The C Diff Conundrum: Sources Harder to Pin Down, Making Control Difficult

How is Clostridioides difficile epidemiology changing? What risk factors are associated with community-acquired C. diff (CA-CDI)? How has molecular epidemiology improved our understanding of C. diff transmission? What are the potential novel sources of C. diff? 

Investigators with Duke University Medical Center certainly asked the right questions in “Novel and Emerging Sources of Clostridioides difficile Infection,” a new study published December 19 in PLOS Pathogens.  

The global answer is that infection preventionists and other infection control professionals will have their work cut out for them in the coming year. They’ll have to contend with diversity among C. diff isolates, mounting evidence that it’s often transmitted outside the hospital, and that those multiple sources of infection will put current infection control processes to the test. Coming up with the best approach will take lots of exposure-related data, coupled with whole genome sequencing. 

“With the additional issues of widespread outpatient healthcare contact, asymptomatic carriage, and long-term environmental persistence of spores, even the basic distinction between community- versus healthcare-associated CDI may become less relevant with time,” the study states.

Mathematical modeling studies suggest reducing transmission would require that patients with C. diff be placed in single rooms and the healthcare workers who care for them wear gowns and gloves. Clinical data supporting this method are missing, however. “Molecular epidemiologic studies attribute a relatively small minority of transmission events to carriers,” the study states.

It’s more of a challenge to investigate CA-CDI than healthcare-associated infections (HAIs). There aren’t even that many population-based studies on CDI incidence, say investigators. Which population is most at risk? And how does the healthcare system go about tracking it? These questions have not been answered and don’t look to be answered anytime soon. 

“One of the major issues with defining populations at risk for CA-CDI is a lack of centralized testing or surveillance,” the study states. “Because patients are able to present to urgent cares, primary care offices, emergency rooms, and hospitals, often all belonging to different healthcare networks, it is extremely difficult to determine how many cases are occurring within a particular community.”

The fact that most C. diff interventions occur within the hospital also limit what can be done about CA-CDI. It’s also unclear just how the infection travels: from the community into the hospital, the other way around, or some combination of both? Also, “even though healthcare contact is frequently associated with CA-CDI, it remains unclear if this reflects patients who are actually at elevated risk because of multiple chronic health problems or if contact with healthcare is truly what is driving the risk.”

Nursing homes and long-term care facilities seem to be breeding grounds for C. diff and may be a major source of C. diff infection in hospitals because many of the residents in those latter facilities often wind up in the hospital. 

“With the additional issues of widespread outpatient healthcare contact, asymptomatic carriage, and long-term environmental persistence of spores, even the basic distinction between community- versus healthcare-associated CDI may become less relevant with time. Given the challenges posed by current evidence of interspecies transmission and environmental reservoirs of C. difficile, future research in C. difficile prevention will require an integrative multidisciplinary approach, as exemplified by the OneHealth concept.”