Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SALMONELLA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2004

Characterization of Salmonella pathogenicity island 1 type III secretion-dependent hemolytic activity in Salmonella enterica serovar Typhimurium.

A number of bacteria that are pathogenic for animals and plants possess a type III secretion system (TTSS) to translocate virulence-associated proteins into host cells. In several bacteria, it has been reported that the TTSS is correlated with an ability to cause contact-dependent hemolysis in vitro. Here, we showed that the Salmonella enterica serovar Typhimurium strain SL1344 exhibited Salmonella pathogenicity island 1 type III secretion-dependent, contact-mediated, hemolytic activity. Mutations with a single deletion in genes encoding putative pore-forming proteins, SipB and SipC, secreted by the TTSS abolished hemolytic activity. In addition, the osmoprotection studies revealed that molecules larger than PEG2000 conferred significant protection against lysis induced by Salmonella. These results indicate that the hemolysis generated by Salmonella is due to the formation of pores within the erythrocyte membrane.

Bacterial Proteins↗
PubMed1997

A comparison of procedures involving single step Salmonella, 1-2 Test, and modified semisolid Rappaport-Vassiliadis medium for detection of Salmonella in ground beef.

Procedures involving Single Step Salmonella (SSS), 1-2 Test, and Modified Semisolid Rappaport-Vassiliadis Medium (MSRV) were compared for their speed and sensitivity in detection of Salmonella in ground beef contaminated with one isolate of each of five Salmonella serotypes. Inocula of 10, 10(2) and 10(3) CFU/g of ground beef were used. When pre-enrichment in buffered peptone water and selective enrichment in tetrathionate broth were used, SSS and MSRV detected all five species of Salmonella at all levels of contamination, whereas the 1-2 Test was positive in 0, 12, and 15 of 15 tests at 10, 10(2) and 10(3) CFU/g, respectively. When only pre-enrichment was used, the results with MSRV were unchanged but the SSS test failed to detect S. typhimurium. Thus, with pre-enrichment the MSRV and SSS procedures were equally sensitive and both produced a result on the third day. The 1-2 Test was less sensitive and slower, with results available on day-4. The MSRV protocol was best overall.

Animals↗
PubMed1998

Characterisation of epitopes of type 1 fimbriae of Salmonella using monoclonal antibodies specific for SEF21 fimbriae of Salmonella enteritidis.

Monoclonal antibodies (mAbs) were used to identify and characterise epitopes of type 1 (SEF21) fimbriae of Salmonella enteritidis. The distribution of the epitopes among salmonellas and other enterobacteria was investigated, as well as the influence of growth media and temperatures on their expression. At least four different epitope clusters were identified on SEF21 fimbriae of S. enteritidis. Two of these clusters were associated with fimbrial haemagglutinins that were either common to all salmonellae tested, or restricted only to S. enteritidis and S. dublin. The four epitope clusters were identified on type 1 fimbriae of most Salmonella serotypes, as well as non-haemagglutinating type 2 fimbriae of S. pullorum and S. gallinarum, and on many other enterobacterial species. The expression of the epitopes was affected by growth conditions.

Animals↗
PubMed1997

Screening for Salmonella with a murine monoclonal antibody M105 detects both Felix O1 bacteriophage sensitive and resistant Salmonella strains.

Ten Felix O1 (FO1) bacteriophage sensitive Salmonella strains as well as their phage resistant derivates together with 39 strains of FO1-resistant Salmonella were tested for their reactivities with a murine monoclonal antibody, M105, by indirect whole cell and competitive ELISA. All FO1 phage sensitive and 48 of the 49 FO1-resistant Salmonella strains were found to react with M105. The single Salmonella strain not reacting with M105 was a FO1 resistant derivative selected by exposing the sensitive parent strain to the phage. This M105-negative and FO1-resistant strain was also found to be a rough mutant without O-antigens and possibly lacks the terminal LPS core sugars which form the M105 reactive epitope.

Antibodies, Bacterial↗
PubMed1994

Polymerase chain reaction for Salmonella virulence-associated plasmid genes detection: a new tool in Salmonella epidemiology.

