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Sample records for attenuated salmonella typhimurium

  1. Anti-angiogenesis Effect on Glioma of Attenuated Salmonella Typhimurium Vaccine Strain with flk-1 Gene

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    冯珂珂; 赵洪洋; 陈剑; 姚东晓; 姜小兵; 周伟

    2004-01-01

    To investigate the anti-vasculature effects and the anti-glioma effects of attenuated Salmonella typhimurium vaccine strain expressing VEGFR2 (flk-1) gene, plasmid pcDNA3. 1-flk1 was constructed and electro-transfected into live attenuated Salmonella typhimurium strain SL7207. Mouse models of intracranial Gl261 glioblastoma were treated with an orally administered attenuated Salmonella typhimurium expressing flk-1 gene. The survival period was recorded and vessel density was observed by immunofluorescence. CTLs activity was measured by MTT assay.Our results showed that attenuated Salmonella typhimurium vaccine strain expressing flk-1 gene could significantly inhibit glioblastoma growth, reduce vessel density, prolong the survival period and improve the survival rate in these mice. The flk-1 specific CTLs activity was increased obviously after the vaccination. Our study showed that attenuated Salmonella typhimurium vaccine strain expressing flk-1 gene could break peripheral immune tolerance a in glioma gainst this self-antigen and kill endothelial cells by the orally administered vaccine and can be used for both prophylactic and therapeutic purposes.

  2. 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

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    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...

  3. Activation and Genetic Modification of Human Monocyte-Derived Dendritic Cells using Attenuated Salmonella typhimurium

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    Agnieszka Michael

    2010-01-01

    Full Text Available Live attenuated bacterial vectors, such as Salmonella typhimurium, have shown promise as delivery vehicles for DNA. We have examined two new strains of S. typhimurium and their impact on dendritic cell maturation (CD12-sifA/aroC mutant and WT05-ssaV/aroC, both in TML background. Strain WT05 matured dendritic cells in a more efficient way; caused higher release of cytokines TNF-α, IL-12, IL-1β; and was efficient for gene transfer. These findings suggest that the genetic background of the attenuation can influence the pattern of inflammatory immune response to Salmonella infection.

  4. Attenuated Salmonella typhimurium SV4089 as a potential carrier of oral DNA vaccine in chickens.

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    Jazayeri, Seyed Davoud; Ideris, Aini; Zakaria, Zunita; Omar, Abdul Rahman

    2012-01-01

    Attenuated Salmonella has been used as a carrier for DNA vaccine. However, in vitro and in vivo studies on the bacteria following transfection of plasmid DNA were poorly studied. In this paper, eukaryotic expression plasmids encoding avian influenza virus (AIV) subtype H5N1 genes, pcDNA3.1/HA, NA, and NP, were transfected into an attenuated Salmonella enteric typhimurium SV4089. In vitro stability of the transfected plasmids into Salmonella were over 90% after 100 generations. The attenuated Salmonella were able to invade MCF-7 (1.2%) and MCF-10A (0.5%) human breast cancer cells. Newly hatched specific-pathogen-free (SPF) chicks were inoculated once by oral gavage with 10(9) colony-forming unit (CFU) of the attenuated Salmonella. No abnormal clinical signs or deaths were recorded after inoculation. Viable bacteria were detected 3 days after inoculation by plating from spleen, liver, and cecum. Fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) were carried out for confirmation. Salmonella was not detected in blood cultures although serum antibody immune responses to Salmonella O antiserum group D1 factor 1, 9, and 12 antigens were observed in all the inoculated chickens after 7 days up to 35 days. Our results showed that live attenuated S. typhimurium SV4089 harboring pcDNA3.1/HA, NA, and NP may provide a unique alternative as a carrier for DNA oral vaccine in chickens.

  5. Cross-protection against Salmonella Typhimurium infection conferred by a live attenuated Salmonella Enteritidis vaccine.

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    Nandre, Rahul M; Lee, Dajeong; Lee, John Hwa

    2015-01-01

    In this study, a genetically engineered live attenuated Salmonella Enteritidis (SE) vaccine was evaluated for its ability to protect against Salmonella Typhimurium (ST) infection in chickens. The birds were orally primed with the vaccine on the 1st day of life and given an oral booster at 5 wk of age. Control birds were orally inoculated with phosphate-buffered saline. Both groups of birds were orally challenged with a virulent ST strain at 9 wk of age. Compared with the control chickens, the vaccinated chickens had significantly higher levels of systemic IgG and mucosal IgA against specific ST antigens and a significantly greater lymphoproliferative response to ST antigens. The excretion of ST into the feces was significantly lower in the vaccinated group than in the control group on days 9 and 13 d after challenge. In addition, the vaccinated group had significantly fewer pronounced gross lesions in the liver and spleen and lower bacterial counts in the internal organs than the control group after challenge. These data indicate that genetically engineered live attenuated SE may induce humoral and cellular immune responses against ST antigens and may confer protection against virulent ST challenge.

  6. Oral attenuated Salmonella typhimurium vaccine against MG7-Ag mimotope of gastric cancer

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    Fan-Ping Meng; Jie Ding; Zhao-Cai Yu; Quan-Li Han; Chang-Cun Guo; Na Liu; Dai-Ming Fan

    2005-01-01

    AIM: To develop an oral attenuated Salmonella typhimurium vaccine against gastric cancer and to evaluate its efficacy in mice.METHODS: A complementary sequence of Nco I site and a sequence coding for MG7-Ag mimotope were designed at the 5' terminus of forward primer. Using p1.2 Ⅱ-HBCAg plasmid as template, PCR was performed to get a fusion gene of the mimotope and a HBcAg gene. The fusion gene was then subcloned into the plasmid pYA3341complementary to Salmonella typhimurium X4550, and the recombinant plasmid was then transformed into attenuated Salmonella typhimurium X4550. Balb/c mice were orally immunized with the recombinant Salmonella typhimurium X4550. The mice were immunized every 2 wk to reinforce the immunity. At the 6th wk, serum titer of antibody was detected by ELISA, and at the 8th wk,cellular immunity was detected by 51Cr release test. Ehrlich ascites carcinoma cells expressing MG7-Ag were used in tumor challenge assay as a model to evaluate the protective effect of the vaccine.RESULTS: Serum titer of antibody against MG7-Ag was significantly higher in mice immunized with the vaccine than in control groups (0.9538±0.043 vs0.6531±0.018,P<0.01; 0.9538±0.043 vs0.6915±0.012, P<0.01), while in vitro 51Cr release assay of the splenocytes showed no statistical difference in the three groups. Two weeks after tumor challenge, 1 in 5 immunized mice was tumor free, while all the mice in the control group presented tumor.CONCLUSION: Oral attenuated Salmonella typhimurium vaccine against the MG7-Ag mimotope of gastric cancer is immunogenic. It can induce significant humoral immunity against tumors in mice, and has some protective effects.

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

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    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.

  8. A novel imageable therapeutic probe for cancer; cytolysin a expressing attenuated salmonella typhimurium

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    Nguyen, Vu Hong; Tae, Seong Ho; Piao, Hong Hua; Hong, Yeoung Jin; Choy, Hyon E.; Bom, Hee Seung; Min, Jung Joon [Chonnam National University Medical School, Gwangju (Korea, Republic of)

    2007-07-01

    Oncolytic strategy using bacteria has a long history. With the discovery of fluorescent and luminescent reporter genes, bacteria can be easily monitored continuously in treatment process. Salmonella typhimurium ppGpp mutant, one of the prominent attenuated bacteria, has just reported recently, Therefore, in this study, we established strain Cytolysin A (Cly A) expressing light-emitting S. typhimurium ppGpp mutant. S. typhimurium ppGpp mutant was transducted by lux gene for in vivo imaging (S. typhimurium ppGpp/lux) and then, plasmid containing ClyA gene, which is encoded for a pore-forming protein toxin, was transformed to create the strain expressing haemolytic activity (S. typhimurium ppGpp/lux/ClyA). The toxicity of ClyA was evaluated in vitro by inoculating the bacteria with various cultured cancer cell lines. On the other hand, to test the therapeutic effect, the bacteria were injected intermittently, intraperitoneal y or intravenously into CT26-bearing Balb/c mice. The sizes of tumors were measured and in vivo imaging was taken everyday by IVIS machine (Xenogen). The in vitro result showed the number of death cells were significantly higher in the samples containing S. typhimurium ppGpp/lux/ClyA compared with the samples containing S. typhimurium ppGpp/lux. After two days injection, the growth of tumors were repressed in mice injected with either S. typhimurium ppGpp/lux/ClyA or S. typhimurium ppGpp/lux, while tumors in control group still grew fast. In day 3, the tumors inoculated with S. typhimurium ppGpp/lux/ClyA became necrosis and regressed in the following days but not in other groups. In addition, in vivo imaging data showed that the Salmonella strains selectively located in the tumor. By in vivo imaging technique, the light-emitting bacteria can be easily monitored and quantified non-invasively and repeatedly. And ClyA expressing light-emitting S. typhimurium ppGpp mutant can become an effective and safely candidate for cancer treatment.

  9. Construction of a recombinant attenuated Salmonella typhimurium DNA vaccine carrying Helicobacter pylori hpaA

    Institute of Scientific and Technical Information of China (English)

    Can Xu; Zhao-Shen Li; Yi-Qi Du; Zhen-Xing Tu; Yan-Fang Gong; Jing Jin; Hong-Yu Wu; Guo-Ming Xu

    2005-01-01

    AIM: To construct a recombinant attenuated Salmonella typhimurium DNA vaccine carrying Helicobacter pylori hpaA gene and to detect its immunogenicity.METHODS: Genomic DNA of the standard H pylori strain 17 874 was isolated as the template, hpaA gene fragment was amplified by polymerase chain reaction (PCR) and cloned into pUCmT vector. DNA sequence of the amplified hpaA gene was assayed, then cloned into the eukaryotic expression vector pIRES through enzyme digestion and ligation reactions. The recombinant plasmid was used to transform competent Escherichia coliDH5α, and the positive clones were screened by PCR and restriction enzyme digestion. Then, the recombinant pIRES-hpaA was used to transform LB5000 and the recombinant plasmid isolated from LB5000 was finally used to transform SL7207. After that, the recombinant strain was grown in vitrorepeatedly. In order to iclentify the immunogenicity of the vaccinein vitro, the recombinant pIRES-hpaA was transfected to COS-7 cells using LipofectamineTM2000, the immunogenicity of expressed HpaA protein was detected with SDS-PAGE and Western blot.RESULTS: The 750-base pair hpaA gene fragment was amplified from the genomic DNA and was consistent with the sequence of H pylori hpaA by sequence analysis. It was confirmed by PCR and restriction enzyme digestion that H pylori hpaA gene was inserted into the eukaryotic expression vector pIRES and a stable recombinant live attenuated Salmonella typhimurium DNA vaccine carrying H pylori hpaA gene was successfully constructed and the specific strip of HpaA expressed by pIRES-hpaA was detected through Western blot.CONCLUSION: The recombinant attenuated Salmonella typhimurium DNA vaccine strain expressing HpaA protein with immunogenicity can be constructed and it may be helpful for further investigating the immune action of DNA vaccine in vivo.

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

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    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

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

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    Sebastian Felgner

    2016-09-01

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

  12. Oral Immunization of Mice With Vaccine of Attenuated Salmonella typhimurium Expressing Helicobacter pylori Urease B Subunit

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    XING-LONG YANG; WEN-CHAO LIU; WU-WEI YANG; DONG ZHONG; YU-HU LIU; JING-DONG ZHANG; JIAN-HUI JIANG; SHAN-SHAN LI

    2005-01-01

    Objective To prepare the live recombinant vaccine of attenuated Salmonella typhimurium SL3261 expressing Helicobacterpylori (H. pylori) B subunit (UreB) and to determine whether it could be used as an oral vaccine against H. pylori infection. Methods Using genomic DNA of H. pylori Sydney strain (SS1) as template, the H. pylori UreB gene fragment was amplified by PCR and subcloned into the expression vector pTC01. The recombinant plasmid pTC01-UreB was then transferred into LB5000 to obtain modified forms, and further conversed into the attenuated Salmonella typhimurium SL3261 to obtain recombinant SL3261/pCT01-UreB as an oral immunization reagent, which was then used to orally immunize Balb/c mice twice at a three-week interval. Twelve weeks later, anti-UreB IgA antibodies in intestinal fluid and IgG antibodies in sera were determined by ELISA. The relating data in control groups (including body weight, gastric inflammation, etc.) were also collected. Results The sequencing analysis showed that the UreB gene fragment amplified by PCR was consistent with the sequence of the H. pylori UreB gene. The restriction enzyme digestion revealed that the correct pTC01-UreB was obtained.SDS-PAGE and Western blot showed that a 61KD protein was expressed in SL3261/pTC01-UreB, which could be recognized by anti-H. pylori UreB antiserum and was absent in the control containing only Salmonella typhimurium SL3261 strain. The multiple oral immunization with SL3261/pTC01-UreB could significantly induce H. pylori specific mucosal IgA response as well as serum IgG responses. IFN-γ and IL-10 levels were significantly increased in SL3261/pTC01-UreB group, and no obvious side effect and change in gastric inflammation were observed. Conclusion The attenuated vaccine of Salmonella typhimurium expressing H. pylori UreB can be used as an oral vaccine against H. pylori infection.

  13. Complete Genome Sequence of NC983, a Live Attenuated Strain of Salmonella enterica Serovar Typhimurium

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    Troxell, Bryan; Fink, Ryan C.; Dickey, Allison N.; Scholl, Elizabeth H.

    2016-01-01

    Foodborne infections caused by Salmonella enterica serovars are a significant problem worldwide. Presented here is the genome sequence of the nontyphoidal S. enterica serovar Typhimurium mutant strain NC983, a potential vaccine candidate. PMID:27738027

  14. Systemic immune responses to oral administration of recombinant attenuated Salmonella typhimurium expressing Helicobacter pyloriurease in mice

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    Xiao-Feng Liu; Jia-Lu Hu; Qi-Zheng Quan; Zi-Qin Sun; Yao-Jun Wang; Feng Qi

    2005-01-01

    AIM: To evaluate whether attenuated Salmonellatyphimurium producing Helicobacter pylori ( H pylori) urease subunit B (UreB) could induce systemic immune responses against H pylori infection.METHODS: Attenuated S. typhimurium SL3261 was used as a live carrier of plasmid pTC01-UreB, which encodes recombinant H pylori UreB protein. Balb/c mice were given oral immunization with two doses of SL3261/pTC01-UreBat a 3-wk interval. Twelve weeks after oral immunization of mice, serum IgG antibodies were evaluated by ELISA assay. Gamma interferon (IFN-γ) and interleukin 10 (IL-10)in the supernatant of spleen cell culture were also assessed by ELISA.RESULTS: After oral immunization of mice, serum specific IgG antibodies against UreB in vaccine group were much higher than that in PBS and native Salmonella SL3261control groups (A450, 0.373±0.100 vs 0.053±0.022, 0.142±0.039, respectively, P<0.01). Moreover, IFN-γ in vaccine group was on average 167.53±29.93 pg/mL, which showed a significant increase vs that of PBS control group (35.68±3.55 pg/mL, P<0.01). There was also a tremendous increase of IL-L0 in vaccine group compared to PBS and SL3261 control groups (275.13±27.65 pg/mL vs 56.00±7.15 pg/mL, 68.02±15.03 pg/mL, respectively, P<0.01). In addition, no obvious side effects in mice and no change in gastric inflammation were observed. CONCLUSION: The multiple oral immunizations with the attenuated S. typhimurium expressing H pylori UreB could induce significant systemic immune responses, suggesting it may be used as oral vaccine against H pylori infection.

  15. Transcription attenuation in Salmonella typhimurium: the significance of rare leucine codons in the leu leader.

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    Carter, P W; Bartkus, J M; Calvo, J M

    1986-11-01

    The leucine operon of Salmonella typhimurium is controlled by a transcription attenuation mechanism. Four adjacent leucine codons within a 160-nucleotide leu leader RNA are thought to play a central role in this mechanism. Three of the four codons are CUA, a rarely used leucine codon within enteric bacteria. To determine whether the nature of the leucine codon affects the regulation of the leucine operon, we used oligonucleotide-directed mutagenesis to first convert one CUA of the leader to CUG and then convert all three CUA codons to CUG. CUG is the most frequently used leucine codon in enteric bacteria. A mutant having (CUA)2CUGCUC in place of (CUA)3CUC has an altered response to leucine limitation, requiring a slightly higher degree of limitation to effect derepression. Changing (CUA)3CUC to (CUG)3CUC has more dramatic effects upon operon expression. First, the basal level of expression is lowered to the point that the mutant grows more slowly than the parent in a minimal medium lacking leucine. Second, the response of the mutant to a leucine limitation is dramatically altered such that even a strong limitation elicits only a modest degree of derepression. If the mutant is grown under conditions of leucyl-tRNA limitation rather than leucine limitation, complete derepression can be achieved, but only at a much higher degree of limitation than for the wild-type operon. These results provide a clear-cut example of codon usage having a dramatic effect upon gene expression.

  16. Construction of attenuated Salmonella typhimurium Strain expressing Helicobacter pylori conservative region of adhesin antigen and its immunogenicity

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    Yang Bai; Ya-Li Zhang; Ji-De Wang; Zhao-Shan Zhang; Dian-Yuan Zhou

    2004-01-01

    AIM: To construct a non-resistant and attenuated Salmonella typhimurium (S. typhimurium) strain which expresses conservative region of adhesion AB of Helicobacter pylori (H pylori) and evaluate its immunogenicity.METHODS: The AB gene amplified by PCR was inserted into the expression vector pYA248 containing asd gene and through two transformations introduced into the delta Cya, delta Crp, delta Asd attenuated Salmonella typhimurium strain, constructing balanced lethal attenuated Salmonella typhimurium strains X4072 (pYA248-AB). Bridged ELISA method was used to measure the expression of AB antigen in sonic ate and culture supernatant. According to the method described by Meacock, stability of the recombinant was evaluated. Semi-lethal capacity test was used to evaluate the safety of recombinant. The immunogenicity of recombinant was evaluated with animal experiments.RESULTS: The attenuated S. typhimurium X4072 (pYA248-AB) which expresses AB was successfully constructed.Furthermore, bridged ELISA assay showed that the content of AB in recombinant X4072 (pYA248- AB) culture supematant was higher than that was in thallus lyric liquor. And after recombinant X4072 (pYA248- AB) was cultured for 100generations without selection pressure, the entire recombinant bacteria selected randomly could grow, and the AB antigen was defected positive by ELISA. The growth curve of the recombinant bacteria showed that the growth states of X4072 (pYA248) and X4072 (pYA248-AB) were basically consistent. The survival rate of C57BL/6 was still 100%, at 30 d after mice taking X4072 (pYA248-AB) 1.0×1010 cfu orally. Oral immunization of mice with X4072 (pYA248-AB)induced a specific immune response.CONCLUSION: In vitro recombinant plasmid appears to be stable and experiments on animals showed that the recombinant strains were safe and immunogenic in vitro,which providing a new live oral vaccine candidate for protection and care of H pylori infection.

  17. Subinhibitory concentrations of phloretin repress the virulence of Salmonella typhimurium and protect against Salmonella typhimurium infection.

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    Shuai-Cheng, Wu; Ben-Dong, Fu; Xiu-Ling, Chu; Jian-Qing, Su; Yun-Xing, Fu; Zhen-Qiang, Cui; Dao-Xiu, Xu; Zong-Mei, Wu

    2016-11-01

    Phloretin, a natural component of many fruits, exhibits anti-virulence effects and provides a new alternative to counter bacterial infection. The aim of this study was to determine the effect of subinhibitory concentrations of phloretin on the virulence of Salmonella typhimurium. At concentrations where growth of Salmonella was not inhibited, phloretin significantly inhibited bacteria biofilm formation and motility. Subinhibitory concentrations of phloretin repressed eight genes involved in the Salmonella pathogenicity island 1 and 3 genes involved in flagella production. Furthermore, subinhibitory concentrations of phloretin inhibited the adhesion and invasion of Salmonella in IEC-6 cells and reduced the LDH levels of S. typhimurium-infected IEC-6 cells. Additionally, phloretin significantly decreased the cecum bacterial loads of the mice infected with live S. typhimurium containing subinhibitory concentrations of phloretin by gavage. These results suggested that subinhibitory concentrations of phloretin attenuate the virulence of S. typhimurium and protect against S. typhimurium infection.

  18. Salmonella enterica serovar typhimurium strains with regulated delayed attenuation in vivo.

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    Curtiss, Roy; Wanda, Soo-Young; Gunn, Bronwyn M; Zhang, Xin; Tinge, Steven A; Ananthnarayan, Vidya; Mo, Hua; Wang, Shifeng; Kong, Wei

    2009-03-01

    Recombinant bacterial vaccines must be fully attenuated for animal or human hosts to avoid inducing disease symptoms while exhibiting a high degree of immunogenicity. Unfortunately, many well-studied means for attenuating Salmonella render strains more susceptible to host defense stresses encountered following oral vaccination than wild-type virulent strains and/or impair their ability to effectively colonize the gut-associated and internal lymphoid tissues. This thus impairs the ability of recombinant vaccines to serve as factories to produce recombinant antigens to induce the desired protective immunity. To address these problems, we designed strains that display features of wild-type virulent strains of Salmonella at the time of immunization to enable strains first to effectively colonize lymphoid tissues and then to exhibit a regulated delayed attenuation in vivo to preclude inducing disease symptoms. We recently described one means to achieve this based on a reversible smooth-rough synthesis of lipopolysaccharide O antigen. We report here a second means to achieve regulated delayed attenuation in vivo that is based on the substitution of a tightly regulated araC P(BAD) cassette for the promoters of the fur, crp, phoPQ, and rpoS genes such that expression of these genes is dependent on arabinose provided during growth. Thus, following colonization of lymphoid tissues, the Fur, Crp, PhoPQ, and/or RpoS proteins cease to be synthesized due to the absence of arabinose such that attenuation is gradually manifest in vivo to preclude induction of diseases symptoms. Means for achieving regulated delayed attenuation can be combined with other mutations, which together may yield safe efficacious recombinant attenuated Salmonella vaccines.

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

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    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.

  20. Construction of recombinant attenuated Salmonella typhimurium DNA vaccine expressing H pylori ureB and IL-2

    Institute of Scientific and Technical Information of China (English)

    Can Xu; Zhao-Shen Li; Yi-Qi Du; Yan-Fang Gong; Hua Yang; Bo Sun; Jing Jin

    2007-01-01

    AIM: To construct a recombinant live attenuated Salmonella typhimurium DNA vaccine encoding H pylori ureB gene and mouse IL-2 gene and to detect its immunogenicity in vitro and in vivo.METHODS: H pylori ureB and mouse IL-2 gene fragments were amplified by potymerase chain reaction (PCR) and cloned into pUCmT vector. DNA sequence of the amplified ureB and IL-2 genes was assayed, then cloned into the eukaryotic expression vector pIRES through enzyme digestion and ligation reactions resulting in pIRES-ureB and pIRES-ureB-IL-2. The recombinant plasmids were used to transform competent E. Coli DH5a, and the positive clones were screened by PCR and restriction enzyme digestion. Then, the recombinant pIRES-ureB and pIRES-ureB-IL-2 were used to transform LB5000 and the recombinant plasmids extracted from LB5000 were finally introduced into the final host SL7207. After that, recombinant strains were grown in vitro repeatedly. In order to detect the immunogenicity of the vaccine in vitro, pIRES-ureB and pIRES-ureB-IL-2 were transfected to COS-7 cells using Lipofectamine TM 2000, the immunogenicity of expressed UreB and IL-2 proteins was assayed with SDS-PAGE and Western blot. C57BL/6 mice were orally immunized with 1 x 108 recombinant attenuated Salmonella typhimurium DNA vaccine. Four weeks after vaccination, mice were challenged with 1 x 107 CFU of live Hpylori SSI. Mice were sacrificed and the stomach was isolated for examination of H pylori 4 wk post-challenge.RESULTS: The 1700 base pair ureB gene fragment amplified from the genomic DNA was consistent with the sequence of H pylori ureB by sequence analysis. The amplified 510 base pair fragment was consistent with the sequence of mouse IL-2 in gene bank. It was confirmed by PCR and restriction enzyme digestion that H pylori ureB and mouse IL-2 genes were inserted into the eukaryotic expression vector pIRES. The experiments in vitro snowed that stable recombinant live attenuated Salmonella typhimurium DNA vaccine carrying

  1. Targeted Cancer Therapy Using Engineered Salmonella typhimurium.

    Science.gov (United States)

    Zheng, Jin Hai; Min, Jung-Joon

    2016-09-01

    Obligate or facultative anaerobic bacteria such as Bifidobacterium, Clostridium, Salmonella, or Escherichia coli specifically colonize and proliferate inside tumor tissues and inhibit tumor growth. Among them, attenuated Salmonella typhimurium (S. typhimurium) has been widely studied in animal cancer models and Phase I clinical trials in human patients. S. typhimurium genes are easily manipulated; thus diverse attenuated strains of S. typhimurium have been designed and engineered as tumor-targeting therapeutics or drug delivery vehicles that show both an excellent safety profile and therapeutic efficacy in mouse models. An attenuated strain of S. typhimurium, VNP20009, successfully targeted human metastatic melanoma and squamous cell carcinoma in Phase I clinical trials; however, the efficacy requires further refinement. Along with the characteristics of self-targeting, proliferation, and deep tissue penetration, the ease of genetic manipulation allows for the production of more attenuated strains with greater safety profiles and vector systems that deliver designable cargo molecules for cancer diagnosis and/or therapy. Here, we discuss recent progress in the field of Salmonellae-mediated cancer therapy.

  2. Targeted Cancer Therapy Using Engineered Salmonella typhimurium

    Science.gov (United States)

    Zheng, Jin Hai

    2016-01-01

    Obligate or facultative anaerobic bacteria such as Bifidobacterium, Clostridium, Salmonella, or Escherichia coli specifically colonize and proliferate inside tumor tissues and inhibit tumor growth. Among them, attenuated Salmonella typhimurium (S. typhimurium) has been widely studied in animal cancer models and Phase I clinical trials in human patients. S. typhimurium genes are easily manipulated; thus diverse attenuated strains of S. typhimurium have been designed and engineered as tumor-targeting therapeutics or drug delivery vehicles that show both an excellent safety profile and therapeutic efficacy in mouse models. An attenuated strain of S. typhimurium, VNP20009, successfully targeted human metastatic melanoma and squamous cell carcinoma in Phase I clinical trials; however, the efficacy requires further refinement. Along with the characteristics of self-targeting, proliferation, and deep tissue penetration, the ease of genetic manipulation allows for the production of more attenuated strains with greater safety profiles and vector systems that deliver designable cargo molecules for cancer diagnosis and/or therapy. Here, we discuss recent progress in the field of Salmonellae-mediated cancer therapy. PMID:27689027

  3. Liver and circulating NK1.1(+)CD3(-) cells are increased in infection with attenuated Salmonella typhimurium and are associated with reduced tumor in murine liver cancer.

    Science.gov (United States)

    Feltis, B A; Miller, J S; Sahar, D A; Kim, A S; Saltzman, D A; Leonard, A S; Wells, C L; Sielaff, T D

    2002-09-01

    An attenuated (DeltacyA, Deltacrp) strain of Salmonella typhimurium (chi4550) containing a gene for human IL-2 (chi4550pIL2) reduces hepatic tumor burden when orally inoculated into mice with liver cancer; however, wild-type S. typhimurium is also associated with cancer regression. Therefore, experiments were designed to clarify the invasiveness and the anti-tumor properties of three strains of S. typhimurium. S. typhimurium chi4550pIL2, chi4550, or wild type (WT) was incubated with mature Caco-2 and HT-29 enterocytes, and S. typhimurium internalization was assessed. For infectivity experiments, mice were orally inoculated with saline or 10(9)S. typhimurium chi4550pIL2, chi4550, or WT; 48 h later mice were sacrificed for analysis of cecal bacteria and S. typhimurium translocation to mesenteric lymph nodes. For experiments involving tumor implantation, four groups were studied: saline control, tumor alone, chi4550pIL2+tumor, and chi4550+tumor. Mice were orally inoculated with saline or S. typhimurium and underwent laparotomy 24 h later with 5 x 10(4) MCA38 murine adenocarcinoma cells injected into the spleen. On day 14, liver tumors were counted and peripheral blood and hepatic lymphocyte populations were analyzed by FACScan. Attenuated S. typhimurium exhibited decreased internalization by cultured enterocytes and decreased infectivity after oral inoculation. Mice treated with chi4550pIL2 or chi4550 had fewer liver tumors and increased populations of hepatic and circulating NK1.1(+)CD3(-) lymphocytes compared to mice treated with saline (P < 0.01). These data suggest that attenuated S. typhimurium may have an application as an anti-tumor agent.

  4. Immune responses to a recombinant attenuated Salmonella typhimurium strain expressing a Taenia solium oncosphere antigen TSOL18.

    Science.gov (United States)

    Ding, Juntao; Zheng, Yadong; Wang, Ying; Dou, Yongxi; Chen, Xiaoyu; Zhu, Xueliang; Wang, Shuai; Zhang, Shaohua; Liu, Zhenyong; Hou, Junling; Zhai, Junjun; Yan, Hongbin; Luo, Xuenong; Cai, Xuepeng

    2013-01-01

    A tapeworm, Taenia solium, remains a great threat to human health, particularly in developing countries. The life cycle of T. solium is thought to be terminated via vaccination of intermediate hosts. In this study, we constructed a recombinant attenuated Salmonella typhimurium live vaccine strain χ4558 expressing a TSOL18 antigen. SDS-PAGE and Western blot confirmed the expression of the interest protein and its antigenic property. The recombinant strain stably propagated in vitro, of which the growth was not reversely influenced by TSOL18 protein expressed. It was also shown that mice survived 10(12) CFU of S. typhimurium χ4558, while all mice infected with 10(7) CFU of the wild-type died within five days. The mouse experiment indicated that vaccine strain χ4558 induced a high titer of specific antibody for a long time. In contrast to the controls, the vaccinated mice had an obvious augment of CD4(+) and CD8(+) T lymphocytes and the percentage of helper CD4(+)/CD8(+) T lymphocytes was significantly increased (psolium.

  5. Immunogenicity of recombinant attenuated Salmonella enterica serovar Typhimurium vaccine strains carrying a gene that encodes Eimeria tenella antigen SO7.

    Science.gov (United States)

    Konjufca, Vjollca; Jenkins, Mark; Wang, Shifeng; Juarez-Rodriguez, Maria Dolores; Curtiss, Roy

    2008-12-01

    Recombinant attenuated Salmonella vaccines against avian coccidiosis were developed to deliver Eimeria species antigens to the lymphoid tissues of chickens via the type 3 secretion system (T3SS) and the type 2 secretion system (T2SS) of Salmonella. For antigen delivery via the T3SS, the Eimeria tenella gene encoding sporozoite antigen SO7 was cloned downstream of the translocation domain of the Salmonella enterica serovar Typhimurium sopE gene in the parental pYA3868 and pYA3870 vectors to generate pYA4156 and pYA4157. Newly constructed T3SS vectors were introduced into host strain chi8879 (Delta phoP233 Delta sptP1033::xylE Delta asdA16), an attenuated derivative of the highly virulent UK-1 strain. The SopE-SO7 fusion protein was secreted by the T3SS of Salmonella. The vector pYA4184 was constructed for delivery of the SO7 antigen via the T2SS. The SO7 protein was toxic to Salmonella when larger amounts were synthesized; thus, the synthesis of this protein was placed under the control of the lacI repressor gene, whose expression in turn was dependent on the amount of available arabinose in the medium. The pYA4184 vector was introduced into host strain chi9242 (Delta phoP233 Delta asdA16 Delta araBAD23 Delta relA198::araC P(BAD) lacI TT [TT is the T4ipIII transcription terminator]). In addition to SO7, for immunization and challenge studies we used the EAMZ250 antigen of Eimeria acervulina, which was previously shown to confer partial protection against E. acervulina challenge when it was delivered via the T3SS. Immunization of chickens with a combination of the SO7 and EAMZ250 antigens delivered via the T3SS induced superior protection against challenge by E. acervulina. In contrast, chickens immunized with SO7 that was delivered via the T2SS of Salmonella were better protected from challenge by E. tenella.

  6. Specific anti-tumor effect induced by attenuated Salmonella typhimurium vaccine expressing extracellular region of vascular endothelial growth factor receptor 2

    Institute of Scientific and Technical Information of China (English)

    YANG Jun; DONG Jian; PU Ping; WANG ZhiQiang; HONG Min; CHEN MingQing

    2008-01-01

    The purposes of this research were to study the stable expression of exogenous gene encoding therapeutic protein in attenuated Salmonella typhimurium, observe the metabolism of oral gene vac-cine carried by attenuated Salmonella typhimurium in BALB/c mouse, and investigate the feasibility of prevention and treatment of tumors by the recombinant bacteria. Recombinant plasmid pcDNA3.1+ VEGFR2(n1-7) was transformed into competent attenuated Salmonella typhimurium SL3261 to develop oral DNA vaccine SL3261-pcDNA3.1+VEGFR2(n1-7). To observe whether the exogenous gene can be ex-pressed in the recombinant bacteria, PCR was performed to amplify the CMV promoter of the eu-karyotic expression vector as the proof of stable expression of exogenous protein; transmission elec-tron microscopy (TEM) was applied to observe the morphology of the recombinant bacteria to confirm that the exogenous gene has no impact on the growth of the bacteria, and then BALB/c mice were immunized with the gene vaccine. After inoculation of the gene vaccine, the recombinant bacteria SL3261 could be detected in the tissues such as small intestine, colon, liver and spleen. And then, mice in each group were challenged with tumor cells. The results of animal experiment showed that tumor growth of the mice in experimental group was inhibited and survival time of immunized mice was pro-longed compared with control groups. A higher lymphocyte infiltration in tumors from animals treated with DNA vaccine was observed. Immunohistochemical analysis of tumor samples revealed an en-hanced accumulation of CD8+ cytotoxic T lymphocytes, as well as an increase in CD4+ cells in the tu-mors of animals treated with the oral gene vaccine compared to tumors from control group mice. UI-trastructure of the tumor tissue showed that tumor cells in the samples of the immunized mice were well-differentiated. Our research confirmed that the exogenous gene can be stably expressed in the attenuated Salmonella typhimurium and has no

  7. Immune responses in mice to oral administration of attenuated Salmonella typhimurium expressing Helicobacter pylori urease B subunit by a lavage technique

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-feng; LIU Chang-jiang; HU Jia-lu; JIA Ai-qin; SUN Zi-qin

    2006-01-01

    Objective:To determine whether attenuated Salmonella typhimurium producing Helicobacter pylori (Hp) urease subunit B(UreB)can elicit specific immune responses against Hp in mice tested by a lavage technique. Methods: Attenuated Salmonella typhimurium producing Hp UreB immunized orally Balb/c mice twice at a 3-week interval. After 12 weeks,mice intestinal secretions were obtained without harm by administering a lavage solution intragastrically.The mice intestinal secretions of immune group were also directly washed out after the mice were killed. The antibody responses were evaluated by using serum and intestinal fluid with ELISA assay. Results: The multiple oral immunizations with SL3261/pTC01 UreB induced significantly Hp-specific mucosal IgA response as well as serum IgG response. The IgA was also consistently higher in the intestinal fluid obtained by the lavage solution than by direct washout. In addition, no obvious side effects and changes in gastric inflammation were observed in mice.Conclusion: The attenuated Salmonella typhimurium expressing Hp UreB may be used as an oral vaccine against Hp infection. And the lavage technique is an ideal method in the study of mucosal immune responses.

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

    Science.gov (United States)

    Carey, Christine M; Kostrzynska, Magdalena

    2013-01-01

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

  9. Live attenuated vaccines for invasive Salmonella infections.

    Science.gov (United States)

    Tennant, Sharon M; Levine, Myron M

    2015-06-19

    Salmonella enterica serovar Typhi produces significant morbidity and mortality worldwide despite the fact that there are licensed Salmonella Typhi vaccines available. This is primarily due to the fact that these vaccines are not used in the countries that most need them. There is growing recognition that an effective invasive Salmonella vaccine formulation must also prevent infection due to other Salmonella serovars. We anticipate that a multivalent vaccine that targets the following serovars will be needed to control invasive Salmonella infections worldwide: Salmonella Typhi, Salmonella Paratyphi A, Salmonella Paratyphi B (currently uncommon but may become dominant again), Salmonella Typhimurium, Salmonella Enteritidis and Salmonella Choleraesuis (as well as other Group C Salmonella). Live attenuated vaccines are an attractive vaccine formulation for use in developing as well as developed countries. Here, we describe the methods of attenuation that have been used to date to create live attenuated Salmonella vaccines and provide an update on the progress that has been made on these vaccines.

  10. An altered immune response, but not individual cationic antimicrobial peptides, is associated with the oral attenuation of Ara4N-deficient Salmonella enterica serovar Typhimurium in mice.

    Directory of Open Access Journals (Sweden)

    Kristi L Strandberg

    Full Text Available Salmonella enterica serovar Typhimurium (S. Typhimurium uses two-component regulatory systems (TCRS to respond to stimuli in the local microenvironment. Upon infection, the Salmonella TCRSs PhoP-PhoQ (PhoPQ and PmrA-PmrB (PmrAB are activated by environmental signals in the intestinal lumen and within host cells. TCRS-mediated gene expression results in lipopolysaccharide (LPS modification and cationic antimicrobial peptide resistance. The PmrA-regulated pmrHFIJKLM operon mediates 4-amino-4-deoxy-L-arabinose (Ara4N production and attachment to the lipid A of LPS. A ΔpmrF S. Typhimurium strain cannot produce Ara4N, exhibits increased sensitivity to cationic antimicrobial peptide (CAMP-mediated killing, and attenuated virulence in mice upon oral infection. CAMPs are predicted to play a role in elimination of Salmonella, and may activate PhoPQ and PmrAB in vivo, which could increase bacterial resistance to host defenses. Competition experiments between wild type (WT and ΔpmrF mutant strains of S. Typhimurium indicated that selection against this mutant first occurs within the intestinal lumen early during infection. However, CRAMP and active cryptdins alone are not responsible for elimination of Ara4N-deficient bacteria in vivo. Investigation into the early immune response to ΔpmrF showed that it differed slightly from the early immune response to WT S. Typhimurium. Further investigation into the early immune response to infection of Peyer's patches suggests a role for IL-13 in the attenution of the ΔpmrF mutant strain. Thus, prominent CAMPs present in the mouse intestine are not responsible for the selection against the ΔpmrF strain in this location, but limited alterations in innate immune induction were observed that affect bacterial survival and virulence.

  11. Salmonella Typhimurium infection primes a nutriprive mechanism in piglets.

    Science.gov (United States)

    Miarelli, Maria; Drumo, Rosanna; Signorelli, Federica; Marchitelli, Cinzia; Pavone, Silvia; Pesciaroli, Michele; Ruggieri, Jessica; Chirullo, Barbara; Ammendola, Serena; Battistoni, Andrea; Alborali, Giovanni L; Manuali, Elisabetta; Pasquali, Paolo

    2016-04-15

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important cause of acute food- borne zoonoses worldwide, typically carried by pigs. It is well known that Salmonella has evolved a wide array of strategies enabling it to invade the host, but little information is available on the specific host responses to Salmonella infections. In the present study, we used an in vivo approach (involving piglets infected with a virulent or an attenuated S. Typhimurium strain) coupled to histological and proteomic analysis of the cecum mucosa, to highlight the host pathways activated during S. Typhimurium infection. We confirm the complex host-pathogen interaction. Our data showed that the metabolic and the cytoskeleton organization functions were the most significantly altered. In particular, the modifications of energy metabolic pathway could suggest a "nutriprive" mechanism, in which the host reduce its metabolic and energetic status to limit Salmonella infection. This study could represent a preliminary approach, providing information useful to better understand the host-Salmonella interaction.

  12. Attenuated Salmonella typhimurium delivering DNA vaccine encoding duck enteritis virus UL24 induced systemic and mucosal immune responses and conferred good protection against challenge

    Directory of Open Access Journals (Sweden)

    Yu Xia

    2012-07-01

    Full Text Available Abstract Orally delivered DNA vaccines against duck enteritis virus (DEV were developed using live attenuated Salmonella typhimurium (SL7207 as a carrier and Escherichia coli heat labile enterotoxin B subunit (LTB as a mucosal adjuvant. DNA vaccine plasmids pVAX-UL24 and pVAX-LTB-UL24 were constructed and transformed into attenuated Salmonella typhimurium SL7207 resulting SL7207 (pVAX-UL24 and SL7207 (pVAX-LTB-UL24 respectively. After ducklings were orally inoculated with SL7207 (pVAX-UL24 or SL7207 (pVAX-LTB-UL24, the anti-DEV mucosal and systemic immune responses were recorded. To identify the optimum dose that confers maximum protection, we used different doses of the candidate vaccine SL7207 (pVAX-LTB-UL24 during oral immunization. The strongest mucosal and systemic immune responses developed in the SL7207 (pVAX-LTB-UL24 (1011 CFU immunized group. Accordingly, oral immunization of ducklings with SL7207 (pVAX-LTB-UL24 showed superior efficacy of protection (60-80% against a lethal DEV challenge (1000 LD50, compared with the limited survival rate (40% of ducklings immunized with SL7207 (pVAX-UL24. Our study suggests that the SL7207 (pVAX-LTB-UL24 can be a candidate DEV vaccine.

  13. Oral Vaccination with Attenuated Salmonella typhimurium-Delivered TsPmy DNA Vaccine Elicits Protective Immunity against Trichinella spiralis in BALB/c Mice

    Science.gov (United States)

    Wang, Lei; Wang, Xiaohuan; Bi, Kuo; Sun, Ximeng; Yang, Jing; Gu, Yuan; Huang, Jingjing; Zhan, Bin; Zhu, Xinping

    2016-01-01

    Background Our previous studies showed that Trichinella spiralis paramyosin (TsPmy) is an immunomodulatory protein that inhibits complement C1q and C8/C9 to evade host complement attack. Vaccination with recombinant TsPmy protein induced protective immunity against T. spiralis larval challenge. Due to the difficulty in producing TsPmy as a soluble recombinant protein, we prepared a DNA vaccine as an alternative approach in order to elicit a robust immunity against Trichinella infection. Methods and Findings The full-length TsPmy coding DNA was cloned into the eukaryotic expression plasmid pVAX1, and the recombinant pVAX1/TsPmy was transformed into attenuated Salmonella typhimurium strain SL7207. Oral vaccination of mice with this attenuated Salmonella-delivered TsPmy DNA vaccine elicited a significant mucosal sIgA response in the intestine and a systemic IgG antibody response with IgG2a as the predominant subclass. Cytokine analysis also showed a significant increase in the Th1 (IFN-γ, IL-2) and Th2 (IL-4, 5, 6, 10) responses in lymphocytes from the spleen and MLNs of immunized mice upon stimulation with TsPmy protein. The expression of the homing receptors CCR9/CCR10 on antibody secreting B cells may be related to the translocation of IgA-secreted B cells to local intestinal mucosa. The mice immunized with Salmonella-delivered TsPmy DNA vaccine produced a significant 44.8% reduction in adult worm and a 46.6% reduction in muscle larvae after challenge with T. spiralis larvae. Conclusion Our results demonstrated that oral vaccination with TsPmy DNA delivered by live attenuated S. typhimurium elicited a significant local IgA response and a mixed Th1/Th2 immune response that elicited a significant protection against T. spiralis infection in mice. PMID:27589591

  14. 9 CFR 113.120 - Salmonella Typhimurium Bacterin.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Salmonella Typhimurium Bacterin. 113... REQUIREMENTS Inactivated Bacterial Products § 113.120 Salmonella Typhimurium Bacterin. Salmonella Typhimurium Bacterin shall be prepared from a culture of Salmonella typhimurium which has been inactivated and...

  15. An oral DNA vaccine against MG7—Ag of gastric cancer using attenuated Salmonella typhimurium as carrier

    Institute of Scientific and Technical Information of China (English)

    ChangCunGuo; JieDing; 等

    2002-01-01

    Aims:To develop an oral DNA vaccine against gastric cancer and evaluate its efficacy in mice.Methods:The gene of the MG7-Ag mimotope and a universal Th epitop (Pan-DR epitope,PADRE) were included in the PCR primers.By PCR,the fusion gene of the two epitopes was amplified.The fusion gene was confirmed by sequencing and then cloned into pcDNA3.1(+) plasmid.The pcDNA3.1(+)-MG7/PADRE was used to transfect an anttenuatedf Salmonella typhimurium.C57BL/6 mice were orally immunized uated Salmonella typhimurium.C57BL/6 micr were orally immunized with 1×108 cfu Salmonella transfectants.Salmonella harboring the empty pcDNA3.1(+) plasmid and phosphate buffer saline (PBS) were used as negative control.At the 6th week,serum titer of MG7-Ag specific antibody was detected by ELISA.at the 8th week cellular immunity was detected by an unprimed proliferation test of the spleenocytes by using a [3H]-thymidine incorporation assay.Ehrlich ascites carcinoma cells expressing MG7-Ag were used as a model in tumor challenge assay to evaluate the protective of the vaccine.Results:Serum titer of antibody against MG7-Ag was significantly higher in mice immunized with the vaccine than control groups (0.841 vs 0.374,P<0.01;0.841 vs 0.298,P<0.01),while exvivo unprimed proliferation assay of the spleenocytes showed no statistical difference between those three groups.Two weeks after tumor challenge,2 in 7 immunized mice were tumor free,while all the mice in the control groups showed tumor formation.Conclusions:Oral DNA vaccine against the MG7-Ag mimotope of gastric cancer is immunogenic.It can induce significant humoral immunity against tumor in mice,and the vaccine has partially protective effects.

  16. Salmonella enterica serovar typhimurium trxA mutants are protective against virulent challenge and induce less inflammation than the live-attenuated vaccine strain SL3261.

    Science.gov (United States)

    Peters, S E; Paterson, G K; Bandularatne, E S D; Northen, H C; Pleasance, S; Willers, C; Wang, J; Foote, A K; Constantino-Casas, F; Scase, T J; Blacklaws, B A; Bryant, C E; Mastroeni, P; Charles, I G; Maskell, D J

    2010-01-01

    In Salmonella enterica serovar Typhimurium, trxA encodes thioredoxin 1, a small, soluble protein with disulfide reductase activity, which catalyzes thiol disulfide redox reactions in a variety of substrate proteins. Thioredoxins are involved as antioxidants in defense against oxidative stresses, such as exposure to hydrogen peroxide and hydroxyl radicals. We have made a defined, complete deletion of trxA in the mouse-virulent S. Typhimurium strain SL1344 (SL1344 trxA), replacing the gene with a kanamycin resistance gene cassette. SL1344 trxA was attenuated for virulence in BALB/c mice by the oral and intravenous routes and when used in immunization experiments provided protection against challenge with the virulent parent strain. SL1344 trxA induced less inflammation in murine spleens and livers than SL3261, the aroA mutant, live attenuated vaccine strain. The reduced splenomegaly observed following infection with SL1344 trxA was partially attributed to a reduction in the number of both CD4(+) and CD8(+) T cells and B lymphocytes in the spleen and reduced infiltration by CD11b(+) cells into the spleen compared with spleens from mice infected with SL3261. This less severe pathological response indicates that a trxA mutation might be used to reduce reactogenicity of live attenuated vaccine strains. We tested this by deleting trxA in SL3261. SL3261 trxA was also less inflammatory than SL3261 but was slightly less effective as a vaccine strain than either the SL3261 parent strain or SL1344 trxA.

  17. Mice Are Protected from Helicobacter pylori Infection by Nasal Immunization with Attenuated Salmonella typhimurium phoPc Expressing Urease A and B Subunits

    OpenAIRE

    Corthésy-Theulaz, Irène E.; Hopkins, Sally; Bachmann, Daniel; Saldinger, Pierre F; Porta, Nadine; Haas, Rainer; Zheng-Xin, Yan; Meyer, Thomas; Bouzourène, Hanifa; Blum, André L.; Kraehenbuhl, Jean-Pierre

    1998-01-01

    Live Salmonella typhimurium phoPc bacteria were tested as mucosal vaccine vectors to deliver Helicobacter pylori antigens. The genes encoding the A and B subunits of H. pylori urease were introduced into S. typhimurium phoPc and expressed under the control of a constitutive tac promoter (tac-ureAB) or a two-phase T7 expression system (cT7-ureAB). Both recombinant Salmonella strains expressed the two urease subunits in vitro and were used to nasally immunize BALB/c mice. The plasmid carrying c...

  18. Salmonella Typhimurium infection in the porcine intestine

    DEFF Research Database (Denmark)

    Schauser, Kirsten; Olsen, John Elmerdahl; Larsson, Lars-Inge

    2005-01-01

    The normal intestinal epithelium is renewed with a turnover rate of 3-5 days. During Salmonella infection increased cell loss is observed, possibly as a result of programmed cell death (PCD). We have, therefore, studied the effects of Salmonella Typhimurium infection on three elements involved...... in scattered epithelial cells and the number of positive cells increased with increasing times of exposure to Salmonella (P

  19. 40 CFR 79.68 - Salmonella typhimurium reverse mutation assay.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Salmonella typhimurium reverse... Registration § 79.68 Salmonella typhimurium reverse mutation assay. (a) Purpose. The Salmonella typhimurium... chemicals which cause base changes or frameshift mutations in the genome of the microorganism...

  20. Regulated delayed expression of rfaH in an attenuated Salmonella enterica serovar typhimurium vaccine enhances immunogenicity of outer membrane proteins and a heterologous antigen.

    Science.gov (United States)

    Kong, Qingke; Liu, Qing; Roland, Kenneth L; Curtiss, Roy

    2009-12-01

    RfaH is a transcriptional antiterminator that reduces the polarity of long operons encoding secreted and surface-associated cell components of Salmonella enterica serovar Typhimurium, including O antigen and lipopolysaccharide core sugars. A DeltarfaH mutant strain is attenuated in mice (50% lethal dose [LD(50)], >10(8) CFU). To examine the potential for using rfaH in conjunction with other attenuating mutations, we designed a series of strains in which we replaced the native rfaH promoter with the tightly regulated arabinose-dependent araC P(BAD) promoter so that rfaH expression was dependent on exogenously supplied arabinose provided during in vitro growth. Following colonization of host lymphoid tissues, where arabinose was not available, the P(BAD) promoter was no longer active and rfaH was not expressed. In the absence of RfaH, O antigen and core sugars were not synthesized. We constructed three mutant strains that expressed different levels of RfaH by altering the ribosome-binding sequence and start codon. One mutation, DeltaP(rfaH178), was introduced into the attenuated vaccine strain chi9241 (DeltapabA DeltapabB DeltaasdA) expressing the pneumococcal surface protein PspA from an Asd(+) balanced-lethal plasmid. Mice immunized with this strain and boosted 4 weeks later induced higher levels of serum immunoglobulin G specific for PspA and for outer membrane proteins from other enteric bacteria than either an isogenic DeltarfaH derivative or the isogenic RfaH(+) parent. Eight weeks after primary oral immunization, mice were challenged with 200 LD(50) of virulent Streptococcus pneumoniae WU2. Immunization with DeltaP(rfaH178) mutant strains led to increased levels of protection compared to that of the parent chi9241 and of a DeltarfaH derivative of chi9241.

  1. Safety and immunogenicity of an oral DNA vaccine encoding Sip of Streptococcus agalactiae from Nile tilapia Oreochromis niloticus delivered by live attenuated Salmonella typhimurium.

    Science.gov (United States)

    Huang, L Y; Wang, K Y; Xiao, D; Chen, D F; Geng, Y; Wang, J; He, Y; Wang, E L; Huang, J L; Xiao, G Y

    2014-05-01

    Attenuated Salmonella typhimurium SL7207 was used as a carrier for a reconstructed DNA vaccine against Streptococcus agalactiae. A 1.02 kb DNA fragment, encoding for a portion of the surface immunogenic protein (Sip) of S. agalactiae was inserted into pVAX1. The recombinant plasmid pVAX1-sip was transfected in EPC cells to detect the transient expression by an indirect immunofluorescence assay, together with Western blot analysis. The pVAX1-sip was transformed by electroporation into SL7207. The stability of pVAX1-sip into Salmonella was over 90% after 50 generations with antibiotic selection in vitro while remained stable over 80% during 35 generations under antibiotic-free conditions. The LD50 of SL/pVAX1-sip was 1.7 × 10(11) CFU/fish by intragastric administration which indicated a quite low virulence. Tilapias were inoculated orally at 10(8) CFU/fish, the recombinant bacteria were found present in intestinal tract, spleens and livers and eventually eliminated from the tissues 4 weeks after immunization. Fish immunized at 10(7), 10(8) and 10(9) CFU/fish with different immunization times caused various levels of serum antibody and an effective protection against lethal challenge with the wild-type strain S. agalactiae. Integration studies showed that the pVAX1-sip did not integrate with tilapia chromosomes. The DNA vaccine SL/pVAX1-sip was proved to be safe and effective in protecting tilapias against S. agalactiae infection.

  2. Development of an oral DNA vaccine against MG7-Ag of gastric cancer using attenuated salmonella typhimurium as carrier

    Institute of Scientific and Technical Information of China (English)

    Chang-Cun Guo; Jie Ding; Bo-Rong Pan; Zhao-Cai Yu; Quan-Li Han; Fan-Ping Meng; Na Liu; Dai-Ming Fan

    2003-01-01

    AIM: To develop an oral DNA vaccine against gastric cancer and evaluate its efficacy in mice.METHODS: The genes of the MG7-Ag mimotope and a universal Th epitope (Pan-DR epitope, PADRE) were included in the PCR primers. By PCR, the fusion gene of the two epitopes was amplified. The fusion gene was confirmed by sequencing and was then cloned into pcDNA3.1(+) plasmid. The pcDNA3.1 (+)-MG7/PADRE was used to transfect an attenuated Salrmonella typhimuriurm.C57BL/6 mice were orally immunized with 1x108 cfu Salrmonella transfectants. Salmonella harboring the empty pcDNA3.1(+) plasmid and phosphate buffer saline (PBS)were used as negative controls. At the 6th week, serum titer of MG7-Ag specific antibody was detected by ELtSA.At the 8th week cellular immunity was detected by an unprimed proliferation test of the spleenocytes by using a [3H]-thymidine incorporation assay. Ehrlich ascites carcinoma cells expressing MG7-Ag were used as a model in tumor challenge assay to evaluate the protective effect of the vaccine.RESULTS: Serum titer of antibody against MG7-Ag was significantly higher in mice immunized with the vaccine than that in control groups (0.841 vs 0.347, P<0.01; 0.841 vs 0.298,P<0.01), while in vitro unprimed proliferation assay of the spleenocytes showed no statistical difference between those three groups. Two weeks after tumor challenge, 2 in 7 immunized mice were tumor free, while all the mice in the control groups showed tumor formation. CONCLUSION: Oral DNA vaccine against the MG7-Ag momitope of gastric cancer is immunogenic. It can induce significant humoral immunity against tumor in mice, and the vaccine has partially protective effects.

  3. Experimental Salmonella typhimurium infections in rats. I

    DEFF Research Database (Denmark)

    Hougen, H P; Jensen, E T; Klausen, B

    1989-01-01

    The course of experimentally induced Salmonella typhimurium infection was studied in three groups of inbred LEW rats: homozygous +/+, athymic rnu/rnu and isogeneic thymus-grafted rnu/rnu rats. In the first experiment the animals were inoculated intraperitoneally with 10(8) bacteria and all animal...

  4. Optimizing Salmonella enterica serovar Typhimurium for bacteria-mediated tumor therapy.

    Science.gov (United States)

    Felgner, Sebastian; Kocijancic, Dino; Frahm, Michael; Curtiss, Roy; Erhardt, Marc; Weiss, Siegfried

    2016-01-01

    Bacteria-mediated tumor therapy using Salmonella enterica serovar Typhimurium is a therapeutic option with great potential. Numerous studies explored the potential of Salmonella Typhimurium for therapeutic applications, however reconciling safety with vectorial efficacy remains a major issue. Recently we have described a conditionally attenuated Salmonella vector that is based on genetic lipopolysaccharide modification. This vector combines strong attenuation with appropriate anti-tumor properties by targeting various cancerous tissues in vivo. Therefore, it was promoted as an anti-tumor agent. In this addendum, we summarize these findings and demonstrate additional optimization steps that may further improve the therapeutic efficacy of our vector strain.

