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PubMed2001

[Salmonella infections in swine. Salmonella infections in swine in meat hygiene].

Salmonella is considered one of the most important food borne pathogens that has potential implications for human health. In Germany, Salmonella monitoring is being used in swine farms as a predictor for Salmonella infection and to implement control measures directed to minimise cross-contamination at the slaughter plant. An research project was established in order to gain experience with the eradication of Salmonella in German swine herds.

Abattoirs↗

PubMed1992

A multistate outbreak of Salmonella javiana and Salmonella oranienburg infections due to consumption of contaminated cheese.

OBJECTIVE: To determine the source of an outbreak of Salmonella javiana and Salmonella oranienburg infections. DESIGN: Laboratory-based statewide surveillance for Salmonella infections and two separate case-control studies. SETTING: Community- and industry-based studies conducted from May through October 1989. PARTICIPANTS: Thirty-one culture-confirmed outbreak-associated cases of S javiana infection and 60 community controls matched for telephone prefix, gender, and age in case-control study I; 50 cases, 100 community controls, and 64 family member controls in case-control study II. RESULTS: One hundred thirty-six culture-confirmed cases of S javiana infection and 11 cases of S oranienburg infection were associated with the outbreak in Minnesota. Outbreak-associated cases were also identified in Wisconsin (15 cases), and in Michigan and New York (one case each). Cases were more likely than controls to have consumed mozzarella cheese manufactured at a single cheese plant (plant X) or cheese that had been shredded at processing plants that also shredded cheese manufactured at plant X (odds ratio [OR], 7.2; 95% confidence interval [CI], 1.7 to 23.2; P < .01). The outbreak-associated strains of both serovars were isolated from two unopened 16-oz (0.45-kg) blocks of mozzarella cheese produced at plant X. The most probable numbers of Salmonella organisms in these samples were 0.36/100 g and 4.3/100 g. CONCLUSIONS: The potential for bacterial pathogen contamination of cheese during manufacture and processing has important epidemiologic implications, particularly because cheese consumption has recently increased in the United States. Low-level contamination of a nationally distributed food product can cause geographically dispersed foodborne outbreaks that may be difficult to detect.

Adolescent↗

PubMed1990

[Pilot study of the practicability of a commercially-available Salmonella rapid test for the detection of the Salmonella content of cattle fecal samples].

100 faeces samples of cattle were investigated in comparison to a recent commercially available Salmonella Rapid Test (OXOID) and a cultural standard method (non-selective enrichment in buffered peptone water, selective enrichment in RAPPAPORT-VASSILIADIS-medium) for presence of Salmonella. The Salmonella Rapid Test showed in positive results an accuracy ("sensitivity") of 94.7% and in negative results an assurance ("specificity") of 97.5% and is therefore suitable for rapid detection (within 2 days) of faeces sample of cattle with Salmonella.

Animals↗

PubMed1989

Prevalence of Salmonella serotypes in pigs and evaluation of a rapid, presumptive test for detection of Salmonella in pig faeces.

Two hundred faecal samples, collected from pigs at a Budapest abattoir, were examined for the presence of salmonellae. Ninety-six isolates, belonging to 7 different serotypes, were obtained. Salmonella derby (70.8%) was the most prevalent serotype. The other serotypes isolated were S. typhimurium (8.33%), S. bredeney (4.16%), S. agona (2.08%), S. infantis (9.22%), S. london (3.12%), and S. panama (2.08%). A modified rapid presumptive test to detect salmonellae in food and food ingredients was described by Hoben et al. (1973). This test medium was evaluated to determine its efficacy in detecting salmonellae in pig faecal samples. The test gave an efficiency of 88.67%. However, the incidence of false positive results was rather high (9.43%). The public health importance of the isolates obtained and the application of the rapid presumptive test at the farm level are discussed.

Abattoirs↗

PubMed1978

A model of salmonella enteritis: the behaviour of Salmonella enteritidis in chick intestine studies by light and electron microscopy.

