Fig. 1

Evolutionary relationships of Clostridium difficile clinical strains. The evolutionary history was inferred using the neighbor-joining method. The optimal tree with the sum of branch length = 182.92187500 is shown. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) are shown next to the branches. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the number of differences method and are in the units of the number of base differences per sequence. The analysis involved 23 nucleotide sequences. All positions containing gaps and missing data were eliminated. There were a total of 7050 positions in the final dataset. Evolutionary analyses were conducted in MEGA7