Characterization of genes associated with internalization of enteroaggregative Escherichia coli

On animal models enteroaggregative Escherichia coli (EAEC) can cause mild, but significant mucosal damage, suggesting the invasive capability of these strains. In the study we investigated the ability of typical, aggR-positive and atypical, aggR-negative EAEC isolates to enter intestinal epithelial Int407 cells in relation to the distribution of genes encoding the putative invasins described among pathogenic E. coli categories. The results demonstrated that regardless of origin and affiliation to typical and atypical EAEC, most isolates examined were internalized by the epithelial cells to different extent. Although as many as 50 (84.3%) EAEC demonstrated a variety of combinations of the aggB, afaD, ipaH and tia genes determined, there was no correlation between the invasion efficiency of these strains and the presence of any particular gene involved in invasion. Most of EAEC examined belonged to phylogenetic group B2 and D.