Frequency of STs (n = 69) within the clinical isolate collection (n = 1290).

STs are ranked in descending order of abundance. The clade that each ST belongs to is indicated, followed by the associated tcdC allele variant(s) classified as WT (wild type), Δ18 (having an 18 nt deletion in the coiled coil domain), and Δ1stop or TAAstop to indicate truncated variants. N/A: not applicable as all isolates of this ST were non-toxigenic. A more detailed version of this table is also provided as Table S1, to show the frequency of the tcdB-RBD and tcdC alleles associated with each ST.1PCR-ribotypes found in association with each ST. An ST can have more than one ribotype, however, the converse is also true and this, together with the numbers of isolates that were PCR-ribotyped is shown in Table S2 and Fig. S1.