Advertisement

Antimicrobial susceptibilities of Escherichia coli strains from a turkey operation

Sean F. AltekruseFood and Drug Administration, Center for Veterinary Medicine, 7500 Standish Pl, Rockville, MD 20895.
Present address is the Division of Cancer Epidemiology and Genetics, National Cancer Institute, 6120 Executive Blvd, Room 7082 MSC#7234, Rockville, MD 20852.

Search for other papers by Sean F. Altekruse in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVPM
,
François ElvingerDepartment of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine.

Search for other papers by François Elvinger in
Current site
Google Scholar
PubMed
Close
 Dr med vet, PhD, DACVPM
,
Kyung-Yul LeeFood and Drug Administration, Center for Veterinary Medicine, 7500 Standish Pl, Rockville, MD 20895.

Search for other papers by Kyung-Yul Lee in
Current site
Google Scholar
PubMed
Close
 PhD
,
Linda K. TollefsonFood and Drug Administration, Center for Veterinary Medicine, 7500 Standish Pl, Rockville, MD 20895.

Search for other papers by Linda K. Tollefson in
Current site
Google Scholar
PubMed
Close
 DVM, MPH
,
F. William PiersonDepartment of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine.

Search for other papers by F. William Pierson in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACPV
,
Joseph EifertDepartment of Food Science and Technology, College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.

Search for other papers by Joseph Eifert in
Current site
Google Scholar
PubMed
Close
 PhD
, and
Nammalwar SriranganathanDepartments of Biomedical Sciences and Pathobiology Virginia-Maryland Regional College of Veterinary Medicine.

Search for other papers by Nammalwar Sriranganathan in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVM

Abstract

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)

Abstract

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)