Pulsed-Xenon Ultraviolet Light System Demonstrates Powerful Activity Against Candida auris

A 10-minute cycle of pulsed-xenon ultraviolet (PX-UV) light on glass slides inoculated with Candida auris reduced the number of colony forming units per milliliter by 99.6%, a new study published in BMC Infectious Diseases demonstrates.

C auris is a growing public health concern because of its hardiness, especially in health care settings, and its antibiotic-resistance profile. Earlier this year, The New York Times lead a front-page story with this troubling tale:

“The man at Mount Sinai died after 90 days in the hospital, but C auris did not. Tests showed it was everywhere in his room, so invasive that the hospital needed special cleaning equipment and had to rip out some of the ceiling and floor tiles to eradicate it.”

Indeed, C auris is an emerging fungus that has health care providers on high alert.

“Unique characteristics of C auris make it a serious and challenging global health threat and it continues to be poorly recognized cause of infection among health care providers,” Bhagyashri D. Navalkele, MD, medical director of Infection Prevention at the University of Mississippi Medical Center, who has written about the bug, told Contagion^® earlier this year. “C auris is a tricky fungus as it mimics other less harmful Candida species, causing a delay in identification and management. It can affect any age group, and is known to be very difficult to treat due to multidrug resistance; [thus], it is associated with high mortality and transmission risk resulting in outbreaks.”

Investigators in South Africa are exploring ways to stop and destroy C auris in its tracks with the help of a PX-UV robot system (Xenex LightStrike), which also recorded activity against C parapsilosis, another emerging fungus that is problematic, especially in health care settings.

The research team inoculated glass slides with 10 μl of stock culture carried out in a broth liquid medium at 37°C until concentration ranges 10 ⁵—10 ⁶ colony-forming units (CFUs) per milliliter were obtained. The slides were then allowed to dry and placed perpendicularly to the floor at 1.25 meters. The slides were exposed uninterrupted to PX-UV light for 5-, 10-, and 15-minute cycles at 1- and 2-meter distances.

After a 5-minute cycle at 1-meter distance, there was a 99.4% reduction in C auris CFU, which jumped to a 99.6% reduction after 10 minutes at 2 meters. Similarly, there was a 98.5% reduction in C parapsilosis CFU after a 5-minute cycle at 1-meter distance, and a 95.2% reduction after 10 minutes at 2 meters.

“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,” investigators concluded. “Further studies are needed in hospital environment, to assess the cumulative impact of repeated sessions.”