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PubMed1997

Homologous regions of the Salmonella enteritidis virulence plasmid and the chromosome of Salmonella typhi encode thiol: disulphide oxidoreductases belonging to the DsbA thioredoxin family.

The nucleotide sequence relatedness between the chromosome of Salmonella typhi and the virulence plasmid of Salmonella enteritidis was investigated using short DNA probes of < 2 kb covering the whole virulence plasmid sequence. Only one homologous region was detected. This region was subsequently cloned and partially sequenced. Sequences closely related to the pefl gene and the ORFs orf7, orf8 and orf9, which are located downstream of the fimbrial pef operon of the Salmonella typhimurium virulence plasmid, were detected. Sequencing of the cloned S. typhi DNA fragment also revealed identity with genes of the fimbrial sef operon characterized in the chromosome of S. enteritidis. These nucleotide sequences mapped upstream of the S. typhi chromosomal region homologous to the S. enteritidis virulence plasmid. The general organization of the cloned S. typhi chromosomal fragment was similar to the fimbriae-encoding region of the S. typhimurium virulence plasmid. The deduced product of orf8 in the S. typhimurium virulence plasmid, as well as those of the corresponding ORFs in the homologous region of the S. typhi chromosome and in the S. enteritidis virulence plasmid (designated dlt and dlp, respectively), appeared to be related to the thioredoxin family of thiol: disulphide oxidoreductases. The dlp gene was able to complement the DTT-sensitive phenotype, the inability to metabolize glucose 1-phosphate and the low alkaline phosphatase activity of a dsbA mutant of Escherichia coli. The dlt gene partially complemented the lack of alkaline phosphatase activity, but not the other mutant phenotypes. The products of both genes could be detected using the T7 RNA polymerase promoter expression system. The estimated molecular masses of the products of the dlt and dlp genes by SDS-PAGE were 26 and 23 kDa, respectively, the first being in agreement with the deduced amino acid sequence and the latter, somewhat smaller. The processing of a possible leader peptide in the Dlp protein, but not in the Dlt protein, could be responsible for this difference. The Dlp protein appeared as a doublet band on SDS-PAGE, which is characteristic of the oxidized and reduced states of this kind of protein.

Amino Acid Sequence↗

PubMed1995

Salmonella typhimurium and Salmonella enteritidis induce gut growth and increase the polyamine content of the rat small intestine in vivo.

The effects of infection by Salmonella enteritidis and S. typhimurium on the small and large intestines, liver, spleen and mesenteric nodules of rats were studied in vivo. Both Salmonella serotypes persisted and proliferated in the gastrointestinal tract and invaded sub-epithelial tissues, mainly the ileum, leading to the systemic distribution of these pathogens. Coincidental with infection, the rate of crypt cell proliferation increased resulting in substantial growth of the small intestine. The extent of this and the accompanying accumulation of polyamines was particularly dramatic in the ileum where there was also some disruption of the villus epithelium. It is possible that these effects of the infection on the metabolism and morphology of the small bowel, which strongly resembled the changes induced by some plant lectins, may facilitate the colonisation and invasion of the gut by Salmonellae.

Animals↗

PubMed2003

Induction of antimicrobial pathways during early-phase immune response to Salmonella spp. in murine macrophages: gamma interferon (IFN-gamma) and upregulation of IFN-gamma receptor alpha expression are required for NADPH phagocytic oxidase gp91-stimulated oxidative burst and control of virulent Salmonella spp.

The effect of gamma interferon (IFN-gamma) on elevation of reactive oxygen species and the viability of virulent wild-type and avirulent mutants of Salmonella enterica serovar Typhimurium and S. enterica serovar Infantis was studied in a murine macrophage cell line (J774.2 cells). S. enterica serovar Typhimurium 14028 phoP and a rough lipopolysaccharide mutant of S. enterica serovar Infantis 1326/28 (phi(r)) (avirulent mutants) induced NADPH phagocytic oxidase gp91 (gp91(phox)) activity and a significant (P < 0.05) elevation of reactive oxygen species within 12 h without coculture with IFN-gamma. This coincided with reduced survival of S. enterica serovar Typhimurium14028 phoP or stasis of S. enterica serovar Infantis phi(r). Fluorometric studies indicated that expression of IFN-gamma on infected J774.2 cells was not significantly (P > 0.05) elevated. However, studies with the virulent S. enterica serovar Typhimurium strains showed that a comparable level of control of bacterial numbers could only be achieved by coculture with IFN-gamma. This coincided with significant upregulation of IFN-gamma receptor alpha expression on the surface of J774.2 cells and was completely abolished by N-acetyl-L-cysteine captopril (an inhibitor of reactive oxygen species). Delay in reactive oxygen species induction due to a requirement for IFN-gamma and upregulation of IFN-gamma receptor alpha in macrophages infected with virulent salmonellae may result in greater dissemination of virulent salmonellae in host tissue.

