Evaluation of the Efficacy of UV-C Radiation in Eliminating Clostridioides difficile from Touch Surfaces Under Laboratory Conditions

Abstract

Clostridioides difficile (CD) is a Gram-positive, spore-forming anaerobic bacterium, usually transmitted through the fecal-oral route, that can result from direct person-to-person contact, exposure to contaminated environmental surfaces, or contact with the hands of colonized healthcare personnel. An increased number of infections, especially healthcare-associated, with this etiology has been observed in most countries. As a spore-forming organism, CD is resistant to alcohol formulations and is a challenge for chemical disinfection. The solution could be the supplementation of traditional disinfection with non-touch techniques, such as UV-C radiation. The adoption of UV-C as a supplementary disinfection method in hospitals has significantly increased since the COVID-19 pandemic. However, there are no current guidelines concerning the use of UV-C disinfection in hospitals. The aim of this study was to evaluate the effectiveness of UV-C irradiation in inactivating Clostridioides difficile from different types of surfaces in hospital settings. The study was based on laboratory tests evaluating the efficacy in eliminating three different C. difficile strains on carriers made of plastic, metal and glass after 10 min exposure to UV-C (wavelength, 253.7 nm). We observed a wide range of reductions in the C. difficile suspensions depending on the density of the carrier contamination, type of carrier, strains and the location of the carrier. The percentage reductions ranged from 0 to 100%, but the best results were observed for glass, with lower initial suspension density and carrier placement on a door frame. Statistically significant differences were only seen in different suspension densities. Our experiment was a continuation of the tests done for non-sporing bacteria and C. auris, and there were some interesting differences in C. difficile reflecting its biology, especially its sensitivity to an aerobic atmosphere during the sample drying. Although the elimination of C. difficile by UV-C radiation was confirmed in our experiment, it was lower than in the case of non-spore-forming bacteria. Thus, this method may be used in healthcare settings (hospitals) for improving environmental safety and preventing C. difficile spreading.

Keywords: C. difficile; UV-C disinfection; hospital infections.

Figure 1

Plan of the room where the effectiveness of surface disinfection by the UV-C method using OCTA robots was tested.

Figure 2

Differences in percentage of reduction across different density categories. Individual data points are shown with jitter. A—density of bacterial suspension 10⁸ CFU/mL, B—density of bacterial suspension 10⁷ CFU/mL.

Figure 3

Differences in percentage of reduction depending on the type of carrier. Individual data points are shown with jitter.

Figure 4

Differences in percentage of reduction depending on the C. difficile strain. Individual data points are shown with jitter.

Figure 5

Differences in percentage of reduction depending on the locations of the carriers. Individual data points are shown with jitter. Legend: 1—table top, 2—a desk top, 3—floor, 4—door frame, 5—Refrigerator/shelf.