 5% potassium sorbate, 5% lactic acid, and 5% calcium propionate. The wings were either sprayed with or dipped into all chemicals before the freeze-thaw process. Wings were also chemically treated and not subjected to the freeze-thaw process. Numbers of S. typhimurium were determined by the most probable number procedure. The relative effectiveness of combinations of chemicals and the freeze-thaw process was compared to a control with the following percentage reductions of numbers of S. typhimurium cells: lactic acid, 98%; calcium propionate, 96%; potassium sorbate, 96%; chlorine, 95%; and freeze-thaw process without chemicals, 95%. There were no statistically significant differences among the treatments. In pilot plant study simulating commercial conditions, a carbon dioxide freezer was used for the rapid freeze and a microwave oven was used for the rapid thaw. Treatment of wings with 5% lactic acid plus freeze-thaw process resulted in statistically significant fewer numbers of S. typhimurium cells when compared to the freeze-thaw process without chemical treatment or to wings chemically treated without the freeze-thaw process. PMID:7322982

  6. Gold nanoparticle-DNA aptamer conjugate-assisted delivery of antimicrobial peptide effectively eliminates intracellular Salmonella enterica serovar Typhimurium.

    PubMed

    Yeom, Ji-Hyun; Lee, Boeun; Kim, Daeyoung; Lee, Jong-Kook; Kim, Suk; Bae, Jeehyeon; Park, Yoonkyung; Lee, Kangseok

    2016-10-01

    Antimicrobial peptides (AMPs) are a promising new class of antibacterial compounds. However, their applications in the treatment of intracellular pathogenic bacteria have been limited by their in vivo instability and low penetrating ability into mammalian cells. Here, we report that gold nanoparticles conjugated with DNA aptamer (AuNP-Apt) efficiently delivered AMPs into mammalian living systems with enhanced stability of the AMPs. C-terminally hexahistidine-tagged A3-APO (A3-APO(His)) AMPs were loaded onto AuNPs conjugated with His-tag DNA aptamer (AuNP-Apt(His)) by simple mixing and were delivered into Salmonella enterica serovar Typhimurium (S. Typhimurium)-infected HeLa cells, resulting in the increased viability of host cells due to the elimination of intracellular S. Typhimurium cells. Furthermore, the intravenous injection of AuNP-Apt(His) loaded with A3-APO(His) into S. Typhimurium-infected mice resulted in a complete inhibition of S. Typhimurium colonization in the mice organs, leading to 100% survival of the mice. Therefore, AuNP-Apt(His) can serve as an innovative platform for AMP therapeutics to treat intracellular bacterial infections in mammals. PMID:27424215

  7. Salmonella typhimurium induces epithelial IL-8 expression via Ca2+-mediated activation of the NF-κB pathway

    PubMed Central

    Gewirtz, Andrew T.; Rao, Anjali S.; Simon, Peter O.; Merlin, Didier; Carnes, Denice; Madara, James L.; Neish, Andrew S.

    2000-01-01

    Interactions between the enteric pathogen Salmonella typhimurium and the luminal surface of the intestine provoke an acute inflammatory response, mediated in part by epithelial cell secretion of the chemokine IL-8 and other proinflammatory molecules. This study investigated the mechanism by which this pathogen induces IL-8 secretion in physiologically polarized model intestinal epithelia. IL-8 secretion induced by both the prototypical proinflammatory cytokine TNF-α and S. typhimurium was NF-κB dependent. However, NF-κB activation and IL-8 secretion induced by S. typhimurium, but not by TNF-α, was preceded by and required an increase in intracellular [Ca2+]. Additionally, agonists that increased intracellular [Ca2+] by receptor-dependent (carbachol) or independent (thapsigargin, ionomycin) means also induced IL-8 secretion. Furthermore, the ability of S. typhimurium mutants to induce IκB-α degradation, NF-κB translocation, and IL-8 transcription and secretion correlated precisely with their ability to induce an intracellular [Ca2+] increase in model intestinal epithelia, but not with their ability to invade these cells. Finally, S. typhimurium, but not TNF-α, induced a Ca2+-dependent phosphorylation of IκB-α. These results indicate that S. typhimurium–induced activation of NF-κB–dependent epithelial inflammatory responses proceeds by a Ca2+-mediated activation of an IκB-α kinase. These observations raise the possibility that pharmacologic intervention of the acute inflammatory response can be selectively matched to the specific class of initiating event. PMID:10619864

  8. Intracellular survival of wild-type Salmonella typhimurium and macrophage-sensitive mutants in diverse populations of macrophages.

    PubMed

    Buchmeier, N A; Heffron, F

    1989-01-01

    Salmonella typhimurium survives within macrophages and causes a fatal infection in susceptible strains of mice. A number of S. typhimurium mutants that contain Tn10 insertions in genes which are necessary for survival within the macrophage have been isolated. To demonstrate the importance of each gene in intracellular survival, the mutations were transduced into a smooth-strain background and the ability to survive intracellularly was assayed in five different populations of macrophages. The majority of the original macrophage-sensitive mutants retained the macrophage-sensitive phenotype in the smooth-strain background. The ability to survive or grow within macrophages varied with both the source of macrophages and the individual mutants. S. typhimurium grew best in the macrophage-like cell line J774, survived at moderate levels in splenic and bone marrow-derived macrophages, and was killed most efficiently in peritoneal macrophages. Macrophage-sensitive mutants transduced into a smooth background were also less virulent than the parent, with a 50% lethal dose of 2 to 5 logs greater than that of the parental strain. These experiments demonstrate that survival of S. typhimurium within macrophages varies with the source of cells, with a distinct ability to survive in macrophages from mouse spleens, where S. typhimurium grows rapidly. These experiments also demonstrate the heterogeneity in intracellular survival among the various macrophage-sensitive mutants, which may reflect the relative importance of the individual mutated genes in survival within macrophages. PMID:2642463

  9. Differential innate immune responses of bovine peripheral blood leukocytes to Salmonella enterica serovars Dublin, Typhimurium, and Enteritidis.

    PubMed

    Pan, Deng; Rostagno, Marcos H; Ebner, Paul D; Eicher, Susan D

    2015-05-15

    The majority of Salmonella serovars cause no clinical disease in cattle, while some are associated with severe disease. The objective of the current study was to determine the innate immune responses of bovine peripheral blood leukocytes exposed to Salmonella enterica serovar Dublin (bovine-specific), Salmonella typhimurium (murine adapted, but zoonotic), and Salmonella enteritidis (poultry host-adapted) in 3-week-old calves. All Salmonella exposures increased cell surface CD14 and CD18 regardless of serovar. The greatest CD14 marker mean fluorescence was in monocytes and the greatest mean fluorescent of the marker mean was in neutrophils. Phagocytosis increased with all serovars, but was not different among them. Neutrophils had the greatest marker mean fluorescence for phagocytosis, with all serovars being equal. Oxidative burst increased in all serovars compared to control cells, but were not different among the serovars. Neutrophils and monocytes were similar in the oxidative burst, with limited oxidative burst detected in the primarily lymphocyte population. mRNA expression of TNF-α, IL-8, and IL-12, increased above the control cells whereas none of these serovars affected mRNA expression of TLR4. TNF-α was greatest in S. enterica and S. typhimurium, compared to Salmonella dublin. In contrast, IL-8 was expressed more in S. dublin than S. typhiurium, with S. Enteriditus intermediary. These results show while cell surface markers, phagocytosis, and oxidative burst were largely unaffected by serovar, cytokine and chemokine expression differed among the Salmonella serovars. It appears that internal responses of the cells differ, rather than cell recognition, creating pathogenicity differences among of the serovars, even in the neonate with developing immunity. PMID:25847354

  10. Development of a faradic impedimetric immunosensor for the detection of Salmonella typhimurium in milk.

    PubMed

    Mantzila, Aikaterini G; Maipa, Vassiliki; Prodromidis, Mamas I

    2008-02-15

    The development of a faradic impedimetric immunosensor for the detection of S. typhimurium in milk is described for first time. Polyclonal anti-Salmonella was cross-linked, in the presence of glutaraldehyde, on gold electrodes modified with a single 11-amino-1-undecanethiol (MUAM) self-assembled monolayer (SAM) or a mixed SAM of MUAM and 6-mercapto-1-hexanol at a constant 1 + 3 proportion, respectively. The mixed SAM was also deposited in the presence of triethylamine, which was used to prevent the formation of interplane hydrogen bonds among amine-terminated thiols. The effect of the different surface modifications on both the sensitivity and the selectivity of the immunosensors was investigated. The alteration of the interfacial features of the electrodes due to different modification or recognition steps, was measured by faradic electrochemical impedance spectroscopy in the presence of a hexacyanoferrate(II)/(III) redox couple. A substantial amplification of the measuring signal was achieved by performing the immunoreaction directly in culture samples. This resulted in immunosensors with great analytical features, as follows: (i) high sensitivity; the response of the immunosensors increases with respect to the detection time as a consequence of the simultaneous proliferation of the viable bacteria cells in the tested samples; (ii) validity; the response of the immunosensors is practically insensitive to the presence of dead cells; (iii) working simplicity; elimination of various centrifugation and washing steps, which are used for the isolation of bacteria cells from the culture. The proposed immunosensors were successfully used for the detection of S. typhimurium in experimentally inoculated milk samples. The effect of different postblocking agents on the performance of the immunosensors in real samples was also examined. PMID:18217725

