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PubMed2004

Observations on Salmonella contamination of eggs from infected commercial laying flocks where vaccination for Salmonella enterica serovar Enteritidis had been used.

Eggs were collected monthly from 12 cage-layer flocks on four farms where Salmonella Enteritidis was present in vaccinated flocks despite vaccination with an S. Enteritidis bacterin. Where possible, hens were also taken for culture at the end of the laying period, and faecal and environmental samples were taken from the laying houses before and after cleaning and disinfection. Twenty-four batches of six egg shells from the 13 652 tested (0.18% [0.11 to 0.26 CI(95)] single egg equivalent) were positive for S. Enteritidis and 54 (0.40% [0.30 to 0.52 CI(95)] single egg equivalent) for other serovars. Six batches of 13 640 (0.04% [0.02 to 0.10 CI95] single egg equivalent) egg contents, bulked in six egg pools, contained S. Enteritidis and three batches contained other serovars. In addition three further batches contained S. Enteritidis in both contents and shells, and two other batches contained other serovars in both. The total level of contamination by S. Enteritidis of both contents and shells found in vaccinated flocks was therefore 33 batches/13 682 eggs(0.24% [0.17 to 0.34 CI(95)] single egg equivalent). The total of contamination for any Salmonella serovar was 92 batches/13 682 eggs (0.68% [0.55 to 0.84 CI(95)] single egg equivalent). These results contrast with the findings of testing of eggs from three unvaccinated flocks prior to this study where 21 batches of egg shells from a total of 2101 eggs (1.0% [0.63 to 1.56 CI(95)] single egg equivalent) and six batches of contents from 2051 eggs (0.29% [0.11 to 0.64 CI95] single egg equivalent) were contaminated with S. Enteritidis. S. Enteritidis was found in 67/699 (9.6%) of vaccinated spent hens and 64/562 (11.4%) of bulked fresh faecal samples taken from laying houses. Failure to adequately clean and disinfect laying houses and to control mice appeared to be a common feature on the farms.

Animal Husbandry↗

PubMed1993

Role of egg consumption in sporadic Salmonella enteritidis and Salmonella typhimurium infections in Minnesota.

The incidence of Salmonella enteritidis infections has increased in the eastern United States, and consumption of undercooked eggs has been associated with outbreaks of S. enteritidis. In Minnesota, the incidence of S. enteritidis infections doubled from 1980 to 1990; however, no egg-associated outbreaks were identified. A case-control study was conducted to examine potential exposures for S. enteritidis and Salmonella typhimurium infections in Minnesota adults. Sporadic cases of S. enteritidis (odds ratio [OR], 5.2; 95% confidence interval [CI], 1.9-14.2; P = .003) and S. typhimurium infection (OR, 2.4; CI, 1.1-5.5; P = .03) were more likely to have consumed undercooked eggs or egg-containing foods during the 3 days before onset of illness compared to a similar reference period for controls. In addition, the extent to which eggs were cooked was directly associated with illness (chi 2 test for trend, P < .001). These findings demonstrate that eggs are important vehicles for S. enteritidis and S. typhimurium, even in the absence of recognized outbreaks.

Adolescent↗

PubMed1983

Generalized transduction between Salmonella typhi and Salmonella typhimurium by phage j2 and characterization of the j2 plasmid in Escherichia coli.

Phage j2, a P1-like phage in Salmonella typhi, was heteroimmune to phage P1 and existed in the lysogenic state as a plasmid of molecular size 58.6 MDal. The phage j2 plasmid was incompatible with the P1 plasmid (IncY group). A j2-sensitive mutant of Salmonella typhimurium LT2 was isolated by transduction of j2Ap phage into LT2 followed by curing of the prophage. The mutant was used to demonstrate transduction between S. typhi and S. typhimurium by phage j2.

Coliphages↗

PubMed2000

Some safety aspects of Salmonella vaccines for poultry: in vivo study of the genetic stability of three Salmonella typhimurium live vaccines.

