Discoveries About C. diff Underscore That What Happens Outside Hospitals Doesn’t Always Stay Outside Hospitals


Hospital administrators and infection preventionists have to contend with diversity among C. diff isolates.

Andrew D. Racine, MD, senior vice president and chief medical officer at Montefiore Medical Center, did the math when Infection Control Today® (ICT) asked whether he was contemplating changing his facility’s approach to combatting Clostridioides difficile (C. diff) after the results of a recent study found that 10% of patients with the infection had contracted it outside of the hospital. “If 10% of the people coming to your institution are carriers of C. diff, that means that 90% are not,” said Racine, when asked whether universal screening would help ward off the infection. “So, you would be doing an awful lot of tests that would essentially be negative.” 

Racine quickly adds that the research conducted recently at Montefiore does point “us in a direction where we might want to think about doing some further studies to figure out who should be targeted for testing. Clearly, there are some folks who come who have a much higher likelihood of being carriers. We need to find out what are the characteristics of those folks. Because then it would make sense to narrow testing for those.” 

Published in Infection Control and Hospital Epidemiology,the study made headlines because it reported that C. diff, which strikes about 450,000 Americans a year, killing nearly 30,000 of them, isn’t always acquired in the hospital. Sometimes it just walks right in. 

Investigators looked at data from about 220 patients who showed no symptoms of C. diff who were admitted to Montefiore (located in the Bronx) between July 2017 and March 2018. The patients were given perirectal swabs within 24 hours of admission and were then followed for 6 months. Upon admission, 21 patients were identified as carriers. Within 6 months, 38% of the carriers progressed to symptomatic C. diff infection compared with just 2% of the non-carriers. 

Although prospectively identifying carriers is not a recommended strategy in everyday situations, the US Centers for Disease Control and Prevention (CDC) does call it a supplemental interventionto spur rapid evaluation and treatment of patients suspected of having C. diff when there’s concern about a possible outbreak, according to Sarah Baron, MD, the study’s lead author and an assistant professor of medicine at Montefiore. “It is possible that more and more hospitals will consider identifying carriers in their highest risk populations to protect the individual patient and the patients around them from acquiring symptoms of the disease,” Baron told ICT. “We hope that this [study] will actually help to fuel the conversation about enhanced infection control practices to prevent C. difficile spread.” 

Those enhanced practices would in part target the many patients who carry C. difficile, but don’t yet exhibit symptoms. “Many of these patients may go on to develop the disease, and frontline staff will require even more support from administration in order to prevent or avoid it,” Baron said. Sounds great, except that hospital administrators must take into account the amount of time, effort, and money required for such an undertaking as opposed to what else those resources could be used for “that would be perhaps more valuable from the standpoint of quality or safety,” Racine said. 

Meanwhile, in a study published in PLOS Pathogens,investigators with Duke University Medical Center pointed out that C. diff has become more difficult to pin down and seconded Baron’s conclusion that it’s often transmitted outside the hospital. Infection control professionals have to contend with diversity among C. diff isolates, and multiple sources of infection that often 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 wide- spread outpatient healthcare contact, asymptomatic carriage, and long-term environmental persistence of spores, even the basic distinction between com- munity- versus healthcare-associated [C. diff] may become less relevant with time,” thePLOS Pathogens study states. 

The research also points to a lack of centralized testing or surveillance. “Because patients are able to present to urgent cares, primary care offices, emergency rooms, and hospitals, often all belonging to different health-care networks, it is extremely difficult to determine how many cases are occurring within a particular community,” the PLOS Pathogens study states. 

What Racine found particularly interesting about the study at Montefiore was the fact that fewer people admitted from skilled nursing facilities (SNFs) were C. diff carriers than what’s been previously measured. 

“There have been other studies that have indicated that up to 50% of patients coming from skilled nursing facilities may actually be carriers and that’s 5 times what our estimate was,” says Racine. “Part of the lessons from doing these kinds of studies-and this is often something that the researchers anticipate but that readers may not-is that they raise as many questions as they answer.” 

Baron said that “1 question that our research could not answer was what to do next to prevent the progression of C. difficile. We do hope that our work on identification of carriers will encourage work on intensified antibiotic stewardship interventions, enhanced cleaning of all patient areas, and identification of at-risk patients as possible next steps.” 

Racine is proud of Montefiore’s “robust” antibiotic stewardship program, in which infection preventionists play a crucial role. 

“We are very, very cognizant that antibiotics-although they are powerful, therapeutics-also have downsides associated with them. What oftentimes is associated with the change from just being an asymptomatic carrier to actually being symptomatic with C. diff is the exposure to antibiotics,” he said. “We have an obligation as hospital administrators to be vigilant about antibiotic use.” 

But IPs have a lot of duties, not just antibiotic stewardship. “They help us in monitoring infections in a variety of different circumstances throughout the hospital,” said Racine. 

C. diff also requires knowing when to isolate infected patients and also, as Baron mentioned, how best to disinfect hospital rooms. Racine said that “those are resources that are very well spent because they not only prevent the dissemination of this condition, but they prevent the dissemination of all other kinds of infections. And one of the risks of coming into a hospital is that you are aggregating lots and lots of people with lots and lots of infections in a single place.” 

It’s also crucial to pay close attention to how “it is that we cohort patients with particular infections,” said Racine. 

The PLOS Pathogens study stated that some mathematical models suggest that 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 PLOS Pathogens study states. 

Mathematical models? Doffing? Environmental services? Food preparation? Racine iterates that infection control should permeate entire facilities, with everyone participating. 

“We have teams of folks who are responsible for that kind of training,” he said. “We include input from our infection preventionists, hospital epidemiologists, infectious disease physicians. It’s a real combined effort so that folks who are on the frontline in facilities or in food handling or any of those things have input from experts that is going to be most helpful for them.” 

Continuous input, he adds. 

“You don’t just expose this information to them once and that’s the end of it,” Racine said. “We have to maintain a constant state of readiness and preparation for these things. And that means when people first come to the institution as part of their orientation, and it also means exposure to this information over the time that they’re working here.” 

Baron sees the results. She said that she hopes her study “highlights all of the amazing work that our infection prevention and control, environmental services, and antimicrobial stewardship teams do every day to keep our patients as safe as possible.” 


1. Baron SW, Ostrowsky, BE, et al. Screening of Clostridioides difficile carriers in an urban academic medical center: Understanding implications of disease. Infect Control Hosp. Epidemiol. 2019 Dec 11:1-5. doi: 10.1017/ice.2019.309
2. Centers for Disease Control and Prevention. Strategies to prevent Clostridioides difficile infection in acute care facilities. CDC website. Accessed January 2020.
3. Turner NA, Smith BA, Lewis SS (2019) Novel and emerging sources of Clostridioides difficile infection. PLoS Pathog 15(12): e1008125.

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