  11. LeuO is a global regulator of gene expression in Salmonella enterica serovar Typhimurium.

    PubMed

    Dillon, Shane C; Espinosa, Elena; Hokamp, Karsten; Ussery, David W; Casadesús, Josep; Dorman, Charles J

    2012-09-01

    We report the first investigation of the binding of the Salmonella enterica LeuO LysR-type transcription regulator to its genomic targets in vivo. Chromatin-immunoprecipitation-on-chip identified 178 LeuO binding sites on the chromosome of S. enterica serovar Typhimurium strain SL1344. These sites were distributed across both the core and the horizontally acquired genome, and included housekeeping genes and genes known to contribute to virulence. Sixty-eight LeuO targets were co-bound by the global repressor protein, H-NS. Thus, while LeuO may function as an H-NS antagonist, these functions are unlikely to involve displacement of H-NS. RNA polymerase bound 173 of the 178 LeuO targets, consistent with LeuO being a transcription regulator. Thus, LeuO targets two classes of genes, those that are bound by H-NS and those that are not bound by H-NS. LeuO binding site analysis revealed a logo conforming to the TN(11) A motif common to LysR-type transcription factors. It differed in some details from a motif that we composed for Escherichia coli LeuO binding sites; 1263 and 1094 LeuO binding site locations were predicted in the S. Typhimurium SL1344 and E. coli MG1655 genomes respectively. Despite differences in motif composition, many LeuO target genes were common to both species. Thus, LeuO is likely to be a more important global regulator than previously suspected. PMID:22804842

  12. Nitrocompound activation by cell-free extracts of nitroreductase-proficient Salmonella typhimurium strains.

    PubMed

    Salamanca-Pinzón, S G; Camacho-Carranza, R; Hernández-Ojeda, S L; Espinosa-Aguirre, J J

    2006-11-01

    A characterization of nitrocompounds activation by cell-free extracts (CFE) of wild-type (AB(+)), SnrA deficient (B(+)), Cnr deficient (A(+)) and SnrA/Cnr deficient (AB(-)) Salmonella typhimurium strains has been done. The Ames mutagenicity test (S. typhimurium his(+) reversion assay) was used, as well as nitroreductase (NR) activity determinations where the decrease in absorbance generated by nitrofurantoin (NFN) reduction and NADP(H) oxidation in the presence of NFN, nitrofurazone (NFZ), metronidazole (MTZ) and 4-nitroquinoline-1-oxide (4NQO) were followed. Different aromatic and heterocyclic compounds were tested for mutagenic activation: 2-nitrofluorene (2-NF); 2,7-dinitrofluorene (2,7-DNF); 1-nitropyrene (1-NP), 1,3-dinitropyrene (1,3-DNP); 1,6-dinitropyrene (1,6-DNP); and 1,8-dinitropyrene (1,8-DNP). Differential mutagenicity was found with individual cell free extracts, being higher when the wild type or Cnr containing extract was used; nevertheless, depending on the nitrocompound, activation was found when either NR, SnrA or Cnr, were present. In addition, all nitrocompounds were more mutagenic after metabolic activation by CFE of NR proficient strains, although AB(-) extract still showed activation capacity. On the other hand, NR activity was predominantly catalyzed by wild type CFE followed by A(+), B(+) and AB(-) extracts in that order. We can conclude that results from the Ames test indicate that Cnr is the major NR, while NFN and NFZ reductions were predominantly catalyzed by SnrA. The characterization of the residual NR activity detected by the mutagenicity assay and the biochemical determinations in the AB(-) CFE needs further investigation. PMID:16998228

  13. Structure of the ribosomal interacting GTPase YjeQ from the enterobacterial species Salmonella typhimurium

    SciTech Connect

    Nichols, C. E.; Johnson, C.; Lamb, H. K.; Lockyer, M.; Charles, I. G.; Hawkins, A. R.; Stammers, D. K.

    2007-11-01

    The X-ray crystal structure of the GTPase YjeQ from S. typhimurium is presented and compared with those of orthologues from T. maritima and B. subtilis. The YjeQ class of P-loop GTPases assist in ribosome biogenesis and also bind to the 30S subunit of mature ribosomes. YjeQ ribosomal binding is GTP-dependent and thought to specifically direct protein synthesis, although the nature of the upstream signal causing this event in vivo is as yet unknown. The attenuating effect of YjeQ mutants on bacterial growth in Escherichia coli makes it a potential target for novel antimicrobial agents. In order to further explore the structure and function of YjeQ, the isolation, crystallization and structure determination of YjeQ from the enterobacterial species Salmonella typhimurium (StYjeQ) is reported. Whilst the overall StYjeQ fold is similar to those of the previously reported Thematoga maritima and Bacillus subtilis orthologues, particularly the GTPase domain, there are larger differences in the three OB folds. Although the zinc-finger secondary structure is conserved, significant sequence differences alter the nature of the external surface in each case and may reflect varying signalling pathways. Therefore, it may be easier to develop YjeQ-specific inhibitors that target the N- and C-terminal regions, disrupting the metabolic connectivity rather than the GTPase activity. The availability of coordinates for StYjeQ will provide a significantly improved basis for threading Gram-negative orthologue sequences and in silico compound-screening studies, with the potential for the development of species-selective drugs.

  14. Motility modulation by the small non-coding RNA SroC in Salmonella Typhimurium.

    PubMed

    Fuentes, Danitza N; Calderón, Paulina F; Acuña, Lillian G; Rodas, Paula I; Paredes-Sabja, Daniel; Fuentes, Juan A; Gil, Fernando; Calderón, Iván L

    2015-09-01

    Bacterial regulatory networks of gene expression include the interaction of diverse types of molecules such as the small non-coding RNAs (sRNAs) and their cognate messenger RNAs (mRNAs). In this study, we demonstrated that the Salmonella Typhimurium sRNA SroC is significantly expressed between the late-exponential and stationary phase of growth in an rpoS-dependent manner. The expression of flagellar genes predicted as targets of this sRNA was quantitatively analyzed in both a ΔsroC mutant and a SroC-overexpressing (pSroC) strain. Deletion of sroC increased flagellar gene expression (i.e. flhBAE and fliE). Conversely, overexpression of SroC reduced flhBAE and fliE expression. These observations correlated with phenotypic evaluation of motility, where sroC deletion slightly increased motility, which in turn, was drastically reduced upon overexpression of SroC. The effects of deletion and overexpression of sroC in biofilm formation were also examined, where the ΔsroC and pSroC strains exhibited a reduced and increased ability to form biofilm, respectively. Furthermore, electron microscopy revealed that the wild-type strain overexpressing SroC had a non-flagellated phenotype. Taken together, our results showed that S. Typhimurium sRNA SroC modulates the flagellar synthesis by down-regulating the expression of flhBAE and fliE genes. PMID:26293911

  15. Isolation of NAD cycle mutants defective in nicotinamide mononucleotide deamidase in Salmonella typhimurium.

    PubMed

    Cheng, W; Roth, J

    1995-12-01

    The NAD or pyridine nucleotide cycle is the sequence of reactions involved in the breakdown of NAD to nicotinamide mononucleotide (NMN) and regeneration of NAD. This cycle is fivefold more active during aerobic growth of Salmonella typhimurium and under this condition breaks down half of the NAD pool every 90 min. DNA ligase is known to convert NAD to NMN but is only a minor contributor to the NAD cycle during aerobic growth. The dominant aerobic route of NMN formation is otherwise uncharacterized. Accumulated NMN generated by either of these routes is potentially dangerous in that it can inhibit the essential enzyme DNA ligase. The reactions which recycle NMN to NAD may serve to minimize the inhibition of ligase and other enzymes by accumulated NMN. The predominant recycling reaction in S. typhimurium appears to be NMN deamidase, which converts NMN directly to the biosynthetic intermediate nicotinic acid mononucleotide. Mutants defective in this recycling step were isolated and characterized. By starting with a ligase-deficient (lig mutant) parent strain that requires deamidase to assimilate exogenous NMN, two classes of mutants that are unable to grow on minimal NMN media were isolated. One class (pncC) maps at 83.7 min and shows only 2% of the wild-type levels of NMN deamidase. Under aerobic conditions, a lig+ allele allows a pncC mutant to grow on NMN and restores some deamidase activity. This growth ability and enzyme activity are not found in lig+ strains grown without oxygen. This suggests that the existence of a second NMN deamidase (pncL) dependent on ligase and stimulated during aerobic growth. The second class of mutants (pncD) gains a requirement for isoleucine plus valine with growth in the presence of exogenous NMN. We propose that pncD mutations reduce the activity of an ilv biosynthetic enzyme that is naturally sensitive to inhibition by NMN. PMID:7592458

  16. Sub-Inhibitory Fosmidomycin Exposures Elicits Oxidative Stress in Salmonella enterica Serovar typhimurium LT2

    PubMed Central

    Fox, David T.; Schmidt, Emily N.; Tian, Hongzhao; Dhungana, Suraj; Valentine, Michael C.; Warrington, Nicole V.; Phillips, Paul D.; Finney, Kellan B.; Cope, Emily K.; Leid, Jeff G.; Testa, Charles A.; Koppisch, Andrew T.

