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  • Author or Editor: Paula J. Fedorka-Cray x
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Abstract

Objective

To establish the effect of dose on persistence of and immune response to Salmonella choleraesuis in swine.

Design

19 Salmonella-free pigs were allotted to 4 groups. Groups 1 (n = 5), 2 (n = 5), and 3 (n = 5) were inoculated intranasally with 109, 106, and 103 colony-forming units of S choleraesuis, respectively. Group 4 (n = 4) served as uninoculated controls.

Procedure

Pigs were monitored for clinical signs of disease and bacterial shedding. Serum and lymphocytes were obtained to measure immune responses. Pigs from groups 1, 2, and 4 were necropsied at postinoculation (PI) weeks 6 and 15. Pigs from groups 3 and 4 were necropsied at PI weeks 6 and 10.

Results

Pigs in group 1 shed S choleraesuis through PI week 15 and were tissue positive at PI weeks 6 and 15. Pigs in group 2 were tissue positive for S choleraesuis until PI week 6 and continued shedding through PI week 9. Salmonella choleraesuis was not recovered at any time from pigs in groups 3 or 4. Pigs in groups 1, 2, and 3 had serum IgG and IgM titers to S choleraesuis lipopolysaccharide and soluble antigens. Pigs in all groups had a lymphocyte response to concanavalin A, and pigs in groups 1 and 2 had a lymphocyte response to S choleraesuis endotoxin. Pigs in group 1 had a lower stimulation index in response to both antigens, indicating some form of lymphocyte immunosuppression.

Conclusions

Persistence of S choleraesuis in host tissues is dose dependent. Short-term persistence can occur after a dose as low as 106 colony-forming units of S choleraesuis. Higher doses result in development of longterm carrier status, which may be related to the observed lymphocyte immunosuppression.(Am J Vet Res 1996;57:313-319)

Free access
in American Journal of Veterinary Research

SUMMARY

A series of experiments was conducted to document tumor necrosis factor-α (tnf) activity in serum of swine after inoculation with Salmonella spp endotoxin and after oral or respiratory tract challenge exposure with live Salmonella spp. For experiment 1, a potentially lethal dose of S typhimurium endotoxin (25 μg/kg of body weight) was administered iv, and serum tnf activity was measured. High tnf (approx 700 IU/ml) activity at 1 to 2 hours after administration of the inoculum was associated with death, whereas lower tnf (approx 30 IU/ml) activity was associated with a general prolonged state of shock. For experiment 2, pigs were administered a nonlethal dose (5 μg/kg, iv) of either S typhimurium or S choleraesuis endotoxin. Difference in the ability to induce porcine serum tnf activity was not observed between strains. During experiment 3, pigs were inoculated with 104 colony-forming units of S typhimurium χ4232 either orally by gelatin capsule (gc) or by intranasal (in) instillation. A late serum tnf response (17 IU/ml) was measured at 6 weeks after in inoculation. A serum tnf response was not detected in gc-inoculated pigs. All tissues and feces were test-negative for S typhimurium prior to the 6-week tnf response. Serum tnf activity may be related to clearance of S typhimurium after respiratory tract exposure, but it is not important to or indicative of clearance of orally presented S typhimurium in swine. During experiment 4, pigs were inoculated with 106 colony-forming units of S typhimurium χ4232 similarly as for experiment 3. Challenge exposure with this medium-size dose of inoculum induced a prolonged peak serum tnf response (37 IU/ml) between 2 and 4 weeks after in inoculation. Again, serum tnf activity was not detected in gc-inoculated pigs. Data suggest that clearance of a medium-size dose (106) of inoculum may be influenced by the prolonged higher serum tnf activity. For experiments 5 and 6, pigs were inoculated in with 103, 106, 108, or 109 S choleraesuis χ3246. A measurable, yet statistically nonsignificant, serum tnf response was observed for all doses. Pigs inoculated by gc with 108 S choleraesuis χ3246 had similar results. High doses (> 106) of live S choleraesuis were associated with clinical signs of endotoxic shock. Clearance of S choleraesuis, or lack thereof, did not correlate with serum tnf activity.

