Infection Control & Hospital Epidemiology (2018), 39, 1250–1253 doi:10.1017/ice.2018.200
Concise Communication
Antimicrobial activity of a continuous visible light disinfection system
William A. Rutala PhD, MPH1,2, Hajime Kanamori MD, PhD, MPH1,2,3, Maria F. Gergen MT (ASCP)1,2, Emily E. Sickbert-Bennett PhD1,2, Daniel J. Sexton MD4, Deverick J. Anderson MD, MPH4, Jeffrey Laux PhD5,
David J. Weber MD, MPH1,2 and the CDC Prevention Epicenters Program 1Hospital Epidemiology, University of North Carolina Hospitals, Chapel Hill, North Carolina, 2Division of Infectious Diseases, UNC School of Medicine, Chapel Hill, North Carolina, 3Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan, 4Duke Infection Control Outreach Network, Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina and 5North Carolina Translational and Clinical Sciences Institute, North Carolina
Abstract
We evaluated the ability of high-intensity visible violet light with a peak output of 405 nm to kill epidemiologically important pathogens. The high irradiant light significantly reduced both vegetative bacteria and spores at some time points over a 72-hour exposure period. (Received 21 March 2018; accepted 14 July 2018; electronically published August 30, 2018)
Over the last decade, substantial scientific evidence suggests that the hospital environment is an important source of organisms that, when transmitted, can cause healthcare-associated infections for several reasons.1 First, the hospital environment is commonly contaminated with epidemiologically important healthcare pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), multidrug- resistant (MDR) Acinetobacter, and Clostridium difficile.1,2 These pathogens share the following general characteristics: (1) devices and surfaces in the patient room are frequently contaminated; (2) an ability to survive for prolonged periods of time on environ- mental surfaces (eg, days to months); and (3) contact with sur- faces contaminated with these results in hand or glove contamination, which may be transferred to patients. Finally, room disinfection reduces contamination with these organ- isms.1–3 Second, standard cleaning and disinfection methods are inadequate in most, if not all, hospitals. On average, only 50% of surfaces in hospital rooms are cleaned between patients.4 As a result, patients admitted to the rooms previously occupied by patients with MDR organisms are at a 39%–353% increased risk of subsequent infection (a 120% increased risk on average).4 An overhead light fixture technology, which continuously and
safely disinfects the environment using light-emitting diodes (LEDs) by emitting a high-intensity, narrow-spectrum (HINS) light, has been proposed as an infection prevention strategy.5–7 This technology uses LEDs to create a narrow bandwidth of high- intensity visible violet light with a peak output of 405 nm. The
Author for correspondence: William A. Rutala, PhD, UNC School of Medicine,
Division of Infectious Diseases, UNC School of Medicine, Bioinformatics Building, CB#7030, Chapel Hill, NC 27514-7030. E-mail:
brutala@med.unc.edu
Cite this article: Rutala WA. et al. (2018). Antimicrobial activity of a continuous
visible light disinfection system. Infection Control & Hospital Epidemiology 2018, 39, 1250–1253. doi: 10.1017/ice.2018.200
© 2018 by The Society for Healthcare Epidemiology of America. All rights reserved.
wavelength of the LEDs is certified by the manufacturer to be 405nm ± 3 nm. This light in turn reacts with porphyrin mole- cules to generate reactive oxygen species that kill microorgan- isms.5 The purpose of this evaluation was to determine the effectiveness of HINS light for the reduction of epidemiologically important pathogens in the environment.
Methods Light source and irradiance
An overhead, visible light disinfection technology (Indigo-Clean, Kenall Manufacturing, Kenosha, WI) was evaluated in 2 different clinical configurations. In phase 1 (“white” lights), two61-cm × 61- cm(2-foot × 2-foot) blended-white, ceiling-mounted fixtures were used to provide both disinfection and ambient white illumination for use in normal clinical conditions in an occupied room. The measured surface irradiance of this “white” disinfecting light at the pathogen location was ~0.12–0.16 mW/cm2. In phase 2 (“blue” light), a higher-level of disinfection light was studied by adding a 61- cm× 122-cm(2-foot × 4-foot) overhead “blue” light fixture to the 2 preexisting 61-cm × 61-cm overhead, blended-white fixtures. The measured surface irradiance of disinfecting “blue” light at the pathogen locationwas ~0.34–0.44mW/
cm2.Thesurface irradiance measurements in the control area yielded values of 0.00 mW/cm2 (no measurable disinfecting light). These surface irradiance mea- surements were made using a National Institute of Standards and Technology (NIST)-calibrated spectroradiometer (model no. USB2000+, Ocean Optics, Wesley Chapel, FL). Phase 1 and phase 2 testing were conducted in a 12.5m2 (134
ft2) room. The room used did not have windows or external sources of light. Each of the 3 lights described above were con- nected via separate light switches and were simply switched “on” and “off” at the wall switch. Light placement was designed to treat
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