Clostridium Difficile Colitis (Antibiotic-Associated Colitis, C. difficile Colitis, C. diff, C diff,)

  • Medical Author:
    Dennis Lee, MD

    Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

  • Medical Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Quick GuideBacterial Infections 101: Types, Symptoms, and Treatments

Bacterial Infections 101: Types, Symptoms, and Treatments

How is Clostridium difficile colitis diagnosed?

History

A history of antibiotic use is important in the diagnosis of C. difficile colitis. Patients taking antibiotics (or recently having taken antibiotics) who develop abdominal pain, cramps and diarrhea are usually tested for C. difficile infection. However, doctors do not always wait for the appearance of diarrhea to start testing for C. difficile since in rare instances C. difficile can cause abdominal pain and tenderness without diarrhea.

Laboratory tests

Patients with C. difficile colitis often have elevated white blood cell counts in the blood, and, in severe colitis, the white blood cell counts can be very high (20,000 to 40,000). Patients with C. difficile colitis also often have white blood cells in their stool when a sample of stool is examined under a microscope. Elevated white blood cell counts and white blood cells in the stool, however, only demonstrate that there is colitis and not that the cause of the colitis is C. difficile. More specific tests are necessary to determine whether C. difficile is the cause of the colitis.

The most widely used test for diagnosing C. difficile colitis is a test that detects toxins produced by C. difficile in a sample of stool. There are two different toxins, toxin A and toxin B, both capable of causing colitis. Accurate tests for both toxins are available commercially for use in all laboratories. Unfortunately, like most tests in medicine, these tests for toxins are not perfect; both false positive tests (finding toxins when there is no C. difficile) and false negative tests (not finding toxins when C. difficile is present) can occur. Therefore, other tests such as flexible sigmoidoscopy and colonoscopy often are necessary to look for pseudomembranes that are characteristic of C. difficile colitis.

Flexible sigmoidoscopy and colonoscopy

Flexible sigmoidoscopy is an examination in which a doctor inserts a flexible fiberoptic tube with a light and a camera on its end into the rectum and sigmoid colon. (The sigmoid colon is the segment of the colon that is closest to the rectum.) In most patients with C. difficile colitis, the doctor will find pseudomembranes in the rectum and the sigmoid colon. However, some patients with C. difficile colitis will have pseudomembranes only in the right colon (the segment of the colon farthest from the rectum). Patients with pseudomembranes confined to the right colon require colonoscopy in order to see the pseudomembranes. (A colonoscope is a longer version of the flexible sigmoidoscope that is long enough to reach the right colon.)

X-rays

X-ray examinations and computerized tomography (CT) examinations of the abdomen will occasionally demonstrate thickening of the wall of the colon due to inflammation, but these X-ray findings also are non-specific and only demonstrate that colitis is present. They do not demonstrate the cause of the colitis, for example, C. difficile.

How is Clostridium difficile colitis treated?

Treatment of C. difficile colitis includes:

  • correction of dehydration and electrolyte (mineral) deficiencies,
  • discontinuing the antibiotic that caused the colitis, and
  • using antibiotics to eradicate the C. difficile bacterium.

In patients with mild colitis, stopping the antibiotic that caused the infection may be enough to cause the colitis and diarrhea to subside. In most cases, however, antibiotics are needed to eradicate the C. difficile bacteria.

Antibiotics that are effective against C. difficile include metronidazole (Flagyl), and vancomycin (Vancocin). These two antibiotics usually are taken orally for 10 days. Both antibiotics are equally effective. With either antibiotic, fever usually will resolve in one or two days, and diarrhea in three or four days. Several other antibiotics, some new and some older, have been used effectively against C. difficile recently, most notably fidaxomicin (Dificid).

The choice of which antibiotic to use depends on the individual patient's situation and the preferences of the treating doctor. Some doctors will prescribe metronidazole first because it is much less expensive than vancomycin. Vancomycin may be reserved for patients who do not respond to metronidazole, are allergic to metronidazole, or develop side effects from metronidazole. Other doctors will prescribe vancomycin first for severe colitis because vancomycin can achieve much higher antibiotic levels in the colon than metronidazole (and higher antibiotic levels theoretically would be more effective in killing bacteria).

Why are there relapses of Clostridium difficile colitis?

Approximately 10% to 20% of successfully treated patients can experience a relapse of C. difficile colitis with recurrence of diarrhea, abdominal cramps, and abdominal pain. Relapses typically occur days or even weeks after treatment is stopped. Some patients may experience several relapses.

The most likely explanation for relapse is that the C.difficile has not been completely eradicated by the initial course of antibiotics. C. difficile in its active bacterial form is killed by either metronidazole or vancomycin, but the spores are resistant to killing. Several days after stopping antibiotics, the surviving spores transform into active bacterial forms which will multiply and produce toxins again.

Another reason for relapse is the body's inadequate production of antibodies against the bacterial toxins. Antibodies are proteins that the body produces to fight bacterial, viral, and parasitic infections, as well as to protect the body from the harmful effects of toxins. Therefore, adults who are capable of producing adequate antibodies against C. difficile toxins usually do not develop C. difficile colitis. Some adults who cannot produce these antibodies are susceptible to relapses.

Medically Reviewed by a Doctor on 10/11/2016

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