Background: Since device colonization is a prelude to infection, an
antimicrobial-coated device that reduces bacterial colonization can
potentially protect against infection. The objective of this animal study was
to assess the efficacy of a coating with minocycline and rifampin to prevent
colonization of a grit-blasted titanium implant and subsequent
Methods: Twenty-five rabbits underwent implantation of a
titanium-alloy pin, either coated with minocycline and rifampin (thirteen
rabbits) or uncoated (twelve rabbits), into the right femoral medullary canal.
The implanted devices were inoculated with 500 CFU (colony-forming units) of
Staphylococcus aureus prior to wound closure. The rabbits were killed
one week later, and the removed device, femoral bone, a specimen obtained by
swabbing the track surrounding the device, and blood were cultured. The rates
of device colonization, osteomyelitis, and device-related osteomyelitis were
compared between the two groups of rabbits.
Results: The antimicrobial-coated devices had a significantly lower
rate of colonization than the uncoated devices (five of thirteen compared with
twelve of twelve, p = 0.0016) and were associated with significantly lower
rates of osteomyelitis (six of thirteen compared with twelve of twelve, p =
0.005) and device-related osteomyelitis (five of thirteen compared with twelve
of twelve, p = 0.0016). Bacteremia did not develop in any rabbit.
Conclusions: Orthopaedic devices coated with minocycline and
rifampin significantly protected against device colonization and infection due
to Staphylococcus aureus in this in vivo rabbit model.
Clinical Relevance: It is possible that orthopaedic devices coated
with this unique combination of antimicrobial agents may protect against the
development of clinical infection in humans.