Hospitals and medical clinics can be the source of nasty infections, resulting in death from infection-related complications and billions in direct medical costs. The biggest culprits, experts say - accounting for two-thirds of these infections - are medical devices like catheters, stents, heart valves and pacemakers, whose surfaces often become covered with harmful bacterial films. Now, a novel surface treatment developed by scientists could help improve the safety of these devices and ease the economic burden on health care systems.

The new approach developed by a team of scientists at UCLA (Los Angeles, CA, USA) and tested in both laboratory and clinical settings, involves depositing a thin layer of what is known as zwitterionic material on the surface of a device and permanently binding that layer to the underlying substrate using ultraviolet light irradiation. The resulting barrier prevents bacteria and other potentially harmful organic materials from adhering to the surface and causing infection. In the laboratory, researchers applied the surface treatment to several commonly used medical device materials, then tested the modified materials’ resistance to various types of bacteria, fungi and proteins. They found that the treatment reduced biofilm growth by more than 80% - and in some cases up 93%, depending on the microbial strain.

The clinical research by the UCLA scientists involved 16 long-term urinary catheter users who switched to silicone catheters with the new zwitterionic surface treatment. Catheter-related urinary tract problems are illustrative of the issues plaguing other medical devices, which, once inserted or implanted, can become breeding grounds for bacteria and harmful biofilm growth. The pathogenic cells pumped out by these highly resilient biofilms then cause recurring infections in the body. In response, medical staff routinely adminster strong antibiotics to patients using these devices, a short-term fix that poses a longer-term risk of creating life-threatening, antibiotic-resistant “superbug” infections. The more widely and frequently antibiotics are prescribed, the more likely bacteria are to develop resistance to them.

Ten of the patients described their urinary tract condition using the surface-treated catheter as “much better” or “very much better,” and 13 chose to continue using the new catheter over conventional latex and silicone options after the study period ended. The surface treatment’s zwitterion polymers are known to be extremely biocompatible, and they absorb water very tightly, forming a thin hydration barrier that prevents bacteria, fungi and other organic materials from adhering to surfaces. The technology is highly effective, non-toxic and relatively low in cost compared with other current surface treatments for medical devices, like antibiotic- or silver-infused coatings. Beyond its use in medical devices, the surface treatment technique could have non-medical applications, potentially extending the lifetimes of water-treatment devices and improving lithium-ion battery performance.

“The beauty of this technology is that it can prevent or minimize the growth of biofilm without the use of antibiotics. It protects patients using medical devices - and therefore protects all of us - against microbial resistance and the proliferation of superbugs,” said Richard Kaner, UCLA’s Dr. Myung Ki Hong Professor of Materials Innovation and senior author of the research.

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