Fig 4.

UPGMA tree of the O-antigen gene clusters from 26 O103 Escherichia coli strains. Bootstrap values are presented on the corresponding branches, and clusters are in parentheses. EPEC strains are highlighted in yellow, strains with the nleB gene are highlighted in blue, and strains highlighted in red have the T STEC allele for polymorphism wbtD 937 C→T. The unit of measure for the scale bar is the number of nucleotide substitutions per site. IDPH, Idaho Department of Public Health; SDSU, South Dakota State University.