Clostridioides difficile Colitis

What is C. difficile Colitis?

Clostridioides difficile (C. diff) is a bacterium that can cause a severe infection in the colon, known as C. diff colitis or pseudomembranous colitis. This bacterium is commonly present in the environment and in the gut of some healthy individuals. An infection typically occurs when the normal balance of healthy gut bacteria is disrupted, most often by taking antibiotics. This allows C. diff to multiply rapidly and produce toxins that damage the lining of the colon, leading to inflammation and severe diarrhea. C. diff is a major cause of hospital-acquired infections, but it is also increasingly seen in the community.

What are the symptoms?

The primary symptom of a C. diff infection is watery diarrhea, which occurs at least three times a day for two or more days. The severity can range from mild to life-threatening.

• Mild to Moderate Infection: Watery diarrhea, mild abdominal cramping and tenderness.
• Severe Infection: Watery diarrhea up to 10 to 15 times a day, intense abdominal cramping and pain, fever, nausea, loss of appetite, and dehydration. You may also see pus or blood in the stool.
• Fulminant Colitis: This is a rare, life-threatening form of C. diff infection that can lead to a dangerously enlarged colon (toxic megacolon) or a hole in the colon (perforation). Symptoms include severe pain, a distended abdomen, high fever, and signs of shock.

What causes a C. diff infection?

C. diff infection is caused by the C. difficile bacterium. The bacteria produce two main toxins, Toxin A and Toxin B, which cause inflammation and damage to the colonic mucosa. The infection almost always develops after the normal gut flora has been altered, allowing C. diff to overgrow.

• Antibiotic Use: This is the most significant risk factor. While nearly any antibiotic can be a trigger, broad-spectrum antibiotics like clindamycin, fluoroquinolones, and cephalosporins are most commonly implicated.
• Healthcare Exposure: C. diff spores are very resilient and can survive on surfaces for long periods. They are easily spread in hospitals and long-term care facilities, where many people are on antibiotics and are more vulnerable.
• Advanced Age: Being 65 or older significantly increases the risk.
• Weakened Immune System: Conditions like inflammatory bowel disease, cancer, or immunosuppressive medications increase susceptibility.
• Proton Pump Inhibitors (PPIs): Use of these acid-reducing medications has been associated with an increased risk of C. diff infection.

How is C. diff diagnosed?

The diagnosis of C. diff is made by testing a stool sample for the presence of the C. difficile bacteria's toxins or the genes that produce the toxins.

• Stool Testing: A diarrheal stool sample is collected and sent to the laboratory. The most common modern tests are nucleic acid amplification tests (NAATs), such as PCR, which are very sensitive and detect the C. diff toxin genes.
• Colonoscopy/Sigmoidoscopy: Endoscopy is not usually needed for diagnosis. However, in severe cases or when the diagnosis is unclear, it may be performed. The characteristic finding is 'pseudomembranes'—yellowish-white plaques on the surface of an inflamed colon.

How is C. diff colitis treated?

Treatment depends on the severity of the infection. The first step, if possible, is to stop the antibiotic that triggered the infection.

• Antibiotics: Specific antibiotics are used to kill the C. diff bacteria.
  • Fidaxomicin: An oral antibiotic that is often recommended as a first-line treatment due to its effectiveness and lower rate of recurrence.
  • Vancomycin: An oral antibiotic that is also a first-line treatment for an initial episode of C. diff.
  • Metronidazole: This was once a common first-line treatment but is now reserved for mild cases when other options are not available, due to lower efficacy.
• Fecal Microbiota Transplantation (FMT): For patients who have recurrent C. diff infections, FMT is a highly effective treatment. It involves transferring stool from a healthy donor into the patient's colon to restore a healthy balance of gut bacteria.
• Surgery: In rare cases of fulminant colitis with toxic megacolon, perforation, or shock that does not respond to medical therapy, emergency surgery to remove the colon (colectomy) may be life-saving.

Can C. diff come back after treatment?
Yes, recurrence is a significant problem with C. diff infections, occurring in about 20-35% of people after an initial episode. The risk of further recurrence increases with each subsequent episode. Treatments for recurrent C. diff include a tapered or pulsed course of vancomycin, fidaxomicin, or fecal microbiota transplantation (FMT).

Is C. diff contagious?
Yes, C. diff is contagious. The bacteria form spores that can live outside the body for a long time and are spread through contact with contaminated surfaces or hands. This is why strict handwashing and infection control measures are so important, especially in hospitals.

• Paquette IM, Stewart DB. Clostridium difficile Infection. In: Steele SR, Hull TL, Hyman N, Maykel JA, Read TE, Whitlow CB, eds. The ASCRS Textbook of Colon and Rectal Surgery. 4th ed. Springer; 2022:879-891.
• Centers for Disease Control and Prevention. C. diff (Clostridioides difficile). Accessed September 28, 2026. https://www.cdc.gov/c-diff/index.html
• McDonald LC, Gerding DN, Johnson S, et al. Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA). Clin Infect Dis. 2018;66(7):e1-e48.