Experimental models to prevent microbial colonization of intravascular catheters and related infections.

Local or systemic infections are frequently associated to the use of intravascular catheters. The significant increase in the type of nosocomial infection has promoted the search for new strategies to prevent them. Our study is focused on the development of in vitro models to prevent catheter-related infections based on the adsorption of antibiotic molecules on polyurethanes, the mainly employed polymers for catheter fabrication. The four antibiotics experimented were: cefamandole nafate, amoxicillin, rifampin and vancomycin. To improve the antibiotic-polymer affinity, and consequently to increase the amount of antibiotic adsorbed, a polymer provided with suitable functional groups (tertiary ammine) able to interact with the acidic groups of the above listed antibiotics was tested. The influence of the strength of polymer-drug interaction on the antibiotic adsorption and on the kinetics of antibiotic release was evaluated. The antibacterial activity of the polymer-antibiotic systems realized in terms of their antibacterial efficacy was evaluated in vitro by the Kirby Bauer test, by employing the strain ATCC 35984 of Staphylococcus epidermis ad susceptible microorganism. The polymer-antibiotic systems set-up inhibited bacterial colonization and showed antibacterial activity lasting from five hours (amoxicillin) to eight months (rifampin) according to the specific antibiotic. The promising results obtained till now open new perspectives in the application of this type of systems in the production of medical devices able to avoid microbial colonization.