Narrow wavelength of UV light safely kills drug-resistant bacteria
NEW YORK (June 8, 2016) – Scientists from the Center for Radiological Research at Columbia University Medical Center have shown that a narrow wavelength of ultraviolet (UV) light safely killed drug-resistant MRSA bacteria in mice, demonstrating a potentially safe and cost-effective way to reduce surgical site infections, a major public health concern.
A paper just published by PLOS ONE describes how the Columbia team found that a particular wavelength of UV light known as "far-UVC" (in this instance, 207 nanometers) is not only as effective as conventional germicidal UV light in killing MRSA, as shown in their previously published study, but also shows for the first time that, unlike conventional germicidal UV, far-UVC does not cause biological damage to exposed skin.
"Our new findings show that far-UVC light has enormous potential for combating the deadly and costly scourge of drug-resistant surgical site infections," said David J. Brenner, PhD, Higgins Professor of Radiation Biophysics, director of the Center for Radiological Research, and the senior author of the paper.
"We've known for a long time that UV light has the potential to reduce surgical site infections, because UV can efficiently kill all bacteria, including drug-resistant bacteria and even so-called 'superbugs.' Unfortunately, it's not possible to use conventional germicidal UV light when people are around because it's a health hazard to patients and medical personnel. What we showed in our earlier work is that far-UVC light is as effective at killing MRSA as conventional germicidal UV light — and now with this new research, we have demonstrated that far-UVC kills bacteria but without risk of skin damage," Dr. Brenner said.
Surgical site infections (SSI) continue to be a critical health care issue in the US and worldwide. Patients who develop SSI have a mortality rate twice that of non-infected patients, and estimated annual healthcare costs in the U.S. due to SSI range from $3 to $10 billion.
The new idea behind Columbia's use of far-UVC light is that that, unlike conventional germicidal UV, far-UVC cannot penetrate through the outer, dead layer of skin to reach live skin cells, nor can it penetrate the outer layer of the eye. However, because bacteria and viruses are physically very small, far-UVC light can penetrate and kill them. Columbia's latest research was conducted on the skin hairless mice, which responds similarly to human skin when exposed to UV light.
"Our findings offer a potential practical pathway towards significantly reducing surgical site infection rates without risk to the health and safety of patients and medical personnel," added Dr. Brenner. "One of our next steps is to explore direct studies in surgical settings, in larger animals and humans. From there we can investigate other new applications of these exciting findings, like killing airborne bacteria and viruses such as TB and influenza."
"207-nm UV Light — A Promising Tool for Safe Low-Cost Reduction of Surgical Site Infections. II: In-Vivo Safety Studies" was published online on June 8, 2016 in PLOS ONE. Authors are David J. Brenner, Manuela Buonanno, Brian Ponnaiya, Alan W. Bigelow, Gerhard Randers-Pehrson, Yanping Xu, Igor Shuryak, and Lubomir Smilenov, at the Center for Radiological Research, Columbia University Medical Center; Milda Stanislauskas at the Department of Dermatology, Columbia University Medical Center; and David M. Owens at the Departments of Dermatology and Pathology and Cell Biology, Columbia University Medical Center.
The Shostack Foundation and USHIO Inc. of Tokyo, Japan provided funding for this research. USHIO has license and research agreements with Columbia University.
The authors declare no other conflicts of interest.
The Columbia University Center for Radiological Research has been studying the biological effects of both low and high doses of radiation for exactly 100 years, since its founding in 1916 by a student of Marie Curie. Their main research themes are 1) to provide better radiotherapy treatments for cancer, 2) to better understand the risks associated with exposure to very low doses of radiation, 3) to improve the nation's ability to respond to a large-scale radiological event, 4) understanding radiation health risks during space missions, as well as 5) to develop new ultraviolet light techniques to safely kill common bacteria and viruses. For more information visit crr.columbia.edu.
Columbia University Medical Center provides international leadership in basic, pre-clinical, and clinical research; medical and health sciences education; and patient care. The medical center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the College of Physicians and Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. For more information, visit cumc.columbia.edu.