Work underscores C. difficile infection is not a common hospital transmission

CAMBRIDGE, MA – New research from MIT suggests the risk of becoming colonized by Clostridium difficile (C. difficile) increases immediately following gastrointestinal (GI) disturbances that result in diarrhea. Once widely considered an antibiotic and hospital associated pathogen, recent research into C. difficile has shown the infection is more frequently acquired outside of hospitals. Now, a team of researchers in MIT’s Department of Civil and Environmental Engineering (CEE) have shown that GI disturbances, such as those caused by food poisoning and laxative abuse, trigger susceptibility to colonization by C. difficile, and carriers remain C. difficile positive for a year or longer.

“Our work helps show why the hospital and antibiotic association of C. difficile infections is an over-simplification of the risks and transmission patterns, and helps reconcile a lot of the observations that have followed the more recent revelation that transmission within hospitals is uncommon,” said David VanInsberghe, PhD, lead author of the study, ‘Diarrheal events can trigger long-term Clostridium difficile colonization with recurrent blooms’ in Nature Microbiology, published on February 10.

The researchers analyzed human gut microbiome time series studies conducted on individuals who had diarrhea illnesses and were not treated with antibiotics. Observing the colonization of C. difficile soon after the illnesses were acquired, they tested this association directly by feeding mice increasing quantities of laxatives while exposing them to non-pathogenic C. difficile spores. Their results suggest that GI disturbances create a window of susceptibility to C. difficile colonization during recovery.

Further, the researchers found that carriers shed C. difficile in highly variable amounts day-to-day; the number of C. difficile cells shed in a carrier’s stool can increase by over 1,000 times in one day. These recurrent blooms likely influence the transmissibility of C. difficile outside of hospitals and their unpredictability questions the reliability of single time-point diagnostics for detecting carriers.

“In our study, two of the people we followed with high temporal resolution became carriers outside of the hospital,” said VanInsberghe, now a post-doctoral researcher in the Department of Pathology at Emory University. “The observations we made from their data helped us understand how people become susceptible to colonization and what the short- and long-term patterns in C. difficile abundance in carriers look like. Those patterns told us a lot about how C. difficile can spread between people outside of hospitals.”

The research team included Joseph A. Elsherbini, MIT graduate student; Bernard Varian, MIT’s Division of Comparative Medicine; Theofilos Poutahidis Department of Pathology, College of Veterinary Medicine, Aristotle University, Greece; Susan Erdman, MIT’s Division of Comparative Medicine; Martin Polz, visiting professor, MIT’s Parsons Laboratory for Environmental Science and Engineering.