Abstract
Seventy Escherichia coli isolates recovered from diseased chickens diagnosed with colibacillosis in Henan Province, China, between 2004 and 2005 were characterized for antimicrobial susceptibility profiles via a broth doubling dilution method. Overall, the isolates displayed resistance to trimethoprim-sulfamethoxazole (100%), oxytetracycline (100%), ampicillin (83%), enrofloxacin (83%), and ciprofloxacin (81%), respectively. Among the phenicols, resistance was approximately 79% and 29% for chloramphenicol and florfenicol, respectively. Molecular detection revealed that the incidence rates of the floR, cmlA, cat1, cat2 and cat3 were 29, 31, 16, 13, and 0%, respectively. Additionally, 10% of the isolates were positive for both floR and cmlA. As these antimicrobial agents may potentially induce cross-resistance between animal and human bacterial pathogens, their prudent use in veterinary medicine is highly recommended.