Figure 2.

Genetic relationships of human and cattle isolates of E. coli O157:H7 from a three-county region in Wisconsin. The dendrogram was produced by NJ analysis of binary files representing presence and absence of 1,251 OBGS segments from each strain with six different OBGS-primer combinations (tree length = 960, consistency index = 0.74, retention index = 0.83 with 168 characters). The tree is rooted with the K-12 derivative MC1061 as an outgroup. Among the O157:H7 strains, 1,060 of 1,251 characters were conserved. Human isolates (H) and cattle (C) isolates were previously described (18, 25). Bootstrap percentages, derived from 1,000 replicates of a NJ search, are indicated at nodes of clusters scoring >50%.