  5. The Research Progress of the Orally Attenuated Recombinant Salmonella Typhimurium Vector Vaccine%减毒沙门氏菌作为口服活疫苗载体的研究进展

    Institute of Scientific and Technical Information of China (English)

    马全英; 安芳兰; 刘萍; 祝秀梅; 吕志慧; 王凡; 刘学荣; 黄银君; 牟克斌

    2012-01-01

    文章就沙门氏菌相关基因的特点、减毒沙门氏菌载体激发的免疫应答、进入机体免疫系统的机制、减毒沙门氏菌的应用、载体疫苗的优越性及潜在危险性几方面综述了减毒沙门氏菌作为口服疫苗载体的研究进展,为新型菌苗的研制提供一种新的思路。%This article related genes from Salmonella characteristics of the related gene, attenuation salmonella carrier stimulate the immune re- sponse, into the mechanism of the immune system, the application of attenuated salmonella typhimurium, the superiority of vaccine vectors potentially dangerous areas and review of the attenuated salmonella as oral progress in a new type vaccine vectors for the development of novel vaccine provides a new way of thinking.

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

    Science.gov (United States)

    Rahman, Md Masudur; Uyangaa, Erdenebelig; Han, Young Woo; Hur, Jin; Park, Sang-Youel; Lee, John Hwa; Kim, Koanhoi; Eo, Seong Kug

    2015-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Rahman Md

    2012-07-01

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

  8. 40 CFR 798.5265 - The salmonella typhimurium reverse mutation assay.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 31 2010-07-01 2010-07-01 true The salmonella typhimurium reverse....5265 The salmonella typhimurium reverse mutation assay. (a) Purpose. The Salmonella typhimurium.... (1) A reverse mutation assay in Salmonella typhimurium detects mutation in a gene of a...

  9. Study of Salmonella Typhimurium Infection in Laying Hens.

    Science.gov (United States)

    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. Suppressors of Recb Mutations in Salmonella Typhimurium

    OpenAIRE

    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(+). W...

  11. Analysis of the contribution of bacteriophage ST64B to in vitro virulence traits of Salmonella enterica serovar Typhimurium

    DEFF Research Database (Denmark)

    Fresno, Ana Herrero; Leekitcharoenphon, Pimlapas; Hendriksen, Rene S.;

    2014-01-01

    Comparison of the publicly available genomes of the virulent Salmonella enterica serovar Typhimurium (S. Typhimurium) strains SL1344, 14028s and D23580 to that of the virulence-attenuated isolate LT2 revealed the absence of a full sequence of bacteriophage ST64B in the latter. Four selected ST64B...

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

    Science.gov (United States)

    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

  13. Study of Salmonella Typhimurium infection in laying hens

    Directory of Open Access Journals (Sweden)

    Kapil eChousalkar

    2016-02-01

    Full Text Available Members of Salmonella enterica are frequently involved in egg and egg product related human food poisoning outbreaks worldwide. In Australia, Salmonella Typhimurium is frequently involved in egg and egg product related foodborne illness and Salmonella Mbandaka has also been found to be a contaminant of the layer farm environment. The ability possessed by Salmonella Enteritidis to colonise reproductive organs and contaminate developing eggs has been well described. However, there are few studies investigating this ability for Salmonella Typhimurium. The hypothesis of this study was that the Salmonella Typhimurium can colonise the gut for a prolonged period of time and that horizontal infection through feces is the main route of egg contamination. At 14 weeks of age hens were orally infected with either S. Typhimurium PT 9 or S. Typhimurium PT 9 and Salmonella Mbandaka. Salmonella shedding in feces and eggs was monitored for 15 weeks post infection. Egg shell surface and internal contents of eggs laid 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% Typhimurium, 14.1% 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

  14. The engineered Salmonella typhimurium inhibits tumorigenesis in advanced glioma

    Directory of Open Access Journals (Sweden)

    Chen JQ

    2015-09-01

    Full Text Available Jian-qiang Chen,1 Yue-fu Zhan,2 Wei Wang,1 Sheng-nan Jiang,2,3 Xiang-ying Li21Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, People’s Republic of China; 2Department of Radiology, Affiliated to Haikou Hospital Xiangya School of Medicine, Central South University, Haikou, People’s Republic of China; 3Department of Nuclear Medicine, Central South University Xiangya School of Medicine Affiliated HaiKou Hospital, Haikou, Hainan, People’s Republic of ChinaObjective: 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

  15. Vaccination with Bivalent DNA Vaccine of α1-Giardin and CWP2 Delivered by Attenuated Salmonella typhimurium Reduces Trophozoites and Cysts in the Feces of Mice Infected with Giardia lamblia.

    Directory of Open Access Journals (Sweden)

    Xian-Min Feng

    Full Text Available Giardia lamblia is one of the most common infectious protozoans in human that may cause diarrhea in travelers. Searching for antigens that induced effectively protective immunity has become a key point in the development of vaccine against giardiasis.Mice vaccinated with G. lamblia trophozozite-specific α1-giardin DNA vaccine delivered orally by attenuated Salmonella typhimurium SL7027 elicited 74.2% trophozoite reduction, but only 28% reduction in cyst shedding compared with PBS buffer control. Oral vaccination with Salmonella-delivered cyst-specific CWP2 DNA produced 89% reduction in cysts shedding in feces of vaccinated mice. Significantly, the mice vaccinated with Salmonella-delivered bivalent α1-giardin and CWP2 DNA vaccines produced significant reduction in both trophozoite (79% and cyst (93% in feces of vaccinated mice. This parasite reduction is associated with the strong local mucosal IgA secretion and the IgG2a-dominant systemic immune responses in vaccinated mice.The results demonstrate that bivalent vaccines targeting α1-giardin and CWP2 can protect mice against the colonization of Giardia trophozoite and block the transformation of cyst in host at the same time, and can be used to prevent Giardia infection and block the transmission of giardiasis.

  16. The antimicrobial peptide cathelicidin-BF could be a potential therapeutic for Salmonella typhimurium infection.

    Science.gov (United States)

    Xia, Xi; Zhang, Lin; Wang, Yizhen

    2015-02-01

    Resistance is increasing to several critical antimicrobials used to treat Salmonella typhimurium infection, urging people to search for new antimicrobial agents. In this work, we reported the possibility of a potent antimicrobial peptide cathelicidin-BF found in the venom of the snake Bungarus fasciatus in treating Salmonella typhimurium infection. We tested its activity in biological fluids and in vivo using a mouse model of Salmonella typhimurium infection, and examined the effect of cathelicidin-BF on Salmonella invasion to epithelial cells. In addition, the biodistribution of cathelicidin-BF was evaluated by using in vivo optical imaging. The results revealed that cathelicidin-BF was unstable in gastrointestinal tract, but retained substantially active in murine serum. Cathelicidin-BF attenuated the clinical symptoms of Salmonella infected-mice, significantly reduced the number of internalized Salmonella and attenuated Salmonella-induced decreases in TER in epithelial cells. Our results provide a first indication for the potential of cathelicidin-BF as a novel therapeutic option for salmonellosis.

  17. Attenuated Salmonella Typhimurium lacking the pathogenicity island-2 type 3 secretion system grow to high bacterial numbers inside phagocytes in mice.

    Directory of Open Access Journals (Sweden)

    Andrew J Grant

    Full Text Available Intracellular replication within specialized vacuoles and cell-to-cell spread in the tissue are essential for the virulence of Salmonella enterica. By observing infection dynamics at the single-cell level in vivo, we have discovered that the Salmonella pathogenicity island 2 (SPI-2 type 3 secretory system (T3SS is dispensable for growth to high intracellular densities. This challenges the concept that intracellular replication absolutely requires proteins delivered by SPI-2 T3SS, which has been derived largely by inference from in vitro cell experiments and from unrefined measurement of net growth in mouse organs. Furthermore, we infer from our data that the SPI-2 T3SS mediates exit from infected cells, with consequent formation of new infection foci resulting in bacterial spread in the tissues. This suggests a new role for SPI-2 in vivo as a mediator of bacterial spread in the body. In addition, we demonstrate that very similar net growth rates of attenuated salmonellae in organs can be derived from very different underlying intracellular growth dynamics.

  18. Genetic Manipulation of Pathogenicity Loci in Non-Typhimurium Salmonella

    Science.gov (United States)

    Butela, Kristen; Lawrence, Jeffrey G.

    2012-01-01

    The traditional genetic tools used in Salmonella enterica serovar Typhimurium rely heavily on a high-transducing mutant of bacteriophage P22. P22 recognizes its hosts by the structure of their O-antigens, which vary among serovars of Salmonella; therefore, it cannot be used in most non-Typhimurium Salmonella, including the majority of those causing food-borne illnesses in both humans and livestock. Bacteriophage P1 infects a variety of enteric bacteria, including galE mutants of serovar Typhimurium; however, the degree to which the presence of coimmune prophages, the lack of required attachment sites or the lack of host factors act as barriers to using phage P1 in natural isolates of Salmonella is unknown. Here, we show that recombineering can be used to make virtually any serovar of Salmonella susceptible to P1 infection; as a result, P1 can be utilized for facile genetic manipulation of non-Typhimurium Salmonella, including movement of very large pathogenicity islands. A toolkit for easy manipulation of non-Typhimurium serovars of Salmonella is described. PMID:23041268

  19. Salmonella typhimurium Invasion Induces Apoptosis in Infected Macrophages

    Science.gov (United States)

    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.

  20. Histologic, cytologic, and bacteriologic examinations of experimentally induced Salmonella typhimurium infection in Lewis rats

    DEFF Research Database (Denmark)

    Thygesen, P; Martinsen, C; Hougen, H P;

    2000-01-01

    Histopathologic changes, cellular composition, and bacterial spreading were studied in rat spleen after experimentally induced infection with Salmonella typhimurium.......Histopathologic changes, cellular composition, and bacterial spreading were studied in rat spleen after experimentally induced infection with Salmonella typhimurium....

  1. Construction and expression of attenuated salmonella typhimurium carrying human adiponectin gene eukaryotic expression vector%重组人脂联素基因在减毒沙门氏菌中的表达

    Institute of Scientific and Technical Information of China (English)

    周静; 周洲; 吴莹; 向廷秀; 姜政; 王丕龙

    2009-01-01

    目的:构建携带人脂联素(AdipoQ)基因真核表达载体并在减毒沙门氏菌中表达,为AdipoQ对非酒精性脂肪性肝病(NAFLD)的基因治疗提供依据.方法:从人脂肪组织中提取总RNA,通过实时荧光定量PCR(rRT-PCR)方法获得Adi-poQ基因并将其克隆到真核表达载体pEGFP-NI上,构建pEG-FP-N1-AdipoQ重组载体.重组质粒经鉴定后再电转入减毒沙门氏菌SL7207中表达.结果:克隆的人AdipoQ基因744 bp测序结果显示:1个碱基发生突变,654位:A→T,突变率为0.1%,氨基酸Glu→Asp.经SDS-PAGE,Western Blot检测融合蛋白Mr约为55×10~3(绿色荧光蛋白Mr约为27×10~3),能够被AdipoQ抗体识别.结论:成功构建携带AdipoQ基因真核表达载体的减毒沙门氏菌株,AdipoQ基因能够在减毒沙门氏菌中表达并与绿色荧光蛋白融合.为进一步研究其在NAFLD中的作用机制奠定了基础.%AIM: To construct and express an attenuated Salmonella typhimurium strain contraining human adiponectin gene eukaryotic expression vector, in order to lay the foundation for the genetic therapy of nonalcoholic fatty liver disease in future. METHODS: Total mRNA was extracted from human fat tissue and the adiponectin cDNA was obtained by RT-PCR, and then cloned into eukaryotic expression vector pEGFP-N1. The recombinant vector was identified, and transformed into attenuated Salmonella typhimurium strain SL7207, and the recombinant strain SL7207/pEGFP-NI-AdipoQ was screened by green fluorescent microscope and Western Blot. RESULTS: Enzyme digestion analysis and sequencing showed that the target genes was found to be 744 bp, and had been inserted into eukaryotic expression vector, but as compared with gene reported by GenBank, 0. 1% of the gene mutation and O. 4% of amino acid residues change, respectively: 654 bp: A→T, amino acids: Glu→Asp. SDS-PAGE demonstrated that pEGFP-N1-AdipoQ was expressed in SL7207 strain, and the relatived molecular mass of the GFP-AdipoQ fusion protein

  2. Isolation and Evaluation Virulence Factors of Salmonella typhimurium and Salmonella enteritidis in Milk and Dairy Products

    Directory of Open Access Journals (Sweden)

    Shima Shaigan nia

    2014-06-01

    Conclusions: To our best knowledge the present study is the first prevalence report of Salmonella spp., Salmonella enteritidis and Salmonella typhimurium in raw sheep and goat samples in Iran. Consumption of pasteurized milk and dairy products can reduce the risk of salmonellosis.

  3. Identification of new secreted effectors in Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Geddes, Kaoru; Worley, Micah; Niemann, George; Heffron, Fred

    2005-10-01

    A common theme in bacterial pathogenesis is the secretion of bacterial products that modify cellular functions to overcome host defenses. Gram-negative bacterial pathogens use type III secretion systems (TTSSs) to inject effector proteins into host cells. The genes encoding the structural components of the type III secretion apparatus are conserved among bacterial species and can be identified by sequence homology. In contrast, the sequences of secreted effector proteins are less conserved and are therefore difficult to identify. A strategy was developed to identify virulence factors secreted by Salmonella enterica serovar Typhimurium into the host cell cytoplasm. We constructed a transposon, which we refer to as mini-Tn5-cycler, to generate translational fusions between Salmonella chromosomal genes and a fragment of the calmodulin-dependent adenylate cyclase gene derived from Bordetella pertussis (cyaA'). In-frame fusions to bacterial proteins that are secreted into the eukaryotic cell cytoplasm were identified by high levels of cyclic AMP in infected cells. The assay was sufficiently sensitive that a single secreted fusion could be identified among several hundred that were not secreted. This approach identified three new effectors as well as seven that have been previously characterized. A deletion of one of the new effectors, steA (Salmonella translocated effector A), attenuated virulence. In addition, SteA localizes to the trans-Golgi network in both transfected and infected cells. This approach has identified new secreted effector proteins in Salmonella and will likely be useful for other organisms, even those in which genetic manipulation is more difficult.

  4. Salmonella typhimurium peptidase active on carnosine.

    Science.gov (United States)

    Kirsh, M; Dembinski, D R; Hartman, P E; Miller, C G

    1978-01-01

    Wild-type Salmonella typhimurium can use carnosine (beta-alanyl-L-histidine) as a source of histidine, but carnosine utilization is blocked in particular mutants defective in the constitutive enzyme peptidase D, the product of the pepD gene. Biochemical evidence for assigning carnosinase activity to peptidase D (a broad-specificity dipeptidase) includes: (i) coelution of carnosinase and dipeptidase activity from diethylaminoethyl-cellulose and Bio-Gel P-300 columns; (ii) coelectrophoresis of carnosinase and dipeptidase on polyacrylamide gels; and (iii) inactivation of carnosinase and dipeptidase activities at identical rates at both 4 and 42 degrees C. Genetic evidence indicates that mutations leading to loss of carnosinase activity map at pepD. Several independent pepD mutants have been isolated by different selection procedures, and the patterns of peptide utilization of strains carrying various pepD alleles have been studied. Many pepD mutations lead to the production of partially active peptidase D enzymes with substrate specificities that differ strikingly from those of the wild-type enzyme. The growth yields of carnosinase-deficient strains growing in Difco nutrient broth indicate that carnosine is the major utilizable source of histidine in this medium. PMID:26655

  5. Induction of protective immunity against Streptococcus mutans colonization after mucosal immunization with attenuated Salmonella enterica serovar typhimurium expressing an S. mutans adhesin under the control of in vivo-inducible nirB promoter.

    Science.gov (United States)

    Huang, Y; Hajishengallis, G; Michalek, S M

    2001-04-01

    The purpose of the present study was to evaluate the effectiveness of an attenuated Salmonella enterica serovar Typhimurium vaccine strain expressing the saliva-binding region (SBR) of the Streptococcus mutans antigen I/II adhesin, either alone or linked with the mucosal adjuvant cholera toxin A2 and B subunits (CTA2/B) and under the control of the anaerobically inducible nirB promoter, in inducing a protective immune response against S. mutans infection. BALB/c mice were immunized by either the intranasal or the intragastric route with a single dose of 10(9) or 10(10) Salmonella CFU, respectively. The Salmonella vaccine strain expressing an unrelated antigen (fragment C of tetanus toxin [TetC]) was also used for immunization as a control. Samples of serum and secretion (saliva and vaginal washes) were collected prior to and following immunization and assessed for antibody activity by enzyme-linked immunosorbent assay. Anti-SBR antibodies were detected in the serum and saliva of experimental animals by week 3 after immunization. A booster immunization at week 17 after the initial immunization resulted in enhanced immune responses to the SBR. The serum immunoglobulin G subclass profiles were indicative of T helper type 1 responses against both the vector and the SBR antigen. To determine the effectiveness of these responses on the protection against S. mutans infection, mice were challenged after the second immunization with a virulent strain of S. mutans which was resistant to tetracycline and erythromycin. Prior to the challenge, mice were treated for 5 days with tetracycline, erythromycin, and penicillin. S. mutans was initially recovered from all of the challenged mice. This bacterium persisted at high levels for at least 5 weeks in control TetC-immunized or nonimmunized mice despite the reappearance of indigenous oral organisms. However, mice immunized with Salmonella clones expressing SBR or SBR-CTA2/B demonstrated a significant reduction in the number of S

  6. Subversion of innate and adaptive immune activation induced by structurally modified lipopolysaccharide from Salmonella typhimurium.

    Science.gov (United States)

    Pastelin-Palacios, Rodolfo; Gil-Cruz, Cristina; Pérez-Shibayama, Christian I; Moreno-Eutimio, Mario A; Cervantes-Barragán, Luisa; Arriaga-Pizano, Lourdes; Ludewig, Burkhard; Cunningham, Adam F; García-Zepeda, Eduardo A; Becker, Ingeborg; Alpuche-Aranda, Celia; Bonifaz, Laura; Gunn, John S; Isibasi, Armando; López-Macías, Constantino

    2011-08-01

    Salmonella are successful pathogens that infect millions of people every year. During infection, Salmonella typhimurium changes the structure of its lipopolysaccharide (LPS) in response to the host environment, rendering bacteria resistant to cationic peptide lysis in vitro. However, the role of these structural changes in LPS as in vivo virulence factors and their effects on immune responses and the generation of immunity are largely unknown. We report that modified LPS are less efficient than wild-type LPS at inducing pro-inflammatory responses. The impact of this LPS-mediated subversion of innate immune responses was demonstrated by increased mortality in mice infected with a non-lethal dose of an attenuated S. typhimurium strain mixed with the modified LPS moieties. Up-regulation of co-stimulatory molecules on antigen-presenting cells and CD4(+) T-cell activation were affected by these modified LPS. Strains of S. typhimurium carrying structurally modified LPS are markedly less efficient at inducing specific antibody responses. Immunization with modified LPS moiety preparations combined with experimental antigens, induced an impaired Toll-like receptor 4-mediated adjuvant effect. Strains of S. typhimurium carrying structurally modified LPS are markedly less efficient at inducing immunity against challenge with virulent S. typhimurium. Hence, changes in S. typhimurium LPS structure impact not only on innate immune responses but also on both humoral and cellular adaptive immune responses.

  7. Subversion of innate and adaptive immune activation induced by structurally modified lipopolysaccharide from Salmonella typhimurium

    Science.gov (United States)

    Pastelin-Palacios, Rodolfo; Gil-Cruz, Cristina; Pérez-Shibayama, Christian I; Moreno-Eutimio, Mario A; Cervantes-Barragán, Luisa; Arriaga-Pizano, Lourdes; Ludewig, Burkhard; Cunningham, Adam F; García-Zepeda, Eduardo A; Becker, Ingeborg; Alpuche-Aranda, Celia; Bonifaz, Laura; Gunn, John S; Isibasi, Armando; López-Macías, Constantino

    2011-01-01

    Salmonella are successful pathogens that infect millions of people every year. During infection, Salmonella typhimurium changes the structure of its lipopolysaccharide (LPS) in response to the host environment, rendering bacteria resistant to cationic peptide lysis in vitro. However, the role of these structural changes in LPS as in vivo virulence factors and their effects on immune responses and the generation of immunity are largely unknown. We report that modified LPS are less efficient than wild-type LPS at inducing pro-inflammatory responses. The impact of this LPS-mediated subversion of innate immune responses was demonstrated by increased mortality in mice infected with a non-lethal dose of an attenuated S. typhimurium strain mixed with the modified LPS moieties. Up-regulation of co-stimulatory molecules on antigen-presenting cells and CD4+ T-cell activation were affected by these modified LPS. Strains of S. typhimurium carrying structurally modified LPS are markedly less efficient at inducing specific antibody responses. Immunization with modified LPS moiety preparations combined with experimental antigens, induced an impaired Toll-like receptor 4-mediated adjuvant effect. Strains of S. typhimurium carrying structurally modified LPS are markedly less efficient at inducing immunity against challenge with virulent S. typhimurium. Hence, changes in S. typhimurium LPS structure impact not only on innate immune responses but also on both humoral and cellular adaptive immune responses. PMID:21631497

  8. Salmonella enterica serovar Typhimurium exploits inflammation to modify swine intestinal microbiota.

    Directory of Open Access Journals (Sweden)

    Rosanna eDrumo

    2016-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  10. Polyamines Are Required for Virulence in Salmonella enterica Serovar Typhimurium

    DEFF Research Database (Denmark)

    Jelsbak, Lotte; Thomsen, Line Elnif; Wallrodt, Inke;

    2012-01-01

    Sensing and responding to environmental cues is a fundamental characteristic of bacterial physiology and virulence. Here we identify polyamines as novel environmental signals essential for virulence of Salmonella enterica serovar Typhimurium, a major intracellular pathogen and a model organism......, we show that an S. Typhimurium polyamine mutant is defective for invasion, intracellular survival, killing of the nematode Caenorhabditis elegans and systemic infection of the mouse model of typhoid fever. Virulence of the mutant could be restored by genetic complementation, and invasion...

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

    Science.gov (United States)

    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.

  12. Amperometric biosensor for Salmonella typhimurium detection in milk

    Science.gov (United States)

    This paper reports an amperometric biosensor for rapid and sensitive Salmonella Typhimurium detection in milk. The biosensor was assembled from the self-assembled monolayers technique on a gold surface. In this device, polyclonal antibodies were oriented by protein A. The biosensor structure was cha...

  13. Large outbreaks of Salmonella Typhimurium infection in Denmark in 2008

    DEFF Research Database (Denmark)

    Ethelberg, S.; Wingstrand, Anne; Jensen, T.

    2008-01-01

    An outbreak of Salmonella Typhimurium phage type U292 has been ongoing in Denmark since 1 April, with 1,054 cases registered until 23 October 2008. Extensive investigations including hypothesis-generating interviews, matched case-control studies, cohort studies in embedded outbreaks, shopping list...

  14. Molecular Characterization of Salmonella Typhimurium Highly Successful Outbreak Strains

    DEFF Research Database (Denmark)

    Petersen, Randi Føns; Litrup, Eva; Larsson, Jonas T.;

    2011-01-01

    Three large clusters of Salmonella Typhimurium infections in Denmark in 2008 and 2009 were defined by multilocus variable number of tandem repeat analysis (MLVA). One of these proved to be the hereto largest Danish cluster of salmonellosis with 1446 cases. Two smaller clusters with a total of 197...

  15. Karakterisering van de zuurgevoeligheid van Salmonella typhimurium faagtype DT104

    NARCIS (Netherlands)

    de Jonge R; van Leusden FM; Dufrenne JB; Ritmeester WS; Delfgou-van Asch EHM; van Pelt W; LBG

    1999-01-01

    Het aantal gevallen van salmonellosis in Nederland veroorzaakt door Salmonella typhimurium faagtype DT104 is toegenomen van 10 in 1985 tot 163 in 1997 (10% van alle gevallen van salmonellosis). De stam lijkt zijn oorsprong te hebben in het Verenigd Koninkrijk. Daar wordt inmiddels 20% van alle gev

  16. Micro amperometric immunosensor for the detection of salmonella typhimurium

    Science.gov (United States)

    Sun, Jizhou; Xia, Shanhong; Bian, Chao; Qu, Lan

    2008-12-01

    In this paper, a micro amperometric immunosensor based on Micro-Electro-Mechanical Systems technology for the detection of Salmonella typhimurium (S. typhimurium) was constructed by immobilizing a polyclonal antibody (the bio-molecular recognition element) onto the surface of polypyrrole(PPy) /staphylococcal protein A(SPA) modified Pt electrode. Pyrrole doped with SPA was co-electropolymerized onto the working electrode surface by cyclic voltammetry in 10 minutes for orientation-controlled immobilization of salmonella capture antibodies. S. typhimurium with the concentration of 102cfu/ml could be detected by this immunosensor with a controllable and convenient manipulation to effectively modify the sensing surface more rapidly with less consumption of reagent (10µL), which showed the good property of the sensor. It is potential to develop a micro biosensor that can be used for convenient, accurate, cost-effective and real-time sensing of pathogens in food products.

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

    Science.gov (United States)

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

  18. Deletion of Salmonella enterica serovar typhimurium sipC gene

    Institute of Scientific and Technical Information of China (English)

    Maryam; Safarpour; Dehkordi; Abbas; Doosti; Asghar; Arshi

    2015-01-01

    Objective:To construct a novel plasmid as Salmonella enterica serovar typhimurium(S.typhimurium)sip C gene knockouts candidate.Methods:In this research,50upstream and 30downstream regions of S.typhimurium sip C gene and kanamycin gene were PCR amplified.Each of these DNA fragment was cloned into p GEM T-easy vector.The construct was confirmed by PCR and restriction digest.Results:PCR amplified 320,206 and 835 bp DNA fragments were subcloned into p ET-32 vector resulting with a plasmid called p ET-32-sip C up-kan-sip C down.Conclusions:The new plasmid(p ET-32-sip C up-kan-sip C down)is useful for genetic engineering and for future manipulation of S.typhimurium sip C gene.

  19. Deletion of Salmonella enterica serovar typhimurium sipC gene

    Institute of Scientific and Technical Information of China (English)

    Maryam Safarpour Dehkordi; Abbas Doosti; Asghar Arshi

    2015-01-01

    Objective: To construct a novel plasmid as Salmonella enterica serovar typhimurium (S. typhimurium) sipC gene knockouts candidate. Methods: In this research, 50 upstream and 30 downstream regions of S. typhimurium sipC gene and kanamycin gene were PCR amplified. Each of these DNA fragment was cloned into pGEM T-easy vector. The construct was confirmed by PCR and restriction digest. Results: PCR amplified 320, 206 and 835 bp DNA fragments were subcloned into pET-32 vector resulting with a plasmid called pET-32-sipC up-kan-sip C down. Conclusions: The new plasmid (pET-32-sipC up-kan-sip C down) is useful for genetic engineering and for future manipulation of S. typhimurium sipC gene.

  20. Global gene expression of a murein (Braun) lipoprotein mutant of Salmonella enterica serovar Typhimurium by microarray analysis.

    Science.gov (United States)

    Fadl, A A; Galindo, C L; Sha, J; Klimpel, G R; Popov, V L; Chopra, A K

    2006-06-01

    Braun/murein lipoprotein (Lpp) is one of the major outer membrane components of gram-negative enteric bacteria involved in inflammatory responses and septic shock. In previous studies, we reported that two copies of the lipoprotein (lpp) gene (designated as lppA and lppB) existed on the chromosome of Salmonella enterica serovar Typhimurium. Deletion of both lppA and lppB genes rendered Salmonella defective in invasion, motility, induction of cytotoxicity, and production of inflammatory cytokines/chemokines. The lppAB double-knockout (DKO) mutant was attenuated in mice, and animals immunized with this mutant were protected against subsequent challenge with lethal doses of wild-type (wt) S. Typhimurium. To better understand how deletion of the lpp gene might affect Salmonella virulence, we performed global transcriptional profiling of the genes in the wt and the lppAB DKO mutant of S. Typhimurium using microarrays. Our data revealed alterations in the expression of flagellar genes, invasion-associated type III secretion system genes, and transcriptional virulence gene regulators in the lppAB DKO mutant compared to wt S. Typhimurium. These data correlated with the lppAB DKO mutant phenotype and provided possible mechanism(s) of Lpp-associated attenuation in S. Typhimurium. Although these studies were performed in in vitro grown bacteria, our future research will be targeted at global transcriptional profiling of the genes in in vivo grown wt S. Typhimurium and its Lpp mutant.

  1. Isolation of Salmonella typhimurium from outbreak-associated cake mix.

    Science.gov (United States)

    Zhang, Guodong; Ma, Li; Patel, Nehal; Swaminathan, Bala; Wedel, Stephanie; Doyle, Michael P

    2007-04-01

    During May and June of 2005, 26 persons in several states were infected by a single strain (isolates indistinguishable by pulsed-field gel electrophoresis) of Salmonella enterica serotype Typhimurium after eating cake batter ice cream. The cake mix used to prepare the cake batter in the ice cream was implicated by epidemiologic investigation as the source of Salmonella contamination. Initial tests did not detect Salmonella in cake mix collected during the outbreak investigation. The objective of this study was to evaluate different procedures to isolate Salmonella from the implicated cake mix, cake, and ice cream. All outbreak-associated food samples (14 samples) were collected during the outbreak investigation by health departments of several of the states involved. Different combinations of Salmonella isolation procedures, including sample size, preenrichment broth, enrichment broth, enrichment temperature, and isolation medium, were used. Salmonella Typhimurium was isolated from two cake mix samples; the food isolates were indistinguishable from the outbreak pattern by pulsed-field gel electrophoresis subtyping. Universal preenrichment broth was substantially better than was lactose broth for preenrichment, and tetrathionate broth was better than was Rappaport-Vassiliadis broth for isolating Salmonella from the two positive cake mix samples. Although more typical Salmonella colonies were observed on plates from enrichment cultures grown at 35 degrees C, more confirmed Salmonella isolates were obtained from plates of enrichment cultures grown at 42 degrees C. Brilliant green agar, xylose lysine tergitol 4 agar, xylose lysine desoxycholate agar, Hektoen enteric agar, and bismuth sulfite agar plates were equally effective in isolating Salmonella from cake mix. The best combination of preenrichment-enrichment conditions for isolating the outbreak strain of Salmonella was preenrichment of cake mix samples in universal preenrichment broth at 35 degrees C for 24 h

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

    Directory of Open Access Journals (Sweden)

    Uday Shankar Allam

    Full Text Available 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.

  3. Identification of Metabolic Pathways Essential for Fitness of Salmonella Typhimurium In Vivo

    DEFF Research Database (Denmark)

    Jelsbak, Lotte; Hartman, Hassan; Schroll, Casper

    2014-01-01

    Bacterial infections remain a threat to human and animal health worldwide, and there is an urgent need to find novel targets for intervention. In the current study we used a computer model of the metabolic network of Salmonella enterica serovar Typhimurium and identified pairs of reactions (cut...... in vitro but was attenuated during infection showing that polyamines are essential for virulence apparently in a growth independent manner. The serA/glyA cut-set was found to be growth attenuated as predicted by the model. However, not only the double mutant, but also the glyA mutant, were found...

  4. Inhibitory Effects of Several Essential Oils towards Salmonella typhimurium, Salmonella paratyphi A and Salmonella paratyphi B

    Directory of Open Access Journals (Sweden)

    S.F. Mazhar

    2014-09-01

    Full Text Available Plant essential oils are natural products extracted from plants and because of their antimicrobial properties can be used as natural additives in foods. They are also useful for decontamination of food-borne pathogens and can be a safe additive in foods. The antimicrobial activities of essential oils belonging to Saturiea hortensis, Thymus vulgaris, Mentha polegium, Cuminum cyminum, Lavandula officinalis and Mentha viridis L. (spearmint were investigated at different concentrations (0.1, 0.3, 0.5, 1, 2, 5 and 10%v/v against Salmonella typhimurium, Salmonella paratyphi A and Salmonella paratyphi B by using the agar well diffusion method. Essential oils showed inhibitory effect on Salmonella spp. in the agar well diffusion assay. In addition, the capability of essential oils for decontamination of minced row beef, ground beef, minced raw chicken and minced raw fish inoculated with Salmonella spp. at 0.1 and 0.5%v/v were assessed. Reduction of the Salmonella spp. population was observed following the inoculation of the cultures with 0.1 and 0.5%v/v essential oils.

  5. Ingress of Salmonella enterica Typhimurium into tomato leaves through hydathodes.

    Directory of Open Access Journals (Sweden)

    Ganyu Gu

    Full Text Available Internal contamination of Salmonella in plants is attracting increasing attention for food safety reasons. In this study, three different tomato cultivars "Florida Lanai", "Crown Jewel", "Ailsa Craig" and the transgenic line Sp5 of "Ailsa Craig" were inoculated with 1 µl GFP-labeled Salmonella Typhimurium through guttation droplets at concentrations of 10(9 or 10(7 CFU/ml. Survival of Salmonella on/in tomato leaves was detected by both direct plating and enrichment methods. Salmonella cells survived best on/in the inoculated leaves of cultivar "Ailsa Craig" and decreased fastest on/in "Florida Lanai" leaves. Increased guttation in the abscisic acid over-expressing Sp5 plants may have facilitated the entrance of Salmonella into leaves and the colonization on the surface of tomato leaves. Internalization of Salmonella Typhimurium in tomato leaves through guttation drop inoculation was confirmed by confocal laser microscopy. For the first time, convincing evidence is presented that S. enterica can enter tomato leaves through hydathodes and move into the vascular system, which may result in the internal translocation of the bacteria inside plants.

  6. Polyamines Are Required for Virulence in Salmonella enterica Serovar Typhimurium

    DEFF Research Database (Denmark)

    Jelsbak, Lotte; Thomsen, Line Elnif; Wallrodt, Inke;

    2012-01-01

    for studying typhoid fever. Central to its virulence are two major virulence loci Salmonella Pathogenicity Island 1 and 2 (SPI1 and SPI2). SPI1 promotes invasion of epithelial cells, whereas SPI2 enables S. Typhimurium to survive and proliferate within specialized compartments inside host cells. In this study......, we show that an S. Typhimurium polyamine mutant is defective for invasion, intracellular survival, killing of the nematode Caenorhabditis elegans and systemic infection of the mouse model of typhoid fever. Virulence of the mutant could be restored by genetic complementation, and invasion...

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

    Science.gov (United States)

    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.

  8. Attenuated Salmonella typhimurium as a carrier for prokaryotic and eukaryotic expression vectors%减毒沙门氏菌作为原核表达宿主菌和真核表达载体的研究

    Institute of Scientific and Technical Information of China (English)

    迪卡; 陈雪燕; 帅江冰; 陈宁; 方维焕

    2006-01-01

    An attenuated Salmonella enterica serovar typhimurium strain as the host for recombinant prokaryotic and eukaryotic vectors containing the enhanced green fluorescent protein (eGFP) gene was examined by fluorimetric and fluorescent microscopic methods. Expression of eGFP was dependent on the concentration of IPTG used for induction, being optimal at 0.5 mmol. L-1 . Further increase to 0.75mmol. L-1 did not increase the fluorescence output. This dose-dependent induction was not apparent when E. coli was used as the host strain. The expression was higher in S. typhimurium than in E. coli typhimurium strain was invasive, though less than its parent strain, into the HeLa cells and able to deliver the recombinant eukaryotic plasmid pcDNA3-eGFP for expression of eGFP as shown by fluorescing cells 48 h after transfection. The results of this experiment also demonstrate the utility of direct measurement of fluorescence and optical density in a multifunctional microplate-based spectrophotometric reader, allowing high throughput multiple quantitative comparisons of eGFP expression by different host strains or the same strain under different conditions or even different expression vectors.%本研究以增强型绿色荧光蛋白(eGFP)为报告基因,探讨了减毒沙门氏菌作为原核表达宿主菌和真核表达载体的可行性.通过多功能分光光度仪测定细菌的OD600和eGFP在大肠杆菌和减毒沙门氏菌中的表达量,结果表明:eGFP在沙门氏菌中的表达量依赖于IPTG的浓度,最佳浓度为0.5 mmol·L-1,增加浓度至0.75 mmol·L-1不能增加eGFP的表达量;而该现象在大肠杆菌中不明显.当IPTG浓度等于或大于0.5 mmol·L-1时,沙门氏菌中eGFP的表达量显著高于大肠杆菌.若以相对荧光度(1个OD600单位的荧光值,即eGFP相对表达量)表示,两种宿主菌的最佳诱导时间均为3 h.Hela细胞侵袭力试验表明该减毒沙门氏菌仍具有侵袭力,同时以脂质体转染为对

  9. Internal promoters of the his operon in Salmonella typhimurium.

    OpenAIRE

    Schmid, M. B.; Roth, J. R.

    1983-01-01

    Two internal promoters in the his operon of Salmonella typhimurium have been precisely mapped genetically. The internal promoters are found in, or very close to, gene border regions in the his operon. The his operon was examined for the presence of additional internal promoters whose transcripts were sensitive to rho-mediated transcription termination and therefore had escaped detection. No new internal promoters were found. It is argued that the internal promoters described here are not like...

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

    Directory of Open Access Journals (Sweden)

    Barbara eChirullo

    2015-09-01

    Full Text Available 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 the STM14028-intracellular colonization. Moreover, LPS in vivo treatment induces increased cytokines blood level and body temperature at 4 hours 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.

  11. Salmonella Typhimurium and Multidirectional Communication in the Gut

    Science.gov (United States)

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

    2016-01-01

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

  12. Persistence of salmonella Typhimurium in Nopal

    Science.gov (United States)

    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...

  13. Persistence of salmonella typhimurium in nopal cladodes

    Science.gov (United States)

    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...

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

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    Maria Braukmann

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  16. Attenuation of 10 MeV electron beam energy to achieve low doses does not affect Salmonella spp. inactivation kinetics

    Science.gov (United States)

    Hieke, Anne-Sophie Charlotte; Pillai, Suresh D.

    2015-05-01

    The effect of attenuating the energy of a 10 MeV electron beam on Salmonella inactivation kinetics was investigated. No statistically significant differences were observed between the D10 values of either Salmonella 4,[5],12:i:- or a Salmonella cocktail (S. 4,[5],12:i:-, Salmonella Heidelberg, Salmonella Newport, Salmonella Typhimurium, Salmonella) when irradiated with either a non-attenuated 10 MeV eBeam or an attenuated 10 MeV eBeam (~2.9±0.22 MeV). The results show that attenuating the energy of a 10 MeV eBeam to achieve low doses does not affect the inactivation kinetics of Salmonella spp. when compared to direct 10 MeV eBeam irradiation.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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...

  19. The Base Excision Repair system of Salmonella enterica serovar typhimurium counteracts DNA damage by host nitric oxide.

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    Anthony R Richardson

    2009-05-01

    Full Text Available Intracellular pathogens must withstand nitric oxide (NO. generated by host phagocytes. Salmonella enterica serovar Typhimurium interferes with intracellular trafficking of inducible nitric oxide synthase (iNOS and possesses multiple systems to detoxify NO.. Consequently, the level of NO. stress encountered by S. Typhimurium during infection in vivo has been unknown. The Base Excision Repair (BER system recognizes and repairs damaged DNA bases including cytosine and guanine residues modified by reactive nitrogen species. Apurinic/apyrimidinic (AP sites generated by BER glycosylases require subsequent processing by AP endonucleases. S. Typhimurium xth nfo mutants lacking AP endonuclease activity exhibit increased NO. sensitivity resulting from chromosomal fragmentation at unprocessed AP sites. BER mutant strains were thus used to probe the nature and extent of nitrosative damage sustained by intracellular bacteria during infection. Here we show that an xth nfo S. Typhimurium mutant is attenuated for virulence in C3H/HeN mice, and virulence can be completely restored by the iNOS inhibitor L-NIL. Inactivation of the ung or fpg glycosylase genes partially restores virulence to xth nfo mutant S. Typhimurium, demonstrating that NO. fluxes in vivo are sufficient to modify cytosine and guanine bases, respectively. Mutants lacking ung or fpg exhibit NO.-dependent hypermutability during infection, underscoring the importance of BER in protecting Salmonella from the genotoxic effects of host NO.. These observations demonstrate that host-derived NO. damages Salmonella DNA in vivo, and the BER system is required to maintain bacterial genomic integrity.

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

    Science.gov (United States)

    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.

  1. Marcadores epidemiológicos de Salmonella typhimurium e Salmonella agona Epidemiological markers of Salmonella typhimurium and Salmonella agona

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    Sueli Aparecida Fernandes

    1992-04-01

    Full Text Available Entre as cepas de S. typhimurium e S. agona isoladas no período 1971-1987 foram caracterizados os biotipos, colicinotipos e antibiotipos de 734 cepas de S. typhimurium e 631 de S. agona. As 734 cepas de S. typhimurium foram classificadas em 65 biotipos com o predomínio dos biotipos 1a com 28,34%, 1b com 29,84% e 9bi com 18,25%. Com relação a S. agona, o biotipo 1a com 87,16% representou entre nós o clone amplamente disseminado. Foram encontradas freqüências baixas de cepas colicinogênicas, entretanto, a colicinotipia parece ser um bom método quando aplicada ao estudo de amostras homogêneas provenientes de surtos. Acentuada multirresistência aos agentes antimicrobianos, foi observada principalmente entre aquelas cepas de origem humana quase sempre representadas por cepas hospitalaresAmong S. typhimurium and S. agona strains isolated during the period from 1971 to 1987, the biotypes, colicine types and resistance patterns were determined for 734 S. typhimurium and 631 S. agona strains. Among 734 S. typhimurium strains 65 biotypes were disclosed with prevalence of biotypes 1a (28,34%, 1b (29,84% and 9bi (18,28. Concerning S. agona, the biotype 1a represented by 87,16%, was the commonest clone among our strains. Although colicine typing added little information to characterize these serotypes, it should be usefull when applied in epidemilogical study of outbreaks. It was observed multiply antimicrobial resistance mainly among human strains, particularly from nosocomial origins.

  2. The ferric enterobactin transporter Fep is required for persistent Salmonella enterica serovar typhimurium infection.

    Science.gov (United States)

    Nagy, Toni A; Moreland, Sarah M; Andrews-Polymenis, Helene; Detweiler, Corrella S

    2013-11-01

    Most bacterial pathogens require iron to grow and colonize host tissues. The Gram-negative bacterium Salmonella enterica serovar Typhimurium causes a natural systemic infection of mice that models acute and chronic human typhoid fever. S. Typhimurium resides in tissues within cells of the monocyte lineage, which limit pathogen access to iron, a mechanism of nutritional immunity. The primary ferric iron import system encoded by Salmonella is the siderophore ABC transporter FepBDGC. The Fep system has a known role in acute infection, but it is unclear whether ferric iron uptake or the ferric iron binding siderophores enterobactin and salmochelin are required for persistent infection. We defined the role of the Fep iron transporter and siderophores in the replication of Salmonella in macrophages and in mice that develop acute followed by persistent infections. Replication of wild-type and iron transporter mutant Salmonella strains was quantified in cultured macrophages, fecal pellets, and host tissues in mixed- and single-infection experiments. We show that deletion of fepB attenuated Salmonella replication and colonization within macrophages and mice. Additionally, the genes required to produce and transport enterobactin and salmochelin across the outer membrane receptors, fepA and iroN, are needed for colonization of all tissues examined. However, salmochelin appears to be more important than enterobactin in the colonization of the spleen and liver, both sites of dissemination. Thus, the FepBDGC ferric iron transporter and the siderophores enterobactin and salmochelin are required by Salmonella to evade nutritional immunity in macrophages and cause persistent infection in mice.

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

    Science.gov (United States)

    Santos, António J M; Durkin, Charlotte H; Helaine, Sophie; Boucrot, Emmanuel; Holden, David W

    2016-07-01

    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.

  4. Live attenuated S. Typhimurium vaccine with improved safety in immuno-compromised mice.

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    Balamurugan Periaswamy

    Full Text Available Live attenuated vaccines are of great value for preventing infectious diseases. They represent a delicate compromise between sufficient colonization-mediated adaptive immunity and minimizing the risk for infection by the vaccine strain itself. Immune defects can predispose to vaccine strain infections. It has remained unclear whether vaccine safety could be improved via mutations attenuating a vaccine in immune-deficient individuals without compromising the vaccine's performance in the normal host. We have addressed this hypothesis using a mouse model for Salmonella diarrhea and a live attenuated Salmonella Typhimurium strain (ssaV. Vaccination with this strain elicited protective immunity in wild type mice, but a fatal systemic infection in immune-deficient cybb(-/-nos2(-/- animals lacking NADPH oxidase and inducible NO synthase. In cybb(-/-nos2(-/- mice, we analyzed the attenuation of 35 ssaV strains carrying one additional mutation each. One strain, Z234 (ssaV SL1344_3093, was >1000-fold attenuated in cybb(-/-nos2(-/- mice and ≈100 fold attenuated in tnfr1(-/- animals. However, in wt mice, Z234 was as efficient as ssaV with respect to host colonization and the elicitation of a protective, O-antigen specific mucosal secretory IgA (sIgA response. These data suggest that it is possible to engineer live attenuated vaccines which are specifically attenuated in immuno-compromised hosts. This might help to improve vaccine safety.

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

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    Qiong Liu

    2016-03-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2016-03-22

    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.

  7. Comparative proteomic analysis of the PhoP regulon in Salmonella enterica serovar Typhi versus Typhimurium.

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    Richelle C Charles

    Full Text Available BACKGROUND: S. Typhi, a human-restricted Salmonella enterica serovar, causes a systemic intracellular infection in humans (typhoid fever. In comparison, S. Typhimurium causes gastroenteritis in humans, but causes a systemic typhoidal illness in mice. The PhoP regulon is a well studied two component (PhoP/Q coordinately regulated network of genes whose expression is required for intracellular survival of S. enterica. METHODOLOGY/PRINCIPAL FINDINGS: Using high performance liquid chromatography mass spectrometry (HPLC-MS/MS, we examined the protein expression profiles of three sequenced S. enterica strains: S. Typhimurium LT2, S. Typhi CT18, and S. Typhi Ty2 in PhoP-inducing and non-inducing conditions in vitro and compared these results to profiles of phoP(-/Q(- mutants derived from S. Typhimurium LT2 and S. Typhi Ty2. Our analysis identified 53 proteins in S. Typhimurium LT2 and 56 proteins in S. Typhi that were regulated in a PhoP-dependent manner. As expected, many proteins identified in S. Typhi demonstrated concordant differential expression with a homologous protein in S. Typhimurium. However, three proteins (HlyE, STY1499, and CdtB had no homolog in S. Typhimurium. HlyE is a pore-forming toxin. STY1499 encodes a stably expressed protein of unknown function transcribed in the same operon as HlyE. CdtB is a cytolethal distending toxin associated with DNA damage, cell cycle arrest, and cellular distension. Gene expression studies confirmed up-regulation of mRNA of HlyE, STY1499, and CdtB in S. Typhi in PhoP-inducing conditions. CONCLUSIONS/SIGNIFICANCE: This study is the first protein expression study of the PhoP virulence associated regulon using strains of Salmonella mutant in PhoP, has identified three Typhi-unique proteins (CdtB, HlyE and STY1499 that are not present in the genome of the wide host-range Typhimurium, and includes the first protein expression profiling of a live attenuated bacterial vaccine studied in humans (Ty800.

  8. Stress induced Salmonella Typhimurium recrudescence in pigs coincides with cortisol induced increased intracellular proliferation in macrophages

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    Verbrugghe Elin

    2011-12-01

    Full Text Available Abstract Salmonella Typhimurium infections in pigs often result in the development of carriers that intermittently excrete Salmonella in very low numbers. During periods of stress, for example transport to the slaughterhouse, recrudescence of Salmonella may occur, but the mechanism of this stress related recrudescence is poorly understood. Therefore, the aim of the present study was to determine the role of the stress hormone cortisol in Salmonella recrudescence by pigs. We showed that a 24 h feed withdrawal increases the intestinal Salmonella Typhimurium load in pigs, which is correlated with increased serum cortisol levels. A second in vivo trial demonstrated that stress related recrudescence of Salmonella Typhimurium in pigs can be induced by intramuscular injection of dexamethasone. Furthermore, we found that cortisol, but not epinephrine, norepinephrine and dopamine, promotes intracellular proliferation of Salmonella Typhimurium in primary porcine alveolar macrophages, but not in intestinal epithelial cells and a transformed cell line of porcine alveolar macrophages. A microarray based transcriptomic analysis revealed that cortisol did not directly affect the growth or the gene expression or Salmonella Typhimurium in a rich medium, which implies that the enhanced intracellular proliferation of the bacterium is probably caused by an indirect effect through the cell. These results highlight the role of cortisol in the recrudescence of Salmonella Typhimurium by pigs and they provide new evidence for the role of microbial endocrinology in host-pathogen interactions.

  9. Comprehensive identification of Salmonella enterica serovar typhimurium genes required for infection of BALB/c mice.

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    Roy R Chaudhuri

    2009-07-01

    Full Text Available Genes required for infection of mice by Salmonella Typhimurium can be identified by the interrogation of random transposon mutant libraries for mutants that cannot survive in vivo. Inactivation of such genes produces attenuated S. Typhimurium strains that have potential for use as live attenuated vaccines. A quantitative screen, Transposon Mediated Differential Hybridisation (TMDH, has been developed that identifies those members of a large library of transposon mutants that are attenuated. TMDH employs custom transposons with outward-facing T7 and SP6 promoters. Fluorescently-labelled transcripts from the promoters are hybridised to whole-genome tiling microarrays, to allow the position of the transposon insertions to be determined. Comparison of microarray data from the mutant library grown in vitro (input with equivalent data produced after passage of the library through mice (output enables an attenuation score to be determined for each transposon mutant. These scores are significantly correlated with bacterial counts obtained during infection of mice using mutants with individual defined deletions of the same genes. Defined deletion mutants of several novel targets identified in the TMDH screen are effective live vaccines.

  10. Detection of Salmonella typhimurium using phage-based magnetostrictive sensor

    Science.gov (United States)

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

    2006-05-01

    This article presents a contactless, remote sensing Salmonella typhimurium sensor based on the principle of magnetostriction. Magnetostrictive materials have been used widely for various types of sensor systems. In this work, the use of a magnetostrictive material for the detection of Salmonella typhimurium has been established. The mass of the bacteria attached to the sensor causes changes in the resonance frequency of the sensor. Filamentous bacteriophage was used as a probe order to ensure specific and selective binding of the bacteria onto the sensor surface. Thus changes in response of the sensor due to the mass added onto the sensor caused by specific attachment of bacteria can be monitored in absence of any contact to the sensor. The response of the sensor due to increasing concentrations (from 5x101 to 5x10 8 cfu/ml) of the bacteria was studied. A reduction in the physical dimensions enhances the sensitivity of these sensors and hence different dimensions of the sensor ribbons were studied. For a 2mm x 0.1mm x 0.02mm the detection limit was observed to be of the order of 10 4 cfu/mL and for a sensor of 1mm x 0.2mm x 0.02mm a reduced detection limit of 10 3 cfu/mL was achieved.

  11. The transcriptional landscape and small RNAs of Salmonella enterica serovar Typhimurium

    DEFF Research Database (Denmark)

    Kröger, Carsten; Dillon, Shane C.; Cameron, Andrew D. S.

    2012-01-01

    More than 50 y of research have provided great insight into the physiology, metabolism, and molecular biology of Salmonella enterica serovar Typhimurium (S. Typhimurium), but important gaps in our knowledge remain. It is clear that a precise choreography of gene expression is required for Salmone......More than 50 y of research have provided great insight into the physiology, metabolism, and molecular biology of Salmonella enterica serovar Typhimurium (S. Typhimurium), but important gaps in our knowledge remain. It is clear that a precise choreography of gene expression is required...

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

    Science.gov (United States)

    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.

  13. Virulent Salmonella enterica serovar typhimurium evades adaptive immunity by preventing dendritic cells from activating T cells.

    Science.gov (United States)

    Tobar, Jaime A; Carreño, Leandro J; Bueno, Susan M; González, Pablo A; Mora, Jorge E; Quezada, Sergio A; Kalergis, Alexis M

    2006-11-01

    Dendritic cells (DCs) constitute the link between innate and adaptive immunity by directly recognizing pathogen-associated molecular patterns (PAMPs) in bacteria and by presenting bacterial antigens to T cells. Recognition of PAMPs renders DCs as professional antigen-presenting cells able to prime naïve T cells and initiate adaptive immunity against bacteria. Therefore, interfering with DC function would promote bacterial survival and dissemination. Understanding the molecular mechanisms that have evolved in virulent bacteria to evade activation of adaptive immunity requires the characterization of virulence factors that interfere with DC function. Salmonella enterica serovar Typhimurium, the causative agent of typhoid-like disease in the mouse, can prevent antigen presentation to T cells by avoiding lysosomal degradation in DCs. Here, we show that this feature of virulent Salmonella applies in vivo to prevent activation of adaptive immunity. In addition, this attribute of virulent Salmonella requires functional expression of a type three secretion system (TTSS) and effector proteins encoded within the Salmonella pathogenicity island 2 (SPI-2). In contrast to wild-type virulent Salmonella, mutant strains carrying specific deletions of SPI-2 genes encoding TTSS components or effectors proteins are targeted to lysosomes and are no longer able to prevent DCs from activating T cells in vitro or in vivo. SPI-2 mutant strains are attenuated in vivo, showing reduced tissue colonization and enhanced T-cell activation, which confers protection against a challenge with wild-type virulent Salmonella. Our data suggest that impairment of DC function by the activity of SPI-2 gene products is crucial for Salmonella pathogenesis.

  14. ClpP deletion causes attenuation of Salmonella Typhimurium virulence through mis-regulation of RpoS and indirect control of CsrA and the SPI genes

    DEFF Research Database (Denmark)

    Knudsen, Gitte Maegaard; Olsen, John E.; Aabo, Søren;

    2013-01-01

    Salmonella enterica serovar Typhimurium requires the type III secretion system encoded by Salmonella pathogenicity island 1 (SPI1) and controlled by the master regulator, HilA, to penetrate the intestinal epithelium. Numerous regulators affect virulence through influence on this system, including...... the proteolytic component ClpP, the stationary phase regulator RpoS and the carbon-storage regulator CsrA. However, the mechanism behind the ClpP regulation is not fully understood. To elucidate this we examined differentially expressed genes in a ΔclpP mutant compared with WT using global transcriptomic analysis......, suggesting the repression of invasion was directed through RpoS. The expression of the csrA virulence regulator was increased in the ΔclpP mutant and decreased in the rpoS : : amp and ΔclpP/rpoS : : amp mutants, indicating that ClpP affects the csrA expression level as well. Thus, this study suggests...

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

    Directory of Open Access Journals (Sweden)

    Catherine M. McAuley

    2015-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    A Koluman

    2012-03-01

    Full Text Available 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.

  19. DNA methylation modulates Salmonella enterica serovar Typhimurium virulence in Caenorhabditis elegans.

    Science.gov (United States)

    Oza, Javin P; Yeh, Jimmy B; Reich, Norbert O

    2005-04-01

    Salmonella enterica serovar Typhimurium was previously shown to be virulent in Caenorhabditis elegans. Here we demonstrate that DNA adenine methyltransferase (DAM) modulates Salmonella virulence in the nematode, as it does in mice. After 5 days of continual exposure to bacteria, twice as many worms died when exposed to the wild-type than the dam-mutant strain of Salmonella. Similar trends in virulence were observed when worms were exposed to Salmonella strains for 5 h and transferred to the avirulent Escherichia coli OP50. While a 10-fold attenuation was observed in the absence of DAM, the dam-strain was still able to infect and persist in the host worm. Our results further support the use of C. elegans as an accessible and readily studied animal model of bacterial pathogenesis. However, our results suggest that crucial host responses differ between the murine and nematode models. Additionally, we carried out preliminary liquid culture based experiments with the long term goal of developing high throughput animal based screens of DAM inhibitors.