    2014-01-01

    Fosmidomycin is a time-dependent nanomolar inhibitor of methylerythritol phosphate (MEP) synthase, which is the enzyme that catalyzes the first committed step in the MEP pathway to isoprenoids. Importantly, fosmidomycin is one of only a few MEP pathway-specific inhibitors that exhibits antimicrobial activity. Most inhibitors identified to date only exhibit activity against isolated pathway enzymes. The MEP pathway is the sole route to isoprenoids in many bacteria, yet has no human homologs. The development of inhibitors of this pathway holds promise as novel antimicrobial agents. Similarly, analyses of the bacterial response toward MEP pathway inhibitors provides valuable information toward the understanding of how emergent resistance may ultimately develop to this class of antibiotics. We have examined the transcriptional response of Salmonella enterica serovar typhimurium LT2 to sub-inhibitory concentrations of fosmidomycin via cDNA microarray and RT-PCR. Within the regulated genes identified by microarray were a number of genes encoding enzymes associated with the mediation of reactive oxygen species (ROS). Regulation of a panel of genes implicated in the response of cells to oxidative stress (including genes for catalases, superoxide dismutases, and alkylhydrogen peroxide reductases) was investigated and mild upregulation in some members was observed as a function of fosmidomycin exposure over time. The extent of regulation of these genes was similar to that observed for comparable exposures to kanamycin, but differed significantly from tetracycline. Furthermore, S. typhimurium exposed to sub-inhibitory concentrations of fosmidomycin displayed an increased sensitivity to exogenous H2O2 relative to either untreated controls or kanamycin-treated cells. Our results suggest that endogenous oxidative stress is one consequence of exposures to fosmidomycin, likely through the temporal depletion of intracellular isoprenoids themselves, rather than other mechanisms that

  17. A role for Salmonella typhimurium cbiK in cobalamin (vitamin B12) and siroheme biosynthesis.

    PubMed Central

    Raux, E; Thermes, C; Heathcote, P; Rambach, A; Warren, M J

    1997-01-01

    The role of cbiK, a gene found encoded within the Salmonella typhimurium cob operon, has been investigated by studying its in vivo function in Escherichia coli. First, it was found that cbiK is not required for cobalamin biosynthesis in the presence of a genomic cysG gene (encoding siroheme synthase) background. Second, in the absence of a genomic cysG gene, cobalamin biosynthesis in E. coli was found to be dependent upon the presence of cobA(P. denitrificans) (encoding the uroporphyrinogen III methyltransferase from Pseudomonas denitrificans) and cbiK. Third, complementation of the cysteine auxotrophy of the E. coli cysG deletion strain 302delta a could be attained by the combined presence of cobA(P. denitrificans) and the S. typhimurium cbiK gene. Collectively these results suggest that CbiK can function in fashion analogous to that of the N-terminal domain of CysG (CysG(B)), which catalyzes the final two steps in siroheme synthesis, i.e., NAD-dependent dehydrogenation of precorrin-2 to sirohydrochlorin and ferrochelation. Thus, phenotypically CysG(B) and CbiK have very similar properties in vivo, although the two proteins do not have any sequence similarity. In comparison to CysG, CbiK appears to have a greater affinity for Co2+ than for Fe2+, and it is likely that cbiK encodes an enzyme whose primary role is that of a cobalt chelatase in corrin biosynthesis. PMID:9150215

  18. Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum

    PubMed Central

    Riquelme, Sebastián; Varas, Macarena; Valenzuela, Camila; Velozo, Paula; Chahin, Nicolás; Aguilera, Paulina; Sabag, Andrea; Labra, Bayron; Álvarez, Sergio A.; Chávez, Francisco P.; Santiviago, Carlos A.

    2016-01-01

    The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process. To do this, we performed infection assays using axenic cultures of D. discoideum co-cultured with wild-type S. Typhimurium and/or defined mutant strains. Our results confirmed that wild-type S. Typhimurium is able to survive intracellularly in D. discoideum. In contrast, mutants ΔaroA and ΔwaaL are defective in intracellular survival in this amoeba. Next, we included in our study a group of mutants in genes directly linked to Salmonella virulence. Of note, mutants ΔinvA, ΔssaD, ΔclpV, and ΔphoPQ also showed an impaired ability to survive intracellularly in D. discoideum. This indicates that S. Typhimurium requires a functional biosynthetic pathway of aromatic compounds, a lipopolysaccharide containing a complete O-antigen, the type III secretion systems (T3SS) encoded in SPI-1 and SPI-2, the type VI secretion system (T6SS) encoded in SPI-6 and PhoP/PhoQ two-component system to survive in D. discoideum. To our knowledge, this is the first report on the requirement of O-antigen and T6SS in the survival of Salmonella within amoebae. In addition, mutants ΔinvA and ΔssaD were internalized in higher numbers than the wild-type strain during competitive infections, suggesting that S. Typhimurium requires the T3SS encoded in SPI-1 and SPI-2 to evade phagocytosis by D. discoideum. Altogether, these results indicate that S. Typhimurium exploits a common set of genes and molecular mechanisms to survive within amoeba and animal host cells. The use of D. discoideum as a model for host–pathogen interactions will allow us to discover the gene repertoire used by Salmonella to survive inside the amoeba and to study the cellular processes that are affected

  19. Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum.

    PubMed

    Riquelme, Sebastián; Varas, Macarena; Valenzuela, Camila; Velozo, Paula; Chahin, Nicolás; Aguilera, Paulina; Sabag, Andrea; Labra, Bayron; Álvarez, Sergio A; Chávez, Francisco P; Santiviago, Carlos A

    2016-01-01

    The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process. To do this, we performed infection assays using axenic cultures of D. discoideum co-cultured with wild-type S. Typhimurium and/or defined mutant strains. Our results confirmed that wild-type S. Typhimurium is able to survive intracellularly in D. discoideum. In contrast, mutants ΔaroA and ΔwaaL are defective in intracellular survival in this amoeba. Next, we included in our study a group of mutants in genes directly linked to Salmonella virulence. Of note, mutants ΔinvA, ΔssaD, ΔclpV, and ΔphoPQ also showed an impaired ability to survive intracellularly in D. discoideum. This indicates that S. Typhimurium requires a functional biosynthetic pathway of aromatic compounds, a lipopolysaccharide containing a complete O-antigen, the type III secretion systems (T3SS) encoded in SPI-1 and SPI-2, the type VI secretion system (T6SS) encoded in SPI-6 and PhoP/PhoQ two-component system to survive in D. discoideum. To our knowledge, this is the first report on the requirement of O-antigen and T6SS in the survival of Salmonella within amoebae. In addition, mutants ΔinvA and ΔssaD were internalized in higher numbers than the wild-type strain during competitive infections, suggesting that S. Typhimurium requires the T3SS encoded in SPI-1 and SPI-2 to evade phagocytosis by D. discoideum. Altogether, these results indicate that S. Typhimurium exploits a common set of genes and molecular mechanisms to survive within amoeba and animal host cells. The use of D. discoideum as a model for host-pathogen interactions will allow us to discover the gene repertoire used by Salmonella to survive inside the amoeba and to study the cellular processes that are affected

  20. 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

  1. Regulation of expression of the ilvB operon in Salmonella typhimurium.

    PubMed

    Weinberg, R A; Burns, R O

    1984-12-01

    The ilvB gene of Salmonella typhimurium encodes the valine-sensitive form of acetohydroxy acid synthase, acetohydroxy acid synthase I, which catalyzes the first step in the parallel biosynthesis of isoleucine and valine. Although nearly all of the other genes involved in this pathway are clustered at minute 83, ilvB was found to lie at minute 80.5. Expression of ilvB was shown to be nearly completely repressed by the end products leucine and valine. Studies in which we used strains with mutations in cya (adenylate cyclase) and crp (cAMP receptor protein) demonstrated that synthesis of acetohydroxy acid synthase I is enhanced by the cAMP-cAMP receptor protein complex. Although no stimulation was achieved by growth on poor carbon sources, introduction of crp on a multicopy plasmid led to markedly increased expression. Strains of S. typhimurium lacking valine-resistant acetohydroxy acid synthase II (ilvG) are like Escherichia coli K-12 in that they are not able to grow in the presence of L-valine owing to a conditional isoleucine auxotrophy. The valine toxicity of these ilvG mutants of S. typhimurium was overcome by increasing the level of acetohydroxy acid synthase I. Enzyme activity could be elevated either by maximally derepressing expression with severe leucine limitation, by introduction of either ilvB or crp on a multicopy plasmid, or by the presence of the ilv-513 mutation. This mutation, which is closely linked to genes encoding the phosphoenol pyruvate:sugar phosphotransferase system (pts), causes highly elevated expression of ilvB that is refractory to repression by leucine and valine, as is the major ilv operon. The response of ilvB to the cAMP-cAMP receptor protein complex was not affected by this lesion. Data obtained by using this mutant led us to propose that the two modes of regulation act independently. We also present some evidence which suggests that ilvB expression may be affected by the phosphoenol pyruvate:sugar phosphotransferase system. PMID

  2. Salmonella enterica Serovar Typhimurium and Escherichia coli Contamination of Root and Leaf Vegetables Grown in Soils with Incorporated Bovine Manure

    PubMed Central

    Natvig, Erin E.; Ingham, Steven C.; Ingham, Barbara H.; Cooperband, Leslie R.; Roper, Teryl R.

