Combined local and systemic antibiotic treatment is effective against experimental Staphylococcus aureus peri‐implant biofilm infection

We hypothesized that systemic ceftriaxone and high concentration local antibiotics might eradicate peri‐implant sepsis. Experiment 1: Eighty‐four implants inoculated with biofilm‐forming Staphylococcus aureus were treated in vitro with gentamicin, vancomycin, gentamicin + rifampin, or vancomycin + rifampin for 2, 4, or 8 days. Experiment 2: Forty‐five implants were wired in vivo to rat femurs and inoculated with 1 × 10⁶ CFU S. aureus. After 48 h, rats were treated once daily for 5 days with systemic ceftriaxone, local tobramycin or ceftriaxone, and tobramycin. Experiment 3: Forty implants with established S. aureus biofilms were wired in vivo to rat femurs. After 48 h, rats were treated with systemic ceftriaxone alone or in combination with local gentamicin, gentamicin and rifampin, or vancomycin. Experiment 1: 100% of implants treated in vitro with gentamicin were sterile after 48 h. The other treatments did not become sterile until 4 days. Experiment 2: No implant was culture negative. The combination of systemic ceftriaxone and local tobramycin was significantly better than others (p < 0.008). Experiment 3: Systemic ceftriaxone alone was ineffective. All implants treated with systemic ceftriaxone and local gentamicin were sterile (p < 0.001), the other groups were less effective. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1320–1326, 2015.