Efficacy of relatively low-cost ultraviolet-C light devices against .

Background: Ultraviolet-C (UV-C) light devices could be useful to reduce environmental contamination with . However, variable susceptibility of strains to UV-C has been reported, and the high cost of many devices limits their use in resource-limited settings.

Objective: To evaluate the efficacy of relatively low-cost (<$15,000 purchase price) UV-C devices against strains from the 4 major phylogenetic clades.

Methods: A modification of the American Society for Testing and Materials (ASTM) standard quantitative disk carrier test method (ASTM E 2197) was used to examine and compare the effectiveness of UV-C devices against , methicillin-resistant (MRSA), and bacteriophage Phi6. Reductions of 3 log were considered effective. UV-C irradiance measurements and colorimetric indicators were used to assess UV-C output.

Results: Of 8 relatively low-cost UV-C devices, 6 met the criteria for effective decontamination of isolates from clades I and II, MRSA, and bacteriophage Phi6, including 3 room decontamination devices and 3 UV-C box devices. isolates from clades III and IV were less susceptible to UV-C than clade I and II isolates; 1 relatively low-cost room decontamination device and 2 enclosed box devices met the criteria for effective decontamination of clade III and IV isolates. UV-C irradiance measurements and colorimetric indicator results were consistent with microorganism reductions.

Conclusions: Some relatively low-cost UV-C light technologies are effective against including isolates from clades III and IV with reduced UV-C susceptibility. Studies are needed to evaluate the effectiveness of UV-C devices in clinical settings.