Enteropathogenicity markers in Escherichia coli strains isolated from soft white cheese and poultry in Rio de Janeiro, Brazil Original Research Article

Diarrhoeagenic Escherichia coli is the main cause of infantile diarrhoea in Brazil. Unseasoned soft white cheese and poultry are cheap foods widely consumed by adults and children in Brazilian cities. To assess the risk involved in consumption of these foods, virulence markers were investigated in 575 E. coli colonies isolated from 44 soft white cheese and 39 chicken carcass samples. Escherichia coli colonies were tested with enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC) and O157 antisera and tested for adherence to HEp-2 cells, FAS test, enterohemolysin production, Dean assay for STa and DNA hybridization with eae, EAF, stx and LT-I probes. Shiga toxin (Stx) production by probe-positive strains was tested on Vero cells. Escherichia coli strains of EPEC serogroups O127 and O128 were found in 11·3% of cheese samples and O114, O119 and O158 were found in 10·2% of chicken samples examined. None of these produced localized adherence on HEp-2 cells or hybridized with eae and EAF probes. EIEC, enterotoxigenic E. coli (ETEC) and enterohemolysin-producing E. coli was not detected. Two non-O157 E. coli strains (serotypes O?:H28 and R:H?) isolated from chicken carcasses hybridized with stx2 probe and one of them also hybridized with eae probe. However, none of these strains were positive for enterohaemolysin, FAS, adhered to HEp-2 cells or produced cytotoxic effects on Vero cells.