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Abstract

Objective—To evaluate antimicrobial susceptibility of commensal Escherichia coli strains isolated from the feces of horses and investigate relationships with hospitalization and antimicrobial drug (AMD) administration.

Design—Observational study.

Animals—68 hospitalized horses that had been treated with AMDs for at least 3 days (HOSP–AMD group), 63 hospitalized horses that had not received AMDs for at least 4 days (HOSP–NOAMD group), and 85 healthy horses that had not been hospitalized or treated with AMDs (community group).

Procedures—Fecal samples were submitted for bacterial culture, and up to 3 E coli colonies were recovered from each sample. Antimicrobial susceptibility of 724 isolates was evaluated. Prevalence of resistance was compared among groups by use of log-linear modeling.

Results—For 12 of the 15 AMDs evaluated, prevalence of antimicrobial resistance differed significantly among groups, with prevalence being highest among isolates from the HOSP–AMD group and lowest among isolates from the community group. Isolates recovered from the HOSP–AMD and HOSP–NOAMD groups were also significantly more likely to be resistant to multiple AMDs. Resistance to sulfamethoxazole and resistance to trimethoprim-sulfamethoxazole were most common, followed by resistance to gentamicin and resistance to tetracycline. Use of a potentiated sulfonamide, aminoglycosides, cephalosporins, or metronidazole was positively associated with resistance to 1 or more AMDs, but use of penicillins was not associated with increased risk of resistance to AMDs.

Conclusion and Clinical Relevance—Results suggest that both hospitalization and AMD administration were associated with prevalence of antimicrobial resistance among E coli strains isolated from the feces of horses.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate effectiveness of 4% peroxymonosulfate disinfectant applied as a mist to surfaces in a large animal hospital as measured by recovery of Staphylococcus aureus and Salmonella enterica serovar Typhimurium.

Design—Field trial.

Sample Population—Polyester transparencies inoculated with bacteria.

Procedure—Polyester transparencies were inoculated with S aureus or S Typhimurium and placed in various locations in the hospital. After mist application of the peroxygen disinfectant, viable bacterial numbers were quantified and compared with growth from control transparencies to assess reduction in bacterial count.

Results—When applied as a mist directed at environmental surfaces contaminated with a geometric mean of 4.03 × 107 CFUs of S aureus (95% confidence interval [CI], 3.95 × 107 to 4.11 × 107) or 6.17 × 106 CFUs of S Typhimurium (95% CI, 5.55 × 106 to 6.86 × 106), 4% peroxymonosulfate reduced the geometric mean number of viable S aureus by 3.04 × 107 CFUs (95% CI, 8.6 × 105 to 1.7 × 106) and S Typhimurium by 3.97 × 106 CFUs (95% CI, 8.6 × 105 to 3.5 × 106).

Conclusions and Clinical Relevance—Environmental disinfection with directed mist application of a 4% peroxymonosulfate solution was successful in reducing counts of bacterial CFUs by > 99.9999%. Directed mist application with this peroxygen disinfectant as evaluated in this study appeared to be an effective and efficient means of environmental disinfection in a large animal veterinary hospital and would be less disruptive than more traditional approaches to intensive environmental cleaning and disinfection. (J Am Vet Med Assoc 2005;227:597–602)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify factors associated with development of vesicular stomatitis (VS).

Design—Case-control study.

Sample Population—138 livestock premises and 118 horses suspected of having VS in Texas, New Mexico, and Colorado.

Procedures—Premises with ≥ 1 animal with clinical signs and laboratory confirmation of infection were classified as case premises. Premises where laboratory confirmation results were negative were control premises. Among equine premises, case and control horses were selected on the basis of premises status. A survey was conducted to identify factors associated with VS for premises and specific horses.

Results—Control of insect populations in the 2 weeks before the VS investigation decreased the odds of disease for premises where vegetation coverage was grassland or pasture (odds ratio [OR], 0.08; 95% confidence interval [CI], 0.01 to 0.7). Odds of VS for premises covered with grassland or pasture increased when measures to control insect populations were not used (OR, 11; 95% CI, 0.8 to 156.3) and for premises that had a body of water (OR, 2.3; 95% CI, 1.0 to 5.6). Use of measures to prevent insect bites or harassment by insects (OR, 0.2; 95% CI, 0.1 to 0.8) and spending time in shelters (OR, 0.4; 95% CI, 0.2 to 1.1) in the 2 weeks prior to investigation decreased the odds of being a case horse.