Live vaccine strains of Salmonella should be avirulent, immunogenic and genetically stable. Some isolates of three commercially available live vaccine strains of Salmonella typhimurium, sampled during a study on their persistence in a vaccinated flock of chickens, were analyzed for genetic stability using macrorestriction analysis of their genome. Two out of the three vaccine strains showed genetic instabilities. Two of the 51 isolates of Zoosaloral vaccine strain and nine of the 32 analyzed isolates of chi(3985), a genetically modified organism, were variants and showed different macrorestriction profiles.

Animals↗

PubMed1976

Nonspecific resistance against infection with Salmonella typhi and Salmonella typhimurium induced in mice by cord factor (trehalose-6,6'-dimycolate) and its analogues.

Mice pretreated intraperitoneally with trehalose-6,6'-dimycolate (cord factor) were protected against an intraperitoneal challenge with Salmonella typhi strain Ty2 or Salmonella typhimurium strain SR 11. The nonspecific resistance to S. typhi and S. typhimurium was still detectable 7 and 14 days, respectively, after administration of cord factor. The effect of cord factor was local. Synthetic analogues of cord factor--trehalose-6,6'-dipalmitate and trehalose monopalmitate--also induced nonspecific resistance to the above virulent bacteria. The results are discussed.

Animals↗

PubMed1992

Salmonella choleraesuis and Salmonella typhimurium associated with liver cells after intravenous inoculation of rats are localized mainly in Kupffer cells and multiply intracellularly.

Male Sprague-Dawley rats were inoculated intravenously with Salmonella choleraesuis or Salmonella typhimurium and used over 3 consecutive days to produce highly enriched (greater than 95% homogenous) preparations of Kupffer and mononuclear cells (KC), liver endothelial cells (LEC), and hepatocytes. The methods involved collagenase perfusion of the liver in situ, differential centrifugation of liver cells over a Percoll gradient, and selective attachment of the cells to plastic or to culture dishes coated with collagen. The different cell preparations were then assayed for the number and location, intracellular or extracellular, of associated viable bacteria. Most of the viable bacteria recovered were associated with KC and were mainly intracellular. The intracellular bacteria in KC from rats infected with either bacterial strain increased about 20- to 50-fold over 2 days. Some of the bacteria associated with LEC and in some experiments with hepatocytes also survived treatment with gentamicin and increased in number with time. Intracellular bacteria were readily visualized in KC by light microscopy and transmission electron microscopy. On rare occasions, bacteria were seen within LEC from rats infected with S. choleraesuis but not from those infected with S. typhimurium. Microcolonies of S. typhimurium but not of S. choleraesuis were occasionally found on the surface of some LEC. Bacteria were not seen within or on the surface of hepatocytes by transmission or scanning electron microscopy. The integration of microscopic and viability data suggested that most intracellular S. choleraesuis organisms in KC had been killed whereas most intracellular S. typhimurium organisms were viable.

Animals↗

PubMed1993

Oral vaccination of calves with an aromatic-dependent Salmonella dublin (O9,12) hybrid expressing O4,12 protects against S. dublin (O9,12) but not against Salmonella typhimurium (O4,5,12).

