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1.
Porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis are two leading causes of economic loss in the swine industry. While respiratory disease is common in both S. choleraesuis and PRRSV infections, the factors that contribute to its development remain largely undefined. We investigated the interaction of PRRSV, S. choleraesuis, and stress in 5-week-old swine. All combinations of three factors (inoculation with S. choleraesuis on Day 0, PRRSV on Day 3, and treatment with dexamethasone on Days 3-7) were used to produce eight treatment groups in two independent trials. Fecal samples, tonsil and nasal swabs, serum samples and postmortem tissues were collected for bacteriologic and virologic examinations. No clinical signs were observed in pigs inoculated with only PRRSV or only S. choleraesuis. In contrast, pigs which were dually infected with S. choleraesuis and PRRSV exhibited unthriftiness, rough hair coats, dyspnea, and diarrhea. The pigs which received all three treatment factors were the most severely affected and 43% (three of seven) of the animals in this group died. Individuals in this group shed significantly higher quantities of S. choleraesuis in feces and had significantly higher serum PRRSV titers compared to other treatments (p < or = 0.05). In addition, S. choleraesuis and PRRSV were shed longer and by more pigs in this group than other groups and S. choleraesuis was recovered from more tissues in this group on Day 21 post inoculation. These results suggested that PRRSV, S. choleraesuis, and dexamethasone acted synergistically to produce a syndrome similar to that observed in the field.  相似文献   

2.
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   

3.
Thirty five (35) rats (Rattus norvegicus) were trapped in the area of four egg producing poultry farms and were examined for Salmonella spp., micro-biologically. The samples were taken from liver, spleen and intestinal content. Cultures were made directly in MacConkey Agar, in Selenite broth and Rappaport Vassiliadis at 37 degrees C and 43 degrees C. Five strains of S. gallinarum and one strain of Salmonella subgroup II were isolated from the intestinal content of six rats. An experimental study was also carried out. Ten rats Rattus norvegicus were trapped near poultry farms of N. Greece. No Salmonella could be detected in their feces when examined three times by the Selenite 37 degrees C and Rappaport-Vassiliadis 37 degrees C methods. The rats were orally infected with an 18 hours culture of S. gallinarum (1 x 10(9)/ml microorganisms). One hundred and sixty samples of feces were periodically collected and examined for the isolation of the microorganism by the methods mentioned above. Although not any clinical sign of a disease was noticed, S. gallinarum was isolated from their feces up to 121 days post infection.  相似文献   

4.
猪霍乱沙门氏菌的快速分离鉴定   总被引：3，自引：0，他引：3  
猪霍乱沙门氏菌是引起仔猪副伤寒的主要病原菌,给养猪业造成重大危害。本文旨在建立一套细菌快速分离鉴定方法,为该病流行病学调查提供有效手段。从临床初诊为仔猪副伤寒的病猪采集粪便,接种亚硒酸盐亮绿增菌液增菌后,划线于SS琼脂培养基,挑无色透明菌落纯化。纯化菌落用美国B IOLOG自动细菌鉴定仪GN2肠杆菌鉴定板鉴定,同时用常规生化鉴定管鉴定,结果符合猪霍乱沙门氏菌的生化特征。PCR扩增invA基因,测序鉴定PCR产物,结果与猪霍乱沙门氏菌参考序列同源性达99%以上。分离菌株接种小白鼠,证明其对小白鼠有致病性。用沙门氏菌属标准血清检测证实其抗原式为6,7∶c∶1,5,符合猪霍乱沙门氏菌的抗原特征。应用以上方法从全国各地病料中分离鉴定了40多株猪霍乱沙门氏菌,为猪霍乱沙门氏菌病的流行病学调查提供了依据,同时证明该方法切实可行。  相似文献   

5.
Salmonella typhimurium infection in swine causes an enterocolitis followed by a persistent carrier state, but little is known about the mechanisms that allow this organism to colonize and persist in host tissues. Neutrophils provide a first line of defense against invading pathogens such as Salmonella typhimurium. The purpose of this study was to evaluate porcine neutrophil function after in vivo exposure to Salmonella and to determine if the immunomodulator, bacillus Calmette Guerin (BCG), exerts any effect on neutrophil function or on the colonization and persistence of S. typhimurium in the pig. Compared to negative controls, neutrophils from pigs exposed to S. typhimurium exhibited significantly decreased iodination, cytochrome-C reduction, antibody-dependent cell-mediated cytotoxicity, random migration, and chemotaxis (P less than or equal to 0.05). Neutrophil bactericidal activity against S. typhimurium was significantly enhanced. Most of the significant differences were noted in the first two days after exposure to Salmonella. Often the functional alterations were biphasic, peaking again 7-10 days after exposure. BCG alone significantly depressed random migration and cytochrome-C reduction in unstimulated neutrophils. The clinical course, colonization pattern, and persistence of Salmonella were similar between pigs receiving BCG and untreated pigs. These data suggest that S. typhimurium infection causes a depression in oxidative metabolism and motility, yet an increase in overall bactericidal activity against S. typhimurium in circulating porcine neutrophils. It also appears that BCG treatment, as reported here, does not enhance resistance of pigs to S. typhimurium colonization or reduce the number of persistent organisms in the porcine ileum.  相似文献   