Animals↗

PubMed1971

Serological relationships of Salmonella A bacteriophages isolated from salmonellae in different Kauffmann-White groups.

Six different Salmonella group A phages from salmonellae in Kauffmann- White groups B, C(1), C(2), and D were examined serologically. Those phages which were specific for a particular somatic antigen were found to be serologically very similar. Antiserum against a phage with one specificity was able to neutralize a different phage with the same specificity but unable to neutralize, in the normal way, a phage with a different specificity. Phages mixed with heterologous phage antiserum responded with an "inhibition response" in which there appeared to be a neutralization of the phage infectivity for the first 10 min, followed by a reversal of the neutralization until, by 20 or 25 min, there was no apparent neutralization. This response was interpreted to indicate that the adsorption antigens, probably situated on the tail fibers, were different for phages with different specificities but sufficiently similar so that heterologous antibodies could react with the antigens; but the antigen-antibody complex was quickly disassociated, resulting in a modification of the antibody molecules but no change in the specificity sites of the antigen. A subgrouping of the Salmonella A phages based on their antigenic specificity is suggested.

Animals↗

PubMed2002

Induction of CD8+ T lymphocytes by Salmonella typhimurium is independent of Salmonella pathogenicity island 1-mediated host cell death.

Salmonella are intracellular bacterial pathogens that reside and replicate inside macrophages, and attenuated strains of Salmonella typhimurium can be used to deliver heterologous Ags for MHC class I and/or MHC class II-restricted presentation. Recently, it was shown that invasion of macrophages by S. typhimurium may result in the death of host macrophages via a mechanism harboring features of apoptotic and necrotic cell death. However, it is unknown whether this bacterial-induced host cell death affects immunity. In addition, it has been hypothesized that macrophage death following infection with S. typhimurium and subsequent uptake of apoptotic cells by APC are fundamental to the induction of CTL responses. In this study we investigated the in vivo induction of Ag-specific CD8+ T lymphocyte responses and compared CD8+ T lymphocyte responses elicited with S. typhimurium strains carrying a mutation in their invA gene, and therefore an inability to induce Salmonella pathogenicity island 1 (SPI-1)-mediated macrophage death, with responses elicited by an attenuated deltaaroAD strain. Ag-specific CD8+ T lymphocyte responses were analyzed using IFN-gamma ELISPOT, tetramer binding, and in vivo and in vitro CTL assays. Our results showed that deltaaroAD and deltaaroADdeltainvA induced comparable levels of Ag-specific CD8+ T lymphocyte responses as well as protective, Ag-specific B and CD4+ T lymphocyte immunity. Furthermore, experiments in macrophage-depleted mice showed that CD8+ T lymphocyte responses were effectively induced in the absence of macrophages. Together, our results imply that in this infection model, SPI-1-mediated cell death does not affect the immunological defense response and is not important for the induction of CD8+ T lymphocyte responses.

Administration, Oral↗

PubMed2001

Multidrug-resistant Salmonella typhimurium and Salmonella enteritidis identified by multiplex PCR from animals.

