Unidentified serogroups of enteropathogenic Escherichia coli (EPEC) associated with diarrhoea in infants in Londrina, Parana, Brazil

Digoxigenin-labelled DNA probes were used to characterise enteropathogenic Escherichia coli (EPEC) isolated in Londrina (Brazil) from faeces samples o f 102 children with diarrhoea, and the results were compared with those obt ained by serogrouping and adherence to HEp-2 cells. The probes employed det ect the gene coding EPEC adherence factor (EAF) and the virulence genes for bundle-forming pilus (bfp) and entero-attaching-effacing (eae) factor. Twe nty-one isolates hybridised with at least one probe, and 11 of them were cl assified as typical EPEC because they hybridised with all three probes, sho wed a pattern of localised adherence (LA) and carried no genes for enteroto xins (ST and LT) or invasion as detected by PCR, Six of the typical EPEC st rains belonged to the classical serotype O119:H6 and one to O111:H6; O anti gens could not be determined in four strains with antisera against O1-O173, All typical EPEC strains carried a 70-MDa plasmid plus two other large pla smids, These data showed that typical EPEC virulence traits may be found in strains not belonging to classical serogroups/serotypes and that molecular identification is required for studying the epidemiology of diarrhoea in c hildren.