Antibacterial plastics a lethal weapon in fight against superbugs

By: 
February 19, 2015

The antibiotic apocalypse that the World Health Organization, the Centers for Disease Control and Prevention and sundry medical professionals have been warning about came into sharp focus this morning, when the Los Angeles Times reported that as many as 180 patients may have been exposed to potentially deadly bacteria while being treated at the UCLA Ronald Reagan Medical Center. Two deaths have been linked to the outbreak thus far.

The cause of the outbreak appears to be a type of endoscope, called a duodenoscope, that is used to treat cancers, gallstones and other digestive conditions. The design of this particular device, which is different from instruments used in routine endoscopies and colonoscopies, makes it difficult to disinfect. As raps.org reports in an article published today, "Unlike most other endoscopes, duodenoscopes also have a movable 'elevator' mechanism at the tip . . . . The elevator mechanism changes the angle of the accessory exiting the accessory channel, which allows the device to be much more nimble and useful."

Raps.org continues: "As a recent USA Today investigation found, while the innovative design of the device makes it more effective, it also makes it considerably more difficult to clean. The device has been associated with the transmission of carbapenem-resistant Enterobacteriaceae (CRE), a hardy and potentially deadly bacterium." And that, apparently, is precisely what happened at the UCLA medical center.

CRE is resistant to antibiotics and if the infection spreads to the bloodstream, it can be fatal in up to 50% of patients.
UCLA discovered the outbreak last month while running tests on a patient, reports the Los Angeles Times, and began notifying 179 other patients who were treated and may be infected last week. Thus far, seven patients were found to have been infected, including the two that have died.

FDA issued a warning today in which it "seeks to raise awareness among healthcare professionals . . . that the complex design of ERCP endoscopes (also called duodenoscopes) may impede effective reprocessing. Meticulously cleaning duodenoscopes prior to high-level disinfection should reduce the risk of transmitting infection, but may not entirely eliminate it," noted the agency.

More than 500,000 ERCP procedures using duodenoscopes are performed in the United States annually, according to FDA.

Since the so-called superbugs are resistant to the arsenal of drugs available today, it's imperative that medical device manufacturers and practitioners take every precaution to prevent opportunities for the bacteria to gain a foothold in the first place. Antibacterial materials have a role to play in that.

Emerging and current technologies in antibacterial materials

Earlier this week, PlasticsToday reported that researchers at the Wyss Institute for Biologically Inspired Engineering (Boston) have developed polymers that can store considerable amounts of lubricating liquids within their molecular structure and release them over time to render the material continuously slippery and repellant to bacteria. The polymer could prevent biofilms—colonies of bacteria that form on medical devices—from establishing a presence.

Meanwhile, a team of researchers from A*STAR (Agency for Science, Technology and Research) in Singapore, Nanyang Technological University and City University of Hong Kong have produced a material that not only repels bacteria but also attracts healthy cells. Implants would be the primary application of the thin-film coating, which is currently at the proof-of-concept stage and, thus, won't be available clinically for some years. The first results of the material's performance are published in the Institute of Physics (IOP) Biomedical journal. It works essentially by helping healthy cells win the race to the implant surface, which can then fend off the bacterial cells.

The base of the material is made from polyelectrolyte multilayers onto which a number of specific bonding molecules, called ligands, are attached, according to IOP. "After testing various concentrations of different ligands, the researchers found that RGD peptide was particularly effective at inhibiting the attachment of bacterial cells and attracting healthy cells, compared with collagen, when attached to dextran sulfate and chitosan multilayers," writes IOP.

Over at Parx Plastics (Rotterdam, Netherlands), antibacterial plastics have left the lab and are ready for prime time. The company has been named one of Europe's top three startups by the European Commission and received the 2014 World Technology Award in such august company as Tesla founder Elon Musk and Oculus visionary Palmer Luckey. The reason for the well-deserved accolades is the development of a biocompatible material that can be integrated into a wide range of plastics to inhibit the growth of bacteria for the life of a product. Sanipolymers are devoid of harmful substances, and the material will not leach or degrade. Bacterial reduction in materials containing the antimicrobial and antibacterial technology is on the order of 99% and greater based on the ISO 22196 standard, according to the company.

Company co-founder Michael van der Jagt told sister brand emdt that he and his team are currently working on a number of applications for medical devices, but he couldn't disclose any details. He did suggest one possible application where the technology could provide a major benefit: Surgical meshes.

"Looking at hernia meshes, for example, [infections pose] the biggest threat to the patient. It will take eight to 12 months and multiple surgeries to recover from it. If we can reduce the chance that this occurs, the cost advantage is huge," van der Jagt said to emdt. "But also benefits can be identified when applying the technology to hospital interiors, medical device casings, wound dressings, surgery aprons, IV lines, dialyses machines, et cetera," he said.

Product design and not the material apparently is to blame for the superbug infection at the UCLA medical center. But given the potential devastation that antibiotic-resistant bacteria can cause, it's important to use every resource at our disposal to prevent their propagation. Thanks to their incredibly malleable properties, polymers are on the front lines of this battle.

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