    2002-01-01

    Bovine manure, with or without added Salmonella enterica serovar Typhimurium (three strains), was incorporated into silty clay loam (SCL) and loamy sand (LS) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers. The S. enterica serovar Typhimurium inoculum was 4 to 5 log CFU/g in manure-fertilized soil. The conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily average Madison, Wis., weather conditions (hourly temperatures, rainfall, daylight, and humidity) for a 1 March or a 1 June manure application and subsequent vegetable growing seasons ending 9 August or 28 September, respectively. Core soil samples were taken biweekly from both inoculated and uninoculated soil beds in each chamber. Radishes, arugula, and carrots were planted in soil beds, thinned, and harvested. Soils, thinned vegetables, and harvested vegetables were analyzed for S. enterica serovar Typhimurium and Escherichia coli (indigenous in manure). After the 1 March manure application, S. enterica serovar Typhimurium was detected at low levels in both soils on 31 May, but not on vegetables planted 1 May and harvested 12 July from either soil. After the 1 June manure application, S. enterica serovar Typhimurium was detected in SCL soil on 7 September and on radishes and arugula planted in SCL soil on 15 August and harvested on 27 September. In LS soil, S. enterica serovar Typhimurium died at a similar rate (P ≥ 0.05) after the 1 June manure application and was less often detected on arugula and radishes harvested from this soil compared to the SCL soil. Pathogen levels on vegetables were decreased by washing. Manure application in cool (daily average maximum temperature of <10°C) spring conditions is recommended to ensure that harvested vegetables are not contaminated with S. enterica serovar Typhimurium. Manure application under warmer (daily average maximum

  3. Differences in Host Cell Invasion and Salmonella Pathogenicity Island 1 Expression between Salmonella enterica Serovar Paratyphi A and Nontyphoidal S. Typhimurium.

    PubMed

    Elhadad, Dana; Desai, Prerak; Grassl, Guntram A; McClelland, Michael; Rahav, Galia; Gal-Mor, Ohad

    2016-04-01

    Active invasion into nonphagocytic host cells is central to Salmonella enterica pathogenicity and dependent on multiple genes within Salmonella pathogenicity island 1 (SPI-1). Here, we explored the invasion phenotype and the expression of SPI-1 in the typhoidal serovarS Paratyphi A compared to that of the nontyphoidal serovarS Typhimurium. We demonstrate that while S. Typhimurium is equally invasive under both aerobic and microaerobic conditions, S. Paratyphi A invades only following growth under microaerobic conditions. Transcriptome sequencing (RNA-Seq), reverse transcription-PCR (RT-PCR), Western blot, and secretome analyses established that S. Paratyphi A expresses much lower levels of SPI-1 genes and secretes lesser amounts of SPI-1 effector proteins than S. Typhimurium, especially under aerobic growth. Bypassing the native SPI-1 regulation by inducible expression of the SPI-1 activator, HilA, considerably elevated SPI-1 gene expression, host cell invasion, disruption of epithelial integrity, and induction of proinflammatory cytokine secretion by S. Paratyphi A but not by S. Typhimurium, suggesting that SPI-1 expression is naturally downregulated inS Paratyphi A. Using streptomycin-treated mice, we were able to establish substantial intestinal colonization byS Paratyphi A and showed moderately higher pathology and intestinal inflammation in mice infected with S. Paratyphi A overexpressing hilA Collectively, our results reveal unexpected differences in SPI-1 expression between S. Paratyphi A andS Typhimurium, indicate that S. Paratyphi A host cell invasion is suppressed under aerobic conditions, and suggest that lower invasion in aerobic sites and suppressed expression of immunogenic SPI-1 components contributes to the restrained inflammatory infection elicited by S. Paratyphi A. PMID:26857569

  4. Characterization and differential gene expression between two phenotypic phase variants in Salmonella enterica serovar Typhimurium.

    PubMed

    Patterson, Sheila K; Borewicz, Klaudyna; Johnson, Timothy; Xu, Wayne; Isaacson, Richard E

    2012-01-01

    Salmonella enterica serovar Typhimurium strain 798 has previously been shown to undergo phenotypic phase variation. One of the phenotypes expresses virulence traits such as adhesion, while the other phenotype does not. Phenotypic phase variation appears to correlate with the ability of this strain to cause persistent, asymptomatic infections of swine. A new method to detect cells in either phenotypic phase was developed using Evans Blue-Uranine agar plates. Using this new assay, rates of phenotypic phase variation were obtained. The rate of phase variation from non-adhesive to adhesive phenotype was approximately 10(-4) per cell per generation while phase variation from the adhesive to the non-adhesive phenotype was approximately 10(-6) per cell per generation. Two highly virulent S. Typhimurium strains, SL1344 and ATCC 14028, were also shown to undergo phase variation. However, while the rate from adhesive to non-adhesive phenotype was approximately the same as for strain 798, the non-adhesive to adhesive phenotype shift was 37-fold higher. Differential gene expression was measured using RNA-Seq. Eighty-three genes were more highly expressed by 798 cells in the adhesive phenotype compared to the non-adhesive cells. Most of the up-regulated genes were in virulence genes and in particular all genes in the Salmonella pathogenicity island 1 were up-regulated. When compared to the virulent strain SL1344, expression of the virulence genes was approximately equal to those up-regulated in the adhesive phenotype of strain 798. A comparison of invasive ability demonstrated that strain SL1344 was the most invasive followed by the adhesive phenotype of strain 798, then the non-adhesive phenotype of strain 798. The least invasive strain was ATCC 14028. The genome of strain 798 was sequenced and compared to SL1344. Both strains had very similar genome sequences and gene deletions could not readily explain differences in the rates of phase variation from non-adhesive to the

  5. Effect of ionizing radiation dose, temperature, and atmosphere on the survival of Salmonella typhimurium in sterile, mechanically deboned chicken meat

    SciTech Connect

    Thayer, D.W.; Boyd, G. )

    1991-02-01

    The response to gamma radiation (0 to 3.60 kGy; 100 krad = 1 kGy) of Salmonella typhimurium was tested in otherwise sterile, mechanically deboned chicken meat (MDCM) in the absence of competing microflora. Response was determined at temperatures of -20 to +20 C and when the MDCM was packaged in vacuum or in the presence of air. A central composite response-surface design was used to test the response of the pathogen to the treatments in a single experiment. Predictive equations were developed from the analyses of variances of the resulting data. The accuracy of each predictive equation was tested by further studies of the effects of gamma radiation on S. typhimurium in the presence or absence of air at -20, 0, and +20 C. All data were then analyzed to refine the predictive equations further. Both the original and the refined equations adequately predicted the response of S. typhimurium in MDCM to gamma radiation doses up to 3.60 kGy in the presence of air or in vacuo. Gamma irradiation was significantly more lethal for S. typhimurium in the presence of air and at higher temperatures. The final equations predict a reduction in the number of surviving Salmonella in MDCM irradiated to 1.50 kGy at -20 C of 2.53 logs in air or 2.12 logs if irradiated in vacuum. If the contaminated MDCM were to receive a dose of 3.0 kGy at -20 C in air, the number of Salmonella would be decreased by 4.78 logs, and if irradiated in vacuum, by 4.29 logs.

  6. Live and inactivated Salmonella enterica serovar Typhimurium stimulate similar but distinct transcriptome profiles in bovine macrophages and dendritic cells.

