Characterization of Pathogenic Escherichia coli Isolates from Food-borne Outbreaks in Gyeonggi-do, Korea

Pathogenic Escherichia coli is an important pathogen causing food-borne diseases in humans and animals. This study investigated the trends of food-borne outbreaks caused by pathogenic E. coli in Gyeonggi-do, Korea, from 2020 to 2022, and analyzed the phenotypic and genotypic characteristics of pathogenic E. coli isolates, including virulence genes, O-serotypes, antimicrobial resistance, and resistance genes. A total of 144 pathogenic E. coli isolates, consisting of 44 (30.6%) enterohemorrhagic E. coli (EHEC), 39 (27.1%) enteroaggregative E. coli (EAEC), 38 (26.4%) enteropathogenic E. coli (EPEC), and 23 (16.0%) enterotoxigenic E. coli (ETEC), were obtained from clinical specimens during the study period. Pathogenic E. coli was prevalently isolated from June to September and in patients aged with 10 to 19 years. The most prevalent virulence genes were vt2 in EHEC, eaeA-bfpA in EPEC, sth-lt in ETEC, and aggR in EAEC. The major O-serotypes were O157, O69, O98, and O6. The resistance to ampicillin (32.6%) and nalidixic acid (32.6%) were highest. Pathogenic E. coli carried blaCTX-M (51.4%), sul1 (27.8%), qnrB (23.6%), and tetA (13.9%). Antimicrobial resistance phenotype was significantly associated with the presence of resistance genes in pathogenic E. coli isolates.