O-serogroups, virulence genes of pathogenic Escherichia coli and Pulsed-field gel electrophoresis (PFGE) patterns of O149 isolates from diarrhoeic piglets in Korea

A total of 116 Escherichia (E.) coli isolates isolated from neonatal diarrhoeic piglets were serogrouped and tested for the presence of virulence genes for fimbrial and non-fimbrial adhesins, intimin, and enterotoxins. Pulsed-field gel electrophoresis (PFGE) pulsotypes were also analyzed within O149 enterotoxigenic E. coli (ETEC) isolates. In total, Sixty eight (58.6%) isolates were serotyped. Among them, forty three (63.2%) belonged to 12 serogroups in the descending order: O149, O8, O157, O101, O60, O9, O117, O127, O138, O167, O27 and O97. The predominant pathotype was ETEC (68, 58.6%) which is closely associated with F4 (37, 31.9%) and LT:STb:EAST1 (23, 19.8%) out of the isolates harbouring at least one gene for toxin and/or fimbria. Among non-fimbrial adhesins, porcine attaching and effacing-associated factor (paa) was closely associated with F4-positive isolates (64.7%) rather than F18-positive isolates (5.9%). Adhesion involved in diffuse adherence (AIDA) was only detected in 3 isolates. No eae-positive isolates were detected. The PFGE pattern of 15 O149 isolates was grouped into 12 pulsotypes at 88% similarity level. The results show a wide variety of distinct restriction patterns though all belonged to the same serogroup O149. It is believed that a broad array of O serogroup and virulence genes are associated with neonatal diarrhoea in Korea.