The use of biodegradable amikacin microspheres to prevent vascular graft infection.
The following study was performed to determine if an antibiotic impregnated in a biodegradable polymer can prevent infection and eradicate inoculum bacteria from contaminated polytetrafluoroethylene vascular grafts. Poly(glycolide-co-dl-lactide) amikacin microspheres (PAM) measuring 50-100 microns were designed to deliver 100 mg (PAM 100) or 300 mg (PAM 300) amikacin per unit dose. Twenty mongrel dogs had a short segment of infrarenal aorta replaced with a graft that had been bathed in a 2 cc solution of Escherichia coli and Staphylococcus aureus (3 x 10(8) CFU/ml). Dogs were divided into three groups: Controls had contaminated grafts placed and received no therapy; PAM 100 and PAM 300 were used, respectively, to cover the grafts in the other two groups. Animals were sacrificed 14 days postoperatively at which time grafts were examined and cultured. Among controls, 7/8 had clinical graft infections and all had positive cultures for S. aureus (8/8) or E. coli (5/8). None of the treated animals had clinical graft infections (P < 0.001). Positive cultures were obtained for S. aureus in 2/8 (P < or = 0.007) and E. coli in 0/8 (P < or = 0.03) PAM 100 dogs and for S. aureus in 0/8 (P < or = 0.0002) and E. coli in 0/8 (P < or = 0.03) PAM 300 dogs. Two PAM 100 and four PAM 300 dogs had rare growth of contaminant bacteria (NS). In conclusion, PAM can prevent clinical graft infection and completely eradicate a standardized bacterial inoculum.