Sorting through the Wealth of Options: Comparative Evaluation of Two Ultraviolet Disinfection Systems

Background: Environmental surfaces play an important role in the transmission of healthcare-associated pathogens. Because environmental cleaning is often suboptimal, there is a growing demand for safe, rapid, and automated disinfection technologies, which has lead to a wealth of novel disinfection options available on the market. Specifically, automated ultraviolet-C (UV-C) devices have grown in number due to the documented efficacy of UV-C for reducing healthcare-acquired pathogens in hospital rooms. Here, we assessed and compared the impact of pathogen concentration, organic load, distance, and radiant dose on the killing efficacy of two analogous UV-C devices. Principal Findings: The devices performed equivalently for each impact factor assessed. Irradiation delivered for 41 minutes at 4 feet from the devices consistently reduced C. difficile spores by similar to 3 log(10)CFU/cm(2), MRSA by>4 log(10)CFU/cm(2), and VRE by >5 log(10)CFU/cm(2). Pathogen concentration did not significantly impact the killing efficacy of the devices. However, both a light and heavy organic load had a significant negative impacted on the killing efficacy of the devices. Additionally, increasing the distance to 10 feet from the devices reduced the killing efficacy to <= 3 log(10)CFU/cm(2) for MRSA and VRE and <2 log(10)CFU/cm(2) for C. difficile spores. Delivery of reduced timed doses of irradiation particularly impacted the ability of the devices to kill C. difficile spores. MRSA and VRE were reduced by >3 log(10)CFU/cm(2) after only 10 minutes of irradiation, while C. difficile spores required 40 minutes of irradiation to achieve a similar reduction. Conclusions: The UV-C devices were equally effective for killing C. difficile spores, MRSA, and VRE. While neither device would be recommended as a stand-alone disinfection procedure, either device would be a useful adjunctive measure to routine cleaning in healthcare facilities.