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  • Author or Editor: F. William Pierson x
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Objective—To measure minimum inhibitory concentrations (MIC) of 17 antimicrobials for Escherichia coli isolates from a turkey operation and assess whether small samples provide precise estimates of geometric mean MIC.

Design—Prospective study.

Sample Population—105 clinical isolates from birds and 1,104 fecal isolates from 20 flocks (poults and finisher hens).

Procedure—A Mueller-Hinton broth dilution panel was used to measure MIC, and MIC of fecal and clinical isolates were compared. We drew random samples of 5, 10, 15, 20, 25, 30, 35, 40, and 45 isolates from each finisher flock and between 100 and 105 isolates from 5, 7, 10, and 20 flocks. Antimicrobial usage was determined for enrolled flocks.

Results—Six of 12 poult and 18 of 20 finisher flocks had been treated with antimicrobials, often for respiratory illnesses consistent with colibacillosis. All birds received gentamicin at the hatchery. More fecal than clinical isolates were resistant to ampicillin; however, more clinical isolates were resistant to ciprofloxacin, gentamicin, and sulfamethoxazole. Precise estimates of geometric mean MIC for flocks were obtained when ≥ 15 fecal isolates were obtained per flock and, for the operation, when 105 isolates were obtained from ≥ 7 flocks.

Conclusions and Clinical Relevance—Antimicrobial usage was common and may have contributed to the resistance patterns of isolates. With a modest allocation of laboratory resources, producers can monitor antimicrobial susceptibilities of clinical and fecal E coli to manage risks of antimicrobial usage and resistance. (J Am Vet Med Assoc 2002;221:411–416)

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in Journal of the American Veterinary Medical Association


Objective—To identify risk factors associated with the spread of low pathogenicity H7N2 avian influenza (AI) virus among commercial poultry farms in western Virginia during an outbreak in 2002.

Design—Case-control study.

Procedure—Questionnaires were used to collect information about farm characteristics, biosecurity measures, and husbandry practices on 151 infected premises (128 turkey and 23 chicken farms) and 199 noninfected premises (167 turkey and 32 chicken farms).

Results—The most significant risk factor for AI infection was disposal of dead birds by rendering (odds ratio [OR], 7.3). In addition, age ≥ 10 weeks (OR for birds aged 10 to 19 weeks, 4.9; OR for birds aged ≥ 20 weeks, 4.3) was a significant risk factor regardless of poultry species involved. Other significant risk factors included use of nonfamily caretakers and the presence of mammalian wildlife on the farm. Factors that were not significantly associated with infection included use of various routine biosecurity measures, food and litter sources, types of domestic animals on the premises, and presence of wild birds on the premises.

Conclusions and Clinical Relevance—Results suggest that an important factor contributing to rapid early spread of AI virus infection among commercial poultry farms during this outbreak was disposal of dead birds via rendering off-farm. Because of the highly infectious nature of AI virus and the devastating economic impact of outbreaks, poultry farmers should consider carcass disposal techniques that do not require offfarm movement, such as burial, composting, or incineration. (J Am Vet Med Assoc 2005;226:767–772)

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in Journal of the American Veterinary Medical Association