- Volume 65, Issue 10, 2016

To evaluate the in vitro antimicrobial activities of tedizolid, linezolid and other comparators against clinically significant Gram-positive cocci isolates from hospital-acquired pneumonia (HAP), skin and soft tissue infection (SSTI) and bloodstream infection (BSI), 2140 nonduplicate isolates (23.7 % isolated from HAP, 46.8 % from SSTI and 29.5 % from BSI) were consecutively collected in 26 hospitals in 17 cities across China during 2014. These pathogens included 632 methicillin-resistant Staphylococcus aureus, 867 methicillin-sensitive Staphylococcus aureus, 299 coagulase-negative Staphylococcus (CoNS), 104 Enterococcus faecalis, 99 Enterococcus faecium, 13 Streptococcus pneumoniae, 23 α-haemolytic Streptococcus and 103 β-haemolytic Streptococcus. MICs of routine clinical antibiotics were determined by broth microdilution method according to the Clinical and Laboratory Standards Institute guidelines 2015. Tedizolid, linezolid, vancomycin, daptomycin, teicoplanin and tigecycline showed high in vitro activity against Gram-positive pathogens (≥98.0 % susceptible), and tedizolid exhibited four- to eight fold greater activity than linezolid against the pathogens tested, with MIC90s of methicillin-resistant Staphylococcus aureus, α-haemolytic Streptococcus and β-haemolytic Streptococcus (0.25 vs 2 µg ml−1); methicillin-sensitive Staphylococcu s aureus, E. faecalis and E. faecium (0.5 vs 2 µg ml−1); methicillin-resistant CoNS and methicillin-sensitive CoNS (0.25 vs 1 µg ml−1); and Streptococcus pneumoniae (0.125 vs 0.5 µg ml−1). Tedizolid MIC90s associated with different infections did not show significant differences, and the drug exhibited excellent activity against surveyed Gram-positive pathogens associated with HAP, SSTI and BSI, including linezolid-nonsusceptible strains. These data suggest that tedizolid could be an alternative to linezolid for the treatment of infections caused by Gram-positive organisms.