Three groups of six calves each, 5 to 7 weeks old, were orally vaccinated with the live aromatic-dependent delta aroA Salmonella dublin (O9,12) hybrid strain SL7103 with the O4,12-specifying rfb gene cluster from Salmonella typhimurium. SL7103 was given in three weekly doses, increasing from 2 x 10(9) to 1 x 10(11) bacteria per ml, was well tolerated, and caused mild, short-term temperature increases which diminished with each immunization. The strain was shed for up to 1 week. Strain SL7103 elicited significant (P < 0.001) and equal anti-S. dublin and -S. typhimurium lipopolysaccharide serum antibody responses and skin delayed-type hypersensitivity immune responses. Six vaccinated calves orally challenged with 10(10) CFU (equivalent to 1,000 50% lethal doses) of the virulent parent strain S. dublin SVA47 were protected and experienced only transient fever and mild mucoid diarrhea. However, six vaccinated calves orally challenged with 3 x 10(9) CFU and another six challenged with 3 x 10(8) CFU (equivalent to 1,000 50% lethal doses) of the virulent S. typhimurium SVA44 became bacteremic with a profuse hemorrhagic diarrhea and had to be sacrificed within 2 to 7 days. The results suggest that the S. typhimurium antilipopolysaccharide immunity was insufficient to provide a solid protective efficacy against oral S. typhimurium infection. The immunohistopathological examination revealed that S. typhimurium SVA44 could be found in all layers of the intestinal mucosa and the lymphatic tissues of the Peyer's patches. In contrast, S. dublin SVA47 was found predominantly in the columnar enterocytes of the jejunum and ileum and the follicle-associated epithelium over the Peyer's patches. In addition, SVA47 was found in the glandular tissues of the duodenal and tonsillar areas and in the lungs. This suggests that the S. typhimurium and S. dublin strains have different virulence traits determining their tissue localization and dissemination.

Animals↗

PubMed1995

Characterization of intestinal invasion by Salmonella typhimurium and Salmonella dublin and effect of a mutation in the invH gene.

The relative levels of invasiveness of two bovine isolates each of Salmonella typhimurium and Salmonella dublin and of invH mutants of S. typhimurium were determined in MDCK and Int 407 cultured-cell assays and in bovine ileal loops. S. dublin was found to be significantly less invasive in cultured cells than S. typhimurium, but this difference was not observed in bovine intestines. The invH mutants exhibited a significant reduction in invasion in both cultured cells and bovine intestines. The invasive phenotypes of the strains were confirmed by fluorescent microscopy and scanning and transmission electron microscopy. The wild-type strains were observed in the laminae propriae of the intestinal villi, while in contrast the invH mutants were generally associated with the enterocyte layer. The degree of damage in the bovine ileum was related to the magnitude of the invasion. There was no difference in the amount of S. typhimurium or S. dublin recovered from the bovine ileum either with or without Peyer's patches 3 h after inoculation of the loop.

Animals↗

PubMed2002

Characterization of Salmonella enterica derivatives harboring defined aroC and Salmonella pathogenicity island 2 type III secretion system (ssaV) mutations by immunization of healthy volunteers.

The attenuation and immunogenicity of two novel Salmonella vaccine strains, Salmonella enterica serovar Typhi (Ty2 Delta aroC Delta ssaV, designated ZH9) and S. enterica serovar Typhimurium (TML Delta aroC Delta ssaV, designated WT05), were evaluated after their oral administration to volunteers as single escalating doses of 10(7), 10(8), or 10(9) CFU. ZH9 was well tolerated, not detected in blood, nor persistently excreted in stool. Six of nine volunteers elicited anti-serovar Typhi lipopolysaccharide (LPS) immunoglobulin A (IgA) antibody-secreting cell (ASC) responses, with three of three vaccinees receiving 10(8) and two of three receiving 10(9) CFU which elicited high-titer LPS-specific serum IgG. WT05 was also well tolerated with no diarrhea, although the administration of 10(8) and 10(9) CFU resulted in shedding in stools for up to 23 days. Only volunteers immunized with 10(9) CFU of WT05 mounted detectable serovar Typhimurium LPS-specific ASC responses and serum antibody responses were variable. These data indicate that mutations in type III secretion systems may provide a route to the development of live vaccines in humans and highlight significant differences in the potential use of serovars Typhimurium and Typhi.

Bacterial Proteins↗

PubMed1979

Deoxyribonucleic acid adenine and cytosine methylation in Salmonella typhimurium and Salmonella typhi.

