Linezolid versus vancomycin for the treatment of infections caused by methicillin-resistant Staphylococcus aureus in Japan

Objectives: To compare the efficacy and safety of linezolid and vancomycin for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in Japan. Methods: Patients with nosocomial pneumonia, complicated skin and soft-tissue infections or sepsis caused by MRSA were randomized to receive linezolid (600 mg every 12 h) or vancomycin (1 g every 12 h). Results: One hundred patients received linezolid and 51 received vancomycin with outcomes evaluated at the end of therapy (EOT) and at the follow-up (FU), 7-14 days later. At EOT, clinical success rates in the MRSA microbiologically evaluable population were 62.9% and 50.0% for the linezolid and vancomycin groups, respectively; and microbiological eradication rates were 79.0% and 30.0% in the two groups, respectively (P < 0.0001). At FU, the clinical success rates were 36.7% for both groups and the microbiological eradication rates were 46.8% and 36.7%, respectively. Reversible anaemia (13%) and thrombocytopenia (19%) were reported more frequently in linezolid patients; laboratory analysis showed mild decrease in platelet counts with full recovery by FU. The mean platelet count in linezolid patients with thrombocytopenia was 101 000/mm(3). Significantly low platelet counts (<50 000/mm(3)) were observed more frequently in patients receiving vancomycin than in linezolid patients (6% versus 3%). Mean changes in haemoglobin levels between the two groups were not different. Conclusions: Linezolid is as effective as vancomycin for the treatment of MRSA infections and may be more effective than vancomycin in achieving microbiological eradication. Haematological adverse events were reported more frequently in linezolid-treated patients; analysis of laboratory data showed a mild reversible trend towards lower platelet counts.