Prevalence and antimicrobial resistance of thermophilic Campylobacter spp. from cattle farms in Washington State

The prevalence of thermophilic Campylobacter spp. was investigated in cattle on Washington State farms. A total of 350 thermophilic Campylobacter isolates were isolated from 686 cattle sampled on 15 farms (eight dairies, two calf rearer farms, two feedlots, and three beef cow-calf ranches). Isolate species were identified with a combination of phenotypic tests, hipO colony blot hybridization, and multiplex lpxA PCR. Breakpoint resistance to four antimicrobials (ciprofloxacin, nalidixic acid, erythromycin, and doxycycline) was determined by agar dilution. Campylobacter jejuni was the most frequent species isolated (34.1%), followed by Campylobacter coli (7.7%) and other thermophilic campylobacters (1.5%). The most frequently detected resistance was to doxycycline (42.3% of 350 isolates). Isolates from calf rearer facilities were more frequently doxycycline resistant than isolates from other farm types. C. jejuni was most frequently susceptible to all four of the antimicrobial drugs studied (58.8% of 272 isolates). C. coli isolates were more frequently resistant than C. jejuni, including resistance to quinolone antimicrobials (89.3% of isolates obtained from calves on calf rearer farms) and to erythromycin (72.2% of isolates obtained from feedlot cattle). Multiple drug resistance was more frequent in C. coli (51.5%) than in C. jejuni (5.1%). The results of this study demonstrate that C. jejuni is widely distributed among Washington cattle farms, while C. coli is more narrowly distributed but significantly more resistant.