Fig. 1

Maximum likelihood phylogeny of 44 strains of C. sordellii of clinical and veterinary origin from the UK, USA and Australia. Scale bar denotes nucleotide changes per position. 1000 bootstrap replicates were run resulting in bootstrap support values of greater than 89 % for all nodes. Phylogenetic relationship between C. difficile MLST genes and their C. sordellii homologues was used to establish the root. *, outlying strains not in a clade; pL, strains carrying tcsL on pCS1-1 or pCS1-2; pLH, strain carrying tcsL and tcsH on pCS1-3; p, strains carrying pCS1-4 or similar plasmid lacking the PaLoc. Encircled numbers indicate hypothesised points of entry of pCS1 type plasmids (see discussion)