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1.
To determine whether a strain of Salmonella typhimurium (UCD 1755) of equine origin had enterotoxin activity, 2 ml of a cell-free culture lysate of strain UCD 1755 and approximately 10(9) viable strain UCD 1755 organisms were inoculated into ligated small intestinal segments of rabbits. Intestinal segments inoculated with viable strain UCD 1755 organisms and those inoculated with a cell-free culture lysate of strain UCD 1755 had significant (P less than 0.05) accumulations of fluid 10 hours after inoculation when compared with ligated intestinal segments either inoculated with sterile brain-heart infusion broth or left empty. There was not a statistically significant difference between fluid accumulation of intestinal segments inoculated with viable strain UCD 1755 and that of segments inoculated with a cell-free culture lysate of strain UCD 1755. The responses of equine colonic mucosa to culture filtrates of 2 strains of salmonella typhimurium (UCD 1755 and SL 1027) and purified cholera toxin were studied in vitro. Isolated smaples of colonic mucosa were incubated for 4 hours at 37 C in Krebs-Henseleit bicarbonate buffer (KHB) alone, KHB plus culture lysate of strain UCD 1755, KHB plus culture lysate of strain SL 1027, and KHB plus 1 microgram of cholera toxin/ml. Cyclic adenosine monophosphate (cAMP) content of each sample was determined.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
To investigate a possible mechanism involved in the enhancement of Salmonella typhimurium infection in chickens concurrently infected with Eimeria tenella, S typhimurium was given orally to chickens 7 days after E tenella inoculation. The number of viable S typhimurium decreased in the ceca of chickens not inoculated with E tenella, whereas the number gradually increased in the ceca of chickens inoculated with E tenella. Cecal contents were analyzed for pH value, oxidation-reduction potential, and amounts of short-chain fatty acids and bile acids. In the ceca of E tenella-inoculated chickens, the oxidation-reduction potential significantly (P less than 0.05) shifted to the oxidative phase, and the concentration of volatile fatty acids (acetic acid, propionic acid, and butyric acid) significantly (P less than 0.05) decreased. In both aerobic and anaerobic incubations, the number of viable S typhimurium in vitro decreased as the molar concentration of fatty acids increased. Experimental evidence indicated that multiplication of S typhimurium in the ceca of E tenella-inoculated chickens was associated with decreased concentrations of volatile fatty acids.  相似文献   

3.
Two-day-old chicks were orally inoculated with 1 ml of Salmonella typhimurium (10(5) colony-forming units/ml) and divided into four groups. Three groups were fed 2.5% carbohydrates starting on day 1 (arabinose, galactose, and lactose), while the fourth group served as the control. Ceca were obtained from each group at 7, 14, and 21 days. At the end of 14 days, all three carbohydrates statistically reduced Salmonella recovery. However, lactose failed to reduce recovery between day 14 and day 21. Arabinose and galactose continued to show significant reductions of recovery through 21 days. No statistical difference was found between Salmonella recovery from whole ceca (with cecal material) and inverted ceca (washed free of cecal material).  相似文献   

