Antibiotic releasing urethane polymers for prevention of catheter related infections

In order to improve the resistance of catheters to microbial infections (particularly Staphylococci), a cephalosporin type antibiotic (cefamandole, CEF), and a glycopeptidic antibiotic (vancomycin), were adsorbed onto functionalized polyurethane films. The polymers were characterized by chemical, FT-IR and H-1-NMR analysis. The amounts of antibiotic adsorbed were higher than the ones reported in the literature. The kinetics of release, under standard conditions, was evaluated by in vitro tests; both the adsorption yield and the antibiotic release from the polymer surface depended on the type of the surface-antibiotic interactions. In particular, matrix hydrophilicity, formation of strong ionic bonds, existence of "spacing arms" between antibiotic and matrix bonding site play a role. The antimicrobial activity of the treated films was evaluated by optical microscopy and the Kirby-Bauer test. When exhausted polymer films, previously treated with CEF were submitted to a second adsorption, a superior antibacterial activity was observed.