The important role of plasmid genes in assessing virulence for BALB/c mice in salmonella, and the difficulty of using standard techniques to detect them, led us to develop a detection method by gene amplification. One hundred and forty-three strains (71 serovars) of salmonella and 35 strains of other species were tested using specific oligonucleotide primers. The amplification products were identified by a specific oligonucleotide probe. Forty-nine salmonella strains from ten serovars (S. abortus ovis, S. choleraesuis, S. dublin, S. enteritidis, S. gallinarum/pullorum, S. hessarek, S. typhimurium, S. IIIa 48:z4, z23, S. IV 43:z4, z23:-, S. V 28:a:-) produced a positive and specific response. Because of various origins of the strains possessing the gene sought and the diversity of the responses, both from one serovar to another and in the same serovar, this search has its place among the epidemiological markers in general use. This method appears well suited to the research and detection of plasmid genes associated with mouse virulence in salmonella.

Animals↗
PubMed1998

Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium phage-type DT104 among salmonellae causing enteritis in Israel.

The relative frequency of salmonella strains isolated from hospitalized and non-hospitalized patients in Southern Israel changed during the period, 1994-6. Salmonella enterica serotype Typhimurium definitive phage-type 104 (DT104) appeared in Israel in 1994 and became the most prevalent strain in 1996. An outbreak of enteritis due to Salmonella enterica serotype Agona occurred in Israel, in October 1994 and lasted for 4 months. The relative frequency of Salmonella enterica serotype Enteritidis remained almost constant during these years, with seasonal fluctuations only. The importance of the increase in the prevalence of Typhimurium DT104 has been the epidemic spread of a multiresistant strain of R-type ACT (A, ampicillin; C, chloramphenicol; T, tetracycline) belonging to this phage-type. Since 1995 the frequency of Typhimurium DT104 isolates that possess, in addition to the above R-type, a chromosomally encoded resistance to the quinolone drug, nalidixic acid, increased tenfold. In 1996, 27% of the Typhimurium DT104 isolates were of R-type ACTN. S. Enteritidis exhibited over 95% susceptibility to at least eight of the most commonly used antibiotic drugs, and none of the isolates was resistant to quinolone or fluoroquinoline.

Bacteriophage Typing↗
PubMed2001

Characterization of Salmonella-induced filaments (Sifs) reveals a delayed interaction between Salmonella-containing vacuoles and late endocytic compartments.

Salmonella typhimurium is a facultative intracellular pathogen that colonizes host cells throughout the course of infection. A unique feature of this pathogen is its ability to enter into (invade) epithelial cells and elongate the vacuole within which it resides into tubular structures called Salmonella-induced filaments (Sifs). In this study we sought to characterize the mechanism of Sif formation by immunofluorescence analysis using subcellular markers. The late endosomal lipid lysobisphosphatidic acid associated in a punctate pattern with the Salmonella-containing vacuole, starting 90 min after infection and increasing thereafter. Lysobisphosphatidic acid-rich vesicles were also found to interact with Sifs, at numerous sites along the tubules. Similarly, cholesterol-rich vesicles were also found in association with intracellular bacteria and Sifs. The lysosomal hydrolase cathepsin D was present in Sifs, both in a punctate pattern and, at later times, predominantly in an uninterrupted linear pattern. Rab7 associated with Sifs and expression of the N125I dominant negative mutant of this GTPase inhibited Sif formation. Transfection of HeLa cells with a vector encoding SifA fused to the green fluorescent protein caused swelling and aggregation of lysobisphosphatidic acid-containing compartments, suggesting that this virulence factor directs membrane fusion events involving late endosomes. Our findings demonstrate that Sif formation involves fusion of late endocytic compartments with the Salmonella-containing vacuole, and suggest that SifA modulates this event.

Animals↗
PubMed1965

The immunochemistry of Salmonella chemotype VI O-antigens. The structure of oligosaccharides from Salmonella group G (o 13,22) lipopolysaccharides.

1. Lipopolysaccharides have been isolated from ;smooth' (S) strains of Salmonella friedenau and Salmonella poona by the phenol-water method and purified in the preparative ultracentrifuge. 2. These lipopolysaccharides are serologically indistinguishable and on partial acid hydrolysis the same series of oligosaccharides was obtained in each instance. 3. The results of quantitative micro-analysis, borohydride reduction, periodate oxidation, Morgan-Elson reactions and enzymic hydrolysis with beta-galactosidase on the isolated oligosaccharides indicate that the O-specific side chains of these lipopolysaccharides have a repeating pentasaccharide unit that is beta-d-galactosyl-(1-->3)-N-acetylgalactosaminyl-(1-->3)-N-acetylgalactosaminyl-(1-->4)-l-fucose with a d-glucose residue bound at an undetermined point on this structure. 4. Two oligosaccharides, a glucosyl-galactose and an N-acetylglucosaminylglucose, have also been isolated and these seem to be identical with oligosaccharides obtained from ;rough' (R) Salmonella lipopolysaccharides. These findings are in accordance with the view that Salmonella S-lipopolysaccharides have a core that consists of R-lipopolysaccharide.

