Blue light destroys antibiotic-resistant staph infection

WASHINGTON, Jan. 29 (Chinese media) -- Two common strains of

methicillin-resistant Staphylococcus aureus, commonly known as MRSA, were

virtually eradicated in the laboratory after being exposed to a wavelength of

blue light, according to a paper published online on Thursday ahead of print in

Photomedicine and Laser Surgery.

Antibiotic-resistant bacterial infections represent

an important and increasing public health threat. At present, fewer than 5

percent of staphylococcal strains are susceptible to penicillin, while

approximately 40 percent to 50 percent of Staph aureus isolated have developed

resistance to newer semisynthetic antibiotics such as methicillin as well.

Researchers from the New York Institute of Technology

had previously demonstrated that a process called photo-irradiation using 405-nm

light destroys MRSA strains grown in culture. In the current study, the authors

exposed bacterial colonies of MRSA to various doses of 470-nm light, which emits

no UV 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 were 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," says Chukuka S. Enwemeka, first author of the study.