THE EFFECTS OF POLYHEMA COATING ON THE ADHESION OF BACTERIA TO POLYMER MONOFILAMENTS

Bacterial adhesion to implants is the initial stage in the pathogenesis of device-related infections, the extent of attachment being dependent on the surface properties of both the bacteria and the substrate. One approach to preventing infection involves incorporating antiadhesive agents onto the surface of indwelling devices. Hydrogels of poly(2-hydroxyethylmethacrylate) (polyHEMA) homopolymer have been shown previously not to support the attachment and growth of mammalian cells but their interaction with bacterial cells has not been extensively investigated. The purpose of this study was to modify the surfaces of polymeric monofilaments by coating them with polyHEMA, and then test their ability to support bacterial attachment before and after coating. Monofilaments composed of polyester, polyvinylidene chloride (PVDC) and nylon were dip-coated in a 5% (w/v) polyHEMA solution in 95% (v/v) ethanol. Work of adhesion (WA) was determined from determination of the contact angle between the monofilaments and water. Adhesion of E. coli was assessed using a bioluminescent method based on adenosine triphosphate determination and scanning electron microscopy was used to investigate the surface morphologies of the monofilaments. Coating the monofilament fibres with polyHEMA increased the value of WA from 100.6, 94.6 and 91.2 mJ m-2 for PVDC, polyester and nylon, respectively, to a common value of 113.7 mJ m-2, indicating that the monofilaments were more hydrophilic after coating. Adhesion of E. coli cells to all monofilaments occurred rapidly and was almost complete after 2 h incubation. The coating of the monofilaments with polyHEMA reduced the surface rugosity of the monofilaments and significantly reduced the numbers of adherent bacteria. The modification of the surface in this manner is likely to have implications for situations where bacterial adhesion is a factor in predisposing infection.