Vancomycin/Flagyl. Antibiotics (especially clindamycin) select for the overproliferation of clostridium difficile in the colon which can lead to profuse, watery diarrhea (and ultimately megacolon). For severe cases, a course of IV Metronidazole (flagyl) or oral vancomycin is the mainstay therapy. Fidaxomicin (dificid) is a newer drug that is also being used to selectively target pathogenic c. Difficile.
Metronidazole. Metronidazole is a standard of care for c.Diff diarrhea.