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Treatment of experimental chronic osteomyelitis due to staphylococcus aureus with vancomycin and rifampin
Abstract:
Vancomycin was used alone and in combination with rifampin in the treatment of experimental osteomyelitis due to Staphylococcus aureus in rabbits. Treatment with 60 mg of vancomycin/kg of body weight twice a day for 28 days was ineffective in sterilizing infected rabbit bones. Rifampin (40 mg/kg) injected once a day for 28 days sterilized 57% of infected rabbit bones. Treatment with a combination of vancomycin and rifampin for either 14 or 28 days was significantly more effective than either drug used alone, sterilizing 84% and 90%, respectively, of the infected bones of treated animals. A possible explanation for the failure of vancomycin when used alone may be that its in vitro activity against the infecting strain of S. aureus (as measured by minimal inhibitory concentrations or minimal bactericidal concentrations) was substantially less under anaerobic conditions (that is, at partial pressures of oxygen analogous to those in osteomyelitic bones) than under aerobic conditions.
Insights
Vancomycin combined with rifampin effectively treated experimental Staphylococcus aureus osteomyelitis in rabbits, outperforming either antibiotic alone. This combination therapy offers a promising approach for bone infection treatment.
Area of Science:
- Infectious Diseases
- Pharmacology
- Surgical Innovation
Background:
- Osteomyelitis, a bone infection often caused by Staphylococcus aureus, presents significant treatment challenges.
- Vancomycin monotherapy has shown limited efficacy in experimental models, potentially due to reduced activity under anaerobic conditions found in bone infections.
Purpose of the Study:
- To evaluate the efficacy of vancomycin alone and in combination with rifampin for treating experimental Staphylococcus aureus osteomyelitis in rabbits.
- To investigate the impact of anaerobic conditions on vancomycin's in vitro activity against Staphylococcus aureus.
Main Methods:
- Rabbits with experimental Staphylococcus aureus osteomyelitis were treated with vancomycin (60 mg/kg twice daily) or rifampin (40 mg/kg once daily) for 28 days.
- Combination therapy with vancomycin and rifampin was administered for 14 or 28 days.
- Bone sterilization rates were assessed for each treatment group.
Main Results:
- Vancomycin alone was ineffective in sterilizing infected rabbit bones.
- Rifampin monotherapy sterilized 57% of infected bones after 28 days.
- Combination therapy achieved significantly higher sterilization rates: 84% after 14 days and 90% after 28 days.
Conclusions:
- Combination therapy of vancomycin and rifampin is significantly more effective than either agent alone in treating experimental Staphylococcus aureus osteomyelitis.
- The reduced in vitro activity of vancomycin under anaerobic conditions may explain its limited efficacy as a single agent in osteomyelitis treatment.