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Clostridium difficile Infections: Diagnosis, Treatment, and Prevention

Slide: 13 of 33

Introduction: C.difficile Etiology

Clostridium difficile is a Gram-positive, spore-forming, anaerobic bacterium that can cause CDI when a toxigenic strain is ingested by a susceptible person. In order for CDI to develop, a person must be infected with a strain of C. difficile capable of making toxin in the person’s colon. Toxigenic strains are those that make toxin B (a cytotoxin), with or without toxin A (an enterotoxin). Approximately 1–2 percent of healthy individuals are colonized with C. difficile. If these people have usual, healthy colonic flora, the risk of developing CDI is very low. There is a small risk of CDI if the colon flora becomes disturbed, commonly through antibiotic use, if the person is colonized with a toxigenic strain. The immune status of the patient also contributes to the risk of developing CDI and the experienced severity. Other risk factors include increasing age, female gender, comorbidities, gastrointestinal procedures, and use of gastric acid suppression medications. Risk profiles for recurrent CDI are similar.

In addition to institutional care environments, C. difficile is also common in the community, being easily isolated from soil and water samples. New, more virulent strains have emerged since 2000. Characteristics associated with hypervirulent strains can include increased toxin production, an additional binary toxin, hypersporulation, and high-level resistance to fluoroquinolone antibiotics. These new strains affect a wider population, often people with a lack of established risk factors for CDI and include children, pregnant women, and other healthy adults.