4.
Aromatic-dependent Salmonella typhimurium as modified live vaccines for calves   总被引：29，自引：0，他引：29  
Strains of Salmonella sp with complete nonreverting aromatic biosynthesis (aro) defects are expected to be nonvirulent, in respect to invasive infection, because they need the aromatic metabolites paraaminobenzoate (for making folate) and dihydroxybenzoate (for making enterochelin) which are not available in host tissues. Derivatives with transposon-generated complete nonreverting aro-defects were prepared from 3 mouse-virulent strains of S typhimurium, namely, FIRN, WRAY, and UCD. The latter 2 parent strains originally were isolated from calves and are known to be calf-virulent. The resultant aromatic-dependent (aro-) strains were used to vaccinate 27 calves (2 to 3 weeks old), usually giving 2 doses by the IM route (10(9) bacteria) or orally (1.5 X 10(11)). Vaccination did not cause severe ill effects in any calf. Thus aro- defects cause loss of virulence for calves, as previously shown for mice. Vaccinated and control calves were challenge exposed, usually at 5 weeks of age, by feeding 1.5 X 10(11) cells of 1 of 2 calf-virulent S typhimurium strains, either UCD 108-11 or SL1323. Of the 16 challenge-exposed control calves, all became anorectic and depressed (CNS), and 15 had diarrhea. Fourteen of the 16 died; all tested tissues were bacteriologically culture-positive for Salmonella at necropsy. Vaccination with the live UCD aro- vaccine strain, SL1479 by either of 2 schedules (IM or orally) appeared effective.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
The effect of Corynebacterium parvum on resistance to Salmonella typhimurium infection was evaluated in young chickens. One-day-old chickens were inoculated subcutaneously (SC) or intraperitoneally (IP) with 1.4 mg killed C. parvum and challenged by IP injection with 5.0 X 10(7) S. typhimurium 4 days later. Spleen and bursa of Fabricius weights were not altered in the C. parvum-inoculated chickens. A transient increase in thymus weight occurred 3 days after inoculation with C. parvum. Phytohemagglutinin-elicited cutaneous hypersensitivity was significantly suppressed in the C. parvum-inoculated chickens. Morbidity due to Salmonella infection increased significantly from 15% and 21% in the control groups to 43% and 46% in the chickens inoculated IP or SC with C. parvum. The results indicated that inoculation of 1-day-old chickens with C. parvum suppressed cell-mediated immune responsiveness and decreased resistance to peritoneal infection with S. typhimurium.  相似文献   

6.
F McHan  E B Shotts 《Avian diseases》1992,36(1):139-142
Two groups of 20 chicks each were fed 1% fatty acid continuously starting at 1 day of age, while a control group of 20 chicks received unsupplemented feed. At 2 days of age, chicks were inoculated orally with 1 ml of Salmonella typhimurium (1 x 10(6) colony-forming units/ml). Ceca were obtained from six chicks of each group at 7, 14, and 21 days of age. At 14 days of age, formic and propionic acids had statistically reduced Salmonella recovery by 2.56 logs and 3.09 logs, respectively, compared with controls. At 21 days of age, both test groups showed significant reductions of approximately 3.6 logs compared with controls. There were no statistical differences in body weights among the groups at 21 days of age.  相似文献   

7.
Seventeen ponies were infected with Salmonella typhimurium and then 15 were variously stressed by transportation and/or surgery and 9 were given oxytetracycline. Indications of Salmonella reactivation occurred in all the stressed ponies. Diarrhea due to a reactivation of the Salmonella infection did not develop until greater than 3 days after stress, although maximal shedding of organisms occurred within 24 hours. A neutropenia generally occurred within 24 hours after stress and lasted about 5 days. A rectal temperature greater than 39 C usually did not occur. An increase in serologic titer was noticed in about half of the ponies. Transportation had a major role in reactivating the Salmonella infection, and 1 pony died of peracute colitis. The use of oxytetracycline prolonged the excretion of Salmonella; therefore, this drug should not be used after stress, particularly transportation, in ponies that have diarrhea or are known to be Salmonella carriers.  相似文献   

8.
Inclusion of lactose in the diets of chickens has been determined to reduce cecal colonization with Salmonella typhimurium. We hypothesized, therefore, that dietary lactose may be a practical means for reducing the prevalence of Salmonella contamination of chicken products. Because some strains of Salmonella are atypical and ferment lactose, we investigated the effects of dietary lactose on cecal colonization with lactose-fermenting S typhimurium. Broiler chicks were inoculated intracloacally with Lac+ S typhimurium selected for resistance to novobiocin and rifampicin. The chicks also were inoculated orally with certain anaerobes that do not effectively inhibit colonization by S typhimurium, but do appear essential for lactose mediated inhibition of cecal colonization. Control chicks were not given dietary lactose, and chicks in the experimental group were fed a diet containing 7% lactose. Enumeration of Lac+ S typhimurium in cecal contents revealed dietary lactose to be effective at controlling this organism. Control was correlated with changes in cecal pH and increases in undissociated volatile fatty acids, especially propionic acid.  相似文献   

