In vitro activity of linezolid and 11 other antimicrobials against 566 clinical isolates and comparison between NCCLS microdilution and Etest methods

The in vitro activity of linezolid and 11 other antimicrobials was determin ed for 566 clinical isolates of Staphylococcus aureus, Staphylococcus epide rmidis, Enterococcus spp,, Streptococcus pyogenes, Streptococcus agalactiae , Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhali s, some of them resistant to several antibiotics, using a broth microdiluti on method and the Etest method. All Gram-positive organisms tested were inh ibited by a concentration of less than or equal to4 mg/L of linezolid, incl uding methicillin-resistant staphylococci, vancomycin- and ampicillin-resis tant enterococci, and penicillin-intermediate and -resistant pneumococci. M ICs of linezolid by the Etest method were usually one to two dilution value s lower than those obtained by microdilution.