Antigens↗
PubMed1965

The immunochemistry of Salmonella chemotype VI O-antigens. The structure of oligosaccharides from Salmonella group N (o 30) lipopolysaccharides.

1. The lipopolysaccharides isolated from ;smooth' (S) strains of Salmonella godesberg and Salmonella urbana by the phenol-water method were purified in the ultracentrifuge. 2. These lipopolysaccharides have the same O-antigenic structure and on partial hydrolysis the same series of oligosaccharides was obtained in each instance. 3. The results of quantitative microanalysis, borohydride reduction, periodate oxidation, Morgan-Elson reactions and enzymic hydrolysis with alpha- and beta-glucosidases on the isolated oligosaccharides indicated that the O-specific side chains of these S-lipopolysaccharides have a repeating tetrasaccharide unit that is beta-d-glucosyl-(1-->3)-N-acetylgalactosaminyl-(1-->4)-l-fucose with a further glucose residue bound at the 4-position on the N-acetylgalactosamine. 4. Another oligosaccharide, a glucosylgalactose, has also been isolated and is indistinguishable from an oligosaccharide isolated from Salmonella R-lipopolysaccharides. These findings provide further evidence supporting the view that all Salmonella S-lipopolysaccharides have a core consisting of R-lipopolysaccharide.

Antigens↗
PubMed2000

Improvement in Salmonella detection in milk and dairy products: comparison between the ISO method and the Oxoid SPRINT Salmonella test.

The Oxoid SPRINT Salmonella test was compared with the ISO method (ISO 6579: 1993) for the detection of Salmonella in milk and dairy products. Samples were artificially contaminated, in some cases with sublethally injured salmonellas. Experiments with raw milk, soft cheese made from heat-treated milk (mould-ripened and with smear) and soft cheese with smear made from raw milk showed no significant differences between the SPRINT and ISO methods. With dried milk products and mould-ripened soft cheese made from raw milk the reference method gave significantly more positive results. The addition of ferrioxamine E to pre-enrichment (ISO) or pre-enrichment/enrichment broth (SPRINT test) did not improve Salmonella detection.

Culture Media↗
PubMed2001

Detection of Salmonella and simultaneous detection of Salmonella and Shiga-like toxin-producing Escherichia coli using the magnetic capture hybridization polymerase chain reaction.

The magnetic capture hybridization polymerase chain reaction (MCH-PCR) was used to detect Salmonella and also to simultaneously detect Salmonella and Shiga-like toxin-producing Escherichia coli (SLTEC). Fifty-seven Salmonella and 41 SLTEC were included in the study. Salmonella were detected either individually by a single MCH-PCR assay targeting the inv gene or simultaneously with SLTEC by a multiplex MCH-PCR in which SLTEC were detected using primers for the slt genes. Both single and multiplex assays were found to be specific for tested pathogens. The results indicate that MCH-PCR can be used as means of detecting single or multiple bacterial pathogen(s).

Adhesins, Bacterial↗
PubMed1996

The use of a rapid Salmonella latex serogrouping test (Spectate) to assist in the confirmation of ELISA-based rapid Salmonella screening tests.

Spectate, a 10 min, simple, latex-based agglutination test for serogrouping of salmonellae, has been investigated as a tool to assist in the confirmation of ELISA presumptive positive broth samples when screening for salmonellae in foods. When obtaining a combined ELISA and Spectate positive result, there was a 90% (27/30) confidence limit of a genuine positive result, some one or two working days quicker than the traditional methods. Of the 10% (3/30) that were not confirmed as salmonellas, two gave a Spectate result which is advised as being a possible Citrobacter spp. and one sample gave a positive confirmation by Spectate only, which suggested a failure of the traditional confirmation process, a finding confirmed at other sites. Extensive studies performed at several food company microbiology laboratories showed Spectate to be a useful additional tool in the confirmation process of ELISA screening techniques for salmonellae in food. Additionally the concept of a "false positive' may need to be refined to that of a "not culturally' positive, given the apparent possible failure of the traditional confirmation methods.

Enzyme-Linked Immunosorbent Assay↗
PubMed1994

The sialic acid-containing lipopolysaccharides of Salmonella djakarta and Salmonella isaszeg (serogroup O: 48): chemical characterization and reactivity with a sialic acid-binding lectin from Cepaea hortensis.