9.
Twenty-six 4-week-old pigs were randomly allotted to 4 groups: group 1--orally inoculated with Salmonella typhimurium; group 2--orally dosed with S choleraesuis; and groups 3 and 4, with surgically constructed intestinal loops--loops inoculated with either S typhimurium or S choleraesuis. One pig each from groups 1 and 2 was killed at 8, 12, 24, 48, 72, 96, and 120 hours after inoculation. One pig each from groups 3 and 4 was killed at 2, 4, 6, 8, 12, and 24 hours after intestinal loop inoculation. Inoculation of S typhimurium resulted in acute enterocolitis of variable severity, whereas inoculation of S choleraesuis resulted initially in septicemia followed by formation of large necrotic and ulcerative lesions in the colonic mucosa. The most consistent systemic lesion of S choleraesuis infection was interstitial pneumonia and multifocal hepatic necrosis. Salmonella typhimurium and S choleraesuis were ultrastructurally within enterocytes of ligated ileal loops. Intracellular bacteria were morphologically intact, occurred free in the cytoplasm and membrane bound, and caused no detectable cytotoxic effect to the cell. Both S typhimurium and S choleraesuis penetrated the intestinal mucosa and were isolated from mesenteric lymph nodes at 2 hours after inoculation.  相似文献   

10.
Clinical, bacteriological, serological and haematological observations were made on 13 adult ponies orally inoculated with Salmonella typhimurium. The results were compared to two control ponies and four others infected by accidental transmission. The clinical responses in inoculated ponies included pyrexia lasting four days and neutropaenia during the first five days after inoculation followed by a neutrophilia. Pyrexia and neutropaenia was associated with maximal shedding of organisms in the rectal faeces. Changes in the character of the faeces occurred between one and two days after inoculation and appeared to be associated with the serological response. Serological responses occurred in all the infected ponies except one. At necropsy, of the 14 ponies with positive cultures in the colon, seven had negative cultures in the rectal faeces. Serological studies performed on 43 clinically normal horses indicated a correlation between age and salmonella agglutination titre.  相似文献   

11.
Multiple drug-resistant Salmonella typhimurium, definitive type (DT) 104 and DT104b, were isolated in three separate hunting preserve bobwhite quail (Colinus virginianus) outbreaks. The cases involved 4-day-old and 3-wk-old quail with increased mortality of 5%-8.6%, respectively. Postmortem lesions included emaciation, distended abdomens, and dark colon contents, which were gaseous and fluid in consistency. Salmonella typhimurium isolated from the intestines and/or livers was resistant to ampicillin, chloramphenicol, sulfonamides, and tetracycline. The isolate involving the 3-wk-old quail was phage typed as S. typhimurium DT104. The isolates involving the two cases of 4-day-old quail were phage typed as S. typhimurium DT104b.  相似文献   

12.
Twenty-six clinically normal colostrum-fed dairy calves were allotted to 5 groups. Calves of groups 1 and 2 served as nonvaccinated controls and were challenge-exposed with variable numbers of organisms. Group-3 calves were vaccinated SC with a modified Salmonella typhimurium bacterin. The bacterin was composed of killed acid-hydrolyzed S typhimurium G30/C21 (Re-mutant) whole cells coated with alkali-hydrolyzed S typhimurium LT-2 lipopolysaccharide, as antigen, and monophosphoryl lipid A, as adjuvant. Calves of groups 4 and 5 were vaccinated with a 2% mineral oil-in-water emulsion containing lipopolysaccharide as antigen and monophosphoryl lipid A and trehalose 6-6'-dimycolate as adjuvants. Calves of groups 3-5 were vaccinated at 2 weeks of age and again at 4 or 6 weeks of age. Adverse reactions were not observed after vaccination. Calves were challenge-exposed orally at 6 or 8 weeks of age with 1.5 X 10(11) (groups 1 and 4), or 3.0 X 10(11) (groups 2, 3, and 5) colony-forming units of S typhimurium UCD 108-11. Mortality after challenge exposure was 2 of 5 group-1 calves; 4 of 5 group-2 calves; 5 of 6 group-3 calves; 1 of 5 group-4 calves; and 4 of 5 group-5 calves. Statistical difference between calves of similarly challenge-exposed groups was not evident, indicating failure of either vaccine to protect calves of this age from oral challenge exposure with virulent S typhimurium.  相似文献   

