In Vitro Activities of Linezolid and Tigecycline Against Methicillin-Resistant Staphylococcus aureus Strains

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is a nosocomial pathogen that causes morbidity and mortality worldwide. The options for the treatment of MRSA infections are limited. Linezolid is an antibacterial agent of oxazolidinone group. It has a spectrum limited to gram-positive bacteria. Tigecycline is a broad-spectrum antibiotic of glycylcycline group. A total of 60 MRSA strains isolated from various clinical specimens were included in the study. Minimum inhibitory concentrations (MICs) were determined by Etest method, according to the Clinical and Laboratory Standards Institute (CLSI) and Food and Drug Administration (FDA) criteria. The MIC(90) was 1 microg/ml for linezolid (range 0.094-4 microg/ml), and 0.38 microg/ml for tigecycline (range 0.032-1 microg/ml). All strains were found to be susceptible to linezolid, and only one strain's MIC value was above the threshold for tigecycline. Tigecycline and linezolid may represent therapeutic options for infections caused by MRSA.