More than 400,000 cases of Clostridioides difficile infection (CDI) and nearly 30,000 deaths from C. difficile-associated diarrhea are reported annually in the US. In the past, efforts to limit transmission have focused on isolating patients with symptomatic C. difficile-associated diarrhea. Sarah Baron, MD, MS, and colleagues came to new hypothesis while witnessing the infection in hospitals. For a study published in Infection Control & Hospital Epidemiology, the researchers sought to better understand the transmission and prevalence of C. difficile through determining the number of asymptomatic patients admitted to the hospital already carrying C. difficile and how frequently these patients develop symptomatic infections.

The study team conducted a prospective cohort study, sampling patients at a large urban hospital between 2017 and 2018. To confirm indications from previous studies that nursing facility residents are at an increased risk of C. difficile infection, Dr. Baron and colleagues selected participants from the community and patients from nursing facilities at a 1:4 ratio. Participants were given a noninvasive perirectal swabbing within 24 hours of hospital admission, with specimens processed the same day, incubating the specimen in a meat broth for 48-72 hours, and then repeating the tests. All participants did not report diarrhea and were followed for 6 months or until death.

The prevalence of asymptomatic C. difficile carriers was 9.6%, including 10.2% of nursing facility and 7.7% of community patients. Prevalence of C. difficile detection was increased in the 45% of patients who had soiled test swabs (odds ratio 2.7), when compare with those who did not. Among carriers identified during testing, 38.1% were subsequently diagnosed with symptomatic CDI within 6 months, compared with only 2.0% of non-carriers.

“I cannot stress the finding enough,” emphasizes Dr. Baron, “that patients who carry C. difficile are much more likely to proceed to symptomatic C. difficile infection. This could change how we consider identifying carriers, protecting non-carriers through isolation and environmental cleaning, and protecting carriers from symptomatic infections via antimicrobial stewardship.”