Conclusions and Clinical Relevance—Insect control and spending time in shelters decreased the odds for infection with VS. Premises covered with grassland or pasture or that had a body of water were at a higher risk.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify risk factors associated with respiratory tract disease in horses during 3 epidemics caused by influenza virus infections.

Design—Cross-sectional and prospective longitudinal observational studies.

Animals—1,163 horses stabled at a Thoroughbred racetrack.

Procedure—Investigations were conducted during a 3-year period. An epidemic of respiratory tract disease caused by influenza virus infections was identified in each year. Routine observations and physical examinations were used to classify horses' disease status. Data were analyzed to identify factors associated with development of disease.

Results—Results were quite similar among the epidemics. Concentrations of serum antibodies against influenza virus and age were strongly associated with risk of disease; young horses and those with low antibody concentrations had the highest risk of disease. Calculation of population attributable fractions suggested that respiratory tract disease would have been prevented in 25% of affected horses if all horses had high serum antibody concentrations prior to exposure. However, recent history of vaccination was not associated with reduction in disease risk. Exercise ponies had greater risk of disease than racehorses, which was likely attributable to frequent horse-to-horse contact.

Conclusion and Clinical Relevance—Particular attention should be paid to young horses, those with low serum antibody concentrations, and horses that have frequent contact with other horses when designing and implementing control programs for respiratory tract disease caused by influenza virus infections. It appears that control programs should not rely on the efficacy of commercial vaccines to substantially reduce the risk of disease caused by influenza virus infections. (J Am Vet Med Assoc 2000;216:545–550)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To develop a syndromic surveillance system based on visual inspection from outside the livestock pens that could be used for detection of disease among livestock entering an auction market.

Design—Cross-sectional study.

Animals—All livestock (beef and dairy cattle, sheep, goats, horses, and pigs) entering a single auction market in Colorado during 30 business days.

Procedures—Livestock were enumerated and visually inspected for clinical signs of disease by a veterinarian outside the pens, and clinical signs that were observed were categorized into 12 disease syndromes. Frequency of clinical signs and disease syndromes was then calculated.

Results—Data were recorded for a total of 29,371 animal observation days. For all species combined, the most common disease syndrome was respiratory tract disease (218.9 observations/10,000 animal observation days), followed by thin body condition and abnormal ambulation or posture (80.7 and 27.2 observations/10,000 animal observation days, respectively). Together, these 3 disease syndromes accounted for 92.8% of all clinical signs of disease observed. The syndromes least commonly identified were non–injury-related hemorrhage, death, and injury-related hemorrhage (0.0, 0.3, and 0.7 observations/10,000 animal observation days, respectively).

Conclusions and Clinical Relevance—Results suggested that a syndromic surveillance system based on visual inspection alone could be developed to identify possible disease conditions among livestock at an auction market. Further studies are needed to determine the sensitivity and specificity of visual observation in detecting disease.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To assess production animal medicine veterinarians' prescription practices and identify factors influencing their use of antimicrobial drugs (AMDs) and their perceptions of and attitudes toward antimicrobial resistance (AMR).

SAMPLE

157 production animal veterinarians in the United States.

PROCEDURES

An online cross-sectional survey and digital diary were used to gather information regarding perceptions on AMD use and AMR and on treatment recommendations for production setting-specific disease scenarios. Results were compared across respondents grouped by their selected production setting scenarios and reported years as veterinarians.

RESULTS

The most commonly selected production setting disease scenarios were dairy cattle (96/157 [61.1%]), backgrounding cattle (32/157 [20.4%]), and feedlot cattle (20/157 [12.7%]). Because few respondents selected swine (5/157 [3.2%]) or poultry (4/157 [2.5%]) scenarios, those responses were excluded from statistical analysis of AMD prescription practices. Most remaining respondents (147/148 [99.3%]) reported that they would recommend AMD treatment for an individual ill animal; however, responses differed for respondents grouped by their selected production setting scenarios and reported years as veterinarians when asked about AMD treatment of an exposed group or high-risk disease-free group. Most respondents reported that government regulations influenced their AMD prescribing, that owner and producer compliance was a veterinary-related factor that contributed to AMR, and that environmental modifications to prevent disease could be effective to mitigate AMR.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of the present study helped fill important knowledge gaps pertaining to prescription practices and influencing factors for AMD use in production animal medicine and provided baseline information for future assessments. This information could be used to inform future interventions and training tools to mitigate the public health threat of AMR.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate factors potentially associated with fecal Salmonella shedding among equine patients hospitalized for colic at a veterinary teaching hospital and to determine the effects of probiotic treatment on fecal Salmonella shedding and clinical signs.