Lipopolysaccharides (LPS) of Salmonella djakarta and Salmonella isaszeg, as well as of a spontaneous R-mutant of S. djakarta were investigated as to their content in neuraminic acid (Neu) and its individual linkage. The two Salmonella serovars both belong to the O:48 serogroup of Salmonella, but to two different subgroups. LPS of both S-forms contained high amounts of Neu, although in different quantities, whereas the R-form was completely devoid of it. Methylation analysis indicated that Neu is exclusively terminally linked in S. djakarta whereas both terminal and 4-linked Neu were recognized in S. isaszeg. Although terminally linked, a sialidase from Arthrobacter ureafaciens was unable to split Neu even after prolonged incubation from both S-type LPSs. When LPS was first treated by mild alkali, however, the total amount of Neu from S. djakarta LPS and about 50% from that of LPS of S.isaszeg could be removed. In contrast, alkali-treated LPS, but also the non-treated one, proved to be effective inhibitors for a sialic acid-binding lectin from Cepaea hortensis. The resistance of terminal Neu towards sialidase may be due to the presence of an O-acetyl group which would be removed during the methylation analysis but would, especially when linked to C-4, not interfere with the reactivity of the lectin.

Animals↗
PubMed1961

Isolation of Salmonellae from food samples. V. Determination of the method of choice for enumeration of Salmonella.

Comparison of three methods by which salmonellae may be isolated and enumerated from dried albumen, direct inoculation of enrichment media, centrifugation of samples, and pre-enrichment in noninhibitory media, reveals pre-enrichment to be the method of choice. The superiority of pre-enrichment manifests itself in replicate aliquots of the same sample by producing a statistically significant increase in numbers of isolations of salmonellae and in empirical use with various albumen samples by consistently higher values of most probable numbers (MPN). The primary factor involved in this superiority appears to be the greater ability of small numbers of salmonellae to initiate growth in the nonselective mannitol purple sugar broth than in the inhibitory enrichment media. The method of analysis recommended entails inoculation of mannitol broth pre-enrichment medium, transfer of 24-hr culture aliquots to tetrathionate broth, and streaking on brilliant green agar for isolation of salmonellae.

Agar↗
PubMed1981

Artificial Salmonella vaccines: Salmonella typhimurium O-antigen-specific oligosaccharide-protein conjugates elicit opsonizing antibodies that enhance phagocytosis.

Outbred NMRI mice and rabbits were vaccinated with different artificial Salmonella typhimurium immunogens and the specificity and activity of elicited antibodies were studied in in vivo and in vitro phagocytosis assays. The Salmonella immunogens used were: (i) the synthetic disaccharide, abequose (formula see text) D-mannose, representative of Salmonella O antigen 4, covalently linked to bovine serum albumin (BSA); (ii) the octa- and dodecasaccharides, (formula see text) covalently linked to BSA; and (iii) whole heat-killed Salmonella. Rabbit antibodies passively administered to mice significantly enhanced the clearance of intravenously injected S. typhimurium challenge bacteria from the bloodstream. The clearance rate and the titer of anti-O-antigen-specific antibodies correlated. The clearance rate of an S. thompson (O6,7) strain, which has a different O antigen, was the same irrespective of the rabbit serum given. NMRI mice actively immunized with the various oligosaccharide-BSA conjugates had a significantly increased clearance rate of S. typhimurium only. In the in vitro assay, mouse antioligosaccharide-BSA sera promoted phagocytosis of S. typhimurium, but not S. thompson, when incubated with complement and mouse peritoneal exudate cells activated with Freund complete adjuvant.

Animals↗
PubMed1993

The Salmonella typhimurium virulence plasmid increases the growth rate of salmonellae in mice.

