Update on LinezolidIn VitroActivity through the Zyvox Annual Appraisal of Potency and Spectrum Program, 2013

Abstract

ABSTRACTLinezolid showed MIC50s and MIC90s of 1 μg/ml (for both) againstStaphylococcus aureus. TwoS. aureusstrains exhibited higher MICs (4 to 8 μg/ml) caused bycfrand/or target site mutations, including the first detection ofcfrin Poland. Linezolid (MIC50and MIC90, 0.5 and 1 μg/ml) had potent MICs against coagulase-negative staphylococci (CoNS). Four CoNS had MICs of 16 to 128 μg/ml due to alterations in 23S rRNA and/or L3/L4. Linezolid inhibited all enterococci and streptococci at ≤2 μg/ml, except for oneEnterococcus faeciumstrain (MIC, 8 μg/ml; G2576T [Escherichia colinumbering] mutation).