  20. Live Attenuated Human Salmonella Vaccine Candidates: Tracking the Pathogen in Natural Infection and Stimulation of Host Immunity.

    Science.gov (United States)

    Galen, James E; Buskirk, Amanda D; Tennant, Sharon M; Pasetti, Marcela F

    2016-11-01

    Salmonellosis, caused by members of the genus Salmonella, is responsible for considerable global morbidity and mortality in both animals and humans. In this review, we will discuss the pathogenesis of Salmonella enterica serovar Typhi and Salmonella enterica serovar Typhimurium, focusing on human Salmonella infections. We will trace the path of Salmonella through the body, including host entry sites, tissues and organs affected, and mechanisms involved in both pathogenesis and stimulation of host immunity. Careful consideration of the natural progression of disease provides an important context in which attenuated live oral vaccines can be rationally designed and developed. With this in mind, we will describe a series of attenuated live oral vaccines that have been successfully tested in clinical trials and demonstrated to be both safe and highly immunogenic. The attenuation strategies summarized in this review offer important insights into further development of attenuated vaccines against other Salmonella for which live oral candidates are currently unavailable.

  1. Genetic Characterization of the Galactitol Utilization Pathway of Salmonella enterica Serovar Typhimurium.

    Science.gov (United States)

    Nolle, Nicoletta; Felsl, Angela; Heermann, Ralf; Fuchs, Thilo M

    2017-02-15

    Galactitol degradation by salmonellae remains underinvestigated, although this metabolic capability contributes to growth in animals (R. R. Chaudhuri et al., PLoS Genet 9:e1003456, 2013, https://doi.org/10.1371/journal.pgen.1003456). The genes responsible for this metabolic capability are part of a 9.6-kb gene cluster that spans from gatY to gatR (STM3253 to STM3262) and encodes a phosphotransferase system, four enzymes, and a transporter of the major facilitator superfamily. Genome comparison revealed the presence of this genetic determinant in nearly all Salmonella strains. The generation time of Salmonella enterica serovar Typhimurium strain ST4/74 was higher in minimal medium with galactitol than with glucose. Knockout of STM3254 and gatC resulted in a growth-deficient phenotype of S Typhimurium, with galactitol as the sole carbon source. Partial deletion of gatR strongly reduced the lag phase of growth with galactitol, whereas strains overproducing GatR exhibited a near-zero growth phenotype. Luciferase reporter assays demonstrated strong induction of the gatY and gatZ promoters, which control all genes of this cluster except gatR, in the presence of galactitol but not glucose. Purified GatR bound to these two main gat gene cluster promoters as well as to its own promoter, demonstrating that this autoregulated repressor controls galactitol degradation. Surface plasmon resonance spectroscopy revealed distinct binding properties of GatR toward the three promoters, resulting in a model of differential gat gene expression. The cyclic AMP receptor protein (CRP) bound these promoters with similarly high affinities, and a mutant lacking crp showed severe growth attenuation, demonstrating that galactitol utilization is subject to catabolite repression. Here, we provide the first genetic characterization of galactitol degradation in Salmonella, revealing novel insights into the regulation of this dissimilatory pathway.

  2. Intracontinental spread of human invasive Salmonella Typhimurium pathovariants in sub-Saharan Africa.

    Science.gov (United States)

    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

    2012-11-01

    A highly invasive form of non-typhoidal Salmonella (iNTS) disease has recently been documented in many countries in sub-Saharan Africa. The most common Salmonella enterica serovar causing this disease is Typhimurium (Salmonella Typhimurium). We applied whole-genome sequence-based phylogenetic methods to define the population structure of sub-Saharan African invasive Salmonella Typhimurium isolates and compared these to global Salmonella Typhimurium populations. Notably, the vast majority of sub-Saharan invasive Salmonella Typhimurium isolates 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 from lineage I by those from 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.

  3. Innate immune control of Salmonella enterica serovar Typhimurium: mechanisms contributing to combating systemic Salmonella infection.

    Science.gov (United States)

    Wick, Mary Jo

    2011-01-01

    Infections with Salmonella enterica serovars remain a serious problem worldwide. While serovar Typhi causes significant morbidity and mortality that is restricted to humans, serovar Typhimurium causes gastroenteritidis in humans and can also infect other animals. As mice with the susceptible Nramp1 locus get systemic infection with serovar Typhimurium, murine infection models using this serovar have been widely used to decipher the immune mechanisms required to survive systemic Salmonella infection. This review summarizes recent studies in murine infection models that have advanced our understanding of the events that occur during the first days after oral Salmonella infection. The pathways of bacterial penetration across the intestinal epithelium, bacterial spread to draining (mesenteric) lymph nodes and dissemination to systemic tissues is discussed. The response of myeloid cell populations, including dendritic cells, inflammatory monocytes and neutrophils, during the early stage of infection is also discussed. Finally, the mechanisms driving recruitment of myeloid cells to infected intestinal lymphoid tissues and what is known about Toll-like receptor signaling pathways in innate immunity to Salmonella infection is also discussed.

  4. Immunogenicity of a Bivalent Adjuvanted Glycoconjugate Vaccine against Salmonella Typhimurium and Salmonella Enteritidis

    Science.gov (United States)

    Fiorino, Fabio; Rondini, Simona; Micoli, Francesca; Lanzilao, Luisa; Alfini, Renzo; Mancini, Francesca; MacLennan, Calman A.; Medaglini, Donata

    2017-01-01

    Salmonella enterica serovars Typhimurium and Enteritidis are the predominant causes of invasive non-typhoidal Salmonella (iNTS) disease. Considering the co-endemicity of S. Typhimurium and S. Enteritidis, a bivalent vaccine formulation against both pathogens is necessary for protection against iNTS disease, thus investigation of glycoconjugate combination is required. In the present work, we investigated the immune responses induced by S. Typhimurium and S. Enteritidis monovalent and bivalent glycoconjugate vaccines adjuvanted with aluminum hydroxide (alum) only or in combination with cytosine-phosphorothioate-guanine oligodeoxynucleotide (CpG). Humoral and cellular, systemic and local, immune responses were characterized in two different mouse strains. All conjugate vaccines elicited high levels of serum IgG against the respective O-antigens (OAg) with bactericidal activity. The bivalent conjugate vaccine induced systemic production of antibodies against both S. Typhimurium and S. Enteritidis OAg. The presence of alum or alum + CpG adjuvants in vaccine formulations significantly increased the serum antigen-specific antibody production. The alum + CpG bivalent vaccine formulation triggered the highest systemic anti-OAg antibodies and also a significant increase of anti-OAg IgG in intestinal washes and fecal samples, with a positive correlation with serum levels. These data demonstrate the ability of monovalent and bivalent conjugate vaccines against S. Typhimurium and S. Enteritidis to induce systemic and local immune responses in different mouse strains, and highlight the suitability of a bivalent glycoconjugate formulation, especially when adjuvanted with alum + CpG, as a promising candidate vaccine against iNTS disease. PMID:28289411

  5. Radiation-induced mutagenicity and lethality in Salmonella typhimurium

    Energy Technology Data Exchange (ETDEWEB)

    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)

  6. Mutagenicity study of butachlor and its metabolites using Salmonella typhimurium.

    Science.gov (United States)

    Hsu, Kuei-Yao; Lin, Hwai-Jeng; Lin, Jen-Kun; Kuo, Wein-Shung; Ou, Yueh-Hsing

    2005-12-01

    Butachlor is the most commonly used herbicide in Taiwan and many other countries. It has been reported to be an indirect mutagen and carcinogen in various in vitro assay systems. Previous investigation has also demonstrated that butachlor stimulates cell proliferation, transforms normal embryonic cells, and induces stomach tumors in Spraque-Dawley rats. However, the mechanism of butachlor carcinogenicity is still not clear. In order to clarify the toxicologic and carcinogenic properties of butachlor, we proposed a metabolic pathway, and synthesized the authentic metabolites by chemical methods. In addition, we tested the mutagenicity of butachlor and these metabolites on Salmonella typhimurium. The results indicate that butachlor might manifest its carcinogenicity via the mutagenicity of its metabolic products. Although the molecular mechanism of butachlor-induced cellular toxicity is still not clear, it is likely that the cellular transformation ability of butachlor is partly associated with its mutagenicity.

  7. Regulation of biofilm formation in Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Simm, Roger; Ahmad, Irfan; Rhen, Mikael; Le Guyon, Soazig; Römling, Ute

    2014-01-01

    In animals, plants and the environment, Salmonella enterica serovar Typhimurium forms the red dry and rough (rdar) biofilm characterized by extracellular matrix components curli and cellulose. With complex expression control by at least ten transcription factors, the bistably expressed orphan response regulator CsgD directs rdar morphotype development. CsgD expression is an integral part of the Hfq regulon and the complex cyclic diguanosine monophosphate signaling network partially controlled by the global RNA-binding protein CsrA. Cell wall turnover and the periplasmic redox status regulate csgD expression on a post-transcriptional level by unknown mechanisms. Furthermore, phosphorylation of CsgD is a potential inactivation and degradation signal in biofilm dissolution. Including complex incoherent feed-forward loops, regulation of biofilm formation versus motility and virulence is of recognized complexity.

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

    Science.gov (United States)

    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.

  9. Characterization of a Salmonella typhimurium mutant defective in phosphoribosylpyrophosphate synthetase

    DEFF Research Database (Denmark)

    Jochimsen, Bjarne; Hove-Jensen, Bjarne; Garber, Bruce B.;

    1985-01-01

    This study describes the isolation and characterization of a mutant (strain GP122) of Salmonella typhimurium with a partial deficiency of phosphoribosylpyrophosphate (PRPP) synthetase activity. This strain was isolated in a purE deoD gpt purine auxotroph by a procedure designed to select guanosine......-utilizing mutants. Strain GP122 had roughly 15% of the PRPP synthetase activity and 25% of the PRPP pool of its parent strain. The mutant exhibited many of the predicted consequences of a decreased PRPP pool and a defective PRPP synthetase enzyme, including: poor growth on purine bases; decreased accumulation of 5...... phosphoribosyltransferase, enzymes involved in the pyrimidine de novo biosynthetic pathway; growth stimulation by PRPP-sparing compounds (e.g. guanosine, histidine); poor growth in low phosphate medium; and increased heat lability of the defective enzyme. This mutant strain also had increased levels of guanosine 5...

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

    OpenAIRE

    2013-01-01

    Salmonella enterica serotype Typhimurium is one of the leading causes of salmonellosis in Mauritius, where it has also been associated with outbreaks of foodborne illness. However, little is known about its molecular epidemiology in the country. This study was therefore undertaken to investigate the clonality and source of Salmonella Typhimurium in Mauritius by studying human, food, and poultry isolates by pulsed-field gel electrophoresis (PFGE) and antibiotic minimum inhibitory concentration...

  11. Structure of the gene encoding phosphoribosylpyrophosphate synthetase (prsA>) in Salmonella typhimurium

    DEFF Research Database (Denmark)

    Bower, Stanley G.; Hove-Jensen, Bjarne; Switzer, Robert L.

    1988-01-01

    The Salmonella typhimurium gene prsA, which encodes phosphoribosylpyrophosphate synthetase, has been cloned, and the nucleotide sequence has been determined. The amino acid sequence derived from the S. typhimurium gene is 99% identical to the derived Escherichia coli sequence and 47% identical to...

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    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...

  13. Biological and virulence characteristics of Salmonella enterica serovar Typhimurium following deletion of glucose-inhibited division (gidA) gene.

    Science.gov (United States)

    Shippy, Daniel C; Eakley, Nicholas M; Bochsler, Philip N; Chopra, Ashok K; Fadl, Amin A

    2011-06-01

    Salmonella enterica serovar Typhimurium is a frequent cause of enteric disease due to the consumption of contaminated food. Identification and characterization of bacterial factors involved in Salmonella pathogenesis would help develop effective strategies for controlling salmonellosis. To investigate the role of glucose-inhibited division gene (gidA) in Salmonella virulence, we constructed a Salmonella mutant strain in which gidA was deleted. Deletion of gidA rendered Salmonella deficient in the invasion of intestinal epithelial cells, bacterial motility, intracellular survival, and induction of cytotoxicity in host cells. Deletion of gidA rendered the organism to display a filamentous morphology compared to the normal rod-shaped nature of Salmonella. Furthermore, a significant attenuation in the induction of inflammatory cytokines and chemokines, histopathological lesions, and systemic infection was observed in mice infected with the gidA mutant. Most importantly, a significant increase in LD(50) was observed in mice infected with the gidA mutant, and mice immunized with the gidA mutant were able to survive a lethal dose of wild-type Salmonella. Additionally, deletion of gidA significantly altered the expression of several bacterial factors associated with pathogenesis as indicated by global transcriptional and proteomic profiling. Taken together, our data indicate GidA as a potential regulator of Salmonella virulence genes.

  14. Hysteresis in myo-inositol utilization by Salmonella Typhimurium.

    Science.gov (United States)

    Hellinckx, Jessica; Fuchs, Thilo M

    2016-12-27

    Growth of Salmonella enterica serovar Typhimurium strain 14028 with myo-inositol (MI) as the sole carbon and energy source is characterized by a bistable phenotype that manifests in a growth phenotype with an extraordinarily long and length-variable lag phase. However, in the presence of hydrogen carbonate, in the absence of IolR that represses the MI degradation pathway, or if cells are already adapted to minimal medium (MM) with MI, the lag phase is drastically shortened, and the bistable phenotype is abolished. We hypothesized that memory development or hysteresis is a further characteristic of MI degradation by S. Typhimurium; therefore, we investigated the transition from a short to a long lag phase in more detail. Growth experiments demonstrated that memory on the population level is successively lost within approximately 8 hr after cells, which had been adapted to MI utilization, were transferred to lysogeny broth (LB) medium. Flow cytometry (FC) analysis using a chromosomal fusion to PiolE , a promoter controlling the expression of the enzymatic genes iolE and iolG involved in MI degradation, indicated a gradual reversion within a few hours from a population in the "ON" status with respect to iolE transcription to one that is mainly in the "OFF" status. Growth and FC experiments revealed that IolR does not affect hysteresis.

  15. The detection of Salmonella typhimurium on shell eggs using a phage-based biosensor

    Science.gov (United States)

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

    2011-06-01

    This paper presents the direct detection of Salmonella typhimurium on shell eggs using a phage-based magnetoelastic (ME) biosensor. The ME biosensor consists of a ME resonator as the sensor platform and E2 phage as the biorecognition element that is genetically engineered to specifically bind with Salmonella typhimurium. The ME biosensor, which is a wireless sensor, vibrates with a characteristic resonant frequency under an externally applied magnetic field. Multiple sensors can easily be remotely monitored. Multiple measurement and control sensors were placed on the shell eggs contaminated by Salmonella typhimurium solutions with different known concentrations. The resonant frequency of sensors before and after the exposure to the spiked shell eggs was measured. The frequency shift of the measurement sensors was significantly different than the control sensors indicating Salmonella contamination. Scanning electron microscopy was used to confirm binding of Salmonella to the sensor surface and the resulting frequency shift results.

  16. 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

    Directory of Open Access Journals (Sweden)

    Verbrugghe Elin

    2012-03-01

    Full Text Available Abstract 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.

  17. Characterization of Salmonella Enterica Serotype Typhimurium from Outpatients of 28 Hospitals in Henan Province in 2006

    Institute of Scientific and Technical Information of China (English)

    MIN ZHU; ZHI-QIANG XIE; LI-SHI ZHANG; SHENG-LI XIA; WEI-ZHONG YANG; LU RAN; ZI-JUN WANG

    2009-01-01

    Objective To characterize the diarrheal patients with Salmonella typhimurium (S. typhimurium) infections and to set up the first baseline for 5. typhimurium pulsed-field gel electrophoresis (PFGE) patterns in Henan province, thus laying a foundation for comprehensive surveillance of Salmonella in human as well as foods. Methods S. typhimurium isolates recovered from outpatients with diarrhea in Henan province from May to October of 2006 were characterized. Antimicrobial susceptibility tests of 8 antimicrobial agents and PFGE were carried out to analyze the 5. typhimurium isolates. Results Twenty-four (0.9%) S. typhimurium isolates were identified from 2661 stool specimens of diarrheal cases. Eighty-eight percent of isolates showed resistance to at least one antimicrobial agent. The resistance to chloramphenicol (79%) was most common. Fifty-eight percent of isolates were resistant to ciprofloxacin. All the 14 ciprofloxacin-resistant isolates were resistant to more than five antimicrobial agents. Thirty-three percent of 5. typhimurium isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (R-type ACSSuT). Eight antimicrobia-resistant phenotypes were found among the 24 isolates in 16 PFGE patterns. Conclusion The rate of multidrug-resistant S. typhimurium is relatively high in S. typhimurium PFGE patterns of Henan province. Multidrug-resistant S. typhimurium should be considered a public health threat.

  18. Molecular analysis of the Salmonella typhimurium tdc operon regulation.

    Science.gov (United States)

    Kim, Min-Jeong; Lim, Sangyong; Ryu, Sangryeol

    2008-06-01

    Efficient expression of the Salmonella Typhimurium tdcABCDEG operon involved in the degradation of Lserine and L-threonine requires TdcA, the transcriptional activator of the tdc operon. We found that the tdcA gene was transiently activated when bacterial growth condition was changed from aerobic to anaerobic, but this was not observed if Salmonella was grown anaerobically from the beginning of the culture. Expression kinetics of six tdc genes after anaerobic shock demonstrated by a real-time PCR assay showed that the tdcCDEG genes were not induced in tdcA mutant but tdcB maintained its inducibility by anaerobic shock even in the absence of tdcA, suggesting that an additional unknown transcriptional regulation may work for the tdcB expression. We also investigated the effects of nucleoid-associated proteins by primer extension analysis and found that H-NS repressed tdcA under anaerobic shock conditions and fis mutation delayed the peak expression time of the tdc operon. DNA microarray analysis of genes regulated by TdcA revealed that the genes involved in Nacetylmannosamine, maltose, and propanediol utilization were significantly induced in a tdcA mutant. These findings suggest that Tdc enzymes may play a pivotal role in energy metabolism under a sudden change of oxygen tension.

  19. Construction and identification of a recombinant attenuated Salmonella typhimurium vaccine strain expressing Helicobacter pylori hpaA gene%表达幽门螺杆菌hpaA重组减毒鼠伤寒沙门氏菌的构建和鉴定

    Institute of Scientific and Technical Information of China (English)

    朱森林; 陈旻湖; 廖文俊; 陈洁; 胡品津

    2001-01-01

    Objective: To construct a recombinant live attenuated Salmonellaty phimurium vaccine strain expressing Helicobacter pylori hpaA gene.Methods: By g enetic engineering methods,hpaA gene was cloned into a procaryotic expression pl asmid pTrc99A,and the identified recombinant plasmid was then used to transform an attenuated Salmonella typhimurium vaccine strain SL3261,and the positive clon es were screened by PCR and restriction enzyme digestion. HpaA expression was an alyzed by SDS-PAGE and Western blot.Results:Confirmed by PCR and restriction en zyme digestion ,a recombinant procaryotic expression plasmid pTrc99A-hpaA was c o nstructed,and then introduced into an attenuated Sa lmonella typhimurium vaccine strain SL3261 successfully. HpaA was expressed in t he recombinant strains in the form of a dimer,and also its immunogenicity was co nfirmed by Western blot. Conclusion: A recombinant live attenuated Salmonella ty phimurium vaccine strain expressing Helicobacter pylori hpaA gene was constructe d and identified,and this work will help to develop an oral recombinant live vac cine against Helicobacter pylori.%目的:构建表达幽门螺杆菌(H.pylori)hpaA的重组减毒鼠伤寒沙门氏疫苗菌。方法:用基因工程的方法将hpaA基因克隆入原核表达质粒pTrc99A,并进行了基因测序。重组质粒经鉴定后再导入减毒鼠伤寒沙门氏菌SL3261,提取重组疫苗菌质粒,PCR和酶切鉴定,筛选阳性克隆。用SDS-PAGE电泳和Westernblot进行HpaA表达和鉴定。结果:经PCR和酶切证实,构建了含hpaA的重组原核表达质粒pTrc99A-hpaA,并将后者成功转化了减毒鼠伤寒沙门氏菌。HpaA能在疫苗菌中以二聚体形式表达,HpaA量约占全菌体蛋白量的17%,Westernblot证实其有免疫原性。结论:构建了表达H.pylorihpaA的重组减毒鼠伤寒沙门氏疫苗菌,为探索制备H.pylori口服活疫苗奠定了基础。

  20. Identification of immunogenic proteins and generation of antibodies against Salmonella Typhimurium using phage display

    Directory of Open Access Journals (Sweden)

    Meyer Torsten

    2012-06-01

    Full Text Available Abstract Background Solely in Europoe, Salmonella Typhimurium causes more than 100,000 infections per year. Improved detection of livestock colonised with S. Typhimurium is necessary to prevent foodborne diseases. Currently, commercially available ELISA assays are based on a mixture of O-antigens (LPS or total cell lysate of Salmonella and are hampered by cross-reaction. The identification of novel immunogenic proteins would be useful to develop ELISA based diagnostic assays with a higher specificity. Results A phage display library of the entire Salmonella Typhimurium genome was constructed and 47 immunogenic oligopeptides were identified using a pool of convalescent sera from pigs infected with Salmonella Typhimurium. The corresponding complete genes of seven of the identified oligopeptids were cloned. Five of them were produced in E. coli. The immunogenic character of these antigens was validated with sera from pigs infeced with S. Tyhimurium and control sera from non-infected animals. Finally, human antibody fragments (scFv against these five antigens were selected using antibody phage display and characterised. Conclusion In this work, we identified novel immunogenic proteins of Salmonella Typhimurium and generated antibody fragments against these antigens completely based on phage display. Five immunogenic proteins were validated using a panel of positive and negative sera for prospective applications in diagnostics of Salmonela Typhimurium.

  1. Antigenic role of stress-induced catalase of Salmonella typhimurium in cell-mediated immunity.

    OpenAIRE

    Kagaya, K; Miyakawa, Y; Watanabe, K; Fukazawa, Y.

    1992-01-01

    The ability of the H2O2-induced catalase of Salmonella typhimurium to induce cell-mediated immunity against S. typhimurium infection in mice was examined. When exponentially growing cells of S. typhimurium were treated with 20 microM H2O2, the cells resisted killing by 1 mM H2O2 and showed the induction of a new species of catalase in addition to the constitutively produced one. Two molecules of catalases in S. typhimurium were isolated from mutant strains: H2O2-induced catalase (catalase II,...

  2. A Descriptive Study of Human Salmonella Serotype Typhimurium Infections Reported in Ontario from 1990 to 1997

    Directory of Open Access Journals (Sweden)

    Michael W Ford

    2003-01-01

    Full Text Available BACKGROUND: Salmonella infections cause gastrointestinal and systemic diseases worldwide and are the leading causes of food-borne illnesses in North America (1-4. Salmonella serotype typhimurium (ST, in particular, is increasingly becoming a major public health concern because of its ability to acquire multiple resistant genes (5,6.

  3. Practical considerations on surveillance of Salmonella serovars other than Enteritidis and Typhimurium

    DEFF Research Database (Denmark)

    Wagenaar, J. A.; Hendriksen, Rene S.; Carrigue-Mas, J.

    2013-01-01

    Non-typhoid Salmonella serovars other than Salmonella enterica serovars S. Enteritidis (SE) and S. Typhimurium (ST) are isolated throughout the world with huge variations in prevalence. Besides the more generally occurring serovars, such as S. Infantis and S. Hadar, there are many examples...

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

    Science.gov (United States)

    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...

  5. Molecular characterization of "inconsistent" variants of Salmonella Typhimurium isolated in Italy

    DEFF Research Database (Denmark)

    Barco, Lisa; Longo, Alessandra; Lettini, Antonia Anna

    2014-01-01

    Salmonella 4,[5],12:i:- is a variant of Salmonella Typhimurium, which lacks the expression of phase-2 flagellar antigen, generally associated with the deletion of the fljB gene. Additional mechanisms involving the fljAB operon ( fljA, fljB, and hin genes) lead to the lack of expression of phase-2...

  6. Signatures of adaptation in human invasive Salmonella Typhimurium ST313 populations from sub-Saharan Africa.

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    Chinyere K Okoro

    2015-03-01

    Full Text Available 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.

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

    Directory of Open Access Journals (Sweden)

    F.G. Paião

    2013-01-01

    Full Text Available 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 ºC 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.

  8. Chicken serologic response to Salmonella enterica serotype Typhimurium assessed by Elisa

    Directory of Open Access Journals (Sweden)

    GH Oliveira

    2006-03-01

    Full Text Available This study evaluated two enzyme-linked immunosorbent assays (ELISA in the detection of chicken serologic response against Salmonella enterica sorotype Typhimurium. The assays have used as detecting antigen the soluble bacterial proteins of a non-flagellated strain of Salmonella Typhimurium (AgTM, and antibody conjugated to peroxidase or alkaline phosphatase. According to the results, optimal dilutions of antigen (concentration 5.49 mg/mL and serum samples in both assays were 1:20,000 and 1:1,000, respectively. In such conditions, the ELISA/AgTM was able to detect serological response to Salmonella Typhimurium. Cross-reactions to Salmonella serotypes Gallinarum and Pullorum were seen, but not with other serotypes such as Enteritidis.

  9. Interaction of Salmonella enterica Serovar Typhimurium with Intestinal Organoids Derived from Human Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Forbester, Jessica L; Goulding, David; Vallier, Ludovic; Hannan, Nicholas; Hale, Christine; Pickard, Derek; Mukhopadhyay, Subhankar; Dougan, Gordon

    2015-07-01

    The intestinal mucosa forms the first line of defense against infections mediated by enteric pathogens such as salmonellae. Here we exploited intestinal "organoids" (iHOs) generated from human induced pluripotent stem cells (hIPSCs) to explore the interaction of Salmonella enterica serovar Typhimurium with iHOs. Imaging and RNA sequencing were used to analyze these interactions, and clear changes in transcriptional signatures were detected, including altered patterns of cytokine expression after the exposure of iHOs to bacteria. S. Typhimurium microinjected into the lumen of iHOs was able to invade the epithelial barrier, with many bacteria residing within Salmonella-containing vacuoles. An S. Typhimurium invA mutant defective in the Salmonella pathogenicity island 1 invasion apparatus was less capable of invading the iHO epithelium. Hence, we provide evidence that hIPSC-derived organoids are a promising model of the intestinal epithelium for assessing interactions with enteric pathogens.

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

    Science.gov (United States)

    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.

  11. LPS structure and PhoQ activity are important for Salmonella Typhimurium virulence in the Galleria mellonella infection model [corrected].

    Directory of Open Access Journals (Sweden)

    Jennifer K Bender

    Full Text Available The larvae of the wax moth, Galleria mellonella, have been used experimentally to host a range of bacterial and fungal pathogens. In this study we evaluated the suitability of G. mellonella as an alternative animal model of Salmonella infection. Using a range of inoculum doses we established that the LD₅₀ of SalmonellaTyphimurium strain NCTC 12023 was 3.6 × 10³ bacteria per larva. Further, a set of isogenic mutant strains depleted of known virulence factors was tested to identify determinants essential for S. Typhimurium pathogenesis. Mutants depleted of one or both of the type III secretion systems encoded by Salmonella Pathogenicity Islands 1 and 2 showed no virulence defect. In contrast, we observed reduced pathogenic potential of a phoQ mutant indicating an important role for the PhoPQ two-component signal transduction system. Lipopolysaccharide (LPS structure was also shown to influence Salmonella virulence in G. mellonella. A waaL(rfaL mutant, which lacks the entire O-antigen (OAg, was virtually avirulent, while a wzz(ST/wzz(fepE double mutant expressing only a very short OAg was highly attenuated for virulence. Furthermore, shortly after infection both LPS mutant strains showed decreased replication when compared to the wild type in a flow cytometry-based competitive index assay. In this study we successfully established a G. mellonella model of S. Typhimurium infection. By identifying PhoQ and LPS OAg length as key determinants of virulence in the wax moth larvae we proved that there is an overlap between this and other animal model systems, thus confirming that the G. mellonella infection model is suitable for assessing aspects of Salmonella virulence function.

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

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    Lieze Oscar Rouffaer

    Full Text Available 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.

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

    Science.gov (United States)

    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: 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.

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

    Directory of Open Access Journals (Sweden)

    Bogomolnaya Lydia M

    2008-10-01

    Full Text Available Abstract 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.

  15. Genomic Analysis of Salmonella enterica Serovar Typhimurium from Wild Passerines in England and Wales.

    Science.gov (United States)

    Mather, Alison E; Lawson, Becki; de Pinna, Elizabeth; Wigley, Paul; Parkhill, Julian; Thomson, Nicholas R; Page, Andrew J; Holmes, Mark A; Paterson, Gavin K

    2016-11-15

    Passerine salmonellosis is a well-recognized disease of birds in the order Passeriformes, which includes common songbirds such as finches and sparrows, caused by infection with Salmonella enterica serovar Typhimurium. Previous research has suggested that some subtypes of S Typhimurium-definitive phage types (DTs) 40, 56 variant, and 160-are host adapted to passerines and that these birds may represent a reservoir of infection for humans and other animals. Here, we have used the whole-genome sequences of 11 isolates from British passerines, five isolates of similar DTs from humans and a domestic cat, and previously published S Typhimurium genomes that include similar DTs from other hosts to investigate the phylogenetic relatedness of passerine salmonellae to other S Typhimurium isolates and investigate possible genetic features of the distinct disease pathogenesis of S Typhimurium in passerines. Our results demonstrate that the 11 passerine isolates and 13 other isolates, including those from nonpasserine hosts, were genetically closely related, with a median pairwise single nucleotide polymorphism (SNP) difference of 130 SNPs. These 24 isolates did not carry antimicrobial resistance genetic determinants or the S Typhimurium virulence plasmid. Although our study does not provide evidence of Salmonella transmission from passerines to other hosts, our results are consistent with the hypothesis that wild birds represent a potential reservoir of these Salmonella subtypes, and thus, sensible personal hygiene precautions should be taken when feeding or handling garden birds.

  16. Role in virulence and protective efficacy in pigs of Salmonella enterica serovar Typhimurium secreted components identified by signature-tagged mutagenesis.

    Science.gov (United States)

    Carnell, Sonya C; Bowen, Alison; Morgan, Eirwen; Maskell, Duncan J; Wallis, Timothy S; Stevens, Mark P

    2007-06-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) is a zoonotic enteric pathogen of worldwide importance and pigs are a significant reservoir of human infection. Signature-tagged transposon mutagenesis (STM) was used to identify genes required by S. Typhimurium to colonize porcine intestines. A library of 1045 signature-tagged mutants of S. Typhimurium ST4/74 Nal(R) was screened following oral inoculation of pigs in duplicate. A total of 119 attenuating mutations were identified in 95 different genes, many of which encode known or putative secreted or surface-anchored molecules. A large number of attenuating mutations were located within Salmonella pathogenicity islands (SPI)-1 and -2, confirming important roles for type III secretion systems (T3SS)-1 and -2 in intestinal colonization of pigs. Roles for genes encoded in other pathogenicity islands and islets, including the SPI-6-encoded Saf atypical fimbriae, were also identified. Given the role of secreted factors and the protection conferred against other pathogens by vaccination with extracellular and type III secreted proteins, the efficacy of a secreted protein vaccine from wild-type S. Typhimurium following intramuscular vaccination of pigs was evaluated. Serum IgG responses against type III secreted proteins were induced following vaccination and a significant reduction in faecal excretion of S. Typhimurium was observed in the acute phase of infection compared to mock-vaccinated animals. Vaccination with secreted proteins from an isogenic S. Typhimurium prgH mutant produced comparable levels of protection to vaccination with the preparation from the parent strain, indicating that protection was not reliant on T3SS-1 secreted proteins. The data provide valuable information for the control of Salmonella in pigs.

  17. Coordinated regulation of virulence during systemic infection of Salmonella enterica serovar Typhimurium.

    Directory of Open Access Journals (Sweden)

    Hyunjin Yoon

    2009-02-01

    Full Text Available To cause a systemic infection, Salmonella must respond to many environmental cues during mouse infection and express specific subsets of genes in a temporal and spatial manner, but the 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 83 regulators inferred to play a role in Salmonella enteriditis Typhimurium (STM virulence and tested them in three virulence assays (intraperitoneal [i.p.], and intragastric [i.g.] infection in BALB/c mice, and persistence in 129X1/SvJ mice. Overall, 35 regulators were identified whose absence attenuated virulence in at least one assay, and of those, 14 regulators were required for systemic mouse infection, the most stringent virulence assay. As a first step towards understanding the interplay between a pathogen and its host from a systems biology standpoint, we focused on these 14 genes. Transcriptional profiles were obtained for deletions of each of these 14 regulators 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 14 regulators control the same 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 the response regulator SsrB and the MarR type regulator, SlyA, are the terminal regulators in a cascade that integrates multiple signals. Furthermore, experiments to demonstrate epistatic relationships showed that SsrB can replace SlyA and, in some cases, SlyA can replace SsrB for expression of SPI-2 encoded

  18. Distribution of Salmonella enterica serovars from humans, livestock and meat in Vietnam and the dominance of Salmonella Typhimurium phage type 90.

    NARCIS (Netherlands)

    Vo, An T T; Duijkeren, Engeline van; Fluit, Ad C; Heck, Max E O C; Verbruggen, Anjo J; Maas, Henny M E; Gaastra, Wim

    2006-01-01

    Epidemiologically unrelated non-typhoid Salmonella isolates from humans (n = 56) and animal origin (n = 241, from faeces, carcasses and meat) in Vietnam were investigated. Salmonella Typhimurium, S. Anatum, S. Weltevreden, S. Emek, and S. Rissen were the most prevalent serovars. S. Typhimurium phage

  19. Molecular characterization of Salmonella Typhimurium highly successful outbreak strains.

    Science.gov (United States)

    Petersen, Randi Føns; Litrup, Eva; Larsson, Jonas T; Torpdahl, Mia; Sørensen, Gitte; Müller, Luise; Nielsen, Eva M

    2011-06-01

    Three large clusters of Salmonella Typhimurium infections in Denmark in 2008 and 2009 were defined by multilocus variable number of tandem repeat analysis (MLVA). One of these proved to be the hereto largest Danish cluster of salmonellosis with 1446 cases. Two smaller clusters with a total of 197 and 89 cases, respectively, were seen concurrently. These clusters shared epidemiological characteristics such as age distribution, geography, and time. To investigate the possible genetic relationship between the cluster strains, these were further characterized by phage typing, pulsed-field gel electrophoresis, and Optical Mapping. Although the MLVA method proved robust and well-performing in detecting and defining clusters, the employment of a second typing method detected an additional fourth cluster among the isolates. The cluster strains were stable throughout the almost 2-year period, even though we detected changes in three of five MLVA loci in a small fraction of isolates. These changes were mainly due to the gain or loss of single repeats. Optical Mapping of the large cluster strain indicated no increased content of virulence genes; however, Optical Mapping did reveal a large insert, a probable prophage, in the main cluster. This probable prophage may give the cluster strain a competitive advantage. The molecular methods employed suggested that the four clusters represented four distinct strains, although they seemed to be epidemiologically linked and shared genotypic characteristics.

  20. Genome Sequences of Three Highly Copper-Resistant Salmonella enterica subsp. I Serovar Typhimurium Strains Isolated from Pigs in Denmark

    DEFF Research Database (Denmark)

    Qin, Yanan; Hasman, Henrik; Aarestrup, Frank Møller;

    2014-01-01

    Salmonella typhimurium is the causative agent of typhoid fever, which causes nearly 21.7 million illnesses and 217,000 deaths around the world each year. Here, we describe the draft genome sequences of the Salmonella typhimurium strains S7, S15, and S23, isolated from copper-fed pigs in Denmark...

  1. Behavior of Salmonella Typhimurium in pork minced meat and pork skin at different storage temperatures

    Directory of Open Access Journals (Sweden)

    Karabasil Neđeljko

    2013-01-01

    Full Text Available Salmonella is a common contaminant of pork and can present a health hazard to consumers. Therefore, for an effective control, the entire supply chain must be involved. The aim of this paper is to examine the survival of Salmonella Typhimurium in pork minced meat and skin at different temperatures and time. In minced meat, stored at +4 ± 0.5°C during 72 h, the number of Salmonella Typhimurium of all three examined strains A, B, and C decreased (p0.05. On the skin, stored at +4 ± 0.5°C during 72 h, the number of Salmonella of strains A and B decreased (p0.05. On the skin, stored at +10 ± 1°C during 72 h, the number of Salmonella of strains A and C decreased (p0.05.

  2. The use of tannins to control Salmonella typhimurium infections in pigs.

    Science.gov (United States)

    Van Parys, A; Boyen, F; Dewulf, J; Haesebrouck, F; Pasmans, F

    2010-09-01

    The aim of this study was to determine whether a hydrolysable tannin extract of sweet chestnut wood (Globatan(®)) has an inhibitory effect on Salmonella Typhimurium survival both in vitro and in vivo in pigs. In a first experiment, the minimal inhibitory concentration of Globatan(®) on 57 Salmonella Typhimurium isolates was determined. For all isolates, an MIC of 160-320 μg/ml was found. The second in vitro study revealed that Salmonella growth was strongly reduced using Globatan(®) concentrations of 25-50 μg/ml and nearly completely inhibited at a concentration of 100 μg/ml Globatan(®). In an in vivo trial, two groups of six piglets, each group receiving feed with or without the addition of Globatan(®) (3 g/kg), were orally inoculated with 10(7) colony forming units of a Salmonella Typhimurium strain. Globatan(®) had no effect on faecal excretion of Salmonella, and no differences in colonization of the intestines and internal organs were demonstrated in pigs euthanized at 4 days post-inoculation. In conclusion, the hydrolysable tannin extract used in this study showed strong action against Salmonella Typhimurium in vitro but not in vivo.

  3. Performance of broilers experimentally inoculated with Salmonella Typhimurium and fed diets with addition of lactulosis

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    Eliete Souza Santana

    2012-08-01

    Full Text Available The objective of this experiment was to evaluate the influence of lactulose on performance as well as its ability to prevent colonization by Salmonella Typhimurium in broilers orally inoculated with this pathogen. The design adopted was completely randomized, with 630 one-day-old male chicks distributed into six treatments, with seven replications and 15 birds per experimental unit. The treatments comprised the following procedures: T1 (control group - no S. Typhimurium inoculation or supply of lactulosis; T2 - only inoculation of S. Typhimurium; T3 - only lactulosis supply; T4 supply of lactulosis and S. Typhimurium inoculation on the first day of life; T5 - supply of lactulosis 48 hours before S. Typhimurium inoculation; and T6 - supply of lactulosis 48 hours after inoculation of S. Typhimurium. Performance variables were evaluated on the seventh, 14th, 21st and 28th days of age; fragments of the duodenum and jejunum were collected and sent to histomorphometric assessment at 14 days of age, and S. Typhimurium excretion was verified in cloacal swabs on the 10th, 24th and 35th days of age. Performance data were analyzed by ANOVA and Tukey's test (5% and fecal excretion data were assessed by non-parametric chi-square test. Better weight gain and feed conversion were observed in groups fed lactulosis with or without challenge of S. Typhimurium up to 21 days of age. Reduced duodenum villous height was verified on the 14th day in groups challenged with the pathogen. Reduction of S. Typhimurium fecal excretion was verified in broilers fed lactulosis from the first day of life on and 48 hours before receiving S. Typhimurium directly into the crop. Lactulosis increases broiler performance up to one week after its inoculation, influences duodenum villous height and reduces the fecal excretion of Salmonella Typhimurium.

  4. Live Attenuated Human Salmonella Vaccine Candidates: tracking the pathogen in natural infection and stimulation of host immunity

    Science.gov (United States)

    Galen, James E.; Buskirk, Amanda D.; Tennant, Sharon M.; Pasetti, Marcela F.

    2016-01-01

    Salmonellosis, caused by members of the genus Salmonella, is responsible for considerable global morbidity and mortality, in both animals and humans. In this review, we will discuss the pathogenesis of S. Typhi and S. Typhimurium, focusing on human Salmonella infections. We will trace the path of Salmonella through the body, including host entry sites, tissues and organs affected, and mechanisms involved in both pathogenesis and stimulation of host immunity. Careful consideration of the natural progression of disease provides an important context in which attenuated live oral vaccines can be rationally designed and developed. With this in mind, we will describe a series of attenuated live oral vaccines that have been successfully tested in clinical trials and demonstrated to be both safe and highly immunogenic. The attenuation strategies summarized in this review offer important insights into further development of attenuated vaccines against other Salmonella for which live oral candidates are currently unavailable. PMID:27809955

  5. Studies on the interaction between Salmonella enterica ser. Typhimurium and intestinal helminths in pigs

    DEFF Research Database (Denmark)

    Steenhard, N.R.; Roepstorff, A.; Baggesen, Dorte Lau

    2006-01-01

    trickle infected with low or moderate dose levels of Oesophagostomum spp. and challenge infected with S. Typhimurium. In another experiment, pigs were inoculated with S. Typhimurium followed by a challenge exposure to either Oesophagostomum, Trichuris or Ascaris. Enhancement of the Salmonella infection......Concomitant infections with helminths and bacteria may affect the course and the resulting disease outcome of the individual infections. Salmonella, Oesophagostomum, Trichuris and Ascaris coexist naturally in pig herds in Denmark, and possible interactions were studied. Pigs in one experiment were...... was not demonstrated in either experiment. The helminth effect on the pigs was modest and may explain the lack of influence on the Salmonella infection. A previous experiment with a larger Oesophagostomum infection level resulted in enhancement of the S. Typhimurium infection. A dose dependency of the interaction...

  6. Plasma-treated polyethylene film: A smart material applied for Salmonella Typhimurium detection

    Energy Technology Data Exchange (ETDEWEB)

    Peng-Ubol, Triranat [Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Rd, Phayathai, Bangkok 10400 (Thailand); Phinyocheep, Pranee, E-mail: scppo@mahidol.ac.th [Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Rd, Phayathai, Bangkok 10400 (Thailand); Daniel, Philippe [Laboratoire de Physique de l' Etat Condense (LPEC-UMR CNRS 6087), Universite du Maine, Avenue Olivier Messiaen, 72085, Le Mans Cedex 9 (France); Panbangred, Watanalai [Department of Biotechnology and Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology (MU-OU: CRC), Faculty of Science, Mahidol University, Rama 6 Rd, Phayathai, Bangkok 10400 (Thailand); Pilard, Jean-Francois [Unite de Chimie Organique Moleculaire et Macromoleculaire (UCO2M-UMR CNRS 6011), Universite du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9 (France); Thouand, Gerald; Durand-Thouand, Marie-Jose [Genie des Procedes Environnement et Agroalimentaire (GEPEA UMR CNRS 6144), Departement Genie Biologique, IUT de la Roche/Yon, Universite de Nantes, 18 Bd G. Defferre, 85035 La Roche sur Yon (France)

    2012-12-01

    Salmonella is a major cause of foodborne illness worldwide and is not allowed to be present in any food in all countries. The purpose of this study is to develop a simple alternative method for the detection of Salmonella based on functionalized polyethylene (PE) surfaces. Salmonella Typhimurium was used as a model bacterium. PE film was treated using dielectric plasma in order to alter the wettability of the PE surface and consequently introduce functionality on the surface. The PE film characterized by ATR-FTIR spectroscopy revealed the presence of C=O stretching of ketones, aldehydes and carboxylic acids. The antibodies against O or H antigens of Salmonella and S. Typhimurium were then respectively immobilized on the PE surface after activation of the carboxylic group using NHS/EDC followed by protein A. The evidences from ATR-FTIR, scanning electron microscopy and optical microscopy showed the presence of S. Typhimurium attached to the plasma treated PE surfaces via the two types of anti-Salmonella antibody. The plasma treated PE film developed is simple and allows efficient association of bacterial cells on the treated surfaces without the necessity of time-consuming centrifugation and washing steps for isolation of the cells. This material is considered to be a smart material applicable for S. Typhimurium detection. Highlights: Black-Right-Pointing-Pointer We developed a functionalized polyethylene film for bacterial detection. Black-Right-Pointing-Pointer We modified the surface of polyethylene film by plasma treatment. Black-Right-Pointing-Pointer ATR-FTIR spectroscopy was used to analyze the functionality on the PE surface. Black-Right-Pointing-Pointer We introduced Salmonella Typhimurium on the modified PE film. Black-Right-Pointing-Pointer SEM revealed the presence of S. Typhimurium on the plasma treated PE film.

  7. Intestinal autophagy activity is essential for host defense against Salmonella typhimurium infection in Caenorhabditis elegans.

    Science.gov (United States)

    Curt, Alexander; Zhang, Jiuli; Minnerly, Justin; Jia, Kailiang

    2014-08-01

    Salmonella typhimurium infects both intestinal epithelial cells and macrophages. Autophagy is a lysosomal degradation pathway that is present in all eukaryotes. Autophagy has been reported to limit the Salmonella replication in Caenorhabditis elegans and in mammals. However, it is unknown whether intestinal autophagy activity plays a role in host defense against Salmonella infection in C. elegans. In this study, we inhibited the autophagy gene bec-1 in different C. elegans tissues and examined the survival of these animals following Salmonella infection. Here we show that inhibition of the bec-1 gene in the intestine but not in other tissues confers susceptibility to Salmonella infection, which is consistent with recent studies in mice showing that autophagy is involved in clearance of Salmonella in the intestinal epithelial cells. Therefore, the intestinal autophagy activity is essential for host defense against Salmonella infection from C. elegans to mice, perhaps also in humans.

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

    Science.gov (United States)

    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 cells (P cells at 14 dpi (P cells (P cells (P Salmonella Typhimurium in comparison with Salmonella Typhimurium challenge alone. β-1,3/1,6-Glucan addition had significant inhibitory effects (P 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 Salmonella Typhimurium-infected birds in comparison with the PC group. Our results indicate that dietary β-1,3/1,6-glucan can alleviate intestinal mucosal barrier impairment in broiler chickens challenged with Salmonella Typhimurium.

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

    Science.gov (United States)

    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.

  10. Phytogenic feed additives in piglets challenged with Salmonella Typhimurium

    Directory of Open Access Journals (Sweden)

    Daniel Gonçalves Bruno

    2013-02-01

    Full Text Available The effects of phytogenic feed additives on piglet performance and fecal score (FDD, as well as on lipid oxidation of pork meat were evaluated. One hundred and twenty crossbred weaned piglets were randomly assigned to six treatments according to a 2 × 3 factorial design with five replicates per treatment. Factors were: challenge with Salmonella Typhimurium at 35 days of age or no challenge, and three different additives (control (CTR, basal diet; phytogenic feed additives (PHY, basal diet plus 2000 ppm of phytogenic feed additives - Rosmarinus officinalis, Mentha piperita, Lippia sidoides and Porophyllum ruderale; and antimicrobial agent (ATB, basal diet plus 100 ppm of tylosin, 2000 ppm of zinc and colistin sulfate, 30 ppm in the pre-starter basal diet, 10 ppm in the starter basal diet I and II, and 5 ppm in growth and finishing basal diet. Body weight (BW of the piglets of ATB was greater throughout the experimental period, without any differences detected between CTR and PHY. Nevertheless, from 96 to 106 days of age, the BW of the CTR group was greater than PHY. From 21 to 34 days of age, feed conversion of ATB was lower than CTR; however, PHY showed an intermediate result, which did not differ from either ATB or CTR. Challenged animals reduced feed intake from day 35 to 48 compared with unchallenged animals. Piglet performance and fecal score from 21 to 48 days of age were lower in piglets that received ATB compared with the other treatments. However, from 35 to 48 days of age, the FDD of PHY was lower than CTR. Lipid oxidation was not reduced in treated animals. Antimicrobial agent improved the growth performance of piglets until 63 days of age, and no difference was observed between the treatments from 64 to 131 days of age. Antimicrobial agent reduced FDD; the FDD of PHY was similar to that of ATB after 48 days. None of the treatments affected lipid oxidation of pork meat.

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

    Directory of Open Access Journals (Sweden)

    Jacqueline Boldrin de Paiva

    2011-12-01

    Full Text Available 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 B12 in 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.

  12. Molecular characterization of antibiotic resistant Salmonella Typhimurium and Salmonella Kentucky isolated from pre- and post-chill whole broilers carcasses.

    Science.gov (United States)

    Mohamed, Tagelsir; Zhao, Shaohua; White, David G; Parveen, Salina

    2014-04-01

    There is conflicting data regarding whether commercial chilling has any effect on persistence of Salmonella serovars, including antibiotic resistant variants, on chicken carcasses. A total of 309 Salmonella Typhimurium and Salmonella Kentucky isolates recovered from pre- and post-chill whole broiler carcasses were characterized for genetic relatedness using Pulsed Field Gel Electrophoresis (PFGE) and for the presence of virulence factors (invA, pagC, spvC) by PCR and for aerobactin and colicin production by bioassays. A subset of these isolates (n = 218) displaying resistance to either sulfisoxazole and/or ceftiofur [S. Typhimurium (n = 66) and S. Kentucky (n = 152)] were further tested for the presence of associated antibiotic resistance elements (class-I integrons and blaCMY genes) by PCR. All 145 ceftiofur resistant S. Kentucky and S. Typhimurium isolates possessed blaCMY genes. Class-I integrons were only detected in 6.1% (n = 4/66) of sulfisoxazole resistant S. Typhimurium isolates. The PFGE analysis revealed the presence of genetically diverse populations within the recovered isolates but clusters were generally concordant with serotypes and antimicrobial resistance profiles. At a 100% pattern similarity index, thirty-six percent of the undistinguishable S. Typhimurium and 22% of the undistinguishable S. Kentucky isolates were recovered from the same chilling step. All isolates possessed the invA and pagC genes, but only 1.4%possessed spvC. Irrespective of the chilling step, there was a significant difference (P < 0.05) in the production of aerobactin and colicin between S. Typhimurium and S. Kentucky isolates. Taken together, these results indicate that chilling impacted the recovery of particular Salmonella clonal groups but had no effect on the presence of class-I integrons, blaCMY genes, and tested virulence factors.

  13. Use of Attenuated but Metabolically Competent Salmonella as a Probiotic To Prevent or Treat Salmonella Infection.

    Science.gov (United States)

    Sabag-Daigle, Anice; Blunk, Henry M; Gonzalez, Juan F; Steidley, Brandi L; Boyaka, Prosper N; Ahmer, Brian M M

    2016-07-01

    Salmonella enterica is among the most burdensome of foodborne disease agents. There are over 2,600 serovars that cause a range of disease manifestations ranging from enterocolitis to typhoid fever. While there are two vaccines in use in humans to protect against typhoid fever, there are none that prevent enterocolitis. If vaccines preventing enterocolitis were to be developed, they would likely protect against only one or a few serovars. In this report, we tested the hypothesis that probiotic organisms could compete for the preferred nutrient sources of Salmonella and thus prevent or treat infection. To this end, we added the fra locus, which encodes a utilization pathway for the Salmonella-specific nutrient source fructose-asparagine (F-Asn), to the probiotic bacterium Escherichia coli Nissle 1917 (Nissle) to increase its ability to compete with Salmonella in mouse models. We also tested a metabolically competent, but avirulent, Salmonella enterica serovar Typhimurium mutant for its ability to compete with wild-type Salmonella The modified Nissle strain became more virulent and less able to protect against Salmonella in some instances. On the other hand, the modified Salmonella strain was safe and effective in preventing infection with wild-type Salmonella While we tested for efficacy only against Salmonella Typhimurium, the modified Salmonella strain may be able to compete metabolically with most, if not all, Salmonella serovars, representing a novel approach to control of this pathogen.

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

    Science.gov (United States)

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

    2016-03-01

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

  15. Synergistic effect of mutations in invA and lpfC on the ability of Salmonella typhimurium to cause murine typhoid.

    Science.gov (United States)

    Bäumler, A J; Tsolis, R M; Valentine, P J; Ficht, T A; Heffron, F

    1997-06-01

    Penetration of the intestinal mucosa at areas of Peyer's patches is an important first step for Salmonella typhimurium to produce lethal systemic disease in mice. However, mutations in genes that are important for intestinal invasion result in only moderately decreased virulence of S. typhimurium for mice. Here we report that combining mutations in invA and lpfC, two genes necessary for entry into Peyer's patches, results in a much stronger attenuation of S. typhimurium than inactivation of either of these genes alone. An S. typhimurium invA lpfC mutant was 150-fold attenuated by the oral route of infection but was fully virulent when the intestine was bypassed by intraperitoneal challenge of mice. During mixed-infection experiments, the S. typhimurium invA lpfC mutant showed a strong defect in colonizing Peyer's patches and mesenteric lymph nodes. These data suggest that mutations in invA and lpfC deactivate distinct pathways for intestinal penetration and colonization of Peyer's patches. While the inv-mediated pathway is widely distributed, the lpf operon is absent from many phylogenetic groups within the genus Salmonella. To investigate how acquisition of the lpf-mediated pathway for mucosal penetration contributed to evolution of virulence, we studied the relationship between the presence of the lpf operon and the pathogenicity for mice of 18 isolates representing 14 Salmonella serotypes. Only strains possessing the lpf operon were able to cause lethal infection in mice. These data show that both the invA- and lpfC-mediated pathways of intestinal perforation are conserved in mouse virulent Salmonella serotypes.

  16. Survivability of Salmonella typhimurium L1388 and Salmonella enteritidis L1225 under stressful growth conditions

    Directory of Open Access Journals (Sweden)

    Ngwai YB

    2007-11-01

    Full Text Available In an earlier study with Salmonella typhimurium L1388 (ST and Salmonella enteritidis L1225 (SE isolated from diseased chickens, we found that SE formed more biofilm than ST on abiotic surfaces in a time-dependent manner. Since the ability of salmonellae to survive extreme environment is related to their virulence, the present study examined the survival of Salmonella typhimurium L1388 and Salmonella nteritidis L1225 under the usual stresses that salmonellae encounter during their life cycle. This is with a view to understanding the strains’ stress tolerance that could be used to explain their virulence. Incubation at 37oC for various time periods was done for: i stationary phase (SP cells at pH 2.6; ii log-phase (LP cells at pH 4.0; log-phase or stationary phase cells in broth containing iii hydrogen peroxide, iv sodium chloride and v ethanol; vi stationary phase cells in Hank’s balanced salt solution (single strength containing 10% human serum; and vii prolong stationary phase cells. Stationary phase cells were also incubated at 52oC for 15 min. Surviving cells at the various incubation times were counted on trypticase soy agar (TSA after appropriate dilution in saline and overnight incubation at 37oC. Growth iron-poor medium was determined by growing a single bacterial colony in Medium A with shaking at 37oC or 40oC for 24 h. Statistics was done by one-way analysis-of-variance (ANOVA at P = 0.05. Differences in the survival of ST and SE were insignificant (p>0.05 in acid pH at both pH 4.0 (p = 0.3783 and pH 2.6 (p = 0.4711; at high salinity for log-phase (p = 0.1416 and stationary phase (p = 0.1816 cells; in ethanol (p = 0.5984, human serum (p = 0.8139, prolonged stationary phase (p = 0.3506; and under heat (p = 0.5766. SE was significantly (p<0.05; p = 0.0031 more tolerant to oxidative-killing by hydrogen peroxide. Culturable growth of the ST and SE in an iron-poor medium A revealed insignificant differences at 37oC (p = 0.8381 but

  17. 2D proteome analysis initiates new Insights on the Salmonella Typhimurium LuxS protein

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    Vanderleyden Jos

    2009-09-01

    Full Text Available Abstract 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

  18. Active suppression of early immune response in tobacco by the human pathogen Salmonella Typhimurium.

    Directory of Open Access Journals (Sweden)

    Natali Shirron

    Full Text Available 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.

