Light: Enemy of Vampires and…Bacteria?

Jun 8, 2012 | Adham Abdel Mottalib | Research & Policy

Since the discovery of penicillin by Alexander Fleming in 1928, scientists have been involved in a hectic battle against bacteria, which in turn have been continuously evolving to develop resistance to different kinds of drugs.

Researchers from University of California, Santa Cruz, developed a novel technique to eradicate a highly drug resistant strain of the Acinetobacter baumannii bacteria using nitric oxide. This gram-negative bacterium is the cause of many difficult-to-treat infections including those affecting soldiers wounded in Afghanistan and Iraq, hence its nickname “Iraqibacter”.

Nitric oxide is a chemical involved in many normal body functions as well as disease processes. Besides being a strong dilator of the blood vessels (which allows an increased blood flow), it is known to promote immune system function and wound healing. It is particularly useful because it is difficult for bacteria to develop resistance against it. Nitric oxide attacks a range of targets in bacteria, including DNA, cell wall lipids, proteins and enzymes. In order for bacteria to develop resistance, it would have to change at each of those attack sites. In its gaseous form, nitric oxide has been used to treat infected wounds. However, the gaseous form remains very difficult to handle because it is toxic and highly unstable.

The UCSC researchers, led by Dr. Pradip Mascharak, developed a method of delivering the nitric oxide molecule that eliminates these challenges. The technique is based on a newly developed light sensitive compound that contains both a nitric oxide particle and a carrier molecule that helps deliver nitric oxide to the tissues. This compound rapidly releases nitric oxide when exposed to light and the nitric oxide kills the drug resistant bacteria. Just as light is instrumental in killing vampires, it is now instrumental in killing drug resistant bacteria. "We think it could be used as a sprayable powder for treating battlefield wounds" says Dr. Pradip Mascharak, Professor of chemistry and biochemistry and leader of the research team. The superior advantage of this is the ability to control the release of nitric oxide. Tests proved that illumination of the material causes a steady release of nitric oxide, which can be stopped and started repeatedly by turning the light off and on. When in the field, of course, soldiers could apply this easy-to-use spray powder and leave the wounded area uncovered, to be activated by light.

This novel approach proved to be effective against bacteria in laboratory tests. The research team now hopes to find collaborators willing to take this technique to the next level of clinical testing to assess the effectiveness of the compound.

written by Adham Abdel Mottalib

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