INDUSTRY NEWS
In recent years, there has been a substantial growth in the number of hospital-acquired infections globally—a problem that has become especially worrisome as antibiotic resistance worsens. Medical devices have been implicated as part of the problem, because, after they are removed from their sterile packaging, they can transmit bacteria found in the air or on a patient’s skin. “Contaminated medical devices such as catheters and implants cause more than 50% of hospital-acquired infections,” notes Jeffrey Dabkowski, a microbiology graduate researcher in microbiology at the University of Massachusetts in Amherst, MA, USA. “The best way to combat this problem is to create surfaces that inhibit bacterial growth upon exposure,” he says. To that end, Dabkowski and other researchers at the university have worked under the tutelage of professors Gregory N. Tew and Klaus Nüsslein to develop a variety of polymers that quickly kill bacteria and other microbes on contact. Unlike antibiotics, the polymers avoid the problem of antibacterial resistance.
The inspiration for the polymers came from a diverse class of naturally occurring antimicrobial agents known as host defense peptides. “The materials’ antibacterial action results from their ability to directly interact with the bacteria’s outer surface,” Dabkowski explains. While the exact nature of this interaction remains under investigation, he believes that the potency of the host defense peptide-like antibacterial polymer stems from its affinity towards the negatively charged bacterial cell membranes, which kills bacteria by disrupting their cell equilibrium, yet remains nontoxic to human cells.
The group decided to test the efficacy of one of the polymers by spraying it with a solution containing S. aureus—a gram-positive bacterial strain that is one of the most common sources of hospital-acquired infections. Using microscopy, the group observed that 100% of the bacteria was killed two minutes after contacting the polymer. The material continued to display strong antibacterial properties after as many as 15 exposures. The researchers also found that the polymer was effective against gram-negative bacteria such as E. coli.
“While silver has gained much popularity as an antibacterial agent, our polymers operate through novel pathways that allow greater specificity for bacteria over mammalian cells,” Dabkowski explains. “The widespread implications from the use of heavy-metals as antibacterial agents, including silver, is unclear,” he adds. Conversely, the polymers that the group developed are constructed from elements common to organic, living systems such as carbon, hydrogen, and nitrogen. While the polymer has not yet been used in implants, similar materials have shown excellent tolerance in a variety of animal studies.
Dabkowski says that it is hard to predict when the polymer might be ready for the market, but he expects that demand for new antibacterial materials will accelerate market approval. “With increasing bacterial resistance, there will be strong demand for new antibacterial technologies.” In the meantime, the research group plans on refining the antimicrobial activity and elucidating the polymer’s antimicrobial action.
