AB-Induced Diarrhea and Pseudomembranous Colitis

3-10% of adults and 3-15% of children develop diarrhea when given oral antibiotics, the majority DO NOT have colitis. 1-3 out of 100,000 treated outpatients develops pseudomembranous colitis (PC). The oral route is 4x more likely to cause PC than parenteral route (clindamycin). Well absorbed antibiotics that do not reach the colon are less likely to disrupt the colon microflora and cause PC. If untreated, PC can progress to marked dehydration, hypoalbuminemia, and shock associated with risk of septicemia. The causative4 organism is Clostridium dificile.


Treating AB-induced pseudomembranous enterocolitis with antidiarrheals is CONTRAINDICATED! The drug of choice is Flagyl (metronidazole, 750-2000 mg/d, 3-4 divided doses, 7-10 days), which is very effective against C. dificile. Alternative treatments include Vancomycin (Vancocin, 125 mg tid or qid, 7-10 days).


Some people advocate Clindamycin as a 1st line defense. This idea is controversial, and is not regularly recommended.

Category: Pharmacology Notes