Blue Light Zaps Infection

Blue light can destroy antibiotic-resistant staph infection (Staphylococcus Aureus), according to a recently published paper.

Two common strains of methicillin-resistant Staphylococcus Aureus, commonly known as MRSA, were virtually eradicated in the laboratory by exposing them to a wavelength of blue light, in a process called photo-irradiation.

Antibiotic-resistant bacterial infections represent an important and increasing public health threat. At present, fewer than 5 percent of staph strains are susceptible to penicillin, while approximately 40-50 percent of staph infections isolated have developed resistance to newer semisynthetic antibiotics such as methicillin as well.

Chukuka S. Enwemeka, Deborah Williams, Sombiri K. Enwemeka, Steve Hollosi, and David Yens from the New York Institute of Technology in Old Westbury, NY, had previously demonstrated that photo-irradiation using 405-nm light destroys MRSA strains grown in culture. In the current study, "Blue 470-nm Light Kills Methicillin-Resistant Staphylococcus Aureus (MRSA) in Vitro," the authors exposed bacterial colonies of MRSA to various doses of 470-nm light, which emits no ultraviolet radiation.

The two MRSA populations studied – the US-300 strain of CA-MRSA and the IS-853 strain of HA-MRSA – represent prominent community-acquired and hospital-acquired strains, respectively.

The authors report that the higher the dose of 470-nm blue light, the more bacteria was killed. High-dose photo-irradiation was able to destroy 90.4 percent of the US-300 colonies and the IS-853 colonies. The effectiveness of blue light in vitro suggests that it should also be effective in human cases of MRSA infection, and particularly in cutaneous and subcutaneous infections.

"It is inspiring that an inexpensive naturally visible wavelength of light can eradicate two common strains of MRSA. Developing strategies that are capable of destroying MRSA, using mechanisms that would not lead to further antibiotic resistance, is timely and important for us and our patients," said Enwemeka.

The paper will be published in the April 2009 issue of Photomedicine and Laser Surgery, and is currently available online at www.liebertpub.com/pho