Comparative in vitro potency and kill curve activity of tedizolid and linezolid against Gram-positive bacteria isolated from Chinese hospitalized patients in 2013-2016.

We compared the kill-curve activity of tedizolid and linezolid at clinically relevant (total or free plasma, lung) concentrations against methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae (PRSP) isolated from Chinese patients. Tedizolid had greater in vitro potency than linezolid against staphylococci, streptococci and enterococci species (tedizolid minimum inhibitory concentration (MIC) range: <= 0.016-0.5 mu g/mL; linezolid MIC range: 0.25-2 mu g/mL). In kill-curve experiments, growth of MRSA was inhibited at tedizolid concentration of 0.6 mu g/mL (i.e. 4.8 x MIC; MIC = 0.125 mu g/mL) and linezolid concentration of 2 mu g/mL (2x MIC; MIC = 1 mu g/mL). Against PRSP, tedizolid at a concentration of 0.25 mu g/mL (representing its MIC) was bacteriostatic, but exerted a bactericidal effect at higher concentrations. Results were similar for linezolid, however, even at 21 mu g/mL, a small proportion of organisms survived beyond 24 h. The results demonstrated the potency of tedizolid against clinical strains of Gram-positive pathogens supporting its use as a suitable alternative to linezolid in Chinese patients.