Biodegradable polymer drug delivery technology to prevent implanted medical device infection

Infection of in-dwelling medical devices, predominantly caused by Staphylococcus species, can be particularly problematic when pathogenesis involves formation of a biofilm. Consequences of an infection can be severe, often requiring device removal due to the difficulties in delivering a dose of antimicrobial high enough to eradicate a biofilm at the site of infection - this is complicated further if the device in question is not designed to be easily removed. There is currently much focus on the development of methods for prevention of device-related infections, and biodegradable polymer drug delivery technology has great potential for this application. In this study, the polymer PLGA (Poly(D,L-lactic-co-glycolic acid(65:35)) has been formulated with the broad spectrum antibiotic rifampicin, at ratios 50:50 and 60:40 PLGA:rifampicin, and the in vitro drug release and antimicrobial activity analysed. The formulations were coated on glass coverslips and stored in PBS at 37°C; 120rpm. Over a period of 4 weeks both formulations steadily released the majority of their drug load (>94%), and were able to produce large zones of inhibition against S. aureus (>34mm) in a disk diffusion test. Furthermore, both formulations successfully inhibited in vitro biofilm formation when compared to PLGA alone with a 5 log reduction in CFU/ml (99.999%). The results of this study indicate that biodegradable polymers could potentially be used for delivering a high local dose of antimicrobial at device implant sites, and may therefore represent a promising method for infection prevention.