A longitudinal genomic screening for Clostridioides difficile (C. difficile) among admitted patients in intensive care units uncovered a hitherto hidden aspect of infection control: asymptomatic carriers pose a greater risk of developing infections themselves, than transmitting these infections to other patients. This discovery, while going against the common preference of hospitals to minimize their record of such metrics, brings forth vital information that could remodel strategies aimed at reducing Clostridioides difficile infection (CDI), currently the leading healthcare-associated infection in the United States.
Current methodologies for infection prevention have shown limited success due to the difficulty in accounting for asymptomatically carrying patients, who can silently act as reservoirs of infection and transmit the disease silently. This research, which involved admission and daily screenings for C. difficile over a span of nine months in an ICU, is a step towards overcoming this problem.
The research team, led by Dr. Arianna Miles-Jay from the Department of Microbiology and Immunology, University of Michigan Medical School, performed whole-genome sequencing on all recovered isolates, and also conducted epidemiological tracking of C. difficile importation and acquisition during hospital stays. Their work resulted in over 400 individual instances of C. difficile isolates, most from patients with high exposure to antibiotics and admitted through the emergency medicine department. Multiple strains were often found in a single patient.
Interestingly, the investigators debunked the theory that presence of non-toxigenic C. difficile strains could ward off the acquisition of toxigenic strains. On the contrary, they proposed the existence of non-toxigenic strains might be signaling a gut environment prone to toxigenic C. difficile acquisition. Despite the high carriage burden (9.3% of admissions had toxigenic C. difficile detected), only 1% of patients with negative culture on admission subsequently acquired C. difficile via cross-transmission.
The team iterated that while patients carrying toxigenic C. difficile on admission were not a significant risk to others, they themselves had a 24 times higher risk for developing a healthcare-acquired C. difficile infection. This calls for a reformation in current infection prevention strategies, highlighting the need to focus on the transition from asymptomatic carriage to infection, and not only on nosocomial cross-transmission of C. difficile.
Source: https://www.contagionlive.com/view/screening-for-asymptomatic-c-difficile-in-icu-admissions-reveals-risk-for-infections