Salmonella enteritidis was injected into isolated "loops" of duodenum, midgut and ileocaeca in anaesthetized 1-day-old chicks. Using light microscopy with conventional staining and fluorescent antibody techniques, the organism were observed in increasing numbers in the epithelium and lamina propria of each region between 2 and 12 h after inoculation. The potential ability of the salmonellas to enter the mucosa at any level of the intestine was thus demonstrated. The penetration of caecal epithelium by the organisms was studied by electron-microscopy. Uptake of salmonellas was associated with evaginations which formed at the luminal surface of the epithelium. In the epithelial cells, the bacteria were enclosed within membrane-bound vacuoles and appeared undamaged by intracellular passage. Surface evaginations almost completely replaced the brush border in regions where large numbers of the organisms were involved. Occasional salmonellas were found in the lamina propria both free and intracellularly. Results of culture and light microscopy following oral and intracloacal inoculation are also presented.

Animals↗

PubMed1986

Effects of splenectomy on the retention of Salmonella enteritidis and on the hemopoietic response to Salmonella infection.

Salmonella infection induces a marked increase in the splenic granulopoiesis, but causes a reduction in hemopoiesis in the bone marrow. In this study, effects of Salmonella enteritidis infection on hemopoietic stem cells were examined in splenectomized (SX-) mice. Splenectomy emphasized hemopoietic damage in the bone marrow caused by Salmonella infection. Total nucleated cells, pluripotent stem cells (CFUs) and granulocyte-macrophage progenitor cells (GM-CFC) in the bone marrow of SX-mice all decreased markedly compared with sham-splenectomized (NX-) mice, and the recovery from the decline was also delayed. Thus, neither enhancement of the granulopoiesis nor granulopoietic recovery in the bone marrow was observed to compensate the granulopoietic response in the spleen. Splenectomy also resulted in a longlasting retention of Salmonella in the liver. The observations indicate that the spleen is the major organ to respond to bacterial invasion in regard to enhanced granulopoiesis and hence enhanced bacterial clearance.

Animals↗

PubMed1984

Depression of resistance against Salmonella infection in sarcoma 180-bearing mice and its restoration by Salmonella mini-cells.

The reduction of resistance against Salmonella infection was resulted from the reduction of macrophage activities in Sarcoma 180-bearing mice. Mean survival day of S180-bearing mice was markedly reduced to 1.4 +/- 0.5 days after the challenge with 1 X 10(8) of Salmonella typhimurium LT2 cells in contrast with 6.8 +/- 1.9 days of normal mice. Eighty percent of S180-bearing mice died within 14 days after the challenge with 1 X 10(6) of LT2 cells, whereas all of normal mice survived more than 30 days after the challenge with 3 X 10(6) or less of LT2 cells. Chemotactic and O2- producing activities of macrophages collected from S180-bearing mice which were treated with Salmonella mini-cells restored to normal level. Bactericidal activity of macrophages was also restored by the mini-cell treatment. The restoration of the resistance to Salmonella was accompanied with increases of macrophage activities.

Animals↗

PubMed1981

[Salmonella bruck: a new salmonella-serotype (6,7:z:l, w) (author's transl)].

A new Salmonella serotype (S. 6,7:z:l,w) was isolated from a stool specimen of a 40 years old businessman after a several weeks journey in Nigeria with a two days stay in Lagos. The strain was finally confirmed as a new Salmonella serotype on January 1th, 1980, by Prof. Le Minor, International Salmonella Center, Paris. The strain was introduced as Salmonella bruck into the Kaufmann-White-Scheme, Supplément No. XXIII (1979).

Adult↗

PubMedDate not supplied

Synergism of lactate and succinate as metabolites utilized by Veillonella to inhibit the growth of Salmonella typhimurium and Salmonella enteritidis in vitro.