13.
Peroxidase-antiperoxidase immunoenzymatic labeling and immunogold labeling techniques were evaluated for microscopic detection and location of Salmonella organisms in tissues of experimentally infected swine. Salmonella typhimurium and Salmonella choleraesuis var kunzendorf were labeled specifically by the peroxidase-antiperoxidase technique in paraffin-embedded tissues of infected swine for conventional light microscopy and by postembedding immunogold labeling on ultrathin sections for electron microscopy. Salmonella typhimurium had a low tendency to invade the enteric mucosa and did not reveal any predilection for a specific intestinal location. Salmonella choleraesuis var kunzendorf, however, was located preferentially in colon and on the luminal surface of ileal M cells of Peyer patches and had a tendency to invade the enteric mucosa there.  相似文献   

14.
Genoa salami prepared using three different salt concentrations (2.0, 2.75 and 3.3%) were inoculated with 2.0 x 10(3) and 1.1 x 10(3) bacteria/g of Salmonella typhimurium and Staphylococcus aureus respectively. Over a period of 74 days samples were taken and analyzed for water activity and pH, counts of S. aureus and presence of Salmonella. After 11 days of dry-curing Salmonella could no longer be detected by preenrichment followed by selective enrichment procedures. Viable S. aureus were still found after 74 days of dry-curing. The results of this study would suggest that water activity and pH measurements are useful in evaluating the safety of dry-cured products.  相似文献   

15.
Groups of 25 chickens free of maternal antibody to reticuloendotheliosis virus (REV) were inoculated with either third or seventh passage REV at either one or seven days of age. Some of the birds inoculated at day 1 with REV were inoculated with Salmonella typhimurium either concurrently or six or 13 days later while some of those inoculated with REV at day 7 were inoculated concurrently with S typhimurium. At day old, infection with S typhimurium alone caused the death of 12 of 25 chicks whereas in the dual infection, using the third passage REV, 18 of 25 birds died. Similarly no seven or 14 day old chickens died when challenged with S typhimurium alone, but previous day-old infection with REV caused a respective mortality of eight of 25 and five of 25 birds. With the seventh passage REV a similar pattern was seen. At day old S typhimurium infection alone killed seven of 25 birds whereas combined with virus the mortality was 14 of 25 and while S typhimurium alone killed none of 25 chicks infected at seven days old, the mortality in birds also infected with REV was 14 of 25. Combined virus and bacterial infections did not increase the proportion of feathering defects in birds surviving S typhimurium infections. There was a significantly higher proportion of feathering defects in birds infected with third passage virus compared with seventh passage virus. Although a higher proportion of birds had antibody responses to REV in the seventh than in the third passage group, there was no discernible difference in the effect the different viruses had on chickens' susceptibility to S typhimurium.  相似文献   

16.
Experiments were conducted to establish a persistent Salmonella typhimurium infection in convalescent swine, and to determine rate of shedding and distribution of the organism in internal organs. Naturally farrowed Salmonella-free pigs (n = 37) were orally exposed to S typhimurium when 7 to 8 weeks old. Fecal samples, tonsillar scrapings, and rectal swab specimens were examined bacteriologically for S typhimurium at weekly intervals after exposure until necropsy (maximum of 28 weeks after exposure). Necropsies of 1 to 4 randomly selected pigs were conducted at 2, 4, and 7 days and at 2, 4, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. The following internal organs were examined bacteriologically for S typhimurium: liver, spleen, kidney, gallbladder, heart, lung, and stomach; segments of the intestinal tract with corresponding lymph nodes; lymph nodes from lymphocenters of the head and neck, thoracic and abdominal cavities, pelvic wall, and thoracic and pelvic limbs. Fecal samples were 83 to 100% culture-positive up to postexposure (PE) week 22, then varied from 14 to 67% positive until PE week 28. At least 60% of tonsillar swab specimens and 50% of rectal swab specimens were culture-positive up to PE week 20, after which they varied from 0 to 70% positive until PE week 28. At necropsy, S typhimurium was recovered most frequently from tonsils (93.5% positive), followed by segments of the intestinal tract from caudal portion of jejunum to rectum (71% recovery from cecum), and mandibular (54.8%) and ileocolic (45.2%) lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
A ligated intestine model in calves, pigs, and rabbits was tested for its value as an indicator of virulence of potential vaccine strains of Salmonella typhimurium. A wild virulent strain (3860C), a laboratory strain LT2, and mutants of these 2 strains were evaluated. Inoculation of calf intestinal segments with strain 3860C revealed that fluid responses were greatest in the proximal portion of the small intestine and that doses greater than 10(7) organisms were required to produce fluid responses and mucosal damage. Immunoperoxidase-stained sections of intestine revealed that a large dose of Salmonella organisms was required before mucosal invasion could be detected. Aromatic (aroA), galactose epimerase (galE), and diaminopimelic acid (dap) mutants of strain 3860C all resulted in much less fluid response, mucosal invasion, and mucosal damage compared with those by the parent organism. Strain LT2 induced such weak responses that it was not possible to evaluate reductions in virulence of its mutants. In 6-week-old pigs, there was no fluid response to any strains; however, in 1-week-old pigs, there was fluid response to the wild strain and some of its mutants. In adult rabbits, fluid responses were not observed, except when the wild strain was inoculated in the proximal portion of the small intestine. The calf and 1-week-old pig models appeared to be best suited for assessment of virulence of mutant strains of S typhimurium.  相似文献   