Antibiotic resistance in Salmonella enteritidis and S. typhimurium, one of most frequent etiologic pathogens of food-borne bacterial gastroenteritidis in humans, is a serious health problem worldwide. Fifteen and 22 each of S. enteritidis and S. typhimurium were isolated from animals from 1983 to 1999 in Korea and tested for their antibiotic resistance patterns and phage types. S. enteritides isolates were highly resistant to sulfonamides (86.7%) and four of them (26.6%) showed multiple antibiotic resistance. The most frequent phage type (PT) of S. enteritids was PT1 (33.3%) even though none of them had multiple antibiotic resistance. S. typhimurium isolates were highly resistant to streptomycin, sulfonamides, and tetracycline, 100%, 95.5%, and 86.4% respectively. The incidence of multiple antibiotic resistance of S. typhimurium isolates was extremely high (100%) comparing to S. enteritidis isolates (26.7%). Two of the five ACSSuT type S. typhimurium isolates, resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline, were phage type DT104. All S. typhimurium isolates were sensitive to florfenicol. For the rapid detection of multiple antibiotic resistant S. enteritidis and S. typhimurium isolates, particularly ACSSuT type S. typhimurium DT104, antibiotic resistance genes, cmlA/tetR, PSE-1, and TEM, and Salmonella spp. Specific gene, SipB/C, were amplified using four pairs of primers in hot-started multiplex polymerase chain reaction. Two Korean isolates of S. typhimurium DT104 showed TEM amplicons instead of PSE-1 for the ampicillin resistance. The multiplex PCR used in this study was useful in rapid detection of ACSSuT type S. typhimurium and identification of b-lactamase gene distribution among Salmonella isolates.

Animals↗

PubMed1992

[Epidemiology of salmonella infections in Algeria. Evolution of the salmonella serovars isolated from 1986 to 1990].

The serovars evolution of 3340 Salmonella strains isolated from 1986 to 1990 in Algeria have been studied. Among Salmonella responsible for typhoid-paratyphoid fevers, 98% are S. typhi; the prevalence of this serovar is observed every year. Among the other Salmonella, 50 different serovars have been isolated from 1986 to 1990. The predominant serovars change every year but 98% out of the total belong to 8 groups of Kauffmann White scheme; the most frequent are: groups O: 6, 7-O: 8-O: 4 and O: 9.

Algeria↗

PubMed2004

Dramatic shift in the epidemiology of Salmonella enterica serotype Enteritidis phage types in western Europe, 1998-2003--results from the Enter-net international salmonella database.

Salmonella enterica serotype Enteritidis is the predominant salmonella serovar identified by the Enter-net national reference laboratories in western Europe. As it is the most commonly recognised serotype, it is important that phage typing is carried out so that outbreaks can be recognised and confirmed, and trends in infections identified. Data from the Enter-net salmonella database show that there has been a dramatic shift between phage types identified in Europe from 1998-2003. In 1998, the proportion of phage type (PT) 4 was 61.8%, making it the most frequently identified phage type in humans (21,630 cases), whereas by 2003 the proportion of PT4 had fallen to 32.1% (8794 cases) with other strains increasing, both in proportion and numbers. This paper identifies the emerging strains that are becoming more relevant in public health terms.

Animals↗

PubMed1992

Comparison of Hektoen and Salmonella-Shigella agar on 6033 stools of human origin submitted for routine isolation of Salmonella sp. and Shigella sp.

From 1989 through 1991, 6033 stool specimens from patients at Orleans Hospital (France), were cultured for enteric pathogens. Hektoen agar (HE) was compared with Salmonella-Shigella agar (SS) after direct streaking and after overnight enrichment in Mueller-Kauffmann broth. Yersinia strains were not computed. Seven strains of Salmonella serotype Typhi were isolated, on both media, and excluded from computations for discussed reasons. Out of a total of 9 Shigella strains, HE isolated 9 and SS isolated 7. No statistically significant difference appeared about isolation of non-Typhi Salmonella strains (127 vs 114 from direct streaking, 237 vs 243 after enrichment). Predictive values of suspicious colonies were not statistically different. Numbers of false positives were not different, except for black centred colonies of the direct streaking (231 on HE vs 186 on SS, p less than 0.05). The skill of technologists was not taken into account but was found likely to be more accurate on SS agar. This data suggest that, since the frequency of Shigella sp became much lower, the differential of efficiency of HE vs SS agar is no longer obvious in human medical routine.

Agar↗

PubMedDate not supplied

Epidemiological aspects of Salmonella infantis and Salmonella typhi murium infections in Finnish broiler chickens.

In this paper salmonella infections in Finnish broilers have been described. Especially infections detected in the farms of company A have been studied. Attention has been paid to the year by year continuing numerous S. infantis infections. In agreement with earlier reports, there is some evidence suggesting that a hatchery might have spread the infections. The examination of grandparent and parent birds as well as hatcheries with respect to salmonella infections should be more thorough and clear. It is, for example, for the moment not known at the farms of company A from which parent bird flocks the chickens come. This knowledge should be very important when the origin of salmonella infections is tried to be clarified.

