Blue light could be the key to defeating MRSA
Scientists in Boston, looking into new optical microscope techniques, have unexpectedly had the opportunity to break down MRSA’s surrounding membrane, using blue light.
Bacteria are impressively adaptive. Through rapid cell division and via horizontal gene transfer- where they transfer genes with their neighbors - bacteria can easily strengthen their defenses against threats.
One such threat is antibiotics, and pathogens, such as for example some bacteria, are rapidly adapting to defeat them.
As these pathogens become resistant to an increasing number of antibiotics, visions of a global where the drugs which we depend no longer work have seen scientists racing to come up with some other way to stop infections.
Now, scientists from Boston University’s College of Engineering in Massachusetts have announced success at weakening pathogens by using blue light to attack them on a molecular level.
Prof. Ji-Xin Cheng, from the faculty of Engineering, says that the “therapy is novel because, rather than utilizing a drug-based approach, it requires physical aim at the structure of the cell itself.”
Prof. Cheng is the senior author of a paper in Advanced Science that now describes the research.
A fortuitous accident
Prof. Cheng and his colleagues happened across blue light’s potential by accident, during experimentation with new optical microscope techniques.
They were using Staphylococcus aureus (S. aureus) as their microscopic subject but soon found it too unstable because of their purposes; the microscope’s blue light was bleaching the bacterium’s staphyloxanthin (STX) molecule.
“Golden pigmentation may be the universal signature of S. aureus,” says Prof. Cheng. “For imaging purposes, that is bad. But, if it’s bleached, we wondered, could it be still alive?”
The team was further surprised, and excited, to discover that their photobleaching finally caused their entire S. aureus colony to die. Having the capacity to kill S. aureus is no small thing.
S. aureus is arguably the clearest harbinger of an imminent postantibiotic era.
Methicillin-resistant S. aureus (MRSA) causes skin and soft tissue infections, sepsis, and pneumonia.
Methicillin was the first antibiotic to fail against MRSA, and the bacterium has since become extremely difficult to treat with other antibiotics, aswell.
In line with the Centers for Disease Control and Prevention (CDC), MRSA is responsible for most of the 2.8 million antibiotic resistant infections, and the 35,000 resulting deaths every year in the United States.
Confronted with the unexpected death of S. aureus, Cheng’s team found themselves wondering, “If we bleach [MRSA’s golden pigment], can we kill the [bacterium]?”
The response to the question turned out to be: “Almost.” It could be enough.
Blue light photolysis and MRSA
Further study revealed that whenever the microscope’s blue light photons broke down STX, small openings appeared all around the membranes protecting the MRSA cells, and 90% of the colony died.
However, when coping with a fast-moving bacterium like MRSA, that's not enough: Within half-an-hour, the cells were dividing again.
According to lead study author Pu-Ting Dong, “MRSA grows back very quickly, so to work, we have to kill 99.9% of bacteria.”
For the rest of the 10%, Cheng’s team tried something new: After blue light photolysis, which identifies the break down of molecules through light, they dosed the cells with hydrogen peroxide, a solid oxidizer that can attack living cells.
The hydrogen peroxide entered the S. aureus cells through the holes within their membranes, creating them to implode. Finally, they had destroyed 99.9% of the S. aureus colony.
Thus, blue light photolysis looks to be the first strike in a one-two punch that may remove antibiotic resistant pathogens.
Since their initial findings in the lab, Cheng and his team have partnered with researchers from Purdue University and Massachusetts General Hospital Wellman Center for Photomedicine in Boston to confirm the potency of their technique on MRSA skin wounds in mice.
Part of why is blue light photolysis so attractive, as a therapy, is that it generally does not damage normal cells.
This is also true of the blue light pulse laser therapy, which Cheng’s team has learned can provide even more effective photolysis. Study co-author Jie Hui explains:
“Utilizing a pulsing blue laser, we are able to significantly shorten the remedy time and increase the depth of tissues we can effectively treat. The laser light feels painless and doesn’t give off any sensation of heat, suitable for clinical applications.”
- Jie Hui
Next up for Cheng and colleagues is definitely the development of a trial for cure for folks with skin ulcers that diabetes causes.
“If we are able to treat diabetic ulcers,” he says, “which will change people’s lives. As scientists, we don’t just want to create papers, we also want to come back the fruits of our work and research funding to society.”
Source: www.medicalnewstoday.com
