How Long is C Diff Contagious?

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What is C diff?

Clostridium difficile is a gram-positive, anaerobic, spore-forming rod. Clostridial spores are often found in the environment in hospitals and nursing homes. Surfaces and medical equipment can become contaminated if patients and healthcare providers do not use proper handwashing technique. Thus, C. difficile is often a hospital-acquired (or nosocomial) infection. Clostridium difficile infection occurs following antibiotic use, and has been observed following courses of clindamycin, ampicillin, cephalosporins, and fluoroquinolones, although it can occur after use of any antibiotic.

Course of Infection

When the bacterial spores are ingested, they travel to the intestinal tract, germinate into replicating bacteria, and can colonize the large intestine (colon). Only 1% of the general population is colonized with this bacterium, in contrast with 20% of hospital patients (though colonization is not always symptomatic). In patients who have recently taken antibiotics, the normal intestinal flora can be largely diminished, allowing the Clostridium a niche in which to colonize and replicate. Another population with a high rate of Clostridium difficile colonization are newborn babies, who are frequently (> 50%) asymptomatic carriers. Once the bacteria colonize, they produce toxins that damage the epithelial cells of the gut. This can lead to a condition known as pseudomembranous colitis.

Pseudomembranous Colitis (PMC)

PMC is the most severe _Clostridium difficile-_associated disease (CDAD). It is characterized by epithelial damage and the formation of a pseudomembrane over the colon consisting of damaged proteins, immune cells, and bacterial byproducts. PMC often damages the entire length of the colon and can lead to erosions and necrosis, as well as inflammation. This intestinal damage leads to clinical symptoms, the most prominent of which is diarrhea. The patient’s bowel movements are often soft, watery, and or mucousy in nature, and they have a strong odor. Defecation becomes more frequent, up to twenty times per day. Other signs and symptoms may include fever, abdominal pain, and increased white blood cell count. Complications of this infection include toxic megacolon and sepsis.

Diagnosis and Treatment

Diagnosis of CDAD, including PMC, is based on the combination of characteristic diarrhea and detection of the bacteria or its toxins in the stool, or observation of the formation of a pseudomembrane on the colon. The infection is treated by discontinuing the precipitating antibiotics and administering an antibiotic to which the Clostridial bacteria is susceptible, usually metronidazole or vancomycin. 15-30% of cases recur after treatment. How long is C diff contagious? As long as the stool tests positive for the presence of the bacteria. This depends on the success of treatment and whether additional courses of antibiotics are necessary. It is possible for the bacteria to colonize the colon even in the absence of symptoms.


Gerding Dale N, Johnson Stuart, “Chapter 123. Clostridium difficile–Associated Disease, Including Pseudomembranous Colitis” (Chapter). Fauci AS, Braunwald E, Kasper DL, Hauser SL, Longo DL, Jameson JL, Loscalzo J: Harrison’s Principles of Internal Medicine, 17e

Gomella LG, Haist SA, “Chapter 7. Clinical Microbiology” (Chapter). Gomella LG, Haist SA: Clinician’s Pocket Reference: The Scut Monkey, 11e