Disclosed are pharmaceutical compositions comprising the compound 2,2'-di(pyridin-4-yl)-1H,1'H-5,5'-bibenzo[d]imidazole, or a pharmaceutically acceptable N-oxide, salt, hydrate or solvate thereof, and a pharmaceutically acceptable excipient. The compositions find application in methods of treating infection with Clostridium difficile and in methods of treating Clostridium difficile-associated disease (CDAD).