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.
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.
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
Sample Population—Polyester transparencies inoculated
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
Objective—To identify factors associated with development of vesicular stomatitis (VS).
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.
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
Animals—1,163 horses stabled at a Thoroughbred
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)
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.
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.
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).
157 production animal veterinarians in the United States.
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.
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.
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
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.
Results—Salmonella 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)
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.
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.
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
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)