    PubMed

    Jensen, Kirsty; Gallagher, Iain J; Kaliszewska, Anna; Zhang, Chen; Abejide, Oluyinka; Gallagher, Maurice P; Werling, Dirk; Glass, Elizabeth J

    2016-01-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is a major cause of gastroenteritis in cattle and humans. Dendritic cells (DC) and macrophages (Mø) are major players in early immunity to Salmonella, and their response could influence the course of infection. Therefore, the global transcriptional response of bovine monocyte-derived DC and Mø to stimulation with live and inactivated S. Typhimurium was compared. Both cell types mount a major response 2 h post infection, with a core common response conserved across cell-type and stimuli. However, three of the most affected pathways; inflammatory response, regulation of transcription and regulation of programmed cell death, exhibited cell-type and stimuli-specific differences. The expression of a subset of genes associated with these pathways was investigated further. The inflammatory response was greater in Mø than DC, in the number of genes and the enhanced expression of common genes, e.g., interleukin (IL) 1B and IL6, while the opposite pattern was observed with interferon gamma. Furthermore, a large proportion of the investigated genes exhibited stimuli-specific differential expression, e.g., Mediterranean fever. Two-thirds of the investigated transcription factors were significantly differentially expressed in response to live and inactivated Salmonella. Therefore the transcriptional responses of bovine DC and Mø during early S. Typhimurium infection are similar but distinct, potentially due to the overall function of these cell-types. The differences in response of the host cell will influence down-stream events, thus impacting on the subsequent immune response generated during the course of the infection. PMID:27000047

  7. Molecular Profiling: Catecholamine Modulation of Gene Expression in Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium.

    PubMed

    Bearson, Bradley L

    2016-01-01

    Investigations of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium have demonstrated that these bacterial pathogens can respond to the presence of catecholamines including norepinephrine and/or epinephrine in their environment by modulating gene expression and exhibiting various phenotypes. For example, one of the most intensively investigated phenotypes following exposure of E. coli and S. Typhimurium to norepinephrine is enhanced bacterial growth in a serum-based medium. Host-pathogen investigations have demonstrated that the mammalian host utilizes nutritional immunity to sequester iron and prevent extraintestinal growth by bacterial pathogens. However, Salmonella and certain E. coli strains have a genetic arsenal designed for subversion and subterfuge of the host. Norepinephrine enhances bacterial growth due, in part, to increased iron availability, and transcriptional profiling indicates differential expression of genes encoding iron acquisition and transport proteins. Bacterial motility of E. coli and S. Typhimurium is also enhanced in the presence of catecholamines and increased flagellar gene expression has been described. Furthermore, epinephrine and norepinephrine are chemoattractants for E. coli O157:H7. In S. Typhimurium, norepinephrine enhances horizontal gene transfer and increases expression of genes involved in plasmid transfer. Exposure of E. coli O157:H7 to norepinephrine increases expression of the genes encoding Shiga toxin and operons within the locus of enterocyte effacement (LEE). Alterations in the transcriptional response of enteric bacteria to catecholamine exposure in vivo are predicted to enhance bacterial colonization and pathogen virulence. This chapter will review the current literature on the transcriptional response of E. coli and S. Typhimurium to catecholamines. PMID:26589218

  8. Granulocytes Impose a Tight Bottleneck upon the Gut Luminal Pathogen Population during Salmonella Typhimurium Colitis

    PubMed Central

    Maier, Lisa; Diard, Médéric; Sellin, Mikael E.; Chouffane, Elsa-Sarah; Trautwein-Weidner, Kerstin; Periaswamy, Balamurugan; Slack, Emma; Dolowschiak, Tamas; Stecher, Bärbel; Loverdo, Claude; Regoes, Roland R.; Hardt, Wolf-Dietrich

    2014-01-01

    Topological, chemical and immunological barriers are thought to limit infection by enteropathogenic bacteria. However, in many cases these barriers and their consequences for the infection process remain incompletely understood. Here, we employed a mouse model for Salmonella colitis and a mixed inoculum approach to identify barriers limiting the gut luminal pathogen population. Mice were infected via the oral route with wild type S. Typhimurium (S. Tm) and/or mixtures of phenotypically identical but differentially tagged S. Tm strains (“WITS”, wild-type isogenic tagged strains), which can be individually tracked by quantitative real-time PCR. WITS dilution experiments identified a substantial loss in tag/genetic diversity within the gut luminal S. Tm population by days 2–4 post infection. The diversity-loss was not attributable to overgrowth by S. Tm mutants, but required inflammation, Gr-1+ cells (mainly neutrophilic granulocytes) and most likely NADPH-oxidase-mediated defense, but not iNOS. Mathematical modelling indicated that inflammation inflicts a bottleneck transiently restricting the gut luminal S. Tm population to approximately 6000 cells and plating experiments verified a transient, inflammation- and Gr-1+ cell-dependent dip in the gut luminal S. Tm population at day 2 post infection. We conclude that granulocytes, an important clinical hallmark of S. Tm-induced inflammation, impose a drastic bottleneck upon the pathogen population. This extends the current view of inflammation-fuelled gut-luminal Salmonella growth by establishing the host response in the intestinal lumen as a double-edged sword, fostering and diminishing colonization in a dynamic equilibrium. Our work identifies a potent immune defense against gut infection and reveals a potential Achilles' heel of the infection process which might be targeted for therapy. PMID:25522364

  9. Negative regulatory loci coupling flagellin synthesis to flagellar assembly in Salmonella typhimurium.

    PubMed Central

    Gillen, K L; Hughes, K T

    1991-01-01

    The complex regulation of flagellin gene expression in Salmonella typhimurium was characterized in vivo by using lac transcriptional fusions to the two flagellin structural genes (fliC [H1] and fljB [H2]). Phase variation was measured as the rate of switching of flagellin gene expression. Switching frequencies varied from 1/500 per cell per generation to 1/10,000 per cell per generation depending on the particular insertion and the direction of switching. There is a 4- to 20-fold bias in favor of switching from the fljB(On) to the fljB(Off) orientation. Random Tn10dTc insertions were isolated which failed to express flagellin. While most of these insertions mapped to loci known to be required for flagellin expression, several new loci were identified. The presence of functional copies of all of the genes responsible for complete flagellar assembly, except the hook-associated proteins (flgK, flgL, and fliD gene products), were required for expression of the fliC or fljB flagellin genes. Two novel loci involved in negative regulation of fliC and fljB in fla mutant backgrounds were identified. One of these loci, designated the flgR locus, mapped to the flg operon at 23 min on the Salmonella linkage map. An flgR insertion mutation resulted in relief of repression of the fliC and fljB genes in all fla mutant backgrounds except for mutants in the positive regulatory loci (flhC, flhD, and fliA genes). PMID:1848842

  10. Regulated delayed synthesis of lipopolysaccharide and enterobacterial common antigen of Salmonella Typhimurium enhances immunogenicity and cross-protective efficacy against heterologous Salmonella challenge.

    PubMed

    Huang, Chun; Liu, Qing; Luo, Yali; Li, Pei; Liu, Qiong; Kong, Qingke

    2016-08-01

    Lipopolysaccharide (LPS) O-antigen and enterobacterial common antigen (ECA) are two major polysaccharide structures on the surface of Salmonella enterica serovar Typhimurium. Previous studies have demonstrated that regulated truncation of LPS enhances the cross-reaction against conserved outer membrane proteins (OMPs) from enteric bacteria. We speculate that the regulation of both O-antigen and ECA may enhance the induction of immune responses against conserved OMPs from enteric bacteria. In this work we targeted rfbB and rffG genes which encode dTDP-glucose 4,6-dehydratases and share the same function in regulating O-antigen and ECA synthesis. We constructed a mutant, S496 (ΔrfbB6 ΔrffG7 ΔpagL73::TT araC PBADrfbB-3), in which rfbB gene expression was dependent on exogenously supplied arabinose during in vitro growth and achieved the simultaneous tight regulation of both LPS and ECA synthesis, as demonstrated by the LPS profile and Western blotting using antisera against LPS and ECA. When administered orally, S. Typhimurium S496 was completely attenuated for virulence but still retained the capacity to colonize and disseminate in mice. In addition, we found that oral immunization with S496 resulted in increased immune responses against OMPs from enteric bacteria and enhanced survival compared with immunization with S492 possessing ΔrfbB6 ΔrffG8 mutations when challenged with lethal doses of Salmonella Choleraesuis or Salmonella Enteritidis. These results indicate that S. Typhimurium arabinose-regulated rfbB strain S496 is a good vaccine candidate, conferring cross-protection against lethal challenge with heterologous Salmonella. PMID:27423383

  11. Isolation of a hybrid F' factor-carrying Escherichia coli lactose region and Salmonella typhimurium histidine region, F42-400 (F' ts114 lac+, his+): its partial characterization and behavior in Salmonella typhimurium.

