[In vitro activity of linezolid against clinical isolates of methicillin-resistant Staphylococcus aureus].

In recent years, there has been a dramatic increase in the number of infections caused by multidrug-resistant Gram-positive microorganisms, making necessary the search for alternative antibacterial agents. Linezolid is a new synthetic antimicrobial agent with activity against multidrug-resistant Gram-positive cocci. The objective of this study was to determine the in vitro activity of linezolid against 74 clinical isolates of methicillin-resistant Staphylococcus aureus. Minimal inhibitory concentrations were determined by an agar dilution method following NCCLS criteria. Vancomycin, teicoplanin, rifampicin, trimethoprim-sulfamethoxazole and linezolid were studied at concentrations ranging from 128 to 0.008 mg/l. All of the isolates were susceptible to vancomycin, teicoplanin, and linezolid while four strains (5.4%) were resistant to rifampicin and five (6.7%) to trimethoprim-sulfamethoxazole. Linezolid showed excellent in vitro activity against 74 clinical isolates of methicillin-resistant Staphylococcus aureus with an MIC ranging from 0.25 to 2 mg/l