  19. Tumor-Targeting Salmonella typhimurium A1-R: An Overview.

    Science.gov (United States)

    Hoffman, Robert M

    2016-01-01

    The present chapter reviews the development of the tumor-targeting amino-acid auxotrophic strain S. typhimurium A1 and the in vivo selection and characterization of the high-tumor-targeting strain S. typhimurium A1-R. Efficacy of S. typhimurium A1-R in nude-mouse models of prostate, breast, pancreatic, and ovarian cancer, as well as sarcoma and glioma in orthotopic mouse models is described. Also reviewed is efficacy of S. typhimurium A1-R targeting of primary bone tumor and lung metastasis of high-grade osteosarcoma, breast-cancer brain metastasis, and experimental breast-cancer bone metastasis in orthotopic mouse models. The efficacy of S. typhimurium A1-R on pancreatic cancer stem cells, on pancreatic cancer in combination with anti-angiogenic agents, as well as on cervical cancer, soft-tissue sarcoma, and pancreatic cancer patient-derived orthotopic xenograft (PDOX) mouse models, is also described.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Contribution of proton-translocating proteins to the virulence of Salmonella enterica serovars Typhimurium, Gallinarum, and Dublin in chickens and mice.

    Science.gov (United States)

    Turner, A K; Barber, L Z; Wigley, P; Muhammad, S; Jones, M A; Lovell, M A; Hulme, S; Barrow, P A

    2003-06-01

    We investigated the attenuating effects of a range of respiratory chain mutations in three Salmonella serovars which might be used in the development of live vaccines. We tested mutations in nuoG, cydA, cyoA, atpB, and atpH in three serovars of Salmonella enterica: Typhimurium, Dublin, and Gallinarum. All three serovars were assessed for attenuation in their relevant virulence assays of typhoid-like infections. Serovar Typhimurium was assessed in 1-day-old chickens and the mouse. Serovar Gallinarum 9 was assessed in 3-week-old chickens, and serovar Dublin was assessed in 6-week-old mice. Our data show variation in attenuation for the nuoG, cydA, and cyoA mutations within the different serovar-host combinations. However, mutations in atpB and atpH were highly attenuating for all three serovars in the various virulence assays. Further investigation of the mutations in the atp operon showed that the bacteria were less invasive in vivo, showing reduced in vitro survival within phagocytic cells and reduced acid tolerance. We present data showing that this reduced acid tolerance is due to an inability to adapt to conditions rather than a general sensitivity to reduced pH. The data support the targeting of respiratory components for the production of live vaccines and suggest that mutations in the atp operon provide suitable candidates for broad-spectrum attenuation of a range of Salmonella serovars.

  2. Interaction between Salmonella typhimurium and phagocytic cells in pigs - Phagocytosis, oxidative burst and killing in polymorphonuclear leukocytes and monocytes

    DEFF Research Database (Denmark)

    Riber, Ulla; Lind, Peter

    1999-01-01

    Interactions between Salmonella typhimurium and peripheral blood leucocytes from healthy, Salmonella-free pigs were investigated in vitro. Both granulocytes and monocytes phagocytized FITC-labelled heat-killed Salmonella bacteria as shown by flow cytometry. Phagocytosis in whole blood and isolated...

  3. Transport of Escherichia coli, Salmonella typhimurium, and microspheres in biochar-amended soils with different textures

    Science.gov (United States)

    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...

  4. Isolation and characterization of resistant variants from Salmonella Typhimurium cell cultures treated with benzalkonium chloride

    NARCIS (Netherlands)

    Castelijn, G.A.A.; Veen, van der S.; Moezelaar, H.R.; Abee, T.; Zwietering, M.H.

    2014-01-01

    An efficient disinfection strategy within the food industry is needed to ensure food safety and prevent the spreading of foodborne pathogens such as Salmonella Typhimurium. However, several factors affect the efficiency of disinfection treatments resulting in low level exposure of the bacterial flor

  5. Modelling transfer of Salmonella Typhimurium DT104 during simulation of grinding of pork

    DEFF Research Database (Denmark)

    Møller, Cleide; Nauta, Maarten; Christensen, B. B.

    2012-01-01

    pork slices of about 200 g per slice were inoculated with 8–9 log‐units of Salmonella Typhimurium DT104 and used for building up the contamination in the grinder. Subsequently, Salmonella‐free slices were ground and collected as samples of c. 200 g minced pork. Throughout the process, representative...

  6. Complete Genome Sequence of a Myoviridae Bacteriophage Infecting Salmonella enterica Serovar Typhimurium

    Science.gov (United States)

    Paradiso, Rubina; Orsini, Massimiliano; Bolletti Censi, Sergio; Galiero, Giorgio

    2016-01-01

    The bacteriophage 118970_sal3 was isolated from water buffalo feces in southern Italy, exhibiting lytic activity against Salmonella enterica serovar Typhimurium. This bacteriophage belongs to the Myoviridae family and has a 39,464-bp double-stranded DNA (ds-DNA) genome containing 53 coding sequences (CDSs). PMID:27688333

  7. Molecular cloning of the Salmonella typhimurium lep gene in Escherichia coli

    NARCIS (Netherlands)

    van Dijl, J M; van den Bergh, R; Reversma, T; Smith, H; Bron, S; Venema, G

    1990-01-01

    A system is described which enabled the selection of a heterologous lep gene, encoding signal peptidase I, in Escherichia coli. It is based on complementation of an E. coli mutant, in which the synthesis of signal peptidase I can be regulated. With this system the lep gene of Salmonella typhimurium

  8. Tumor induction in Swiss mice by filtrable agent and Salmonella typhimurium.

    Directory of Open Access Journals (Sweden)

    Hamazaki,Yukio

    1979-10-01

    Full Text Available Combined inoculation of a cell-free extract of leukotic tissue of D103 mice and Salmonella typhimurium into adult Swiss mice induced leukosis and solid tumors. The induced solid tumors were histologically multifarious, and were transplantable in Swiss mice, but not in other strains of mice.

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

    DEFF Research Database (Denmark)

    Herrero-Fresno, Ana; Wallrodt, Inke; Leekitcharoenphon, Pimlapas;

    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 viru...

  10. Lethal Escherichia coli and Salmonella typhimurium endotoxemia is mediated through different pathways.

    NARCIS (Netherlands)

    Netea, M.G.; Kullberg, B.J.; Joosten, L.A.B.; Sprong, T.; Verschueren, C.M.M.; Boerman, O.C.; Amiot, F.; Berg, W.B. van den; Meer, J.W.M. van der

    2001-01-01

    Despite the differences in the molecular structure between lipopolysaccharides (LPS) isolated from Escherichia coli, Klebsiella pneumoniae or Salmonella typhimurium, the potential differences in their biological effects in vivo have not been investigated. In the present study, TNF and LT double knoc

  11. Risk factors for clinical Salmonella enterica subsp. enterica serovar Typhimurium infection on Dutch dairy farms

    NARCIS (Netherlands)

    Veling, J.; Wilpshaar, H.; Frankena, K.; Bartels, C.; Barkema, H.W.

    2002-01-01

    Risk factors for outbreaks in 1999 of clinical Salmonella enterica subsp. enterica serovar Typhimurium infection on dairy farms were studied in a matched case–control study with 47 case farms and 47 control farms. All 47 case farms experienced a clinical outbreak of salmonellosis which was confirmed

  12. Global Genomic Epidemiology of Salmonella enterica Serovar Typhimurium DT104

    DEFF Research Database (Denmark)

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

    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 struc...

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

    DEFF Research Database (Denmark)

    Hartman, Hassan B.; Fell, David A.; Rossell, Sergio;

    2014-01-01

    . 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...

  14. Epidemiological characteristics of Salmonella Typhimurium isolated from animals and feed in Poland

    DEFF Research Database (Denmark)

    Wasyl, D.; Sandvang, D.; Skov, M. N.;

    2006-01-01

    Fifty-seven Salmonella Typhimurium strains isolated from poultry, swine and animal feed in Poland during the years 1979-1998 and 2000-2002 were analysed with conventional and molecular techniques. Antimicrobial resistance as well as multiresistance was found, respectively, in 80.1 % and 56...

  15. Escherichia coli and Salmonella typhimurium supX genes specify deoxyribonucleic acid topoisomerase I.

    OpenAIRE

    Trucksis, M; Golub, E I; Zabel, D J; Depew, R E

    1981-01-01

    Mutations of the Escherichia coli or Salmonella typhimurium supX genes eliminated deoxyribonucleic acid topoisomerase I. Suppression of a supX amber mutation partially restored the topoisomerase. Multicopy plasmids carrying supX+ caused overproduction of topoisomerase. Thus, these supX genes were identified as topA genes which specify deoxyribonucleic acid topoisomerase I.

  16. Using a Surface Plasmon Resonance Biosensor for Rapid Detection of Salmonella Typhimurium in Chicken Carcass

    Institute of Scientific and Technical Information of China (English)

    Yu-bin Lan; Shi-zhou Wang; Yong-guang Yin; W.Clint Hoffmann; Xiao-zhe Zheng

    2008-01-01

    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 Spreeta biosensor kits were used to detect Salmonella Typhimurium on chicken carcass successfully. A taste sensor like electronic tongue or biosensors was used to basically "taste" the object and differentiated one object from the other with different taste sensor signatures. The surface plasmon resonance biosensor has potential for use in rapid, real-time detection and identification of bacteria, and to study the interaction of organisms with different antisera or other molecular species. The selectivity of the SPR biosensor was assayed using a series of antibody concentrations and dilution series of the organism. The SPR biosensor showed promising to detect the existence of Salmonella Typhimurium at 1×106 CFU/ml. Initial results show that the SPR biosensor has the potential for its application in pathogenic bacteria monitoring. However, more tests need to be done to confirm the detection limitation.

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

    Science.gov (United States)

    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.

  18. .Analysis of the contribution of bacteriophage ST64B to in vitro virulence traits of Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

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

    2014-03-01

    Comparison of the publicly available genomes of the virulent Salmonella enterica serovar Typhimurium (S. Typhimurium) strains SL1344, 14028s and D23580 to that of the virulence-attenuated isolate LT2 revealed the absence of a full sequence of bacteriophage ST64B in the latter. Four selected ST64B regions of unknown function (sb7-sb11, sb46, sb49-sb50 and sb54) were mapped by PCR in two strain collections: (i) 310 isolates of S. Typhimurium from human blood or stool samples, and from food, animal and environmental reservoirs; and (ii) 90 isolates belonging to other serovars. The region sb49-sb50 was found to be unique to S. Typhimurium and was strongly associated with strains isolated from blood samples (100  and 28.4 % of the blood and non-blood isolates, respectively). The region was cloned into LT2 and knocked out in SL1344, and these strains were compared to wild-type isogenic strains in in vitro assays used to predict virulence association. No difference in invasion of the Int407 human cell line was observed between the wild-type and mutated strains, but the isolate carrying the whole ST64B prophage was found to have a slightly better survival in blood. The study showed a high prevalence and a strong association between the prophage ST64B and isolates of S. Typhimurium collected from blood, and may indicate that such strains constitute a selected subpopulation within this serovar. Further studies are indicated to determine whether the slight increase in blood survival observed in the strain carrying ST64B genes is of paramount importance for systemic infections.

  19. Structure of the ribosomal interacting GTPase YjeQ from the enterobacterial species Salmonella typhimurium

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, C. E. [Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Johnson, C.; Lamb, H. K. [Institute of Cell and Molecular Biosciences, Catherine Cookson Building, Medical School, Framlington Place, Newcastle University, Newcastle-upon-Tyne NE2 4HH (United Kingdom); Lockyer, M. [Arrow Therapeutics Ltd, Britannia House, Trinity Street, Borough, London SE1 1DA (United Kingdom); Charles, I. G. [The Wolfson Institute for Biomedical Research, The Cruciform Building, University College London, Gower Street, London WC1E 6BT (United Kingdom); Hawkins, A. R. [Institute of Cell and Molecular Biosciences, Catherine Cookson Building, Medical School, Framlington Place, Newcastle University, Newcastle-upon-Tyne NE2 4HH (United Kingdom); Stammers, D. K., E-mail: daves@strubi.ox.ac.uk [Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom)

    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.

  20. Enhancement of host immune responses by oral vaccination to Salmonella enterica serovar Typhimurium harboring both FliC and FljB flagella.

    Directory of Open Access Journals (Sweden)

    Jeong Seon Eom

    Full Text Available Flagellin, the structural component of the flagellar filament in various motile bacteria, can contribute to the activation of NF-κB and proinflammatory cytokine expression during the innate immune response in host cells. Thus, flagellin proteins represent a particularly attractive target for the development of vaccine candidates. In this study, we investigated the immune response by increasing the flagella number in the iacP mutant strain and the adjuvant activity of the flagellin component FljB of Salmonella enterica serovar Typhimurium. We found that the iacP mutant strain expresses two flagellin proteins (FliC and FljB, which result in increased NF-κB-dependent gene expression in bone marrow derived macrophages. Using an oral immunization mouse model, we observed that the administration of a live attenuated S. typhimurium BRD509 strain expressing the FliC and FljB flagellins induced significantly enhanced flagellin-specific IgG responses in the systemic compartment. The mice immunized with the recombinant attenuated S. typhimurium strain that has two types of flagella were protected from lethal challenge with the Salmonella SL1344 strain. These results indicate that overexpression of flagella in the iacP mutant strain enhance the induction of an antigen-specific immune responses in macrophage cell, and both the FliC and FljB flagellar filament proteins-producing S. typhimurium can induce protective immune responses against salmonellosis.

  1. An outbreak of multidrug-resistant, quinolone-resistant Salmonella enterica serotype typhimurium DT104

    DEFF Research Database (Denmark)

    Molbak, K.; Baggesen, Dorte Lau; Aarestrup, Frank Møller

    1999-01-01

    Background Food-borne salmonella infections have become a major problem in industrialized countries. The strain of Salmonella enterica serotype typhimurium known as definitive phage type 104 (DT104) is usually resistant to five drugs: ampicillin, chloramphenicol, streptomycin, sulfonamides...... findings here. Results Until 1997, DT104 infections made up less than 1 percent of all human salmonella infections. The strain isolated from patients in the first community outbreak of DT104 in Denmark, in 1998, was resistant to nalidixic acid and had reduced susceptibility to fluoroquinolones...

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

    Institute of Scientific and Technical Information of China (English)

    Doaa M Abd El-Aziz

    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.

  3. Inactivation of Salmonella enterica serovar Typhimurium on fresh produce by cold atmospheric gas plasma technology.

    Science.gov (United States)

    Fernández, A; Noriega, E; Thompson, A

    2013-02-01

    Cold atmospheric gas plasma treatment (CAP) is an alternative approach for the decontamination of fresh and minimally processed food. In this study, the effects of growth phase, growth temperature and chemical treatment regime on the inactivation of Salmonella enterica serovar Typhimurium (S. Typhimurium) by Nitrogen CAP were examined. Furthermore, the efficacy of CAP treatment for decontaminating lettuce and strawberry surfaces and potato tissue inoculated with S. Typhimurium was evaluated. It was found that the rate of inactivation of S. Typhimurium was independent of the growth phase, growth temperature and chemical treatment regime. Under optimal conditions, a 2 min treatment resulted in a 2.71 log-reduction of S. Typhimurium viability on membrane filters whereas a 15 min treatment was necessary to achieve 2.72, 1.76 and 0.94 log-reductions of viability on lettuce, strawberry and potato, respectively. We suggest that the differing efficiency of CAP treatment on the inactivation of S. Typhimurium on these different types of fresh foods is a consequence of their surface features. Scanning electron microscopy of the surface structures of contaminated samples of lettuce, strawberry and potato revealed topographical features whereby S. Typhimurium cells could be protected from the active species generated by plasma.

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

    DEFF Research Database (Denmark)

    Birk, Tina; Henriksen, Sidsel; Müller, K.;

    2016-01-01

    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 72 h sausage fermentation at 25 °C. After 0, 7 and > 35 d of frozen storage, sausage batters were prepared with NaCl (3%) and NaNO2 (0, 100 ppm) 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...

  5. Salmonella typhimurium infection increases p53 acetylation in intestinal epithelial cells.

    Science.gov (United States)

    Wu, Shaoping; Ye, Zhongde; Liu, Xingyin; Zhao, Yun; Xia, Yinglin; Steiner, Andrew; Petrof, Elaine O; Claud, Erika C; Sun, Jun

    2010-05-01

    The ability of Salmonella typhimurium to enter intestinal epithelial cells constitutes a crucial step in pathogenesis. Salmonella invasion of the intestinal epithelium requires bacterial type three secretion system. Type three secretion system is a transport device that injects virulence proteins, called effectors, to paralyze or reprogram the eukaryotic cells. Avirulence factor for Salmonella (AvrA) is a Salmonella effector that inhibits the host's inflammatory responses. The mechanism by which AvrA modulates host cell signaling is not entirely clear. p53 is situated at the crossroads of a network of signaling pathways that are essential for genotoxic and nongenotoxic stress responses. We hypothesized that Salmonella infection activates the p53 pathway. We demonstrated that Salmonella infection increased p53 acetylation. Cells infected with AvrA-sufficient Salmonella have increased p53 acetylation, whereas cells infected with AvrA-deficient Salmonella have less p53 acetylation. In a cell-free system, AvrA possessed acetyltransferase activity and used p53 as a substrate. AvrA expression increased p53 transcriptional activity and induced cell cycle arrest. HCT116 p53-/- cells had less inflammatory responses. In a mouse model of Salmonella infection, intestinal epithelial p53 acetylation was increased by AvrA expression. Our studies provide novel mechanistic evidence that Salmonella modulates the p53 pathway during intestinal inflammation and infection.

  6. Expression of STM4467-encoded arginine deiminase controlled by the STM4463 regulator contributes to Salmonella enterica serovar Typhimurium virulence.

    Science.gov (United States)

    Choi, Younho; Choi, Jeongjoon; Groisman, Eduardo A; Kang, Dong-Hyun; Shin, Dongwoo; Ryu, Sangryeol

    2012-12-01

    Arginine deiminase (ADI), carbamate kinase (CK), and ornithine transcarbamoylase (OTC) constitute the ADI system. In addition to metabolic functions, the ADI system has been implicated in the virulence of certain pathogens. The pathogenic intracellular bacterium Salmonella enterica serovar Typhimurium possesses the STM4467, STM4466, and STM4465 genes, which are predicted to encode ADI, CK, and OTC, respectively. Here we report that the STM4467 gene encodes an ADI and that ADI activity plays a role in the successful infection of a mammalian host by S. Typhimurium. An STM4467 deletion mutant was defective for replication inside murine macrophages and was attenuated for virulence in mice. We determined that a regulatory protein encoded by the STM4463 gene functions as an activator for STM4467 expression. The expression of the ADI pathway genes was enhanced inside macrophages in a process that required STM4463. Lack of STM4463 impaired the ability of S. Typhimurium to replicate within macrophages. A mutant defective in STM4467-encoded ADI displayed normal production of nitric oxide by macrophages.

  7. A murine model to study the antibacterial effect of copper on infectivity of Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Robert H. Reed

    2010-12-01

    Full Text Available 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.

  9. Invasive African Salmonella Typhimurium induces bactericidal antibodies against O-antigens.

    Science.gov (United States)

    Rondini, Simona; Lanzilao, Luisa; Necchi, Francesca; O'Shaughnessy, Colette M; Micoli, Francesca; Saul, Allan; MacLennan, Calman A

    2013-10-01

    Nontyphoidal Salmonella are a major and emerging cause of fatal invasive disease in Africa, and are genetically distinct from those found elsewhere in the world. Understanding the targets of protective immunity to these African Salmonellae is key to vaccine development. We immunized mice and rabbits with heat-inactivated wild-type African invasive Salmonella Typhimurium D23580 and rough mutants lacking O-antigen. Wild-type Salmonella, unlike rough bacteria, induced a large bactericidal antibody response mainly against O-antigen. Bactericidal ability of anti-O-antigen antibodies was confirmed following purification by affinity chromatography. The current findings support the development of an O-antigen conjugate vaccine against invasive nontyphoidal Salmonellae for Africa.

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

    Science.gov (United States)

    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

    2014-02-01

    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 (10(6) 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.

  11. A questionnaire-based, retrospective field study of persistence of Salmonella Enteritidis and Salmonella Typhimurium in Danish broiler houses

    DEFF Research Database (Denmark)

    Gradel, K.O.; Rattenborg, Erik

    2003-01-01

    A questionnaire-based, retrospective field study was conducted in 78 Danish broiler houses (analytical units) on 42 farms. In spring 1997, all these broiler houses had been infected with Salmonella Enteritidis, phage type 8, and/or Salmonella Typhimurium, definitive-type 66, by day-old chicks del...... soap and water for washing hands in the anteroom, hygiene barriers when removing dead broilers, gravel alongside the broiler house, systematic checks of indoor rodent-bait depots, and combined surface and pulse-fogging disinfection....

  12. Coptidis rhizome and Si Jun Zi Tang can prevent Salmonella enterica serovar Typhimurium infection in mice.

    Science.gov (United States)

    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.

  13. Coptidis rhizome and Si Jun Zi Tang can prevent Salmonella enterica serovar Typhimurium infection in mice.

    Directory of Open Access Journals (Sweden)

    Chiung-Hung Chang

    Full Text Available 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.

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

    Science.gov (United States)

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

    2014-10-03

    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.

  15. A quantitative analysis of Salmonella Typhimurium metabolism during infection

    OpenAIRE

    Steeb, Benjamin

    2012-01-01

    In this thesis, Salmonella metabolism during infection was investigated. The goal was to gain a quantitative and comprehensive understanding of Salmonella in vivo nutrient supply, utilization and growth. To achieve this goal, we used a combined experimental / in silico approach. First, we generated a reconstruction of Salmonella metabolism ([1], see 2.1). This reconstruction was then combined with in vivo data from experimental mutant phenotypes to build a comprehensive quantitative in viv...

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

    OpenAIRE

    Arsenault, Ryan J.; Napper, Scott; Kogut, Michael H.

    2013-01-01

    Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) infection of chickens that are more than a few days old results in asymptomatic cecal colonization with persistent shedding of bacteria. We hypothesized that while the bacterium colonizes and persists locally in the cecum it has systemic effects, including changes to metabolic pathways of skeletal muscle, influencing the physiology of the avian host. Using species-specific peptide arrays to perform kinome analysis on metabolic s...

  17. Quantitative proteomics and bioinformatic analysis provide new insight into the dynamic response of porcine intestine to Salmonella Typhimurium

    DEFF Research Database (Denmark)

    Collado-Romero, Melanie; Aguilar, Carmen; Arce, Cristina;

    2015-01-01

    The enteropathogen Salmonella Typhimurium (S. Typhimurium) is the most commonly non-typhoideal serotype isolated in pig worldwide. Currently, one of the main sources of human infection is by consumption of pork meat. Therefore, prevention and control of salmonellosis in pigs is crucial for minimi...

  18. Complete, closed genome sequences of 10 Salmonella enterica subsp. enterica serovar Typhimurium strains isolated from human and bovine sources

    Science.gov (United States)

    Salmonella enterica are a leading cause of enterocolitis for humans and animals. S. enterica serovar Typhimurium infects a broad range of hosts. To facilitate genomic comparisons among isolates from different sources, we present the complete genome sequences of ten S. Typhimurium strains, five each...

  19. Distribution of prophages and SGI-1 antibiotic-resistance genes among different Salmonella enterica serovar Typhimurium isolates

    NARCIS (Netherlands)

    Hermans, A.P.H.M.; Beuling, A.M.; Hoek, van A.H.A.M.; Aarts, H.J.M.; Abee, T.; Zwietering, M.H.

    2006-01-01

    Recently, the authors identified Salmonella enterica serovar Typhimurium (S. Typhimurium) definitive type (DT)104-specific sequences of mainly prophage origin by genomic subtractive hybridization. In the present study, the distribution of the prophages identified, ST104 and ST64B, and the novel prop

  20. Quantification of contamination of lettuce by GFP-expressing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium

    NARCIS (Netherlands)

    Franz, Eelco; Visser, Anna A; Van Diepeningen, Anne D; Klerks, Michel M; Termorshuizen, Aad J; van Bruggen, Ariena H C

    2007-01-01

    The primary objective of this study was to determine the possibility of internalization of GFP-expressing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium (S. Typhimurium) strains MAE 110 (multi-cellular morphology) and 119 (wild type morphology) into lettuce seedlings (Lactuca s

  1. Draft Genome Sequences of 40 Salmonella enterica Serovar Typhimurium Strains Isolated from Humans and Food in Brazil

    Science.gov (United States)

    Almeida, Fernanda; Medeiros, Marta Inês Cazentini; Rodrigues, Dália Prazeres; Payne, Justin; Timme, Ruth E.

    2016-01-01

    Salmonellosis is an important health problem worldwide and Salmonella enterica serovar Typhimurium is one of the most common isolated serovars. Here, we reported the draft genomes of 40 S. Typhimurium strains isolated from humans and food in Brazil. These draft genomes will improve phylogenetic analysis and will help enhance our understanding of strains of this serovar isolated in Brazil. PMID:27660768

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

    Science.gov (United States)

    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.

  3. Multistate outbreak of human Salmonella typhimurium infections associated with aquatic frogs - United States, 2009.

    Science.gov (United States)

    2010-01-08

    During April-July 2009, the Utah Department of Health identified five cases of Salmonella Typhimurium infection with indistinguishable pulsed-field gel electrophoresis (PFGE) patterns, predominantly among children. In August, CDC began a multistate outbreak investigation to determine the source of the infections. This report summarizes the results of this ongoing investigation, which, as of December 30, had identified 85 S. Typhimurium human isolates with the outbreak strain from 31 states. In a multistate case-control study, exposure to frogs was found to be significantly associated with illness (63% of cases versus 3% of controls; matched odds ratio [mOR] = 24.4). Among 14 case-patients who knew the type of frog, all had exposure to an exclusively aquatic frog species, the African dwarf frog. Environmental samples from aquariums containing aquatic frogs in four homes of case-patients yielded S. Typhimurium isolates matching the outbreak strain. Preliminary traceback information has indicated these frogs likely came from the same breeder in California. Reptiles (e.g., turtles) and amphibians (e.g., frogs) have long been recognized as Salmonella carriers, and three multistate outbreaks of human Salmonella infections associated with turtle contact have occurred since 2006. However, this is the first reported multistate outbreak of Salmonella infections associated with amphibians. Educational materials aimed at preventing salmonellosis from contact with reptiles should be expanded to include amphibians, such as aquatic frogs.

  4. Constraint-based analysis of metabolic capacity of Salmonella typhimurium during host-pathogen interaction

    Directory of Open Access Journals (Sweden)

    Palsson Bernhard

    2009-04-01

    Full Text Available Abstract Background Infections with Salmonella cause significant morbidity and mortality worldwide. Replication of Salmonella typhimurium inside its host cell is a model system for studying the pathogenesis of intracellular bacterial infections. Genome-scale modeling of bacterial metabolic networks provides a powerful tool to identify and analyze pathways required for successful intracellular replication during host-pathogen interaction. Results We have developed and validated a genome-scale metabolic network of Salmonella typhimurium LT2 (iRR1083. This model accounts for 1,083 genes that encode proteins catalyzing 1,087 unique metabolic and transport reactions in the bacterium. We employed flux balance analysis and in silico gene essentiality analysis to investigate growth under a wide range of conditions that mimic in vitro and host cell environments. Gene expression profiling of S. typhimurium isolated from macrophage cell lines was used to constrain the model to predict metabolic pathways that are likely to be operational during infection. Conclusion Our analysis suggests that there is a robust minimal set of metabolic pathways that is required for successful replication of Salmonella inside the host cell. This model also serves as platform for the integration of high-throughput data. Its computational power allows identification of networked metabolic pathways and generation of hypotheses about metabolism during infection, which might be used for the rational design of novel antibiotics or vaccine strains.

  5. Specific Monoclonal Antibody Overcomes the Salmonella enterica Serovar Typhimurium's Adaptive Mechanisms of Intramacrophage Survival and Replication.

    Directory of Open Access Journals (Sweden)

    Swarmistha Devi Aribam

    Full Text Available Salmonella-specific antibodies play an important role in host immunity; however, the mechanisms of Salmonella clearance by pathogen-specific antibodies remain to be completely elucidated since previous studies on antibody-mediated protection have yielded inconsistent results. These inconsistencies are at least partially attributable to the use of polyclonal antibodies against Salmonella antigens. Here, we developed a new monoclonal antibody (mAb-449 and identified its related immunogen that protected BALB/c mice from infection with Salmonella enterica serovar Typhimurium. In addition, these data indicate that the mAb-449 immunogen is likely a major protective antigen. Using in vitro infection studies, we also analyzed the mechanism by which mAb-449 conferred host protection. Notably, macrophages infected with mAb-449-treated S. Typhimurium showed enhanced pathogen uptake compared to counterparts infected with control IgG-treated bacteria. Moreover, these macrophages produced elevated levels of pro-inflammatory cytokine TNFα and nitric oxide, indicating that mAb-449 enhanced macrophage activation. Finally, the number of intracellular bacteria in mAb-449-activated macrophages decreased considerably, while the opposite was found in IgG-treated controls. Based on these findings, we suggest that, although S. Typhimurium has the potential to survive and replicate within macrophages, host production of a specific antibody can effectively mediate macrophage activation for clearance of intracellular bacteria.

  6. Coated fatty acids alter virulence properties of Salmonella Typhimurium and decrease intestinal colonization of pigs.

    Science.gov (United States)

    Boyen, F; Haesebrouck, F; Vanparys, A; Volf, J; Mahu, M; Van Immerseel, F; Rychlik, I; Dewulf, J; Ducatelle, R; Pasmans, F

    2008-12-10

    Salmonella Typhimurium infections in pigs are a major source of human foodborne salmonellosis. To reduce the number of infected pigs, acidification of feed or drinking water is a common practice. The aim of the present study was to determine whether some frequently used short- (SCFA) and medium-chain fatty acids (MCFA) are able to alter virulence gene expression and to decrease Salmonella Typhimurium colonization and shedding in pigs using well established and controlled in vitro and in vivo assays. Minimal inhibitory concentrations (MIC) of 4 SCFA (formic acid, acetic acid, propionic acid and butyric acid) and 2 MCFA (caproic and caprylic acid) were determined using 54 porcine Salmonella Typhimurium field strains. MIC values increased at increasing pH-values and were two to eight times lower for MCFA than for SCFA. Expression of virulence gene fimA was significantly lower when bacteria were grown in LB-broth supplemented with sub-MIC concentrations of caproic or caprylic acid (2 mM). Expression of hilA and invasion in porcine intestinal epithelial cells was significantly lower when bacteria were grown in LB-broth containing sub-MIC concentrations of butyric acid or propionic acid (10 mM) and caproic or caprylic acid (2 mM). When given as feed supplement to pigs experimentally infected with Salmonella Typhimurium, coated butyric acid decreased the levels of faecal shedding and intestinal colonization, but had no influence on the colonization of tonsils, spleen and liver. Uncoated fatty acids, however, did not influence fecal shedding, intestinal or tonsillar colonization in pigs. In conclusion, supplementing feed with certain coated fatty acids, such as butyric acid, may help to reduce the Salmonella load in pigs.

  7. Receptor diversity and host interaction of bacteriophages infecting Salmonella enterica serovar Typhimurium.

    Directory of Open Access Journals (Sweden)

    Hakdong Shin

    Full Text Available BACKGROUND: Salmonella enterica subspecies enterica serovar Typhimurium is a gram-negative pathogen causing salmonellosis. Salmonella Typhimurium-targeting bacteriophages have been proposed as an alternative biocontrol agent to antibiotics. To further understand infection and interaction mechanisms between the host strains and the bacteriophages, the receptor diversity of these phages needs to be elucidated. METHODOLOGY/PRINCIPAL FINDINGS: Twenty-five Salmonella phages were isolated and their receptors were identified by screening a Tn5 random mutant library of S. Typhimurium SL1344. Among them, three types of receptors were identified flagella (11 phages, vitamin B(12 uptake outer membrane protein, BtuB (7 phages and lipopolysaccharide-related O-antigen (7 phages. TEM observation revealed that the phages using flagella (group F or BtuB (group B as a receptor belong to Siphoviridae family, and the phages using O-antigen of LPS as a receptor (group L belong to Podoviridae family. Interestingly, while some of group F phages (F-I target FliC host receptor, others (F-II target both FliC and FljB receptors, suggesting that two subgroups are present in group F phages. Cross-resistance assay of group B and L revealed that group L phages could not infect group B phage-resistant strains and reversely group B phages could not infect group L SPN9TCW-resistant strain. CONCLUSIONS/SIGNIFICANCE: In this report, three receptor groups of 25 newly isolated S. Typhimurium-targeting phages were determined. Among them, two subgroups of group F phages interact with their host receptors in different manner. In addition, the host receptors of group B or group L SPN9TCW phages hinder other group phage infection, probably due to interaction between receptors of their groups. This study provides novel insights into phage-host receptor interaction for Salmonella phages and will inform development of optimal phage therapy for protection against Salmonella.

  8. DETERMINACIÓN DE Salmonella Typhimurium EN COMPOST INOCULADO ARTIFICIALMENTE EMPLEADO EN UN CULTIVO DE LECHUGA Salmonella Typhimurium determination in compost artificially inoculated in a lettuce crop

    Directory of Open Access Journals (Sweden)

    DIANA MARCELA RODRÍGUEZ

    Full Text Available Salmonella enterica serovariedad Typhimurium, se ha asociado a brotes por el consumo de frutas y vegetales contaminadas a partir de agua de riego, manipuladores, bioabono y suelo. En esta investigación se inoculó artificialmente un bioabono aplicado a un cultivo de lechuga para determinar la capacidad de transferencia a las plantas, así como establecer el efecto del uso de cubiertas de polietileno en la protección del cultivo frente a este patógeno. Para ello, se utilizaron plántulas de lechuga de ocho semanas y se establecieron cuatro tratamientos y dos controles: T1 y T2, con y sin cubierta de polietileno respectivamente, contenían una concentración de Salmonella enterica Serovariedad Typhimurium ATCC 13176 inoculada en el compost en concentración de 0,04 mo/g, T3 y T4 con y sin cubierta de polietileno respectivamente con 100 mo/g de compost y finalmente C1 y C2 con y sin cubierta pero sin inoculación. El seguimiento del microorganismo en suelo se realizó durante las ocho semanas del cultivo, mediante la técnica de NMP/4 g (EPA, 2006 al cabo de este tiempo se evaluó el total de plantas cultivadas mediante la misma técnica. Se determinó que Salmonella enterica serovariedad Typhimurium ATCC 13176 se transmite a la lechuga, a partir del bioabono contaminado (OR=2,53 sin importar la concentración inicial del microorganismo en el bioabono; así mismo se encontró que existe asociación entre la contaminación y la condición de cubierta del cultivo (p=0,002. Por otra parte, al analizar las raíces no se encontró asociación de transmisión.Salmonella enterica serovariedad Typhimurium, has been associated with outbreaks because of the ingestion of fruits and vegetables and those outbreaks have been related due to contamination sources like irrigation water, farm workers influence and the soil itself. In this investigation it was artificially inoculated in a compost and later applied to a lettuce crop, in order to determine the

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

    Science.gov (United States)

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

    2015-11-01

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

  10. Behaviour of Salmonella Typhimurium during production and storage of artisan water buffalo mozzarella cheese

    Directory of Open Access Journals (Sweden)

    Roberto Rosmini

    2012-07-01

    Full Text Available Water buffalo mozzarella cheese (WBMC is a fresh pasta filata cheese produced from whole chilled buffalo milk. Although pasteurization of milk and the use of defined starter cultures are recommended, traditional technology involving the use of unpasteurized milk and natural whey cultures is still employed for WBMC production in Italy. The aim of this study were to assess the behaviour of Salmonella Typhimurium during the production of artisan water buffalo mozzarella cheese and during its shelf life under different temperature conditions. Raw milk was inoculated with S. Typhimurium and the evolution of S. Typhimurium count during production and shelf life was monitored. In artisan WBMC production technology S. Typhimurium multiplied in the curd during ripening, but its growth rate expressed in log CFU/g/h was lower than the growth rate reported by theoretical predictions. Stretching proved to be a process with good repeatability and able to reduce S. Typhimurium contamination by 5.5 Log CFU/g. The intrinsic characteristics of traditional WBMC proved to be unable to obstacolate the growth of S. Typhimurium during storage in the case of thermal abuse. Control of raw milk contamination and a proper refrigeration temperature are key factors in reducing the risk for consumers.

  11. Antimicrobial susceptibility and internalization of Salmonella Typhimurium in vacuum-tumbled marinated beef products.

    Science.gov (United States)

    Pokharel, S; Brooks, J C; Martin, J N; Brashears, M M

    2016-12-01

    As the incidence of multidrug resistance (MDR) Salmonella enterica serotype Typhimurium is increasing, data regarding the antimicrobial interventions and pathogen internalization in marinated meat products are important. This study evaluated the antimicrobial intervention and internalization of Salm. Typhimurium in marinated beef sirloin steaks. Beef bottom sirloin flaps (IMPS #185A; USDA Select) inoculated (10(8)  log10  CFU ml(-1) ) with Salm. Typhimurium were sprayed (lactic acid (4%) and buffered vinegar (2%)) prior to vacuum-tumbled marination (0·35% sodium chloride and 0·45% sodium tripolyphosphate) for 30 min. Pathogen presence after antimicrobial spray, vacuum-tumbled marination, and translocation was determined by direct plating on Xylose Lysine Deoxycholate (XLD) agar with tryptic soy agar (TSA) overlay. The data imply varied internalization and antimicrobial susceptibility pattern of Salm. Typhimurium in marinated meat. Lactic acid (4%) spray (P < 0·0001) and buffered vinegar (2%; P < 0·0001) reduced surface populations of Salm. Typhimurium on inoculated beef sirloin flaps prior to vacuum marination. However, lactic acid treated sirloin flaps had greater reductions (~2 log10  CFU cm(-2) ) than buffered vinegar when compared with control prior to vacuum marination. However, the translocation of Salm. Typhimurium following vacuum marination was not influenced (P < 0·333) by the application of a surface organic acid spray prior to marination.

  12. The anti-infective activity of punicalagin against Salmonella enterica subsp. enterica serovar typhimurium in mice.

    Science.gov (United States)

    Li, Guanghui; Feng, Yuqing; Xu, Yunfeng; Wu, Qian; Han, Qi'an; Liang, Xiujun; Yang, Baowei; Wang, Xin; Xia, Xiaodong

    2015-07-01

    Punicalagin, a major bioactive component of pomegranate peel, has been proven to have antioxidant, antiviral, anti-apoptosis, and hepatoprotective properties. The aim of this study was to investigate the anti-infective activity of punicalagin in a mouse model. C57BL/6 mice were initially challenged with Salmonella enterica subsp. enterica serovar typhimurium (S. typhimurium) and then treated with punicalagin. Food and water consumption and body weight were recorded daily. On day 8 post infection, the mice were sacrificed to examine pathogen counts in tissues, hematological parameters, cytokine levels, and histological changes. Compared to mice only infected with S. typhimurium, punicalagin-treated mice had more food consumption and less weight loss. A higher survival rate and lower counts of viable S. typhimurium in feces, liver, spleen, and kidney were found in the punicalagin-treated mice. The enzyme linked immunosorbent assay showed that the levels of IL-6, IL-10, and IFN-γ in serum and the spleen and TNF-α in serum, the spleen and the liver were reduced by punicalagin. Moreover, more neutrophils and higher neutrophil-to-mononuclear cell ratios in the punicalagin-treated mice were observed. Histological examination showed that punicalagin protected cells in the liver and spleen from hemorrhagic necrosis. It is concluded that punicalagin has a beneficial effect against S. typhimurium infection in mice. The anti-infective properties, together with other nutritionally beneficial effects, make punicalagin a promising supplement in human food or animal feeds to prevent disease associated with S. typhimurium.

  13. Effect of the oyster contaminated in Salmonella typhimurium and Escherichia coli; Efecto del ostion contaminado en Salmonella typhimurium y Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Brena V, M

    1992-08-15

    In this work the effect of the oyster contaminated in the species of bacteria better studied by its genetic composition these are the Salmonella typhimurium and the Escherichia coli and that its have been starting point for later radiobiological studies in superior organisms. Of this its have arisen two general lines. The research about the genotoxic effect of substances or mixtures in bacteria with the collaboration of the groups of Drosophila and X-ray Fluorescence analysis and on the other hand the study of the low doses of radiation also in bacteria. It is also treated the topic about the genetic effect of aromatic hydrocarbons in different biological systems. (Author)

  14. Modeling the inactivation of Salmonella Typhimurium, Listeria monocytogenes, and Salmonella Enteritidis on poultry products exposed to pulsed UV light.

    Science.gov (United States)

    Keklik, Nene M; Demirci, Ali; Puri, Virendra M; Heinemann, Paul H

    2012-02-01

    Pulsed UV light inactivation of Salmonella Typhimurium on unpackaged and vacuum-packaged chicken breast, Listeria monocytogenes on unpackaged and vacuum-packaged chicken frankfurters, and Salmonella Enteritidis on shell eggs was explained by log-linear and Weibull models using inactivation data from previous studies. This study demonstrated that the survival curves of Salmonella Typhimurium and L. monocytogenes were nonlinear exhibiting concavity. The Weibull model was more successful than the log-linear model in estimating the inactivations for all poultry products evaluated, except for Salmonella Enteritidis on shell eggs, for which the survival curve was sigmoidal rather than concave, and the use of the Weibull model resulted in slightly better fit than the log-linear model. The analyses for the goodness of fit and performance of the Weibull model produced root mean square errors of 0.059 to 0.824, percent root mean square errors of 3.105 to 21.182, determination coefficients of 0.747 to 0.989, slopes of 0.842 to 1.042, bias factor values of 0.505 to 1.309, and accuracy factor values of 1.263 to 6.874. Overall, this study suggests that the survival curves of pathogens on poultry products exposed to pulsed UV light are nonlinear and that the Weibull model may generally be a useful tool to describe the inactivation patterns for pathogenic microorganisms affiliated with poultry products.

  15. Targeted deletion of the ara operon of Salmonella typhimurium enhances L-arabinose accumulation and drives PBAD-promoted expression of anti-cancer toxins and imaging agents.

    Science.gov (United States)

    Hong, Hyun; Lim, Daejin; Kim, Geun-Joong; Park, Seung-Hwan; Sik Kim, Hyeon; Hong, Yeongjin; Choy, Hyon E; Min, Jung-Joon

    2014-01-01

    Tumor-specific expression of antitumor drugs can be achieved using attenuated Salmonella typhimurium harboring the PBAD promoter, which is induced by L-arabinose. However, L-arabinose does not accumulate because it is metabolized to D-xylulose-5-P by enzymes encoded by the ara operon in Salmonellae. To address this problem, we developed an engineered strain of S. typhimurium in which the ara operon is deleted. Linear DNA transformation was performed using λ red recombinase to exchange the ara operon with linear DNA carrying an antibiotic-resistance gene with homology to regions adjacent to the ara operon. The ara operon-deleted strain and its parental strain were transformed with a plasmid encoding Renilla luciferase variant 8 (RLuc8) or cytolysin A (clyA) under the control of the PBAD promoter. Luciferase assays demonstrated that RLuc8 expression was 49-fold higher in the ara operon-deleted S. typhimurium than in the parental strain after the addition of L-arabinose. In vivo bioluminescence imaging showed that the tumor tissue targeted by the ara operon-deleted Salmonella had a stronger imaging signal (~30-fold) than that targeted by the parental strain. Mice with murine colon cancer (CT26) that had been injected with the ara operon-deleted S. typhimurium expressing clyA showed significant tumor suppression. The present report demonstrates that deletion of the ara operon of S. typhimurium enhances L-arabinose accumulation and thereby drives PBAD-promoted expression of cytotoxic agents and imaging agents. This is a promising approach for tumor therapy and imaging.

  16. Circulating lipoproteins are a crucial component of host defense against invasive Salmonella typhimurium infection.

    Directory of Open Access Journals (Sweden)

    Mihai G Netea

    Full Text Available BACKGROUND: Circulating lipoproteins improve the outcome of severe Gram-negative infections through neutralizing lipopolysaccharides (LPS, thus inhibiting the release of proinflammatory cytokines. METHODS/PRINCIPAL FINDINGS: Low density lipoprotein receptor deficient (LDLR-/- mice, with a 7-fold increase in LDL, are resistant against infection with Salmonella typhimurium (survival 100% vs 5%, p<0.001, and 100 to 1000-fold lower bacterial burden in the organs, compared with LDLR+/+ mice. Protection was not due to differences in cytokine production, phagocytosis, and killing of Salmonella organisms. The differences were caused by the excess of lipoproteins, as hyperlipoproteinemic ApoE-/- mice were also highly resistant to Salmonella infection. Lipoproteins protect against infection by interfering with the binding of Salmonella to host cells, and preventing organ invasion. This leads to an altered biodistribution of the microorganisms during the first hours of infection: after intravenous injection of Salmonella into LDLR+/+ mice, the bacteria invaded the liver and spleen within 30 minutes of infection. In contrast, in LDLR-/- mice, Salmonella remained constrained to the circulation from where they were efficiently cleared, with decreased organ invasion. CONCLUSIONS: plasma lipoproteins are a potent host defense mechanism against invasive Salmonella infection, by blocking adhesion of Salmonella to the host cells and subsequent tissue invasion.

  17. Tetracycline consumption and occurrence of tetracycline resistance in Salmonella typhimurium phage types from Danish pigs

    DEFF Research Database (Denmark)

    Emborg, Hanne-Dorthe; Vigre, Håkan; Jensen, Vibeke Frøkjær;

    2007-01-01

    The aims of the present study were to investigate at the farm-owner level the effect of prescribed tetracycline consumption in pigs and different Salmonella Typhimurium phage types on the probability that the S. Typhimurium was resistant to tetracycline. In this study, 1,307 isolates were included......, originating from 877 farm owners, and data were analyzed using logistic regression. The analysis showed that both the S. Typhimurium phage type (p consumption (p = 0.0007) were significantly associated with tetracycline resistance. In particular, the phage type...... was strongly associated with tetracycline resistance. A further analysis of data from the Danish Integrated Antimicrobial Resistance Monitoring and Research Programme (DANMAP) indicates that the tetracycline-susceptible phage types only slowly become tetracycline resistant, although tetracycline consumption...

  18. Outbreak of Salmonella enterica serovar Typhimurium phage type DT41 in Danish poultry production

    DEFF Research Database (Denmark)

    Löfström, Charlotta; Hintzmann, Ann-Sofie; Sørensen, Gitte;

    2015-01-01

    Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) is one of the most prevalent serovars in Europe - where both poultry and poultry related products are common sources of human salmonellosis. Due to efficient control programs, the prevalence of S. Typhimurium in Danish...... slaughter house (n = 3, environmental sample and meat) were typed with multi locus variable number of tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE) to investigate the epidemiology of the outbreak. Based on PFGE results isolates were divided into four groups (Simpson's index...... of diversity (DI) = 0.24 ± 0.15). Due to the low DI, PFGE was not sufficient to provide information to unravel the outbreak. Based on MLVA typing the DT41 - (42/47 isolates) and the RDNC isolates (5/47) were split into nine groups (DI = 0.65 ± 0.14). When a maximum divergence at one locus was permitted...

  19. DNA topology and adaptation of Salmonella typhimurium to an intracellular environment.

    Science.gov (United States)

    Marshall, D G; Bowe, F; Hale, C; Dougan, G; Dorman, C J

    2000-01-01

    The expression of genes coding for determinants of DNA topology in the facultative intracellular pathogen Salmonella typhimurium was studied during adaptation by the bacteria to the intracellular environment of J774A.1 macrophage-like cells. A reporter plasmid was used to monitor changes in DNA supercoiling during intracellular growth. Induction of the dps and spv genes, previously shown to be induced in the macrophage, was detected, as was expression of genes coding for DNA gyrase, integration host factor and the nucleoid-associated protein H-NS. The topA gene, coding for the DNA relaxing enzyme topoisomerase I, was not induced. Reporter plasmid data showed that bacterial DNA became relaxed following uptake of S. typhimurium cells by the macrophage. These data indicate that DNA topology in S. typhimurium undergoes significant changes during adaptation to the intracellular environment. A model describing how this process may operate is discussed. PMID:10874730

  20. In vitro quantitative analysis of Salmonella typhimurium preference for amino acids secreted by human breast tumor

    Science.gov (United States)

    Choi, Eunpyo; Maeng, Bohee; Lee, Jae-hun; Chang, Hyung-kwan; Park, Jungyul

    2016-12-01

    Bacterial therapies have been paid significant attentions by their ability to penetrate deep into the solid tumor tissue and its propensity to naturally accumulate in tumors of living animals. Understanding the actual mechanism for bacteria to target the tumor is therapeutically crucial but is poorly understood. We hypothesized that amino acids released from the specific tumors induced bacteria to those tumors and the experiments for chemotactic response of bacteria toward the cancer secreting amino acids was then performed by using the diffusion based multiple chemical gradient generator constructed by in situ self-assembly of microspheres. The quantitative analysis was carried out by comparison of intensity using green fluorescent protein (GFP) tagged Salmonella typhimurium ( S. typhimurium) in the gradient generator, which showed the clear preference to the released amino acids, especially from breast cancer patients. The understanding chemotaxis toward the cancer secreting amino acids is essential for controlling S. typhimurium targeting in tumors and will allow for the development of bacterial therapies.

  1. Experimental Salmonella typhimurium infections in rats. III. Transfer of immunity with primed lymphocyte subpopulations

    DEFF Research Database (Denmark)

    Hougen, H P; Jensen, E T

    1990-01-01

    The protective effect of primed lymphocytes against a lethal dose of Salmonella typhimurium was studied in athymic and euthymic LEW rats. Primed lymphocytes were obtained by inoculating euthymic and thymus-grafted animals with a non-lethal dose of Salmonella typhimurium. Four weeks after...... the infection, spleen lymphocytes were separated by panning technique and antibody-coated magnetic microsphere separation using antibodies to pan T and pan B lymphocytes and subsequent sorting in a fluorescence activated cell sorter by means of monoclonal antibodies against CD4+ and CD8+ cells. Euthymic...... and athymic rats were injected with different doses of primed pan B, pan T, CD4+ and CD8+ T lymphocytes before inoculation with a lethal bacterial dose. Most of the animals treated with pan B, pan T or CD8+ cells died within two weeks. After treatment with primed CD4+ cells, only six of 39 animals died. Doses...

  2. Molecular detection assay of five Salmonella serotypes of public interest: Typhimurium, Enteritidis, Newport, Heidelberg, and Hadar.

    Science.gov (United States)

    Bugarel, M; Tudor, A; Loneragan, G H; Nightingale, K K

    2017-03-01

    Foodborne illnesses due to Salmonella represent an important public-health concern worldwide. In the United States, a majority of Salmonella infections are associated with a small number of serotypes. Furthermore, some serotypes that are overrepresented among human disease are also associated with multi-drug resistance phenotypes. Rapid detection of serotypes of public-health concern might help reduce the burden of salmonellosis cases and limit exposure to multi-drug resistant Salmonella. We developed a two-step real-time PCR-based rapid method for the identification and detection of five Salmonella serotypes that are either overrepresented in human disease or frequently associated with multi-drug resistance, including serotypes Enteritidis, Typhimurium, Newport, Hadar, and Heidelberg. Two sets of four markers were developed to detect and differentiate the five serotypes. The first set of markers was developed as a screening step to detect the five serotypes; whereas, the second set was used to further distinguish serotypes Heidelberg, Newport and Hadar. The utilization of these markers on a two-step investigation strategy provides a diagnostic specificity of 97% for the detection of Typhimurium, Enteritidis, Heidelberg, Infantis, Newport and Hadar. The diagnostic sensitivity of the detection makers is >96%. The availability of this two-step rapid method will facilitate specific detection of Salmonella serotypes that contribute to a significant proportion of human disease and carry antimicrobial resistance.

  3. The Salmonella pathogenicity island 2-encoded type III secretion system is essential for the survival of Salmonella enterica serovar Typhimurium in free-living amoebae.

    Science.gov (United States)

    Bleasdale, Benjamin; Lott, Penelope J; Jagannathan, Aparna; Stevens, Mark P; Birtles, Richard J; Wigley, Paul

    2009-03-01

    Free-living amoebae represent a potential reservoir and predator of Salmonella enterica. Through the use of type III secretion system (T3SS) mutants and analysis of transcription of selected T3SS genes, we demonstrated that the Salmonella pathogenicity island 2 is highly induced during S. enterica serovar Typhimurium infection of Acanthamoeba polyphaga and is essential for survival within amoebae.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2012-01-01

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

  6. Use of acetic and citric acids to control Salmonella Typhimurium in tahini (sesame paste).

    Science.gov (United States)

    Al-Nabulsi, Anas A; Olaimat, Amin N; Osaili, Tareq M; Shaker, Reyad R; Zein Elabedeen, Noor; Jaradat, Ziad W; Abushelaibi, Aisha; Holley, Richard A

    2014-09-01

    Since tahini and its products have been linked to Salmonella illness outbreaks and product recalls in recent years, this study assessed the ability of Salmonella Typhimurium to survive or grow in commercial tahini and when hydrated (10% w/v in water), treated with 0.1%-0.5% acetic or citric acids, and stored at 37, 21 and 10 °C for 28 d. S. Typhimurium survived in commercial tahini up to 28 d but was reduced in numbers from 1.7 to 3.3 log10 CFU/ml. However, in the moist or hydrated tahini, significant growth of S. Typhimurium occurred at the tested temperatures. Acetic and citric acids at ≤0.5% reduced S. Typhimurium by 2.7-4.8 log10 CFU/ml and 2.5-3.8 log10 CFU/ml, respectively, in commercial tahini at 28 d. In hydrated tahini the organic acids were more effective. S. Typhimurium cells were not detected in the presence of 0.5% acetic acid after 7 d or with 0.5% citric acid after 21 d at the tested temperatures. The ability of S. Typhimurium to grow or survive in commercial tahini and products containing hydrated tahini may contribute to salmonellosis outbreaks; however, use of acetic and citric acids in ready-to-eat foods prepared from tahini can significantly minimize the risk associated with this pathogen.

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

    Science.gov (United States)

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

    2014-01-03

    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.

  8. Comparative genome analysis of the high pathogenicity Salmonella Typhimurium strain UK-1.

    Directory of Open Access Journals (Sweden)

    Yingqin Luo

    Full Text Available Salmonella enterica serovar Typhimurium, a gram-negative facultative rod-shaped bacterium causing salmonellosis and foodborne disease, is one of the most common isolated Salmonella serovars in both developed and developing nations. Several S. Typhimurium genomes have been completed and many more genome-sequencing projects are underway. Comparative genome analysis of the multiple strains leads to a better understanding of the evolution of S. Typhimurium and its pathogenesis. S. Typhimurium strain UK-1 (belongs to phage type 1 is highly virulent when orally administered to mice and chickens and efficiently colonizes lymphoid tissues of these species. These characteristics make this strain a good choice for use in vaccine development. In fact, UK-1 has been used as the parent strain for a number of nonrecombinant and recombinant vaccine strains, including several commercial vaccines for poultry. In this study, we conducted a thorough comparative genome analysis of the UK-1 strain with other S. Typhimurium strains and examined the phenotypic impact of several genomic differences. Whole genomic comparison highlights an extremely close relationship between the UK-1 strain and other S. Typhimurium strains; however, many interesting genetic and genomic variations specific to UK-1 were explored. In particular, the deletion of a UK-1-specific gene that is highly similar to the gene encoding the T3SS effector protein NleC exhibited a significant decrease in oral virulence in BALB/c mice. The complete genetic complements in UK-1, especially those elements that contribute to virulence or aid in determining the diversity within bacterial species, provide key information in evaluating the functional characterization of important genetic determinants and for development of vaccines.

  9. Thioridazine protects the mouse from a virulent infection by Salmonella enterica serovar Typhimurium 74

    DEFF Research Database (Denmark)

    Dasgupta, Asish; Mukherjee, Sayanti; Chaki, Shaswati

    2010-01-01

    When administered to mice at doses of 100microg/mouse and 200microg/mouse, thioridazine (TDZ) significantly protected animals from the lethality produced by a virulent strain of Salmonella enterica serovar Typhimurium and reduced the number of bacteria retrieved from the spleen, liver and heart b...... to rapid induction of the two-step PmrA/B regulon that results in the eventual synthesis and insertion of lipid A into the nascent lipopolysaccharide layer of the outer membrane....