6.
Salmonella choleraesuis strain 38 (glycerol-positive fermentation) was repeatedly exposed to porcine neutrophils in an attempt to mimic in vivo conditions of the host immune system. After phagocytosis, viable intracellular S choleraesuis were isolated and the process was repeated at least 5 times. A fifth-passage strain-38 neutrophil-adapted clone, 38PMNa-5X, was isolated, and was compared with the parent wild-type strain 38 for changes. Strain 38PMNa-5X had increased resistance to killing by hydrogen peroxide and phagocyte killing by porcine neutrophils, as measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction. Strain 38PMNa-5X was less invasive than the parent strain on Vero cell monolayers, and had been cured of a 50-kb plasmid. The 50-kb plasmid was marked with bacteriophage mini-Mu (kanamycin resistant) and was reinserted into strain 38PMNa-5X. Strain 38PMNa-5X was avirulent in mice, but the isolates with reinserted plasmids had intermediate resistance to neutrophil and hydrogen peroxide killing and had restored invasiveness and mouse virulence. Differences in complement sensitivity and enzymatic activity were not observed between the strains.  相似文献   

7.
A study was conducted to examine sources of variation introduced into a phagocytosis assay as a result of the isolation of neutrophils from bovine blood, including variation attributable to isolation of neutrophils from blood, variation between duplicate determinations of percentage phagocytosis, and the variation in the ability of neutrophils isolated from blood (over repeated collections from the jugular vein) to phagocytose. For the phagocytosis assay, jugular venous blood from each of 4 cows was divided into 2 equal portions. The neutrophils were isolated by lysis of red blood cells with 0.2% sodium chloride. The neutrophils (2 x 10(7)) were incubated in duplicate with 32P-labeled Staphylococcus aureus ([32P]SA; 2 x 10(8)) in skimmed milk samples (2.5% final concentration) prepared from 4 cows. This process was repeated thrice on neutrophils isolated from 4 cows at 2-week intervals. The proportions of variation in percentage of 32P-labeled S aureus phagocytosed between duplicate neutrophil isolations and between duplicate assay determinations were 0 and 1%. Differences among skimmed milk sources and among runs, using blood neutrophils taken at different times from the same donor cow, accounted for 62 and 36% of the total variation. The results indicated that variation arising from blood neutrophil isolation introduced into a phagocytosis assay within a single-day trial is of no concern. The large variation among skimmed milk sample sources indicated differences among cows in the ability of their milk to support phagocytosis. The variation in neutrophil isolations over time for any cow was considered too large to allow for evaluation of physiologic and environmental effects on phagocytosis of neutrophils isolated from blood.  相似文献   

8.
本研究通过采用高通量测序、平板筛选、16S rDNA序列分析、特异性碳源培养和牛津杯法,从哺乳期健康仔猪的粪便中筛选分离和鉴定乳杆菌,并进行其利用表乳糖生长特性以及抑制仔猪腹泻相关致病菌活性的试验研究,探索表乳糖定向调控仔猪肠道乳杆菌增殖的可能性。结果表明:从7~10日龄哺乳期健康仔猪的粪便样品中分离出9株乳杆菌,其中唾液乳杆菌、卷曲乳杆菌、淀粉乳杆菌具有较强利用表乳糖的能力,在以2%表乳糖为唯一碳源的MRS培养基中显现出良好的生长态势,而且其培养上清液对大肠杆菌(猪源)、猪霍乱沙门氏菌、单核细胞增生李斯特氏菌、宋氏志贺氏菌以及金黄色葡萄球菌具有较好的抑菌活性。  相似文献   

9.
The growth of Salmonella Choleraesuis was examined in Rappaport Vassiliadis broth (RV) and Hajna-tetrathionate broth (HTT) at 37 and 42 degrees C. As the enrichment in RV at 37 degrees C was satisfactory for isolating S. Choleraesuis, we used this enrichment for isolation from the samples collected from 15 asymptomatic pigs reared on a S. Choleraesuis contaminated farm. S. Choleraesuis was frequently isolated from six pigs (40.0%) under field conditions. The isolation of other Salmonella serovars than S. Choleraesuis was attempted by using both RV enrichment at 37 degrees C and HTT enrichment at 42 degrees C. Salmonella organisms were isolated from 156 (44.8%) of 348 fecal samples and more frequently with HTT at 42 degrees C (43.4%) than with RV at 37 degrees C (20.9%). If other serovars in addition to S. Choleraesuis are to be surveyed, HTT enrichment should be used in combination with RV enrichment.  相似文献   

