Relationship among enterotoxigenic phenotypes, serotypes, and sources of strains in enterotoxigenic Escherichia coli

Abstract

The relationship among O groups, O:H serotypes and enterotoxigenic phenotypes was examined in 76 E. coli strains isolated in Brazil from different sources. Of the 17 heat-labile and -stable enterotoxin (LT/ST)-producing strains whose O antigens were identified, 15 belonged to serotypes O6:H16 (7 strains), O63:H- (5 strains) and O139:H28 (3 strains). All 11 ST strains were in group O128ac, which was represented by 4 O:H serotypes. The 23 LT strains with the O antigen identified were distributed among serotypes of 14 O groups. Colonization factor CAF/I was not found in any of the LT strains, but it was found in 6 LT/ST and 3 ST strains. Each E. coli O:H serotype had a particular fermentation pattern. LT/ST and ST strains were isolated from patients with diarrhea, whereas LT strains were isolated from patients with diarrhea, normal children, food and river water.