UV Light the Key to Locking down MRSA Infections?

mrsa

Even though doctors and nurses take great pains to make sure that operating rooms are germ-free environments,  surgical wound infections, especially those involving methicillin-resistant Staphylococcus aureus (MRSA), still remain a serious problem.  Every year, about 200,000 to 300,000 Americans will suffer from a surgery-related infection.  And, about 8,200 of these patients will die.  However, researchers at Columbia University Medical Center (CUMC) think they may have found a solution:  narrow-spectrum UV light.

Scientists have actually known for quite some time that UV light does a good job in killing bacteria.  In fact, germicidal lamps are often used to disinfect surgical equipment.  Unfortunately, the broad spectrum of wavelengths that these devices emit – 200 to 400 nm – is not safe to use on human tissues.

One example of the type of harm that UV light can do which is very familiar to most people is skin cancer caused by harmful UV radiation from the sun.  UV light is also associated with the formation of cataracts, a condition in which the lens of the eye become cloudy.

According to study author David J. Brenner, these health risks would normally make it very difficult to use UV light in an operating room, because both patients and medical personnel would have to use cumbersome protective equipment.

However, Brenner and his team had a different idea:  what if they used only a narrow spectrum of UV light in the range around 207 nm?  If this wavelength could kill bacteria without destroying delicate human tissues, then it could be used in the operating room to kill any stray bacteria, such as MRSA, which might ordinarily cause infections during surgery.

In order to test their theory, the researchers exposed MRSA bacteria to both a krypton-bromine excimer lamp, which would emit light at only the 207-nm wavelength,  as well as a standard germicidal lamp, which would emit light at the entire 200-400 nm range.

The team found that both lamps were just as effective at killing the bacteria.  However, the 207-nm lamp killed 1,000 times fewer skin cells.

In a separate experiment, the scientists tested the two UV lamps on a tissue-culture model of human skin, finding that, while the standard UV lamp created precancerous changes in the skin model, the 207-nm lamp did not.

Dr. Brenner says this wavelength of UV light is safer because it is not well-absorbed by proteins.  This means, first of all, that it cannot penetrate a cell’s nucleus and cause damage to its DNA.  Secondly, it is not able to reach the sensitive cells within the skin’s outer layer and the eye’s lens.

According to Dr. Brenner, despite all their best efforts, bacteria such as MRSA are still “raining down’ on the patient’s open wound during surgery.   Shining a 207-nm UV light on the entire area during a procedure could be the key to preventing such infections.

The team is now conducting studies using living tissues in the hopes of developing an inexpensive method which can be used to combat surgical infections.

The writeup on the current study was published online on October 16, 2013 in the journal PLOS ONE.

Written by:  Nancy Schimelpfening

Sources:

Narrow-Spectrum UV Light May Reduce Surgical Infections

Cataracts Causes – Mayo Clinic

Understanding UVA and UVB – Skin Cancer Foundation

 

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