Animals↗

PubMed1993

Virulence of Salmonella enteritidis phagetypes 4, 8 and 13 and other Salmonella spp. for day-old chicks, hens and mice.

Virulence of three Canadian poultry strains of Salmonella enteritidis, namely phagetypes (PT) 4, 8 and 13, and one Salmonella heidelberg strain was assessed in orally and intraperitoneally inoculated one-day old chickens and compared to the virulence of a human S. enteritidis PT 4 strain from the United Kingdom (UK). The two PT 4 strains were also compared in orally inoculated adult laying hens. In addition, orally inoculated Balb/c mice were used to evaluate virulence of the above strains and two strains of Salmonella typhimurium containing different plasmids. In orally inoculated one-day old chickens, the UK S. enteritidis PT 4 strain was more virulent than the Canadian PT 4 strain. The UK PT 4 strain was also more virulent and invasive in adult laying hens than the Canadian PT 4 strain. The S. enteritidis PT 8 strain and one S. typhimurium strain isolated from a chicken hatchery were the most virulent for orally inoculated Balb/c mice. This strain of S. typhimurium contained the 60 megadalton plasmid associated with virulence for Balb/c mice which was not present in the S. typhimurium strain isolated from a pig with septicemic disease.

Animals↗

PubMed2002

Isolation of spectinomycin resistance mutations in the 16S rRNA of Salmonella enterica serovar Typhimurium and expression in Escherichia coli and Salmonella.

Two single-base mutations in 16S rRNA conferring high-level resistance to spectinomycin were isolated on a plasmid-borne copy of the rrnD operon from Salmonella enterica serovar Typhimurium. Neither of the mutations (C1066U and C1192U) had appreciable effects on cell growth, but each had differential effects on resistance to spectinomycin and fusidic acid. Both mutations also conferred resistance to spectinomycin in Escherichia coli strains containing deletions of all seven chromosomal rrn operons and expressing plasmid-encoded Salmonella rRNA exclusively. In contrast, when expressed in E. coli strains containing intact chromosomal rrn operons, the strains were sensitive to spectinomycin. However, chromosomal mutations arose that allowed expression of the rRNA-dependent spectinomycin resistance phenotype. It is proposed that in heterogeneous rRNA populations, the native E. coli rRNA out-competes the heterologous Salmonella rRNA for binding to ribosomal proteins, translation factors, or ribosome assembly, thus limiting entry of the antibiotic-resistant 30S subunits into the functioning ribosome pool.

Anti-Bacterial Agents↗

PubMed1983

Cytotonic enterotoxins and cytotoxic factors produced by Salmonella enteritidis and Salmonella typhimurium.

Strains of Salmonella enteritidis and Salmonella typhimurium isolated from human diarrheal cases produced heat-labile enterotoxin(s) and cytotoxic factor(s) which elongated, lysed or deformed Chinese hamster ovary cells in tissue culture. The toxin(s) caused fluid accumulation in ligated rabbit gut loops and produced increased skin permeability. Salmonella toxin produced by these strains does not cross-react immunologically with high titer Vibrio cholerae toxin antisera or heat-labile Escherichia coli enterotoxin antisera used in this study and does not bind to galactose--Sepharose gel. The activity of the toxin was not inhibited by GM1-ganglioside.

Animals↗

PubMed1996

Characterisation of monoclonal antibodies specific to SEF 21 fimbriae of Salmonella enteritidis and their reactivity with other Salmonellae and Enterobacteria.

A panel of monoclonal antibodies (mAbs) specific to type 1 (SEF 2) fimbriae of S. enteritidis was produced using crude and HPLC purified preparations of SEF 21 fimbriae. Sixteen mAbs were selected by indirect ELISA using both purified SEF 21 antigen and whole cells of S. enteritidis. Eight mAbs were confirmed by immunoprecipitation assay to react specifically with SEF 21 fimbriae. These mAbs were further characterised for their reactivity patterns by the "whole cell" ELISA and latex agglutination test with a number of strains of Salmonella and other enterobacteria. Not all SEF 21 mAbs reacted in both ELISA and latex agglutination tests with whole bacterial cells. mAb 611 was the only one suitable for use in both tests. Unexpectedly these mAbs reacted with the type 1 fimbriae of many of the tested strains of enterobacteria. mAb 721 reacted with most strains of Salmonella (89.1%) and enterobacteria (71.4%) tested. mAb 611 reacted with 61%-75% of strains of Salmonella and with 6.9%-17.6% of enterobacteria in ELISA and latex tests respectively. These mAbs will be useful reagents for further characterisation of type 1 fimbriae expressed by members of the family Enterobacteriaceae.

