Antimicrobial susceptibilities of Escherichia coli strains from a turkey operation.
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.


METHODS
Prospective study.


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


METHODS
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 > or = 15 fecal isolates were obtained per flock and, for the operation, when 105 isolates were obtained from > or = 7 flocks.


CONCLUSIONS
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.
Altekruse
Sean F
SF
Food and Drug Administration, Center for Veterinary Medicine, Rockville, MD 20895, USA.
Elvinger
François
F
Lee
Kyung-Yul
KY
Tollefson
Linda K
LK
Pierson
E William
EW
Eifert
Joseph
J
Sriranganathan
Nammalwar
N
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D015169:Colony Count, Microbial / Q000662:veterinary; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D011201:Poultry Diseases / Q000188:drug therapy* / Q000382:microbiology; D011446:Prospective Studies; D014422:Turkeys
D000900:Anti-Bacterial Agents