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.