    PubMed Central

    Rao, R N; Pereira, M G

    1975-01-01

    Episome F' ts114 lac+ (F42-114) was transferred into Salmonella typhimurium carrying an F'his+ (FS400) episome, and fused episome F' ts114 lac+, his+ (F42-400) was obtained. Episome F42-400 could be transferred to S. typhimurium, Escherichia coli and Klebsiella pneumoniae. Identification of the episome was based on: (i) temperature sensitivity of the Lac+ and His+ phenotypes; (ii) the fact that F- segregants, obtained after temperature curing or acridine orange curing, were simultaneously Lac- and His-; and (iii) linkage of lac+ with his+ in episomal transfers to E. coli and S. typhimurium. The frequency of episome transfer was influenced by the genotype of the donor. Plasmid LT2, prevalent in S. typhimurium LT2 strains, was suggested to be responsible for the low fertility of S. typhimurium donors. Episome F42-400 was capable of chromosome mobilization, and the extent of chromosome mobilization was not influenced by the presence or absence of the histidine region on the donor chromosome. Growth in a defined medium with acridine orange was able to cure F42-400. The frequency of curing was increased (the frequency of His+ cells was 0.0001%) if the cells were grown at 40 C in the presence of acridine orange. Selection for temperature-resistant Lac+, His+ derivatives in a strain without histidine deletion yielded Hfr strains. However, similar and stronger selections in strains without the chromosomal histidine region failed to yield Hfr strains. Our inability to obtain Hfr's in strains without the chromosomal histidine region was explained by assuming that the episome F42-400 has lost the F sites involved in integration into the S. typhimurium chromosome. PMID:1099076

  12. Expression of Antimicrobial Peptides in Cecal Tonsils of Chickens Treated with Probiotics and Infected with Salmonella enterica Serovar Typhimurium

    PubMed Central

    Akbari, Mohammad Reza; Haghighi, Hamid Reza; Chambers, James R.; Brisbin, Jennifer; Read, Leah R.; Sharif, Shayan

    2008-01-01

    Several strategies currently exist for control of Salmonella enterica serovar Typhimurium colonization in the chicken intestine, among which the use of probiotics is of note. Little is known about the underlying mechanisms of probiotic-mediated reduction of Salmonella colonization. In this study, we asked whether the effect of probiotics is mediated by antimicrobial peptides, including avian beta-defensins (also called gallinacins) and cathelicidins. Four treatment groups were included in this study: a negative-control group, a probiotic-treated group, a Salmonella-infected group, and a probiotic-treated and Salmonella-infected group. On days 1, 3, and 5 postinfection (p.i.), the cecal tonsils were removed, and RNA was extracted and used for measurement of avian beta-defensin 1 (AvBD1), AvBD2, AvBD4, AvBD6, and cathelicidin gene expression by real-time PCR. The expressions of all avian beta-defensins and cathelicidin were detectable in all groups, irrespective of treatment and time point. Probiotic treatment and Salmonella infection did not affect the expression of any of the investigated genes on day 1 p.i. Furthermore, probiotic treatment had no significant effect on the expression of the genes at either 3 or 5 days p.i. However, the expression levels of all five genes were significantly increased (P < 0.05) in response to Salmonella infection at 3 and 5 days p.i. However, administration of probiotics eliminated the effect of Salmonella infection on the expression of antimicrobial genes. These findings indicate that the expression of antimicrobial peptides may be repressed by probiotics in combination with Salmonella infection or, alternatively, point to the possibility that, due to a reduction in Salmonella load in the intestine, these genes may not be induced. PMID:18827189

  13. Neutrophils mediate Salmonella Typhimurium clearance through the GBP4 inflammasome-dependent production of prostaglandins

    PubMed Central

    Tyrkalska, Sylwia D.; Candel, Sergio; Angosto, Diego; Gómez-Abellán, Victoria; Martín-Sánchez, Fátima; García-Moreno, Diana; Zapata-Pérez, Rubén; Sánchez-Ferrer, Álvaro; Sepulcre, María P.; Pelegrín, Pablo; Mulero, Victoriano

    2016-01-01

    Inflammasomes are cytosolic molecular platforms that alert the immune system about the presence of infection. Here we report that zebrafish guanylate-binding protein 4 (Gbp4), an IFNγ-inducible GTPase protein harbouring a C-terminal CARD domain, is required for the inflammasome-dependent clearance of Salmonella Typhimurium (ST) by neutrophils in vivo. Despite the presence of the CARD domain, Gbp4 requires the universal inflammasome adaptor Asc for mediating its antibacterial function. In addition, the GTPase activity of Gbp4 is indispensable for inflammasome activation and ST clearance. Mechanistically, neutrophils are recruited to the infection site through the inflammasome-independent production of the chemokine (CXC motif) ligand 8 and leukotriene B4, and then mediate bacterial clearance through the Gbp4 inflammasome-dependent biosynthesis of prostaglandin D2. Our results point to GBPs as key inflammasome adaptors required for prostaglandin biosynthesis and bacterial clearance by neutrophils and suggest that transient activation of the inflammasome may be used to treat bacterial infections. PMID:27363812

  14. Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay

    PubMed Central

    Liu, Li; Chen, Ling; Floehr, Tilman; Xiao, Hongxia; Bluhm, Kerstin; Hollert, Henner; Wu, Lingling

    2015-01-01

    Sediments in estuaries are of important environmental concern because they may act as pollution sinks and sources to the overlying water body. These sediments can be accumulated by benthic organisms. This study assessed the mutagenic potential of sediment extracts from the Yangtze River estuary by using the Ames fluctuation assay with the Salmonella typhimurium his (−) strain TA98 (frameshift mutagen indicator) and TA100 (baseshift mutagen indicator). Most of the sediment samples were mutagenic to the strain TA98, regardless of the presence or absence of exogenous metabolic activation (S9 induction by β-naphthoflavone/phenobarbital). However, none of the samples were mutagenic to the strain TA100. Thus, the mutagenicity pattern was mainly frameshift mutation, and the responsible toxicants were both direct (without S9 mix) and indirect (with S9 mix) mutagens. The mutagenicity of the sediment extracts increased when S9 was added. Chemical analysis showed a poor correlation between the content of priority polycyclic aromatic hydrocarbons and the detected mutagenicity in each sample. The concept of effect-directed analysis was used to analyze possible compounds responsible for the detected mutagenic effects. With regard to the mutagenicity of sediment fractions, non-polar compounds as well as weakly and moderately polar compounds played a main role. Further investigations should be conducted to identify the responsible components. PMID:26606056

  15. Binding of Salmonella typhimurium lipopolysaccharides to rat high-density lipoproteins.

    PubMed Central

    Munford, R S; Hall, C L; Dietschy, J M

    1981-01-01

    These studies were undertaken to investigate the binding of gram-negative bacterial lipopolysaccharides (LPS) to high-density lipoproteins (HDL) of rat plasma. Purified Salmonella typhimurium LPS, intrinsically labeled with [3H]-galactose, bound rapidly in vitro to isolated rat HDL. Maximal binding of LPS to HDL occurred when LPS and HDL were incubated with lipoprotein-free plasma (rho greater than 1.21 g/ml). Since LPS, when purified, form large aggregates, we tested the hypothesis that disaggregation of LPS enhances LPS-HDL binding. We found that calcium chloride (1 mM), an agent which prevents LPS disaggregation, inhibited binding of LPS to HDL by interfering with the modification of LPS by lipoprotein-free plasma. Conversely, sodium deoxycholate (0.15 g/dl), which disaggregates LPS, greatly increased binding of LPS to HDL in the absence of lipoprotein-free plasma. Analysis of labeled LPS by sodium deodecyl sulfate-polyacrylamide gel electrophoresis showed only minor differences in the sizes of LPS molecules before and after binding to HDL, suggesting that chemical modification of LPS is not required for binding. The results provide evidence that disaggregation increases the binding of LPS to HDL. PMID:7037642

  16. Salmonella typhimurium proP gene encodes a transport system for the osmoprotectant betaine.

    PubMed

    Cairney, J; Booth, I R; Higgins, C F

    1985-12-01

    Betaine (N,N,N-trimethylglycine) can be accumulated to high intracellular concentrations and serves an important osmoprotective function in enteric bacteria. We found that the proP gene of Salmonella typhimurium, originally identified as encoding a minor transport system for proline (permease PP-II), plays an important role in betaine uptake. Mutations in proP reduced the ability of betaine to serve as an osmoprotectant. Transport of betaine into the cells was also severely impaired in these mutants. The kinetics of uptake via PP-II suggest that betaine, rather than proline, is the important physiological substrate for this transport system. Betaine uptake via PP-II was regulated by osmotic pressure at two different levels: transcription of the proP gene was increased by increasing osmolarity, and, in addition, activity of the transport system itself was dependent upon the osmotic pressure of the medium. The specificity of the transport system was also altered by increasing osmolarity which enhanced the affinity for betaine while reducing that for proline. PMID:3905767

  17. DNA supercoiling and the leu-500 promoter mutation of Salmonella typhimurium.

    PubMed Central

    Richardson, S M; Higgins, C F; Lilley, D M

    1988-01-01

    DNA supercoiling is an important, but relatively poorly understood factor which influences promoter function. leu-500 is a point mutation in the promoter of the leucine operon of Salmonella typhimurium which confers leucine auxotrophy. It can be phenotypically suppressed by mutations in the topA gene, which encodes topoisomerase I, implicating DNA supercoiling in the regulation of this promoter. We have demonstrated that phenotypic suppression of this mutant promoter is transcriptional, and that topA mutations restore function to the mutant promoter. Transcription from the leu-500 promoter was examined in a series of strains harbouring topA and tos (presumptive gyr) mutations, each of which exhibits a different level of in vivo plasmid supercoiling. Promoter function did not correlate with the level of supercoiling but rather with the presence or absence of a functional topA gene. Furthermore, when cloned onto a multicopy plasmid, the leu-500 promoter failed to function, even in a topA background. Thus, local rather than global changes in DNA topology are implicated in the activation of this promoter. Images PMID:2844526

  18. A Salmonella Typhimurium 197 outbreak linked to the consumption of lambs' liver in Sydney, NSW

    PubMed Central

    HESS, I. M. R.; NEVILLE, L. M.; McCARTHY, R.; SHADBOLT, C. T.; McANULTY, J. M.

