The effect of Indigo-Light Continuous Environmental Disinfection System on Microbial Contamination and SSI in an Orthopedic OR

Published: 25 October 2018| Version 1 | DOI: 10.17632/3btb7r7yrj.1
Erin Hamilton


A growing body of research has demonstrated that manual cleaning and disinfection of the operating room (OR) is suboptimal. Residual environmental contamination may pose an infection risk to the surgical wound. This study evaluates the impact of visible light continuous environmental disinfection system (Indigo-light CED) on microbial surface contamination and surgical site infections (SSI) in an OR. It was performed between Oct 2015 and Oct 2017 at Maury Regional Health Center, a 255-bed regional hospital in Columbia, TN. The hospital has 12 ORs, with 3 dedicated to orthopedic surgery being the ORs of interest in this study. The most common procedures performed in all three ORs are primary joint arthroplasties (total knee>total hip>shoulder>ankle). The use of the Indigo-light CED was designed to be an additional disinfection strategy complementary to the hospital’s standard OR cleaning and disinfection protocol and preexisting SSI bundle. The Indigo-light CED system (Indigo-Clean, Kenall, Kenosha, WI) was installed by the institution in one OR (OR2) on Oct 15, 2016. OR2 is adjacent to another OR (OR1) with which it shares a heating, ventilation, and air conditioning system (HVAC). A third OR (OR3), included in the data analysis for SSIs, was across the hall from ORs1 and 2 and had a separate HVAC system. All three ORs are humidity-controlled and maintained between 66- and 68-degrees Fahrenheit. It is important to note that the deployment and usage of Visible Light CED is very different from portable, UV systems. As it is integrated into the overhead lighting it requires additional considerations related to the center wavelength (per photon efficacy), irradiance (disinfecting power at a point in space) and number of fixtures/layout (disinfecting power throughout the room) to ensure the proper end result. This implies that no two products in this category will be identical, thus the importance of clinical evidence in evaluating their true benefits based upon the manufacturer’s recommended usage. Samples from surfaces within the two contiguous ORs sharing an air supply (OR1 and OR2) were obtained after manual cleaning on multiple days before (Period1) and multiple days after (Period2) Indigo-light CED installation in OR2 only. Samples were incubated and enumerated as total colony-forming units (CFU). SSIs in both OR1 and OR2 and a distant OR (OR3) were tracked for one year prior to and one year after Indigo-light CED installation. There was an 81 (p-value=0.017) and 49 % (p-value=0.015) reduction in total CFUs after Indigo-light CED installation in the OR in which the system was installed and the contiguous OR, respectively. In the OR with the Indigo-light CED, SSIs decreased from 1.4% in the year prior to installation to 0.4% following installation (p-value=0.029). Indigo-light CED, used in conjunction with manual cleaning, resulted in significant reductions in both microbial surface contamination and SSIs in the OR.


Steps to reproduce

The effect of the Indigo-light CED on bacterial levels on surfaces throughout OR1 and OR2 was studied before and after installation of the light system in OR2. For a baseline, surface samples were collected on 5 occasions between Oct 4 and Oct 14, 2016 (Period 1) in both ORs prior to the installation of the Indigo-light in OR2 on Oct 15. The same surfaces in both ORs were then sampled on eight different occasions between Oct 19 and Nov 4, 2016 (Period 2). The 50 surfaces sampled were the same in both ORs and in both periods and included the tops and bottoms of the door handle on the inside of the main door to the OR, door handle to the blanket storage cabinet, comp mouse, keyboard, inside of phone handle, door handle to glove storage cabinet, boom light control, right arm of the anesth chair, left arm of the anesth chair, left edge of the anesth cart, and right edge of the anesth cart. Surfaces were also sampled above and below the top of the IV warmer, lower left front corner of the anesth machine, lower right front corner of the anesth machine, handle of the fluid collection machine and on the left and right sides of the laundry bin lid, top of the OR chair, computer keyboard, top of computer, front of the anesth screen, top of the syringe bin, front of the bovie machine, top of the fluid collection machine, anesth monitor, and blood pressure button. All samples were collected in both ORs and periods between 5-6am, prior to the first room entry and after the room had been terminally cleaned the previous evening. Samples were collected using 15x65mm Baird Parker with egg yolk tellurite contact plates. Non-flat surfaces were sampled using the roll plate technique and flat surfaces were sampled by directly pressing plates against the surface. Each sample was taken directly to the lab for a 48-hr incubation period at 35 degrees C. Following incubation, enumeration of total colony forming units (cfu) from each plate was made by a blinded microbiology tech and results tallied to create a total cfu count for each OR on the date of collection. Two more variables were collected in the bacterial analysis. These were the number of surgical cases performed since the prior data collection, and the total duration in minutes of all surgical cases performed since the prior data collection. SSI rates following procedures performed in the OR was the second outcome of interest. This data was collected in three ORs. OR1 and OR2 are the same ORs referred to in the bacterial analysis. A 3rd distant OR (OR3) was added for comparison of data between ORs 1 and 2 and an OR that was not neighboring or sharing an air supply system (control). SSI case data from each OR were collected between Oct 2015 and Oct 2017 for one year’s worth of data (period 1) prior to the installation of the Indigo-light CED in OR2 on Oct 15, 2016 and one year’s worth worth after installation (period 2). All statistical analysis was performed using R statistical software (v3.4.4).


Maury Regional Medical Center


Surgical Infection, Disinfection, High Intensity Lighting, Contamination, Operating Room