Animals↗

PubMed1999

Salmonella level of Danish swine herds based on serological examination of meat-juice samples and Salmonella occurrence measured by bacteriological follow-up.

Analyses of data collected in the Danish Salmonella Control Program in swine herds were conducted to assess the association between bacteriological and serological findings (including the degree to which changing serological status over time modulated the relationship) and to assess the degree to which type of swine operation and age group affected the relationship between bacteriological and serological findings. Although serological status was significantly associated with bacteriological prevalence of salmonella enterica in swine herds, the association was clarified by adding information on the change in serological status over time and the age group being tested. Salmonella infection assessed by serological tests at a single time-point and data on age group tested would allow better targeting and managing control programs.

Animals↗

PubMed1985

Proteins from Salmonella R-mutants mediating protection against Salmonella typhimurium infection in mice. III. Separation and purification of soluble proteins and their use as vaccines and as precipitating antigens.

Urea extracts of Salmonella-S-form and R-mutant bacteria were separated into water-soluble and water-insoluble fractions and analysed with respect to their chemical composition. The main portion of proteins which at the same time represented the majority of the different polypeptides, was found in the water soluble fraction. This fraction, in the case of R-mutants, exhibited a considerably lower contamination with LPS and phospholipid than the total urea extract. This facilitated the further purification of proteins which could thus be carried out in urea-free buffer systems. In mice infected with S. typhimurium, the water soluble fraction afforded protection to the same extent as the total urea extract. The purified soluble proteins of Salmonella-R-mutants exhibited protective activity to injection with S. typhimurium and S. heidelberg comparable to that seen with the soluble extract. A species overlapping character of the protection became evident. In the Ouchterlony gel precipitation test, using the water soluble fraction and purified proteins as antigens, antibodies could be detected in rabbit immune sera and in sera of patients with Salmonella infections.

Animals↗

PubMedDate not supplied

Molecular relationships between virulence plasmids of Salmonella serotypes typhimurium and dublin and large plasmids of other Salmonella serotypes.

All studied isolates of Salmonella serotypes abortusovis (16 strains), enteritidis (30 strains), paratyphi C (29 strains), and 2 out of 10 isolates of serotype newport harboured large 54-76-Kb plasmids. No such plasmids were found in the following serotypes: agona, bovismorbificans, heidelberg, infantis, panama, paratyphi A, paratyphi B, saintpaul, senftenberg and typhi. These plasmids and the virulence-associated plasmids of Salmonella serotypes typhimurium and dublin were compared at the molecular level. Plasmids from the same serotype usually showed similar HindIII endonuclease patterns. Plasmids from different serotypes displayed markedly different cleavage patterns. Using the 3H-labelled plasmid from serotype typhimurium strain C5 as a probe, nitrocellulose filter hybridization showed that all these plasmids shared homologous sequences distributed throughout the plasmid molecule. With the S1-nuclease method, all plasmids were 61 to 88% related to the virulence plasmid of serotype typhimurium strain C5. The large plasmids in Salmonella serotypes abortusovis, enteritidis, paratyphi C, newport and the virulence-associated plasmids in serotypes typhimurium and dublin thus constitute a single group of homology and represent a family of related plasmids. We suggest that this plasmid group may contribute to the pathogenic potential of host serotypes.

DNA↗

PubMed1984

The effect of feeding diets containing avoparcin on the excretion of salmonellas by chickens experimentally infected with natural sources of salmonella organisms.

Chickens were readily infected with salmonella organisms when fed diets containing unsterilized bone-meal or provided with drinking water containing a suspension of natural salmonella infected chicken faeces. When fed diets containing avoparcin at concentrations of 10 or 100 mg/kg chickens infected in these ways excreted larger numbers of salmonellas for longer periods than did chickens fed a nonmedicated diet.

Animal Feed↗