Efficacy of UV-C 254 nm Light and a Sporicidal Surface Disinfectant in Inactivating Spores from Clostridioides difficile Ribotypes In Vitro

Clostridioides difficile is widely recognised as one of the most common causes of healthcare-associated C. difficile infections due to the ability of spores to survive for prolonged periods in the hospital environment. This study aimed to evaluate the efficacy of UV-C 254 nm light in the inactivation of the spores of different C. difficile ribotypes on brain heart infusion (BHI) agar plates or in phosphate-buffered saline (PBS) with varying spore densities. Furthermore, the effectiveness of a sporicidal surface disinfectant against C. difficile spores was determined on different surfaces. Spore suspensions of different C. difficile strains in the range of 105-107 colony-forming units (CFUs) mL-1 were inoculated on BHI agar plates or in PBS and exposed to UV-C light for up to 30 min. Additionally, a spore suspension of 103-105 CFUs was spread over a 1 cm2 test area on different surfaces, and sporicidal surface wipes were used according to the manufacturer's instructions. The findings demonstrated that spores of C. difficile ribotypes exhibited a complete reduction in log10 CFU on BHI agar plates and PBS following 20 min of exposure to a UV-C dose of 2208 mJ cm-2. The surface wipes with sporicidal properties demonstrated efficacy in reducing the number of C. difficile spores on the Formica, stainless steel, and plastic surfaces by 2.03-3.53 log10. The present study demonstrates that moist surfaces or liquids can enhance the efficacy of UV-C treatment in reducing C. difficile spores. This approach may be applicable to the surfaces of healthcare facilities and to water disinfection systems.