Figure 3.

Genetic relationships of cattle and human isolates of E. coli strains from across the United States. The dendrogram was produced by NJ analysis of binary files representing the presence and absence of 1,250 OBGS products from each strain derived from six different OBGS-primer combinations (tree length = 1398, consistency index = 0.61, retention index = 0.81 with 235 characters). Among the O157:H7 strains, 892 of 1,250 bands were conserved. The tree is rooted using the K-12 derivative MC1061 as an outgroup. The state from which each strain originated is indicated by the two-letter abbreviation in parentheses. Human isolates have an H at the end of the designation and bovine isolates are in bold. The year of isolation is indicated to the right. Bootstrap percentages, derived from 1,000 replications of a NJ search, are indicated at nodes scoring >50%.