Design—Longitudinal study and controlled trial.

Animals—246 equine colic patients.

Procedure—History and medical information were obtained from patient records. Fecal and environmental samples were submitted for aerobic bacterial culture for Salmonella enterica. Fifty-one patients were treated with a commercially available probiotic; 46 were treated with a placebo. Logistic regression was used to evaluate data.

ResultsSalmonella organisms were detected in feces from 23 (9%) patients at least once during hospitalization. Patients were more likely to shed Salmonella organisms if diarrhea was evident ≤ 6 hours after hospitalization and duration of hospitalization exceeded 8 days (odds ratio [OR], 20.3), laminitis developed during hospitalization (OR, 12.0), results of nasogastric intubation were abnormal (OR, 4.9), leukopenia was evident ≤ 6 hours after hospitalization (OR, 4.6), or travel time to the teaching hospital exceeded 1 hour (OR, 3.5). Horses treated with the probiotic did not differ from control horses in regard to likelihood of fecal Salmonella shedding (OR, 1.5) or prevalence of clinical signs.

Conclusions and Clinical Relevance—Results suggest that certain risk factors are associated with fecal shedding of S enterica among equine patients hospitalized at a veterinary teaching hospital because of colic and that pathogen monitoring in patients and the hospital environment and use of barrier nursing precautions for equine colic patients are beneficial. (J Am Vet Med Assoc 2001;218:740–748)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the efficacy of a peroxygenbased disinfectant used in footbaths with the efficacy of the same disinfectant used in footmats for reducing bacterial contamination of footwear in a large animal hospital.

Design—Prospective study.

Sample Population—Bacteria recovered from the soles of rubber boots after experimental microbial contamination and exposure to disinfectant solutions or water (water-treated control boots) or no treatment (untreated control boots).

Procedures—Investigators contaminated boots by walking through soiled animal bedding. Swab samples were collected from the sole of 1 untreated boot (right or left); the other boot was treated as investigators stepped through a disinfectant-filled footbath, a disinfectant-filled footmat, or water-filled footmat. Samples were collected 10 minutes after each treatment. Differences in numbers of bacteria recovered from treated and untreated boots were analyzed.

Results—Mean bacterial counts from peroxygentreated boots were 1.3 to 1.4 log10 lower (95.4% to 99.8%) than the counts from untreated boots. Results were similar for footmat- and footbath-treated boots. In contrast, there were no statistically detectable differences in mean bacterial counts in samples collected from water-treated or untreated boots.

Conclusions and Clinical Relevance—Results suggest that footmats and footbaths containing peroxygenbased disinfectant are effective in reducing bacterial contamination on the soles of boots when used in conditions representative of large animal hospitals. Similar results were achieved with use of either footmats or footbaths. The use of footbaths and footmats containing effective disinfectants may help decrease the risk for spread of nosocomial infection but should not be expected to sterilize footwear.

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in Journal of the American Veterinary Medical Association
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effectiveness of various sampling techniques for determining antimicrobial resistance patterns in Escherichia coli isolated from feces of feedlot cattle.

Sample Population—Fecal samples obtained from 328 beef steers and 6 feedlot pens in which the cattle resided.

Procedure—Single fecal samples were collected from the rectum of each steer and from floors of pens in which the cattle resided. Fecal material from each single sample was combined into pools containing 5 and 10 samples. Five isolates of Escherichia coli from each single sample and each pooled sample were tested for susceptibility to 17 antimicrobials.

Results—Patterns of antimicrobial resistance for fecal samples obtained from the rectum of cattle did not differ from fecal samples obtained from pen floors. Resistance patterns from pooled samples differed from patterns observed for single fecal samples. Little pen-to-pen variation in resistance prevalence was observed. Clustering of resistance phenotypes within samples was detected.

Conclusions and Clinical Relevance—Studies of antimicrobial resistance in feedlot cattle can rely on fecal samples obtained from pen floors, thus avoiding the cost and effort of obtaining fecal samples from the rectum of cattle. Pooled fecal samples yielded resistance patterns that were consistent with those of single fecal samples when the prevalence of resistance to an antimicrobial was > 2%. Pooling may be a practical alternative when investigating patterns of resistance that are not rare. Apparent clustering of resistance phenotypes within samples argues for examining fewer isolates per fecal sample and more fecal samples per pen. (Am J Vet Res 2002;63:1662–1670)

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in American Journal of Veterinary Research