FIG 1.

Phylogenetic tree of the 46 C. difficile strains based on the genome-wide SNPs. The neighbor-joining phylogenetic tree was constructed based on the SNPs from the core gene sets. C. difficile strain 630 is used as the reference strain for SNP calling. The STs and ribotypes are appended after the strain labels. The tree is annotated by the presence of the tcdA and tcdB genes (green), binary genes (red), and disease severity (blue) at the right side of the dendrogram. The white circles represent the absence of the toxin genes or nonsevere CDI.