Objectives: Staphylococcus aureus is the most common pathogen isolated in osteomyelitis. This study evaluated the efficacies of telavancin (an investigational, rapidly bactericidal lipoglycopeptide with a multifunctional mechanism of action against Gram-positive bacteria), vancomycin and linezolid in a rabbit methicillin-resistant S. aureus (MRSA) osteomyelitis model.
Methods: Localized osteomyelitis was induced in New Zealand White rabbits by percutaneous injection of 10(6) cfu of MRSA clinical isolate 168-1 into the intramedullary cavity. Two weeks post-infection, rabbits with radiographically confirmed, localized proximal tibial osteomyelitis were randomized into four groups (n = 15 per group): untreated controls; vancomycin 30 mg/kg subcutaneously every 12 h; linezolid 60 mg/kg orally every 8 h; and telavancin 30 mg/kg subcutaneously every 12 h. After 4 weeks of antibiotic treatment, animals were left untreated for 2 weeks. Rabbits were then euthanized and the tibias harvested. Bone matrix and marrow from each tibia were cultured and bacterial counts determined.
Results: For MRSA isolate 168-1, the MIC was 0.25 mg/L for telavancin, 0.5 mg/L for vancomycin and 0.5 mg/L for linezolid. Tibial cultures were positive for MRSA in 9 of 15 (60%) untreated controls, and 3 of 15 (20%) telavancin-treated, 3 of 15 (20%) vancomycin-treated and 4 of 14 (29%) linezolid-treated rabbits.
Conclusions: Telavancin has comparable efficacy to vancomycin and linezolid in a rabbit model of MRSA osteomyelitis.