Since, Tcds profoundly alter the homeostasis of the ADO system, as described in detail below (Fig. 4) [123, 215–218, 245–247], acting at the level of its generation, modulating the expression and regulation of ARs and finally interacting with the ARs, can affect several biological effects which all together could influence the course of CDI. This evidence concerns the gene ADO and clostridium difficile infection.