(We provided the chimeric strain with the BtE264 bcpI gene to protect the chimeric strain from CDI by the invading strain (BtE264) because the chimeric strain is inherently less efficient at biofilm formation than BtE264 (Figs. 6, 7, 8) and we sought to only test CDI by the established strain against the invading strain). This evidence concerns the gene CSTB and clostridium difficile infection.