Enteritis, Gastroenteritis, Ileitis, Jejunitis, Sigmoiditis

What is Colitis?

Colitis refers to inflammation of the large intestine (colon). The inflammation may be due to infection by virus, ameba, or a bacterium (such as Campylobacter) that produces toxins that irritate the lining of the intestine. Colitis may also be caused by bacteria that directly infect the colon lining.

In antibiotic-associated colitis, antibiotics taken over a prolonged period of time cause a form of colitis. The bacteria normally living in the intestine are killed by extended use of the antibiotics, allowing another type of bacterium (Clostridium difficile) to proliferate and produce a toxin that irritates the colon. The irritative effect of the antibiotic itself can also cause colon inflammation.

In the elderly, ischemic colitis can occur when narrowing of the blood vessels (atherosclerosis) impairs the blood supply to the intestinal wall. Another serious intestinal disorder, ulcerative colitis, usually starts in young adulthood and is of unknown origin.

How is it diagnosed?

  • History: Symptoms of colitis include watery diarrhea containing mucus, pus, or blood, abdominal pain, tenderness, or spasm (colic), and intermittent or irregular fever.
  • Physical exam: A digital exam (with gloved finger) of the rectum may be done to detect irregularities. Bowel sounds are assessed.
  • Tests A sample of feces is examined for parasites, and a culture or stained smear is microscopically analyzed to identify bacteria. A sigmoidoscopy, using a flexible viewing scope (sigmoidoscope), examines the inside of the rectum and colon for inflammation or ulceration of its lining. Small samples (biopsies) of the inflamed areas may be taken for examination under the microscope. A barium enema (x-ray using barium as the contrast medium) identifies areas of narrowing or severe inflammation.

How is Colitis treated?

Most infections that cause colitis resolve without treatment. However, infections caused by Campylobacter may need to be treated with antibiotics. Amebic infections are sometimes treated with anti-amebic medication (amebicides), and Clostridium infections can be treated with amebicides or antibiotics.

When caused by ischemia, colitis is treated by surgical removal of the diseased section of the colon. Ulcerative colitis is treated with a combination of anti-inflammatory drugs (corticosteroids), a special diet, and vitamin supplements.


Information Brand Generic Label Rating
Metronidazole Flagyl Metronidazole Off-Label Amoxil Amoxicillin Off-Label
Cipro Cipro Ciprofloxacin Off-Label
Principen price Principen Ampicillin On-Label

Sumycin (Tetracycline), Noroxin (Norfloxacin), Ilosone (Erythromycin), Keflex (Cephalexin)

What might complicate it?

Prolonged diarrhea may result in dehydration and electrolyte imbalance. In severe cases of colitis, hemorrhage and perforation of the colon can occur.

Predicted outcome

Most cases of colitis caused by infection resolve without treatment. If treatment is necessary, the infections usually respond well to the medication. Antibiotic-associated colitis usually resolves once the antibiotic therapy has been discontinued. Prognosis for ischemic colitis may depend on the extent of damaged colon that had to be removed. Ulcerative colitis is a chronic condition requiring long-term management.


Conditions with similar symptoms include Crohn's disease, proctitis, diverticular disease, or intestinal cancer.

Appropriate specialists

Gastroenterologist and general practitioner.

Last updated 17 December 2015


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