Ultraviolet Light Kills Bacteria

Researchers at Duke University Medical Center and the University of North Carolina Hospital System used short-wave ultraviolet radiation (UV-C) to nearly eliminate Acinetobacter, Clostridium difficile or vancomycin-resistant enterococci (VRE) in more than 50 patient rooms at the two medical facilities.

"We are learning more and more about how much the hospital environment contributes to the spread of these organisms," said lead researcher Doctor Deverick J. Anderson, MD, an assistant professor of medicine at Duke. Given previous findings by the University of North Carolina team that UV-C is effective at decreasing methicillin-resistant Staphylococcus aureus (MRSA) in hospital rooms, he believes that the new study lays critical groundwork. "We have a solid foundation to show that this approach succeeds in both experimental and real-world conditions," Anderson said. "Now it's time to see if we can demonstrate that it indeed decreases the rate of infections among patients."

UV-C, which is harmful to microorganisms, has been used for decades in food, air and water purification and to sterilize equipment in laboratory settings. In their study, the Duke and University of North Carolina researchers questioned whether UV-C could be utilized to eliminate three of the most problematic germs and improve the cleanliness of patient rooms. The study demonstrates that its medical application may offer new strategies for reducing hospital-associated infections. The study focused on general-medical and intensive-care units of the two medical centers and identified patients with infections from the targeted bacteria. Each bacterium can survive for prolonged periods on surfaces.

After the patients were discharged, the researchers obtained multiple cultures from each of five specific locations in the hospital rooms and bathrooms – "high-touch" areas that included bed rails, remote controls and toilets. A special machine with eight UV bulbs mounted on a central column was then positioned strategically in each room and turned on for as long as 45 minutes to eradicate both vegetative bacteria and bacterial spores. Fifteen more cultures were taken from the same locations in every room, and the pre- and post-treatment bacteria counts were compared.

The numbers of bacterial CFUs, or colony-forming units, fell precipitously. Fifty-two CFUs of Acinetobacter were seen before irradiation, but only 1 CFU afterward – down 98.1 percent. As for VRE, the proportion decrease was nearly the same – 719 CFUs before and 15 after, a 97.9 percent drop. The culturing initially was not sensitive enough to isolate C. diff, but improved techniques allowed the researchers to do further testing and the results in the UV-C treated rooms were just as dramatic.

"We would never propose that UV light be the only form of room cleaning, but in an era of increasing antibiotic resistance, it could become an important addition to hospitals' arsenal," Anderson said.

COMPAMED.de; Source: Society for Healthcare Epidemiology of America