Vancomycin use and monitoring in adult patients with chronic osteomyelitis of the long bones

Background: Vancomycin is the treatment of choice for oxacillin-resistant Staphylococcus aureus (ORSA) infections in long bones. However, an inappropriate dosage of vancomycin may result in toxicity or treatment failure. Materials and methods: In this study, 21 patients infected with ORSA were treated with intravenous vancomycin. The concentration of serum vancomycin was measured by fluorescence polarization immunoassay. The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were also measured at each blood sampling. Results: When vancomycin doses were given based on the manufacturer's recommendations, 46% (39/84) of the patients were found to have inappropriate blood levels. After the dose of vancomycin was then adjusted, at the third blood sampling, a higher percentage of adequate peak and trough serum vancomycin concentrations were found. There was no statistical difference in peak or trough levels produced by intravenous doses of vancomycin of 500 mg given every 6 h or 1,000 mg given every 12 h. However, initial dosing of 1,000 mg every 12 h may be a better choice than 500 mg every 6 h for younger patients. The CRP was significantly decreased (P < 0.01) at the time of the second blood sampling during vancomycin treatment. Conclusions: The data from this study suggest that peak and trough vancomycin concentrations should be monitored for patients who have chronic osteomyelitis and prolonged vancomycin treatment. Further studies may help resolve whether such monitoring beneficially affects outcomes and health care costs.