Study challenges basic assumptions about C. diff transmission

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A new study contradicts widely held assumptions about how Clostridium difficile infection occurs, which may lead long-term care providers to step up control measures.

Most C. diff infection control protocols are based on a belief that symptomatic patients in healthcare settings are the primary sources of transmission. However, researchers in the United Kingdom have concluded this may not be true, based on genetic analysis of samples obtained from 1,223 people in Oxfordshire between 2007-2011.

After conducing whole genome sequencing, the researchers discovered that 45% of cases were genetically distinct from all previous cases. This suggests that “genetically diverse” sources — not just symptomatic patients — play “a major part” in C. diff transmission, according to the findings published yesterday in The New England Journal of Medicine.

It's still unclear what those sources are, noted Curtis J. Donskey, M.D., of the VA Medical Center in Cleveland. Donskey wrote an accompanying editorial in the NEJM, and spoke to McKnight's about the study's implications for long-term care providers.

“The strains might be coming from other sources in the hospital or potentially from nursing homes, or asymptomatic carriers in hospitals or the community,” Donskey said.

Current infection control measures should be kept in place in nursing homes, and the study also reinforces how important antibiotic stewardship is, Donskey said. Given the apparently varied sources of C. diff infection, the best defense is to use antibiotics wisely, so as not to become susceptible.

“We need to broaden our studies to understand if C. diff is being acquired from other human sources, food, water, etc.,” Donskey told McKnight's. “We don't know what the sources are.”