Rifampicin-eluting biodegradable PLGA coatings can significantly inhibit in vitro biofilm formation for 10 weeks

Biofilm infection is a challenging complication of implanted medical devices due to difficulties in delivering a concentrated dose of antimicrobial to the infection site. To prevent biofilm pathogenesis, a local drug-delivery method, such as drug-eluting technology using biodegradable polymers to coat implantable devices, may be favourable.

Implantable medical-grade polyester was coated in formulations of Poly(lactic-co-glycolic acid) and rifampicin (50:50, 60:40) and placed in PBS (37°C; 120rpm). To characterise release, media was collected periodically over 10 weeks and analysed (UV-spectrophotometry; 334nm). To examine biofilm inhibition, material was removed and submerged in Staphylococcus aureus and Escherichia coli suspensions (37°C; 24hrs) to stimulate biofilm formation. Biofilms were recovered using agitation/sonication, and enumerated.

Release data revealed that both formulations had an initial burst-release phase during the first 24 hours, releasing 92% (50:50) and 88% (60:40) of their respective rifampicin loads. For both formulations, this was followed by slow-release for the remainder of the examined time, reaching 98.9% (50:50) and 97.9% release (60:40). Despite a small fraction of loaded rifampicin remaining, the formulations were able to significantly inhibit S. aureus biofilm formation (up to 99%) for 10 weeks, and E. coli biofilm formation (up to 57%) for 6 weeks.

Drug-eluting polymer technology has already seen success in medical devices, such as coronary stents, to prevent restenosis. Here it has been indicated that this technology has potential in the field of infection prevention, by demonstrating the ability to inhibit in vitro biofilm formation to a significant degree for up to 10 weeks.