Diversity of surface structures and virulence genetic markers among enteroaggregative Escherichia coli (EAEC) strains with and without the EAEC DNA probe sequence

The expression of surface structures and the presence of DNA sequences related to putative virulence factors were investigated in 22 enteroaggregative Escherichia coli strains (EAEC). Fimbria was the most frequent (72.7%) structure identified. Only strains hybridising with the EAEC DNA probe carried aggA, but one strain produced a similar but unrelated bundle-like structure. All probe-positive and 62.5% of the probe-negative strains carried the virulence genes tested; aspU and irp2 prevailed among the former strains. The EAEC probe-positive strains were more diverse, and some of these strains, which promoted cell detachment, also carried the hly and pap sequences, thus suggesting they might represent uropathogenic E. coli.