Free access
in American Journal of Veterinary Research

Summary

Clinical trials have shown that currently available commercial vaccines against porcine pleuropneumonia provide inconsistent, serotype-specific protection from the disease. Recovery from naturally acquired infection, however, provides solid, serotype cross-protective immunity. We examined various serum responses of pigs receiving 1 of 4 commercial vaccines or a cell extract, and compared the serologic responses of these pigs after challenge exposure with virulent Actinobacillus pleuropneumoniae serotype 1. Evaluation of serum included complement-mediated killing, opsonizing capacity, IgG titers to whole organisms, and cytotoxin neutralization titers. Pigs that received the cell extract had fewer clinical signs of pleuropneumonia than pigs in other vaccinated groups, and also were significantly (P< 0.05) better protected from development of lung lesions and death. Such vaccinates were the only pigs that developed significant (P< 0.05) serum antibody titers (ie, protective immune response) to whole-cell antigens and to cytotoxin.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To investigate Salmonella enterica infections at a Greyhound breeding facility.

Design—Cross-sectional study.

Animal and Sample Populations—138 adult and juvenile dogs and S enterica isolates recovered from the dogs and their environment.

Procedures—The investigation was conducted at the request of a Greyhound breeder. Observations regarding the environment and population of dogs were recorded. Fecal, food, and environmental specimens were collected and submitted for Salmonellaculture. Isolates were serotyped and tested for susceptibility to 16 antimicrobials. Isolates underwent genetic analyses by use of pulsed-field gel electrophoresis and ribotyping.

Results—S enterica was recovered from 88 of 133 (66%) samples of all types and from 57 of 61 (93%) fecal samples. Eighty-three (94.3%) of the isolates were serotype Newport, 77 (87.5%) of which had identical resistance phenotypes. Genetic evaluations suggested that several strains of S enterica existed at the facility, but there was a high degree of relatedness among many of the Newport isolates. Multiple strains of Salmonella enterica serotype Newport were recovered from raw meat fed on 1 day.

Conclusions and Clinical RelevanceS enterica infections and environmental contamination were common at this facility. A portion of the Salmonellastrains detected on the premises was likely introduced via raw meat that was the primary dietary constituent. Some strains appeared to be widely disseminated in the population. Feeding meat that had not been cooked properly, particularly meat classified as unfit for human consumption, likely contributed to the infections in these dogs.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the antimicrobial susceptibility patterns of Salmonella isolates from feedlot cattle.

Design—Cross-sectional study.

Sample Population—263 Salmonella isolates.

Procedures—Fecal samples were collected from the floor of 2 pens in each of 100 feedlots. Two hundred eighty Salmonella isolates were recovered after bacteriologic culture from 38 pens. Of these, 263 isolates were available for antimicrobial susceptibility testing to 16 antimicrobials, using microbroth dilution breakpoint plates.

Results—Less than 5% of isolates were resistant to any of the antimicrobials tested, with the exception of sulfamethoxazole (15; 5.7%) and tetracycline (61; 23.2%). Most isolates (197; 74.9%) were susceptible to all antimicrobials tested, whereas 18 (6.8%) were resistant to 2 or more antimicrobials. The percentage of isolates with resistance to any antimicrobial varied by serotype. The percentage of isolates resistant to various antimicrobials was not related to concurrent use of antimicrobials in the feed.

Conclusions and Clinical Relevance—With the exception of tetracycline and sulfamethoxazole, resistance of Salmonella isolates to any of the antimicrobials was uncommon. Most isolates were susceptible to all antimicrobials tested. Antimicrobial resistance was not related to the presence of antimicrobials in the ration being fed at the time of sample collection. (J Am Vet Med Assoc 2002;221:268–272)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To estimate prevalence of fecal shedding of Salmonella spp among horses in the US horse population and prevalence of Salmonella spp in grain or other concentrate used as horse feed on equine operations in the United States.

Design—Cross-sectional survey.

Sample Population—Horses on 972 operations in 28 states.

Procedure—Fecal samples were collected from horses resident at each operation. Only a single sample was collected from any individual horse; number of horses from which samples were collected on each operation was determined on the basis of number of horses on the operation. A single sample of grain or concentrate was also collected from each operation. All samples were tested for Salmonella spp by means of bacterial culture.

Results—Overall, 0.8% (SE, 0.5) of resident horses shed Salmonella spp in their feces. The overall prevalence of operations positive for fecal shedding of Salmonella spp (ie, operations with ≥ 1 horse shedding Salmonella spp in its feces) was 1.8% (SE, 0.7). Prevalence of grain or other concentrate samples positive for Salmonella spp was 0.4%. Serotypes of Salmonella spp that were identified in grain or other concentrate were not those typically associated with clinical disease in horses.