  10. Evidence for regulation of gluconeogenesis by the fructose phosphotransferase system in Salmonella typhimurium.

    OpenAIRE

    Chin, A M; Feucht, B U; Saier, M.H.

    1987-01-01

    A genetic locus designated fruR, previously mapped to min 3 on the Salmonella typhimurium chromosome, gave rise to constitutive expression of the fructose (fru) regulon and pleiotropically prevented growth on all Krebs cycle intermediates. Regulatory effects of fruR were independent of cyclic AMP and its receptor protein and did not prevent uptake of Krebs cycle intermediates. Instead, the phosphotransferase system appeared to regulate gluconeogenesis by controlling the activities of phosphoe...

  11. An Outbreak of Salmonella Typhimurium infections in Denmark, Norway and Sweden, 2008

    DEFF Research Database (Denmark)

    Bruun, T; Sørensen, Gitte; Forshell, L P

    2009-01-01

    In November-December 2008, Norway and Denmark independently identified outbreaks of Salmonella Typhimurium infections characterised in the multiple-locus variable number of tandem repeats analysis (MLVA) by a distinct profile. Outbreak investigations were initiated independently in the two countr......-border outbreaks. Differences in legal requirements for food safety in neighbouring countries may be a challenge in terms of communication with consumers in areas where cross-border shopping is common....

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

    Science.gov (United States)

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

    2013-07-01

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

  13. Iron-regulated excretion of alpha-keto acids by Salmonella typhimurium.

    OpenAIRE

    Reissbrodt, R.; Kingsley, R; Rabsch, W.; Beer, W.; Roberts, M.; Williams, P H

    1997-01-01

    Excretion of alpha-keto acids by clinical isolates and laboratory strains of Salmonella typhimurium was determined by high-performance liquid chromatography analysis of culture supernatants. The levels of excretion increased markedly with increasing iron stress imposed by the presence of alpha,alpha'-dipyridyl or conalbumin in the medium. The major product was pyruvic acid, but significant concentrations of alpha-ketoglutaric acid, alpha-ketoisovaleric acid, and alpha-ketoisocaproic acid were...

  14. Elimination of Salmonella enterica serovar Typhimurium in artificially contaminated eggs through correct cooking and frying procedures

    Directory of Open Access Journals (Sweden)

    Geovana Dagostim Savi

    2011-06-01

    Full Text Available Salmonellosis is a serious foodborne disease associated with the presence of bacteria in eggs or foods containing raw eggs. However, the use of appropriate procedures of cooking and frying can eliminate this contamination. There are few studies on the elimination of contamination of Salmonella in hens' eggs through typical frying procedures, especially for Salmonella enterica serovar Typhimurium (or S. typhimurium. The aim of this study was to determine the appropriate conditions for cooking and frying hens' eggs artificially contaminated with S. typhimurium, making them free of bacterial contamination. Hens' eggs were artificially contaminated with S. typhimurium and subjected to various processes of cooking, frying and food preparation. It was observed that the minimum time necessary to eliminate contamination through cooking procedures is 5 minutes after the water starts boiling, and also that, cooking in the microwave oven complete eliminates the bacterial contamination. When the eggs were fried on both sides, keeping the yolk hard, a complete bacterial elimination was observed. Mayonnaise prepared with vinegar presented a decrease in bacterial colonies when compared mayonese prepared with lemon.

  15. EVALUATION OF AN O-ANTIGEN ELISA FOR SCREENING CATTLE HERDS FOR SALMONELLA-TYPHIMURIUM

    DEFF Research Database (Denmark)

    Hoorfar, Jeffrey; Bitsch, V.

    1995-01-01

    A total of 2585 serum samples from 62 dairy herds located in four different regions of Denmark were tested in an O-antigen (0:1,4,5,12)-based ELISA for the detection of antibodies against Salmonella typhimurium. Ten closed herds from an island with no reported occurrence of salmonellosis for seve......A total of 2585 serum samples from 62 dairy herds located in four different regions of Denmark were tested in an O-antigen (0:1,4,5,12)-based ELISA for the detection of antibodies against Salmonella typhimurium. Ten closed herds from an island with no reported occurrence of salmonellosis...... the salmonellosis-free island were ELISA-negative, and all but one of the 12 S typhimurium-infected herds were ELISA-positive, which resulted in a herd test sensitivity of 0.92 and herd test specificity of 1.0. Eleven of the 12 S typhimurium-infected herds were negative in a blocking ELISA based on a monoclonal...

  16. The effect of nitric oxide combined with fluoroquinolones against Salmonella enterica serovar Typhimurium in vitro

    Directory of Open Access Journals (Sweden)

    Coban AY

    2003-01-01

    Full Text Available Two regulons, soxRS and marRAB, are associated with resistance to quinolones or multiple antibiotic in Salmonella enterica serovar Typhimurium. These regulons are activated by nitric oxide and redox-cycling drugs, such as paraquat and cause on activation of the acrAB-encoded efflux pump. In this study, we investigated the effect of nitric oxide (NO alone and in combination with ofloxacin, ciprofloxacin, and pefloxacin against S. typhimurium clinical isolates and mutant strains in vitro. We did not observe synergistic effect against clinical isolates and SH5014 (parent strain of acr mutant, while we found synergistic effect against PP120 (soxRS mutant and SH7616 (an acr mutant S. typhimurium for all quinolones. Our results suggest that the efficiencies of some antibiotics, including ofloxacin, ciprofloxacin, and pefloxacin are decreased via activation of soxRS and marRAB regulons by NO in S. enterica serovar Typhimurium. Further studies are warranted to establish the interaction of NO with the genes of Salmonella and, with multiple antibiotic resistance.

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

    Science.gov (United States)

    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...

  18. Live-cell imaging of Salmonella Typhimurium interaction with zebrafish larvae after injection and immersion delivery methods.

    Science.gov (United States)

    Varas, Macarena; Fariña, Alonso; Díaz-Pascual, Francisco; Ortíz-Severín, Javiera; Marcoleta, Andrés E; Allende, Miguel L; Santiviago, Carlos A; Chávez, Francisco P

    2017-04-01

    The zebrafish model has been used to determine the role of vertebrate innate immunity during bacterial infections. Here, we compare the in vivo immune response induced by GFP-tagged Salmonella Typhimurium inoculated by immersion and microinjection in transgenic zebrafish larvae. Our novel infection protocols in zebrafish allow live-cell imaging of Salmonella colonization.

  19. Curcumin increases the pathogenicity of Salmonella enterica serovar Typhimurium in murine model.

    Directory of Open Access Journals (Sweden)

    Sandhya A Marathe

    Full Text Available Curcumin has gained immense importance for its vast therapeutic and prophylactic applications. Contrary to this, our study reveals that it regulates the defense pathways of Salmonella enterica serovar Typhimurium (S. Typhimurium to enhance its pathogenicity. In a murine model of typhoid fever, we observed higher bacterial load in Peyer's patches, mesenteric lymph node, spleen and liver, when infected with curcumin-treated Salmonella. Curcumin increased the resistance of S. Typhimurium against antimicrobial agents like antimicrobial peptides, reactive oxygen and nitrogen species. This increased tolerance might be attributed to the up-regulation of genes involved in resistance against antimicrobial peptides--pmrD and pmrHFIJKLM and genes with antioxidant function--mntH, sodA and sitA. We implicate that iron chelation property of curcumin have a role in regulating mntH and sitA. Interestingly, we see that the curcumin-mediated modulation of pmr genes is through the PhoPQ regulatory system. Curcumin downregulates SPI1 genes, required for entry into epithelial cells and upregulates SPI2 genes required to intracellular survival. Since it is known that the SPI1 and SPI2 system can be regulated by the PhoPQ system, this common regulator could explain curcumin's mode of action. This data urges us to rethink the indiscriminate use of curcumin especially during Salmonella outbreaks.

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

    Science.gov (United States)

    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.

  1. Salmonella Genomic Island 1 (SGI1) and genetic characteristics of animal and food isolates of Salmonella typhimurium DT104 in Hungary.

    Science.gov (United States)

    Fekete, Péter Zsolt; Nagy, Béla

    2008-03-01

    To study the genetic characteristics of DT104 strains of Salmonella Typhimurium and the prevalence of Salmonella Genomic Island (SGI1) in Hungary, 140 recent Salmonella strains of food and animal origin were examined. For the first time in Hungary, the SGI1 was found in 17 out of 59 S. Typhimurium isolates (all proven to be DT104 phage type). These 17 strains were then subtyped by pulsed-field gel electrophoresis (PFGE) into 6 pulsotypes which were less correlated with the geographic origin than with the animal species of origin.

  2. TNT biotransformation potential of the clinical isolate of Salmonella typhimurium - potential ecological implications

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    Litake Geetanjali

    2005-01-01

    Full Text Available Out of fifty-six isolates screened three bacterial strains enriched with TNT either as sole source of nitrogen (for Salmonella typhimurium, Klebsiella pneumoniae or along with co-substrate (for Acinetobacter baumannii, have been carried out nitro group reduction under aerobic conditions. During studies, S. typhimurium found to have high potential (100% of 50 mg l-l in removal of TNT, than K. pneumoniae (70% of 20 mg l-l and A. baumannii (52% of 40 mg l-l, in presence of co-substrate. Therefore studies were focused on S. typhimurium, which had shown good growth, and protein contents, with disappearance of TNT, and concomitantly release of nitrite over the period of time. Removal of TNT was analyzed by HPLC, and nitrite liberation was consistently found coincided with TNT disappearance from the medium. As compared to earlier reports, 100% disappearance of TNT within 30 h by S. typhimurium is encouraging, and may indicate its potential in bioremediation of TNT. This is the first report on S. typhimurium, Klebsiella pneumoniae and Acinetobacter baumannii for transformation of TNT with nitrite release into the medium.

  3. Contribution of the SirA regulon to biofilm formation in Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Teplitski, Max; Al-Agely, Ali; Ahmer, Brian M M

    2006-11-01

    Orthologues of the Salmonella enterica serovar Typhimurium (S. typhimurium) BarA/SirA two-component system are important for biofilm formation and virulence in many gamma-Proteobacteria. In S. typhimurium, SirA activates the csrB and csrC carbon storage regulatory RNAs and the virulence gene regulators hilA and hilC. The regulatory RNAs antagonize the activity of the CsrA protein, allowing translation of those same virulence genes, and inhibiting the translation of flagellar genes. In this report, it was determined that SirA and the Csr system also control the fim operon that encodes type 1 fimbriae. sirA orthologues in other bacterial species, and the fim operon of S. typhimurium, are known to play a role in biofilm formation; therefore, all members of the S. typhimurium sirA regulon were tested for in vitro biofilm production. A sirA mutant, a csrB csrC double mutant, and a fimI mutant, were all defective in biofilm formation. Conversely, inactivation of flhDC increased biofilm formation. Therefore, SirA activates csrB, csrC and the fim operon to promote biofilm formation. In turn, csrB and csrC promote the translation of the fim operon, while at the same time inhibiting the translation of flagella, which are inhibitory to biofilm formation.

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

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    Kumar Ajay

    2012-07-01

    Full Text Available Abstract Background Dietary rice bran consists of many bioactive components with disease fighting properties; including the capacity to modulate the gut microbiota. Studies point to the important roles of the gut microbiota and the mucosal epithelium in the establishment of protection against enteric pathogens, such as Salmonella. The ability of rice bran to reduce the susceptibility of mice to a Salmonella infection has not been previously investigated. Therefore, we hypothesized that the incorporation of rice bran into the diet would inhibit the colonization of Salmonella in mice through the induction of protective mucosal responses. Results Mice were fed diets containing 0%, 10% and 20% rice bran for one week prior to being orally infected with Salmonella enterica serovar Typhimurium. We found that mice consuming the 10 and 20% rice bran diets exhibited a reduction in Salmonella fecal shedding for up to nine days post-infection as compared to control diet fed animals (p Lactobacillus spp. in rice bran fed mice (p Salmonella entry into mouse small intestinal epithelial cells. Conclusions Increasing rice bran consumption represents a novel dietary means for reducing susceptibility to enteric infection with Salmonella and potentially via induction of native Lactobacillus spp.

  5. Detection and characterization of Salmonella typhimurium from a dairy herd in North Dakota.

    Science.gov (United States)

    Nolan, L K; Giddings, C W; Boland, E W; Steffen, D J; Brown, J; Misek, A

    1995-01-01

    Nasal secretions, faecal samples and buffy coats were obtained from 102 cattle from a North Dakota dairy herd with a history of calf scours. Treated buffy coats, faecal samples and nasal secretions were inoculated into tetrathionate broth (TB), incubated at 37 degrees C overnight, and plated onto brilliant green agar medium with novobiocin (BGAN). The TB was left at room temperature for 5 days and then used to inoculate fresh TB. The fresh TB was incubated at 37 degrees C over night and plated onto BGAN medium. All the plates were incubated at 37 degrees C over night and observed for Salmonella-like growth. Suspect colonies were further tested and Salmonella isolates were serotyped by the National Veterinary Services laboratory. Twenty-two of the 36 calves sampled harboured S. typhimurium in their faeces, but no samples from cows were positive. No Salmonella were isolated from the buffy coats, but 4 calves were shown to have Salmonella in their nasal secretions. Extended enrichment of the faecal cultures in TB resulted in a significant increase in Salmonella isolations, although 2 samples were positive following the initial enrichment period and not after secondary enrichment. The typical Salmonella isolate detected from this herd contained a transmissible R-plasmid encoding resistance to tetracycline, kanamycin, sulphisoxazole and ampicillin. This study confirmed that delayed secondary enrichment in TB is superior to primary enrichment for detection of Salmonella from cattle.

  6. DNA microarray analysis of Salmonella serotype Typhimurium strains causing different symptoms of disease

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    Helms Morten

    2010-03-01

    Full Text Available Abstract Background Salmonella enterica subsp. enterica is one of the leading food-borne pathogens in the USA and European countries. Outcome of human Salmonella serotype Typhimurium infections ranges from mild self-limiting diarrhoea to severe diarrhoea that requires hospitalization. Increased knowledge of the mechanisms that are responsible for causing infection and especially the severity of infection is of high interest. Results Strains were selected from patients with mild infections (n = 9 and patients with severe infections (n = 9 and clinical data allowed us to correct for known underlying diseases. Additionally, outbreak isolates (n = 3 were selected. Strains were analyzed on a DNA-DNA microarray for presence or absence of 281 genes covering marker groups of genes related to pathogenicity, phages, antimicrobial resistance, fimbriae, mobility, serotype and metabolism. Strains showed highly similar profiles when comparing virulence associated genes, but differences between strains were detected in the prophage marker group. The Salmonella virulence plasmid was present in 72% of the strains, but presence or absence of the virulence plasmid did not correspond to disease symptoms. A dendrogram clustered strains into four groups. Clustering confirmed DT104 as being a clonal phagetype. Clustering of the remaining strains was mainly correlated to presence or absence of the virulence plasmid and mobile elements such as transposons. Each of the four clusters in the tree represented an almost equal amount of strains causing severe or mild symptoms of infection. Conclusions We investigated clinical significance of known virulence factors of Salmonella serotype Typhimurium strains causing different disease symptoms, and conclude that the few detected differences in Salmonella serotype Typhimurium do not affect outcome of human disease.

  7. Some putative prebiotics increase the severity of Salmonella enterica serovar Typhimurium infection in mice

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    Lahtinen Sampo

    2009-01-01

    Full Text Available Abstract Background Prebiotics are non-digestible food ingredients believed to beneficially affect host health by selectively stimulating the growth of the beneficial bacteria residing in the gut. Such beneficial bacteria have been reported to protect against pathogenic infections. However, contradicting results on prevention of Salmonella infections with prebiotics have been published. The aim of the present study was to examine whether S. Typhimurium SL1344 infection in mice could be prevented by administration of dietary carbohydrates with different structures and digestibility profiles. BALB/c mice were fed a diet containing 10% of either of the following carbohydrates: inulin, fructo-oligosaccharide, xylo-oligosaccharide, galacto-oligosaccharide, apple pectin, polydextrose or beta-glucan for three weeks prior to oral Salmonella challenge (107 CFU and compared to mice fed a cornstarch-based control diet. Results The mice fed with diets containing fructo-oligosaccharide (FOS or xylo-oligosaccharide (XOS had significantly higher (P < 0.01 and P < 0.05 numbers of S. Typhimurium SL1344 in liver, spleen and mesenteric lymph nodes when compared to the mice fed with the cornstarch-based control diet. Significantly increased amounts (P < 0.01 of Salmonella were detected in ileal and fecal contents of mice fed with diets supplemented with apple pectin, however these mice did not show significantly higher numbers of S. Typhimyrium in liver, spleen and lymph nodes than animals from the control group (P < 0.20. The acute-phase protein haptoglobin was a good marker for translocation of S. Typhimurium in mice. In accordance with the increased counts of Salmonella in the organs, serum concentrations of haptoglobin were significantly increased in the mice fed with FOS or XOS (P < 0.001. Caecum weight was increased in the mice fed with FOS (P < 0.01, XOS (P < 0.01, or polydextrose (P < 0.001, and caecal pH was reduced in the mice fed with polydextrose (P < 0

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

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    Porwollik Steffen

    2011-03-01

    Full Text Available Abstract 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

  9. Immuno-capture and in situ detection of Salmonella typhimurium on a novel microfluidic chip

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Renjie, E-mail: 1058464972@qq.com [College of Chemistry and Chemical Engineering, Chongqing University, No. 174, St. Shazheng, Shapingba District, Chongqing (China); Ni, Yanan, E-mail: 468885029@qq.com [College of Chemistry and Chemical Engineering, Chongqing University, No. 174, St. Shazheng, Shapingba District, Chongqing (China); Xu, Yi, E-mail: xuyibbd@sina.com [College of Chemistry and Chemical Engineering, Chongqing University, No. 174, St. Shazheng, Shapingba District, Chongqing (China); National Center for International Research of Micro/Nano-System and New Material Technology, No. 174, St. Shazhengjie, Shapingba District, Chongqing (China); Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology for National Defense, Chongqing (China); Jiang, Yan, E-mail: 919865356@qq.com [College of Chemistry and Chemical Engineering, Chongqing University, No. 174, St. Shazheng, Shapingba District, Chongqing (China); Dong, Chunyan, E-mail: 774176325@qq.com [College of Chemistry and Chemical Engineering, Chongqing University, No. 174, St. Shazheng, Shapingba District, Chongqing (China); Chuan, Na, E-mail: 814859441@qq.com [College of Chemistry and Chemical Engineering, Chongqing University, No. 174, St. Shazheng, Shapingba District, Chongqing (China)

    2015-01-01

    Highlights: • A novel microfluidic chip and a LIF microsystem were designed and fabricated. • Salmonella typhimurium was captured and labeled by specific immuno-capture on chip. • CdSe/ZnS quantum dots-labeled bacteria were detected by in situ analysis using LIF microsystem. • The proposed method has potential application in practice. - Abstract: The new method presented in this article achieved the goal of capturing Salmonella typhimurium via immunoreaction and rapid in situ detection of the CdSe/ZnS quantum dots (QDs) labeled S. typhimurium by self-assembly light-emitting diode-induced fluorescence detection (LIF) microsystem on a specially designed multichannel microfluidic chip. CdSe/ZnS QDs were used as fluorescent markers improving detection sensitivity. The microfluidic chip developed in this study was composed of 12 sample channels, 3 mixing zones, and 6 immune reaction zones, which also acted as fluorescence detection zones. QDs–IgG–primary antibody complexes were generated by mixing CdSe/ZnS QDs conjugated secondary antibody (QDs–IgG) and S. typhimurium antibody (primary antibody) in mixing zones. Then, the complexes went into immune reaction zones to label previously captured S. typhimurium in the sandwich mode. The capture rate of S. typhimurium in each detection zone was up to 70%. The enriched QDs-labeled S. typhimurium was detected using a self-assembly LIF microsystem. A good linear relationship was obtained in the range from 3.7 × 10 to 3.7 × 10{sup 5} cfu mL{sup −1} using the equation I = 0.1739 log (C) − 0.1889 with R{sup 2} = 0.9907, and the detection limit was down to 37 cfu mL{sup −1}. The proposed method of online immunolabeling with QDs for in situ fluorescence detection on the designed multichannel microfluidic chip had been successfully used to detect S. typhimurium in pork sample, and it has shown potential advantages in practice.

  10. Detection of Salmonella Typhimurium on Spinach Using Phage-Based Magnetoelastic Biosensors

    Science.gov (United States)

    Wang, Fengen; Horikawa, Shin; Hu, Jiajia; Wikle, Howard C.; Chen, I-Hsuan; Du, Songtao; Liu, Yuzhe; Chin, Bryan A.

    2017-01-01

    Phage-based magnetoelastic (ME) biosensors have been studied as an in-situ, real-time, wireless, direct detection method of foodborne pathogens in recent years. This paper investigates an ME biosensor method for the detection of Salmonella Typhimurium on fresh spinach leaves. A procedure to obtain a concentrated suspension of Salmonella from contaminated spinach leaves is described that is based on methods outlined in the U.S. FDA Bacteriological Analytical Manual for the detection of Salmonella on leafy green vegetables. The effects of an alternative pre-enrichment broth (LB broth vs. lactose broth), incubation time on the detection performance and negative control were investigated. In addition, different blocking agents (BSA, Casein, and Superblock) were evaluated to minimize the effect of nonspecific binding. None of the blocking agents was found to be superior to the others, or even better than none. Unblocked ME biosensors were placed directly in a concentrated suspension and allowed to bind with Salmonella cells for 30 min before measuring the resonant frequency using a surface-scanning coil detector. It was found that 7 h incubation at 37 °C in LB broth was necessary to detect an initial spike of 100 cfu/25 g S. Typhimurium on spinach leaves with a confidence level of difference greater than 95% (p foodborne pathogens on fresh products. PMID:28212322

  11. Detection of Salmonella Typhimurium on Spinach Using Phage-Based Magnetoelastic Biosensors

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    Fengen Wang

    2017-02-01

    Full Text Available Phage-based magnetoelastic (ME biosensors have been studied as an in-situ, real-time, wireless, direct detection method of foodborne pathogens in recent years. This paper investigates an ME biosensor method for the detection of Salmonella Typhimurium on fresh spinach leaves. A procedure to obtain a concentrated suspension of Salmonella from contaminated spinach leaves is described that is based on methods outlined in the U.S. FDA Bacteriological Analytical Manual for the detection of Salmonella on leafy green vegetables. The effects of an alternative pre-enrichment broth (LB broth vs. lactose broth, incubation time on the detection performance and negative control were investigated. In addition, different blocking agents (BSA, Casein, and Superblock were evaluated to minimize the effect of nonspecific binding. None of the blocking agents was found to be superior to the others, or even better than none. Unblocked ME biosensors were placed directly in a concentrated suspension and allowed to bind with Salmonella cells for 30 min before measuring the resonant frequency using a surface-scanning coil detector. It was found that 7 h incubation at 37 °C in LB broth was necessary to detect an initial spike of 100 cfu/25 g S. Typhimurium on spinach leaves with a confidence level of difference greater than 95% (p < 0.05. Thus, the ME biosensor method, on both partly and fully detection, was demonstrated to be a robust and competitive method for foodborne pathogens on fresh products.

  12. Inhibition and inactivation of Salmonella typhimurium biofilms from polystyrene and stainless steel surfaces by essential oils and phenolic constituent carvacrol.

    Science.gov (United States)

    Soni, Kamlesh A; Oladunjoye, Ademola; Nannapaneni, Ramakrishna; Schilling, M Wes; Silva, Juan L; Mikel, Benjy; Bailey, R Hartford

    2013-02-01

    Persistence of Salmonella biofilms within food processing environments is an important source of Salmonella contamination in the food chain. In this study, essential oils of thyme and oregano and their antimicrobial phenolic constituent carvacrol were evaluated for their ability to inhibit biofilm formation and inactivate preformed Salmonella biofilms. A crystal violet staining assay and CFU measurements were utilized to quantify biofilm cell mass, with evaluating factors such as strain variation, essential oil type, their concentrations, exposure time, as well as biofilm formation surface. Of the three Salmonella strains, Salmonella Typhimurium ATCC 23564 and Salmonella Typhimurium ATCC 19585 produced stronger biofilms than Salmonella Typhimurium ATCC 14028. Biofilm formation by different Salmonella strains was 1.5- to 2-fold higher at 22°C than at 30 or 37°C. The presence of nonbiocidal concentrations of thyme oil, oregano oil, and phenolic carvacrol at 0.006 to 0.012% suppressed Salmonella spp. biofilm formation 2- to 4-fold, but could not completely eliminate biofilm formation. There was high correlation in terms of biofilm inactivation, as determined by the crystal violet-stained optical density (at a 562-nm wavelength) readings and the viable CFU counts. Reduction of biofilm cell mass was dependent on antimicrobial concentration. A minimum concentration of 0.05 to 0.1% of these antimicrobial agents was needed to reduce a 7-log CFU biofilm mass to a nondetectable level on both polystyrene and stainless steel surfaces within 1 h of exposure time.

  13. Salmonella typhimurium A1-R tumor targeting in immunocompetent mice is enhanced by a traditional Chinese medicine herbal mixture.

    Science.gov (United States)

    Zhang, Yong; Zhang, Nan; Su, Shibing; Hoffman, Robert M; Zhao, Ming

    2013-05-01

    We have developed a bacterial cancer therapy strategy using the genetically-engineered strain Salmonella typhimurium A1-R (A1-R). A1-R is auxotrophic for leu and arg which attenuates bacterial growth in normal tissue but allows high tumor virulence. A1-R is effective against metastatic human and murine cancer cell lines in clinically-relevant nude-mouse models. However, A1-R treatment of tumors in immunocompetent mouse models with high doses is limited by toxicity. The current study evaluated a traditional Chinese medicine (TCM) herbal mixture in combination with A1-R therapy in a syngeneic metastatic immunocompetent mouse model of highly aggressive lung cancer. In a model of Lewis lung carcinoma, the combination of a TCM herbal mixture and S. typhimurium A1-R enabled bacteria to be safely administered at the large dose of 2 × 10(7) colony forming units once a week i.v. with increased treatment efficacy and reduced toxicity compared to monotherapy with A1-R. The herbal mixture prevented body weight loss, spleen weight gain and liver infection by A1-R, as well as hemorrhagic lesions on the skin, liver, and spleen, all observed with A1-R monotherapy. The results of the present study suggest that the combination of A1-R and TCM has important potential for therapy of highly aggressive types of cancer, including those which are resistant to standard therapy.

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

    Science.gov (United States)

    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

  15. A Genome-Scale Modeling Approach to Quantify Biofilm Component Growth of Salmonella Typhimurium.

    Science.gov (United States)

    Ribaudo, Nicholas; Li, Xianhua; Davis, Brett; Wood, Thomas K; Huang, Zuyi Jacky

    2017-01-01

    Salmonella typhimurium (S. typhimurium) is an extremely dangerous foodborne bacterium that infects both animal and human subjects, causing fatal diseases around the world. Salmonella's robust virulence, antibiotic-resistant nature, and capacity to survive under harsh conditions are largely due to its ability to form resilient biofilms. Multiple genome-scale metabolic models have been developed to study the complex and diverse nature of this organism's metabolism; however, none of these models fully integrated the reactions and mechanisms required to study the influence of biofilm formation. This work developed a systems-level approach to study the adjustment of intracellular metabolism of S. typhimurium during biofilm formation. The most advanced metabolic reconstruction currently available, STM_v1.0, was 1st extended to include the formation of the extracellular biofilm matrix. Flux balance analysis was then employed to study the influence of biofilm formation on cellular growth rate and the production rates of biofilm components. With biofilm formation present, biomass growth was examined under nutrient rich and nutrient deficient conditions, resulting in overall growth rates of 0.8675 and 0.6238 h(-1) respectively. Investigation of intracellular flux variation during biofilm formation resulted in the elucidation of 32 crucial reactions, and associated genes, whose fluxes most significantly adapt during the physiological response. Experimental data were found in the literature to validate the importance of these genes for the biofilm formation of S. typhimurium. This preliminary investigation on the adjustment of intracellular metabolism of S. typhimurium during biofilm formation will serve as a platform to generate hypotheses for further experimental study on the biofilm formation of this virulent bacterium.

  16. Rectal stenosis in pigs associated with Salmonella Typhimurium and porcine circovirus type 2 (PCV2 infection

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    Tatiane Terumi Negrão Watanabe

    2011-06-01

    Full Text Available Rectal stricture is an acquired annular fibrous constriction of the rectum that results from a variety of chronic necrotizing enteric diseases. In pigs, it is in most cases a sequel of Salmonella infection. Porcine circovirus type 2 (PCV2 is a known pathogen causing immunosuppression in pigs worldwide. PCV2 infected pigs may be predisposed to salmonellosis. In this report, rectal stenosis was observed in 160 pigs from a herd that experienced an outbreak of enteric salmonellosis over a 4-month period. Distension of the abdominal wall and diarrhea were the main clinical signs observed. Five animals were analyzed showing annular cicatrization of the rectal wall 5.0-7.0 cm anterior to the anorectal junction and Salmonella-positive immunostaining in the large intestine. Salmonella Typhimurium was isolated from fragments of the large intestine. Porcine circovirus type 2 antigen was observed in the mesenteric lymph-node in 4 pigs and in the large intestine in 3 pigs.

  17. Isolation and Molecular Identification of Salmonella typhimurium from Chicken Meat in Iraq

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    Aseel A. Saeed

    2013-06-01

    Full Text Available This study was conducted to determine the prevalence of Salmonellae contamination of chicken meat imported from different origin to local markets in south of Iraq (Diwaniya. The bacteria were cultured, isolated and biochemically characterized by the analytical profiling index (API 20E system. The 16s rRNA and invA gene primers were selected specifically for the detection of Salmonella to amplify a 406 and 558 bp DNA fragments, respectively. The results of this study showed that 22 Salmonella isolates were detected by polymerase chain reaction (PCR from 100 chicken meats and only 7 isolates out of 22 were identified as S. typhimurium, the highest percent of isolates were 83.8 % for India origin and the lowest percent were 25% from Jordan origin.

  18. Factors influencing phagocytosis of Salmonella typhimurium by macrophages in murine schistosomiasis

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    Muniz-Junqueira Maria Imaculada

    1997-01-01

    Full Text Available We investigated the influence of Salmonella typhimurium load and specific antibodies on phagocytosis in schistosomiasis. Macrophages from Schistosoma mansoni-infected mice showed depressed capacity to increase the phagocytosis in the presence of a high bacterial load, due to a reduced involvement of these cells in phagocytosis and to a deficient ability to increase the number of phagocytosed bacteria. Normal and Salmonella-infected mice increased their phagocytic capacity when exposed to a high bacterial load. Antibody to Salmonella increased the phagocytic capacity of macrophages from Schistosoma-infected mice due to an increase in the number of bacteria phagocytosed but caused no modification in the number of macrophages engaged in phagocytosis. Our data indicate that macrophages from Schistosoma-infected mice work close to their functional limit, since no increase in phagocytosis was observed after increasing the bacterial load. Specific antibodies can improve their phagocytic capacity and, therefore, could help clearing concurrent infection.

  19. PCR multiplex for detection of Salmonella Enteritidis, Typhi and Typhimurium and occurrence in poultry meat.

    Science.gov (United States)

    de Freitas, Camila Guimarães; Santana, Angela Patrícia; da Silva, Patrícia Helena Caldeira; Gonçalves, Vítor Salvador Picão; Barros, Márcia de Aguiar Ferreira; Torres, Fernando Araripe Gonçalves; Murata, Luci Sayori; Perecmanis, Simone

    2010-04-30

    The occurrence of foodborne diseases is increasing throughout the world. Bacteria of the genus Salmonella are responsible for food poisoning and, in some cases, may be fatal. The aim of this study was to adapt the multiplex PCR technique (mPCR) on the rapid and direct identification of the presence of Salmonella sp. as well as serotypes Enteritidis, Typhi and Typhimurium in poultry carcasses (n=127) and viscera (n=73). The implementation of the standard technique using positive controls was successfully adapted. The results of Salmonella sp. detection in refrigerated viscera showed that the mPCR was able to detect Salmonella genus in 2.74% of these samples. Traditional microbiological analysis also identified the same positive samples for Salmonella sp. but was not able to differentiate the serotype. The serotype Enteritidis was detected by mPCR in 1.37% of the samples. Our conclusion was that the mPCR was able to detect the presence of these bacteria in a short period of time and enabled the identification of serotype Enteritidis in one of the samples found positive for Salmonella sp.

  20. Ciprofloxacin-resistant Salmonella enterica Typhimurium and Choleraesuis from pigs to humans, Taiwan.

    Science.gov (United States)

    Hsueh, Po-Ren; Teng, Lee-Jene; Tseng, Sung-Pin; Chang, Chao-Fu; Wan, Jen-Hsien; Yan, Jing-Jou; Lee, Chun-Ming; Chuang, Yin-Ching; Huang, Wen-Kuei; Yang, Dine; Shyr, Jainn-Ming; Yu, Kwok-Woon; Wang, Li-Shin; Lu, Jang-Jih; Ko, Wen-Chien; Wu, Jiunn-Jong; Chang, Feng-Yee; Yang, Yi-Chueh; Lau, Yeu-Jun; Liu, Yung-Ching; Liu, Cheng-Yi; Ho, Shen-Wu; Luh, Kwen-Tay

    2004-01-01

    We evaluated the disk susceptibility data of 671 nontyphoid Salmonella isolates collected from different parts of Taiwan from March 2001 to August 2001 and 1,261 nontyphoid Salmonella isolates from the National Taiwan University Hospital from 1996 to 2001. Overall, ciprofloxacin resistance was found in 2.7% (18/671) of all nontyphoid Salmonella isolates, in 1.4% (5/347) of Salmonella enterica serotype Typhimurium and in 7.5% (8/107) in S. enterica serotype Choleraesuis nationwide. MICs of six newer fluoroquinolones were determined for the following isolates: 37 isolates of ciprofloxacin-resistant (human) S. Typhimurium (N = 26) and Choleraesuis (N = 11), 10 isolates of ciprofloxacin-susceptible (MIC MIC >0.12 microg/mL). Sequence analysis of the gryA, gyrB, parC, parE, and acrR genes, ciprofloxacin accumulation, and genotypes generated by pulsed-field gel electrophoresis with three restriction enzymes (SpeI, XbaI, and BlnI) were performed. All 26 S. Typhimurium isolates from humans and pigs belonged to genotype I. For S. Choleraesuis isolates, 91% (10/11) of human isolates and 54% (7/13) of swine isolates belonged to genotype B. These two genotypes isolates from humans all exhibited a high-level of resistance to ciprofloxacin (MIC 16-64 mg/mL). They had two-base substitutions in the gyrA gene at codons 83 (Ser83Phe) and 87 (Asp87Gly or Asp87Asn) and in the parC gene at codon 80 (Ser80Arg, Ser80Ile, or Ser84Lys). Our investigation documented that not only did these two S. enterica isolates have a high prevalence of ciprofloxacin resistance nationwide but also that some closely related ciprofloxacin-resistant strains are disseminated from pigs to humans.

  1. The two murein lipoproteins of Salmonella enterica serovar Typhimurium contribute to the virulence of the organism.

    Science.gov (United States)

    Sha, J; Fadl, A A; Klimpel, G R; Niesel, D W; Popov, V L; Chopra, A K

    2004-07-01

    Septic shock due to Salmonella and other gram-negative enteric pathogens is a leading cause of death worldwide. The role of lipopolysaccharide in sepsis is well studied; however, the contribution of other bacterial outer membrane components, such as Braun (murein) lipoprotein (Lpp), is not well defined. The genome of Salmonella enterica serovar Typhimurium harbors two copies of the lipoprotein (lpp) gene. We constructed a serovar Typhimurium strain with deletions in both copies of the lpp gene (lpp1 and lpp2) by marker exchange mutagenesis. The integrity of the cell membrane and the secretion of the effector proteins through the type III secretion system were not affected in the lpp double-knockout mutant. Subsequently, the virulence potential of this mutant was examined in a cell culture system using T84 intestinal epithelial and RAW264.7 macrophage cell lines and a mouse model of salmonellosis. The lpp double-knockout mutant was defective in invading and inducing cytotoxic effects in T84 and RAW264.7 cells, although binding of the mutant to the host cell was not affected when compared to the wild-type (WT) serovar Typhimurium. The motility of the mutant was impaired, despite the finding that the number of flagella was similar in the lpp double knockout mutant and the WT serovar Typhimurium. Deletion in the lpp genes did not affect the intracellular survival and replication of Salmonella in macrophages and T84 cells. Induction of the proinflammatory cytokines tumor necrosis factor alpha and interleukin-8 (IL-8) was significantly reduced in macrophages and T84 cells infected with the lpp double-knockout mutant. The levels of IL-8 remained unaffected in T84 cells when infected with either live or heat-killed WT and lpp mutant, indicating that invasion was not required for IL-8 production and that Toll-like receptor 2 signaling might be affected in the Lpp double-knockout mutant. These effects of the Lpp protein could be restored by complementation of the isogenic

  2. Characterization of c-di-GMP signaling in Salmonella typhimurium

    OpenAIRE

    Simm, Roger

    2007-01-01

    Signal transduction via cyclic nucleotides is a general mechanism utilized by cells from all kingdoms of life. Identification of cyclic diguanosine monophosphate (c-di-GMP) as an allosteric activator of the cellulose synthase in Gluconacetobacter xylinus 20 years ago, paved the way for the discovery of a novel general signalling system which is unique to bacteria. In this thesis, the c-di-GMP signalling network leading to the formation of a biofilm behavior in Salmonella...

  3. Fatty acid modulation of autoinducer (AI-2) influenced growth and macrophage invasion by Salmonella Typhimurium.

    Science.gov (United States)

    Widmer, Kenneth W; Jesudhasan, Palmy; Pillai, Suresh D

    2012-03-01

    Autoinducer-2 (AI-2) is a small molecule that is involved in bacterial cell-to-cell signaling whose precursor formation is mediated by luxS. A luxS mutant of Salmonella Typhimurium PJ002 (ΔluxS) was grown in glucose-containing M-9 minimal medium supplemented with varying concentrations (1×, 10×, and 100×) of long-chain fatty acids (linoleic acid, oleic acid, palmitic acid, and stearic acid) to study the influence of fatty acids on growth rate and macrophage invasion. Additionally, in vitro synthesized AI-2 was added to this medium to identify the influence of AI-2 on S. Typhimurium PJ002 (ΔluxS) growth rate and macrophage invasion. The growth rate constant (k) for each experimental treatment was determined based on OD₆₀₀ values recorded during 12 h of incubation. There was a significant (p=0.01) increase in the growth rate of S. Typhimurium PJ002 (ΔluxS) in the presence of AI-2 when compared to the phosphate-buffered saline (PBS) control. However, fatty acids either singly or in a mixture were unable to influence AI-2's effect on growth rate. The presence of AI-2 significantly (p=0.02) decreased the invasiveness of S. Typhimurium PJ002 (ΔluxS) towards the murine macrophage cell line, RAW 264.7. However, the fatty acid mixture was able to reverse this reduction and restore invasiveness to background levels. These results suggest that, while AI-2 may enhance the growth rate and reduce macrophage invasion by the luxS mutant S. Typhimurium PJ002 (ΔluxS), fatty acids may influence the virulence in S. Typhimurium (PJ002) by modulating AI-2 activity.

  4. Salmonella Typhimurium type III secretion effectors stimulate innate immune responses in cultured epithelial cells.

    Directory of Open Access Journals (Sweden)

    Vincent M Bruno

    2009-08-01

    Full Text Available Recognition of conserved bacterial products by innate immune receptors leads to inflammatory responses that control pathogen spread but that can also result in pathology. Intestinal epithelial cells are exposed to bacterial products and therefore must prevent signaling through innate immune receptors to avoid pathology. However, enteric pathogens are able to stimulate intestinal inflammation. We show here that the enteric pathogen Salmonella Typhimurium can stimulate innate immune responses in cultured epithelial cells by mechanisms that do not involve receptors of the innate immune system. Instead, S. Typhimurium stimulates these responses by delivering through its type III secretion system the bacterial effector proteins SopE, SopE2, and SopB, which in a redundant fashion stimulate Rho-family GTPases leading to the activation of mitogen-activated protein (MAP kinase and NF-kappaB signaling. These observations have implications for the understanding of the mechanisms by which Salmonella Typhimurium induces intestinal inflammation as well as other intestinal inflammatory pathologies.

  5. Production of Diamino propionic acid ammonia lyase by a new strain of Salmonella typhimurium PU011

    Directory of Open Access Journals (Sweden)

    Shiva Kumar Vasanth V

    2002-03-01

    Full Text Available Abstract Background Seeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP. DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP. Results S. typhimurium PU011, a non-virulent bacterial strain isolated in our lab, was found to produce DAP ammonia lyase enzyme when grown in minimal medium containing DAP. There was a direct correlation between biomass yield and enzyme activity, until 16 h post inoculation in minimal medium containing DAP. Following ammonium sulphate precipitation and passing through Sephadex G100, CM-Sephadex and DEAE-Sephacel for crude enzyme extract preparation, about 68-fold enzyme purity was obtained. The purified enzyme gave maximum activity at pH 8.0 and was stable up to 45 degrees C. The Km value for the substrate was found to be 0.685mM, calculated from a Line Weaver Burk plot. Conclusion A new bacterial strain, S.typhimurium PU 011, which is capable of producing DAP ammonia lyase, was isolated.

  6. Expression of Human Sperm Membrane Protein in the Recombinant Salmonella Typhimurium Vaccine

    Institute of Scientific and Technical Information of China (English)

    匡颖; 胡菁华; 翟玉梅; 缨时英; 王琳芳; 严缘昌

    1999-01-01

    A 550 bp cDNA fragment of HSD-Ⅰ coding for an extracellular domain of hu-man sperm membrane protein(hSMP-1)was ligated with an Adapter containing the universal stop codon,and the ligated fragment cDNA was then cloned into the MAS of pUC19.The desired plasmid with correct open reading frame was obtained, and was cut with EcoR Ⅰ.The insert was purified and then cloned into the two asd+ Salmonella expression vectors(the low copy number plasmid-pYA292 and the high copy number plasmid-pYA3137).The recombinant plasmid containing the insert with the correct orientation was selected by restriction enzyme digestion analysis. The recom-binant plasmids were transferred into the non-pathogenic Salmonella typhimurium X4550,which was deletion of the △cya, △crp and △asd genes.Western-blot analysis of the whole cell lysate of the two recombinants of S.typhimurium showed a predomi-nant protein band at 21 KD,which reacted with the anti-hSMP-1 antiserum. The re-sult indicated that two recombinants of S.typhimurium containing the 550 bp cDNA of HSD-Ⅰ were constructed and the characteristics of their growth in vitro were deter-mined. They may be used as new potential mucosalanti fertility.

  7. Risk factors for clinical Salmonella enterica subsp. enterica serovar Typhimurium infection on Dutch dairy farms.

    Science.gov (United States)

    Veling, J; Wilpshaar, H; Frankena, K; Bartels, C; Barkema, H W

    2002-06-25

    Risk factors for outbreaks in 1999 of clinical Salmonella enterica subsp. enterica serovar Typhimurium infection on dairy farms were studied in a matched case-control study with 47 case farms and 47 control farms. All 47 case farms experienced a clinical outbreak of salmonellosis which was confirmed with a positive bacteriologic culture for serovar Typhimurium in one or more samples. Serovar Typhimurium phage type 401 and 506 (definitive type 104, DT104) were the most frequently isolated phage types (13 isolates). On most farms (66%), clinical signs were seen only among adult cows. The most frequently reported clinical signs were diarrhoea (in 92% of the farms) and depression (in 79% of the farms). Control farms were matched on region and had no history of salmonellosis. A questionnaire was used to collect data on case and control farms. The relationship between serovar Typhimurium status of the farm and possible risk factors was tested using conditional logistic regression. Significant factors in the final model were presence of cats on the farm (OR=0.06), purchase of manure (OR=21.5), feeding colostrum only from own dam (OR=0.08), a non-seasonal calving pattern (OR=25), unrestricted grazing of lactating cows (OR=0.07), and a high mean mowing percentage of pasture (OR=1.02).

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. Anti-tumoral effect of the mitochondrial target domain of Noxa delivered by an engineered Salmonella typhimurium.

    Directory of Open Access Journals (Sweden)

    Jae-Ho Jeong

    Full Text Available Bacterial cancer therapy relies on the fact that several bacterial species are capable of targeting tumor tissue and that bacteria can be genetically engineered to selectively deliver therapeutic proteins of interest to the targeted tumors. However, the challenge of bacterial cancer therapy is the release of the therapeutic proteins from the bacteria and entry of the proteins into tumor cells. This study employed an attenuated Salmonella typhimurium to selectively deliver the mitochondrial targeting domain of Noxa (MTD as a potential therapeutic cargo protein, and examined its anti-cancer effect. To release MTD from the bacteria, a novel bacterial lysis system of phage origin was deployed. To facilitate the entry of MTD into the tumor cells, the MTD was fused to DS4.3, a novel cell-penetrating peptide (CPP derived from a voltage-gated potassium channel (Kv2.1. The gene encoding DS4.3-MTD and the phage lysis genes were placed under the control of PBAD , a promoter activated by L-arabinose. We demonstrated that DS4.3-MTD chimeric molecules expressed by the Salmonellae were anti-tumoral in cultured tumor cells and in mice with CT26 colon carcinoma.

  11. Tackling the issue of environmental survival of live Salmonella Typhimurium vaccines: deletion of the lon gene.

    Science.gov (United States)

    Leyman, Bregje; Boyen, Filip; Van Parys, Alexander; Verbrugghe, Elin; Haesebrouck, Freddy; Pasmans, Frank

    2012-12-01

    Vaccination is an important measure to control Salmonella contamination in the meat production chain. A previous study showed that both the ΔrfaJ and ΔrfaL strains are suitable markers and allow serological differentiation of infected and vaccinated animals. The aim of this study was to verify whether deletion of the lon gene in a Salmonella Typhimurium ΔrfaJ marker strain resulted in decreased environmental survival. Our results indicate that deletion of the lon gene in the ΔrfaJ strain did not affect invasiveness in IPEC-J2 cells and resulted in an increased susceptibility to UV, disinfectants (such as hydrogen peroxide and tosylchloramide sodium) and citric acid. Immunization of pigs with inactivated ΔrfaJ or ΔlonΔrfaJ vaccines allowed differentiation of infected and vaccinated pigs. Furthermore, deletion of the lon gene did not reduce the protection conferred by live wild type or ΔrfaJ vaccines against subsequent challenge with a virulent Salmonella Typhimurium strain in BALB/c mice. Based on our results in mice, we conclude that deletion of lon in ΔrfaJ contributes to environmental safety of the ΔrfaJ DIVA strain.

  12. Development of ceftriaxone resistance affects the virulence properties of Salmonella enterica serotype Typhimurium strains.

    Science.gov (United States)

    Li, Liang; Yang, Yu-Rong; Liao, Xiao-Ping; Lei, Chun-Yin; Sun, Jian; Li, Lu-Lu; Liu, Bao-Tao; Yang, Shou-Shen; Liu, Ya-Hong

    2013-01-01

    Development of antibiotic resistance may alter the virulence properties of bacterial organisms. In this study, nine clinical ceftriaxone-susceptible Salmonella enterica serotype Typhimurium strains were subjected to stepwise selection with increasing concentrations of ceftriaxone in culture media. Mutations in virulence-associated genes and antibiotic efflux genes were analyzed by polymerase chain reaction (PCR) and DNA sequencing. The expression levels of virulence genes invA and stn as well as efflux pump genes tolC, arcA, and arcB before and after the selection were measured by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The stepwise selection resulted in the development of Salmonella strains that were highly resistant to ceftriaxone. Sequence analysis did not reveal any mutations or deletions in the examined virulence genes and regulatory gene, but a silent mutation (T423C) in acrR (encoding a repressor for the efflux pump) was detected in most of the ceftriaxone-resistant strains. The qRT-PCR revealed increased expression of the AcrAB-TolC efflux pump and decreased expression of invA and stn in the ceftriaxone-resistant strains. Moreover, decreased invasion into cultured epithelial cells and reduced growth rates were observed with the resistant strains. These results suggest that acquisition of ceftriaxone resistance is associated with the overexpression of the AcrAB-TolC efflux pump and leads to reduced virulence in Salmonella Typhimurium.

  13. Development of a new nomenclature for Salmonella Typhimurium multilocus variable number of tandem repeats analysis (MLVA)

    DEFF Research Database (Denmark)

    Larsson, JT; Torpdahl, M; Petersen, RF;

    2009-01-01

    Multilocus variable number of tandem repeats analysis (MLVA) has recently become a widely used highly discriminatory molecular method for typing of the foodborne pathogen Salmonella Typhimurium. This method is based on amplification and fragment size analysis of five repeat loci. To be able...... to easily compare MLVA results between laboratories there is a need for a simple and definitive nomenclature for MLVA profiles. Based on MLVA results for all human S. Typhimurium isolates in Denmark from the last five years and sequence analysis of a selection of these isolates, we propose a MLVA...... nomenclature that indicates the actual number of repeat units in each locus. This nomenclature is independent of the equipment used for fragment analysis and, in principle, independent of the primers used. A set of reference strains is developed that can be used for easy normalisation of fragment sizes in each...

  14. Structure of Salmonella typhimurium OMP Synthase in a Complete Substrate Complex

    DEFF Research Database (Denmark)

    Grubmeyer, Charles; Hansen, Michael Riis; Fedorov, Alexander A.

    2012-01-01

    Dimeric Salmonella typhimurium orotate phosphoribosyltransferase (OMP synthase, EC 2.4.2.10), a key enzyme in de novo pyrimidine nucleotide synthesis, has been cocrystallized in a complete substrate E·MgPRPP·orotate complex and the structure determined to 2.2 Å resolution. This structure...... resembles that of Saccharomyces cerevisiae OMP synthase in showing a dramatic and asymmetric reorganization around the active site-bound ligands but shares the same basic topology previously observed in complexes of OMP synthase from S. typhimurium and Escherichia coli. The catalytic loop (residues 99......?109) contributed by subunit A is reorganized to close the active site situated in subunit B and to sequester it from solvent. Furthermore, the overall structure of subunit B is more compact, because of movements of the amino-terminal hood and elements of the core domain. The catalytic loop of subunit B remains...

  15. Antimicrobial resistance in Salmonella enterica subsp. enterica serovar typhimurium from humans and production animals

    DEFF Research Database (Denmark)

    Seyfarth, Anne Mette; Wegener, Henrik Caspar; FrimodtMoller, N.

    1997-01-01

    to the State Serum Institute during August 1993 (228 isolates). The animal strains were isolated from clinical or subclinical infections in cattle (48 isolates), pigs (99 isolates) or poultry (98 isolates), all from 1993. All strains were tested against 22 different antimicrobial agents used in both human......: Poultry strains were usually resistant only to ampicillin, white pig and cattle isolates were most often resistant to sulphonamide, tetracycline and streptomycin. Typing of the strains showed that some animal strains and human strains were indistinguishable. In conclusion, while antimicrobial resistance......We have studied the frequency of antimicrobial resistance and epidemiological relatedness among 473 isolates of Salmonella enterica subsp, enterica serovar typhimurium (S. typhimurium) from human and veterinary sources. The human strains were clinical isolates from patients with diarrhoea sent...

  16. Evolution of Variable Number Tandem Repeats and Its Relationship with Genomic Diversity in Salmonella Typhimurium

    Science.gov (United States)

    Fu, Songzhe; Octavia, Sophie; Wang, Qinning; Tanaka, Mark M.; Tay, Chin Yen; Sintchenko, Vitali; Lan, Ruiting

    2016-01-01

    Salmonella enterica serovar Typhimurium is the most common Salmonella serovar causing human infections in Australia and many other countries. A total of 12,112 S. Typhimurium isolates from New South Wales were analyzed by multi-locus variable number of tandem repeat (VNTR) analysis (MLVA) using five VNTRs from 2007 to 2014. We found that mid ranges of repeat units of 8–14 in VNTR locus STTR5, 6–13 in STTR6, and 9–12 in STTR10 were always predominant in the population (>50%). In vitro passaging experiments using MLVA type carrying extreme length alleles found that the majority of long length alleles mutated to short ones and short length alleles mutated to longer ones. Both data suggest directional mutability of VNTRs toward mid-range repeats. Sequencing of 28 isolates from a newly emerged MLVA type and its five single locus variants revealed that single nucleotide variation between isolates with up to two MLVA differences ranged from 0 to 12 single nucleotide polymorphisms (SNPs). However, there was no relationship between SNP and VNTR differences. A population genetic model of the joint distribution of VNTRs and SNPs variations was used to estimate the mutation rates of the two markers, yielding a ratio of 1 VNTR change to 6.9 SNP changes. When only one VNTR repeat difference was considered, the majority of pairwise SNP difference between isolates were 4 SNPs or fewer. Based on this observation and our previous findings of SNP differences of outbreak isolates, we suggest that investigation of S. Typhimurium community outbreaks should include cases of 1 repeat difference to increase sensitivity. This study offers new insights into the short-term VNTR evolution of S. Typhimurium and its application for epidemiological typing. PMID:28082952

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  19. Interactions between Salmonella typhimurium and Acanthamoeba polyphaga, and observation of a new mode of intracellular growth within contractile vacuoles.

    Science.gov (United States)

    Gaze, W H; Burroughs, N; Gallagher, M P; Wellington, E M H

    2003-10-01

    Acanthamoeba polyphaga feeding on Salmonella typhimurium in a simple model biofilm were observed by light microscopy and a detailed record of interactions kept by digital image capture and image analysis. A strain of S. typhimurium SL1344 carrying a fis: gfp reporter construct (pPDT105) was used to assess intracellular growth in A. polyphaga on non-nutrient agar (NNA) plates. Invasion of the contractile vacuole (CV) was observed at a frequency of 1:100-1000 acanthamoebae at 35 degrees C. The salmonellae contained in CVs illustrated significant up-regulation of fis relative to extracellular bacteria, indicating that they were in the early stages of logarithmic growth, and reached numbers of 100-200 cells per vacuole after 4 days. This is the first report of this mode of intracellular growth. Up-regulation of fis was also observed in a proportion of S. typhimurium cells contained within food vacuoles. Filamentation of S. typhimurium and E. coli cells was frequently observed in coculture with A. polyphaga on NNA plates, with bacterial cells reaching lengths of up to 500 microm after 10 days' incubation at 35 degrees C. A. polyphaga was also seen to mediate bacterial translocation over the agar surface; egested salmonellae subsequently formed microcolonies along amoebal tracks. This illustrated intracellular survival of a fraction of the S. typhimurium population. These phenomena suggest that protozoa such as A. polyhaga may play an important role in the ecology of S. typhimurium in soil and aquatic environments.

  20. 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.

    Science.gov (United States)

    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

  1. DETERMINACIÓN DE Salmonella Typhimurium EN COMPOST INOCULADO ARTIFICIALMENTE EMPLEADO EN UN CULTIVO DE LECHUGA

    Directory of Open Access Journals (Sweden)

    DIANA MARCELA RODRÍGUEZ

    2008-01-01

    Full Text Available Salmonella enterica serovariedad Typhimurium, se ha asociado a brotes por el consumo de frutas y vegetales contaminadas a partir de agua de riego, manipuladores, bioabono y suelo. En esta investigación se inoculó artificialmente un bioabono aplicado a un cultivo de lechuga para determinar la capacidad de transferencia a las plantas, así como establecer el efecto del uso de cubiertas de polietileno en la protección del cultivo frente a este patógeno. Para ello, se utilizaron plántulas de lechuga de ocho semanas y se establecieron cuatro tratamientos y dos controles: T1 y T2, con y sin cubierta de polietileno respectivamente, contenían una concentración de Salmonella enterica Serovariedad Typhimurium ATCC 13176 inoculada en el compost en concentración de 0,04 mo/g, T3 y T4 con y sin cubierta de polietileno respectivamente con 100 mo/g de compost y finalmente C1 y C2 con y sin cubierta pero sin inoculación. El seguimiento del microorganismo en suelo se realizó durante las ocho semanas del cultivo, mediante la técnica de NMP/4 g (EPA, 2006 al cabo de este tiempo se evaluó el total de plantas cultivadas mediante la misma técnica. Se determinó que Salmonella enterica serovariedad Typhimurium ATCC 13176 se transmite a la lechuga, a partir del bioabono contaminado (OR=2,53 sin importar la concentración inicial del microorganismo en el bioabono; así mismo se encontró que existe asociación entre la contaminación y la condición de cubierta del cultivo (p=0,002. Por otra parte, al analizar las raíces no se encontró asociación de transmisión.

