A national surveillance of antimicrobial resistance in Escherichia coli isolated from food-producing animals in Japan.

A nationwide investigation of antimicrobial susceptibility in Escherichia coli isolated from food-producing animals was performed in Japan. MICs of 18 antimicrobial agents were determined for a total of 1018 isolates. Higher resistance rates were observed against sulfadimethoxine, oxytetracycline and dihydrostreptomycin, followed by ampicillin and kanamycin. Resistance was more frequently observed among broiler isolates, followed by isolates from pigs. Almost 10% of broiler isolates were resistant to fluoroquinolones and extremely high MICs (100 mg/L) were observed. In general, antimicrobial resistance rates in E. coli have declined in recent years, with the exception of resistance to fluoroquinolones among broiler isolates, which has increased.