Use of Pulse Xenon Ultraviolet to Deactivate Clostridium difficile, Methicillin Resistant Staphylococcus Aureus and Vancomycin Resistant Enterocci

Background: Clostridium difficile (C. diff.), Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-resistant Enterocci (VRE) are three of the most common organisms potentially spread via fomites in the clinical environment. These organisms result in hundreds of thousands of serious infections each year. Pulsing a xenon flashlamp produces ultraviolet (UV) light in the germicidal (UV-C) spectrum. This light is able to penetrate cells walls and damage the DNA of microorganisms (causing the formation of thymine dimers and other damage), which deactivates microorganisms (by rendering them non-infectious because they are unable to reproduce). The potential of high-intensity, broad spectrum UV light to disinfect clinical care areas of C. diff., MRSA and VRE is explored.

Objective: To determine the efficacy of a pulse xenon ultraviolet lamp for the disinfection of surfaces contaminated by C. diff., MRSA and VRE in the laboratory.

Methods: The test organisms (C. difficile ATCC 43598 endospores) were heat-shocked after soil addition but prior to deposition on the test coupons (glass). Following ultraviolet exposure (and separately for “time zero” controls), the endospores were cultured on blood agar “Oxyplates” with supplements. Clostridium difficile was deposited on test coupons at three separate time points (t=zero (control), t=8 minute and t=12 minutes) at a distance of 1 meter from the flashlamp, resulting in a total of nine samples. 4 samples of MRSA and 4 samples of VRE were placed on glass slides after the addition of soil, placed at a distance of 2 meters from the UV flashlamp and exposed to a UV dose of 480 seconds. The experiment was conducted at an independent microbial testing laboratory.

Results: Colony forming units (CFUs) of C. diff. averaged 3.33E+05 for the samples not exposed to the UV flashlamp (control). After an 8-minute exposure to pulse xenon ultraviolet, the average CFUs of C. diff. were 4.33E+01. After a 12-minute exposure to the pulse xenon ultraviolet, the average CFUs of C. diff. were 6.67E+00. The control samples for MRSA averaged 1.23E+05. After 480 seconds of xenon UV exposure at 2 meters, less than 10 CFUs were present. The control samples of VRE averaged 2.75E+04. After 480 seconds of xenon UV exposure, less than 10 CFUs were present.

Conclusions: Pulse xenon ultraviolet light is an effective and efficient means of disinfecting surfaces contaminated with Clostridium difficile, MRSA and/or VRE, providing an alternative means to bleach and other chemical disinfectants for use in clinical settings.