Phylogenetic relationships of EHEC and EPEC sequence types. The sequence types (STs) of EHEC 2 belong to a clonal group (CG 14), which is more closely related to EPEC 2 (CG 17), than EHEC 1 STs (CG 11). The phylogenetic tree was constructed using the Neighbor-joining algorithm based on the Kimura 2-parameter distance matrix of nucleotide substitution. Bootstrap confidence values were based on 1000 replicates. Only those higher than 70% are shown.