Efficacy of "sporicidal" wipes against Clostridium difficile

Hospital-acquired infections associated with Clostridium difficile cause severe morbidity and mortality. The current control of C difficile endospores with liquid sporicides might have limited efficacy in the health care environment. Sporicidal wipes might offer additional control of surface bioburden and are now increasingly used, although there is little information about their efficacy against spores in practice.

Ten wipes were tested for sporicidal efficacy using a recently developed 3-stage protocol that measures the ability of the wipe to remove microbial bioburden from a surface, the potential for microbial transfer from the wipe to other surfaces, and the sporicidal activity of the wipe. Scanning electron microscopy was used to visualize the association of spores with the wipe fibers, and light scattering was used to measure the size of spore aggregates released from the wipes.

The ability of the sporicidal wipes to remove C difficile spores from an inanimate surface ranged from 0.22 to 4.09 log(10) spores removed within 10 seconds. One wipe did not remove any spores. None of the wipes demonstrated high sporicidal activity (ie, >4 log(10) reduction) within 5 minutes of contact time, except for a control wipe soaked in 5,000-ppm sodium hypochlorite. Only one wipe demonstrated some sporicidal activity after 5 minutes, with a 1.50 and a 3.74 log(10) reduction in spore number of C difficile NCTC12727 and R20291 (ribotype 027), respectively. All but one wipe demonstrated that spores could be repeatedly transferred to other surfaces. Light-scattering data provided evidence that some wipes were able to break up spore aggregates, potentially releasing more spores onto the surface. Electron microscopy micrographs showed that spores might be loosely associated with some wipes, explaining the rapid release.

Although the use of sporicidal wipes might offer additional control of microbial burden on surfaces, current efficacy tests might be inadequate to reflect the activity of these wipes in practice. This can lead to the use of wipes that might not be appropriate for applications in the health care environment. Tighter control of labeling and appropriate efficacy tests are needed before antimicrobial wipes are released to the market.