The methylations of adenine in the sequence -GATC- and of the second cytosine in the sequence - [Formula: see text] - were studied in Salmonella typhimurium and in Salmonella typhi. The study was carried out by using endonucleases which restrict the plasmid pBR322 by cleavage at the sequences -GATC- (DpnI and MboI) and - [Formula: see text] - (EcoRII). The restriction patterns obtained for this plasmid isolated from transformed S. typhimurium and S. typhi were compared with those of pBR322 isolated from Escherichia coli K-12. In E. coli K-12, adenines at the sequence -GATC- and the second cytosines at - [Formula: see text] - are met hylated by enzymes coded for by the genes dam and dem, respectively. From comparison of the restriction patterns obtained, it is concluded that S. typhimurium and S. typhi contain genes responsible for deoxyribonucleic acid methylation equivalent to E. coli K-12 genes dam and dcm.

Adenine↗

PubMed1968

Recall of immunity in mice vaccinated with Salmonella enteritidis or Salmonella typhimurium.

Mice were immunized with living Salmonella enteritidis or S. typhimurium and then were reinfected 8, 30, 60, and 150 days later with streptomycin-resistant strains of S. enteritidis, S. typhimurium, or a mixture of the two organisms. The level of resistance at the time of challenge and the rate at which resistance was recalled in late convalescence was determined by daily liver and spleen counts of the challenge population. An immediately effective specific antibacterial immunity was maintained only while the vaccinating strain could still be detected in the liver and spleen. Reinfection of vaccine-free mice with the homologous organism caused a rapid recall of antibacterial immunity (within 3 days), but the response to the heterologous organism was much slower (5 to 8 days). Simultaneous injection of both pathogens into the vaccinated mice resulted in liver and spleen growth curves which resembled those obtained when the two organisms were administered separately. The implications of these growth studies in the development of specific cellular immunity to Salmonella infections are discussed.

Animals↗

PubMedDate not supplied

Changing patterns of Salmonella serovars: increase of Salmonella enteritidis in São Paulo, Brazil.

Serovars of a total of 5,490 Salmonella strains isolated during the period of 1991-95, from human infections (2,254 strains) and from non-human materials (3,236 strains) were evaluated. In the studied period, 81 different serovars were determined among human isolates. Salmonella Enteritidis corresponded to 1.2% in 1991, 2% in 1992, 10.1% in 1993, 43.3% in 1994, and 64.9% in 1995 of all isolates. A significant rise on the isolation of this serovar was seen since 1993 linked to food poisoning outbreaks. It is reported also an increase on the isolation of S. Enteritidis from blood cultures, associated mainly with patients with immunodeficiency syndrome. S. Enteritidis was prevalent among one hundred and thirty different serovars isolated from non-human sources. Increasing number of isolation of this serovar was seen from shell eggs, breeding flocks and from environmental samples. It is also reported a contamination of commercial feed stuffs by S. Enteritidis which represents a major concern for Brazilian poultry industry.

Animals↗

PubMed2004

Colonization of reproductive organs and internal contamination of eggs after experimental infection of laying hens with Salmonella heidelberg and Salmonella enteritidis.

Internal contamination of eggs laid by hens infected with Salmonella enteritidis has been a prominent international public health issue since the mid-1980s. Considerable resources have been committed to detecting and controlling S. enteritidis infections in commercial laying flocks. Recently, the Centers for Disease Control and Prevention also reported a significant association between eggs or egg-containing foods and S. heidelberg infections in humans. The present study sought to determine whether several S. heidelberg isolates obtained from egg-associated human disease outbreaks were able to colonize reproductive tissues and be deposited inside eggs laid by experimentally infected hens in a manner similar to the previously documented behavior of S. enteritidis. In two trials, groups of laying hens were orally inoculated with large doses of four S. heidelberg strains and an S. enteritidis strain that consistently caused egg contamination in previous studies. All five Salmonella strains (of both serotypes) colonized the intestinal tracts and invaded the livers, spleens, ovaries, and oviducts of inoculated hens, with no significant differences observed between the strains for any of these parameters. All four S. heidelberg strains were recovered from the interior liquid contents of eggs laid by infected hens, although at lower frequencies (between 1.1% and 4.5%) than the S. enteritidis strain (7.0%).

