Diagram comparing the tcd islands of Pa ATCC43949 with those from two different strains of Pl: TT01 and W14. The tcd island of Pa appears to represent a conserved 'core' of genes found in all strains whilst both Pl strains contain additional copies of tcdA-like, tcdB-like and tccC-like genes inserted adjacent to this core. Note also that the tcd island of Pl W14 has gained several copies of pdl genes that encode lipases thought to be responsible for the release of mature W14 Tc complexes into the bacterial supernatant.
Wilkinson et al. BMC Genomics 2009 10:302 doi:10.1186/1471-2164-10-302