The effect of
antibiotic bead chains on the evolution of
infection cannot be studied entirely in man due to the ethical problems of obtaining valid controls. Therefore, a model of musculoskeletal injury was devised in rabbits by making a paraspinal
wound, fracturing a spinous process, and contaminating the
wound with 1 x 10(4) colony-forming units/ml of Staphylococcus aureus. These contaminated
wounds were treated with
tobramycin-containing
polymethylmethacrylate (
PMMA) beads. Control rabbits were either treated with
PMMA beads that did not contain
antibiotic, treated with IM
tobramycin, or left untreated. At 5 days, six of eight animals treated with
antibiotic-impregnated beads had no recoverable organisms. Six of eight rabbits receiving IM
tobramycin had
wound infections, and five of five in whom non-
antibiotic-containing beads had been implanted had significant
wound infections, with one of the five dying of
sepsis on the 3rd day of the experiment. The
clinical course of infected controls was the same as the course of those animals receiving IM
antibiotics and the same as those in whom beads without
antibiotics were implanted. That is, the rabbits had grossly infected
wounds and the organisms recovered were of the same type as those implanted. This research shows a highly statistically significant effect of
tobramycin-containing
antibiotic beads in retarding the evolution of an experimental Staphylococcus
infection in rabbits.