Study: Using Blue Light For MRSA Treatment

Study: Using Blue Light For MRSA Treatment

Bacteria are very adaptive. They can make defense against threats for them by cell division and horizontal gene transfer.

One example of threat for bacteria is antibiotic. However, bacteria are adapting themselves to defeat.

As bacteria becomes resistant to these antibiotics, the world which depends on them to fight bacteria will be under threat. These drugs will no longer be useful against infections and scientist would have to come up with new ways to fight them.

Recently, scientists at Boston University’s College of Engineering in Massachusetts have got success in weakening the pathogens using a blue light at molecular level.

Prof. Ji-Xin Cheng says the “therapy is novel because, instead of using a drug-based approach, it takes physical aim at the structure of the cell itself.”


The founding was result of an accident. The researchers were using Staphylococcus aureus (S. aureus) as microscopic subject but this was unstable for their project. The microscopes blue light was bleaching the bacterium’s staphyloxanthin (STX) molecule.
Prof. Cheng told “golden pigmentation is the universal signature of S. aureus, for imaging purposes, this is bad. But, if it’s bleached, we wondered, is it still alive?”

The team found that their photobleaching killed the whole S. aureus colony. Killing S. aureus is not a common thing. S. aureus is arguably the clearest harbinger of an imminent postantibiotic era.

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Methicillin-resistant S. aureus (MRSA) causes skin infections and pneumonia. It is named “Methicillin-resistant” because Methicillin was the first antibiotic which failed to kill it. Since then bacterium has become very difficult to destroy with other antibiotics too.

According to Center for Disease Control and Prevention (CDC) MRSA causes 2.8 million antibiotic resistant infections and results in 35,000 deaths in America every year.

With the unexpected results, Prof. Cheng and his team are taking the question “can bleach kill the bacterium?”. The answer is “Almost”. It may be enough.

Initial Results:

Further study found that microscope’s blue light photons broke STX. When it was broken, little openings appeared on the surface of the membrane which protects the MRSA. About 90% of the colony died when the protection was broken.

90% of them died, and this isn’t all. Within 30 minutes, MRSA started dividing again. According to Pu-Ting Dong, “MRSA grows back very quickly, so to be effective, we need to kill 99.9% of bacteria.”

Killing remaining 10% of S. aureus:

After killing the 90%, there must be something else to kill the remaining 10%. To do so, Prof. Cheng’s team used hydrogen peroxide, a strong oxidizer which can attack living cells.

There were already holes in the membrane surface. Hydrogen peroxide entered S. aureus from these holes and caused them to implode. Ultimately, 99.9% of the S. aureus was killed.

Thus, blue light photolysis looks to be the first strike in a one-two punch that can take out antibiotic resistant pathogens.

Research Continued:

After the initial findings, Cheng’s team collaborated with researchers at Purdue University and Massachusetts General Hospital Wellman Center for Photomedicine, Boston, for further research. The team is now testing on the mice wound skin for the effectiveness of the technique.

Blue light therapy seems to be very useful as there is no effect of the light on the normal cells.

Jie Hui, co-author of the study, said “using a pulsing blue laser, we can significantly shorten the therapy time and increase the depth of tissues we can effectively treat. Laser light feels painless and doesn’t give off any sensation of heat, ideal for clinical applications.”

Future Work:

The Cheng’s team is up to develop treatment for skin ulcers caused by diabetes.

“If we can treat diabetic ulcers, that will change people’s lives. As scientists, we don’t just want to publish papers, we also want to return the fruits of our work and research funding to society,” Prof. Cheng says.

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