In vitro Antimicrobial Activity Comparison of Linezolid, Tedizolid, Sutezolid and Delpazolid Against Slowly Growing Mycobacteria Isolated in Beijing, China.

Background: The antimicrobial activities of some new oxazolidinones against slowly growing mycobacteria (SGM) have never been well evaluated.

Methods: We evaluate the in vitro susceptibility of 20 reference strains and 157 clinical isolates, pertaining different SGM species, against four oxazolidinones, ie, delpazolid, sutezolid, tedizolid and linezolid. In addition, the association of linezolid resistance and mutations in 23srRNA, were also tested.

Results: Sutezolid presented the strongest antimicrobial activity against the clinical isolates of than the other oxazolidinones, with MIC at 2 μg/mL and MIC at 4 μg/mL. MICs of sutezolid were usually 4- to 8-fold lower than these of linezolid against and . The tested isolates of were susceptible to all of the four oxazolidinones. According to the multiple sequence alignment, novel mutations (A2267C and A2266G) in and mutations (Thr147Ala) in were identified in this study which have plausible involvement in rendering resistance against linezolid.

Conclusion: This study showed that sutezolid harbors the strongest inhibitory activity against and in vitro, which provided important insights on the potential clinical application of oxazolidinones for treating SGM infections.