Biodegradable alginate antibiotic beads

The authors investigated the poly-L-lysine-coated alginate beads as an anti biotic delivery system for the treatment of various surgical infections. Th e sodium alginate was mixed with vancomycin, coated with poly-L-lysine, and lyophilized to form five types of the biodegradable antibiotic beads. Type I, 2.5% alginate, nonpoly-L-lysine coated and nonlyophilized; Type II, 2.5 % alginate, poly-L-lysine coated but nonlyophilized; Type III, 2.5% algina te, poly-L-lysine coated and lyophilized; Type IV, 5% alginate, poly-L-lysi ne coated and lyophilized; and Type V, 7.5% alginate, poly-L-lysine coated and lyophilized, Cytotoxicity of the alginate beads to fibroblasts and HeLa cells was evaluated by the MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl- 2H tetrazolium bromide] colorimetric assay. A study of in vitro elution of vancomycin of the alginate antibiotic beads was performed. The results sug gested that the alginate antibiotic beads present no obvious toxic risk to their use as a drug delivery system. The concentration of vancomycin in the se five types of beads was well above the breakpoint sensitivity concentrat ion (the antibiotic concentration at the transition point between bacterial killing and resistance to the antibiotic) for 9,11,12, 14, and 17 days res pectively. The release was most marked during the first 3 days. The duratio n of antibiotic release was prolonged by using techniques of poly-L-lysine coating, lyophilization, and by increasing the content of alginate. This st udy offers a biodegradable delivery system of antibiotics to treat various surgical infections.