Using an experimental rabbit model of a contaminated open fracture of
the tibia that was fixed with an intramedullary pin, we assessed the effect
of a single dose of cephradine in preventing post-traumatic osteomyelitis
in which the infecting organism was Staphylococcus aureus. We paid
particular attention to the effect of a delay in giving the antibiotic. The
frequency of osteomyelitis in the animals in a control group (no
antibiotic) was 91 per cent. When a single injection of cephradine was
given one hour before inoculation with the bacteria, the rate was 30 per
cent, a statistically significant reduction (p less than 0.01). When
cephradine was not administered until one to four hours after inoculation
with the bacteria, the average rate of osteomyelitis was 51 per cent, a 40
per cent reduction compared with the rate for the control group. The effect
of the antibiotic therefore persisted even when the initial dose was
delayed for four hours after bacterial inoculation.