Trimethoprim/sulfamethoxazole-associated pseudomembranous colitis.

A case of TMP/SMX-associated pseudomembranous colitis is described in a patient being treated for a urinary tract infection. Pseudomembranes are visualized on proctosigmoidoscopy, and stool cultures identified Clostridium difficile as the causative organism. The patient was treated successfully with oral vancomycin. A review of this infrequently reported adverse reaction to TMP/SMX is presented, emphasizing etiology and treatment.