The virulence plasmids of Salmonella typhimurium and other invasive Salmonella serovars have long been associated with the ability of these bacteria to cause systemic infection beyond the intestines in orally inoculated animals. Genetic analysis of virulence genes on the high-molecular-weight plasmids has revealed that no more than five genes spanning a 6.2-kb region are sufficient to replace the entire plasmid for conferring virulence. However, the exact virulence function(s) encoded by these genes has not been elucidated. In this report, we measured the possible effect of the virulence plasmid on the growth rate of S. typhimurium in mice by two complementary procedures. The first procedure used segregation of a temperature-sensitive plasmid in vivo to provide a measure of bacterial divisions and the number of recovered marker plasmid-containing salmonellae as a measure of killing. In the second procedure, aroA deletions were transduced into virulence plasmid-containing and plasmid-cured S. typhimurium. Since AroA- salmonellae are inhibited for growth in vivo, if the virulence plasmid affected only growth rate, no difference in the recoveries of the paired AroA- strains would be seen. Virulence plasmid-containing S. typhimurium segregated the marker plasmid more rapidly than did the virulence plasmid-cured strain, and AroA- derivatives of both strains were recovered equally from mice. Therefore, the S. typhimurium virulence plasmid increased growth rate but had no detectable effect on killing or bacterial movement into deep tissues. To examine whether the plasmid accomplished this function by affecting the intracellular/extracellular location of bacteria, orally infected mice were injected with gentamicin to kill the extracellular bacteria. Wild-type and plasmid-cured S. typhimurium strains were equally resistant to gentamicin in vivo and hence most likely located intracellularly to equal degrees. When wild-type and plasmid-cured S. typhimurium strains were sequestered within peritoneal chambers in mice, the resulting extracellular growth was equal. Therefore, the virulence plasmid increases the growth rate of S. typhimurium in mice, probably within mouse cells.

Animals↗
PubMed1999

Prior immunity to homologous and heterologous Salmonella serotypes suppresses local and systemic anti-fragment C antibody responses and protection from tetanus toxin in mice immunized with Salmonella strains expressing fragment C.

We have investigated the effect of preexisting immunity to homologous (Salmonella typhimurium) or heterologous (S. dublin) serotypes of Salmonella on the ability of an attenuated S. typhimurium aroA aroD vector (BRD509) to immunize mice against the heterologous antigen fragment C (FrgC). We studied two strains, BRD847 and BRD937, expressing FrgC carried on plasmids that differ only with respect to the promoter controlling FrgC expression, the nirB promoter in the case of BRD847 and the htrA promoter in the case of BRD937. Mice were preimmunized orally with S. typhimurium BRD509, S. dublin aroA aroD (BRD620), or saline. Forty-four days later, they were immunized orally with BRD847 or BRD937. Prior immunity to S. typhimurium severely depressed the serum immunoglobulin G (IgG) and IgA anti-FrgC response in both BRD847- and BRD937-immunized mice. Mice with existing immunity to S. dublin also had lower IgG anti-FrgC geometric mean titers (GMTs) than did mice preimmunized with saline, but this difference was significant only in the case of mice immunized with BRD937. However, in nonimmune mice or in mice preimmunized with S. typhimurium or S. dublin, the anti-FrgC IgG GMTs were always higher in mice in the BRD937 groups than in the equivalent BRD847 groups. This is reflected in the effect of prior immunity on the ability of oral immunization with BRD847 or BRD937 to protect mice from challenge with a lethal dose of tetanus toxin. All of the mice preimmunized with saline and then immunized with BRD847 or BRD937 survived challenge. Only 20% of the animals immunized with BRD847 and 60% of the mice in the BRD937 group survived tetanus toxin challenge if they were preimmunized with BRD509. Preexisting immunity to S. dublin did not affect the ability of BRD937 to immunize mice against tetanus, but it did reduce the efficiency of BRD847: only 60% percent of the mice survived challenge. The intestinal secretory IgA responses to FrgC were very similar in the BRD847 and BRD937 groups. Prior immunity did depress the IgA anti-FrgC titers but only significantly so in the mice preimmunized with BRD509. These results show that preexisting Salmonella immunity, particularly to homologous serotypes, can severely compromise the ability of live Salmonella vectors to deliver heterologous antigens to the mammalian immune system. However, the results also indicate that this may be overcome by the design of more powerful in vivo expression systems.

Animals↗
PubMed1992

Evaluation of two colored latex kits, the Wellcolex Colour Salmonella Test and the Wellcolex Colour Shigella Test, for serological grouping of Salmonella and Shigella species.

Two colored latex kits (the Wellcolex Colour Salmonella Test [WCT-Salmonella] and the Wellcolex Colour Shigella Test [WCT-Shigella]; Division Diagnostics, Laboratories Wellcome S.A., Paris, France), which allow identification of the most frequently encountered Salmonella serogroups and Shigella species, respectively, were evaluated. WCT-Salmonella and WCT-Shigella yielded sensitivities of 98.4 and 98%, respectively, and a specificity of 100% when they were tested on pure cultures received at a reference laboratory.

Evaluation Studies as Topic↗