The inhibition of salmonellae growth by a Veillonella bacterium isolated from the cecal contents of adult chickens was examined. The Veillonella isolate was grown on an agar medium supplemented with 175 mumol of lactate or succinate/ml. Either 0, 100, 125, 150, or 175 mumol of succinate/ml was added to the lactate medium; either 0, 100, 125, 150, or 175 mumol of lactate/ml was added to the succinate medium; and the pH of all media was adjusted to 6.0. Agar overlays of Veillonella cultures grown on the media were inoculated with Salmonella typhimurium or S. enteritidis. The largest zones of inhibition of salmonellae growth were produced by Veillonella cultures grown on medium supplemented with 175 mumol/ml of both lactate and succinate. The widths of the zones of inhibition decreased as the concentration of lactate was reduced in the succinate medium and as the concentration of succinate was reduced in the lactate medium. Analyses of lactate broth and succinate broth inoculated with Veillonella indicated that inhibition of salmonellae growth on the agar media was related to the production of volatile fatty acids by Veillonella, the presence of residual succinate in the media, and the final pH of the media.

Analysis of Variance↗

PubMed1994

[The effectiveness of Salmonella immunization of broiler breeders on the Salmonella colonization of the animals and their progeny after experimental oral infection].

The immunization of broiler breeder birds with Salmonella typhimurium live or inactivated vaccines (orally and/or parenterally administered) resulted in a considerable antibody response. Maternally produced antibodies were transferred via egg to the progeny. But the transferred antibodies did not increase considerably the resistance of 1 day old chickens to oral Salmonella typhimurium infection. The results of the oral challenge of the broiler breeder birds showed the protective effect induced by the oral immunisation with the Salmonella live vaccine strain. This protection is expressed by a reduced number of salmonella organisms in the caeca and internal organs.

Animals↗

PubMed1993

[Control of salmonella infections in animal herds--basis for a reduction of salmonella entries into food].

Control measures against Salmonella infections in livestock are discussed on the basis of an epidemiological classification of Salmonella serovars important for animals and/or humans. Special attention is paid to immunoprophylaxis carried out additionally to generally accepted zoo sanitary measures. Available Salmonella vaccines are described and their major characteristics discussed briefly. Schemes are presented for the administration of vaccines in cattle, pigs and poultry. They have to be rationally integrated into general control concepts. They should serve as recommendations for the practical use in animal farms. It is concluded that given consequent combination and enforcement of the described measures the occurrence of Salmonella serovars important for animals and/or humans can be reduced decisively in livestock, thus minimizing introduction into the food chain for the sake of improved consumer protection.

Animals↗

PubMedDate not supplied

[The use of a live Salmonella bivalent vaccine for decreasing the circulation of salmonellae in a poultry plant].

S. typhimurium (expressing antigen 09 of S.dublin) recombinant vaccine strain was tested at a large poultry-breeding farm under the conditions of permanent circulation of salmonellae. The oral immunization of laying hens in three administrations with doses of 5 x 10(8), 5 x 10(9) and 5 x 10(9) microbial cells induced an increase in titers of antibodies only to group D salmonellae, while in immunized chickens (each receiving a dose of 3 x 10(8) microbial cells) antibodies to both group B and group D salmonellae were detected. The vaccination of laying hens and chickens produced a protective effect due to the development of immunity and the decrease of Salmonella contamination of eggs laid by immunized hens, thus reducing the risk of infection at incubator stations. Total mortality during the first 3 months of life was essentially lower (p < 0.001) among immunized chickens (4.41 +/- 0.09%) than in the control group of nonimmunized chickens (5.91 +/- 0.10%).

Administration, Oral↗

PubMedDate not supplied

Heterophil response to intraperitoneal challenge with invasion-deficient salmonella enteritidis and Salmonella-immune lymphokines.

The present work compared the accumulation of intraperitoneal heterophils in day-of-hatch chicks following treatment with Salmonella enteritidis-immune lymphokine (ILK) and challenge with various strains of Salmonella enteritidis (SE). Day-of-hatch chicks received ILK by intraperitoneal injection and were challenged 1 hr later by intraperitoneal inoculation with one of the following SE strains: a wild-type, SE 890034-3; a delta cya-12 delta cyp-11 avirulent vaccine strain, chi 4357; and an invasion-deficient strain, InvA::kan, chi 4420. Four hours after challenge heterophils were recovered from the peritoneal cavity by lavage. The concentration of heterophils in the recovered lavage fluid was determined. Heterophil concentrations increased in response to challenge with each SE strain but there was a lower response to the invasion-deficient strain. The difference was statistically significant. This diminished heterophil response to challenge with invasion-deficient salmonellae supports existing evidence that the initial defensive reaction occurs at the earliest stages of the Salmonella-host interaction.

