and healthcare personnel hands, the rooms, and then from a shared environmental surface. The prevalence was about 7 percent of environmental surfaces. They looked at the acquisition for both toxigenic and then overall acquisition of C. diff in patient populations. What I think is the big take-home message of this paper is that if you only look at the patient samples, you’ re going to be missing transmission events. So, 7.77 percent of admission patients had C. diff that was genetically linked to another occupant’ s stay on the same ward. There were six transmission clusters that were identified that involved either environmental surfaces or healthcare personnel hands, which led to the identification of almost four times as many clusters as if they had been only focused on patient sampling. Further, only two patients were identified during this time period as having C. diff, so that the majority of the isolates that they recovered were really under what they described as the radar of traditional surveillance.”
As the study authors concluded,“ These results challenge the idea that nosocomial transmission is not a primary source of acquisition and underscore the importance of hand hygiene and environmental decontamination. This study reinforces the need to include environmental surfaces and HCP hands in future work characterizing the burden of nosocomial transmission. Understanding the transmission pathways of C. difficile within healthcare facilities, particularly the roles of environmental surfaces and HCP hands, is critical to improving infection control measures.”
In the second study, Miles-Jay( 2023) conducted admission and daily longitudinal culture-based screening for C. difficile in an ICU over nine months and performed whole-genome sequencing on all recovered isolates. The authors note,“ Despite a high burden of carriage, with 9.3 percent of admissions having toxigenic C. difficile detected in at least one sample, only 1 percent of patients culturing negative on admission to the unit acquired C. difficile via cross-transmission. While patients who carried toxigenic C. difficile on admission posed minimal risk to others, they themselves had a 24-times greater risk for developing a healthcare-onset C. difficile infection than noncarriers. Together, these findings suggest that current infection prevention practices can be effective in preventing nosocomial cross-transmission of C. difficile, and that decreasing C. difficile infections in hospitals further will require interventions targeting the transition from asymptomatic carriage to infection.”
As we know, asymptomatic carriage is of critical concern. The authors explain,“ Asymptomatic carriers of C. difficile, defined as persons who carry the C. difficile organism without clinical symptoms indicative of C. difficile infection, could be underappreciated reservoirs of C. difficile within healthcare settings. Asymptomatic carriers are more common in the hospital than symptomatic patients; as many as 29 percent of high-acuity patients in acute-care settings have been shown to carry C. difficile asymptomatically. The risk of transmission from unidentified, asymptomatic carriers may also be higher than from symptomatic patients because carriers can shed spores into the environment, yet they are usually not under the same contact precautions and their rooms may not undergo the same environmental cleaning procedures as patients with CDI. Additionally, recent data indicated that carriers of C. difficile are at a higher risk of developing CDI than noncarriers. However, the risk that asymptomatic carriers of C. difficile pose, both to other patients and to themselves, is incompletely characterized due to a lack of available data collected via detailed longitudinal sampling and high-resolution typing. Thus, the utility of screening patients for C. difficile on admission— both to prevent transmission and infection— remains under debate and professional medical societies have not issued recommendations regarding screening patients for asymptomatic carriage of C. difficile.”
“ In this paper they were trying to understand what we can learn if we look over time at C. diff carriage transmission and the risk of developing infections,” Shenoy explained.“ For nine months they collected rectal swabs and stool samples from patients; they cultured them for toxigenic and non-toxigenic C. diff and they conducted whole genome sequencing. They were looking at importation, meaning patients arriving into that ICU with C. diff already and also looking at the association between arriving at the hospital with C. diff and it developing into infection. There were about 1,200 admissions among 1,100 patients; toxigenic C. diff acquisition with 544 admissions and for healthcare onset C. diff with 934 admissions and 830 patients qualified. Overall screening preference was 9.3 percent. They found 1.6 acquisitions per 100 patient days, and only 32 of the cases they identified could be linked back to an importation event. The main take-home message of this study is the hazard ratio of the risk of developing C. diff infection from those carriers.”
Shenoy emphasized some key caveats associated with these studies.“ In the first study, they were looking at patients, healthcare worker hands and the environment; in the second study, we’ re only looking at patient screens. So, to the extent that the environment and healthcare workers’ hands are contributing to transmission, that would not be visible in this study. The other point is that the cleaning agent that they used was a sporicidal and they used that daily in this ICU and at the time of discharge. Other studies have looked at using a sporicidal agent as well as optimized cleaning protocols and that had been associated with reduction in C. diff. So, perhaps the very little amount of transmission that they observed could have been due to some of the other interventions that were in place.”
In the third study, Tang, et al.( 2025) evaluated the association of an AI-guided infection prevention bundle with CDI incidence in a hospital setting. A previously validated institution-specific AI model for CDI risk prediction was integrated into clinical workflows at the study site. The model was used to guide infection prevention practices for reducing pathogen exposure through enhanced hand hygiene and reducing host susceptibility through antimicrobial stewardship. Pre-AI and post-AI samples included 39,046( 21,645 [ 55.4 %] female; median [ IQR ] age, 58 [ 36-70 ] years) and 40,515( 22,575 [ 55.7 %] female; median [ IQR ] age, 58 [ 37-70 ]
SHEA Town Hall panelists:
Erica Shenoy
Larry Kociolek
Matt Linam
Marci Drees
Trish Perl
jan-feb 2026 • www. healthcarehygienemagazine. com •
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