Conclusions and Clinical Relevance—Results suggest that the national prevalence of fecal shedding of Salmonella spp by horses in the United States was 0.8%, and that prevalence of Salmonella spp in grain or other concentrate used for horse feed was 0.4%.(J Am Vet Med Assoc 2000;217:226–230)

Full access
in Journal of the American Veterinary Medical Association

Objective

To compare prevalence of fecal shedding of Salmonella organisms and serum antibodies to Salmonella sp in market-age pigs housed in barns with partially slotted floors or solid floors with openflush gutters.

Design

Cross-sectional study of prevalence.

Sample Population

Finishing-age pigs deemed by the producer to be within 1 month of slaughter.

Procedure

Fecal and serum samples were obtained from a group of 121 pigs housed in a barn with solid floors (31 fecal samples, 30 serum samples) and from a group of about 400 pigs housed on partially slotted floors (57 fecal samples, 64 serum samples). Fecal samples were submitted for bacteriologic culture to detect Salmonella organisms, and serum samples were tested for antibodies by use of ELISA.

Results

Salmonella agona was isolated from 26 of 31 (84%) fecal samples obtained from pigs housed in the open-flush gutter barn, compared with 5 of 57 (9%) fecal samples from pigs in the barn with slotted floors. Median value for optical density was higher for serum samples from pigs housed in the openflush gutter barn.

Clinical Implications

Housing of finishing-age swine in barns with open-flush gutters may contribute to increased shedding of Salmonella sp. Analysis of our observations indicated that repeated exposure to infected feces is important in prolonging fecal shedding by swine. (J Am Vet Med Assoc 1997;210:386–389

Free access
in Journal of the American Veterinary Medical Association

Objective

To test feed and feed ingredients on swine farms for Salmonella organisms and to analyze data from these farms to determine risk factors associated with Salmonella organisms in the feed and feed ingredients.

Design

Epidemiologic survey and retrospective case-control study.

Sample Population

30 swine farms.

Procedure

Samples of feed and feed ingredients and information regarding herd characteristics were collected from 30 swine farms. Samples were tested for Salmonella organisms, and data compiled from herd information forms were examined for associated risk factors between herd characteristics and isolation of Salmonella organisms.

Results

Salmonella organisms were isolated from 36 of 1,264 (2.8%) feed and feed ingredient samples and from 14 of 30 (46.7%) farms. Thirteen Salmonella sp serotypes and 2 untypeable isolates were cultured. Recovery of Salmonella organisms from at least 1 feed or feed ingredient on a farm was significantly associated with 6 herd characteristics (lack of bird-proofing, using farm-prepared feed for finishing-age pigs rather than purchased feed, and housing pigs in facilities other than total confinement in the growing, finishing, gestating, and breeding stages of production, respectively). Isolation of Salmonella sp was not associated with a history of salmonellosis on a farm.

Clinical Implications

Salmonella organisms were readily isolated from samples of feed and feed ingredients, illustrating that salmonellae are ubiquitous in a farm environment. Implementing sanitary and pestcontrol measures continues to be a prudent recommendation. Salmonella serotypes found in feed and feed ingredients have the potential to cause disease in pigs that consume the feed or, ultimately, in people that consume pork. (J Am Vet Med Assoc 1997;210: 382–385

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To test the association between exposure to bovine coronavirus (BCV) and outbreaks of winter dysentery (WD) in dairy herds and to examine other risk factors for outbreaks of WD in dairy herds.

Animals

12 dairy herds in Ohio affected with WD (case herds). For each case herd, 2 unaffected herds from the same area were concurrently used as control herds.

Procedure

A case-control study was conducted, using herds as the unit of investigation. Multivariate logistic regression modeling was used to identify risk factors for contracting disease.

Results

4 factors appeared to increase a herd's risk for WD: increase in herd prevalence of adult cows that had a fourfold or more increase in BCV serum IgG antibody titer; increase in herd prevalence of adult cows that had a fourfold or more increase in bovine viral diarrhea virus (BVDV) titer; housing cattle in tie-stall or stanchion barns rather than free-stall facilities; and use of equipment to handle manure and subsequently handle feed. The adjusted population-attributable risk for these variables was 71, 43, 53, and 31%, respectively, and 99% overall, indicating that these variables had considerable impact on WD outbreaks for the study population.

Conclusions and Clinical Relevance

In dairies in Ohio, recent herd exposure to BCV appeared to increase the risk for WD outbreaks. Some WD outbreaks might have been associated with acute BVDV infection. Certain housing and management practices may have increased the risk of an outbreak of WD. (Am J Vet Res 1998;59:994–1001)

Free access
in American Journal of Veterinary Research