10.
A total of 1,013 feces samples and 8 mesenteric lymphonodus samples obtained from apparently healthy dogs were examined for the incidence of salmonella infection. One strain of S. typhimurium (ST) was isolated from feces of one dog, and S. enteritidis (SE) was isolated from the mesenteric lymphonodus of one dog. Sera obtained from 330 apparently healthy dogs were examined for Salmonella antibodies using an ELISA with heated whole cells of SE and ST. Fifty-one of the 330 serum samples were considered to be positive for salmonella antibodies, including 12 which were SE-positive and 39 which were ST-positive. These results indicate that dogs cause possible environmental problems as Salmonella carriers.  相似文献   

11.
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   

12.
Long-term survival and infectivity of Salmonella choleraesuis   总被引：1，自引：0，他引：1  
It is believed that Salmonella Choleraesuis, the host-adapted serotype of swine, does not survive well outside the host. We examined the survival capability as well as the presence of latent DNA of S. Choleraesuis in swine feces. Pigs were infected with S. Choleraesuis and feces was collected and pooled on days 2, 4, 7, and 10 post inoculation (PI). Feces was stored in a wet and a dry form and survival was measured over 13 months. Salmonella Choleraesuis was recovered from wet feces through 3 months of storage. In a desiccated (dry) form, S. Choleraesuis was recovered from at least 13 months. Direct PCR analysis did not detect S. Choleraesuis subsequent to the final culture recovery for any stored sample. We also examined the infectivity of S. Choleraesuis resident in dry feces. Six or 13 week old pigs were inoculated with dry feces that had been stored either 2 months or 4 months, respectively. Pigs were inoculated either intranasally or by mixing dry feces with the swine ration. Although clinical signs were mild, S. Choleraesuis was widely disseminated among the tissues of all the pigs inoculated. This study demonstrates that S. Choleraesuis remains viable and infective in the environment. Therefore, contaminated fecal matter can serve as a reservoir for S. Choleraesuis as well as other Salmonella spp. Control measures must consider this environmental reservoir as a source of new infections.  相似文献   

13.
A glucose analog, 2-deoxy-d-glucose (2DG), previously shown in swine to induce many of the hallmark parameters of stress, was administered to Salmonella choleraesuis carrier-swine and the effects on Salmonella fecal shedding and tissue colonization were evaluated. Initially, pigs were divided into two groups, one that received 1 x 10 (6) S. choleraesuis and one group that received saline. At 3 or 6 weeks post inoculation (PI), half of each group received an injection of 2DG and the other half received saline. Throughout the study, individual fecal samples were collected and quantitatively cultured for Salmonella, tonsil and nasal swabs were qualitatively cultured, clinical signs were monitored, temperatures were measured and whole blood collected. Pigs were necropsied 8-18 days after 2DG treatment. The experimental stress induced by 2DG was not sufficient to cause recrudescence of Salmonella fecal shedding even when tissues were culture positive for Salmonella. In addition, persistent shedding was not affected by 2DG administration. Although the complex set of parameters that constitute the stress phenomenon is still relatively unknown, it is now apparent that the stressful event(s) sufficient to trigger Salmonella recrudescence involves more than just increased blood glucose, increased cortisol, and inhibition of lymphocyte proliferation.  相似文献   

14.
Approximately 200 opossums, trapped during the fall of 1973 in the vicinity of Raleigh, NC, were maintained in the Institute's breeding colony in individual cages until the breeding season. Clinically normal, dead, and moribund opossums were examined for Salmonella. Six serotypes of Salmonella were identified in both clinically normal and diseased opossums. Positive culture results were obtained on 39 of 56 (70%) rectal swab specimens collected in the fall from incoming opossums, and on 30 of 50 (60%) rectal swab specimens collected during midwinter from an additional group of clinically normal opossums, which were maintained in isolation for approximately 3 months before testing. At necropsy, 87 of 108 (81%) diseased opossums were culture positive for Salmonella. Salmonellae in serogroups B and R were isolated from the spleen, liver, kidneys, or heart blood as well as the ileum of 57 diseased opossums. In 23 cases, S typhimurium or S bern was isolated in pure culture from the visceral organs. These findings indicated bacterial septicemia. In contrast, salmonellae in serogroups C1, E1, and F were routinely isolated from the feces of clinically normal and diseased opossums, suggesting a habitat restricted to the intestinal tract and probably the mesenteric lymph nodes. It was concluded that the opossum serves as a reservoir for a number of serotypes of Salmonella and may have an important role in the epizootiology of wildlife salmonellosis.  相似文献   