    2008-01-01

    SUMMARY We identified an increase in the number of cases of Salmonella Typhimurium phage type 197 in New South Wales in February 2005. Cases were predominantly of Lebanese descent. To identify risk factors for illness, we conducted an unmatched case-control study including 12 cases and 21 controls. Eight of 12 cases (67%) and no controls reported eating lambs' liver (OR incalculable, P<0·05), and seven of nine cases (78%) and one of 21 controls (5%) reported eating fresh fish (OR 70·0, P<0·05). Among participants who did not eat liver, there was a strong association between eating fish and illness (OR 60·0, P<0·05). The fish was from divergent sources. Five cases had bought the liver from two different butcher's shops, which obtained the lambs' liver from a single abattoir. Consumption of liver is a risk for salmonellosis. Traditional dishes may place some ethnic groups at increased risk of foodborne disease. PMID:17565766

  19. Bottlenecks and Hubs in Inferred Networks Are Important for Virulence in Salmonella typhimurium

    SciTech Connect

    McDermott, Jason E.; Taylor, Ronald C.; Yoon, Hyunjin; Heffron, Fred

    2009-02-01

    Recent advances in experimental methods have provided sufficient data to consider systems as large networks of interconnected components. High-throughput determination of protein-protein interaction networks has led to the observation that topological bottlenecks, that is proteins defined by high centrality in the network, are enriched in proteins with systems-level phenotypes such as essentiality. Global transcriptional profiling by microarray analysis has been used extensively to characterize systems, for example, cellular response to environmental conditions and genetic mutations. These transcriptomic datasets have been used to infer regulatory and functional relationship networks based on co-regulation. We use the context likelihood of relatedness (CLR) method to infer networks from two datasets gathered from the pathogen Salmonella typhimurium; one under a range of environmental culture conditions and the other from deletions of 15 regulators found to be essential in virulence. Bottleneck nodes were identified from these inferred networks and we show that these nodes are significantly more likely to be essential for virulence than their non-bottleneck counterparts. A network generated using Pearson correlation did not display this behavior. Overall this study demonstrates that topology of networks inferred from global transcriptional profiles provides information about the systems-level roles of bottleneck genes. Analysis of the differences between the two CLR-derived networks suggests that the bottleneck nodes are either mediators of transitions between system states or sentinels that reflect the dynamics of these transitions.

  20. Interactions between magainin 2 and Salmonella typhimurium outer membranes: Effect of lipopolysaccharide structure

    SciTech Connect

    Rana, F.R.; Macias, E.A.; Sultany, C.M.; Modzrakowski, M.C.; Blazyk, J. )

    1991-06-18

    The role of the outer membrane and lipopolysaccharide (LPS) in the interaction between the small cationic antimicrobial peptide magainin 2 and the Gram-negative cell envelope was studied by FT-IR spectroscopy. Magainin 2 alters the thermotropic properties of the outer membrane-peptidoglycan complexes from wild-type Salmonella typhimurium and a series of LPS mutants which display differential susceptibility to the bactericidal activity of cationic antibiotics. These results are correlated with the LPS phosphorylation pattern and charge (characterized by high-resolution {sup 31}P NMR) and outer membrane lipid composition, and are compared to the bactericidal susceptibility. LPS mutants show a progressive loss of resistance to killing by magainin 2 as the length of the LPS polysaccharide moiety decreases. Disordering of the outer membrane lipid fatty acyl chains by magainin 2, however, depends primarily upon the magnitude of PLS charge rather than the length of the LPS polysaccharide. While disruption of outer membrane structure most likely is not the primary factor leading to cell death, the susceptibility of Gram-negative cells to magainin 2 is associated with factors that facilitate the transport of the peptide across the outer membrane, such as the magnitude and location of LPS charge, and concentration of LPS in the outer membrane, outer membrane molecular architecture, and the presence or absence of the O-antigen side chain.

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

    SciTech Connect

    Nakayasu, Ernesto S.; Sydor, Michael A.; Brown, Roslyn N.; Sontag, Ryan L.; Sobreira, Tiago; Slysz, Gordon W.; Humphrys, Daniel R.; Skarina, Tatiana; Onoprienko, Olena; Di Leo, Rosa; Kaiser, Brooke LD; Li, Jie; Ansong, Charles; Cambronne, Eric; Smith, Richard D.; Savchenko, Alexei; Adkins, Joshua 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. 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, in addition to the previously reported K63-linked ubiquitin chains. These substrates were further validated by a combination of enzymatic and binding assays. 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.

  2. Neutrophils mediate Salmonella Typhimurium clearance through the GBP4 inflammasome-dependent production of prostaglandins.

    PubMed

    Tyrkalska, Sylwia D; Candel, Sergio; Angosto, Diego; Gómez-Abellán, Victoria; Martín-Sánchez, Fátima; García-Moreno, Diana; Zapata-Pérez, Rubén; Sánchez-Ferrer, Álvaro; Sepulcre, María P; Pelegrín, Pablo; Mulero, Victoriano

    2016-01-01

    Inflammasomes are cytosolic molecular platforms that alert the immune system about the presence of infection. Here we report that zebrafish guanylate-binding protein 4 (Gbp4), an IFNγ-inducible GTPase protein harbouring a C-terminal CARD domain, is required for the inflammasome-dependent clearance of Salmonella Typhimurium (ST) by neutrophils in vivo. Despite the presence of the CARD domain, Gbp4 requires the universal inflammasome adaptor Asc for mediating its antibacterial function. In addition, the GTPase activity of Gbp4 is indispensable for inflammasome activation and ST clearance. Mechanistically, neutrophils are recruited to the infection site through the inflammasome-independent production of the chemokine (CXC motif) ligand 8 and leukotriene B4, and then mediate bacterial clearance through the Gbp4 inflammasome-dependent biosynthesis of prostaglandin D2. Our results point to GBPs as key inflammasome adaptors required for prostaglandin biosynthesis and bacterial clearance by neutrophils and suggest that transient activation of the inflammasome may be used to treat bacterial infections. PMID:27363812

  3. Arylsulfatase in Salmonella typhimurium: detection and influence of carbon source and tyramine on its synthesis.

    PubMed Central

    Henderson, M J; Milazzo, F H

    1979-01-01

    Arylsulfatase synthesis was shown to occur in Salmonella typhimurium LT2. The enzyme had a molecular weight of approximately 50,000 and was separated into five forms by isoelectrofocusing. The optimal pH for substrate hydrolysis was pH 6.7, with Michaelis constants for nitrocatechol sulfate and nitrophenyl sulfate being 4.1 and 7.9 mM, respectively. Enzyme synthesis was strongly influenced by the presence of tyramine in the growth medium. The uptake of [14C]tyramine and arylsulfatase synthesis were initiated during the second phase of a diauxie growth response, when the organism was cultured with different carbon sources. Adenosine 3',5'-cyclic monophosphoric acid enhanced the uptake of tyramine and the levels of arylsulfatase synthesized. However, the addition of glucose and glycerol to organisms actively transporting tyramine and synthesizing enzyme caused a rapid inhibition of both of these processes. This inhibition was not reversed by adding adenosine 3',5'-cyclic monophosphoric acid. The results suggest that the effect of the carbon source on tyramine transport and arylsulfatase synthesis may be explained in terms of inducer exclusion. PMID:222733

  4. Temperate phages promote colicin-dependent fitness of Salmonella enterica serovar Typhimurium.

    PubMed

    Nedialkova, Lubov P; Sidstedt, Maja; Koeppel, Martin B; Spriewald, Stefanie; Ring, Diana; Gerlach, Roman G; Bossi, Lionello; Stecher, Bärbel

    2016-05-01

    Bacteria employ bacteriocins for interference competition in microbial ecosystems. Colicin Ib (ColIb), a pore-forming bacteriocin, confers a significant fitness benefit to Salmonella enterica serovar Typhimurium (S. Tm) in competition against commensal Escherichia coli in the gut. ColIb is released from S. Tm into the environment, where it kills susceptible competitors. However, colicin-specific release proteins, as they are known for other colicins, have not been identified in case of ColIb. Thus, its release mechanism has remained unclear. In the current study, we have established a new link between ColIb release and lysis activity of temperate, lambdoid phages. By the use of phage-cured S. Tm mutant strains, we show that the presence of temperate phages and their lysis genes is necessary and sufficient for release of active ColIb into the culture supernatant. Furthermore, phage-mediated lysis significantly enhanced S. Tm fitness in competition against a ColIb-susceptible competitor. Finally, transduction with the lambdoid phage 933W rescued the defect of E. coli strain MG1655 with respect to ColIb release. In conclusion, ColIb is released from bacteria in the course of phage lysis. Our data reveal a new mechanism for colicin release and point out a novel function of temperate phages in enhancing colicin-dependent bacterial fitness. PMID:26439675

  5. Salmonella Enterica Serovar Typhimurium BipA Exhibits Two Distinct Ribosome Binding Modes

    SciTech Connect

    deLivron, M.; Robinson, V

    2008-01-01

    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 the 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.

