In Vitro activities of Tedizolid and comparator antimicrobial agents against clinical isolates of Staphylococcus aureus collected in 12 countries from 2014 to 2016

Clinical isolates of Staphylococcus aureus (n = 3929) collected by 54 medical center laboratories in 12 countries in 2014-2016 were tested for in vitro susceptibility to tedizolid, linezolid, and 11 comparators using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodology with minimum inhibitory concentrations (MICs) interpreted by CLSI M100-S26 (2016) criteria. All isolates of S. aureus tested were susceptible to both tedizolid (MIC, ≤0.5 μg/mL) and linezolid (MIC, ≤4 μg/mL). The concentration of tedizolid that inhibited 90% of isolates (MIC90) was 0.5 μg/mL, 4-fold lower than linezolid (MIC90, 2 μg/mL). Tedizolid MIC frequency distributions were equivalent for methicillin-susceptible (MSSA; n = 2090; MIC90, 0.25 μg/mL) and methicillin-resistant (MRSA; n = 1839; MIC90, 0.25 μg/mL) S. aureus. We conclude that tedizolid possesses more potent in vitro activity than linezolid against recently collected isolates of S. aureus, including isolates of MRSA, and that resistance to currently marketed oxazolidinones (tedizolid and linezolid) remains very uncommon.