Antimicrobial agent-associated colitis and diarrhea.

Diarrhea is a common, often self-limited complication of therapy with a wide variety of antimicrobial agents. Antimicrobial agent-associated pseudomembranous colitis is almost always caused by C. difficile; approximately one-third of cases of nonspecific colitis or diarrhea without colitis are also caused by C. difficile. The organism can be detected by culture of fecal material and by demonstration of a neutralizable cytotoxin in feces. Although orally administered vancomycin is extremely effective for treatment of C. difficile-induced diarrhea or colitis, therapy should be reserved for the more seriously ill patient or the patient with protracted diarrhea because of the potential for multiple relapses following discontinuation of vancomycin.