Methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci: emerging problems and new prospects for management.

INTRODUCTION Infections due to multidrug-resistant Gram-positive bacteria are a growing worldwide problem, particularly among seriously ill patients. A number of studies have demonstrated that patients infected with either methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) are at higher risk for mortality and medical resource expenditures. METHODS A non-systematic evidence-based review of linezolid, the first commercially available oxazolidinone, and quinupristin/dalfopristin, the first injectable streptogramin, for management of these multidrug-resistant infections was conducted. RESULTS As infections due to VRE increase and vancomycin-insensitive MRSA emerge, vancomycin is becoming less effective for managing Gram-positive infections. Preclinical comparative studies demonstrated that linezolid and quinupristin/dalfopristin are highly effective in eradicating both susceptible and resistant staphylococci, streptococci, and enterococci. Clinical experience, including phase III and compassionate-use data, with these newer agents in the treatment of MRSA and VRE infections are discussed. CONCLUSIONS The clinical experiences thus far with linezolid and quinupristin/dalfopristin for MRSA and VRE infections have demonstrated efficacy, making these agents important additions to the limited number of therapeutic alternatives for Gram-positive infections.