18.
To investigate the reason of the diarrhea in Guizhou pony,we used the feces of pony as experimental material to isolate and detect pathogenic bacteria.S6 strain was isolated from SS and XLD medium,and identified using Gram staining,biochemical tests and molecular phylogeny methods.The results showed that S6 strain could growth on SS and XLD medium,and the Gram staining was negative.Biochemical test suggested that its phenotype features were accordance with Salmonella.The 16S rRNA gene sequence of S6 strain was determined in a nucleotide sequence identity of 99% with Salmonella typhimurium ATCC 13311 (NR_119108).Based on the morphological and molecular phylogenetic results,the strain was identified as Salmonella typhimurium S6 strain.It was virulent to mice with the median lethal dose (LD50) of 4.71×102 CFU.Then,we amplified the invasion protein A (invA) gene by PCR method.The invA gene isolated from S6 strain contained 6 to 8 bp different from the known gene,which resulted in only one amino acid substitution.The mutant sites of invA gene might attribute to the pathogenicity of S6 strain.The detection rate of Salmonella was 57% in Guizhou pony population.It was inferred that the diarrhea in Guizhou pony might be caused by virulent Salmonella typhimurium.  相似文献   

19.
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.  相似文献   

20.
Twenty colostrum-fed piglets from three sows were separated from the sows 24 hours after birth and were randomly divided into five groups of four piglets each. Every piglet in each of four test groups was orally inoculated with about 10(10) colony forming units of Salmonella typhimurium, Salmonella choleraesuis var Kunzendorf or one of two isolates of Klebsiella pneumoniae. One group served as uninoculated controls. Piglets infected with K. pneumoniae developed severe diarrhea beginning about 12 hours after inoculation. They became dehydrated and weak but continued to drink. There were no morphological alterations in intestinal mucosa when piglets were killed and necropsied 48 or 72 hours after inoculation. Klebseilla pneumoniae was isolated from intestine and feces but not from liver or spleen. Piglets inoculated with S. choleraesuis became lethargic and disinterested in food by 24 hours after inoculation. Diarrhea developed by 48 hours after inoculation. Lesions at necropsy 60 or 72 hours postinoculation were subcutaneous edema, mesenteric lymphadenitis, diffuse intestinal superficial mucosal necrosis with villous atrophy, and focal deep ulceration in the ileum. Salmonella choleraesuis was isolated from all segments of intestine and from feces, liver and spleen. Piglets inoculated with S. typhimurium developed a relatively mild diarrheal disease with lesions similar to those with S. choleraesuis infection but less severe. The inoculated organism was recovered from all areas of intestine and from feces, liver and spleen. Serum from infected and control piglets had high (greater than 1:256) agglutinating titres against S. typhimurium but low titres (0 to 1:8) against S. choleraesuis. The agglutinins were assumed to originate from colostral antibodies.  相似文献   

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