Antibiotic-associated colitis.

Pseudomembranous colitis, a relatively uncommon and sometimes severe diarrheal disease, recently has been linked to the administration of a number of broad-spectrum antibiotics. The cause has now been identified as a spore-forming clostridial species not previously recognized as a human pathogen. Since the organism is sensitive to moset commonly used antibiotics, its spores may be the key to the disease.