A study by Columbia University Medical Center (CUMC), New York, NY, researchers suggests that narrow-spectrum ultraviolet (UV) light could dramatically reduce surgical infections without damaging human tissue.
Between 200,000 and 300,000 patients suffer surgical wound infections in the US each year, accounting for $3 billion to $10 billion in health-care expenditures, the researchers report. Patients with these infections are 60 percent more likely to spend time in an ICU, are five times as likely to be readmitted to the hospital, have twice the mortality rate, have longer hospital stays, and have roughly double the total health-care costs of patients without surgical wound infections.
Scientists have known for many years that UV light from a standard germicidal lamp (which emits a broad spectrum of wavelengths, from about 200 to 400 nanometers [nm]) is highly effective at killing bacteria; such lamps are routinely used to decontaminate surgical equipment.
Unfortunately, this UV light is also harmful to human tissue and can lead to skin cancer and cataracts in the eye. Therefore, UV light is almost never used in the operating room during surgery.
However, the scientists hypothesized that a very narrow spectrum of UV light—around 207 nm—might be capable of destroying bacteria while leaving human tissue unaffected. Because UV light at this wavelength is strongly absorbed by proteins, it is expected to be safe for two reasons: At the cellular level, it cannot reach the nucleus of human cells, and at the tissue level it cannot reach the sensitive cells in the skin epidermis and the eye lens. But because bacteria are much smaller than human cells, this UV light can reach their DNA.
To test their hypothesis, they exposed MRSA (methicillin-resistant S. aureus) bacteria, a common cause of surgical wound infections, and human skin cells to a krypton-bromine excimer lamp, which emits UV light only at 207 nm, as well as to a standard germicidal UV lamp.
They found that 207-nm UV light was as effective at killing MRSA bacteria as a conventional UV lamp. However, the 207-nm light resulted in 1,000-fold less killing of human skin cells than did the standard UV light.