CHA RA CTERIZATION OF VEROTOXIN-PRODUCING STRA INS OF ENTEROPATHOGENIC ESCHERICHIA COLI (EPEC) FROM CHILDREN WITH DIA RRHOEA: EFFECTS OF THE TOXIN ON RABB IT INTESTINE

249 enteropathogenic Escherichia coli (EPEC) strains from faecal samples of 90 children with diarrhoea were examined for verotoxin (VT) production. Polymyxin B extracts of 61 strains belonging to 9 serogroups from 35 children produced various verotoxins (VTs). The titre of these various VTs ranged from I :40 to I: 12HO. Of the 26 (43.6%) adherent strains, 19 (73%) exhibited localized adherence (LA) and 7 (27%) manifested enteroadherent-aggregative (EA-Agg) patterns. The remaining 35 strains were nonadherent. Verotoxin producing EPECs elicited diverse effects on rabbit intestine ranging from no effect to severe damage to epithelial architecture, irrespective of their adherence patterns of HEp-2 cells. In conclusion, as far as EPEC pathogenesis is concerned, the role of verotoxins could not be established, but strains producing moderate to high levels of verotoxins may have an increased pathogenicity over non-producers.