January 23, 2017
3 min read

UV-C light kills drug-resistant bacteria in hospital rooms

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Adding ultraviolet C light to standard terminal cleaning strategies significantly decreased transmission of selected bacteria in patients who stayed overnight in a room where an infected patient was previously treated, according to researchers.

Deverick J. Anderson, MD, MPH, associate professor of medicine at the Duke University School of Medicine, and colleagues examined the effect of three enhanced disinfection strategies on the transmission of MRSA, vancomycin-resistant enterococci, Clostridium difficile and multidrug-resistant Acinetobacter.

Deverick J. Anderson, MD, MPH
Deverick J. Anderson

They compared the results with standard terminal cleaning procedures in the hospital rooms of former patients who were on contact precautions.

"Our study is the first multicenter randomized trial to demonstrate that bad pathogens can spread from the environment," Anderson told Infectious Disease News. "While there has been increasing reports to suggest this is the case, there remained some skepticism."

A 30% overall reduction

Anderson and colleagues conducted a pragmatic, cluster-randomized, crossover trial from April 2012 to July 2014 in nine hospitals — eight in North Carolina and one in Virginia. The locations included six community and two tertiary hospitals, and one Veterans Affairs medical center. They used four strategies to disinfect the rooms of patients who were discharged or transferred, including the standard procedure of employing quaternary ammonium-containing disinfectant in all rooms except those in which the patient had C. difficile. In those cases, bleach was used. In the second group, they added UV-C disinfection (Tru-D Smart UVC) to standard procedures. The third procedure used UV-C light and bleach, and the fourth included just bleach.

Credit: Shawn Rocco/Duke Health.
A UV-C device used in the study.
Source: Shawn Rocco/Duke Health.

In all, 21,395 exposed patients met the criteria for inclusion in the study: 4,916 in the reference group, 5,178 in the quaternary ammonium or bleach plus UV-C group, 5,863 in the bleach plus UV-C group, and 5,438 in the bleach-only group.

The enhanced disinfection strategies led to a 10% to 30% overall reduced likelihood of patients acquiring the same infection as a previous patient. The most effective strategy was adding UV-C light to standard disinfection procedures, which decreased in the incidence of target organisms by 30% overall, leading to lower rates of infection in eight of the nine hospitals.

However, Anderson and colleagues noted no statistically significant decrease in infections after using bleach or bleach plus UV-C. They also noted that the incidence of C. difficile was not different after adding UV-C light to standard bleach disinfection.

According to a news release about the study, the portable UV-C devices — which kill bacteria by disrupting their DNA —were turned on for about 30 minutes in the rooms.

"I think it will be hard to argue that the environment is not an important issue after our study," Anderson said. "The good news is that our study also demonstrates that the risk from the environment can be decreased, and the way to achieve the decrease is through enhanced disinfection."

‘Surprised’ by C. difficile results

Previous studies, including one by University of Pennsylvania researchers, have shown that UV devices decrease C. difficile infection by 22% to 53%, Anderson and colleagues noted — a clinical effectiveness not replicated by their study.

“In light of these results,” they wrote, “we were surprised by the lack of change in rates of C. difficile among exposed patients.”

They said several factors might explain the difference, including an approximately 90% compliance with the use of bleach in the study, which may have left few spores for the UV device to eliminate. Other possible factors include where the UV-C device was placed and the possibility that the environment might not play as big a role in C. difficile transmission as previously suspected, Anderson and colleagues said.

“Our post-hoc analysis excluding patients exposed to C. difficile showed that the effect in the UV group was strengthened and the effect in the bleach and UV group became statistically significant,” they wrote. – by Gerard Gallagher

Disclosure: Two researchers reported receiving consulting fees from Clorox.