Most animal studies indicate that early irrigation
and debridement reduce infection after an open fracture. Unfortunately,
these studies often do not involve antibiotics. Clinical studies
indicate that the timing of initial debridement does not affect
the rate of infection but these studies are observational and fraught
with confounding variables. The purpose of this study was to control
these variables using an animal model incorporating systemic antibiotics
and surgical treatment. We used a rat femur model with a defect which was contaminated
with No animal that received antibiotics and surgery two hours after
injury had detectable bacteria. When antibiotics were started at
two hours, a delay in surgical treatment from two to six hours significantly
increased the development of infection (p = 0.047). However, delaying
surgery to 24 hours increase the rate of infection, but not significantly
(p = 0.054). The timing of antibiotics had a more significant effect
on the proportion of positive samples than earlier surgery. Delaying
antibiotics to six or 24 hours had a profoundly detrimental effect
on the infection rate regardless of the timing of surgery. These
findings are consistent with the concept that bacteria progress
from a vulnerable planktonic form to a treatment-resistant biofilm.