  2. DETERMINACIÓN DE Salmonella Typhimurium EN COMPOST INOCULADO ARTIFICIALMENTE EMPLEADO EN UN CULTIVO DE LECHUGA

    Directory of Open Access Journals (Sweden)

    Martinez Maria Mercedes

    2008-12-01

    Full Text Available Salmonella enterica serovariedad Typhimurium, se ha asociado a brotes por el consumo de frutas y vegetales contaminadas a partir de agua de riego, manipuladores, bioabono y suelo. En esta investigación se inoculó artificialmente un bioabono aplicado a un cultivo de lechuga para determinar la capacidad de transferencia a las plantas, así como establecer el efecto del uso de cubiertas de polietileno en la protección del cultivo frente a este patógeno. Para ello, se utilizaron plántulas de lechuga de ocho semanas y se establecieron cuatro tratamientos y dos controles: T1 y T2, con y sin cubierta de polietileno respectivamente, contenían una concentración de Salmonella enterica Serovariedad Typhimurium ATCC 13176 inoculada en el compost en concentración de 0,04 mo/g, T3 y T4 con y sin cubierta de polietileno respectivamente con 100 mo/g de compost y finalmente C1 y C2 con y sin cubierta pero sin inoculación. El seguimiento del microorganismo en suelo se realizó durante las ocho semanas del cultivo, mediante la técnica de NMP/4 g (EPA, 2006 al cabo de este tiempo se evaluó el total de plantas cultivadas mediante la misma técnica. Se determinó que Salmonella enterica serovariedad Typhimurium ATCC 13176 se transmite a la lechuga, a partir del bioabono contaminado (OR=2,53 sin importar la concentración inicial del microorganismo en el bioabono; así mismo se encontró que existe asociación entre la contaminación y la condición de cubierta del cultivo (p=0,002. Por otra parte, al analizar las raíces no se encontró asociación de transmisión.

  3. ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR SCREENING OF MILK SAMPLES FOR SALMONELLA-TYPHIMURIUM IN DAIRY HERDS

    DEFF Research Database (Denmark)

    Hoorfar, Jeffrey; Wedderkopp, A.

    1995-01-01

    positive (herd specificity, 0.9 and herd sensitivity, 1.0). A sig nificant correlation (P serum and milk samples from cows in the herds with a history of salmonellosis. It was concluded that ELISA testing of individual milk sam ples can be used for surveillance......We investigated the ability of an antibody-specific, O antigen-based ELISA to document Salmonella typhimurium herd infections by screening of milk samples. Three cattle populations, 20 herds with no history of salmonellosis, 8 herds with history of S typhimurium epsiodes within the previous 7...... of herds for S typhimurium infections, but further modifications are needed to test bulk tank milk samples....

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

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yun-Hee [Department of Food Science and Technology, College of Agriculture and Life Science, Chungnam National University, Yuseong-Gu, Daejeon 305-764 (Korea, Republic of); Park, Ji-Yong [Department of Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Jong-Hyun [Department of Food Science and Biotechnology, Kyungwon University, Sungnam 461-701 (Korea, Republic of); Chung, Myong-Soo [Department of Food Science, Ehwa Women' s University, Seoul 120-750 (Korea, Republic of); Kwon, Ki-Sung [Center for Food safety Evaluation, Korea Food and Drug Administration, Seoul 122-704 (Korea, Republic of); Chung, Kyungsook; Won, Misun [Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-333 (Korea, Republic of); Song, Kyung-Bin [Department of Food Science and Technology, College of Agriculture and Life Science, Chungnam National University, Yuseong-Gu, Daejeon 305-764 (Korea, Republic of)], E-mail: kbsong@cnu.ac.kr

    2008-09-15

    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 D{sub 10}-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.

  5. High Prevalence of Extended-Spectrum Beta Lactamases among Salmonella enterica Typhimurium Isolates from Pediatric Patients with Diarrhea in China

    Science.gov (United States)

    Yu, Fangyou; Chen, Qiang; Yu, Xiaojun; Li, Qiaoqiao; Ding, Baixing; Yang, Lehe; Chen, Cong; Qin, Zhiqiang; Parsons, Chris; Zhang, Xueqing; Huang, Jinwei; Luo, Yun; Wang, Liangxing; Pan, Jingye

    2011-01-01

    We investigated the extended-spectrum beta lactamases among 62 Salmonella enterica Typhimurium isolates recovered from children with diarrhea in a Chinese pediatric hospital. A large proportion of S. enterica Typhimurium isolates were resistant to multiple antimicrobial agents, including ampicillin (90.3%), tetracycline (80.6%), trimethoprim/sulfamethoxazole (74.2%), chloramphenicol (66.1%), cefotaxime (27.4%). Forty-nine (79.0%) of S. enterica Typhimurium isolates were positive for blaTEM-1b and resistant to ampicillin. Thirteen S. enterica Typhimurium isolates (21.0%) were positive for blaCTX-M-1-group and blaCTX-M-9-group, and all isolates harboring blaCTX-M genes were positive for ISEcp1. Two main clones (PFGE type A and D) accounted for nearly 70% of S. enterica Typhimurium isolates, and 7 CTX-M-producing isolates belonged to PFGE type D. Collectively, our data reveal multi-drug resistance and a high prevalence of extended spectrum beta lactamases among S. enterica Typhimurium isolates from children in China. In addition, we report the first identification of blaCTX-M-55 within Salmonella spp. Our data also suggest that clonal spread is responsible for the dissemination of S. enterica Typhimurium isolates. PMID:21390297

  6. High prevalence of extended-spectrum beta lactamases among Salmonella enterica Typhimurium isolates from pediatric patients with diarrhea in China.

    Directory of Open Access Journals (Sweden)

    Fangyou Yu

    Full Text Available We investigated the extended-spectrum beta lactamases among 62 Salmonella enterica Typhimurium isolates recovered from children with diarrhea in a Chinese pediatric hospital. A large proportion of S. enterica Typhimurium isolates were resistant to multiple antimicrobial agents, including ampicillin (90.3%, tetracycline (80.6%, trimethoprim/sulfamethoxazole (74.2%, chloramphenicol (66.1%, cefotaxime (27.4%. Forty-nine (79.0% of S. enterica Typhimurium isolates were positive for bla(TEM-1b and resistant to ampicillin. Thirteen S. enterica Typhimurium isolates (21.0% were positive for bla(CTX-M-1-group and bla(CTX-M-9-group, and all isolates harboring bla(CTX-M genes were positive for ISEcp1. Two main clones (PFGE type A and D accounted for nearly 70% of S. enterica Typhimurium isolates, and 7 CTX-M-producing isolates belonged to PFGE type D. Collectively, our data reveal multi-drug resistance and a high prevalence of extended spectrum beta lactamases among S. enterica Typhimurium isolates from children in China. In addition, we report the first identification of bla(CTX-M-55 within Salmonella spp. Our data also suggest that clonal spread is responsible for the dissemination of S. enterica Typhimurium isolates.

  7. An outbreak of Salmonella serotype Typhimurium infections with an unusually long incubation period.

    Science.gov (United States)

    Brooks, John T; Matyas, Bela T; Fontana, John; DeGroot, Mary Ann; Beuchat, Larry R; Hoekstra, Michael; Friedman, Cindy R

    2012-03-01

    A 1998 investigation of an outbreak of Salmonella serotype Typhimurium infections among children tasting unpasteurized milk during tours of a dairy farm demonstrated a distribution of unusually long incubation periods (median, 8 days; interquartile range [IQR], 6-14 days). Bacterial isolates were highly acid tolerant and contained genes associated with protection against destructive phagocytic reactive oxygen intermediates. We hypothesize that exposure to low-dose oral inoculum of a pathogen with these properties could have contributed to cases of non-typhoidal salmonellosis with the longest incubation period reported to the Centers for Disease Control and Prevention (CDC).

  8. [A ruptured mycotic aneurysm of the femoral artery due to Salmonella typhimurium].

    Science.gov (United States)

    Calvo Cascallo, J; Mundi Salvadó, N; Cardona Fontanet, M

    1993-01-01

    Mycotic aneurysms of the femoral artery is rare. We report a new case with a mycotic aneurysm of the femoral artery by "Salmonella typhimurium". The surgical operation was performed as surgical emergence for ruptured aneurysm. We did not know the aneurysm infection origin. The treatment of lesions was resection and femoro-femoral bypass with PTFE. The microbiological examination discovered infection material. A posterior bypass infection required a exeresis bypass and new revascularization with iliofemoral saphenous vein bypass by obturator foramen, and antibiotic treatment prolonged.

  9. Salmonella Typhimurium undergoes distinct genetic adaption during chronic infections of mice

    DEFF Research Database (Denmark)

    Søndberg, Emilie; Jelsbak, Lotte

    2016-01-01

    Background Typhoid fever caused by Salmonella enterica serovar Typhi (S. Typhi) is a severe systemic human disease and endemic in regions of the world with poor drinking water quality and sewage treatment facilities. A significant number of patients become asymptomatic life-long carriers of S....... In the current study genetic adaptation during experimental chronic S. Typhimurium infections of mice, an established model of chronic typhoid fever, was probed as an approach for studying the molecular mechanisms of host-adaptation during long-term host-association. Results Individually sequence-tagged wild...

  10. Salmonella Typhimurium undergoes distinct genetic adaption during chronic infections of mice

    DEFF Research Database (Denmark)

    Søndberg, Emilie; Jelsbak, Lotte

    2016-01-01

    Background Typhoid fever caused by Salmonella enterica serovar Typhi (S. Typhi) is a severe systemic human disease and endemic in regions of the world with poor drinking water quality and sewage treatment facilities. A significant number of patients become asymptomatic life-long carriers of S......, the kdgR-SNP was confirmed to confer selective advantage during chronic infections and constitute a true patho-adaptive mutation. Together, the results provide evidence for rapid genetic adaptation to the host of S. Typhimurium and validate experimental evolution in the context of host infection...

  11. [Immunosuppressive components of extracellular lipopolysaccharide highly virulent strain Salmonella typhimurium 1468].

    Science.gov (United States)

    Molozhavaia, O S; Borisova, E V

    2002-01-01

    Immunosuppressive activity of culture liquid substrate (CFS) of highly virulent strain Salmonella typhimurium has been studied. A model of delayed hypersensitivity (DHS) to nonbacterial antigen in mice, a method of gel-filtration through the sephadex column G-200, immunosorbents were used. Three components with immunosuppressive activity: thermolabile component and thermostable one with direct immunosuppressive action and the third thermolabile component which manifested inductive immunosuppressive activity only after redox treatment have been revealed in the strain CFS. O-specific and lipid parts were found in the composition of all the components. This allowed them to be related to lipopolysaccharide.

  12. Absence of mutagenic activity of trifluoroethanol and its metabolites in Salmonella typhimurium.

    Science.gov (United States)

    Blake, D A; DiBlasi, M C; Gordon, G B

    1981-01-01

    Trifluoroethanol, trifluoroacetaldehyde and trifluoroacetate were found to have no mutagenic activity in the standard Salmonella typhimurium reverse mutation assay (Ames test) using a closed incubation system. Negative results were also obtained when incubation mixtures included 9000 x g supernatant fractions of rat liver or testes homogenates along with an NADPH generating system. Rats were pretreated with a polychlorinated biphenyl mixture to induce biotransforming enzyme activity. These results suggest that the previously reported mutagenic activity of fluroxene is not due to metabolites arising from the trifluoroethyl side of the molecule and that inhibition of spermatogenesis in rats by trifluoroethanol is not mediated through a mutagenic mechanism.

  13. Some putative prebiotics increase the severity of Salmonella enterica serovar Typhimurium infection in mice

    DEFF Research Database (Denmark)

    Petersen, Anne; Heegaard, Peter M. H.; Pedersen, Anna Lovmand

    2009-01-01

    Prebiotics are non-digestible food ingredients believed to beneficially affect host health by selectively stimulating the growth of the beneficial bacteria residing in the gut. Such beneficial bacteria have been reported to protect against pathogenic infections. However, contradicting results...... on prevention of Salmonella infections with prebiotics have been published. The aim of the present study was to examine whether S. Typhimurium SL1344 infection in mice could be prevented by administration of dietary carbohydrates with different structures and digestibility profiles. BALB/c mice were fed a diet...

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

    Science.gov (United States)

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

    2014-08-06

    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.

  15. Characterization of Salmonella Typhimurium DNA gyrase as a target of quinolones.

    Science.gov (United States)

    Kongsoi, Siriporn; Yokoyama, Kazumasa; Suprasert, Apinun; Utrarachkij, Fuangfa; Nakajima, Chie; Suthienkul, Orasa; Suzuki, Yasuhiko

    2015-08-01

    Quinolones exhibit good antibacterial activity against Salmonella spp. isolates and are often the choice of treatment for life-threatening salmonellosis due to multi-drug resistant strains. To assess the properties of quinolones, we performed an in vitro assay to study the antibacterial activities of quinolones against recombinant DNA gyrase. We expressed the S. Typhimurium DNA gyrase A (GyrA) and B (GyrB) subunits in Escherichia coli. GyrA and GyrB were obtained at high purity (>95%) by nickel-nitrilotriacetic acid agarose resin column chromatography as His-tagged 97-kDa and 89-kDa proteins, respectively. Both subunits were shown to reconstitute an ATP-dependent DNA supercoiling activity. Drug concentrations that suppressed DNA supercoiling by 50% (IC50 s) or generated DNA cleavage by 25% (CC25 s) demonstrated that quinolones highly active against S. Typhimurium DNA gyrase share a fluorine atom at C-6. The relationships between the minimum inhibitory concentrations (MICs), IC50 s and CC25 s were assessed by estimating a linear regression between two components. MICs measured against S. Typhimurium NBRC 13245 correlated better with IC50 s (R = 0.9988) than CC25 s (R = 0.9685). These findings suggest that the DNA supercoiling inhibition assay may be a useful screening test to identify quinolones with promising activity against S. Typhimurium. The quinolone structure-activity relationship demonstrated here shows that C-8, the C-7 ring, the C-6 fluorine, and N-1 cyclopropyl substituents are desirable structural features in targeting S. Typhimurium gyrase.

  16. Growth and virulence properties of biofilm-forming Salmonella enterica serovar typhimurium under different acidic conditions.

    Science.gov (United States)

    Xu, Hua; Lee, Hyeon-Yong; Ahn, Juhee

    2010-12-01

    This study was designed to characterize the viability and potential virulence of bofilm-forming Salmonella enterica serovar Typhimurium under different pH levels, ranging from 5 to 7. The plate count method and real-time reverse transcription-PCR (RT-PCR) were used to evaluate the survival of S. Typhimurium grown in Trypticase soy broth (TSB) adjusted to pH 5, 6, and 7 (TSB-5, TSB-6, and TSB-7, respectively) at 37°C for 10 days. In TSB-5 and TSB-6, the numbers of viable cells estimated by using the real-time RT-PCR were greater than the culturable counts enumerated by the plate count method. Reflectance micro-Fourier transform infrared (micro-FTIR) spectroscopy was used to evaluate the biochemical changes in biofilm cells. Considerable changes in chemical components were observed in the biofilm cells grown in TSB-5 and TSB-6 when compared to the cells grown in TSB-7. The enterotoxin production and invasive ability of planktonic and biofilm S. Typhimurium cells were inferred by the relative levels of expression of stn and invA. The levels of expression of stn and invA were significantly increased in biofilm S. Typhimurium cells grown in TSB-5 (1.9-fold and 3.2-fold) and TSB-6 (2.1-fold and 22.3-fold) after 10 days of incubation. These results suggest that the biofilm-forming S. Typhimurium under different pH levels might change the virulence production and stress response mechanisms.

  17. Eradication of Salmonella Typhimurium in broiler chicks by combined use of P22 bacteriophage and probiotic

    Directory of Open Access Journals (Sweden)

    Guilherme Augusto Marietto Gonçalves

    2011-06-01

    Full Text Available It has been reported that the phage therapy is effective in controlling the number of colony-forming unit (CFU of Salmonella spp. in chicken gut. This paper describes the protective effect of phage and Lactobacilli administration on Salmonella infection in 1-day-old chicks. We administered the bacteriophage P22 in a single dose and a probiotic mixture of four species of bacteriocin-producing Lactobacillus once a day for one week. Samples were analyzed every 48 hours, and intestinal eradication of S. Typhimurium was confirmed after treatments. We observed an increase in the size of duodenal villi and cecal crypts, as well as an increase in body weight in groups that received daily doses of Lactobacilli. This study confirms the efficiency of bacteriophage therapy in controlling salmonellosis in chicks and the beneficial effect of Lactobacilli mixtures in the weight gain of the birds.

  18. Salmonella Typhimurium, Infantis, Derby, and Enteritidis survival in pasty dulce de leche

    Directory of Open Access Journals (Sweden)

    Débora Rodrigues da Silveira

    2012-12-01

    Full Text Available Dulce de leche is a food obtained by concentration and heating of milk with the addition of sucrose. The common practice of opening the dulce de leche containers in retail markets can lead to food contamination by Salmonella. The objective of this study was to evaluate the survivability of Salmonellaenterica subsp. enterica serotypes Typhimurium, Enteritidis, Infantis and Derby in pasty dulce de leche. Aliquots of this sweet were experimentally contaminated with these microorganisms and later analyzed to evaluate microorganism viability after storage for 0, 1, 2, 3, 5, 10, and 20 days. Salmonella was recovered up to the 20th day. These results are a warning about the need to adopt proper sanitary-hygienic measures for handling and packaging this food aiming at food safety.

  19. Discovery of novel secreted virulence factors from Salmonella enterica serovar Typhimurium by proteomic analysis of culture supernatants.

    Science.gov (United States)

    Niemann, George S; Brown, Roslyn N; Gustin, Jean K; Stufkens, Afke; Shaikh-Kidwai, Afshan S; Li, Jie; McDermott, Jason E; Brewer, Heather M; Schepmoes, Athena; Smith, Richard D; Adkins, Joshua N; Heffron, Fred

    2011-01-01

    Salmonella enterica serovar Typhimurium is a leading cause of acute gastroenteritis throughout the world. This pathogen has two type III secretion systems (TTSS) encoded in Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) that deliver virulence factors (effectors) to the host cell cytoplasm and are required for virulence. While many effectors have been identified and at least partially characterized, the full repertoire of effectors has not been catalogued. In this proteomic study, we identified effector proteins secreted into defined minimal medium designed to induce expression of the SPI-2 TTSS and its effectors. We compared the secretomes of the parent strain to those of strains missing essential (ssaK::cat) or regulatory (ΔssaL) components of the SPI-2 TTSS. We identified 20 known SPI-2 effectors. Excluding the translocon components SseBCD, all SPI-2 effectors were biased for identification in the ΔssaL mutant, substantiating the regulatory role of SsaL in TTS. To identify novel effector proteins, we coupled our secretome data with a machine learning algorithm (SIEVE, SVM-based identification and evaluation of virulence effectors) and selected 12 candidate proteins for further characterization. Using CyaA' reporter fusions, we identified six novel type III effectors and two additional proteins that were secreted into J774 macrophages independently of a TTSS. To assess their roles in virulence, we constructed nonpolar deletions and performed a competitive index analysis from intraperitoneally infected 129/SvJ mice. Six mutants were significantly attenuated for spleen colonization. Our results also suggest that non-type III secretion mechanisms are required for full Salmonella virulence.

  20. Evaluation of regulated delayed attenuation strategies for Salmonella enterica serovar Typhi vaccine vectors in neonatal and infant mice.

    Science.gov (United States)

    Shi, Huoying; Wang, Shifeng; Curtiss, Roy

    2013-06-01

    We developed regulated delayed attenuation strategies for Salmonella vaccine vectors. In this study, we evaluated the combination of these strategies in recombinant attenuated Salmonella enterica serovar Typhi and Salmonella enterica serovar Typhimurium vaccine vectors with similar genetic backgrounds in vitro and in vivo. Our goal is to develop a vaccine to prevent Streptococcus pneumoniae infection in newborns; thus, all strains delivered a pneumococcal antigen PspA and the impact of maternal antibodies was evaluated. The results showed that all strains with the regulated delayed attenuated phenotype (RDAP) displayed an invasive ability stronger than that of the S. Typhi vaccine strain, Ty21a, but weaker than that of their corresponding wild-type parental strains. The survival curves of different RDAP vaccine vectors in vitro and in vivo exhibited diverse regulated delayed attenuation kinetics, which was different from S. Typhi Ty21a and the wild-type parental strains. Under the influence of maternal antibody, the persistence of the S. Typhimurium RDAP strain displayed a regulated delayed attenuation trend in nasal lymphoid tissue (NALT), lung, and Peyer's patches, while the persistence of S. Typhi RDAP strains followed the curve only in NALT. The bacterial loads of S. Typhi RDAP strains were lower in NALT, lung, and Peyer's patches in mice born to immune mothers than in those born to naive mothers. In accordance with these results, RDAP vaccine strains induced high titers of IgG antibodies against PspA and against Salmonella lipopolysaccharides. Immunization of mothers with S. Typhi RDAP strains enhanced the level of vaginal mucosal IgA, gamma interferon (IFN-γ), and interleukin 4 (IL-4) and resulted in a higher level of protection against S. pneumoniae challenge.

  1. Oral delivery of the Sj23LHD-GST antigen by Salmonella typhimurium type III secretion system protects against Schistosoma japonicum infection in mice.

    Directory of Open Access Journals (Sweden)

    Guo Chen

    2011-09-01

    Full Text Available BACKGROUND: Schistosomiasis japonica is a zoonotic parasitic disease and oral vaccine delivery system would be benefit for prevention of this disease. Although attenuated salmonella has been used as an antigen expression vector for oral vaccine development, the membrane-bound vacuoles in which bacteria reside hinders the presentation of expressed heterologous antigens to the major histocompatibility complex (MHC molecules. The present work used an attenuated Salmonella typhimurium strain VNP20009 to secretory expression of Sj23LHDGST bivalent antigen from Schistosoma japonicum and tested the protective efficacy against S. japonicum infection in orally immunized mice. METHODOLOGY/PRINCIPAL FINDINGS: Promoters (nirB or pagC were used to express the antigen (Sj23LHDGST and the Salmonella type III or α-hemolysin secretion system was employed to secrete it. The immunoblotting analysis and fluorescent microscopy revealed that the antigen was effectively expressed and delivered to the cytosol of macrophages in vitro. Among recombinant vaccine strains, an engineered VNP20009 which expressed the antigen by nirB promoter and secreted it through type III secretion system (nirB-sopE(1-104-Sj23LHD-GST efficiently protected against S. japonicum infection in a mouse model. This strain elicited a predominantly IgG(2a antibody response and a markedly increase in the production of IL-12 and IFN-γ. The flow cytometric analysis demonstrated that this strain caused T cell activation as evidenced by significantly increased expression of CD44 and CD69. CONCLUSION/SIGNIFICANCE: Oral delivery of antigen by nirB-driven Salmonella typhimurium type III secretion system is a novel, safe, inexpensive, efficient and convenient approach for schistosome vaccine development.

  2. Excretion in feces and mucosal persistence of Salmonella ser. Typhimurium in pigs subclinically infected with Oesophagostomum spp

    DEFF Research Database (Denmark)

    Steenhard, N.R.; Jensen, Tim Kåre; Baggesen, Dorte Lau

    2002-01-01

    Objective-To determine interactions between Oesophagostomum spp and Salmonella ser. Typhimurium in pigs. Animals-30 healthy 5- to 6-week-old pigs. Procedure-Pigs were allotted to 3 groups (n = 10 pigs/group) and treated as follows: group A was given Oesophagostomum dentatum and 0 quadrispinulatum......; group B was given 0 dentatum, 0 quadrispinulatum, and S Typhimurium; and group C was given STyphimurium only. Pigs in groups A and B were trickle infected with Oesophagostomum spp 3 times weekly throughout the study. After 19 days, groups B and C were inoculated once with STyphimurium. One pig from each...... group was euthanatized on the day of Salmonella exposure and 2 and 4 days after Salmonella exposure. The remaining pigs were euthanatized on days 16 and 17 after Salmonella exposure. Results-Pigs with dual infections of nematodes and bacteria (group B) excreted significantly higher amounts of S...

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

    Science.gov (United States)

    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.

  4. Functional conservation among members of the Salmonella typhimurium InvA family of proteins.

    Science.gov (United States)

    Ginocchio, C C; Galán, J E

    1995-02-01

    InvA, which is essential for Salmonella spp. to enter cultured epithelial cells, is a member of a family of proteins involved in either flagellar biosynthesis or the secretion of virulence determinants by a number of plant and mammalian pathogens. The predicted overall secondary structures of these proteins show significant similarities and indicate a modular construction with a hydrophobic amino-terminal half, consisting of six to eight potential transmembrane domains, and a hydrophilic carboxy terminus which is predicted to reside in the cytoplasm. These proteins can be aligned over the entire length of their polypeptide sequences, with the highest degree of homology found in the amino terminus and clusters of conserved residues in the carboxy terminus. We examined the functional conservation among members of this protein family by assessing the ability of MxiA of Shigella flexneri and LcrD of Yersinia pseudotuberculosis to restore invasiveness to an invA mutant of Salmonella typhimurium. We found that MxiA was able to complement the entry defect of the invA mutant strain of S. typhimurium. In contrast, LcrD failed to complement the same strain. However, a plasmid carrying a gene encoding a chimeric protein consisting of the amino terminus of LcrD and the carboxy terminus of InvA complemented the defect of the Salmonella invA mutant. These results indicate that the secretory systems in which these proteins participate are functionally similar and that the Salmonella and Shigella systems are very closely related. These data also suggest that determinants of specificity may be located at the carboxy termini of these proteins.

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

    Directory of Open Access Journals (Sweden)

    Burkholder Kristin M

    2009-07-01

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

  6. Protein turnover analysis in Salmonella Typhimurium during infection by dynamic SILAC, Topograph, and quantitative proteomics.

    Science.gov (United States)

    Wang, Zhe; Han, Qiang-Qiang; Zhou, Mao-Tian; Chen, Xi; Guo, Lin

    2016-07-01

    Protein turnover affects protein abundance and phenotypes. Comprehensive investigation of protein turnover dynamics has the potential to provide substantial information about gene expression. Here we report a large-scale protein turnover study in Salmonella Typhimurium during infection by quantitative proteomics. Murine macrophage-like RAW 264.7 cells were infected with SILAC labeled Salmonella. Bacterial cells were extracted after 0, 30, 60, 120, and 240 min. Mass spectrometry analyses yielded information about Salmonella protein turnover dynamics and a software program named Topograph was used for the calculation of protein half lives. The half lives of 311 proteins from intracellular Salmonella were obtained. For bacteria cultured in control medium (DMEM), the half lives for 870 proteins were obtained. The calculated median of protein half lives was 69.13 and 99.30 min for the infection group and the DMEM group, respectively, indicating an elevated protein turnover at the initial stage of infection. Gene ontology analyses revealed that a number of protein functional groups were significantly regulated by infection, including proteins involved in ribosome, periplasmic space, cellular amino acid metabolic process, ion binding, and catalytic activity. The half lives of proteins involved in purine metabolism pathway were found to be significantly shortened during infection.

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

    Science.gov (United States)

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

    2009-01-01

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

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

    Science.gov (United States)

    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.

  9. In-Vitro Adhesion and Invasion Properties of Salmonella Typhimurium Competing with Bacteriophage in Epithelial Cells and Chicken Macrophages

    Directory of Open Access Journals (Sweden)

    HY Lee

    2015-12-01

    Full Text Available ABSTRACT This study was designed to assess the role of bacteriophage P22 in the adhesion, invasion, intracellular survival of, and cellular immune response to Salmonella Typhimurium in intestinal epithelial INT-407 and chicken macrophage-like HD11 cells. The ability of S. Typhimurium to adhere, invade, and survive to INT-407 and HD11cells was evaluated under Salmonella infection alone (control, phage treatment followed by Salmonella infection (PS, Salmonella infection followed by phage treatment (SP, and a combination treatment with Salmonella and phage (S+P. The number of S. Typhimurium associated on INT-407 cells was reduced from 4.2 to 2.7 log cfu/cm2 by phage treatment (SP. The number of intracellular S. Typhimurium within INT-407 cells was significantly reduced to below the detection limit (0.7 log cfu/cm2 compared with the control (3.4 log cfu/cm2. S. Typhimurium remained inside HD11 cells at 49% and 17% levels in the absence and presence of phages, respectively, at 24 h post-infection (hpi. The expression levels of IFN-g, IL-10, IL-1b, IL-6, IL-8, iNOS, and IL-12 increased in HD11 cells regardless the absence and presence of phages, while those of IL-16, TLR2-1, TLR3, and TLR7 were decreased at 0 and 24 hpi. This study sheds new light on our understanding of the role of phages in Salmonella adhesion, invasion, survival, and cellular immune responses.

  10. Biofilm formation ability of Salmonella enterica serovar Typhimurium acrAB mutants.

    Science.gov (United States)

    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.

  11. Antimicrobial Effectiveness of Biobased Film Against Escherichia coli 0157:H7, Listeria monocytogenes and Salmonella typhimurium

    Directory of Open Access Journals (Sweden)

    Pornpun Theinsathid

    2011-08-01

    Full Text Available Antimicrobial packaging, an active packaging concept, can be considered challenging technology that could have a significant impact on food safety of meat and meat products. The feasibility of polylactic acid (PLA-based film was evaluated for its application as a material for antimicrobial film. A bio-based commercial polylactic acid (PLA product, Ecovio®, was used as an environmentally friendly polymer matrix. The PLA based film was incorporated with lactic acid or sodium lactate by extrusion film-blowing process. The antimicrobial activity of films against Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica Serovar Typhimurium (S. Typhimurium were evaluated. Antimicrobial film incorporated with lactic acid packaging film was found to be highly effective in inhibiting L. monocytogenes. In contrast, no inhibitory activity was observed against E. coli O157:H7 and S. Typhimurium. This is consistent with Minimum Inhibitory Concentration (MIC studies which indicated that undissociated lactic acid was more efficient in inhibiting L. monocytogenes than enterobacteria. This preliminary study shows the potential use of bio-based film as one hurdle technology in combination with good manufacturing practices and adequate storage temperatures. The use of antimicrobial packaging may contribute to improve the safety in minimally processed foods. Further work is required to improve the mechanical properties of the material in order to meet industry requirements.

  12. The type VI secretion system gene cluster of Salmonella typhimurium: required for full virulence in mice.

    Science.gov (United States)

    Liu, Ji; Guo, Ji-Tao; Li, Yong-Guo; Johnston, Randal N; Liu, Gui-Rong; Liu, Shu-Lin

    2013-07-01

    Type VI secretion system (T6SS) has increasingly been believed to participate in the infection process for many bacterial pathogens, but its role in the virulence of Salmonella typhimurium remains unclear. To look into this, we deleted the T6SS cluster from the genome of S. typhimurium 14028s and analyzed the phenotype of the resulting T6SS knockout mutant (T6SSKO mutant) in vitro and in vivo. We found that the T6SSKO mutant exhibited reduced capability in colonizing the spleen and liver in an in vivo colonization competition model in BALB/c mice infected by the oral route. Additionally, infection via intraperitoneal administration also showed that the T6SSKO mutant was less capable of colonizing the mouse spleen and liver than the wild-type strain. We did not detect significant differences between the T6SSKO and wild-type strains in epithelial cell invasion tests. However, in the macrophage RAW264.7 cell line, the T6SSKO mutant survived and proliferated significantly more poorly than the wild-type strain. These findings indicate that T6SS gene cluster is required for full virulence of S. typhimurium 14028s in BALB/c mice, possibly due to its roles in bacterial survival and proliferation in macrophages.

  13. Prophylaxis of tumor through oral administration of IL-12 GM-CSF gene carried by live attenuated salmonella

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A live attenuated AraA- autotrophic mutant of Salmonella typhimurium (SL3261) was used as carrier for eukaryotic expression vectors EGFPN1, pCMVmIL-12, pCMVhIL-12, pCMVmGM-CSF and pCMVhGM-CSF and was administered orally to BALB/c and C57BL/6 mice. After 6 weeks, these mice were challenged with 4T1 and Lewis tumor cells respectively. GFP expression and gene integrati-on could be detected in mice's livers, spleens, intestines, kidneys and tumors. The serum level of cytokines increased significantly in treated mice, so did the ratio of , which resulted in the tumor regression and prolongation of the survival time of those mice. These researches laid an experimental foundation for the tumor gene therapy using live attenuated salmonella.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Saiful M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shi, Liang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Yoon, Hyunjin [Dartmouth College, Hanover, NH (United States); Ansong, Charles [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rommereim, Leah M. [Dartmouth College, Hanover, NH (United States); Norbeck, Angela D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Auberry, Kenneth J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Moore, R. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Adkins, Joshua N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Heffron, Fred [Oregon Health and Science Univ., Portland, OR (United States); Smith, Richard D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    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. .

  15. Isolation and plasmid characterization of carbapenemase (IMP-4) producing Salmonella enterica Typhimurium from cats

    Science.gov (United States)

    Abraham, Sam; O’Dea, Mark; Trott, Darren J.; Abraham, Rebecca J.; Hughes, David; Pang, Stanley; McKew, Genevieve; Cheong, Elaine Y. L.; Merlino, John; Saputra, Sugiyono; Malik, Richard; Gottlieb, Thomas

    2016-01-01

    Carbapenem-resistant Enterobacteriaceae (CRE) are a pressing public health issue due to limited therapeutic options to treat such infections. CREs have been predominantly isolated from humans and environmental samples and they are rarely reported among companion animals. In this study we report on the isolation and plasmid characterization of carbapenemase (IMP-4) producing Salmonella enterica Typhimurium from a companion animal. Carbapenemase-producing S. enterica Typhimurium carrying blaIMP-4 was identified from a systemically unwell (index) cat and three additional cats at an animal shelter. All isolates were identical and belonged to ST19. Genome sequencing revealed the acquisition of a multidrug-resistant IncHI2 plasmid (pIMP4-SEM1) that encoded resistance to nine antimicrobial classes including carbapenems and carried the blaIMP-4-qacG-aacA4-catB3 cassette array. The plasmid also encoded resistance to arsenic (MIC-150 mM). Comparative analysis revealed that the plasmid pIMP4-SEM1 showed greatest similarity to two blaIMP-8 carrying IncHI2 plasmids from Enterobacter spp. isolated from humans in China. This is the first report of CRE carrying a blaIMP-4 gene causing a clinical infection in a companion animal, with presumed nosocomial spread. This study illustrates the broader community risk entailed in escalating CRE transmission within a zoonotic species such as Salmonella, and in a cycle that encompasses humans, animals and the environment. PMID:27767038

  16. Branched-chain amino acid supplementation promotes aerobic growth of Salmonella Typhimurium under nitrosative stress conditions.

    Science.gov (United States)

    Park, Yoon Mee; Lee, Hwa Jeong; Jeong, Jae-Ho; Kook, Joong-Ki; Choy, Hyon E; Hahn, Tae-Wook; Bang, Iel Soo

    2015-12-01

    Nitric oxide (NO) inactivates iron-sulfur enzymes in bacterial amino acid biosynthetic pathways, causing amino acid auxotrophy. We demonstrate that exogenous supplementation with branched-chain amino acids (BCAA) can restore the NO resistance of hmp mutant Salmonella Typhimurium lacking principal NO-metabolizing enzyme flavohemoglobin, and of mutants further lacking iron-sulfur enzymes dihydroxy-acid dehydratase (IlvD) and isopropylmalate isomerase (LeuCD) that are essential for BCAA biosynthesis, in an oxygen-dependent manner. BCAA supplementation did not affect the NO consumption rate of S. Typhimurium, suggesting the BCAA-promoted NO resistance independent of NO metabolism. BCAA supplementation also induced intracellular survival of ilvD and leuCD mutants at wild-type levels inside RAW 264.7 macrophages that produce constant amounts of NO regardless of varied supplemental BCAA concentrations. Our results suggest that the NO-induced BCAA auxotrophy of Salmonella, due to inactivation of iron-sulfur enzymes for BCAA biosynthesis, could be rescued by bacterial taking up exogenous BCAA available in oxic environments.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2016-08-22

    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.

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

    Directory of Open Access Journals (Sweden)

    Ou Yun

    2016-08-01

    Full Text Available 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.

  20. Protective Effect of Moderate Exercise for BALB/c Mice with Salmonella Typhimurium Infection.

    Science.gov (United States)

    Campos-Rodríguez, R; Godínez-Victoria, M; Arciniega-Martínez, I M; Reséndiz-Albor, A A; Reyna-Garfias, H; Cruz-Hernández, T R; Drago-Serrano, M E

    2016-01-01

    Moderate exercise enhances resistance to pathogen-associated infections. However, its influence on intestinal IgA levels and resistance to Salmonella typhimurium in mice has not been reported. The aim of this study was to assess the impact of moderate exercise on bacterial resistance and the intestinal-IgA response in a murine typhoid model. Sedentary and exercised (under a protocol of moderate swimming) BALB/c mice were orally infected with Salmonella typhimurium and sacrificed on days 7 or 14 post-infection (n=5 per group). Compared with infected sedentary mice, infected exercised animals had i) lower intestinal and systemic bacterial loads; ii) higher total and specific intestinal-IgA levels, iii) a higher percentage of IgA plasma cells in lamina propria; iv) a higher level on day 7 and lower level on day 14 of intestinal α- and J-chain mRNA and plasma corticosterone, v) unchanged mRNA expression of intestinal pIgR, and vi) a higher mRNA expression of liver pIgR, α-chain and J-chain on day 7. Hence, it is likely that an increase in corticosterone levels (stress response) induced by moderate exercise increased intestinal IgA levels by enabling greater liver expression of pIgR mRNA, leading to a rise in IgA transcytosis from the liver to intestine. The overall effect of these changes is an enhanced resistance to infection.

  1. Efficacy of Some Commercial Chemical Disinfectants on Salmonella enterica Serovar Typhimurium

    Directory of Open Access Journals (Sweden)

    Essam S. Soliman

    2009-01-01

    Full Text Available Problem statement: Poultry industry is intensive and consistently applies an all-in, all-out system with the aim of minimizing infection pressure and targeting specific pathogens like Salmonella which remains one of the leading causes of food-borne illness, many questions regarding the introduction and persistence in animal production still remain. Therefore disinfection during production break is a routine part of the biosecurity programs of poultry houses. The correct usage of disinfectants is an important key of a successful biosecurity program in poultry farms and in-turn the role of the scientist was to evaluate the efficacy of these disinfection programs. Approach: In this study five commercial disinfectants [Green work (green non anionic surfactant, Sanidate RTU (hydrogen peroxide compound, Hi-yeild®consan 20® (phenolic compound, Tektrol® (quaternary ammonium compound and Kreso®D (phenolic compound] were evaluated against Salmonella typhimurium in two different experimental conditions. In Experiment I, S. typhimurium was inoculated into fresh poultry litter (aluminum trays L: 30 cm x W: 25 cm x D: 6 cm filled with wood shavings by inoculums size of ~107 CFU mL-1 and then mixed with 100 g of fresh poultry droppings. Sample sizes of 3 g were obtained daily for the bacterial counts. Green work achieved100% killing of S. typhimurium by day 7 (p≤0.0001; Sanidate RTU achieved100% killing by day 6 (p≤0.001; Hi-yield® Consan®, Tektrol® and Kreso® D achieved100% killing by day 5 (p≤0.001. Disinfectants were also compared to each other in their efficacy each day. At day 1, Green work was inferior to all other disinfectants at (p≤0.05. On day 2, Kreso® D was significantly superior to Tektrol®, Hi-yield® Consan®, Sanidate RTU and Green work at p≤0.01, p≤0.01, p≤0.01, p≤0.005; respectively. At day 4 Kreso® D was significantly superior to Hi-yield® Consan® at p≤0.01, Tektrol® was also significantly superior to Green

  2. Contribution of oqxAB and aac(6’Ib-cr to fluoroquinolone resistance in Salmonella Typhimurium

    Directory of Open Access Journals (Sweden)

    Marcus Ho-yin eWong

    2014-10-01

    Full Text Available Emergence of multidrug-resistant S. Typhimurium strains, especially the ACSSuT and nalidixic acid R types, has significantly compromised the effectiveness of current strategies to control Salmonella infections, resulting in increased morbidity and mortality. Clinical S. Typhimurium isolates recovered in Hong Kong during the period of 2005-2011 were increasingly resistant to ciprofloxacin and antibiotics of the ACSSuT group. Our data revealed that oqxAB and aac(6’Ib-cr were encoded on plasmids of various sizes and the presence of these two elements together with a single gyrA mutation in S. Typhimurium were sufficient to mediate resistance to ciprofloxacin. Acquisition of the oqxAB and aac(6'Ib-cr encoding plasmids by S. Typhimurium caused a 4-fold increase in CIP MIC. Furthermore, the presence of oqxAB and aac(6'Ib-cr in Salmonella dramatically increased the mutation prevention concentration (MPC of ciprofloxacin which may due to mutational changes in the drug target genes. In conclusion, possession of oqxAB and aac(6’Ib-cr encoding plasmid facilitate the selection of ciprofloxacin resistant S. Typhimurium, thereby causing a remarkable increase of ciprofloxacin resistance among clinical Salmonella strains in Hong Kong.

  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.

    Science.gov (United States)

    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. Life-Threatening Infantile Diarrhea from Fluoroquinolone-Resistant Salmonella enteric Typhimurium with Mutations in Both gyrA and parC

    OpenAIRE

    Nakaya, Hideo; Yasuhara, Akihiro; Yoshimura, Ken; Oshihoi, Yukio; Izumiya, Hidemasa; Watanabe, Haruo

    2003-01-01

    Salmonella Typhimurium DT12, isolated from a 35-day-old infant with diarrhea, was highly resistant to ampicillin, tetracycline, chloramphenicol, streptomycin, gentamycin, sulfamethoxazole/trimethoprim, nalidixic acid, and fluoroquinolones. The patient responded to antibiotic therapy with fosfomycin. Multidrug-resistance may become prevalent in Salmonella infections in Japan, as shown in this first case of a patient infected with fluoroquinolone-resistant Salmonella.

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

    Science.gov (United States)

    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.

  6. Genotoxicity investigation of ELF-magnetic fields in Salmonella typhimurium with the sensitive SOS-based VITOTOX test

    NARCIS (Netherlands)

    Verschaeve, Luc; Anthonissen, Roel; Grudniewska, Magda; Wudarski, Jakub; Gevaert, Lieven; Maes, Annemarie

    2011-01-01

    We performed a genotoxicity investigation of extremely low-frequency (ELF) magnetic fields (MFs, 50 Hz, 100 and 500 µT, 1 and 2 h exposure) alone and in combination with known chemical mutagens using the VITOTOX test. This test is a very sensitive reporter assay of Salmonella typhimurium bacteria ba

  7. Experimental Salmonella typhimurium infections in rats. II. Active and passive immunization as protection against a lethal bacterial dose

    DEFF Research Database (Denmark)

    Hougen, H P; Jensen, E T; Klausen, B

    1990-01-01

    Immunization against a lethal dose of Salmonella typhimurium was studied in athymic and thymus-bearing LEW rats. Active immunization was performed with formalin-killed whole cell vaccine or sublethal infection prior to the lethal infection. After vaccination with killed bacteria the euthymic anim...

  8. BEHAVIOR OF ESCHERICHIA COLI O157:H7, LISTERIA MONOCYTOGENES, AND SALMONELLA TYPHIMURIUM IN TEEWURST, A RAW SPREADABLE SAUSAGE

    Science.gov (United States)

    The fate of Listeria monocytogenes, Salmonella Typhimurium, or Escherichia coli O157:H7 were separately monitored both in and on teewurst, a traditional raw and spreadable sausage of Germanic origin. Multi-strain cocktails of each pathogen (ca. 5.0 log CFU/g) were used to separately inoculate teewur...

  9. Survival of Salmonella Typhimurium on soybean sprouts after treatment with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

    Science.gov (United States)

    Control of Salmonella Typhimurium on sprouts and minimally processed produce is crucial for food and consumer safety. The aim of this research was to assess natural microflora populations on soybean and evaluate the effects of gaseous chlorine dioxide (ClO2) and biocontrol Pseudomonas on the surviva...

  10. Ecology and modelling of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in cattle manure and soil

    NARCIS (Netherlands)

    Semenov, A.V.

    2008-01-01

    The number of food poisoning cases caused by enteropathogens has increased in recent years. A significant part of the outbreaks associated with the consumption of raw vegetables has been attributed to Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium. Bovine manure

  11. Phage types of Salmonella enterica ssp. enterica serovar Typhimurium isolated from production animals and humans in Denmark

    DEFF Research Database (Denmark)

    Baggesen, Dorte Lau; Wegener, Henrik Caspar

    1994-01-01

    S. Typhimurium is one of the 2 most common salmonella serotypes causing human salmonellosis in Denmark. In order to illustrate the significance of different production animals as a source of infection, 1461 isolates were characterized by phage typing. The isolates originated from human patients...

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

    Science.gov (United States)

    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...

  13. Functional and crystallographic characterization of Salmonella typhimurium Cu,Zn superoxide dismutase coded by the sodCI virulence gene

    NARCIS (Netherlands)

    Pesce, A; Battistoni, A; Stroppolo, ME; Polizio, F; Nardini, M; Kroll, JS; Langford, PR; O'Neill, P; Sette, M; Desideri, A; Bolognesi, M

    2000-01-01

    The functional and three-dimensional structural features of Cu,Zn superoxide dismutase coded by the Salmonella typhimurium sodCI gene, have been characterized. Measurements of the catalytic rate indicate that this enzyme is the most efficient superoxide dismutase analyzed so far, a feature that may

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

    Science.gov (United States)

    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...

  15. Characterization of the yehUT two-component regulatory system of Salmonella enterica Serovar Typhi and Typhimurium.

    Science.gov (United States)

    Wong, Vanessa K; Pickard, Derek J; Barquist, Lars; Sivaraman, Karthikeyan; Page, Andrew J; Hart, Peter J; Arends, Mark J; Holt, Kathryn E; Kane, Leanne; Mottram, Lynda F; Ellison, Louise; Bautista, Ruben; McGee, Chris J; Kay, Sally J; Wileman, Thomas M; Kenney, Linda J; MacLennan, Calman A; Kingsley, Robert A; Dougan, Gordon

    2013-01-01

    Proteins exhibiting hyper-variable sequences within a bacterial pathogen may be associated with host adaptation. Several lineages of the monophyletic pathogen Salmonella enterica serovar Typhi (S. Typhi) have accumulated non-synonymous mutations in the putative two-component regulatory system yehUT. Consequently we evaluated the function of yehUT in S. Typhi BRD948 and S. Typhimurium ST4/74. Transcriptome analysis identified the cstA gene, encoding a carbon starvation protein as the predominantly yehUT regulated gene in both these serovars. Deletion of yehUT had no detectable effect on the ability of these mutant Salmonella to invade cultured epithelial cells (S. Typhi and S. Typhimurium) or induce colitis in a murine model (S. Typhimurium only). Growth, metabolic and antimicrobial susceptibility tests identified no obvious influences of yehUT on these phenotypes.

  16. Growth suppression of antibiotic-resistant Salmonella typhimurium DT104 by a non-DT104 strain in vitro

    Directory of Open Access Journals (Sweden)

    Ngwai YB

    2006-12-01

    Full Text Available Growth suppression of antibiotic-resistant Salmonella typhimurium DT104 by a non-DT104 strain was investigated in vitro. Chromosomal mutants of eight antibiotic-resistant DT104 strains were generated by sub-culturing on desoxycholate hydrogen sulfide lactose agar containing 25 µg/ml of nalidixic acid. Low counts of each of these mutants (designated as “minority cultures” were inoculated into 24-h cultures of a non-DT104 S. typhimurium strain (designated as “majority culture” to test the ability of the majority culture to suppress the multiplication of the minority culture. Multiplication of small numbers of the antibiotic-resistant DT104 strains was significantly (P < 0.05 prevented when the DT104s were added to 24-h brain heart infusion cultures of the non-DT104 strain. This observation has practical implications for the control of the menacing antibiotic-resistant Salmonella typhimurium DT104.

  17. Effects of gamma irradiation for inactivating Salmonella Typhimurium in peanut butter product during storage.

    Science.gov (United States)

    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 (pbutter 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.

  18. Ribonucleotide reductases of Salmonella typhimurium: transcriptional regulation and differential role in pathogenesis.

    Directory of Open Access Journals (Sweden)

    Anaïs Panosa

    Full Text Available Ribonucleotide reductases (RNRs are essential enzymes that carry out the de novo synthesis of deoxyribonucleotides by reducing ribonucleotides. There are three different classes of RNRs (I, II and III, all having different oxygen dependency and biochemical characteristics. Salmonella enterica serovar Typhimurium (S. Typhimurium harbors class Ia, class Ib and class III RNRs in its genome. We have studied the transcriptional regulation of these three RNR classes in S. Typhimurium as well as their differential function during infection of macrophage and epithelial cells. Deletion of both NrdR and Fur, two main transcriptional regulators, indicates that Fur specifically represses the class Ib enzyme and that NrdR acts as a global repressor of all three classes. A Fur recognition sequence within the nrdHIEF promoter has also been described and confirmed by electrophoretic mobility shift assays (EMSA. In order to elucidate the role of each RNR class during infection, S. Typhimurium single and double RNR mutants (as well as Fur and NrdR mutants were used in infection assays with macrophage and epithelial cell lines. Our results indicate class Ia to be mainly responsible for deoxyribonucleotide production during invasion and proliferation inside macrophages and epithelial cells. Neither class Ib nor class III seem to be essential for growth under these conditions. However, class Ib is able to maintain certain growth in an nrdAB mutant during the first hours of macrophage infection. Our results suggest that, during the early stages of macrophage infection, class Ib may contribute to deoxyribonucleotide synthesis by means of both an NrdR and a Fur-dependent derepression of nrdHIEF due to hydrogen peroxide production and DNA damage associated with the oxidative burst, thus helping to overcome the host defenses.

  19. Phage-based magnetoelastic biosensor for the detection of Salmonella typhimurium

    Science.gov (United States)

    Li, Suiqiong; Lakshmanan, Ramji S.; Guntupalli, Rajesh; Huang, Shichu; Cheng, Z.-Y.; Petrenko, Valery A.; Barbaree, James M.; Vodyanoy, Vitaly; Chin, Bryan A.

    2009-05-01

    In this paper, we report a wireless magnetoelastic (ME) biosensor with phage as the bio-recognition probe for real time detection of Salmonella typhimurium. The ME biosensor was constructed by immobilizing filamentous phage that specifically binds with S. typhimurium onto the surface of a strip-shaped ME particle. The ME sensor oscillates with a characteristic resonance frequency when subjected to a time varying magnetic field. Binding between the phage and antigen (bacteria) causes a shift in the sensor's resonance frequency. Sensors with different dimensions were exposed to various known concentrations of S. typhimurium ranging from 5 x101 to 5 x 108 cfu/ml. The detection limit of the ME sensors was found to improve as the size of the sensor became smaller. The detection limit was found to improve from 161 Hz/decade (2mm length sensors) to 1150 Hz/decade (500 μm length sensors). The stability of the ME biosensor was investigated by storing the sensor at different temperatures (25, 45, and 65 °C), and then evaluating the binding activity of the stored biosensor after exposure to S. typhimurium solution (5 x 108 cfu/ml). The results showed that the phage-coated biosensor is robust. Even after storage in excess of 60 days at 65 °C, the phage-coated sensors have a greater binding affinity than the best antibody coated sensors stored for 1 day at 45 °C. The antibody coated sensors showed near zero binding affinity after 3 days of storage at 65 °C.

  20. Construction and Identification of Attenuated Salmonella typhimurium Harbouring S/N Double Fusion Genes of Porcine Transmissible Gastroenteritis Virus%携带猪传染性胃肠炎病毒S/N融合双基因的减毒沙门氏菌的构建与鉴定

    Institute of Scientific and Technical Information of China (English)

    黄小波; 李春松; 杨恒; 曹三杰; 文心田; 廖晓丹; 张鑫淼

    2012-01-01

    旨在构建携带猪传染性胃肠炎病毒(TGEV)S/N融合双基因的减毒沙门氏菌,并鉴定该疫苗菌株的生物学特性,为开展TGEV口服免疫研究奠定材料基础.采用PCR方法从克隆质粒19T-S和19T-N中分别扩增了TGEV的S基因(含主要抗原位点,2.1kb)和N基因(1.2 kb),将S基因和N基因插入pVAX1载体,构建携带S/N融合双基因的真核表达质粒pVAX-S/N.将pVAX-S/N电转化减毒沙门氏菌SL7207,筛选获得重组菌株SL7207 (pVAX-S/N),并对重组菌株SL7207 (pVAX-S/N)的体外稳定性、目的基因在体内的转录、口服接种小鼠的安全性及在体内稳定性等特性进行了鉴定.结果表明,真核质粒pVAX-S/N构建成功,该质粒转染COS7中能表达2个目的蛋白,重组菌SL7207 (pVAX-S/N)在Kan+抗性下体外培养稳定性好,口服接种小鼠3d可从回肠组织检测到目的基因的转录,以0.5×10 9、1×10 9和2×109 CFU口服对小鼠均具有安全性,重组菌在接种小鼠的肝、脾于4周左右逐渐被机体清除.结果表明成功构建TGEV S/N双基因疫苗SL7207 (pVAX-S/N),该疫苗具有良好的稳定性与安全性等特点,为开展TGEV口服免疫研究奠定了基础.%To provide a new vaccine for oral immunization of transmissible gastroenteritis virus (TGEV) , attenuated Salmonella typhimurium harbouring S/N double fusion genes of (TGEV) was constructed and identified. The S gene fragment (2. 1 kb) and the N gene fragment (1. 2 kb) were respectively amplified from the recombinant plasmid 19T-S and 19T-N of TGEV by RT-PCR, and then the two gene fragments were successively inserted into the eukaryotic expression vector pVAXl to construction the recombinant eukaryotic expression plasmid pVAX-S/N that expressing the S-N double fusion gene. The plasmid pVAX-S/N was identified by PCR and restric-tive digestion, and then the pVAX-S/N was transfected into COS7 cells through liposome trans-fection to identify the expressions of the two target genes hy indirect

  1. Factores Gre de Salmonella enterica serovar Typhimurium, su papel en el control de la filosofía y patogenicidad

    OpenAIRE

    Gaviria Cantín, Tania Cristina

    2016-01-01

    [spa] El género Salmonella, está compuesto de bacterias Gram-negativas, no esporuladas, en forma de bacilo. Salmonella tiene importante relevancia a nivel de salud pública ya que es uno de los principales patógenos entéricos tanto en países desarrollados como en vías de desarrollo. En los casos de gastroenteritis notificados en España, Salmonella se posiciona en segundo lugar, después de Campylobacter. En este trabajo se utilizó como organismo modelo de estudio S. enterica serovar Typhimurium...

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

    Science.gov (United States)

    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.

  3. The muc+ gene of plasmid pKM101 prevents respiration shutoff in far ultraviolet-irradiated Salmonella typhimurium.

    Science.gov (United States)

    Swenson, P A

    1981-01-01

    The plasmid PKM101 is known to protect Escherichia coli and Salmonella typhimurium against killing by far UV irradiation and to enhance UV-induced mutagenesis. The muc+ gene of the plasmid is responsible for both of these effects. This paper shows that respiration of S. typhimurium shuts off about an hour after UV irradiation and that pKM101 prevents the shutoff. Plasmids which contained Tn5 translocatable elements, either in (and having produced a muc mutation) or flanking the muc+ gene, have been introduced into S. typhimurium. The muc mutant plasmid, which does not protect its host against UV killing and does not enhance UV induced mutagenesis, also does not protect against UV induced respiration shutoff. Likewise, plasmids in which the Tn5 translocatable elements flank the muc+ gene protect against shutoff of respiration. Thus the muc+ gene of pKM101 is responsible for protection against UV induced shutoff of respiration in S. typhimurium.

