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By Kelly M. Pyrek
Clostridioides difficile: Experts Tackle the Tough Issues Related to Testing & Transmission Prevention
By Kelly M. Pyrek
In the December 2025 SHEA Town Hall,“ Cracking C. diff: Evidence-based Approaches & Real-World Impact,” panelists tackled the hard questions related to addressing one of healthcare’ s most formidable foes.
Erica Shenoy, MD, PhD, chief of infection control at Mass General Brigham and associate professor at Harvard Medical School kicked off the town hall by introducing three important papers published since the multi-society Compendium was released.
“ The first study addressed environmental and healthcare personnel sampling, so thinking beyond the patient in terms of where C. diff may be lurking and be transmitted in healthcare facilities,” Shenoy said.“ The second paper looked at genomic surveillance and carriage, and the third one discussed AI, infection prevention and stewardship.” Let’ s review the first study more closely. Acknowledging that control of C. diff is challenging due to spore viability on surfaces, Keegan, et al.( 2025) sought to quantify transmission of C. difficile within healthcare facilities and evaluate the roles of environmental surfaces and healthcare personnel( HCP)’ s hands in C. difficile transmission. The authors conducted a 13-week longitudinal, observational study in two intensive care units( ICUs) with daily culture-based sampling of patient body sites, room environmental surfaces, HCP hands, and shared environmental surfaces. Both toxigenic and nontoxigenic C. difficile strains were selected for whole genome sequencing and included in the analysis. Clusters were defined as isolates with two or fewer single nucleotide variants between them. Of the 278 unique ICU admissions, 177 patients consented to body-site sampling. Along with these, environment surfaces and HCP hands were sampled daily for all occupied rooms, leading to 7,000 total samples. Sampling patients, their environment, and HCP hands revealed that nearly 8 percent of all patients had C. difficile linked to other admissions and 57 percent of transmission clusters bridged non-overlapping patient-stays. Including environmental surfaces and HCP hands, a 3.6-fold higher C. difficile movement was identified than with patient sampling alone, highlighting environmental surfaces as reservoirs.
Related to assessment of C. difficile importation and acquisition, the authors note,“ Nine patients met the criteria for assessing acquisition( eight patients were excluded for importing C difficile: two imported toxigenic and five nontoxigenic). Only one patient was found to have acquired toxigenic C difficile. Three other patients did not meet the criteria due to no sampling on admission, but nontoxigenic C. difficile was recovered in later samples. Although body sites were not sampled on admission for these patients, C. difficile was not recovered for multiple days of room environment or HCP hands samples before recovering the first patient isolate. We consider these potential acquisition events. By including patient room surfaces and HCP hands, we were able to characterize the timing of contamination with respect to patient colonization. We found C. difficile was recovered from room surfaces and HCP hand samples a mean of 0.8( 1.64) days and 1.5( 2.08) days, respectively, after the first C. difficile isolate was recovered from the occupying patient.”
“ These authors conducted an incredible amount of sampling,” commented Shenoy.“ They did daily culture-based sampling of patient body sites, environmental surfaces that patients or healthcare personnel would touch, and they sampled the hands of healthcare personnel upon exit of the room or prior to hand hygiene or glove removal. They conducted whole genome sequencing of both toxigenic and non-toxigenic C. diff strains, so they were looking at transmission clusters based on genomic relatedness and they defined this as any pair or group of isolates that were linked from different occupants. They created a‘ heat map’ of sorts in terms of where they were finding C. diff. It’ s not surprising that on the patient, they’ re identifying C. diff in the perianal region or stool sampling in the zone closest to the patient in the patient room environment. And then, of course, they are finding it on the hands of healthcare personnel. I thought it was interesting that they didn’ t find any C. diff among the shared equipment in the supply cart. Overall, of the 7,000 samples they got 178 C. diff isolates and a large portion were non-toxigenic, finding equally from patients
12 • www. healthcarehygienemagazine. com • jan-feb 2026