title: Sorting through the wealth of options: comparative evaluation of two ultraviolet disinfection systems.
abstract: 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.
  
  
  RESULTS
  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 ∼ 3 log10CFU/cm2, MRSA by>4 log10CFU/cm2, and VRE by >5 log10CFU/cm2. 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 log10CFU/cm2 for MRSA and VRE and <2 log10CFU/cm2 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 log10CFU/cm2 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.
authors.affiliation: Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, United States of America.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Nerandzic
authors.affiliation: STERIS Corporation, Healthcare Group, Mentor, Ohio, United States of America.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Fisher
authors.affiliation: Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, United States of America; Geriatric Research, Education and Clinical Center, Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, United States of America.
authors.forename: Curtis J
authors.initials: CJ
authors.lastname: Donskey
mesh_terms: D016360:Clostridioides difficile / Q000528:radiation effects*; D004203:Disinfection / Q000295:instrumentation* / Q000379:methods; D004307:Dose-Response Relationship, Radiation; D055624:Methicillin-Resistant Staphylococcus aureus / Q000528:radiation effects*; D013045:Species Specificity; D013997:Time Factors; D014466:Ultraviolet Rays; D065507:Vancomycin-Resistant Enterococci / Q000528:radiation effects*