  4. Construction of the recombinant attenuated Salmonella typhimurium under the control of the in vivo inducible nirB promoter%NirB启动子调控下鼠沙门氏菌体内诱导型表达载体的构建

    Institute of Scientific and Technical Information of China (English)

    郭恒; 刘明远; 王光明; 王学林; 李慧萍; 刘学; 张凌怡; 唐艺芝; 高鹤; 杨秀丽; 徐德启

    2011-01-01

    目的 构建遗传稳定性良好的沙门氏菌体内诱导型表达载体.方法 以克隆载体pGB2为基础,将沙门氏菌厌氧启动子PnirB和EGFP基因串联,并在其多克隆位点 MCS 下游引入 rrnbT1T2 转录终止序列,构建沙门氏菌低拷贝体内诱导型表达载体 pGnirB-EGFP-rrnb,电转化入鼠伤寒沙门氏菌phoP/phoQ株,对质粒的稳定性及蛋白表达情况进行检测.结果 含有低拷贝重组质粒的沙门氏菌在缺失抗生素选择压力下盲传100代后质粒稳定性高于95%,在厌氧静置72 h培养后激光共聚焦显微镜下可观察到明显绿色荧光.结论 高度稳定的沙门氏菌体内诱导型表达载体构建成功,为研制以鼠伤寒沙门氏菌为活载体的新型口服疫苗奠定了基础.%Objective Construction of a stable expression vector under the controlof the in vivo inducible nirB promoter in the salm onella typhim urium (S . typhim urium ) .Methods Anaerobic promoter P nir B of salm onella and EGFP were connected into cloning vector pGB2 ,rmbT1T2 transcription termination sequence was inserted into the downstrean of multiply clone sites(M CS) .This plasmid was introduced into S .typhimurium strain phoP/phoQ .The stability of pGB2-based vaccine constructs was determined .The expression of report gene EGFP was detected. Results Salmonella contained pGB2-based plasm id was cultivated for 100 generations without an-tibiotic selection ,the stability of plasm id was up to 95% .Strong green fluorescent can be observed after stationary cultivation for 72 hours under laser scanning confocal microscope. Conclusion The low-copy-number internal-induced eukaryotic expression vector f pG nirB-EGFP-rmb was constructed successfully and stably expressed in salm onella under the control of the in vivo inducible PnirB promoter.It laid a foundation of further study on a new type pre-exposure oral vaccine by using attenuated salm onella as vector.

  5. Experimental annotation of post-translational features and translated coding regions in the pathogen Salmonella Typhimurium

    Directory of Open Access Journals (Sweden)

    Smith Richard D

    2011-08-01

    Full Text Available Abstract Background Complete and accurate genome annotation is crucial for comprehensive and systematic studies of biological systems. 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. Results We experimentally annotated the bacterial pathogen Salmonella Typhimurium 14028, using "shotgun" proteomics to accurately uncover the translational landscape and post-translational features. The data provide protein-level experimental validation for approximately half of the predicted protein-coding genes in Salmonella and suggest revisions to several genes that appear to have incorrectly assigned translational start sites, including a potential novel alternate start codon. Additionally, we uncovered 12 non-annotated genes missed by gene prediction programs, as well as evidence suggesting a role for one of these novel ORFs in Salmonella pathogenesis. We also characterized post-translational features in the Salmonella genome, including chemical modifications and proteolytic cleavages. We find that bacteria have a much larger and more complex repertoire of chemical modifications than previously thought including several novel modifications. Our in vivo proteolysis data identified more than 130 signal peptide and N-terminal methionine cleavage events critical for protein function. Conclusion This work highlights several ways in which application of proteomics data can improve the quality of genome annotations to facilitate novel biological insights and provides a comprehensive proteome map of Salmonella as a resource for systems analysis.

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

    Science.gov (United States)

    Arsenault, Ryan J; Napper, Scott; Kogut, Michael H

    2013-05-17

    Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) infection of chickens that are more than a few days old results in asymptomatic cecal colonization with persistent shedding of bacteria. We hypothesized that while the bacterium colonizes and persists locally in the cecum it has systemic effects, including changes to metabolic pathways of skeletal muscle, influencing the physiology of the avian host. Using species-specific peptide arrays to perform kinome analysis on metabolic signaling pathways in skeletal muscle of Salmonella Typhimurium infected chickens, we have observed key metabolic changes that affected fatty acid and glucose metabolism through the 5'-adenosine monophosphate-activated protein kinase (AMPK) and the insulin/mammalian target of rapamycin (mTOR) signaling pathway. Over a three week time course of infection, we observed changes in the phosphorylation state of the AMPK protein, and proteins up and down the pathway. In addition, changes to a large subset of the protein intermediates of the insulin/mTOR pathway in the skeletal muscle were altered by infection. These changes occur in pathways with direct effects on fatty acid and glucose metabolism. This is the first report of significant cellular metabolic changes occurring systemically in chicken due to a Salmonella infection. These results have implications not only for animal production and health but also for the understanding of how Salmonella infection in the intestine can have widespread, systemic effects on the metabolism of chickens without disease-like symptoms.

  7. Amplification of an invA gene sequence of Salmonella typhimurium by polymerase chain reaction as a specific method of detection of Salmonella.

    Science.gov (United States)

    Rahn, K; De Grandis, S A; Clarke, R C; McEwen, S A; Galán, J E; Ginocchio, C; Curtiss, R; Gyles, C L

    1992-08-01

    Amplification of nucleotide sequences within the invA gene of Salmonella typhimurium was evaluated as a means of detecting Salmonella. A collection of 630 strains of Salmonella comprising over 100 serovars, including the 20 most prevalent serovars isolated from animals and humans in Canada, was examined. Controls consisted of 142 non-Salmonella strains comprising 21 genera of bacteria. Cultures were screened by inoculating a single colony of bacteria directly into a polymerase chain reaction (PCR) mixture which contained a pair of primers specific for the invA gene. The specific PCR product was a 284 bp DNA fragment which was visualized in 2% agarose gels. With the exception of two S. litchfield and two S. senftenberg strains, all Salmonella strains were detected. In contrast, none of the non-Salmonella strains yielded the specific amplification product. Non-specific amplification of a few non-Salmonella strains resulted in a product that was distinctly different in size from the specific 284 bp product. Specificity of amplification was further confirmed by demonstration of hybridization of a 32P-labelled invA gene fragment only to the specific 284 bp product. The detection of 99.4% of Salmonella strains tested and the failure to specifically amplify DNA from non-Salmonella strains confirm that the invA gene contains sequences unique to Salmonella and demonstrate that this gene is a suitable PCR target, with potential diagnostic applications.

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

    Science.gov (United States)

    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.

  9. An oral recombinant Salmonella enterica serovar Typhimurium mutant elicits systemic antigen-specific CD8+ T cell cytokine responses in mice

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    Chin'ombe Nyasha

    2009-04-01

    Full Text Available Abstract Background The induction of antigen-specific CD8+ T cell cytokine responses against an attenuated, oral recombinant Salmonella enterica serovar Typhimurium vaccine expressing a green fluorescent protein (GFP model antigen was investigated. A GFP expression plasmid was constructed in which the gfp gene was fused in-frame with the 5' domain of the Escherichia coli β-galactosidase α-gene fragment with expression under the lac promoter. Groups of mice were orally immunized three times with the bacteria and systemic CD8+ T cell cytokine responses were evaluated. Results High level of the GFP model antigen was expressed by the recombinant Salmonella vaccine vector. Systemic GFP-specific CD8+ T cell cytokine (IFN-γ and IL-4 immune responses were detected after mice were orally vaccinated with the bacteria. It was shown that 226 net IFN-γ and 132 net IL-4 GFP-specific SFUs/10e6 splenocytes were formed in an ELISPOT assay. The level of IFN-γ produced by GFP peptide-stimulated cells was 65.2-fold above background (p Conclusion These results suggested that a high expressing recombinant Salmonella vaccine given orally to mice would elicit antigen-specific CD8+ T cell responses in the spleen. Salmonella bacteria may, therefore, be used as potential mucosal vaccine vectors.

  10. Assessment of root uptake and systemic vine-transport of Salmonella enterica sv. Typhimurium by melon (Cucumis melo) during field production.

    Science.gov (United States)

    Lopez-Velasco, Gabriela; Sbodio, Adrian; Tomás-Callejas, Alejandro; Wei, Polly; Tan, Kin Hup; Suslow, Trevor V

    2012-08-01

    Among melons, cantaloupes are most frequently implicated in outbreaks and surveillance-based recalls due to Salmonella enterica. There is limited but compelling evidence that associates irrigation water quality as a significant risk of preharvest contamination of melons. However, the potential for root uptake from water and soil and subsequent systemic transport of Salmonella into melon fruit is uncharacterized. The aim of this work was to determine whether root uptake of S. enterica results in systemic transport to fruit at high doses of applied inoculum through sub-surface drip and furrow irrigation during field production of melons. Cantaloupe and honeydew were grown under field conditions, in a silt clay loam soil using standard agronomic practices for California. An attenuated S. enterica sv. Typhimurium strain was applied during furrow irrigation and, in separate plots, buried drip-emitter lines delivered the inoculum directly into the established root zone. Contamination of the water resulted in soil contamination within furrows however Salmonella was not detected on top of the beds or around melon roots of furrow-irrigated rows demonstrating absence of detectable lateral transfer across the soil profile. In contrast, positive detection of the applied isolate occurred in soil and the rhizosphere in drip injected plots; survival of Salmonella was at least 41 days. Despite high populations of the applied bacteria in the rhizosphere, after surface disinfection, internalized Salmonella was not detected in mature melon fruit (n=485). Contamination of the applied Salmonella was detected on the rind surface of melons if fruit developed in contact with soil on the sides of the inoculated furrows. Following an unusual and heavy rain event during fruit maturation, melons collected from the central area of the beds, were shown to harbor the furrow-applied Salmonella. Delivery of Salmonella directly into the peduncle, after minor puncture wounding, resulted in detection

  11. Cholera toxin-B (ctxB) antigen expressing Salmonella Typhimurium polyvalent vaccine exerts protective immune response against Vibrio cholerae infection.

    Science.gov (United States)

    Vishwakarma, Vikalp; Sahoo, Sushree Sangita; Das, Susmita; Ray, Shilpa; Hardt, Wolf-Dietrich; Suar, Mrutyunjay

    2015-04-08

    Live attenuated vaccines are cost effective approach for preventing a broad range of infectious diseases, and thus are of great interest. However, immune-defects can predispose the patient to infections by the vaccine candidate itself. So far, few live vaccine candidates have been designed specifically for immune compromised individuals. Recently, we reported a new Salmonella Typhimurium Z234-vaccine strain (Periaswamy et al., PLoS ONE 2012;7:e45433), which was specifically attenuated in the NADPH-oxidase deficient host. In the present study, the Z234-vaccine strain was further engineered to express heterologous antigen (Vibrio cholerae toxin antigen subunit-B, i.e. CtxB) with the intention of creating a vector for simultaneous protection against Cholera and Salmonellosis. The primary aim of this study was to ensure the expression of CtxB antigen by the recombinant vaccine strain Z234-pMS101. The antigen CtxB was expressed through Z234 as a fusion protein with N-terminal signal sequence of Salmonella outer protein (SopE), an effector protein from Salmonella under the control of SopE promoter. The CtxB-expressing plasmid construct pMS101 (pM968-pSopE-ctxB) was found to be stable both in vitro and in vivo. In an oral mouse infection model, the vaccine strain Z234-pMS101 efficiently colonized the host gut. The extent of protection was confirmed after challenging the immunized hosts with live V. cholerae. Vaccinated mice showed reduced gut colonization by V. cholerae. Further assessment of immunological parameters supported the possibility of conferring effective immune response by Z234-pMS101 vaccine strain. Overall, the Z234-pMS101 vaccine strain showed potential as a promising polyvalent vaccine candidate to protect against S. Typhimurium and V. cholerae infection simultaneously.

  12. 携带兔斯氏艾美耳球虫MIC-5基因减毒鼠伤寒沙门菌活疫苗的安全性、稳定性与免疫原性%Safety, stability and immunogenicity of attenuated Salmonella typhimurium carrying MIC-5 gene of Eimeria stieda

    Institute of Scientific and Technical Information of China (English)

    孟庆玲; 乔军; 才学鹏; 闫鸿斌; 田广孚; 骆学农

    2011-01-01

    对携带兔斯氏艾美耳球虫微线蛋白-5基因(MIC-5)真核表达质粒asd-pBMIC-5-IL-15的减毒鼠伤寒沙门菌X4550(X4550/asd-pBMIC-5-IL-15)进行了安全性、稳定性与免疫原性试验.结果显示,重组菌在109CFU剂量以下对家兔安全;连续培养30代重组菌,重组表达质粒可稳定存在于X4550内,具有良好的遗传稳定性;用重组菌2次免疫动物后,既能诱导机体产生抗兔斯氏艾美耳球虫抗体,也能显著增强淋巴细胞增殖水平,抗球虫指数为164.4.试验表明,减毒沙门菌介导的兔球虫调节型DNA疫苗具有良好的安全性、稳定性和免疫原性.%The security,stability and immunogenicity trials of recombinant Salmonella typhimurium X4550 carrying rabbit's Eimeria stiedai MIC-5 gene expression plasmid asd-pBMIC-5-IL-15 (X4550/asd-pBMIO5-IL-15) was assayed in this study. The results showed that the 109 CFU inoculation dose was safe in the experimental rabbits. The recombinant plasmid existed stably in X4550 after 30 passages, which displayed a good genetic stability. After two immunizations in rabbits, the recombinant Salmonella typhimurium induced the specific antibodies against rabbit Eimeria stiedai and significantly improved the level of lymphocyte proliferation. The anti-coccidia index reached 164. 4. The results indicated that the regulation DNA vaccine mediated by Salmonella had a good security,stability and immunogenicity against rabbit Eimeria stiedai.

  13. The serologic response to Salmonella enteritidis and Salmonella typhimurium in experimentally infected chickens, followed by an indirect lipopolysaccharide enzyme-linked immunosorbent assay and bacteriologic examinations through a one-year period

    DEFF Research Database (Denmark)

    Skov, M.N.; Feld, Niels Christian; Carstensen, B.

    2002-01-01

    Three groups of 100 individually marked salmonella-free chickens were followed for a period of 53 wk. The chickens were infected as day olds by crop instillation of 101 colony-forming units: one group with Salmonella enteritidis and a second group with Salmonella typhimurium. A third group was kept...

  14. The bacterial two-hybrid system uncovers the involvement of acetylation in regulating of Lrp activity in Salmonella Typhimurium

    Directory of Open Access Journals (Sweden)

    Ran Qin

    2016-11-01

    Full Text Available Nε-lysine acetylation is an abundant and important Post-translational modification in bacteria. We used the bacterial two-hybrid system to screen the genome library of the Salmonella Typhimurium to identify potential proteins involved in acetyltransferase Pat - or deacetylase CobB-mediated acetylation. Then, the in vitro (deacetylation assays were used to validate the potential targets, such as STM14_1074, NrdF, RhaR. Lrp, a leucine-responsive regulatory protein and global regulator, was shown to interact with Pat. We further demonstrate that Lrp could be acetylated by Pat and deacetylated by NAD+-dependent CobB in vitro. Specifically, the conserved lysine residue 36 (K36 in helix-turn-helix (HTH DNA-binding domain of Lrp was acetylated. Acetylation of K36 impaired the function of Lrp through altering the affinity with the target promoter. The mutation of K36 in chromosome mimicking acetylation enhanced the transcriptional level of itself and attenuated the mRNA levels of Lrp-regulated genes including fimA, which was confirmed by yeast agglutination assay. These findings demonstrate that the acetylation regulates the DNA-binding activity of Lrp, suggesting that acetylation modification of transcription factors is a conserved regulatory manner to modulate gene expression in bacteria and eukaryotes.

  15. The Bacterial Two-Hybrid System Uncovers the Involvement of Acetylation in Regulating of Lrp Activity in Salmonella Typhimurium

    Science.gov (United States)

    Qin, Ran; Sang, Yu; Ren, Jie; Zhang, Qiufen; Li, Shuxian; Cui, Zhongli; Yao, Yu-Feng

    2016-01-01

    N𝜀-lysine acetylation is an abundant and important Post-translational modification in bacteria. We used the bacterial two-hybrid system to screen the genome library of the Salmonella Typhimurium to identify potential proteins involved in acetyltransferase Pat – or deacetylase CobB-mediated acetylation. Then, the in vitro (de)acetylation assays were used to validate the potential targets, such as STM14_1074, NrdF, RhaR. Lrp, a leucine-responsive regulatory protein and global regulator, was shown to interact with Pat. We further demonstrate that Lrp could be acetylated by Pat and deacetylated by NAD+-dependent CobB in vitro. Specifically, the conserved lysine residue 36 (K36) in helix-turn-helix (HTH) DNA-binding domain of Lrp was acetylated. Acetylation of K36 impaired the function of Lrp through altering the affinity with the target promoter. The mutation of K36 in chromosome mimicking acetylation enhanced the transcriptional level of itself and attenuated the mRNA levels of Lrp-regulated genes including fimA, which was confirmed by yeast agglutination assay. These findings demonstrate that the acetylation regulates the DNA-binding activity of Lrp, suggesting that acetylation modification of transcription factors is a conserved regulatory manner to modulate gene expression in bacteria and eukaryotes. PMID:27909434

  16. Modification of Salmonella Typhimurium motility by the probiotic yeast strain Saccharomyces boulardii.

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    Rodolphe Pontier-Bres

    Full Text Available BACKGROUND: Motility is an important component of Salmonella enterica serovar Typhimurium (ST pathogenesis allowing the bacteria to move into appropriate niches, across the mucus layer and invade the intestinal epithelium. In vitro, flagellum-associated motility is closely related to the invasive properties of ST. The probiotic yeast Saccharomyces boulardii BIOCODEX (S.b-B is widely prescribed for the prophylaxis and treatment of diarrheal diseases caused by bacteria or antibiotics. In case of Salmonella infection, S.b-B has been shown to decrease ST invasion of T84 colon cell line. The present study was designed to investigate the impact of S.b-B on ST motility. METHODOLOGY/PRINCIPAL FINDINGS: Experiments were performed on human colonic T84 cells infected by the Salmonella strain 1344 alone or in the presence of S.b-B. The motility of Salmonella was recorded by time-lapse video microscopy. Next, a manual tracking was performed to analyze bacteria dynamics (MTrackJ plugin, NIH image J software. This revealed that the speed of bacterial movement was modified in the presence of S.b-B. The median curvilinear velocity (CLV of Salmonella incubated alone with T84 decreased from 43.3 µm/sec to 31.2 µm/sec in the presence of S.b-B. Measurement of track linearity (TL showed similar trends: S.b-B decreased by 15% the number of bacteria with linear tract (LT and increased by 22% the number of bacteria with rotator tract (RT. Correlation between ST motility and invasion was further established by studying a non-motile flagella-deficient ST strain. Indeed this strain that moved with a CLV of 0.5 µm/sec, presented a majority of RT and a significant decrease in invasion properties. Importantly, we show that S.b-B modified the motility of the pathogenic strain SL1344 and significantly decreased invasion of T84 cells by this strain. CONCLUSIONS: This study reveals that S.b-B modifies Salmonella's motility and trajectory which may account for the modification

  17. Divergent roles of Salmonella pathogenicity island 2 and metabolic traits during interaction of S. enterica serovar typhimurium with host cells.

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    Stefanie U Hölzer

    Full Text Available The molecular mechanisms of virulence of the gastrointestinal pathogen Salmonella enterica are commonly studied using cell culture models of infection. In this work, we performed a direct comparison of the interaction of S. enterica serovar Typhimurium (S. Typhimurium with the non-polarized epithelial cell line HeLa, the polarized cell lines CaCo2, T84 and MDCK, and macrophage-like RAW264.7 cells. The ability of S. Typhimurium wild-type and previously characterized auxotrophic mutant strains to enter host cells, survive and proliferate within mammalian cells and deploy the Salmonella Pathogenicity Island 2-encoded type III secretion system (SPI2-T3SS was quantified. We found that the entry of S. Typhimurium into polarized cells was much more efficient than entry into non-polarized cells or phagocytic uptake. While SPI2-T3SS dependent intracellular proliferation was observed in HeLa and RAW cells, the intracellular replication in polarized cells was highly restricted and not affected by defective SPI2-T3SS. The contribution of aromatic amino acid metabolism and purine biosynthesis to intracellular proliferation was distinct in the various cell lines investigated. These observations indicate that the virulence phenotypes of S. Typhimurium are significantly affected by the cell culture model applied.

  18. Molecular beacon-based real-time PCR detection of primary isolates of Salmonella Typhimurium and Salmonella Enteritidis in environmental and clinical samples

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    Emmanuel Maria A

    2009-05-01

    Full Text Available Abstract Background A fast and simple two-step multiplex real-time PCR assay has been developed to replace the traditional, laborious Salmonella serotyping procedure. Molecular beacons were incorporated into the assay as probes for target DNA. Target sequences were regions of the invA, prot6E and fliC genes specific for Salmonella spp. Salmonella Enteritidis and Salmonella Typhimurium, respectively, the two most clinically relevant serotypes. An internal amplification positive control was included in the experiment to ensure the optimal functioning of the PCR and detect possible PCR inhibition. Three sets of primers were used for the amplification of the target sequences. The results were compared to those of the Kauffmann-White antigenic classification scheme. Results The assay was 100% sensitive and specific, correctly identifying all 44 Salmonella strains, all 21 samples of S. Enteritidis and all 17 samples of S. Typhimurium tested in this work. Therefore, the entire experiment had specificity and sensitivity of 100%. The detection limit was down to 10 copies of DNA target per 25 μl reaction. Conclusion The assay can amplify and analyse a large number of samples in approximately 8 hours, compared to the 4 to 5 days conventional identification takes, and is thus considered a very promising method for detecting the two major serotypes of Salmonella quickly and accurately from clinical and environmental samples.

  19. Effect of EDTA on Salmonella enterica serovar Typhimurium involves a component not assignable to lipopolysaccharide release.

    Science.gov (United States)

    Alakomi, H-L; Saarela, M; Helander, I M

    2003-08-01

    The effect of EDTA on Salmonella enterica serovar Typhimurium was studied in different growth phases with cells grown with or without Ca(2+) and Mg(2+) supplementation. EDTA affected the outer membrane much more strongly in the early exponential phase than in the mid- or late exponential phase, as indicated by uptake of 1-N-phenylnaphthylamine (a nonpolar hydrophobic probe, M(r) 219), and detergent (SDS) susceptibility. This effect was, however, not paralleled by LPS release (determined by measuring LPS-specific fatty acids or 14C-labelled LPS in cell-free supernatants, per a standardized cell density), which remained unchanged as a function of the growth curve. The conclusion from these results is that in the early exponential phase the effect of EDTA in S. enterica involves a component that is independent of LPS release.

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

    DEFF Research Database (Denmark)

    Issack, M. I.; Migura, Lourdes Garcia; Ramsamy, Veemala D.

    2013-01-01

    the clonality and source of Salmonella Typhimurium in Mauritius by studying human, food, and poultry isolates by pulsed-field gel electrophoresis (PFGE) and antibiotic minimum inhibitory concentration determination. Forty-nine isolates collected between 2008 and 2011 were analyzed, including 25 stool isolates...... from foodborne illness outbreaks and sporadic gastroenteritis cases, four blood isolates, one postmortem colon isolate, 14 food isolates, and five poultry isolates. All isolates were pansusceptible to the 16 antibiotics tested, except for two isolates that were resistant to sulfamethoxazole...... and trimethoprim. Overall characterization of the isolates by PFGE digested with XbaI and BlnI resulted in eight different patterns. The largest of the clusters in the composite dataset consisted of 20 isolates, including two raw chicken isolates, four poultry isolates, and nine human stool isolates from two...

  1. Carbon and nitrogen substrate utilization by archival Salmonella typhimurium LT2 cells

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    Edwards Kelly K

    2002-09-01

    Full Text Available Abstract Background A collection of over 20,000 Salmonella typhimurium LT2 mutants, sealed for four decades in agar stabs, is a unique resource for study of genetic and evolutionary changes. Previously, we reported extensive diversity among descendants including diversity in RpoS and catalase synthesis, diversity in genome size, protein content, and reversion from auxotrophy to prototrophy. Results Extensive and variable losses and a few gains of catabolic functions were observed by this standardized method. Thus, 95 catabolic reactions were scored in each of three plates in wells containing specific carbon and nitrogen substrates. Conclusion While the phenotype microarray did not reveal a distinct pattern of mutation among the archival isolates, the data did confirm that various isolates have used multiple strategies to survive in the archival environment. Data from the MacConkey plates verified the changes in carbohydrate metabolism observed in the Biolog™ system.

  2. Salmonella-Typhimurium phage types from human salmonellosis in denmark 1988 to 1993

    DEFF Research Database (Denmark)

    Wegener, Henrik Caspar; Baggesen, Dorte Lau; Gaarslev, K.

    1994-01-01

    and 194. It is concluded that phage typing, although here performed retrospectively, produces valuable epidemiological information regarding changes in the relative importance of different sources of infection in humans. It is suggested that phage typing be performed prospectively on both human and animal......A total of 989 isolates of Salmonella enterica ssp. enterica serovar Typhimurium from cases of human salmonellosis were investigated by phage typing, The isolates comprised all isolates recovered during the month of August in each of the years from 1988 to 1993. Phage typing assigned 82.......6% of the strains to 36 different definitive types, 11.9% of the strains belonged to types of unknown lysis pattern (RDNC), and 5.5% could not be typed by the phages used (NT). Three phage types (12, 66 and 110) made up approximately 50% of the isolates in each of the years investigated. During the period...

  3. Antimutagenic effects of aqueous fraction of Myristica fragrans (Houtt.) leaves on Salmonella typhimurium and Mus musculus.

    Science.gov (United States)

    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 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.

  4. Characterization of the hemA-prs region of the Escherichia coli and Salmonella typhimurium chromosomes

    DEFF Research Database (Denmark)

    Post, David A.; Hove-Jensen, Bjarne; Switzer, Robert L.

    1993-01-01

    The prs gene, encoding phosphoribosylpyrophosphate synthetase, is preceded by a leader, which is 302 bp long in Escherichia coli and 417 bp in Salmonella typhimurium. A potential open reading frame (ORF) extends across the prs promoter and into the leader. The region between the prs coding region...... direction as the prs gene with ORF 2 extending into the prs leader. Northern blot analysis showed that the prs message in E. coli was on 1.3 and 2.7 kb transcripts. The shorter transcript encoded the prs gene only, while the longer transcript also encoded the two ORFs. Thus, the prs gene is transcribed from...... two promoters, the first promoter (P1) originating upstream of ORF 1, and expressing the prs gene in a tricistronic operon and a second promoter (P2), located within the ORF 2 coding frame, which transcribes the prs gene only. The transcripts encoding prs only were 20 times as abundant...

  5. Genotoxicity of quinoxaline 1,4-dioxide derivatives in Escherichia coli and Salmonella typhimurium.

    Science.gov (United States)

    Nunoshiba, T; Nishioka, H

    1989-05-01

    The mutagenicities of 5 quinoxaline 1,4-dioxide (QdO) derivatives were tested by 2 bacterial assays using forward mutation with Escherichia coli WP2uvrA/pKM101 and reverse mutation with Salmonella typhimurium TA100 and TA98. Potent mutagenic activities of all QdOs tested were observed in both mutation assays. Mutagenicities of these compounds were varied by addition of S9 mix. Their SOS-inducing activities were examined with a 'Rec-lac test' that has been newly developed by us for detecting genotoxins. A high level of SOS-inducing activity was observed in all samples tested. These results suggest that the mutagenicity of QdOs results from the error-prone repair involved in SOS responses.

  6. Comprehensive assignment of roles for Salmonella typhimurium genes in intestinal colonization of food-producing animals.

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    Roy R Chaudhuri

    2013-04-01

    Full Text Available Chickens, pigs, and cattle are key reservoirs of Salmonella enterica, a foodborne pathogen of worldwide importance. Though a decade has elapsed since publication of the first Salmonella genome, thousands of genes remain of hypothetical or unknown function, and the basis of colonization of reservoir hosts is ill-defined. Moreover, previous surveys of the role of Salmonella genes in vivo have focused on systemic virulence in murine typhoid models, and the genetic basis of intestinal persistence and thus zoonotic transmission have received little study. We therefore screened pools of random insertion mutants of S. enterica serovar Typhimurium in chickens, pigs, and cattle by transposon-directed insertion-site sequencing (TraDIS. The identity and relative fitness in each host of 7,702 mutants was simultaneously assigned by massively parallel sequencing of transposon-flanking regions. Phenotypes were assigned to 2,715 different genes, providing a phenotype-genotype map of unprecedented resolution. The data are self-consistent in that multiple independent mutations in a given gene or pathway were observed to exert a similar fitness cost. Phenotypes were further validated by screening defined null mutants in chickens. Our data indicate that a core set of genes is required for infection of all three host species, and smaller sets of genes may mediate persistence in specific hosts. By assigning roles to thousands of Salmonella genes in key reservoir hosts, our data facilitate systems approaches to understand pathogenesis and the rational design of novel cross-protective vaccines and inhibitors. Moreover, by simultaneously assigning the genotype and phenotype of over 90% of mutants screened in complex pools, our data establish TraDIS as a powerful tool to apply rich functional annotation to microbial genomes with minimal animal use.

  7. Direct attachment of nanoparticle cargo to Salmonella typhimurium membranes designed for combination bacteriotherapy against tumors.

    Science.gov (United States)

    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

  8. Salmonella Typhimurium internalization is variable in leafy vegetables and fresh herbs.

    Science.gov (United States)

    Golberg, Dana; Kroupitski, Yulia; Belausov, Eduard; Pinto, Riky; Sela, Shlomo

    2011-01-31

    Despite washing and decontamination, outbreaks linked to consumption of fresh or minimally-processed leafy greens have been increasingly reported in recent years. In order to assure the safety of produce it is necessary to gain knowledge regarding the exact routes of contamination. Leaf internalization through stomata was previously reported as a potential route of contamination, which renders food-borne pathogens protected from washing and disinfection by sanitizers. In the present study we have examined the incidence (percentage of microscopic fields harboring ≥ 1 GFP-tagged bacteria) of Salmonella Typhimurium on the surface and underneath the epidermis in detached leaves of seven vegetables and fresh herbs. The incidence of internalized Salmonella varied considerably among the different plants. The highest incidence was observed in iceberg lettuce (81 ± 16%) and arugula leaves (88 ± 16%), while romaine (16 ± 16%) and red-lettuce (20 ± 15%), showed significantly lower incidence (P < 0.05). Internalization incidence in fresh basil was 46 ± 12%, while parsley and tomato leaves demonstrated only marginal internalization (1.9 ± 3.3% and 0.56 ± 1.36%, respectively). Internalization of Salmonella in iceberg lettuce largely varied (0-100%) through a 2 year survey, with a higher incidence occurring mainly in the summer. These results imply that Salmonella internalization occurs in several leafy vegetables and fresh herbs, other than iceberg lettuce, yet the level of internalization largely varies among plants and within the same crop. Since internalized bacteria may evade disinfection, it is of great interest to identify plants which are more susceptible to bacterial internalization, as well as plant and environmental factors that affect internalization.

  9. Coordinated Regulation of Virulence during Systemic Infection of Salmonella enterica serovar Typhimurium

    Energy Technology Data Exchange (ETDEWEB)

    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. Involvement of SPI-2-encoded SpiC in flagellum synthesis in Salmonella enterica serovar Typhimurium

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    Sugita Asami

    2009-08-01

    Full Text Available Abstract Background SpiC encoded within Salmonella pathogenicity island 2 on the Salmonella enterica serovar Typhimurium chromosome is required for survival within macrophages and systemic infection in mice. Additionally, SpiC contributes to Salmonella-induced activation of the signal transduction pathways in macrophages by affecting the expression of FliC, a component of flagella filaments. Here, we show the contribution of SpiC in flagellum synthesis. Results Quantitative RT-PCR shows that the expression levels of the class 3 fliD and motA genes that encode for the flagella cap and motor torque proteins, respectively, were lower for a spiC mutant strain than for the wild-type Salmonella. Further, this mutant had lower expression levels of the class 2 genes including the fliA gene encoding the flagellar-specific alternative sigma factor. We also found differences in flagella assembly between the wild-type strain and the spiC mutant. Many flagella filaments were observed on the bacterial surface of the wild-type strain, whereas the spiC mutant had only few flagella. The absence of spiC led to reduced expression of the FlhD protein, which functions as the master regulator in flagella gene expression, although no significant difference at the transcription level of the flhDC operon was observed between the wild-type strain and the spiC mutant. Conclusion The data show that SpiC is involved in flagella assembly by affecting the post-transcription expression of flhDC.

  11. Immunity to experimental Salmonella typhimurium infections in rats. Transfer of immunity with primed CD45RC+ and CD45RC- CD4 T-cell subpopulations

    DEFF Research Database (Denmark)

    Thygesen, P; Christensen, H B; Hougen, H P

    1996-01-01

    The protective effect of primed CD4 T cells against a lethal dose of Salmonella typhimurium was studied in Lewis rats. Primed CD4 T cells were obtained by inoculating Lewis rats with a non-lethal dose of S. typhimurium. Four weeks after the infection, spleen CD4 T cells were separated by antibody...

  12. Immunity to experimental Salmonella typhimurium infections in rats. Transfer of immunity with primed CD4+CD25high and CD4+CD25low T lymphocytes

    DEFF Research Database (Denmark)

    Thygesen, P; Brandt, L; Jørgensen, T

    1994-01-01

    The protective effect of primed CD4+ T lymphocytes against a lethal dose of 10(8) viable Salmonella typhimurium was studied in Lewis rats. Primed CD4+ T lymphocytes were obtained by inoculating Lewis rats with a non-lethal dose of 10(6) viable S. typhimurium. Four weeks after the infection, splee...

  13. [Comparison of usefulness of lipopolysaccharides extracted by phenol and trichloroacetic acid from Salmonella Typhimurium and Enteritidis for serodiagnosis of salmonelosis].

    Science.gov (United States)

    Rastawicki, Waldemar; Rokosz, Natalia; Jagielski, Marek

    2011-01-01

    Salmonella Typhimurium and Salmonella Enteritidis are the two predominant serogroups, responsible for about 80% of all human cases of salmonelosis in Poland. Therefore we compared the usefulness of lipopolysaccharides antigens extracted by phenol (Westphal method) and trichloroacetic acid (Boivine method) from Salmonella Typhimurium and Enteritidis in ELISA method for the determination of antibodies. We used one home - made LPS antigen and two others commercially available antigens from SIGMA - Aldrich. Our study showed that the presence of antibodies was found in 35 (74.5%) sera from 47 samples from patients with suspected salmonelosis. There was no significant statistical differences of frequency of appearance of antibodies to all three Salmonella antigens in sera from patients with salmonelosis and in sera from control group. This study showed that all three antigens are useful for determination of IgA, IgG, IgM antibodies for Salmonella serogroup B and D in routine serological diagnosis of salmonelosis. However, it should be considered possibility of cross-reaction between LPS antigen of Salmonella and antibodies to Yersinia enterocolitica which could be correlated with similarity between somatic antigens of these two pathogens.

  14. Effects of indole on drug resistance and virulence of Salmonella enterica serovar Typhimurium revealed by genome-wide analyses

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    Nikaido Eiji

    2012-05-01

    Full Text Available Abstract 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.

  15. Transmission routes of Salmonella Typhimurium DT 104 between 14 cattle and pig herds in Denmark demonstrated by molecular fingerprinting

    DEFF Research Database (Denmark)

    Langvad, B.; Skov, M.N.; Rattenborg, E.;

    2006-01-01

    Aims: Salmonella Typhimurium DT 104 is generally assumed to be spread by contact between live animals, e.g. by trading. The aim of the present study was to assess the importance of other routes of transmission in the dissemination of this bacterium. Methods and Results: An outbreak among 14 cattle...... electrophoresis (PFGE) and the plasmid profiles of isolates obtained by continuous sampling over a period of almost 3 years. Conclusions: The study indicated that other routes might play an important role, than the trading of live animals, in the spread of S. Typhimurium DT 104 among livestock. Significance...

  16. A critical appraisal of the phene-plate biochemical fingerprinting system for epidemiological subtyping of Salmonella typhimurium

    DEFF Research Database (Denmark)

    On, S.L.W.; Baggesen, Dorte Lau

    1996-01-01

    The efficacy and reproducibility of the Phene-Plate (PhP) system (Biosys Inova, Stockholm, Sweden) for biochemical fingerprinting of Salmonella typhimurium was investigated. Duplicate and replicate assays on 40 epidemiologically related and unrelated strains were performed in two batches of PhP-48......P-types which are epidemiologically unjustified, (ii) tests currently recommended for PhP-typing S. typhimurium may be somewhat unstable and not satisfactory for fingerprinting purposes, (iii) caution must be exercised when comparing data from different batches of PhP-48 plates, and (iv) best results...

  17. Interdigitated microelectrode (IME) impedance sensor for the detection of viable Salmonella typhimurium.

    Science.gov (United States)

    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.

  18. Structure of Salmonella typhimurium OMP synthase in a complete substrates complex

    Science.gov (United States)

    Grubmeyer, Charles; Hansen, Michael Riis; Fedorov, Alexander A.; Almo, Steven C.

    2012-01-01

    Dimeric Salmonella typhimurium orotate phosphoribosyltransferase (OMP synthase, E.C. 2.4.2.10), a key enzyme in de novo pyrimidine nucleotide synthesis, has been co-crystallized in a complete substrate complex of E•MgPRPP•orotate, and the structure solved to 2.2 Å resolution. This structure resembles that for Saccharomyces cerevisiae OMP synthase in showing a dramatic and asymmetric reorganization around the active site-bound ligands, but shares the same basic topology previously observed in complexes of OMP synthase from S. typhimurium and Escherichia coli. The catalytic loop (residues 99–109) contributed by subunit A is reorganized to close the active site situated in subunit B and to sequester it from solvent. Furthermore, the overall structure of subunit B is more compact, due to movements of the amino-terminal hood and elements of the core domain. The catalytic loop of subunit B remains open and disordered, and subunit A retains the more relaxed conformation observed in loop-open S. typhimurium OMP synthase structures. A non-proline cis-peptide formed between Ala71 and Tyr72 is seen in both subunits. The loop-closed catalytic site of subunit B reveals that both the loop and the hood interact directly with the bound pyrophosphate group of PRPP. In contrast to dimagnesium hypoxanthine-guanine phosphoribosyltransferases, OMP synthase contains a single catalytic Mg2+ in the closed active site. The remaining pyrophosphate charges of PRPP are neutralized by interactions with Arg99A, Lys100B, Lys103A, and His105A. The new structure confirms the importance of loop movement in catalysis by OMP synthase, and identifies several additional movements that must be accomplished in each catalytic cycle. A catalytic mechanism based on enzymic and substratea-ssisted stabilization of the previously documented oxocarbenium transition state structure is proposed. PMID:22531064

  19. Stromal IFN-γR-signaling modulates goblet cell function during Salmonella Typhimurium infection.

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    Pascal Songhet

    Full Text Available Enteropathogenic bacteria are a frequent cause of diarrhea worldwide. The mucosal defenses against infection are not completely understood. We have used the streptomycin mouse model for Salmonella Typhimurium diarrhea to analyze the role of interferon gamma receptor (IFN-γR-signaling in mucosal defense. IFN-γ is known to contribute to acute S. Typhimurium diarrhea. We have compared the acute mucosal inflammation in IFN-γR(-/- mice and wild type animals. IFN-γR(-/- mice harbored increased pathogen loads in the mucosal epithelium and the lamina propria. Surprisingly, the epithelium of the IFN-γR(-/- mice did not show the dramatic "loss" of mucus-filled goblet cell vacuoles, a hallmark of the wild type mucosal infection. Using bone marrow chimeric mice we established that IFN-γR-signaling in stromal cells (e.g. goblet cells, enterocytes controlled mucus excretion/vacuole loss by goblet cells. In contrast, IFN-γR-signaling in bone marrow-derived cells (e.g. macrophages, DCs, PMNs was required for restricting pathogen growth in the gut tissue. Thus IFN-γR-signaling influences different mucosal responses to infection, including not only pathogen restriction in the lamina propria, but, as shown here, also goblet cell function.

  20. Actin restructuring during Salmonella typhimurium infection investigated by confocal and super-resolution microscopy

    Science.gov (United States)

    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.

  1. Actin restructuring during Salmonella typhimurium infection investigated by confocal and super-resolution microscopy.

    Science.gov (United States)

    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.

  2. Mutagenic metabolite synthesized by Salmonella typhimurium grown in the presence of azide is azidoalanine

    Energy Technology Data Exchange (ETDEWEB)

    Owais, W.M.; Rosichan, J.L.; Ronald, R.C.; Kleinhofs, A.; Nilan, R.A.

    1983-01-01

    A mutagenic azide metabolite was purified from the medium in which Salmonella typhimurium cells were grown in the presence of azide. This metabolite was identified to be azidoalanine based on infrared and mass spectroscopy and elemental analysis. This compound appeared to be identical to the mutagenic compound synthesized in vitro from azide and O-acetylserine by partially purified O-acetylserine sulfhydrylase. The metabolite (azidoalanine) mutagenic efficiency and spectrum in S. typhimurium was similar to that of inorganic azide. The compounds 2-azidoethylamine, 2-bromoethylamine, 3-bromopropionic acid and N-(azidomethyl) phthalimide were also mutagenic with a similar spectrum to azide and azidolanine, but with lower efficienty. The compounds 3-azidopropylamine, 4-azidobutylamine, 3-chloroalanine and ethylamine were only weakly or nonmutagenic. Numerous other chloro, bromo and azido phthalimide derivatives tested were nonmutagenic. It is suggested that the lack of azide mutagenicity (and perhaps carcinogenicity) in mammalian cells may be due to their inability to convert azide to azidoalanine. 36 references, 3 figures, 2 tables.

  3. Complex regulatory network encompassing the Csr, c-di-GMP and motility systems of Salmonella Typhimurium.

    Science.gov (United States)

    Jonas, Kristina; Edwards, Adrianne N; Ahmad, Irfan; Romeo, Tony; Römling, Ute; Melefors, Ojar

    2010-02-01

    Bacterial survival depends on the ability to switch between sessile and motile lifestyles in response to changing environmental conditions. In many species, this switch is governed by (3'-5')-cyclic-diguanosine monophosphate (c-di-GMP), a signalling molecule, which is metabolized by proteins containing GGDEF and/or EAL domains. Salmonella Typhimurium contains 20 such proteins. Here, we show that the RNA-binding protein CsrA regulates the expression of eight genes encoding GGDEF, GGDEF-EAL and EAL domain proteins. CsrA bound directly to the mRNA leaders of five of these genes, suggesting that it may regulate these genes post-transcriptionally. The c-di-GMP-specific phosphodiesterase STM3611, which reciprocally controls flagella function and production of biofilm matrix components, was regulated by CsrA binding to the mRNA, but was also indirectly regulated by CsrA through the FlhDC/FliA flagella cascade and STM1344. STM1344 is an unconventional (c-di-GMP-inactive) EAL domain protein, recently identified as a negative regulator of flagella gene expression. Here, we demonstrate that CsrA directly downregulates expression of STM1344, which in turn regulates STM3611 through fliA and thus reciprocally controls motility and biofilm factors. Altogether, our data reveal that the concerted and complex regulation of several genes encoding GGDEF/EAL domain proteins allows CsrA to control the motility-sessility switch in S. Typhimurium at multiple levels.

  4. Structure Prediction of Outer Membrane Protease Protein of Salmonella typhimurium Using Computational Techniques

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    Rozina Tabassum

    2016-03-01

    Full Text Available Salmonella typhimurium, a facultative gram-negative intracellular pathogen belonging to family Enterobacteriaceae, is the most frequent cause of human gastroenteritis worldwide. PgtE gene product, outer membrane protease emerges important in the intracellular phases of salmonellosis. The pgtE gene product of S. typhimurium was predicted to be capable of proteolyzing T7 RNA polymerase and localize in the outer membrane of these gram negative bacteria. PgtE product of S. enterica and OmpT of E. coli, having high sequence similarity have been revealed to degrade macrophages, causing salmonellosis and other diseases. The three-dimensional structure of the protein was not available through Protein Data Bank (PDB creating lack of structural information about E protein. In our study, by performing Comparative model building, the three dimensional structure of outer membrane protease protein was generated using the backbone of the crystal structure of Pla of Yersinia pestis, retrieved from PDB, with MODELLER (9v8. Quality of the model was assessed by validation tool PROCHECK, web servers like ERRAT and ProSA are used to certify the reliability of the predicted model. This information might offer clues for better understanding of E protein and consequently for developmet of better therapeutic treatment against pathogenic role of this protein in salmonellosis and other diseases.

  5. Hierarchical involvement of various GGDEF domain proteins in rdar morphotype development of Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Kader, Abdul; Simm, Roger; Gerstel, Ulrich; Morr, Michael; Römling, Ute

    2006-05-01

    GGDEF and EAL domain proteins are involved in the turnover of the novel secondary messenger cyclic-di(3'-->5')-guanylic acid (c-di-GMP) in many bacteria. In this work the role of the 12 GGDEF domain proteins encoded by the Salmonella enterica serovar Typhimurium (S. Typhimurium) chromosome in rdar morphotype development was investigated. Previously, it was shown that the GGDEF domain protein AdrA activated the biosynthesis of cellulose by production of c-di-GMP. Enhancement of the c-di-GMP levels by overexpression of the GGDEF domain protein AdrA did lead to the activation of curli fimbriae biosynthesis through the elevated expression of CsgD and CsgA. Although knock-out of the chromosomal copy of adrA influenced CsgA expression, CsgD expression was not altered, although more than half of the total cellular c-di-GMP was produced by AdrA at 16 h of growth. On the other hand, chromosomally encoded GGDEF-EAL domain proteins STM2123 and STM3388 were required to additively activate CsgD expression on a transcriptional and post-transcriptional level. Enhanced c-di-GMP levels did overcome temperature regulation of rdar morphotype expression by activation of curli fimbriae as well as cellulose biosynthesis through CsgD expression. Thus in the regulatory cascade leading to rdar morphotype expression c-di-GMP activates several subsequent steps in the network.

  6. No beneficial effects evident for Enterococcus faecium NCIMB 10415 in weaned pigs infected with Salmonella enterica serovar Typhimurium DT104.

    Science.gov (United States)

    Kreuzer, Susanne; Janczyk, Pawel; Assmus, Jens; Schmidt, Michael F G; Brockmann, Gudrun A; Nöckler, Karsten

    2012-07-01

    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.

  7. Salmonella typhimurium strain SL7207 induces apoptosis and inhibits the growth of HepG2 hepatoma cells in vitro and in vivo

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    Baowei Li

    2012-12-01

    Full Text Available Salmonella typhimurium is probably most extensively studied tumor-targeting bacteria and SL7207 is one of its attenuated strains. SL7207 was first made for bacterial vaccine development and its therapeutic efficacy and safety for hepatocellular carcinoma has not been characterized. In this study, the inhibitory ability of SL7207-lux on human hepatoma HepG2 cells was tested in vitro and in vivo. A bacterial luminescent gene cluster (lux CDABE was transfected into SL7207 to better monitor the invasion of the bacteria. The results show that SL7207-lux can rapidly enter HepG2 cells and localize in the cytoplasm. This invasion represses cell proliferation and induces apoptosis. In vivo real-time invasion studies showed that the bacteria gradually accumulate in the tumor. This enrichment was confirmed by anatomic observation at 5 days after inoculation. About 40% of tumor growth was inhibited by SL7207-lux at 34 days post-treatment without significant loss of body weight. The area of necrosis of tumor tissue was clearly increased in the treated group. Bacterial quantification showed that the number of colony-forming units per gram of bacteria within tumor tissue was approximately 1000-fold higher than that of liver and spleen. These data suggest that attenuated S. typhimurium strain SL7207 has potential for the treatment of cancers.

  8. Cloning and sequencing of hfq (host factor required for synthesis of bacteriophage Q beta RNA gene of Salmonella Typhimurium isolated from poultry

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    Parthasarathi Behera

    2015-05-01

    Full Text Available Aim: The aim was to clone and sequence hfq gene of Salmonella Typhimurium strain PM-45 and compare its sequence with hfq gene of other serovar of Salmonella. Materials and Methods: Salmonella Typhimurium strain PM-45 was procured from the G. B. Pant University of Agriculture and Technology, Pantnagar, India. The genomic DNA was isolated from Salmonella Typhimurium. Hfq gene was polymerase chain reaction (PCR amplified from the DNA using specific primers, which was subsequently cloned into pET32a vector and transformed into Escherichia coli BL21 pLys cells. The recombinant plasmid was isolated and subjected to restriction enzyme digestion as well as PCR. The clone was then sequenced. The sequence was analyzed and submitted in GenBank. Results: PCR produced an amplicon of 309 bp. Restriction digestion of the recombinant plasmid released the desired insert. The hfq sequence shows 100% homology with similar sequences from other Salmonella Typhimurium isolates. Both nucleotide and amino acid sequences are highly conserved. The submitted sequence is having Genbank accession no KM998764. Conclusion: Hfq, the hexameric RNA binding protein is one of the most important post-transcriptional regulator of bacteria. The sequence of hfq gene of Salmonella Typhimurium is highly conserved within and between Salmonella enterica serovars. This gene sequence is probably under heavy selection pressure to maintain the conformational integrity of its product in spite of its being not a survival gene.

  9. Comparative effect of methioninyl adenylate on the growth of Salmonella typhimurium and Pseudomonas aeruginosa.

    Science.gov (United States)

    Enouf, J; Laurence, F; Farrugia, G; Blanchard, P; Robert-Gero, M

    1976-10-11

    The bacteriostatic effect of methioninyl adenylate(MAMP)--a specific inhibitor of the enzyme methionyl-tRNA synthetase--was investigated on Salmonella typhimurium and Pseudomonas aeruginosa. 0.1 mM of this molecule added to the culture, inhibits the growth of S. typhimurium. The inhibition is specifically reversible by 0.1 mM L-methionine. In the same conditions even 1-2 mM MAMP has a very slight effect on the growth rate of P. aeruginosa and only during the first two generations. The same observation was made with the two other members of the fluorescens group P.fluorescens and P.putida. The growth rate of P. testosteroni with 1 mM MAMP in the medium is similar to the growth rate of P. aeruginosa but the other member of the acidovorans group P. acidovorans is much more affected by the smae concentration of the inhibitor. --P. multivorans is inhibited by MAMP like P. acidovorans but with a somewhat higher yield at the end of the culture. --MAMP has no effect on P. alcaligenes. The possible reasons for the weak bacteriostatic effect of MAMP on P. aeruginosa were investigated. It was established that the inhibitor enters the cells and is not used as a carbon and energy source. The intracellular methionine concentration in S. typhimurium and in P. aeruginosa is about the same and does not increase when bacteria are cultivated with MAMP. The MTS of the two microorganisms is inhibited by MAMP in vitro to about the same extent. Furthermore the tRNAmet from P. aeruginosa are fully acylated after 3 to 4 generations with this compound. Nevertheless MAMP elicits higher MTS activity in P. aeruginosa and in P. acidovorans after 1 h of incubation. The most striking difference between S. typhimurium and P. aeruginosa is that the intra and extracellular level of 5'phosphodiesterase which degrades MAMP is 10-20 fold higher in the second than in the first species.

  10. Igg Subclasses Targeting the Flagella of Salmonella enterica Serovar Typhimurium Can Mediate Phagocytosis and Bacterial Killing

    Science.gov (United States)

    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

  11. Inducers and autoinducers on Salmonella enterica serovar Typhimurium motility, growth and gene expression

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    Rita de Cássia dos Santos da Conceição

    2015-12-01

    Full Text Available Genus Salmonella bacteria are among the major pathogenic microorganisms in food. This bacterium pathogenicity is related to a number of virulence factors, among which its flagella. Flagellum expression is one of the virulence factors modulated by Quorum Sensing. Epinephrine produced by mammals uses the same signaling pathway of the 3 bacteria autoinducer. This study evaluated the effect of molecules inducer (epinephrine and autoinducers (autoinducer 2 and autoinducer 3 and their association with the motility, growth and expression genes flhC, fliA, fliY, motA, motB e fliC of Salmonella Typhimurium (ST. Initially, ST was inoculated in BHI. Then, motility assays, growth curves and gene expression were performed by testing different concentrations of epinephrine (50, 125, 250, 500µM, conditioned medium (10 and 50% and a combination of these. ST was exposed to different concentrations of epinephrine, conditioned medium and an association of both. Following, motility assays, bacterial growth and gene expression were performed. The results obtained showed that the combination of 500uM epinephrine with 50% conditioned medium increased ST bacterial motility by increasing the expression of genes involved in flagellum assembly.

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

    Science.gov (United States)

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

    2004-11-01

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

  13. Saccharomyces boulardii modifies Salmonella typhimurium traffic and host immune responses along the intestinal tract.

    Directory of Open Access Journals (Sweden)

    Rodolphe Pontier-Bres

    Full Text Available Salmonella enterica serovar Typhimurium (ST is an enteropathogenic Gram-negative bacterium that causes infection following oral ingestion. ST spreads rapidly along the gastrointestinal tract (GIT and invades the intestinal epithelium to ultimately reach internal body organs. The probiotic yeast Saccharomyces boulardii BIOCODEX (S.b-B is prescribed for prophylaxis of diarrheal infectious diseases. We previously showed that S.b-B prevents weight loss in ST-infected mice and significantly decreases bacterial translocation to the spleen and liver. This study was designed to investigate the effect of S.b-B on ST migration along the GIT and the impact of the yeast on the host's early innate immune responses. Bioluminescent imaging (BLI was used to evaluate the effect of S.b-B on the progression of luminescent Salmonella Typhimurium (ST-lux in the GIT of mice pretreated with streptomycin. Photonic emission (PE was measured in GIT extracts (stomach, small intestine, cecum and colon at various time periods post-infection (PI. PE analysis revealed that, 45 min PI, ST-lux had migrated slightly faster in the mice treated with S.b-B than in the untreated infected animals. At 90 min PI, ST-lux had reached the cecum in both groups of mice. Adhesion of ST to S.b-B was visualized in the intestines of the mice and probably accounts for (1 the faster elimination of ST-lux in the feces, and (2 reduced translocation of ST to the spleen and liver. In the early phase of infection, S.b-B also modifies the host's immune responses by (1 increasing IFN-γ gene expression and decreasing IL-10 gene expression in the small intestine, and (2 elevating both IFN-γ, and IL-10 mRNA levels in the cecum. BLI revealed that S.b-B modifies ST migration and the host immune response along the GIT. Study findings shed new light on the protective mechanisms of S.b-B during the early phase of Salmonella pathogenesis.

  14. Salmonella enterica serovar Typhimurium BaeSR two-component system positively regulates sodA in response to ciprofloxacin.

    Science.gov (United States)

    Guerrero, P; Collao, B; Álvarez, R; Salinas, H; Morales, E H; Calderón, I L; Saavedra, C P; Gil, F

    2013-10-01

    In response to antibiotics, bacteria activate regulatory systems that control the expression of genes that participate in detoxifying these compounds, like multidrug efflux systems. We previously demonstrated that the BaeSR two-component system from Salmonella enterica serovar Typhimurium (S. Typhimurium) participates in the detection of ciprofloxacin, a bactericidal antibiotic, and in the positive regulation of mdtA, an efflux pump implicated in antibiotic resistance. In the present work, we provide further evidence for a role of the S. Typhimurium BaeSR two-component system in response to ciprofloxacin treatment and show that it regulates sodA expression. We demonstrate that, in the absence of BaeSR, the transcript levels of sodA and the activity of its gene product are lower. Using electrophoretic mobility shift assays and transcriptional fusions, we demonstrate that BaeR regulates sodA by a direct interaction with the promoter region.

