Characterization of serotypes and outer membrane protein profiles in enteroaggregative Escherichia coli strains

Twenty-four Escherichia coli strains mainly isolated from children with dia rrhea in Sao Paulo, and showing characteristics of enteroaggregative E, col i (EAEC), were characterized by serotyping and outer membrane protein (OMP) profiles. The relationship between these characteristics was evaluated, as well as the usefulness of OMP profiles in the clonal analysis of EAEC stra ins. All strains presented aggregative adherence to HeLa cells and were cla ssified in two groups based on their interaction with the EAEC DNA probe. A diversity of serotypes and OMP profiles was observed in both groups studie d. Although no significant correlation between serotypes and OMP profiles w as observed, unique OMP profiles were identified in 80% of the probe-positi ve strains which were distributed in only 4 OMP profiles. This result may i ndicate the presence of a few clones in the probe-positive group, On the ot her hand, probe-negative strains seem to constitute a more diverse group. I n general, the observed heterogeneity in serotypes and OMP profiles describ ed in the present study suggest a great genetic diversity in EAEC isolates of either the same or different serotypes and in strains presenting the sam e EAEC markers identified in our community.