Prototypal diarrheagenic strains of Hafnia alvei are actually members of the genus Escherichia

The strains were initially identified as Hafnia alvei with a commercial ide ntification system and were reported to contain the eae gene of enteropatho genic Escherichia coli, Results of conventional biochemical analyses, testi ng of susceptibility to cephalothin, lysis by a Hafnia-specific phage, and amplification of the outer membrane protein gene phoE with species-specific primers support the identification of these strains as members of the genu s Escherichia rather than Hafnia alvei. These strains varied from typical E , coli strains by their inability to produce acid from lactose or D-sorbito l and failure to elaborate the enzyme beta-D-glucuronidase, PCR analysis co nfirmed previous findings that the strains were positive for the eae gene a nd negative for other virulence markers present among recognized categories of diarrheagenic E, coli, Our findings support the hypothesis that these s trains are a new category of diarrheagenic isolates belonging to the genus Escherichia and illustrate the importance of using multiple methodologies w hen identifying new bacterial agents of diarrheal disease.