Antimicrobial resistance patterns of Campylobacter from feedlot cattle*.
OBJECTIVE
This study examined 448 Campylobacter strains isolated in 1999 and 2000 from US feedlot cattle for resistance to 12 antimicrobials.


RESULTS
Isolates were tested for antimicrobial susceptibility using the E-test method. Approximately 60% (n = 267) were resistant to one or more antimicrobials, and 19.6% (n = 88) were resistant to two or more antimicrobials. Of the Campylobacter jejuni isolates, 49.1% (n = 187) were resistant to tetracycline, 10.2% (n = 39) were resistant to nalidixic acid, 8.4% were resistant to trimethoprim/sulfamethoxazole, and 1.8% (n = 7) were resistant to ciprofloxacin. Resistance to any of the other eight antimicrobials was 1.3% or less, but 14.4% (n = 55) were resistant to two or more antimicrobials. In the Campylobacter coli group, 65.7% (n = 44) were resistant to tetracycline, 52.2% (n = 35) were resistant to trimethoprim/sulfamethoxazole, 22.4% (n = 15) were resistant to nalidixic acid, and 9.0% (n = 6) were resistant to ciprofloxacin. Resistance to any of the remaining eight antimicrobials was 3.0% or less, although 49.3% (n = 33) were resistant to two or more antimicrobials.


CONCLUSIONS
Although antimicrobials are widely used in US feedlot cattle production, our results demonstrate generally low levels of resistance to a broad range of commonly used antimicrobials relative to other recent studies.


CONCLUSIONS
Resistance data on Campylobacter isolated from this major US livestock commodity is lacking. This overview enhances current knowledge and provides a basis for further studies.
Englen
M D
MD
USDA-ARS, Bacterial Epidemiology and Antimicrobial Resistance Research Unit, Richard B. Russell Agricultural Research Center, Athens, GA 30605-2720, USA. menglen@saa.ars.usda.gov
Fedorka-Cray
P J
PJ
Ladely
S R
SR
Dargatz
D A
DA
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002167:Campylobacter / Q000187:drug effects*; D017000:Campylobacter coli / Q000187:drug effects; D016123:Campylobacter jejuni / Q000187:drug effects; D002417:Cattle; D002939:Ciprofloxacin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D008826:Microbial Sensitivity Tests / Q000379:methods; D009268:Nalidixic Acid / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D013752:Tetracycline