Inactivation of the multi-drug-resistant pathogen Candida auris using ultraviolet germicidal irradiation

• Published in: The Journal of hospital infection Vol. 105; no. 3; pp. 495 - 501
• Main Authors: Lemons, A.R., McClelland, T.L., Martin, S.B., Lindsley, W.G., Green, B.J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2020
• Subjects: Candida auris; Disinfection; Drug resistance; Emerging pathogen; Ultraviolet germicidal irradiation; Ultraviolet inactivation; Candida auris; Disinfection; Emerging pathogen; Ultraviolet germicidal irradiation; Drug resistance; Ultraviolet inactivation; drug-resistance; UV inactivation; ultraviolet germicidal irradiation; disinfection; emerging pathogen
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2020.04.011

Candida auris, a multi-drug-resistant fungal pathogen, has become an emerging threat in healthcare settings around the world. Reliable disinfection protocols specifically designed to inactivate C. auris are essential, as many chemical disinfectants commonly used in healthcare settings have been shown to have variable efficacy at inactivating C. auris. Ultraviolet germicidal irradiation (UVGI) was investigated as a method to inactivate clinically relevant strains of C. auris. Ten C. auris and two C. albicans isolates were exposed to ultraviolet (UV) energy to determine the UV dose required to inactivate each isolate. Using a UV reactor, each isolate (106 cells/mL) was exposed to 11 UV doses ranging from 10 to 150 mJ/cm2 and then cultured to assess cell viability. An exponential decay model was applied to each dose–response curve to determine inactivation rate constants for each isolate, which ranged from 0.108 to 0.176 cm2/mJ for C. auris and from 0.239 to 0.292 cm2/mJ for C. albicans. As the model of exponential decay did not accurately estimate the dose beyond 99.9% inactivation, a logistic regression model was applied to better estimate the doses required for 99.999% inactivation. Using this model, significantly greater UV energy was required to inactivate C. auris (103–192 mJ/cm2) compared with C. albicans (78–80 mJ/cm2). UVGI is a feasible approach for inactivating C. auris, although variable susceptibility among isolates must be taken into account. This dose–response data is critical for recommending UVGI dosing strategies to be tested in healthcare settings.