Genotypic Analyses of Escherichia coli Isolated from Chickens with Colibacillosis and Apparently Healthy Chickens in Japan

A genotypic comparison using pulsed-fleld gel electrophoresis (PFGE), amplified ribosomal restriction analysis (ARDRA) as well as PCRs targeting virulence associated genes reported elsewhere in avian pathogenic Escherichia coli (APEC) was made between E. coli strains isolated from chickens with colibacillosis and those from the feces of apparently healthy chickens in Japan. The majority (67%) of clinical isolates belonged to a certain phylogenetic ARDRA but not PFGE cluster, with virulence-related genes carried by ColV plasmid being markedly prevalent. The result suggests that APEC strains originated from the same “ancestor” in the course of E. coli evolution.