Efficacy of continuous UV-C 222 exposure of Candida auris, methicillin-resistant Staphylococcus aureus, and T1 bacteriophage at two soil levels in hospital patient rooms

Introduction: The spread of Candida auris (C. auris), methicillin-resistant Staphylococcus aureus (MRSA) and various viruses in healthcare settings is of global concern. Far-UV-C222 reduces the concentration of microorganisms in laboratory settings and can be used directly in patient care rooms at doses safe for human eyes and skin. The effectiveness of UV-C222 inactivation of C. auris, MRSA and T1 bacteriophage (a viral surrogate) in a hospital setting was studied. Methods: A partially blinded, cross-over study was conducted of two conditions: intervention, active UV and control, no UV. C. auris, MRSA and T1 bacteriophage were inoculated and dried onto stainless steel disc carriers at two soil levels, (0.03% BSA and 5.0% CBS), and placed at 24 locations in two unoccupied, two-bed patient rooms. UV-C222 luminaires were placed behind the head of each bed and one in the bathroom for both study rooms. Simultaneous 24-h exposures for both rooms were in random order. Pathogens were processed for cultures. Results: UV-C222 doses exposing the discs ranged from a low of 5 mJ/cm2 to high 637 mJ/cm2. Under treatment conditions, MRSA showed a 1.0 log reduction in 0.03% soil, C. auris showed a 2.6 log reduction in 0.03% soil and a 1.0 log reduction in 5.0% soil and T1 bacteriophage showed a 0.6 log reduction in 0.03% soil. Conclusions: In patient rooms, continuous UV-C222 exposure showed decreased concentrations of C. auris (low and high soil), MRSA (low soil), and T1 (low soil). Studies are needed to determine benefits in occupied settings.