RESUMO
OBJECTIVE: To develop a biodegradable, modified-release antibiotic pellet capable of eradicating biofilms as a potential novel treatment for biofilm infections. DESIGN: Pellets containing poly(DL-lactic-co-glycolic acid) microparticles, rifampin and clindamycin hydrochloride (3.5%, 7%, or 28% antibiotic by weight), and carrier gel (carboxymethylcellulose or poloxamer 407) were tested in vitro. Drug release was assessed using serial plate transfer testing and high-performance liquid chromatography, and pellets were tested against biofilms in an in vitro model of Staphylococcus aureus biofilm grown on silicone. RESULTS: Serial plate transfer testing demonstrated continuing bacterial inhibition for up to 21 days for all pellets studied. High-performance liquid chromatography showed high levels of drug release for 2 to 4 days, with greatly reduced levels subsequently; continued measurable clindamycin (but not rifampin) release for up to 21 days was achieved. Pellets made with poloxamer released higher drug levels for a longer period. Irrespective of the carrier gel used, pellets containing 7% and 28% (but not 3.5%) antibiotic eradicated biofilms successfully. CONCLUSIONS: Antibiotic pellets can release antibiotics for up to 21 days and are able to eradicate biofilms in an in vitro model. Use of modified-release antibiotic formulations in the middle ear as a treatment for biofilms appears to be a potentially promising new therapy for otitis media with effusion.