Abstract

ABSTRACT: Background: The aim of this study was to compare the antibacterial efficacy of vancomycin and linezolid in a rabbit model of methicillin-resistant Staphylococcus aureus (MRSA) meningitis. Material/Methods: Meningitis was induced by intracisternal inoculation of ATCC 43300 strain. After 16 h incubation time and development of meningitis, the vancomycin group received vancomycin 20 mg/kg every 12 h. The linezolid-10 and linezolid-20 groups received linezolid in 10 and 20 mg/kg dosages every 12 h, respectively. The control group did not receive any antibiotics. Cerebrospinal fluid bacterial counts were measured at the end of 16-h incubation time and at the end of 24-h treatment. Results: Bacterial counts were similar in all groups at 16 h. At the end of treatment the decrease in bacterial counts in the vancomycin group was approximately 2 logs higher than the linezolid-20 group (p>0.05) and approximately 4 logs higher than in the linezolid-10 group (p: 0.037) (Vancomycin group: –2.860±4.495 versus Linezolid-20: –0.724±4.360, versus Linezolid-10: 1.39±3.37). Full or partial bacteriological response was higher in vancomycin versus linezolid-10 (p: 0.01), but not vancomycin versus linezolid-20 or linezolid-10 versus-linezolid-20 groups. Conclusions: Our results suggest that linezolid is not statistically inferior to vancomycin in the treatment of MRSA meningitis in an experimental rabbit model in 20 mg/kg q12 h dosage; however, it is inferior in 10 mg/kg q12 h dosage. Additional data should gathered to confirm these findings in advance of clinical trials to assess efficacy in humans.

Keywords: Oxazolidinones - therapeutic use, Methicillin-Resistant Staphylococcus aureus - growth & development, Meningitis, Bacterial - microbiology, Colony Count, Microbial, Anti-Bacterial Agents - therapeutic use, Acetamides - therapeutic use, Rabbits, Staphylococcal Infections - microbiology, Vancomycin - therapeutic use