Clonal diversity and virulence factors in strains of Escherichia coli of the classic enteropathogenic serogroup O114.

Eighty-eight Escherichia coli strains of the enteropathogenic (EPEC) group O114 that were isolated from humans and animals in geographically different places and over more than 30 years were examined for virulence markers, O:H serotypes, and for electrophoretic types by multilocus enzyme electrophoresis. Four major genetically tightly related clusters of strains showed close correlation between electrophoretic types and other phenotypic characters. Cluster I contained 35 EPEC class II strains of serotypes O114:H9 and O114:H- and 5 enterotoxigenic E. coli belonging to O114:H21 and O114:H49. Clusters II and III comprised 36 O114:H4, O114:H32, and O114:H- strains; most were of doubtful pathogenicity except one Verotoxin-positive O114:H4 strain isolated from a human with diarrhea. Cluster IV contained 9 classic EPEC strains of serogroup O114:H2 that were characterized by localized adherence to HEp-2 cells and by the EPEC adherence factor.