Ultraviolet Light Helps Battle Superbugs

By Jane Farrell

Ultraviolet light could help in keeping drug-resistant bacteria from lingering in patients’ rooms and causing new infections, researchers say

The new tool is known as UVC.

Some hospitals have already begun using UVC machines in addition to standard chemical disinfection to kill potentially dangerous bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), but research on their effectiveness has been preliminary.

A large randomized trial led by Duke Health and published in The Lancet finds use of UVC machines can cut transmission of four major superbugs by a cumulative 30 percent. The finding is specific to patients who stay overnight in a room where someone with a known positive culture or infection of a drug-resistant organism had previously been treated.

“Some of these germs can live on the environment so long that even after a patient with the organism has left the room and it has been cleaned, the next patient in the room could potentially be exposed,” said Deverick J. Anderson, M.D., an infectious disease specialist at Duke Health and lead investigator of the trial, which included more than 21,000 patients. “Infections from one of these bugs are tough and expensive to treat and can be truly debilitating for a patient. For hospitals, these infections also cause a burden of costs that often aren’t reimbursable.”

The researchers focused on four drug-resistant organisms: MRSA, vancomycin-resistant enterococci (VRE), C. difficile and Acinetobacter.

The trial was conducted from 2012 to 2014 at nine hospitals in the Southeast, including three Duke University Health System hospitals, a Veterans Affairs hospital, and small community health care settings.

The facilities used a portable machine called the Tru-D SmartUVC to disinfect rooms where patients with the target bacteria had been staying. For about 30 minutes, the machine emits UVC light into an empty room, the light bouncing and reflecting into hard-to-reach areas such as open drawers or between cabinets and fixtures. The light waves kill bacteria by disrupting their DNA.

The trial compared standard disinfection with quaternary ammonium to three other cleaning methods: using quaternary ammonium followed by UV light; using chlorine bleach instead of quaternary ammonium and no UV light; and cleaning with bleach and UV light.

Overall, the most effective strategy was using quaternary ammonium followed by UV light. This combination led to the 30 percent decrease in overall transmission and was particularly effective against transmission of MRSA, resulting in a 22 percent reduction in transmission.

The researchers found that using chlorine bleach instead of quaternary ammonium cut transmissions of VRE by more than half (57 percent). Adding UV light to the bleach regimen was even more successful, cutting VRE transmission by 64 percent.

None of the cleaning methods significantly reduced the incidence of C. difficile, an infection that takes hold in the gut. The incidence of Acinetobacter was limited to one case, so researchers did not include it in their analyses.

UVC machines are now being manufactured by several companies and are priced upwards of $90,000. Results of this study suggest that use of this technology would allow hospitals to better care for their patients by reducing their risks of acquiring these infections, while at the same time reducing their overall costs, the study authors said.

But hospitals must also consider that UVC disinfection adds at least 30 minutes to the cleaning process, which could impact waiting times for patients. Despite this limitation, hospitals in the trial were able to achieve 90 percent compliance with the UV machine using careful planning and communication, but a formal cost-effectiveness analysis has yet to be completed, Anderson said.

The Duke researchers are planning to look at other day-to-day strategies hospitals can use to manage infections, such as non-ultraviolet lights that are safe to use near people but also can halt the proliferation of germs.