Analysis of Variance↗

PubMed1981

[Active immunization to experimental salmonellosis in mice protective properties of Salmonella R mutants against infection with different pathogenic Salmonella species (author's transl)].

Mice (NMRI) were immunized twice with acetone-killed bacteria from 13 different Salmonella R-mutant and 6 Salmonella S form strains. Of the R mutants one strain was a semirough mutant, 9 strains belonged to the chemotype Ra, one to chemotype Rb2 and 2 to chemotype Re. Of the S forms 2 strains derived from serological group B, 2 from group D1 and one strain from each of group C1 and C2. Ten days after immunization the animals were challenged with increasing numbers of S-form bacteria (the same S strains as those used for immunization) administered intraperitoneally. The virulence (LD50) of the strains used was between 6 x 10(2) and 3 x 10(5) cells. The results show that every mutant was capable of affording protection to the S-form bacteria used, i.e. the protection was not confined to the species used for immunization; nevertheless differences in the degree of protection were present. These differences were found both in the ability of the different mutants to protect towards the same infecting microorganism and in the protection obtained by individual mutants towards infection with the different S-forms. With certain strains a relatively high degree of protection was obtained, with others the protection was low compared to that seen with homologous S form vaccines. In infection with s. typhimurium, unlike infection with other S-forms, the homologous R mutants were superior to the other mutants in their immunizing properties. Immunization with heterologous S-forms yielded similar results as those obtained with R mutants. S-forms with identical O-antigens were not necessarily comparable in their protective properties. Although the protective effect of R mutants was generally lower than that produced by homologous S-form vaccines, the present results show that in a few cases an equally high protection may also be obtained by R mutants. The present results lead to the conclusion that the cell-surface of Salmonella contains, in addition to the known antigens, other components playing an important role in inducing immunity to infection. A partial divergence in the pattern of such components among the different vaccines, would explain the extension of immunity obtained by the heterologous species also.

Animals↗

PubMed2000

Antimicrobial drug resistance in non-typhoidal salmonellas from humans in England and Wales in 1999: decrease in multiple resistance in Salmonella enterica serotypes Typhimurium, Virchow, and Hadar.

In 1999 the incidence of multiple drug resistance (to four or more antimicrobials) in non-typhoidal salmonellas from humans in England and Wales fell in isolations of Salmonella enterica serotypes Typhimurium, Virchow, and Hadar. This fall has been most noticeable in S. Typhimurium, where 59% of isolates were multiresistant compared to 81% in 1996. The main reason for this has been a 75% decline in isolations of multiply-resistant S. Typhimurium definitive phage type (DT) 104 (MR DT104) since 1996. Nevertheless MR DT104 remains second to S. Enteritidis phage type 4 as the most common strain in cases of human salmonellosis in England and Wales. Multiple resistance has also remained high in S. Hadar, with 49% of isolates resistant to four drugs or more compared to 56% in 1996. Isolates with decreased sensitivity to ciprofloxacin (minimal inhibitory concentration: 0.25-1.0 mg/L) have increased in incidence in S. Enteritidis, S. Virchow, and S. Hadar; in S. Hadar 70% of isolates were resistant to ciprofloxacin at this level. It is hoped that Codes of Practice introduced by some pharmaceutical companies, governments, professional organisations, and others to combat the unnecessary prophylactic use of fluoroquinolones in animal husbandry will not result in a reduction in the incidence of resistance to ciprofloxacin in salmonella organisms causing infections in humans.

Anti-Bacterial Agents↗

PubMed1991

Antimicrobial susceptibilities and beta-lactamase production of Hong Kong isolates of gastroenteric salmonellae and Salmonella typhi.

