Staphylococcus aureus may invade and persist intracellularly in prosthetic joint infections (PJIs). Despite optimized treatments with levofloxacin plus rifampin, the intracellular reservoir may lead to infection relapse. This study assessed the intracellular activity of levofloxacin and rifampin in an in-vitro model of human osteoblastic infection.
Ten meticillin-susceptible S. aureus strains were used to infect osteoblastic MG63 cells. Osteoblasts were challenged with rifampin and levofloxacin at cortical and cancellous bone concentrations. Efficacy was measured as the intracellular counts of colony-forming units (log
All regimes led to a significant decrease in CFU count compared with controls (1-2 log
Levofloxacin plus rifampin had good intracellular activity against S. aureus. However, from the intracellular perspective, the addition of rifampin to levofloxacin showed no benefit but could account for an increased number of SCVs.