Prosthesis joint infections: contributions of experimental models to understanding the limitations of antibiotic efficacy and optimization of medical treatment.

Post-operative infection remains the main complication of prosthetic joint replacement, since its inception by Robert and Jean Judet in 1947. Because the number ofjoint prostheses implanted annually is increasing substantially, these infections are becoming more-and- more common and optimizing their management is an important issue for medical and economic reasons. Prosthetic joint infections are a good model for understanding the limitations of in vivo antibiotic eficacy. Antibiotic therapy faces a duel challenge: (i) the difficulty of eradicating the bacteria in contact with a prosthesis, partly due to the metabolic state of the bacteria enclosed within the biofilm ; (ii) the poor difusion of antibiotics into the infected cortical bone, as revealed autoradiographically in an experimental model of prosthetic joint infection due to staphylococcus, the main bacterium responsible for these infections. The " natural " emergence of antibiotic-resistant bacteria, even though they have not been subject to antibiotic-selection pressure, was observed more recently in the same model. The optimal management of these infections requires medico-surgical treat- ment using, whenever possible, antibiotics like rifampin combined with another antimicro- bial, whose remarkable efficacy was demonstrated in experimental models of staphylococ- cal infections.