Genetic relationships and virulence factors among classical enteropathogenic Escherichia coli serogroup O126 strains.

Thirty-nine Escherichia coli strains of the enteropathogenic (EPEC) serogroup O126 isolated from sporadic and outbreak cases of infantile diarrhoea between 1982 and 1988 were studied. These strains consisted of four serotypes showing close genetic relationships between their virulence markers, outer-membrane protein and lipopolysaccharide profiles, and electrophoretic types by multilocus enzyme electrophoresis. None of these strains exhibited localised adherence to HEp-2 cells or the attaching-effacing properties of classical type I EPEC. Of the 39 strains, 31 were of serotype O126:H12 and enterotoxigenic; one strain was serotype O126:H10 and enteroaggregative. The remaining six strains of serotype O126:H21 and one strain of serotype O126:H8 harboured no known virulence factors for diarrhoeagenic E. coli.