Animals↗

PubMed1991

Successive Salmonella give and Salmonella typhi infections, laboratory-acquired.

A case of laboratory-acquired typhoid fever is described. The case was complicated by a self-limiting Salmonella give gastroenteritis which may also have been laboratory-acquired and which occurred during the incubation period of the Salmonella typhi infection. The symptoms of typhoid were not sufficiently severe for the patient to seek medical attention and she was recovering from the infection when the typhoid bacillus was isolated from her stools. The mode of transmission of the S. typhi was presumed to be a laboratory infection from an unknown source. Although there was no obvious breakdown in safe laboratory techniques, the infecting dose of S. typhi is known to be small and the dangers of handling specimens which may contain this bacterium are emphasized.

Adult↗

PubMed1975

[Study of Salmonella cultures. IV. Immunogenicity of Salmonella resistant to antibiotics].

Three avirulent and 5 slightly virulent for birds mutants of Salmonella enteritidis and Salmonella braenderup, resistant to streptomycin (S), chlorteracyclin (CT), and chloramphenicol (Ch) were used in the production of live vaccines. The latter were tested for immunogenicity on albino mice and birds. On the eighth and 15th day following vaccination the protein fractions in the blood serum of the birds were followed up through electrophoresis on agar gel, while the agglutinin titer was determined by means of test tube agglutination. The experimental results were mathematically processed with the use of statistical methods. All slightly virulent and resistant to antibiotics mutants showed strong immunogenic properties and gave protection (preventing death) to 76.2-81.82 per cent of the mice. Of the avirulent mutants one showed moderate virulence giving protection to 71.43 per cent of the animals. Tested on 110-day-old chickens the avirulent mutants gave protection to 80 per cent of them. The average titers of the blood serum antibodies of birds vaccinated with immunogenic mutants, and the average percent values of the gamma-globulin fractions were higher on the eighth than on the 15th day. The protein fractions showed changes in the albumin and the gamma-globulin. The rate of correlation between these indices, as shown by the coefficient of correlation, is high (rxy = - 0.843). In this case the negative value of rxy in the equation points to the negative link between the characters.

Animals↗

PubMed2001

Competitive exclusion against Salmonella gallinarum of Salmonella enteritidis infected chickens.

To evaluate the degree of competitive exclusion against Salmonella gallinarum(S. gallinarum) of Salmonella enteritidis(S. enteritidis) infected chickens, fifty-six, 4-week old Hyline layer suspected of S. enteritidis infection were challenged with S. gallinarum. All chickens were tested for S. enteritidis isolation using cloacal swabs and serum plate agglutination test using S. enteritidis Ag. before challenge and classified into four groups(SE isolated, SE nonisolated, SE seropositive and SE seronegative). None of the SE isolated and the SE seropositive groups died after challenge and the average weight gains were 245.5g and 254.6g, respectively. But in the SE nonisolated and the SE seronegative groups, mortality was 18.2% and 20.6% and the average weight gains were 150.1g and 111.2g. The incidence of reisolation of S. gallinarum of the SE isolated and the SE seropositive groups were 41.7% and 47.6% from liver, 33.3% and 47.6% from spleen and 8.3% and 14.3% from cecum, respectively, and the SE nonisolated and the SE seronegative group were 63.6% and 64.7% from liver, 84.1% and 88.2% from spleen and 47.7% and 52.9% from cecum. The serological response of the SE isolated and the SE seropositive groups hardly changed from 75.0 and 81.8% before challenge to 75.0 and 85.7% after. But, the other two groups were found to be significantly higher after challenge and increased from 0 and 18.2% to 100%. Consequently, S. enteritidis preinfected chickens were found to be significant different in terms of mortality, weight gain, reisolation of S. gallinarum and serological response compared to noninfected chickens. Moreover, our study shows that S. enteritidis infected chickens appear strong competitive exclusion against the colonization of S. gallinarum.

