Pseudomembranous colitis is a specific infection of the large intestine (colon) due to overgrowth of a bacteria called Clostridium difficile.

The Clostridium difficile bacteria is normally present in the intestine. However, it 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.

Ampicillin, clindamycin, and cephalosporins are the most common antibiotics associated with this disease in children. Pseudomembranous colitis is rare in infants younger than 12 months old because they have protective antibodies from the mother and because the toxin does not cause disease in most infants.

Most cases of pseudomembranous colitis happen while the person is in the hospital, because the bacteria can spread from one patient to another.

Risk factors include:

• Advanced age
• Antibiotic use
• Chemotherapy
• Medications that suppress the immune system
• Recent surgery
• Personal history of pseudomembranous colitis

• Abdominal cramps
• Bloody stools
• Low-grade fever
• Urge to have a bowel movement
• Watery diarrhea

Either or both of the following tests will confirm the disorder:

• Colonoscopy or flexible sigmoidoscopy
• Immunoassay for C. difficile toxin

The antibiotic or other medicine causing the condition should be stopped. Metronidazole is usually used to treat the disorder, but vancomycin or rifaximin may also be used.

Electrolyte solutions or fluids given through a vein may be needed to treat dehydration due to diarrhea. In rare cases, surgery is needed to treat infections that get worse or do not respond to antibiotics.

If there are no complications, the outlook is generally good. However, up to 20% of infections may return, requiring additional treatment.

• Perforation (hole) of the colon
• Dehydration with electrolyte imbalance
• Toxic megacolon

Call your health care provider if the following symptoms occur:

• Persistent diarrhea
• Bloody stools after taking antibiotics
• Severe abdominal pain
• Signs of dehydration (dry skin, dry mouth, glassy appearance of the eyes, sunken fontanelles in infants, rapid pulse, confusion, excessive tiredness)

People who have had pseudomembranous colitis should inform their doctors before taking antibiotics again.

Aslam S. An update on diagnosis, treatment, and prevention of Clostridium difficile-associated disease. Gastroenterol Clin North Am. Jun 2006;35(2):315-335.