The Widespread Occurrence of the Enterohemolysin Gene ehlyA Among Environmental Strains of Escherichia coli

The putative virulence factor enterohemolysin, encoded for by the ehlyA gene, has been closely associated with the pathogenic enterohemorrhagic Escherichia coli (EHEC) group. E. coli isolates from effluents from seven geographically dispersed municipal wastewater treatment plants were screened for the presence of enterohemolysin. A total of 338 E. coli isolates were found to express the ehlyA gene, however none of the isolates contained the toxin encoding genes (stxA or stxB) associated with EHEC. Two of the 338 isolates possessed the virulence factor intimin, encoded for by the eae gene. These findings suggest that the ehlyA gene may be widely distributed among non-EHEC isolates in the environment.