Combination of quinupristin-dalfopristin (Synercid) and rifampin is highly synergistic in experimental Staphylococcus aureus joint prosthesis infection

Abstract

We compared the efficacies of quinupristin-dalfopristin (Q-D; 30 mg/kg of body weight every 8 h) and vancomycin (60 mg/kg twice daily), alone or in combination with rifampin (10 mg/kg twice daily), in a rabbit model of methicillin-resistant Staphylococcus aureus knee prosthesis infection. In contrast to vancomycin, Q-D significantly reduced the mean log(10) CFU per gram of bone versus that for the controls. The combination of rifampin with either Q-D or vancomycin was significantly more effective than monotherapy.

FIG. 1.

In vitro killing curves for methicillin-resistant S. aureus strain HM 1054, using different antibacterial agents and combinations, all at five times the MIC. □, control; ◊, Q-D; ○, vancomycin; ▴, rifampin; ⧫, Q-D plus rifampin; •, vancomycin plus rifampin.