15.
Weaned pigs were immunised with a live attenuated Salmonella choleraesuis vaccine. The protective immunity induced was compared with that of unvaccinated pigs by intranasal challenge with a field strain of S choleraesuis. Of 18 unvaccinated pigs, three died as a result of challenge from S choleraesuis and 10 of the survivors developed chronic lung lesions. None of the vaccinated pigs died as a result of challenge and two only showed macroscopic evidence of salmonellosis on autopsy three weeks after challenge. It was concluded that subcutaneous vaccination of pigs prevented death and clinical illness but did not prevent invasion of tissues following intranasal challenge with S choleraesuis.  相似文献   

16.
In order to determine the prevalence of Salmonella spp. in domestic animals in 6 provinces of the Mekong Delta, Vietnam, 1,098 fecal or intestinal content samples from pigs, chickens, and ducks were examined in the period from July to October, 2000. Salmonella spp. were isolated from 78 (7.1%) of the total samples, which included 23 (5.2%) of 439 pigs, 24 (7.9%) of 302 chickens, and 31 (8.7%) of 357 ducks. From those samples, 80 Salmonella strains were isolated and 25 serovars were identified. The predominant serovars were S. Javiana, S. Derby, and S. Weltevreden. S. Javiana and S. Weltevreden were detected together in pigs, chickens, and ducks. These results indicate that the serovars of Salmonella are widely distributed in domestic animals in the Mekong Delta, Vietnam.  相似文献   

17.
The effect of different fecal sample weights on the detection of Salmonella enterica in swine feces was examined. Sample weights evaluated were rectal swabs and fecal samples weighing 1 g, 10 g, and 25 g. Comparisons were made on matched fecal samples obtained from individual pigs housed on 2 commercial swine farms in North Carolina. Relative sensitivity (number of positive pigs per fecal weight category/number positive in all weight categories) increased (P < 0.001) with fecal sample weight, and ranged from 9% for rectal swabs to 78% for 25-g samples. Stomaching of fecal samples did not affect detection of S. enterica. These observations demonstrate that fecal sample weight can markedly influence estimates of prevalence of S. enterica in epidemiologic studies. Failure to consider the imperfect sensitivity of bacterial culture in the design and interpretation of epidemiologic studies will lead to underestimation of prevalence and reduced power to detect the presence of S. enterica-infected herds.  相似文献   

18.
The effect of organic acids and mannanoligosaccharide addition to the diet was assessed in pigs orally inoculated with Salmonella typhimurium. Forty-six growers were distributed among four treatments: Basal Diet (BD); BD+encapsulated organic acids; BD+free organic acids; BD+mannanoligosaccharide. Seroconversion was monitored, and feces and tissue samples were tested for Salmonella isolation. No treatment prevented the carrier state, but a tendency of lower fecal excretion was observed in the group treated with mannanoligosaccharide.  相似文献   

19.
In the United States, swine salmonellosis is most often attributed to infections by Salmonella serovar choleraesuis. As a host-adapted pathogen rarely found in nonswine sources, S. choleraesuis is thought to be spread primarily via horizontal transmission, with carrier animals playing an important role. Little has been reported regarding infection of neonatal piglets, particularly regarding their potential to become carriers. Evidence reported herein demonstrates that piglets experimentally infected by S. choleraesuis at 2 days of age were capable of shedding the pathogen for up to 85 days postinfection, at which time the study was concluded. This study also presents findings supporting the use of GN-Hajna as a preenrichment medium for the isolation of S. choleraesuis.  相似文献   

20.
Feces collected from 40 horses with diarrhea and 34 horses without diarrhea were examined to determine if an association existed between isolation of Aeromonas spp. and diarrhea. Samples were also examined for Salmonella spp., and identification of viruses and parasite ova. Neither Salmonella spp. nor Aeromonas spp. were isolated from the feces of 34 control horses. Aeromonas spp. were isolated from feces of 22 of 40 (55%) horses with diarrhea. Salmonella spp. were isolated from feces of 8 (20%) horses, and of these, 5 (12.5%) were also positive for Aeromonas spp. Twenty-nine isolates of Aeromonas spp. were recovered from the feces of 22 diarrheic horses. Of these isolates, more than 80% were susceptible on in vitro testing to amikacin, ceftiofur, chloramphenicol, and gentamicin. All isolates were susceptible to enrofloxacin. Diarrheic horses positive for Aeromonas were significantly (P = .04) older than diarrheic horses negative for Aeromonas spp. A significantly greater number of fecal samples were positive for Aeromonas spp. during March through August than samples examined in other months (P = .014). Results of this study indicate that Aeromonas spp. should be considered as a cause of diarrhea in horses.  相似文献   

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