The efficacy of pulsed-xenon ultraviolet light technology on Candida auris

Candida auris is an emerging, often multi-resistant, yeast that causes invasive infections in healthcare settings. Patients may be colonized for months and C. auris has been shown to remain viable on surfaces for at least 14 days. It is widely considered that the environment may be a reservoir for transmission of C. auris. The efficacy of pulsed-xenon ultraviolet (PX-UV) mobile devices on C. auris has not been tested previously. In a laboratory setting, we tested efficacy of a PX-UV system on C. auris and C. parapsilosis, another candida known to be responsible for outbreaks in healthcare settings and survive for at least 28 days in the environment.

Cultures and growth of clinical strains of C. parapsilosis and C. auris was carried out in a broth liquid culture medium at 37 °C until concentration ranges 10 ⁵-10 ⁶ colony-forming units (CFUs) per millilitre were obtained. Glass slides were inoculated with 10 μl of C. auris stock culture and allowed to dry. Slides were positioned perpendicular to the floor at a distance of 1.25 m from the floor. Exposure time were run uninterrupted for 5-, 10- and 15-min cycles at 1- and 2-m distance.

There was a 99.4% reduction in C. auris CFU after a 5-min cycle at 1-m distance, and 99.6% reduction after a 10-min cycle at 2-m distance. There was a 98.5% reduction in C. parapsilosis CFU after a 5-min cycle at 1-m distance, and 95.2% reduction after a 10-min cycle at 2-m distance.

The PX-UV mobile device is easy to use and has short cycle times that makes it easier to disinfect all areas outside the room where the patient received care. Further studies are needed in hospital environment, to assess the cumulative impact of repeated sessions.