[Role of antibiotics in the treatment of infected joint prosthesis]

Infection is a rare, but extremely severe, complication of prosthetic joint surgery. Until recently, antimicrobial agents were not generally used in the management of such infections. Antibiotics now have an important role, either combined with replacement surgery or even as the only treatment in selected cases. In earlier studies, high failure rates were reported with conservative therapy. These unsatisfactory results were probably due to a lack of collaboration between surgeons, infectious disease specialists and microbiologists. All patients with a long history of infection or with loosened implants should undergo joint replacement. Early or rapidly diagnosed hematogenous infection in patients with stable prostheses can be treated conservatively. In most cases, such a treatment is preceded by revision surgery, which is needed for microbiological diagnosis and for debridement. The choice of antibiotics depends on the microorganism involved and the results of susceptibility testing. The most important etiologic agents are Staphylococcus aureus and coagulase-negative staphylococci. Antimicrobial drugs used in device-related infections should act on surface-adherent and stationary-phase bacteria. In an animal model, rifampin combined with a quinolone has proved to have the highest cure rate against staphylococcal foreign-body infection. Rifampin is indeed highly efficacious on surface-adherent and stationary-phase bacteria. These experimental data were confirmed in clinical studies; cure rates of 60-80% were observed with rifampin combinations without joint replacement. Antimicrobial therapy should be continued over at least 3 months in hip implant infection and at least 6 months in knee implant infection. Before treatment is stopped, signs and symptoms of infection must have been absent with C-reactive protein normal for at least 1 month.