Ultraviolet light can enhance hospitals’ efforts to disinfect patient rooms from drug-resistant bacteria, according to a new study led by Duke Health.

The study, recently published in The Lancet, tested the use of a type of ultraviolet light called UVC against four superbugs: methicillin-resistant Staphylococcus aureus, or MRSA; vancomycin-resistant enterococci, or VRE; Acinetobacter and Clostridium difficile. The trial compared standard disinfection using quaternary ammonium with three other cleaning methods: quaternary ammonium followed by UV light, chlorine bleach without UV light, and bleach with UV light. The study was conducted in nine Southeast hospitals and included more than 21,000 patients, each of whom stayed overnight in a room where someone with a known positive culture or infection of a superbug had been treated.

The UV light machine was set up in a relatively central location in the room being readied for the next patient so that the light could bounce into open drawers, the bathroom and hard-to-reach areas, according to Deverick Anderson, M.D., an infectious diseases specialist at Duke Health and lead researcher.

The researchers found that the additional cleaning provided by the UV light cumulatively decreased infection by 30 percent in the patient who occupied the room next. The results for each bug varied. For instance, using UV light and standard cleaning decreased MRSA 22 percent and VRE 60 percent. Using bleach decreased VRE 57 percent; when UV light treatment was added, the decrease was 64 percent, says Anderson.

“Most of the impact of UV was on MRSA and VRE,” he says.

The UV light did not work as well on C. difficile, which is where the researchers thought they’d see the biggest impact. Anderson attributes that result in large part to the fact that the use of bleach before adding UV light had been very successful, so that there wasn’t much C. difficile left for the UV light to work on.

Anderson also suggested two key takeaways from the study. “This is the first trial that truly demonstrates that the environment is a risk to patients. This is not a debate anymore. The good news is that we can decrease that risk, and the best way is by using an enhanced strategy for cleaning,” he says.

He adds that “just preventing a handful of cases will make it cost effective. These kinds of strategies are worth investing in.”