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Etiology of Community Acquired Clostridium
Difficile-Associated Disease

By: Shannan Sherman and Dr. Pamela Ark | Mentor: Dr. Pamela Ark


Clostridium difficile (C. difficile) is a gram positive, spore-forming toxin producing anaerobic rod bacteria that results in millions of deaths per year (McFee & Abdelsayed, 2009). Clostridium difficile-associated disease (CDAD) is caused by the toxins released from the bacteria C. difficile. The two toxins the bacteria produce are toxin A and toxin B, which cause colonic dysfunction and death (CDC, 2008). Symptoms of CDAD include watery diarrhea, fever, loss of appetite, nausea and abdominal pain (CDC, 2007). The clinical outcomes of CDAD range from asymptomatic colonization to mild diarrhea and more serious diseases such as pseudomembranous colitis, toxic megacolon, bowel perforation, sepsis, shock and death (Rupnik, Wilcox & Gerding, 2009).

Risk factors associated with CDAD are increased age, recent hospital admission, and previous use of antibiotics and conditions that may affect colonic flora (Kuijper & Van Dissel, 2008). Antibiotics are the primary risk factor for CDAD because the antibiotics disrupt the normal bowel flora and allow for C. difficile overgrowth. Antibiotics associated with higher risk for CDAD are clindamycin, cephalosporins, and floroquinolones (McFee & Abdelsayed, 2009). Although most cases of CDAD are associated with risk factors, many cases of community acquired CDAD (CA-CDAD) are not. (Kuijper & Van Dissel, 2008).

The Centers for Disease Control and Prevention (CDC) differentiate CA-CDAD from hospital acquired-CDAD CA-CDAD is diagnosed when the onset of symptoms occurred while the patient was outside a healthcare facility and the patient had not been discharged from a healthcare facility within twelve weeks prior to symptom onset; or the onset of symptoms occurred within 48 hours after admission to a healthcare facility and the patient had no prior stay in a healthcare facility within twelve weeks before symptoms onset (CDC, 2007).

In 2000, a new strain of C. difficile was identified as North American pulsed-field 1 (NAP1). This new strain produces an extra toxin and increased amounts of toxin A and B. In addition, NAP1 causes increased morbidity and mortality. Studies suggest that NAP1 may be the most common strain in the community cases (CDC, 2008).

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