Rapid and simple determination of the Escherichia coli phylogenetic group

Phylogenetic analysis has shown that Escherichia coli is composed of four m ain phylogenetic groups (A, B1, B2, and D) and that virulent extra-intestin al strains mainly belong to groups B2 and D. Actually, phylogenetic groups can be determined by multilocus enzyme electrophoresis or ribotyping, both of which are complex, time-consuming techniques. We describe a simple and r apid phylogenetic grouping technique based on tripler PCR. The method, whic h uses a combination of two genes (chuA and yjaA) and an anonymous DNA frag ment, was tested with 230 strains and showed excellent correlation with ref erence methods.