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Etiology of Community Acquired Clostridium
Difficile-Associated Disease

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


CDAD is no longer viewed simply as a complication of hospital antibiotic treatment. What was once known only as a hospital-acquired nosocomial infection is now emerging in the community in large numbers. The community CDAD infection rate in the United States has been reported as 7.7 cases per 100,000 persons each year (Rupnik, Wilcox & Gerding, 2009). The CDC published similar findings in December 2005 of 7.6 cases per 100,000 persons each year (CDC 2005).

CDAD has also been reported in healthy children, pregnant women, and adults with no known risk factors. In 2005, CDC researchers showed that 8 (24%) of the 22 low risk patients infected with CDAD had no direct exposure to antibiotics, the leading risk factor (Kuijper & Van Dissel, 2008). In addition, CDC researchers expressed concerns in 2008 when a surveillance report in Connecticut found a quarter of CDAD cases could not be explained by traditional risk factors.

The CDC suggested that risk factors for acquiring CDAD in the community include contact with a contaminated healthcare environment and/or transmission from an infected person. C. difficile can be transferred from a contaminated environment because the spore form of C. difficile is heat stable and able to survive harsh environments, such as the acidic human stomach and surfaces ostensibly disinfected. Since most disinfectants do not kill the spore, it is likely that C. difficile is spread between healthcare providers and patients indirectly and directly (McFee & Abdelsayed, 2009).

C. difficile can spread directly when a person touches a surface contaminated with feces and then touches a mucus membrane (Oriola, 2006). Equipment such as commodes and thermometers may be reservoirs for the bacteria. Indirect contact occurs when a health care provider spreads the bacteria through hand contact from one patient to another or contaminates a surface that is then touched by someone else (Oriola, 2006). Transmission can occur from an infected individual when a person carrying C. difficile sheds the bacteria in feces. In addition, alcohol based hand sanitizers do not kill C. difficile (McFee & Abdelsayed, 2009).

Jhung and his research team identified several human cases of CDAD caused by toxinotype V strains of C. difficile, which has been reported as a cause of epidemic disease in neonatal pigs and calves (Jhung et al., 2008). Although no study has been conducted on interspecies transmission of C. difficile, identification of the same strain of C. difficile in both humans and animals suggests a link (Jhung et al., 2008).

Transmission of C. difficile may occur in three ways. The first is exposure of humans and animals to the same environment. The second is indirect contact through contaminated produce, water or environment. Lastly, transmission can occur through consumption of products from food-producing animals (Jhung et al., 2008). Results from the study suggest toxinotype V C. difficile may cause CA-CDAD (Jhung et al., 2008).

Purpose, Method & Background >