Abstract
Introduction
Despite the routine use of irrigation, debridement and systemic antibiotics, there is a high incidence of infection in severe open fractures. The synergistic use of local and systemic antibiotics appreciably reduces infection rates although the time window within which this is effective is unknown. The aim was to determine if delaying treatment of wounds causes higher levels of infection.
Methods
A defect was created in the femurs of 90 Sprague-Dawley rats and inoculated with 105CFUs Staphylococcus aureus. At 2, 6 and 24 hours following contamination, the defect was irrigated and debrided. The experimental groups had either vancomycin or tobramycin impregnated PMMA beads placed within the segmental defect. The controls received no further treatment. Two weeks after wound closure, the bacteria within the femur were quantified.
Results
Delaying irrigation and debridement resulted in significantly more bacteria (p<0.01) within the control group (2 hr < 6 hr <24 hr). Both locally delivered tobramycin and vancomycin significantly reduced the bacteria (p<0.05) when administered at the earlier time points (2 and 6 hours). Locally-delivered antibiotics were ineffective when delivered at 24 hours.
Conclusion
Delaying treatment of contaminated defects reduces its effectiveness to eradicate infection. This is presumably because of the biofilm formation by the bacteria. Biofilms begin to form within a couple of hours and are mature within 12 hours. Early treatment of the wound allows the surgeon to physically remove the bacteria or have antibiotics present before a mature biofilm protects the bacteria.
