The spread of heat-labile enterotoxin-harboring Escherichia fergusonii in broiler chickens and pigs in Okinawa, Japan.

In 2012, Escherichia fergusonii harboring heat-labile enterotoxin (LT) was isolated from healthy chickens in South Korea. However, little is known about the prevalence, spread, and pathogenicity of the strains for humans and animals. This study aimed to comprehend public health threats such as the distribution, antimicrobial resistance, and genetic diversity of E. fergusonii carrying LTs. E. fergusonii containing LT was isolated from 15.0% (52/346) of chicken fecal samples from all three farms but not from 360 pig samples. The antimicrobial susceptibility testing revealed that over 75% of strains were resistant to ampicillin, kanamycin, nalidixic acid, streptomycin, or tetracycline; additionally, 69.2% (36/52) of strains were resistant to these five antimicrobials. The 52 strains were clustered into eight pulsed-field gel electrophoresis (PFGE) types, with type V and type VI accounting for 84.6%. According to the present study, multiple chicken farms harbored E. fergusonii with similar antimicrobial resistance patterns and genetic clonality. Since the pathogenicity of LT-bearing E. fergusonii to humans and animals, such as food poisoning and sporadic diarrhea via meat, the transmission of the strains, and the dissemination of antimicrobial resistance genes are unknown, additional research is required.