Prevalence of O-serogroups, virulence genes and F18 antigenic variants in Escherichia coli isolated from weaned piglets with diarrhea in Korea during 2008-2016.

To diagnose the colibacillosis, the detection of O-serogroups and virulence genes has been recommended worldwide. The prevalence of the viruence factors can fluctuate over time. The objectives of this the present study were to determine the prevalence of O-serogroups, virulence genes, and F18 subtypes among pathogenic Escherichia (E.) coli isolated from weaned piglets with diarrhea in Korea. Between 2008 and 2016, 362 E. coli were isolated from weaned piglets with diarrhea. Hemolysis was determined in blood agar, and O-serogroups were identified using the slide agglutination technique. The genes for the toxins and fimbria were amplified by PCR. Real-time PCR was conducted to discriminate between F18 subtypes. Although the most prevalent serogroup was O149 (11.3%) for last 9 years, O139 (19.1%) became the most prevalent in recent years (2015-2016). The most predominant pathotype was enterotoxigenic E. coli (61.4%). The frequencies of shiga-like toxin-producing E. coli (23.4%), O139 (19.1%), Stx2e (35.1%), and F18ab (48.7%) increased over the most recent years. Although enterotoxigenic E. coli was the most predominant pathotype, the frequencies of O139, Stx2e, STEC, and F18ab increased over the most recent years. These results demonstrate that there were temporal changes of predominant O-serogroups and virulence genes over the last decade in Korea. These findings can be a feasible data for epidemiology and control measures for enteric colibacillosis in Korean piggeries.