Clostridium difficile is a gram-positive, spore-forming, toxin-producing anaerobic bacillus that is being increasingly implicated as the leading cause of diarrhea and colitis, particularly in hospitalized, elderly patients. Studies to date suggest that C. difficile toxins A and B play a major role in the observed colonic inflammation and associated disease pathogenesis; however, the role of other potential bacterial factors at present remains unknown. Early effects of C. difficile on host intestinal epithelia include modest induction of innate immune responses with progressive loss of intestinal epithelial cell barrier function and cell death.