Low-intensity UV-C radiation removes some pathogens from keyboards

Last Updated: 2016-02-05

By Shannon Aymes

NEW YORK (Reuters Health) - Automated low-intensity ultraviolet-C radiation of hospital keyboards reduces bacterial counts, though less so for Clostridium difficile.

"Keyboards in healthcare settings are used by a wide variety of staff and rarely are hands washed because the keyboard has been used," said Dr. Peter Wilson, a microbiologist at University College London Hospitals in the U.K., who was not involved in the new work.

"Therefore organisms picked up from the environment are transmitted to the keyboard and then to other users," Dr. Wilson told Reuters Health by email. "UV-C can remove many of these organisms and reduce the chance of spread of infection in the ward. We use a keyboard with an inbuilt alarm and software displaying a notice on the screen to make users clean the keyboard every 12 hours as we were concerned about misuse of the UV sources and health and safety."

In the new study, Dr. Curtis Donskey of Case Western Reserve University School of Medicine in Cleveland, Ohio, and colleagues positioned a UV-C device four inches directly above the keyboard and programmed it for an automated six-minute decontamination cycle between uses.

The efficacy of the UV-C device was tested against strains of meticillin-resistant Staphylococcus aureus (MRSA), C. difficile, and carbapenem-resistant Escherichia coli on steel carriers. The keyboards were cultured before and after one cycle of decontamination.

Exposure of MRSA and E. coli directly under the UV-C device reduced recovery of the bacteria by more than three logs with one six-minute cycle, the team reports in in the American Journal of Infection Control, online January 15.

Placing the steel carrier three keys lateral to the UV-C lamp led to similar reductions of MRSA, whereas placing it nine keys lateral to the lamp produced less reduction in cycles 1 and 2.

In order to reach more than a one-log reduction in C. difficile, four six-minute cycles were required.

There was no evidence of detectable UV-C within six or 12 inches of the keyboard.

Exposure of 20 contaminated keyboards to low-intensity UV-C radiation reduced the number of keyboards positive for any potential pathogen to five (p=0.0001), the researchers found.

"UV-C is an effective method to cut contamination of keyboards and potentially reduce infection spreading in hospital wards," Dr. Wilson said. "However safety is a concern and C. difficile can survive unless removed by a physical wipe. Shadowing negates the efficacy of UV light in some areas. A smooth flat keyboard is best suited to prevent organisms accumulating."

Dr. Danielle Zerr, professor of pediatric infectious diseases at Seattle Children's Hospital in Washington, who was not involved in the study, told Reuters Health by email, "It is important to find effective and efficient ways to decontaminate the hospital environment, especially frequently touched surfaces. Keyboards can become contaminated. Hand hygiene after touching the environment remains an important practice."

The study was supported by a grant from the U.S. Department of Veterans Affairs. Dr. Donskey reported serving on the advisory board for Clorox and research grants from GOJO, Clorox, STERIS, and EcoLab. He did not respond to a request for comment by press time.

SOURCE: bit.ly/1NTYJQh

Am J Infect Control 2016.