We examined the in-vitro antibiotic susceptibility of 760 gastroenteric salmonellae and 36 strains of Salmonella typhi isolated in Hong Kong between 1985 and 1988. S. typhi remained susceptible to all the antibiotics tested except for one isolate resistant to chloramphenicol, another to kanamycin and co-trimoxazole, and a third to nalidixic acid. In contrast, resistance and multiple resistance has increased significantly in gastroenteric salmonellae over the last ten years. Seventeen percent were resistant to ampicillin, 61% to tetracycline, 23% to chloramphenicol and 8% to gentamicin. Many ampicillin-resistant strains remained resistant to ampicillin even in the presence of sulbactam (69%) or clavulanic acid (25%). More than 50% of isolates were resistant to two or more antibiotics and one isolate was resistant to eleven. Ampicillin-resistance was usually due to the production of TEM-1 or OXA-1 beta-lactamases but a few isolates produced AER-1, PSE-1 or PSE-2. Genetic determinants for these enzymes were usually borne on plasmids ranging in size from 2 to 143.7 Md but half of the OXA-1 genes were chromosomally located.

Ampicillin Resistance↗

PubMedDate not supplied

Use of a live attenuated Salmonella typhimurium vaccine to protect hens against Salmonella enteritidis infection while undergoing molt.

Previous studies demonstrated that Salmonella enteritidis infections in hens undergoing molt via feed withdrawal were more severe than in full fed hens. We conducted two trials to determine if immunizing specific-pathogen-free, Salmonella-culture-negative hens via aerosol exposure to MeganVacl, a commercially available attenuated Salmonella typhimurium vaccine, would reduce transmission of S. enteritidis from infected hens to uninfected but contact-exposed hens during a molt. In trial 1, one group of hens received two aerosol doses of vaccine 2 wk apart whereas a second group of hens remained nonvaccinated. In trial 2, the vaccinated group received only one dose of vaccine. Two weeks after the final immunization, feed was removed from all the hens, and on day 4, the center hen in rows of 11 hens received a dose of 3 x 10(5) (trial 1) or 1.3 x 10(6) (trial 2). Transmission to the unchallenged hens was followed 3, 10, 17, and 24 days later. Vaccination reduced the horizontal spread of S. enteritidis in vaccinated hens compared with their nonvaccinated counterparts, with vaccinated hens shedding significantly less S. enteritidis on day 10 postchallenge in trial 1 and on days 3, 10, 17, and 24 in trial 2. Recovery of S. enteritidis from ovaries was significantly reduced in the vaccinated hens in trial 1 and from livers/spleens, ovaries, and cecum in trial 2. These studies indicate that immunization of hens with a live S. typhimurium vaccine could help reduce S. enteritidis problems during a molt situation.

Aerosols↗

PubMed2002

Cytopathic effects observed upon expression of a repressed collagenase gene present in Salmonella and related pathogens: mimicry of a cytotoxin from multiple antibiotic-resistant Salmonella enterica serotype Typhimurium phagetype DT104.

Recently, we reported that certain strains of Salmonella enterica serovar Typhimurium phagetype DT104 (DT104) secrete a putative cytotoxin. While searching for the gene that encodes this toxin, we noted a previously reported but uncharacterized DNA fragment (clg) in Salmonella that could be potentially relevant to cytotoxin-like activity. Therefore, we cloned and expressed clg in cytotoxin-negative Escherichia coli and Salmonella and subsequently assessed the bioactivity of Clg in vitro and in vivo. Lysates containing Clg from both expression hosts exerted cytopathic effects on murine enterocytes while semi-purified Clg was determined to be cytopathic to HEp-2 cells. Sequence and RT-PCR analyses of the clg gene indicated that a homologue of clg exists in different Gram-negative bacteria although the gene is not expressed in vitro. Although Clg-mediated lesions are similar to those mediated by the DT104 cytotoxin, further investigations are necessary to examine the relationship between these two proteins in DT104. Nonetheless, we report here a defined Salmonella protein that is capable of inflicting damage on tissue culture cells and murine enterocytes.

Animals↗