Efficacy of ultraviolet C radiations against bacteria, fungi and coronavirus

Miss Mahjabeen Khan¹, Murray McDonald², Kaustabh Mundada², Andres Ruiz², Professor Mark Willcox¹

¹Unsw Sydney, Sydney, Australia, ²Mobile UV innovations, Melbourne, Australia

Introduction

Ultra-violet (UV) C (200-280 wavelength) has long been known for its antimicrobial and disinfecting efficacy. It damages DNA by causing dimerization of pyrimidines. A newly designed technology (Mobile UV Innovations, Melbourne, VIC) that emits UVC at 240 nm is composed of an enclosed booth with three UVC light stands each with four bulbs has been developed for disinfecting hospital equipment. The aim of this project was to examine the spectrum of activity of this device.

Methods

Experiments were designed following ISO_21702-2019-1, EN14561, BSEN14476-2005, BSEN14562-2006 and AOAC-Official-Method-966.04 standards for surface disinfection after drying microbes on glass slides. Disinfection activity was analysed for strains of Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 6294), Candia auris (ATCC 12373), spores of Aspergillus niger (ATCC 16404), murine hepatitis virus (ATCC VR-261; surrogate coronavirus), as well as methicillin resistant Staphylococcus aureus, carbapenemase resistant Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhi.

Results

The parameters of time, number of lights and direction of sample facing the lights were examined. MUVI-UVC was able to kill 99.99% of all the tested bacteria, fungi and coronavirus if used for 5 minutes using all three lights in the setup with the glass slide in a vertical position. However, for fungal spores, 20 minutes were required to achieve 99.99% killing. There was a small but insignificant effect of having the surface horizontally or vertically aligned to the UV lights.

Conclusion

MUVi-UVC device is effective technology to disinfect devices. Future research will examine different surfaces to see  if the surface material affects disinfection.

Biography:

I am a Microbiologist and completed my PhD in 2021 from UNSW Sydney in Microbiology and molecular biology. During my PhD I explored the eye infections caused by the bacterium Pseudomonas aeruginosa and found novel and interesting facts about the resistance virulence and clinical relation of this bacteria. After PhD completion I worked for Mobile UV Innovations Melbourne in which I tested the efficacy of their designed UVC technology for disinfections against different microorganisms. Currently, I am working with Professor Mark Willcox at UNSW as a researcher for an Industry project.