2021 Volume 74 Issue 10 Pages 623-630
Fifty out of 95 suckling piglets, which were from six parous sows, died with diarrhea within 3 weeks on a swine farm in Aichi Prefecture. We examined four dead piglets. Severe purulent serositis was observed in multiple organs, and Escherichia coli O7 antigens were detected in the lesions by immunohistochemical staining. We isolated E. coli O7 strains from almost all organs. The results indicated that the mortality of the suckling piglets was caused by infection of extraintestinal pathogenic E. coli O7. All O7 strains were multi-drug resistant and testing produced CMY‐2‐type AmpC β‐lactamase. The disease outbreak was successfully stopped by administration of ERFX, one of the effective antimicrobials for O7 strains. It appeared that the selective pressure caused by the drugs used frequently on the farm may have contributed to the initiation or severity of the disease.
