Correlation between the usage volume of veterinary therapeutic antimicrobials and resistance in Escherichia coli isolated from the feces of food-producing animals in Japan.

We compared the overall usage of veterinary therapeutic antimicrobials in Japan to the proportion of antimicrobial-resistant. Escherichia coli isolated from the feces of apparently healthy food-producing animals in 2001. The annual sales volume of veterinary antimicrobials, which is published and accumulated information, was subdivided according to the target animal species (cattle, pigs, broiler chickens, and layer chickens). The antimicrobial susceptibility of the isolates was examined against 7 classes of 11 antimicrobials. The rates of antimicrobial resistance among the isolates were found to correlate significantly with the usage of antimicrobial agents in cattle, pigs, and broiler and layer chickens. Therefore, the overall usage of veterinary antimicrobials appears to contribute to the appearance of antimicrobial resistance in E. coli isolates from apparently healthy food-producing animals.