Phylogeny of Escherichia coli and sequence type complex (STc) 131. The phylogram is illustrative only; branch lengths are not to scale, and tree conformation is approximate. Phylogenetic groups are identified with brackets. Each STc included in the present study is labeled; unlabeled branches represent other (unstudied) STs within the indicated phylogenetic groups. Stippled rectangle, STc131; open rectangle within stippled rectangle, ST131-H30 subclone.