EFFECT OF SYSTEMIC ANTIBIOTIC AND ANTIBIOTIC-IMPREGNATED POLYMETHYLMETHACRYLATE BEADS ON THE BACTERIAL CLEARANCE IN WOUNDS CONTAINING CONTAMINATED DEAD BONE

A dorsal muscular wound model was used in 40 New Zealand White rabbits to study the effect of systemic and local antibiotics on the bacteria l clearance of contaminated dead bone. Devitalized iliac crest bone pr eincubated with Staphylococcus aureus was implanted in each deep muscu lar wound with or without tobramycin-impregnated polymethylmethacrylat e beads. Either systemic tobramycin or cefazolin was administered for 7 days. Animals were sacrificed at 7 and 14 days. The wounds containin g tobramycin beads had significantly fewer bacteria than those without antibiotic beads (2.0 x 10(2) versus 1.3 X 10(6); p < 0.008). The red uction in bacteria due to the tobramycin beads did not differ signific antly with respect to the concurrent systemic antibiotics or to the du ration of incubation. We conclude that tobramycin-impregnated beads ar e effective in reducing bacterial count in contaminated bony wounds tr eated with systemic antibiotics. Furthermore, the bactericidal effect of the antibiotic beads is independent of and additive to the systemic antibiotic delivered to the wounds by well-perfused muscles.