Almost any antibiotic can cause pseudomembranous colitis. The bacterium Clostridium difficile, which is normally present in the intestine, may overgrow when antibiotics are taken. The bacteria release a powerful toxin that causes the symptoms. The lining of the colon becomes raw and bleeds. In addition to antibiotic use, chemotherapy, advanced age, recent surgery, and history of previous pseudomembranous colitis are risk factors for this condition. Ampicillin, clindamycin, and cephalosporins are the most common antibiotics associated with this disease in children. Pseudomembranous colitis is rare in infants less than 12 months old because they have protective antibodies from the mother and because the toxin does not cause disease in most infants.
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