Efficacy of linezolid versus vancomycin in the treatment of methicillin-resistant Staphylococcus aureus discitis: a controlled animal model.

Study Design: A rabbit model was used to assess the efficacy of linezolid and vancomycin for the treatment of discitis due to methicillin-resistant Staphylococcus aureus (MRSA). Nontreated controls were used for comparison.

Objective: The purpose of this study was to determine if there was a therapeutic difference between using linezolid and vancomycin in the treatment of MRSA discitis.

Summary Of Background Data: Vancomycin is currently the gold standard treatment for medical management of MRSA discitis. Linezolid is a relatively new drug that has been approved for treatment of MRSA infections, but currently there is no research demonstrating its efficacy at treating infections of the disc space.

Methods: Twenty-four rabbits were inoculated with MRSA at two adjacent lumbar disc spaces via an anterior retroperitoneal approach. Six rabbits were to receive only pain medication and to serve as controls. Ten rabbits were assigned to a 5-day course of intravenous vancomycin, and 8 were assigned to a 5-day course of intravenous linezolid. Disc spaces were sent for quantitative culture after the 5-day treatment course.

Results: The mean culture growth for the disc spaces was not statistically different between the linezolid treated group and the nontreated controls. While vancomycin treatment did lead to lower bacterial loads when compared with controls, the reduction was not statistically significant. When bacterial counts for the vancomycin group and linezolid group were compared, vancomycin treatment resulted in less bacterial growth. This difference was statistically significant.

Conclusions: Linezolid is a clinically attractive alternative to vancomycin due to its mild side effect profile and oral bioavailability. However, in this MRSA discitis model with a short treatment course, vancomycin was superior to linezolid.