title: Terminal decontamination of patient rooms using an automated mobile UV light unit.
abstract: OBJECTIVE
  To determine the ability of a mobile UV light unit to reduce bacterial contamination of environmental surfaces in patient rooms.
  
  
  METHODS
  An automated mobile UV light unit that emits UV-C light was placed in 25 patient rooms after patient discharge and operated using a 1- or 2-stage procedure. Aerobic colony counts were calculated for each of 5 standardized high-touch surfaces in the rooms before and after UV light decontamination (UVLD). Clostridium difficile spore log reductions achieved were determined using a modification of the ASTM (American Society for Testing and Materials) International E2197 quantitative disk carrier test method. In-room ozone concentrations during UVLD were measured.
  
  
  RESULTS
  For the 1-stage procedure, mean aerobic colony counts for the 5 high-touch surfaces ranged from 10.6 to 98.2 colony-forming units (CFUs) per Dey/Engley (D/E) plate before UVLD and from 0.3 to 24.0 CFUs per D/E plate after UVLD, with significant reductions for all 5 surfaces (all [Formula: see text]). Surfaces in direct line of sight were significantly more likely to yield negative culture results after UVLD than before UVLD (all [Formula: see text]). Mean C. difficile spore log reductions ranged from 1.8 to 2.9. UVLD cycle times ranged from 34.2 to 100.1 minutes. For the 2-stage procedure, mean aerobic colony counts ranged from 10.0 to 89.2 CFUs per D/E plate before UVLD and were 0 CFUs per D/E plate after UVLD, with significant reductions for all 5 high-touch surfaces. UVLD cycle times ranged from 72.1 to 146.3 minutes. In-room ozone concentrations during UVLD ranged from undetectable to 0.012 ppm.
  
  
  CONCLUSIONS
  The mobile UV-C light unit significantly reduced aerobic colony counts and C. difficile spores on contaminated surfaces in patient rooms.
authors.affiliation: Department of Medicine, Hospital of Saint Raphael, Yale University School of Medicine, New Haven, Connecticut 06511, USA. jboyce@srhs.org
authors.forename: John M
authors.initials: JM
authors.lastname: Boyce
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Havill
authors.forename: Brent A
authors.initials: BA
authors.lastname: Moore
mesh_terms: D001420:Bacteria, Aerobic / Q000302:isolation & purification*; D016360:Clostridioides difficile / Q000302:isolation & purification*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000295:instrumentation* / Q000379:methods; D004865:Equipment and Supplies, Hospital / Q000382:microbiology*; D010362:Patients' Rooms; D011446:Prospective Studies; D014466:Ultraviolet Rays