NEWS | June 19, 2017

NAMRU-SA researchers working on laser therapy project to improve treatment of drug-resistant wound infections

By David DeKunder 502nd Air Base Wing Public Affairs

An innovative project being conducted at the Naval Medical Research Unit San Antonio, or NAMRU-SA, at Joint Base San Antonio-Fort Sam Houston could lead to the development of laser therapy technology to improve the treatment of antibiotic resistant wound infections in the bodies of service members injured in combat.

The research project is aimed at studying the effectiveness of nanoparticle targeted laser therapy in weakening bacteria in wounds that contain biofilms, or a protective coating, that make infections highly resistant to antibiotics or other types of drugs needed to treat the wound and fight the infection.

Dr. Nancy Millenbaugh, research chemist and principal investigator for the Craniofacial Health and Restorative Medicine Directorate at NAMRU-SA, said the research she is conducting into laser therapy is focused on ways to enhance the treatment of maxillofacial wound infections, including methicillin-resistant Staphylococcus aureus, or MRSA, infections of soldiers who are injured on the battlefield.

Maxillofacial wounds affect the face and the jaw. Many service members with maxillofacial wounds were injured by an improvised explosive device, or IED, while serving in Iraqi or Afghanistan.

Biofilm infections that form in wounds can lead to scarring and extended hospital stays, delaying the return of servicemembers to duty, and sometimes death. Millenbaugh said 80 percent of all infections in the body are linked to chronic wounds with biofilms covering them.

Millenbaugh said the battlefield is a place where wound infections resistant to antibiotic treatment are able to form because of adverse conditions, including contaminants from the ground, clothing and wood.

“It’s a horrible, dirty environment,” Millenbaugh said. “They (service members) get a lot of contamination from the environment and from organisms on the body in their wounds. Especially, the severely wounded service members develop really nasty infections. Their immune systems are affected so they can’t fight these infections. These turn into chronic infections that take a long time to heal.”

The organisms in the wound have genetic mechanisms that develop over time to make them resistant to antibiotics, for example by pumping antibiotics out of the bacteria.

Millenbaugh and her team of researchers at NAMRU-SA have performed experimental gold nanoparticle, or GNP, laser therapy that has been effective in breaking up biofilms. A GNP is a microscopic particle of matter that behaves as a whole unit with respect to its transport and properties, according to (http://)

The experimental GNP targeted laser therapy involves growing samples of biofilms on a culture plate, or in vitro models. GNPs, which have antibodies chemically attached to their surface, are then put on the biofilm and allowed to incubate. The attached antibodies target the particles to the bacteria and biofilm matrix.

Once the targeted particles become attached to the bacteria or biofilm matrix, Millenbaugh said the exposed wound infection is then exposed to a pulsed laser. The GNPs have a property called surface plasmon resonance that causes them to acts as an antenna in absorbing the laser energy beam, which is then focused on the bacteria.

Millenbaugh explained what happens when the GNP absorbs the laser energy and hits the bacteria.

“The GNP heats up very rapidly, very high on the surface close to the bacteria or biofilm,” she said. “This causes thermal damage to any components it is in contact with. It’s going to breakdown the bacterial cell. It will breakdown the biofilm and disperse the biofilm. It is basically blasting it apart.”

Once the biofilm is broken down or dispersed, an antibiotic or other drug can then penetrate and get through to the bacteria treat the wound infection, Millenbaugh said.

NAMRU-SA has been testing and studying laser therapy techniques against bacterial biofilms for two years. Since researchers have proven that laser therapy is effective against in vitro models of MRSA and multi-drug resistant biofilms, NAMRU-SA has received additional funding to continue research for laser therapy experiments.

Millenbaugh said laser therapy has the potential to improve the quality of treatment for servicemembers injured in battle.

“Severely wounded servicemembers who have these chronic wounds due to multi-drug resistance and biofilms would really benefit from this,” Millenbaugh said. “This would enhance the treatment, it could shorten the recovery period, it could shorten hospital stays, it could prevent recurrent infections and it could get them back onto the battlefield and back in service more quickly.”

Also, laser therapy could be utilized for patients with diabetes, who have implant or medical devices, or catheters. Biofilm infections can develop in all three of these conditions, causing chronic wounds and in some instances, blockage for catheter users.

“In chronic wounds associated with biofilms, this therapy could be utilized during wound debridement to enhance removal of infectious material and recalcitrant biofilms,” Millenbaugh said.

Millenbaugh said any laser therapy treatment that is developed would need approval from the Federal Drug Administration before it can be used to treat patients. She anticipates it would take 10 to 15 years of research to get FDA approval.