  15. Effects of irradiation and fumaric acid treatment on the inactivation of Listeria monocytogenes and Salmonella typhimurium inoculated on sliced ham

    Science.gov (United States)

    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.

  16. Synergistic Antibacterial Effect of Silver Nanoparticles Combined with Ineffective Antibiotics on Drug Resistant Salmonella typhimurium DT104.

    Science.gov (United States)

    McShan, Danielle; Zhang, Ying; Deng, Hua; Ray, Paresh C; Yu, Hongtao

    2015-01-01

    Synergistic antibacterial activity of combined silver nanoparticles (AgNPs) with tetracycline (polykeptide), neomycin (aminoglycoside), and penicillin (β-lactam) was tested against the multidrug resistant bacterium Salmonella typhimurium DT104. Dose-dependent inhibition of Salmonella typhimurium DT104 growth is observed for tetracycline-AgNPs and neomycin-AgNPs combination with IC50 of 0.07 μg/mL and 0.43 μg/mL, respectively. There is no inhibition by the penicillin-AgNPs combination. These results suggest that the combination of the ineffective tetracycline or neomycin with AgNPs effectively inhibits the growth of this bacterium. The synergistic antibacterial effect is likely due to enhanced bacterial binding by AgNPs assisted by tetracycline or neomycin, but not by penicillin.

  17. Real-time reverse transcriptase PCR for the rapid and sensitive detection of Salmonella typhimurium from pork.

    Science.gov (United States)

    Techathuvanan, Chayapa; Draughon, Frances Ann; D'Souza, Doris Helen

    2010-03-01

    Reverse transcriptase PCR (RT-PCR) detects the presence of mRNA and has a greater potential for detecting viable pathogens than do DNA-based PCR assays, with improved speed and sensitivity compared with traditional methods. Our objective was to rapidly and sensitively detect Salmonella Typhimurium from pork within two 8-h work shifts using a SYBR Green I real-time RT-PCR (rt-RT-PCR) assay. Pork chop and sausage samples (25 g) were inoculated with 10(8) to 10(0) CFU of Salmonella Typhimurium and stomached in 225 ml of tetrathionate broth. Serial dilutions were spread plated on xylose lysine Tergitol 4 agar either immediately or after 10 h of selective preenrichment or preenrichment followed by 12 h of selective enrichment (for stressed cells) at 37 degrees C for standard cultural enumeration. RNA was extracted using the TRIzol method. The rt-RT-PCR assay was carried out in a Bio-Rad iCycler using a SYBR Green I one-step RT-PCR kit and Salmonella specific invA gene primers with an internal amplification control (IAC). The PCR was followed by melting temperature (T(m)) analysis to determine specific Salmonella invA (T(m) = 87.5 degrees C) and IAC (T(m) = 82 degrees C) products. Improved Salmonella detection up to 10(1) CFU/25 g of pork and 10(0) CFU/25 g of sausages was obtained after 10 h of enrichment within approximately 24 h. Even without enrichment, Salmonella could be detected from both pork chop and sausage at 10(6) CFU/25 g within 1 day. This robust rt-RT-PCR detects and confirms Salmonella in pork within approximately 24 h and thus is significantly faster than traditional methods that take >/=1 week. This assay shows promise for routine testing and monitoring of Salmonella by the pork industry.

  18. Salmonella typhimurium's transthyretin-like protein is a host-specific factor important in fecal survival in chickens.

    Directory of Open Access Journals (Sweden)

    Sarah C Hennebry

    Full Text Available The transthyretin-like protein (TLP from Salmonella enterica subspecies I is a periplasmic protein with high level structural similarity to a protein found in mammals and fish. In humans, the protein homologue, transthyretin, binds and carries retinol and thyroxine, and a series of other, unrelated aromatic compounds. Here we show that the amino acid sequence of the TLP from different species, subspecies and serovars of the Salmonella genus is highly conserved and demonstrate that the TLP gene is constitutively expressed in S. Typhimurium and that copper and other divalent metal ions severely inhibit enzyme activity of the TLP, a cyclic amidohydrolase that hydrolyses 5-hydroxyisourate (5-HIU. In order to determine the in vivo role of the S. Typhimurium TLP, we constructed a strain of mouse-virulent S. Typhimurium SL1344 bearing a mutation in the TLP gene (SL1344 ΔyedX. We assessed the virulence of this strain via oral inoculation of mice and chickens. Whilst SL1344 ΔyedX induced a systemic infection in both organisms, the bacterial load detected in the faeces of infected chickens was significantly reduced when compared to the load of S. Typhimurium SL1344. These data demonstrate that the TLP gene is required for survival of S. Typhimurium in a high uric acid environment such as chicken faeces, and that metabolic traits of Salmonellae in natural and contrived hosts may be fundamentally different. Our data also highlight the importance of using appropriate animal models for the study of bacterial pathogenesis especially where host-specific virulence factors or traits are the subject of the study.

  19. Aggregation via the red, dry, and rough morphotype is not a virulence adaptation in Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

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

    2008-03-01

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

  20. Estimating the number of undetected multi-resistant Salmonella Typhimurium DT104 infected pig herds in Denmark

    DEFF Research Database (Denmark)

    Rugbjerg, Helene; Wingstrand, Anne; Hald, Tine;

    2004-01-01

    In Denmark, the detection of multi-resistant Salmonella Typhimurium DT104 (MRDT104)-infected pig herds relies on the national Salmonella surveillance programme at the farm and slaughterhouse levels of production. With the surveillance sampling protocol and the diagnostic methods currently used...... with MRDT104 from 1 August 2001 till 31 July 2002 (90% CI [63, 228]). In comparison, 33 (32%) infected herds were detected in this period. The predicted proportion of undetected herds varied considerably with herd type. We infer that the proportion of detected MRDT104 infected herds depended...

  1. DsbL and DsbI contribute to periplasmic disulfide bond formation in Salmonella enterica serovar Typhimurium

    OpenAIRE

    Lin, Dongxia; Kim, Byoungkwan; Slauch, James M.

    2009-01-01

    Disulfide bond formation in periplasmic proteins is catalysed by the DsbA/DsbB system in most Gram-negative bacteria. Salmonella enterica serovar Typhimurium also encodes a paralogous pair of proteins to DsbA and DsbB, DsbL and DsbI, respectively, downstream of a periplasmic arylsulfate sulfotransferase (ASST). We show that DsbL and DsbI function as a redox pair contributing to periplasmic disulfide bond formation and, as such, affect transcription of the Salmonella pathogenicity island 1 (SP...

  2. Glutathione: an intracellular and extracellular protective agent in Salmonella typhimurium and Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. PCR detection of Salmonella typhimurium in pharmaceutical raw materials and products contaminated with a mixed bacterial culture using the BAX system.

    Science.gov (United States)

    Jimenez, L; Scalici, C; Smalls, S; Bosko, Y; Ignar, R

    2001-01-01

    The BAX system, a PCR-based assay, was evaluated for detecting Salmonella typhimurium in pharmaceutical raw materials and products contaminated with mixed bacterial cultures of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium. Artificially contaminated samples were preenriched in lactose broth with and without Tween 20. After preenrichment, samples were analyzed by PCR and standard methods. Ten of 25 samples did not show presence of the specific Salmonella spp. 740-base pair DNA fragment. However, S. typhimurium was isolated and identified by standard methods from all 25 samples. To optimize S. typhimurium detection in PCR negative samples, lactose broth was replaced by buffered peptone water (BPW) as the preenrichment broth. When BPW was used, all 10 samples were PCR positive. BPW enrichments increased S. typhimurium growth resulting in rapid PCR detection. The presence of non-Salmonella bacteria influenced the performance of the PCR-based assay. Optimization of S. typhimurium PCR detection in mixed culture required the use of different preenrichment broths. However, the BAX system detected S. typhimurium within 27 hours while standard methods required 5-7 days.

  4. The architecture and ppGpp-dependent expression of the primary transcriptome of Salmonella Typhimurium during invasion gene expression

    Directory of Open Access Journals (Sweden)

    Ramachandran Vinoy K

    2012-01-01

    Full Text Available Abstract 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.

  5. Chimeric flagellin expressed by Salmonella typhimurium induces an ESAT-6-specific Th 1-type immune response and CTL effects following intranasal immunization

    Institute of Scientific and Technical Information of China (English)

    Hui Zhang; Liu Liu; Ke Wen; Jinlin Huang; Shizhong Geng; Junsong Shen; Zhiming Pan; Xinan Jiao

    2011-01-01

    The flagellin component FliC of Salmonella typhimurium is capable of activating the innate immune system via specific interactions with TLR5 and can also act as a carrier of foreign antigen to elicit antigen-specific immune responses.Thus,we constructed an attenuated Salmonella strain SL5928(fliC/esat) expressing chimeric flagellin that contained the ESAT-6 antigen coding sequence of Mycobacterium tuberculosis inserted into the highly variable region of the Salmonella flagellin coding gene fliCi.The chimeric flagellin functioned normally,as demonstrated using a flagella swarming assay and electron microscopy.To analyze the effects of chimeric flagellin,the cell-mediated immune response and cytotoxic T lymphocyte (CTL) effects specific for ESAT-6antigen were tested after intranasal immunization of mice with flagellated Salmonella SL5928(fliC/esat).The results showed that SL5928(fliC/esat) intranasal immunization can strongly elicit an ESAT-6-specific T helper (Th) 1-type immune response in mucosal lymphoid tissues,such as nasopharynx-associated lymph nodes,lung and Peyer's patches,and a Th 1/Th2 response was elicited in spleen and mesenteric lymph nodes.Furthermore,intranasal immunization of SL5928(fliC/esat) produced efficient CTL effects,as demonstrated using a 5-and 6-carboxyfluorescein diacetate succinimidyl ester (CFSE) assay.Thus,our study revealed that Salmonella flagellin acts as a carrier for foreign antigen and triggers strong Th 1 and CTL responses during intranasal immunization.Chimeric flagellin is potentially an effective strategy for the development of novel vaccines against tuberculosis in humans and animals.

  6. QUANTIFICATION OF Salmonella Typhimurium REDUCTION DURING COLD STORAGE OF RAW SHRIMPS IN THE PRESENCE OF SODIUM METABISULFITE [Kuantifikasi Reduksi Salmonella Typhimurium pada Udang Segar selama Penyimpanan Dingin dengan Penambahan Natrium Metabisulfit

    Directory of Open Access Journals (Sweden)

    Andiarto Yanuardi3

    2012-12-01

    Full Text Available Prediction of bacterial growth, survival or reduction in food matrices is needed for microbiological risk assessment. The survival of Salmonella Typhimurium on surfaces of raw shrimps at low temperature was studied, in the presence of sodium metabisulfite which is often used to prevent melanosis. The growth and/or reduction rates were quantified using DMFit software with Baranyi model and or linear model. The result showed that without sodium metabisulfite (control, when the initial level was high (105 CFU/ml, S. Typhimurium grew with a lag phase of 51.99±7.46 h and a growth rate of 0.01±0.002 log CFU.ml-1.h-1 on raw shrimps during storage at 8±2°C. When 1.5% (w/w sodium metabisulfite, a maximum level that often used to prevent melanosis, was added under the same condition, the number of S. Typhimurium was reduced for 5 log CFU/ml after 5 days, with a reduction rate of -0.03±0.001 log CFU.ml-1.h-1. This study indicated that Baranyi model can be used to predict the growth of S. Typhimurium on raw shrimp at low temperature, when sodium metabisulfite is absent. However, when sodium metabisulfite is present, at least 0.4% as found in this study, the reduction of S. Typhimurium can be predicted using a simple linear model.

  7. Emergence of Salmonella typhimurium definitive type 104 (DT104) as an important cause of salmonellosis in horses in Ontario.

    OpenAIRE

    Weese, J. S.; Baird, J D; Poppe, C; Archambault, M.

    2001-01-01

    Salmonella Typhimurium definitive type 104 (DT104) has emerged as a common cause of salmonellosis in humans and cattle, yet previous reports involving horses are sparse. This study reports the emergence of DT104 as an important pathogen in horses in Ontario. The first clinical case of DT104 infection at the Ontario Veterinary College was identified in 1997. Seventeen cases of DT104-associated salmonellosis were identified between 1997 and 2000. In 2000, 12 of 13 cases of salmonellosis were du...

  8. Atmospheric Cold Plasma Inactivation of Escherichia Coli, Salmonella Enterica Serovar Typhimurium and Listeria Monocytogenes Inoculated on Fresh Produce

    OpenAIRE

    2014-01-01

    Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were...

  9. A functional cra gene is required for Salmonella enterica serovar typhimurium virulence in BALB/c mice

    DEFF Research Database (Denmark)

    Allen, J. H.; Utley, M.; Van den Bosch, H.;

    2000-01-01

    A minitransposon mutant of Salmonella enterica serovar Typhimurium SR-11, SR-11 Fad(-), is unable to utilize gluconeogenic substrates as carbon sources and is avirulent and immunogenic when administered perorally to BALB/c mice (M. J. Utley et al., FEMS Microbiol. Lett., 163:129-134, 1998). Here......, evidence is presented that the mutation in SR-11 Fad(-) that renders the strain avirulent is in the cra gene, which encodes the Cra protein, a regulator of central carbon metabolism....

  10. Effect of grinding intensity and feed physical form on in vitro adhesion of Salmonella Typhimurium and mannose residues in intestinal mucus receptors for salmonellae.

    Science.gov (United States)

    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.

  11. Investigation and management of an outbreak of Salmonella Typhimurium DT8 associated with duck eggs, Ireland 2009 to 2011.

    LENUS (Irish Health Repository)

    Garvey, P

    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.

  12. Surface Display of Domain Ⅲ of Japanese Encephalitis Virus E Protein on Salmonella Typhimurium by Using an Ice Nucleation Protein

    Institute of Scientific and Technical Information of China (English)

    Jian-lin Dou; Tao Jing; Jing-jing Fan; Zhi-ming Yuan

    2011-01-01

    A bacterial cell surface display technique based on an ice nucleation protein has been employed for the development of live vaccine against viral infection.Due to its ubiquitous ability to invade host cells,Salmonella typhimurium might be a good candidate for displaying viral antigens.We demonstrated the surface display of domain III of Japanese encephalitis virus E protein and the enhanced green fluorescent protein on S.typhimurium BRD509 using the ice nucleation protein.The effects of the motif in the ice nucleation protein on the effective display of integral protein were also investigated.The results showed that display motifs in the protein can target integral foreign protein on the surface of S.typhimurium BRD509.Moreover,recombinant strains with surface displayed viral proteins retained their invasiveness,suggesting that the recombinant S.typhimurium can be used as live vaccine vector for eliciting complete immunogenicity.The data may yield better understanding of the mechanism by which ice nucleation protein displays foreign proteins in the Salmonella strain.

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

    LENUS (Irish Health Repository)

    Hamilton, Shea

    2009-12-11

    Abstract 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

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

    Directory of Open Access Journals (Sweden)

    Cochrane Brett

    2009-12-01

    Full Text Available Abstract 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

  15. Intestinal invasion of Salmonella enterica serovar Typhimurium in the avian host is dose dependent and does not depend on motility and chemotaxis

    DEFF Research Database (Denmark)

    Olsen, John Elmerdahl; Hoegh-Andersen, Kirsten Hobolt; Rosenkrantz, Jesper Tjørnholt;

    2013-01-01

    Salmonella enterica serotype Typhimurium (S. Typhimurium) can invade in the intestine of the avian host, and knowledge on the mechanisms that govern this is potentially important for prevention of disease. This study investigated the invasion of S. Typhimurium in the avian host and to which extent...... functional flagella or chemotaxis genes. In support of the results from intestinal loop experiments, flagella and chemotaxis genes were not significantly important to the outcome of an oral infection. The results showed that S. Typhimurium invasion in the avian host was dose dependent and was not affected...

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

    Science.gov (United States)

    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 ...

  17. A Salmonella Typhimurium-Typhi genomic chimera: a model to study Vi polysaccharide capsule function in vivo.

    Directory of Open Access Journals (Sweden)

    Angela M Jansen

    2011-07-01

    Full Text Available The Vi capsular polysaccharide is a virulence-associated factor expressed by Salmonella enterica serotype Typhi but absent from virtually all other Salmonella serotypes. In order to study this determinant in vivo, we characterised a Vi-positive S. Typhimurium (C5.507 Vi(+, harbouring the Salmonella pathogenicity island (SPI-7, which encodes the Vi locus. S. Typhimurium C5.507 Vi(+ colonised and persisted in mice at similar levels compared to the parent strain, S. Typhimurium C5. However, the innate immune response to infection with C5.507 Vi(+ and SGB1, an isogenic derivative not expressing Vi, differed markedly. Infection with C5.507 Vi(+ resulted in a significant reduction in cellular trafficking of innate immune cells, including PMN and NK cells, compared to SGB1 Vi(- infected animals. C5.507 Vi(+ infection stimulated reduced numbers of TNF-α, MIP-2 and perforin producing cells compared to SGB1 Vi(-. The modulating effect associated with Vi was not observed in MyD88(-/- and was reduced in TLR4(-/- mice. The presence of the Vi capsule also correlated with induction of the anti-inflammatory cytokine IL-10 in vivo, a factor that impacted on chemotaxis and the activation of immune cells in vitro.

  18. The therapeutic potential of propolis against damage caused by Salmonella typhimurium in mice liver: A biochemical and histological study

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    Kalia Preeti

    2015-01-01

    Full Text Available Honeybee products are a rich source of nutritive supplements and traditional medication. The increasing resistance of bacteria towards various antibiotics and the limited scope of some vaccines makes it important to explore alternative therapies to combat bacterial diseases. The present study aimed to evaluate the antibacterial action of propolis using biochemical and histopathological methods in Salmonella typhimurium-infected BALB/c mice. Crude propolis was collected from an apiary and extracted with 70% ethanol. Hepatotoxicity was induced in mice by infecting them with Salmonella typhimurium (104 colony-forming units (CFU, and the hepatoprotective activity of propolis was evaluated by administration of different doses of propolis (100, 300 and 500 mg/kg body weight for 30 days. Biochemical and histopathological examinations were performed at regular intervals during the experimental period. Results obtained after treatment were compared with similar studies performed on normal control mice. Infected mice showed elevated liver marker enzymes and revealed the presence of characteristic typhoidal nodules in histological preparations. These results point to the therapeutic activity of propolis against Salmonella typhimurium.

  19. Immune response of turkey poults exposed at 1 day of age to either attenuated or wild Salmonella strains.

    Science.gov (United States)

    Hesse, Martina; Stamm, Andreas; Weber, Rita; Glünder, Gerhard; Berndt, Angela

    2016-06-01

    Salmonellosis is a foodborne zoonosis that is most often acquired by consuming poultry products such as eggs and poultry meat. Amongst other measures the vaccination of food-producing poultry is thought to contribute to a reduction in human salmonellosis. In the European Union (EU) in 2014 the licence of a commercially available Salmonella vaccine for chickens and ducks was extended to turkeys. In the present study, we examined the course of infection with a virulent Salmonella enterica ssp. enterica serovar Enteritidis (SE) strain, a virulent S. enterica ssp. enterica serovar Typhimurium (ST) strain, and the respective live vaccine containing attenuated strains of both serovars in turkey poults. Besides collecting microbiological data and detecting invading Salmonella in the caecal mucosa via immunohistochemistry, we also assessed immune reactions in terms of antibody production, influx of CD4-, CD8α- and CD28-positive cells into the caecal mucosa and the expression of four different immune-related proteins. We found that the attenuated strains were able to invade the caecum, but to a lower degree and for a shorter duration of time compared to virulent strains. Infections with virulent Salmonellae also caused an increase in CD4-, CD8α- and CD28-positive cells in the caecal mucosa and an increased transcription of iNOS, IL-8-like chemokines, and IFN-γ. In poults treated with attenuated bacteria we could not detect any evidence of immune responses. In conclusion, the vaccine showed a lower degree of caecal invasion and induced weaker immune reactions compared to the virulent Salmonella strains in turkeys. The efficiency of the vaccine has to be verified in future studies.

  20. Murein lipoprotein is a critical outer membrane component involved in Salmonella enterica serovar typhimurium systemic infection.

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    Fadl, A A; Sha, J; Klimpel, G R; Olano, J P; Niesel, D W; Chopra, A K

    2005-02-01

    Lipopolysaccharide (LPS) and Braun (murein) lipoprotein (Lpp) are major components of the outer membrane of gram-negative enteric bacteria that function as potent stimulators of inflammatory and immune responses. In a previous paper, we provided evidence that two functional copies of the lipoprotein gene (lppA and lppB) located on the chromosome of Salmonella enterica serovar Typhimurium contributed to bacterial virulence. In this study, we characterized lppA and lppB single-knockout (SKO) mutants and compared them with an lpp double-knockout (DKO) mutant using in vitro and in vivo models. Compared to the lpp DKO mutant, which was nonmotile, the motility of the lpp SKO mutants was significantly increased (73 to 77%), although the level of motility did not reach the level of wild-type (WT) S. enterica serovar Typhimurium. Likewise, the cytotoxicity was also significantly increased when T84 human intestinal epithelial cells and RAW264.7 murine macrophages were infected with the lpp SKO mutants compared to the cytotoxicity when cells were infected with the lpp DKO mutant. The level of interleukin-8 (IL-8) in polarized T84 cells infected with the lppB SKO mutant was significantly higher (two- to threefold higher), reaching the level in cells infected with WT S. enterica serovar Typhimurium, than the level in host cells infected with the lppA SKO mutant. The lpp DKO mutant induced minimal levels of IL-8. Similarly, sera from mice infected with the lppB SKO mutant contained 4.5- to 10-fold-higher levels of tumor necrosis factor-alpha and IL-6; the levels of these cytokines were 1.7- to 3.0-fold greater in the lppA SKO mutant-infected mice than in animals challenged with the lpp DKO mutant. The increased cytokine levels observed with the lppB SKO mutant in mice correlated with greater tissue damage in the livers and spleens of these mice than in the organs of animals infected with the lppA SKO and lpp DKO mutants. Moreover, the lppB SKO mutant-infected mice had increased

  1. Effects of P22 bacteriophage on salmonella Enterica subsp. enterica serovar Typhimurium DMC4 strain biofilm formation and eradication

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    Karaca Basar

    2015-01-01

    Full Text Available Over the last decades, several antimicrobial agents have been made available. Due to increasing antimicrobial resistance, bacteriophages were rediscovered for their potential applications against bacterial infections. In the present study, biofilm inhibition and eradication of Salmonella enterica subsp. enterica serovar Typhimurium DMC4 strain (S. Typhimurium was evaluated with respect to different incubation periods at different P22 phage titrations. The efficacy of P22 phage on biofilm formation and eradication of S. Typhimurium DMC4 strain was screened in vitro on polystyrene and stainless steel surfaces. The biofilm forming capacity of S. Typhimurium was significantly reduced at higher phage titrations (106 pfu/mL ≤. All phage titers (104-108 pfu/mL were found to be effective at the end of the 24 h-incubation period whereas higher phage titrations were found to be effective at the end of the 48 h and 72 h of incubation. P22 phage has less efficacy on already formed, especially mature biofilms (72 h-old biofilm. Notable results of P22 phage treatment on S. Typhimurium biofilm suggest that P22 phage has potential uses in food systems.

  2. Antimicrobial susceptibility and virulence characteristics of Salmonella enterica Typhimurium isolates from healthy and diseased pigs in Korea.

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    Tamang, Migma Dorji; Gurung, Mamata; Nam, Hyang-Mi; Moon, Dong Chan; Jang, Geum-Chan; Jung, Suk-Chan; Lim, Suk-Kyung

    2014-09-01

    This study compared the antimicrobial susceptibility and prevalence of virulence genes in Salmonella enterica Typhimurium isolated from healthy and diseased pigs in Korea. A total of 456 Salmonella Typhimurium isolated from healthy (n = 238) and diseased (n = 218) pigs between 1998 and 2011 were investigated. In total, 93.4% of the Salmonella Typhimurium isolates were resistant to at least one antimicrobial agent tested. The isolates were most often resistant to tetracycline (85.7%), followed by streptomycin (83.6%), nalidixic acid (67.3%), ampicillin (49.3%), chloramphenicol (42.8%), and gentamicin (37.1%). Moreover, multidrug resistance phenotype and resistance to ampicillin, florfenicol, gentamicin, nalidixic acid, neomycin, streptomycin, and tetracycline were significantly higher (P invA, spiA, msgA, sipB, prgH, spaN, tolC, lpfC, sifA, sitC, and sopB virulence genes. The prevalence of orgA, pagC, and iroN were 50.2, 74.1, and 91.0%, respectively, whereas isolates carrying cdtB (1.5%), pefA (7.0%), and spvB (14.9%) were identified much less frequently. Furthermore, the prevalence of invA, lpfC, orgA, pagC, and iroN was significantly higher (P < 0.01) among the isolates from the diseased pigs than in isolates from the healthy pigs. Our results demonstrated that, among diseased pigs, there was significantly higher resistance to some antimicrobials and greater prevalence of some virulence genes than in healthy pigs, indicating the role these factors play in pathogenesis. Multidrug-resistant Salmonella isolates that carry virulence-associated genes are potentially more dangerous and constitute a public health concern. Thus, continuous surveillance of antimicrobial resistance and virulence characteristics in Salmonella is essential.

  3. Ingestion of a novel galactoglucomannan oligosaccharide-arabinoxylan (GGMO-AX) complex affected growth performance and fermentative and immunological characteristics of broiler chicks challenged with Salmonella typhimurium.

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    Faber, T A; Dilger, R N; Iakiviak, M; Hopkins, A C; Price, N P; Fahey, G C

    2012-09-01

    Fermentable carbohydrates may enhance the ability of the gastrointestinal tract to defend against a pathogenic infection. We hypothesized that a galactoglucomannan oligosaccharide-arabinoxylan (GGMO-AX) complex would positively affect immune status and prevent colonization and shedding in Salmonella typhimurium-infected chicks. Using a completely randomized design, 1-d-old commercial broiler chicks (n = 240 chicks; 4 replications/treatment; 5 chicks/replication) were assigned to 1 of 6 dietary treatments differing in concentration of GGMO-AX (0, 1, 2, or 4%) or containing 2% Safmannan or 2% short-chain fructooligosaccharides. Cellulose was used to make diets iso-total dietary fiber. On d 10 posthatch, an equal number of chicks on each diet were inoculated with either phosphate-buffered saline (sham control) or Salmonella typhimurium (1 × 10(8) cfu). All birds were euthanized on d 10 postinoculation (PI) for collection of intestinal contents and select tissues. Body weight gain and feed intake of chicks were greater (P AX-fed chicks having the lowest. The GGMO-AX substrate demonstrated effects similar to a prebiotic substrate as indicated by increased cecal short-chain fatty acid concentrations, decreased cecal pH, and increased populations of Lactobacillus spp. and Bifidobacteria spp. as dietary GGMO-AX concentration increased. Excreta Salmonella typhimurium populations on d 5 and 10 PI, and ileal and cecal Salmonella typhimurium populations, tended to be affected (P AX had similar expressions of IFN-γ and IL-1β, regardless of infection, suggesting that Salmonella typhimurium virulence was suppressed. Dietary supplementation with GGMO-AX resulted in prebiotic-like effects but did not limit Salmonella typhimurium intestinal colonization or shedding, but possibly decreased the virulence of Salmonella typhimurium within the digestive tract.

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

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    Park, Mi-Kyung; Chin, Bryan A

    2016-12-28

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

  5. AKTIVITAS REACTIVE OXYGEN SPECIES MAKROFAG AKIBAT STIMULASI GEL LIDAH BUAYA PADA INFEKSI Salmonella typhimurium

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    R. Susanti

    2012-09-01

    Full Text Available Reactive Oxygen Species (ROS merupakan salah satu lethal chemical yang dapatmembunuh dan mengeliminasi bakteri pada sel fagosit. Lidah Buaya (Aloevera banyak dipakai sebagai pengobatan tradisional, tetapi belum ada buktiilmiah sampai tingkat seluler apalagi subseluler dalam hal efek imunostimulanpada penyakit infeksi. Tujuan penelitian ini adalah untuk mengetahui aktivitasimunostimulan dari gel lidah buaya yang ditunjukkan oleh aktivitas ROS makrofagsecara in vivo terhadap infeksi bakteri patogen Salmonella typhimurium. Sebanyak24 ekor mencit BABL/c betina umur 8-10 minggu berat 20-30 gram dikelompokkansecara acak menjadi empat kelompok, masing-masing kelompok enam ekor.Kelompok kontrol tidak diberi gel Aloe vera, sementara kelompok P1, P2, dan P3berturut-turut diberi gel Aloe vera 0,5 ml/ekor/hari; 1,0 ml/ekor/hari, dan 1,5ml/ekor/hari. Pemberian gel Aloe vera dilakukan selama sembilan hari. Pada harike-6, mencit diinfeksi bakteri patogen Salmonella typhimurium intraperitoneal105 CFU. Selanjutnya pada hari ke-10 mencit didislokasi dan dibedah, diambilmakrofag dari peritoneum untuk dianalisis produksi ROS-nya. Hasil penelitianmenunjukkan bahwa pemberian gel Aloe vera berpengaruh signi..ikan terhadappeningkatan produksi ROS makrofag mencit BALB/c yang diinfeksi Salmonellatyphimurium. Terdapat perbedaan secara signi..ikan antara kelompok kontroldengan kelompok P1, P2, dan P3, tetapi tidak terdapat perbedaan signi..ikan antarkelompok P1, P2, dan P3. Pemberian gel Aloe vera dosis 0,5 ml/ekor/hari sudahmampu meningkatkan produksi ROS makrofag. Reactive Oxygen Species (ROS is one of lethal chemicals that can kill and eliminatebacteria in phagocytic cells. Aloe vera is widely used as traditional medicine, but thereis no scienti..ic evidence to prove the effect of immunostimulatory of the Aloe vera gel oninfectious disease in the cellular or subcellular level. This research aims to determinethe immunostimulatory activity of Aloe vera gel showed by

  6. Radiosensitivity of E.coli O157: H7 and Salmonella typhimurium on swiss chard

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    Pereira, Marco A.S.; Mastro, Nelida L. del [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: masperei@ipen.br; nlmastro@ipen.br

    2007-07-01

    Swiss Chard is a beet (Beta vulgaris cicla) producing large yellowish green leaves with thick succulent stalks and often cooked as a potherb, called also seakale beet or chard. It is a nutritive vegetable rich in potassium, calcium, magnesium, sodium, phosphorus and vitamin C. Ionising radiation is an effective method to reduce pathogens. Radiation sensitivity of bacteria, however, depends on several factors. Particularly, few data are available on the ability of low-dose ionizing radiation to inactivate pathogenic bacteria on ready to eat vegetables. The aim of this study was the evaluation of the radiation sensitivity of pathogens experimentally contaminating the mentioned vegetable. Swiss chard leaves minimally processed were inoculated separately either with E. coli O157:H7 or Salmonella typhimurium by immersion to contain 6 log CFU/g and 1h later gamma-irradiated with 0.25 kGy, 0.5 kGy, 1 kGy and 1.5 kGy, dose rate of 2.94 kGy/h. The assay of pathogen survivors was made by direct plating. After applying a radiation dose of 0.5 kGy reductions of at least 3 log were achieved for both bacteria. The average D10 values, the radiation dose needed to inactivate 1 log of pathogen were 0.12 and 0.10 for E.coli O157:H7 and S.typhimurium respectively. These results indicate that irradiation may be an effective means for inactivating common foodborne pathogens that can eventually contaminate ready to eat vegetables. (author)

  7. Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum.

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    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

  8. Colonization of a marker and field strain of Salmonella enteritidis and a marker strain of Salmonella typhimurium in vancomycin-pretreated and nonpretreated laying hens.

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    Hannah, J F; Wilson, J L; Cox, N A; Richardson, L J; Cason, J A; Bourassa, D V; Buhr, R J

    2011-12-01

    This study was conducted to evaluate the influence of a vancomycin pretreatment on the ability of marker (nalidixic-acid resistant) Salmonella Enteritidis (SE(M)), field Salmonella Enteritidis (SE(E)), and marker Salmonella Typhimurium (ST(M)) strains to colonize within the intestinal and reproductive tracts and translocate to other organs of leghorn laying hens. In each of three trials, caged laying hens (76, 26, and 33 wk ofage) were divided into six groups designated to receive SE(M), SE(F), or ST(M), and half were pretreated with vancomycin (n = 11-12 hens). Vancomycin-treated hens received 10 mg vancomycin in saline/kilogram body weight orally for 5 days to inhibit Gram-positive bacteria within the intestines. On Day 6, all hens were concurrently challenged by oral, intravaginal, and intracolonal routes with Salmonella and placed into separate floor chambers by Salmonella strain. Two weeks postinoculation, all hens were euthanatized and the ceca, spleen, liver/gall bladder (LGB), upper (URT), and lower (LRT) reproductive tracts, and ovarian follicles were aseptically collected, and analyzed for Salmonella. Results did not differ for the three hen's ages and were therefore combined. The vancomycin pretreatment also had no significant effect on the colonization ability of SE(M), SE(F) or ST(M), and therefore results were combined within Salmonella strain. The marker strain of Salmonella Enteritidis was recovered from 21% of ceca, 4% of LGB, 9% of LRT, and 17% of the fecal samples. The field strain of Salmonella Enteritidis was recovered from 88% of ceca, 96% of spleen, 92% of LGB, 30% of LRT, 4% of URT, 13% of follicle, and 42% of the fecal samples. The marker strain of Salmonella Typhimurium was recovered from 100% of ceca, 74% of spleen, 91% of LGB, 30% of LRT, 9% of URT, 9% of follicle, and 100% of the fecal samples. Among ceca, spleen, LGB, and fecal samples, SE(F) and ST(M) colonization was significantly greater than SE(M) colonization. Overall prevalence

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

    Science.gov (United States)

    Van Parys, Alexander; Boyen, Filip; Verbrugghe, Elin; Leyman, Bregje; Bram, Flahou; Haesebrouck, Freddy; Pasmans, Frank

    2012-06-13

    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.

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

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    Van Parys Alexander

    2012-06-01

    Full Text Available Abstract 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.

  11. Tigecycline challenge triggers sRNA production in Salmonella enterica serovar Typhimurium

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    Yu Jing

    2012-09-01

    Full Text Available Abstract Background Bacteria employ complex transcriptional networks involving multiple genes in response to stress, which is not limited to gene and protein networks but now includes small RNAs (sRNAs. These regulatory RNA molecules are increasingly shown to be able to initiate regulatory cascades and modulate the expression of multiple genes that are involved in or required for survival under environmental challenge. Despite mounting evidence for the importance of sRNAs in stress response, their role upon antibiotic exposure remains unknown. In this study, we sought to determine firstly, whether differential expression of sRNAs occurs upon antibiotic exposure and secondly, whether these sRNAs could be attributed to microbial tolerance to antibiotics. Results A small scale sRNA cloning strategy of Salmonella enterica serovar Typhimurium SL1344 challenged with half the minimal inhibitory concentration of tigecycline identified four sRNAs (sYJ5, sYJ20, sYJ75 and sYJ118 which were reproducibly upregulated in the presence of either tigecycline or tetracycline. The coding sequences of the four sRNAs were found to be conserved across a number of species. Genome analysis found that sYJ5 and sYJ118 mapped between the 16S and 23S rRNA encoding genes. sYJ20 (also known as SroA is encoded upstream of the tbpAyabKyabJ operon and is classed as a riboswitch, whilst its role in antibiotic stress-response appears independent of its riboswitch function. sYJ75 is encoded between genes that are involved in enterobactin transport and metabolism. Additionally we find that the genetic deletion of sYJ20 rendered a reduced viability phenotype in the presence of tigecycline, which was recovered when complemented. The upregulation of some of these sRNAs were also observed when S. Typhimurium was challenged by ampicillin (sYJ5, 75 and 118; or when Klebsiella pneumoniae was challenged by tigecycline (sYJ20 and 118. Conclusions Small RNAs are overexpressed as a result of

  12. Characterization and differential gene expression between two phenotypic phase variants in Salmonella enterica serovar Typhimurium.

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    Sheila K Patterson

    Full Text Available 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

  13. Effect of inducible nitric oxide synthase binding with peroxisomes on early infection of macrophages by Salmonella typhimurium

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    Xin PAN

    2011-10-01

    Full Text Available Objective To investigation on the early carrying inducible nitric oxide synthase for peroxisomes to Salmonella typhimurium during the bacteria infection mouse macrophages.Methods RAW264.7 macrophages were transfected with pTassC-GFP plasmids to analysis the existence form of green fluorescent protein labeled target for Salmonella secreted protein SpiC(TassCprotein in the cell.The interaction between the fusion protein TassC-GFP and peroxisomes were analyzed by co-transfection of pTassC-GFP and pDsRed2-Perxi(labels peroxisomes red plasmids to RAW264.7 macrophages,the positive transfected cells named RAW-DT.RAW-D cells were named by transfecting RAW264.7 with pDsRed2-Perxi plasmids.S.typhimurium was detected with mono-antibody and visualized with Alexa Fluor 350 conjugated donkey anti-mouse antibodies.Inducible nitric oxide synthase(iNOS or NOS2 was detected with iNOS-antibody and visualized with Alexa Fluor 488 conjugated goat anti-rabbit antibodies.S.typhimurium were used to infect the RAW-DT cells to analyze the interaction among bacteria,TassC-GFPs and peroxisomes.The RAW-D cells were infected with S.typhimurium 1h to analyze the interaction among bacteria,iNOS and peroxisomes.Results TassC vesicles co-localized with peroxisomes when RAW264.7 macrophages were co-transfected with pTassC-GFP and pDsRed2-Perxi plasmids.It was determined by a three-dimensional(xyz fluorescence microscopy that the recruitment or overlapping of TassC-GFP and pemxiomes to the Salmonella-containing vacuoles(SCV after infection of RAW-DT macrophages with S.typhimurium for 1h.The SCVs also could co-localized with peroxisomes and iNOS after infection of RAW-D cells with S.typhimurium for 1h.Upon entry of Salmonella,peroxisomes were recruited to the Salmonella-containing vesicles and remain aggregated around the SCV for the duration of the 60 minutes observation time.Conclusion These findings indicated that,wild type S.typhimurium could induce iNOS production in RAW264

  14. Isolation of Salmonella enterica subsp. enterica (O:4,5:i and Salmonella enterica subsp. Typhimurium from free-living domestic pigeons (Columba livia

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    R.C. Rocha-e-Silva

    2014-10-01

    Full Text Available The present study reports the isolation of Salmonella enterica in organs of free-living domestic pigeons. In the clinic examination, the presence of feces in the peri-cloacal and abdominal regions were observed, as well as symptoms such as cachexy, incoordination and opisthotonos. Before any therapeutic protocol was applied the bird died and a necropsy was then performed for the removal of spleen, liver, kidney and intestine for bacteriological examination and antibiotic sensitivity test. Salmonella enterica subsp.enterica (O:4,5:i- and Salmonella enterica subsp. enterica serovar Typhimurium were isolated from the liver and intestine and the sensitivity test demonstrated that these strains are sensitive to several antibiotics.

  15. A multiplex real-time PCR assay for the identification and differentiation of Salmonella enterica serovar Typhimurium and monophasic serovar 4,[5],12:i:-.

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    Prendergast, Deirdre M; Hand, Darren; Nί Ghallchóir, Eadaoin; McCabe, Evonne; Fanning, Seamus; Griffin, Margaret; Egan, John; Gutierrez, Montserrat

    2013-08-16

    Salmonella enterica subsp. enterica serovar 4,[5],12:i:- is considered to be a monophasic variant of Salmonella Typhimurium and is increasingly associated with human infections. The use of PCR for the unequivocal identification of strains identified by conventional serotyping as 4,[5],12:i:- has been recommended by the European Food Safety Authority (EFSA), in particular the conventional multiplex PCR developed by Tennant et al. (2010). An alternative protocol for the identification and differentiation of S. Typhimurium and S. Typhimurium-like strains, including its monophasic variants, based on a multiplex real-time PCR assay was developed in our laboratory. A panel of 206 Salmonella strains was used to validate our multiplex real-time PCR against the conventional multiplex PCR recommended by EFSA, i.e. 43 Salmonella strains of serovars other than Typhimurium and 163 routine isolates determined by slide agglutination serotyping to have an incomplete antigenic formula compatible with the S. Typhimurium formula 4,[5],12:i:1,2. Both methods correctly identified the 43 Salmonella strains as non S. Typhimurium. Among the 163 isolates of undetermined serovar by conventional serotyping, both PCR protocols identified 54 isolates as S. Typhimurium, 101 as monophasic S. Typhimurium and 8 as non-S. Typhimurium. Twenty isolates phenotypically lacking the phase-2 H antigen were positive for the fljB.1,2 gene. These strains have been recently described in the literature by other workers and have been referred to as "inconsistent" variants of S. Typhimurium. Antimicrobial resistance and phage typing were also performed on the S. Typhimurium isolates, including monophasic variants, and approximately half of the isolates identified as monophasic S. Typhimurium by our multiplex real-time PCR protocol were DT193 with the resistance pattern ASSuT. There was 100% concordance between the conventional PCR and the multiplex real-time PCR method developed in this study which proved that

  16. RGD Peptide Cell-Surface Display Enhances the Targeting and Therapeutic Efficacy of Attenuated Salmonella-mediated Cancer Therapy.

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    Park, Seung-Hwan; Zheng, Jin Hai; Nguyen, Vu Hong; Jiang, Sheng-Nan; Kim, Dong-Yeon; Szardenings, Michael; Min, Jung Hyun; Hong, Yeongjin; Choy, Hyon E; Min, Jung-Joon

    2016-01-01

    Bacteria-based anticancer therapies aim to overcome the limitations of current cancer therapy by actively targeting and efficiently removing cancer. To achieve this goal, new approaches that target and maintain bacterial drugs at sufficient concentrations during the therapeutic window are essential. Here, we examined the tumor tropism of attenuated Salmonella typhimurium displaying the RGD peptide sequence (ACDCRGDCFCG) on the external loop of outer membrane protein A (OmpA). RGD-displaying Salmonella strongly bound to cancer cells overexpressing αvβ3, but weakly bound to αvβ3-negative cancer cells, suggesting the feasibility of displaying a preferential homing peptide on the bacterial surface. In vivo studies revealed that RGD-displaying Salmonellae showed strong targeting efficiency, resulting in the regression in αvβ3-overexpressing cancer xenografts, and prolonged survival of mouse models of human breast cancer (MDA-MB-231) and human melanoma (MDA-MB-435). Thus, surface engineering of Salmonellae to display RGD peptides increases both their targeting efficiency and therapeutic effect.

  17. Haloarchaeal gas vesicle nanoparticles displaying Salmonella SopB antigen reduce bacterial burden when administered with live attenuated bacteria.

    Science.gov (United States)

    DasSarma, Priya; Negi, Vidya Devi; Balakrishnan, Arjun; Karan, Ram; Barnes, Susan; Ekulona, Folasade; Chakravortty, Dipshikha; DasSarma, Shiladitya

    2014-07-31

    Innovative vaccines against typhoid and other Salmonella diseases that are safe, effective, and inexpensive are urgently needed. In order to address this need, buoyant, self-adjuvating gas vesicle nanoparticles (GVNPs) from the halophilic archaeon Halobacterium sp. NRC-1 were bioengineered to display the highly conserved Salmonella enterica antigen SopB, a secreted inosine phosphate effector protein injected by pathogenic bacteria during infection into the host cell. Two highly conserved sopB gene segments near the 3'-coding region, named sopB4 and B5, were each fused to the gvpC gene, and resulting GVNPs were purified by centrifugally accelerated flotation. Display of SopB4 and B5 antigenic epitopes on GVNPs was established by Western blotting analysis using antisera raised against short synthetic peptides of SopB. Immunostimulatory activities of the SopB4 and B5 nanoparticles were tested by intraperitoneal administration of recombinant GVNPs to BALB/c mice which had been immunized with S. enterica serovar Typhimurium 14028 ΔpmrG-HM-D (DV-STM-07), a live attenuated vaccine strain. Proinflammatory cytokines IFN-γ, IL-2, and IL-9 were significantly induced in mice boosted with SopB5-GVNPs, consistent with a robust Th1 response. After challenge with virulent S. enterica serovar Typhimurium 14028, bacterial burden was found to be diminished in spleen of mice boosted with SopB4-GVNPs and absent or significantly diminished in liver, mesenteric lymph node, and spleen of mice boosted with SopB5-GVNPs, indicating that the C-terminal portions of SopB displayed on GVNPs elicit a protective response to Salmonella infection in mice. SopB antigen-GVNPs were found to be stable at elevated temperatures for extended periods without refrigeration in Halobacterium cells. The results all together show that bioengineered GVNPs are likely to represent a valuable platform for the development of improved vaccines against Salmonella diseases.

  18. Avaliação clínica da infecção experimental de bezerros com Salmonella Typhimurium

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    L.G. Ávila

    2011-12-01

    Full Text Available The clinical conditions of healthy calves infected with 10(9 CFU of Salmonella Typhimurium were evaluated and the viability of the experimental model in disease induction was verified. Twelve male Holstein calves, 10 to 15-days old, were examined. They were allocated into two groups, control and experimentally infected. Animals were submitted to clinical examination after inoculation and at every 24 hours, during six days after infection. Samples of rectal swabs were collected for Salmonella Typhimurium isolation. Results showed that all animals had different degrees of diarrhea, with mucus and bleeding, 24 to 72 hours after experimental infection with Salmonella Typhimurium, accompanied by fever, but no signs of sepsis. The isolation of Salmonella Typhimurium from rectal swabs occurred 24 hours after the infection and there were no deaths during the experiment, which means that this sorovar has an epidemiological importance related to the intermitent or continuous elimination of the bacterium. Results also showed that the oral administration of 10(9 CFU of Salmonella Typhimurium induces clinical signs of salmonellosis in 10 to 15-day-old calves.

  19. Influence of temperature and predation on survival of Salmonella enterica serovar Typhimurium and expression of invA in soil and manure-amended soil.

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    García, R; Baelum, J; Fredslund, L; Santorum, P; Jacobsen, C S

    2010-08-01

    The effects of three temperatures (5, 15, and 25 degrees C) on the survival of Salmonella enterica serovar Typhimurium in topsoil were investigated in small microcosms by three different techniques: plate counting, invA gene quantification, and invA mRNA quantification. Differences in survival were related to the effect of protozoan predation. Tetracycline-resistant Salmonella serovar Typhimurium was inoculated into soil and manure-amended soil at 1.5 x 10(8) cells g soil(-1). Population densities were determined by plate counting and by molecular methods and monitored for 42 days. Simultaneous extraction of RNA and DNA, followed by quantitative PCR, was used to investigate invA gene levels and expression. Analysis by these three techniques showed that Salmonella serovar Typhimurium survived better at 5 degrees C. Comparing DNA and CFU levels, significantly higher values were determined by DNA-based techniques. invA mRNA levels showed a fast decrease in activity, with no detectable mRNA after an incubation period of less than 4 days in any of the soil scenarios. A negative correlation was found between Salmonella serovar Typhimurium CFU levels and protozoan most probable numbers, and we propose the role of the predator-prey interaction as a factor to explain the die-off of the introduced strain by both culture- and DNA quantification-based methods. The results indicate that temperature, manure, and protozoan predation are important factors influencing the survival of Salmonella serovar Typhimurium in soil.

  20. Application of the Random Forest method to analyse epidemiological and phenotypic characteristics of Salmonella 4,[5],12:i:- and Salmonella Typhimurium strains.

    Science.gov (United States)

    Barco, L; Mancin, M; Ruffa, M; Saccardin, C; Minorello, C; Zavagnin, P; Lettini, A A; Olsen, J E; Ricci, A

    2012-11-01

    Salmonella enterica 4,[5],12:i:- is a monophasic variant of S. Typhimurium. In the last decade, its prevalence rose sharply. Although S. 4,[5],12:i:- and S. Typhimurium are known to pose a considerable public health risk, there is no detailed information on the circulation of these serovars in Italy, particularly as far as veterinary isolates are concerned. For this reason, a data set of 877 strains isolated in the north-east of Italy from foodstuffs, animals and environment was analysed during 2005-2010. The Random Forests (RF) method was used to identify the most important epidemiological and phenotypic variables to show the difference between the two serovars. Both descriptive analysis and RF revealed that S. 4,[5],12:i:- is less heterogeneous than S. Typhimurium. RF highlighted that phage type was the most important variable to differentiate the two serovars. The most common phage types identified for S. 4,[5],12:i:- were DT20a, U311 and DT193. The same phage types were also found in S. Typhimurium isolates, although with a much lower prevalence. DT7 and DT120 were ascribed to the two serovars at comparable levels. DT104, DT2 and DT99 were ascribed exclusively to S. Typhimurium, and almost all the other phage types identified were more related to the latter serovar. Such data confirm that phage typing can provide an indication of the biphasic or monophasic state of the strains investigated and could therefore support serotyping results. However, phage typing cannot be used as the definitive method to differentiate the two serovars, as part of the phage types were detected for both serovars and, in particular, all phage types found for S. 4,[5],12:i- were found also for S. Typhimurium.

  1. Isolation and validation of an endogenous fluorescent nucleoid reporter in Salmonella Typhimurium.

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    Ioannis Passaris

    Full Text Available In this study we adapted a Mud-based delivery system to construct a random yfp reporter gene (encoding the yellow fluorescent protein insertion library in the genome of Salmonella Typhimurium LT2, and used fluorescence activated cell sorting and fluorescence microscopy to screen for translational fusions that were able to clearly and specifically label the bacterial nucleoid. Two such fusions were obtained, corresponding to a translational yfp insertion in iscR and iolR, respectively. Both fusions were further validated, and the IscR::YFP fluorescent nucleoid reporter together with time-lapse fluorescence microscopy was subsequently used to monitor nucleoid dynamics in response to the filamentation imposed by growth of LT2 at high hydrostatic pressure (40-45 MPa. As such, we were able to reveal that upon decompression the apparently entangled LT2 chromosomes in filamentous cells rapidly and efficiently segregate, after which septation of the filament occurs. In the course of the latter process, however, cells with a "trilobed" nucleoid were regularly observed, indicative for an imbalance between septum formation and chromosome segregation.

  2. Antioxidant oils and Salmonella enterica Typhimurium reduce tumor in an experimental model of hepatic metastasis

    Directory of Open Access Journals (Sweden)

    Sorenson BS

    2011-05-01

    Full Text Available Brent S Sorenson, Kaysie L Banton, Lance B Augustin, Arnold S Leonard, Daniel A SaltzmanDepartment of Surgery, University of Minnesota Medical School, Minneapolis, MN, USAAbstract: Fruit seeds high in antioxidants have been shown to have anticancer properties and enhance host protection against microbial infection. Recently we showed that a single oral dose of Salmonella enterica serovar Typhimurium expressing a truncated human interleukin-2 gene (SalpIL2 is avirulent, immunogenic, and reduces hepatic metastases through increased natural killer cell populations in mice. To determine whether antioxidant compounds enhance the antitumor effect seen in SalpIL2-treated animals, we assayed black cumin (BC, black raspberry (BR, and milk thistle (MT seed oils for the ability to reduce experimental hepatic metastases in mice. In animals without tumor, BC and BR oil diets altered the kinetics of the splenic lymphocyte response to SalpIL2. Consistent with previous reports, BR and BC seed oils demonstrated independent antitumor properties and moderate adjuvant potential with SalpIL2. MT oil, however, inhibited the efficacy of SalpIL2 in our model. Based on these data, we conclude that a diet high in antioxidant oils promoted a more robust immune response to SalpIL2, thus enhancing its antitumor efficacy.Keywords: antioxidants, colorectal cancer, tumor models, metastasis

  3. Testing of some azo dyes and their reduction products for mutagenicity using Salmonella typhimurium TA 1538.

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    Garner, R C; Nutman, C A

    1977-07-01

    A series of ten azo dyes as well as various single ring aromatic amines substituted on the benzene ring were tested for bacterial mutagenicity with Salmonella typhimurium TA 1538 using a soft-agar overlay method. Two dyes, sudan 2 and chrysoidin induced mutation but only in the presence of a rat liver preparation. Chrysoidin was the more active. Testing of its reduction products, aniline and 1,2,4-triaminobenzene showed a liver metabolite of the latter compound could be responsible for the mutagenic effect, having a comparable mutagenicity with 1,2-diamino-4-nitro-benzene, one of the mutagenic constituents of hair dyes. Structure-activity studies on a series of ring-substituted anilines indicated that mutagenic activity required at least two positions to be substituted with either amino or nitro groups, or one of each. The bacteria as well as the liver enzyme preparation may partake in the activation of these chemicals. The correlation between mutagenicity and carcinogenicity for this group of compounds is discussed.

  4. A Salmonella Typhimurium mutant strain capable of RNAi delivery: higher tumor-targeting and lower toxicity.

    Science.gov (United States)

    Cheng, Xiawei; Zhang, Xiaoxin; Zhou, Yuqiang; Zhang, Chunmei; Hua, Zi-Chun

    2014-08-01

    Bacteria are highly versatile and useful tools that could deliver short interfering RNA. In this study, a phoP/phoQ double-deleted Salmonella Typhimurium named VNP(PhoP/Q(-)) based on the genetic background of VNP20009. The biological safety and function of VNP(PhoP/Q(-)) were also analyzed. Our study revealed the following results: (1) VNP(PhoP/Q(-)) exhibited lower titers in tumor-free livers and spleens than VNP20009, (2) The survival of VNP(PhoP/Q(-)) in macrophages and 4T1 tumor cells was significantly reduced compared with that of VNP20009, (3) The tumor-targeting ability of VNP(PhoP/Q(-)) was significantly enhanced compared with that of VNP20009, and the anticancer effects of VNP(pPhoP/Q(-)) and VNP20009 on tumor-bearing mice were similar, (4) VNP(PhoP/Q(-)) could release an shRNA-expressing plasmid and express the EGFP reporter gene in tumor tissue. Therefore, VNP(PhoP/Q(-)) exhibited a better safety level in tumor-free mice and elicited an anti-tumor effect on tumor-bearing mice. Moreover, VNP(PhoP/Q(-)) could release an shRNA-expressing plasmid into the cytoplasm of host cells to silence targeted genes.

  5. Bottlenecks and Hubs in Inferred Networks Are Important for Virulence in Salmonella typhimurium

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    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.

  6. Bottlenecks and hubs in inferred networks are important for virulence in Salmonella typhimurium.

    Science.gov (United States)

    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, 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, examining cellular response to environmental conditions and effects of 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 and hub genes were identified from these inferred networks, and we show for the first time that these genes are significantly more likely to be essential for virulence than their non-bottleneck or non-hub counterparts. Networks generated using simple similarity metrics (correlation and mutual information) 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.

  7. Antibacterial Effects of Pyrolysis Oil Against Salmonella Typhimurium and Escherichia coli.

    Science.gov (United States)

    Patra, Jayanta Kumar; Das, Gitishree; Choi, Joon Weon; Baek, Kwang-Hyun

    2016-01-01

    Many issues have been found to be related to food preservation and food contamination caused by various pathogenic bacteria in recent years. Many antibacterial agents act efficiently against Gram-positive foodborne bacteria; however, they are less effective against Gram-negative foodborne bacteria. In the present study, an attempt has been made to evaluate the antibacterial activity of pyrolysis oil manufactured from Pinus densiflora (PLO) against two Gram-negative foodborne pathogenic bacteria, Salmonella Typhimurium and Escherichia coli O157:H7. PLO possessed potent antibacterial activity against both foodborne pathogenic bacteria, as indicated by inhibition zones of 10.33-12.33 mm and minimum inhibitory concentration and minimum bactericidal concentration values of 250-500 μg/mL and 500-1000 μg/mL, respectively. PLO at the minimum inhibitory concentration exhibited an inhibitory effect on the viability of the bacterial pathogens with leakage of 260 nm absorbing materials, an increase in the relative electrical conductivit