Hospital-acquired infections are a serious problem, and the most common type of such infections occurs when catheters are inserted into blood vessels. A new coating, however, shows promise for killing bacteria at insertion sites, keeping them from establishing biofilm colonies on the catheters.

Developed at Rhode Island's Brown University, the coating was created by first dissolving polyurethane and concentrations of an antibacterial drug known as auranofin, then mixing them into a solvent solution. The resulting liquid was subsequently applied to a catheter, after which the solvent was evaporated away. This left a durable polymer coating behind, which can stretch by up to 500 percent without breaking.

In lab tests, catheters treated with the coating were placed in solutions and on glass plates, in which harmful methicillin-resistant Staphylococcus aureus (MRSA) bacteria was present. For up to 26 days, the coating gradually released auranofin, inhibiting MRSA growth on the catheter – this kept the bacteria from forming difficult-to-remove biofilms.

By contrast, when a traditional antibiotic was tested under the same conditions, it was unable to keep biofilms from forming. What's more, because auranofin isn't an antibiotic, there's no risk of its use leading to the development of antibiotic-resistant bacteria.

Tests additionally indicate that the coating has no adverse effects on human blood or liver cells, although further research will be required before human trials can begin.

"Biofilms have really effective ways of evading antibiotics, which makes them thousands of times more difficult to treat in terms of the concentration of drug needed compared to planktonic [free-floating] bacteria," says Asst. Prof. Anita Shukla, corresponding author of a paper on the research. "The fact that these coatings are able to prevent biofilms from forming in the first place is really important."

The paper was recently published in the journal Frontiers in Cellular and Infection Microbiology. Brown's Eleftherios Mylonakis and Beth Fuchs also took part in the study.

Scientists at other institutes have previously explored the use of UV-emitting fibers, bioactive glass and iron oxide nanoparticles for keeping catheters biofilm-free.