Epithelial cell invasiveness of non-enteropathogenic serotypes of Escherichia coli

Current evidence suggests that enteropathogenic Escherichia coli (EPEC) of traditional serotypes possess a three-stage pathogenesis: localised adherence (LA), to, attachment-effacement (AE) of, and penetration of, enterocytes, all of which can be reproduced in tissue culture models in vitro. Three E. coli isolates of non-traditional serotypes (02:H2, 02:H25 and 015:H2) isolated from children with diarrhoea were previously shown to be positive for LA and AE activities in laboratory models. In the present study, they were, in addition, shown to be positive for invasion of a HEp-2 cell monolayer. These findings further establish the pathogenicity of non-traditional serotypes of E. coli and their role in the causation of diarrhoea.