Clostridium difficile is an endemic anaerobic gram-positive bacillus that is part of the normal gastrointestinal flora. It has acquired importance because of its role in the development of pseudomembranous enterocolitis following the use of antibiotics. In these cases, fever and diarrhea develop 1–14 days after the start of antibiotic therapy. The diarrhea occasionally becomes bloody and typically contains a cytopathic toxin that is elaborated by C difficile.
Enzyme immunoassay and PCR tests allow for rapid detection. The most frequently implicated antibiotics include clindamycin, ampicillin, chloramphenicol, tetracycline, erythromycin, and the cephalosporins. New, hypervirulent strains of C difficile have emerged recently in the United States, Europe, and Japan. Initial treatment includes discontinuing the causative antibiotic and administering metronidazole for 10 days. Vancomycin should be used only in patients who cannot tolerate or have not responded to metronidazole, or in situations in which metronidazole use is contraindicated, such as during the first trimester of pregnancy. Bezlotoxumab, a human monoclonal antibody against C difficile toxin B, is associated with a rate of recurrent infection that is 38% lower than that associated with standard-of-care therapy alone.
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Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.