  6. Selection of Orphan Rhs Toxin Expression in Evolved Salmonella enterica Serovar Typhimurium

    PubMed Central

    Koskiniemi, Sanna; Garza-Sánchez, Fernando; Sandegren, Linus; Webb, Julia S.; Braaten, Bruce A.; Poole, Stephen J.; Andersson, Dan I.; Hayes, Christopher S.; Low, David A.

    2014-01-01

    Clonally derived bacterial populations exhibit significant genotypic and phenotypic diversity that contribute to fitness in rapidly changing environments. Here, we show that serial passage of Salmonella enterica serovar Typhimurium LT2 (StLT2) in broth, or within a mouse host, results in selection of an evolved population that inhibits the growth of ancestral cells by direct contact. Cells within each evolved population gain the ability to express and deploy a cryptic “orphan” toxin encoded within the rearrangement hotspot (rhs) locus. The Rhs orphan toxin is encoded by a gene fragment located downstream of the “main” rhs gene in the ancestral strain StLT2. The Rhs orphan coding sequence is linked to an immunity gene, which encodes an immunity protein that specifically blocks Rhs orphan toxin activity. Expression of the Rhs orphan immunity protein protects ancestral cells from the evolved lineages, indicating that orphan toxin activity is responsible for the observed growth inhibition. Because the Rhs orphan toxin is encoded by a fragmented reading frame, it lacks translation initiation and protein export signals. We provide evidence that evolved cells undergo recombination between the main rhs gene and the rhs orphan toxin gene fragment, yielding a fusion that enables expression and delivery of the orphan toxin. In this manner, rhs locus rearrangement provides a selective advantage to a subpopulation of cells. These observations suggest that rhs genes play important roles in intra-species competition and bacterial evolution. PMID:24675981

  7. Promoter- and attenuator-related metabolic regulation of the Salmonella typhimurium histidine operon.

    PubMed Central

    Winkler, M E; Roth, D J; Hartman, P E

    1978-01-01

    Expression of the histidine (his) operon in Salmonella typhimurium was found to be positively correlated with the intracellular level of guanosine tetraphosphate (ppGpp). Limitation for amino acids other than histidine elicited a histidine-independent metabolic regulation of the operon. In bacteria grown at decreased growth rates, his operon expression was metabolically regulated up to a point, after which further decreases in growth rate no longer resulted in further enhancement of operon expression. Studies using strains carrying various regulatory and deletion mutations indicated that metabolic regulation is achieved predominantly by increased RNA chain initiations at the primary (P1) and internal (P2) promoters. Metabolic regulation ordinarly did not involve changes in RNA chain terminations at the attenuator site of the his operon. A model is proposed that involves ppGpp-induced changes in RNA polymerase initiation specificity at particular promoters. A second, special form of metabolic regulation may operate which also is histidine independent, but does involve relief of attenuation. PMID:342509

  8. Evidence for an Efflux Pump Mediating Multiple Antibiotic Resistance in Salmonella enterica Serovar Typhimurium

    PubMed Central

    Piddock, Laura J. V.; White, David G.; Gensberg, Karl; Pumbwe, Lilian; Griggs, Deborah J.

    2000-01-01

    The mechanism of multiple antibiotic resistance in six isolates of Salmonella enterica serovar Typhimurium recovered from a patient treated with ciprofloxacin was studied to investigate the role of efflux in the resistance phenotype. Compared to the patient's pretherapy isolate (L3), five of six isolates accumulated less ciprofloxacin, three of six isolates accumulated less chloramphenicol, and all six accumulated less tetracycline. The accumulation of one or more antibiotics was increased by carbonyl cyanide m-chlorophenylhydrazone to concentrations similar to those accumulated by L3 for all isolates except one, in which accumulation of all three agents remained approximately half that of L3. All isolates had the published wild-type sequences of marO and marR. No increased expression of marA, tolC, or soxS was observed by Northern blotting; however, three isolates showed increased expression of acrB, which was confirmed by quantitative competitive reverse transcription-PCR. However, there were no mutations within acrR or the promoter region of acrAB in any of the isolates. PMID:11036033

  9. Branched-chain amino acid biosynthesis in Salmonella typhimurium: a quantitative analysis.

    PubMed

    Epelbaum, S; LaRossa, R A; VanDyk, T K; Elkayam, T; Chipman, D M; Barak, Z

    1998-08-01

    We report here the first quantitative study of the branched-chain amino acid biosynthetic pathway in Salmonella typhimurium LT2. The intracellular levels of the enzymes of the pathway and of the 2-keto acid intermediates were determined under various physiological conditions and used for estimation of several of the fluxes in the cells. The results led to a revision of previous ideas concerning the way in which multiple acetohydroxy acid synthase (AHAS) isozymes contribute to the fitness of enterobacteria. In wild-type LT2, AHAS isozyme I provides most of the flux to valine, leucine, and pantothenate, while isozyme II provides most of the flux to isoleucine. With acetate as a carbon source, a strain expressing AHAS II only is limited in growth because of the low enzyme activity in the presence of elevated levels of the inhibitor glyoxylate. A strain with AHAS I only is limited during growth on glucose by the low tendency of this enzyme to utilize 2-ketobutyrate as a substrate; isoleucine limitation then leads to elevated threonine deaminase activity and an increased 2-ketobutyrate/2-ketoisovalerate ratio, which in turn interferes with the synthesis of coenzyme A and methionine. The regulation of threonine deaminase is also crucial in this regard. It is conceivable that, because of fundamental limitations on the specificity of enzymes, no single AHAS could possibly be adequate for the varied conditions that enterobacteria successfully encounter. PMID:9696751

  10. Thialysine-resistant mutant of Salmonella typhimurium with a lesion in the thrA gene.

    PubMed

    Jegede, V A; Spencer, F; Brenchley, J E

    1976-08-01

    A mutant of Salmonella typhimurium was selected for its spontaneous resistance to the lysine analog, thialysine (S-2-aminoethyl cysteine). This strain, JB585, exhibits a number of pleiotropic properties including a partial growth requirement for threonine, resistance to thiaisoleucine and azaleucine, excretion of lysine and valine, and inhibition of growth by methionine. Genetic studies show that these properties are caused by a single mutation in the thrA gene which encodes the threonine-controlled aspartokinase-homoserine dehydrogenase activities. Enzyme assays demonstrated that the aspartokinase activity is unstable and the threonine-controlled homoserine dehydrogenase activity absent in extracts prepared from the mutant. These results explain the growth inhibition by methionine because the remaining homoserine dehydrogenase isoenzyme would be repressed by methionine, causing a limitation for threonine. The partial growth requirement for threonine during growth in glucose minimal medium may also, by producing an isoleucine limitation, cause derepression of the isoleucine-valine enzymes and provide an explanation for both the valine excretion, and azaleucine and thiaisoleucine resistance. The overproduction of lysine may confer the thialysine resistance. PMID:786777

  11. A comparison of dense transposon insertion libraries in the Salmonella serovars Typhi and Typhimurium

    PubMed Central

    Barquist, Lars; Langridge, Gemma C.; Turner, Daniel J.; Phan, Minh-Duy; Turner, A. Keith; Bateman, Alex; Parkhill, Julian; Wain, John; Gardner, Paul P.

    2013-01-01

    Salmonella Typhi and Typhimurium diverged only ∼50 000 years ago, yet have very different host ranges and pathogenicity. Despite the availability of multiple whole-genome sequences, the genetic differences that have driven these changes in phenotype are only beginning to be understood. In this study, we use transposon-directed insertion-site sequencing to probe differences in gene requirements for competitive growth in rich media between these two closely related serovars. We identify a conserved core of 281 genes that are required for growth in both serovars, 228 of which are essential in Escherichia coli. We are able to identify active prophage elements through the requirement for their repressors. We also find distinct differences in requirements for genes involved in cell surface structure biogenesis and iron utilization. Finally, we demonstrate that transposon-directed insertion-site sequencing is not only applicable to the protein-coding content of the cell but also has sufficient resolution to generate hypotheses regarding the functions of non-coding RNAs (ncRNAs) as well. We are able to assign probable functions to a number of cis-regulatory ncRNA elements, as well as to infer likely differences in tr