Submitted to: Journal of Applied Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/28/2005
Publication Date: 8/1/2005
Citation: Englen, M.D., Cray, P.J., Ladely, S.R., Dargatz, D.A. 2005. Antimicrobial resistance patterns of Campylobacter from feedlot cattle. Journal of Applied Microbiology. 99(2):285-291. Interpretive Summary: The emergence of bacterial pathogens resistant to antimicrobials used to treat human disease has provoked controversy over the use of such drugs in food animal production. We determined the resistance patterns to twelve antimicrobials among a geographically diverse group of the food-borne pathogen, Campylobacter, isolated from feedlot cattle. Major findings included 55% resistant to one or more antimicrobials, and nearly 14% resistant to two or more agents. Much of the resistance was accounted for by tetracycline, nalidixic acid and ciprofloxacin. Tetracycline, and to a lesser degree ciprofloxacin, is used in feedlot cattle. However, although macrolides such as erythromycin are also widely used, we found very low levels of resistance to these antimicrobials. This work will be useful to beef producers, regulatory agencies and researchers studying antimicrobial resistance, providing valuable new information on resistance in an important pathogen from a major sector of the US food supply.
Technical Abstract: We examined 461 Campylobacter isolates from healthy feedlot cattle for susceptibility to 12 antimicrobials (AMs). This group consisted of 82.7% (n=381) C. jejuni, 14.5% (n=67) C. coli, and 2.8% (n=13) non-coli/jejuni that were designated as Campylobacter spp. The AMs tested included azithromycin (AZ), clindamycin (CM), erythromycin (EM), gentamicin (GM), naladixic acid (NA), ciprofloxacin (CI), chloramphenicol (CL), imipenim (IP), amoxicillin/clavulanic acid (XL), cefepime (PM), tetracycline (TC) and trimethoprim/sulfamethoxazole (TS). Approximately 55% (n=254) of the isolates were resistant to 1 or more AM, and 13.7% (n=63) were resistant to 2 or more AMs. Of the C. jejuni isolates, 49.1% (n=187) were resistant to TC, 10.2% (n=39) were resistant to NA, and 1.8% were resistant to CI (n=7). Resistance to any of the other 9 AM was 1.0% or less; 10.2% (n=39) were resistant to 2 or more AMs. In the C. coli group, 65.7% (n=44) were resistant to TC, 20.9% (n=14) were resistant to NA, and 9.0% were resistant to CI (n=6). Resistance to any of the remaining 9 AMs was 3.0% or less, although 23.9% (n=16) of the C. coli isolates were resistant to 2 or more AMs. Among Campylobacter spp., resistance to TC was 46.2% (n=6), 38.5% (n=5) to NA, 23.1% (n=3) to AZ, 23.1 % (n=3) to CM, and 15.4% (n=2) to CI; 61.5% (n=8) were resistant to 2 or more AMs.