Animals↗

PubMedDate not supplied

[Biological properties of salmonellae and local immunity in Salmonella infection].

The comparative study of the biological properties of S. enteritidis and S. typhimuruim, isolated from patients and convalescent carriers, was carried out. Factors inactivating the components of the local immunity of the intestine (lysozyme, complement, lactoferrin, IgG, IgM and IgA) were detected in the causative agents of Salmonella infections. The spread and expression degree of properties of a causative agent were serovar-depended: high penetration characteristics and the expression of anti-lactoferrin and anti-immunoglobulin activity were characteristic of S. typhimurium. S. enteritidis strains isolated from patients with carrier state formed in the convalescence period were found to have higher persistence level. In co-profiltrates obtained from carriers at the peak of the disease and during convalescence lower levels of IgM, IgG, sIgA, complement and lactoferrin were determined in comparison with those in coprofiltrates obtained from patients in whom no subsequent carrier state was formed. These results indicate that an increase in the persistence of salmonellae, occurring simultaneously with the local immunodeficiency, contributes to the prolonged survival of bacteria in the intestine.

Antibodies, Bacterial↗

PubMed1985

Epidemiological analysis of Salmonella typhi-murium infections on the basis of laboratory methods. II. Resistance to antibiotics and R-plasmid carrier state in Salmonella typhi-murium isolated in Hungary in the period 1974 to 1981.

Phage and biochemical typing of Salmonella typhi-murium strains performed in the course of the Salmonella Surveillance Programme were completed with examinations on resistance to antibiotics and R-plasmids. A total of 15 600 strains of human, animal and water origin were tested between 1975 and 1981 and most of the monoresistant strains were found among the animal strains (73.6%-94.9%), while double resistance was the most frequent among the human strains (5.5%-25.5%) and multiresistance occurred in the highest ratio (2.8%-25.6%) among the strains of water origin. Tetracycline resistance was the most frequent in all the three materials. The curves representing the incidence of tetracycline (Tc), chloramphenicol (Cm), streptomycin (Sm), kanamycin (Km) resistance were similar to the curve of multiple resistance and differed from the curve showing the incidence of ampicillin (Ap) resistance. Gentamicin resistance was found only among human strains (in 0.3 and 0.7%), strains resistant to nitrofurantoin and co-trimoxazole occurred among strains of human and water origin in low percentages. The most common antibiotic resistance patterns of the multiple resistant strains were Tc, Cm, Sm, Km, Ap, Su; Tc, Sm, Su; Sm, Km, Ap, Su. Multiple resistant strains belonged in the majority to phage type nt (not typable) and 2b. Out of the examined 512 S. typhi-murium strains resistant to antibiotics, the presence of R-plasmid was demonstrated in 408 strains (i.e. 79.7%). The R-plasmids, derived from strains of human, animal and water origin, of phage type nt, biotype 3 (nt/3) isolated in 1979, were characterized according to the resistance determinants, fi-character, incompatibility-group, phage-inhibition and molecular weight. Two kinds of R-plasmids were carried by three human strains (FI and H, FI and alpha). R-plasmids belonging to Inc P and Inc H were carried by one animal strain. Strains isolated from sewage carried R-plasmids of Inc groups H and I alpha. Out of the examined 15 S. typhi-murium strains of phage type 2b, isolated in 1981, the molecular weight for 7 strains was 66 Md and four belonged to Inc I alpha. The R-plasmids derived from 2b/2 strains, isolated in the same county, were identical according to antibiotic resistance determinants, phage inhibition and molecular weight. The molecular weights of R-plasmids derived from 10 strains out of the examined 30 nt strains were also 66 Md and the four examined plasmids belonged also to Inc I alpha.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