Wound dressing to stop antibiotic-resistant bacteria from spreading

Sep 27 2005

University of Florida researchers have led the development of a new type of wound dressing that could keep dangerous antibiotic-resistant bacteria from spreading in hospitals, a problem that leads to thousands of deaths in the United States each year.

This microbicidal coating - which can be chemically bonded to gauze bandages, socks and even hospital bedding and gowns - kills the two most common and harmful types of antibiotic-resistant bacteria that cause infections in hospitals, the researchers said.

According to the National Institutes of Health, each year nearly 2 million Americans contract infections while hospitalized. Antibiotic-resistant bacteria, such as methicillin-resistant staphylococcus aureus and vancomycin-resistant enterococci, cause about 70 percent of those infections.

"Those are the two classes of bacteria that are now epidemic in the U.K.," said Gregory Schultz, Ph.D., director of UF's Institute for Wound Research and one of the inventors who joined with a Gainesville-based company to develop the coating. "It's a huge problem there."

A patent is pending on the researchers' method of chemically bonding the substance to fabrics and other materials. This method allows the substance to be efficiently mass produced and permanently adhered to wound dressings or ready-to-wear clothing to make antifungal and microbicidal socks and underwear.

"What we developed in the lab has to be able to be adapted into industrial manufacturing, and the breakthrough came when we figured out how to do that," Schultz said.

Clothing that kills athlete's foot and other fungi could help U.S. soldiers in the field who often don't have time to change or shower, and the substance also could be added to hospital gowns and bedding to stop the spread of resistant bugs, said Schultz, who also serves as the company's vice president of clinical research and development.

Developed as the ultimate wound dressing, the coating blocks bacteria from reaching a wound and recolonizing there. UF researchers and scientists from the company presented their findings at the Wound Healing Society's annual meeting earlier this year, and the coating's ability to wipe out harmful bacteria and fungi was later confirmed in independent laboratory tests.

The coating also was designed to keep bacteria from becoming resistant to it. Popular silver dressings work well as a bacterial barrier but release ions that allow resistance to develop, Schultz said.

The structure of the microbicidal coating and the complexity of the process make it nearly impossible for bacteria to become resistant to it, Schultz said. The coating comprises thousands of nitrogen clusters that permanently bond to substances such as gauze and fabric. Other dressings use a process that allows molecules to diffuse into the air and into the wound, which can slow healing and increases the chance germs will develop resistance.

"These technologies are especially timely given the threats that are facing the American public, such as antibiotic-resistant bugs occurring in hospitals across the world," said Christopher Batich, Ph.D., a UF professor of biomedical engineering and one of the coating's inventors. "This has the potential to be used widely."

The coating also does what it was created to do - aids healing, Schultz said. When added to gauze, it makes the material superabsorbent, pulling excess moisture away from the sore. And its microbicidal properties keep bacteria from growing in the wound and protect it from infections. Bacteria in a wound "is like jet fuel for these bugs," Schultz said.

"Gauze is still the most commonly used dressing for wounds," he said. "But the problem with gauze is when it absorbs fluid, it forms a great avenue for bacteria and fungus to grow. This treatment actually makes the gauze absorb a little more fluid, (but) it'll keep the wound cleaner because it will keep the bacteria from getting back into the wound."

Clinical trials of the coating in gauze will be conducted at UF later this year.

Controlling moisture and staving off infection are two of the most important aspects of wound healing, said Jeffrey M. Davidson, Ph.D., president of the Wound Healing Society and a Vanderbilt University professor of pathology.

"Control of infection is very important for any type of wound," he said. "Bacteria will produce substances that are harmful to the cells around them. They're trying to colonize. They're trying to make a home for themselves."