Clostridium difficile is a type of bacteria that is known to cause “opportunistic infections”, or infections when the host is able to be infected easily, usually with the host being in a weakened/compromised state; in this case, most of the cases of C. difficile infections are caused by the lack of other, more benign bacteria colonizing the intestines, usually due to antibiotic treatment. This is akin to introducing wolf packs onto a sheep farm, where there are no competitors/predators for the wolves. As a result, the wolves prosper, at great cost to the sheep and the sheep farmer – a fitting metaphor for both the person infected by C. difficile , and the physician treating it, since C. difficile infections are especially antibiotic-resistant, and are prone to recurrent (i.e: multiple and returning) infections.