The diagnosis, etiology, epidemiology, and
drug therapy of
antibiotic-associated
pseudomembranous colitis (AAPMC) are reviewed. AAPMC is an uncommon but potentially serious adverse reaction to
therapy with almost any oral or
injectable antibiotic and certain
antineoplastic agents that alter intestinal flora. Proliferation of Clostridium difficile and subsequent release of clostridial
cytotoxins cause pseudomembranous lesions and symptoms such as watery
diarrhea, cramping
abdominal pain, and low-grade
fever. Symptoms can appear from four days after the start of
antibiotic or
antineoplastic therapy to 10 weeks after
therapy has been discontinued.
Drug therapy of AAPMC is directed at reducing the amount of Cl. difficile in the colon and promoting normalization of intestinal flora. Mild cases of AAPMC may respond to discontinuation of the etiologic agent and replacement of fluid and
electrolytes.
Therapy with an anticlostridial
antibiotic is indicated in severe cases; although a seven- to 10-day course of oral
vancomycin hydrochloride is the most widely recognized
therapy, the
drug is expensive and unpalatable. Good results have been reported with oral
metronidazole and with
bacitracin, both of which are less expensive than
vancomycin. For all of these
therapies, relapse rates are 20-39%.
Anion exchange resins may be useful in mild cases of AAPMC. Successful management of AAPMC depends on a complex and ill-defined interrelationship between normal intestinal flora, patient immune response,
antibiotic therapy, and the infecting clostridium strain. For moderate or severe cases of AAPMC,
therapy should begin with
metronidazole or
bacitracin and
vancomycin should be reserved for refractory cases, relapses, or patients with
allergies to the other agents.