Evaluation of tedizolid against Staphylococcus aureus and enterococci with reduced susceptibility to vancomycin, daptomycin or linezolid

J Antimicrob Chemother. 2016 Jan;71(1):152-5. doi: 10.1093/jac/dkv302. Epub 2015 Oct 16.


Objectives: Tedizolid displays potent activity against Gram-positive pathogens. In vitro studies against clinical isolates of Staphylococcus aureus and enterococci demonstrated improved tedizolid activity over linezolid. However, this is not well-characterized against a large collection of resistant isolates, including vancomycin-intermediate S. aureus (VISA), heterogeneous VISA (hVISA), daptomycin-non-susceptible (DNS) S. aureus, linezolid-resistant (LR) S. aureus and VRE. Therefore, our objective was to determine tedizolid activity versus other agents, against MRSA and VRE with various resistance phenotypes.

Methods: In total, 302 MRSA (75 DNS, 100 VISA, 120 hVISA and 7 LR) and 220 VRE [100 Enterococcus faecalis (all susceptible to daptomycin and linezolid) and 120 E. faecium (25 DNS and 10 LR)] were evaluated. LR isolates were analysed for the cfr gene. MICs of tedizolid, linezolid, ampicillin, clindamycin, daptomycin, gentamicin, levofloxacin, oxacillin, tigecycline, trimethoprim/sulfamethoxazole and vancomycin were determined in accordance with CLSI guidelines.

Results: Tedizolid MIC90 values for hVISA, VISA and DNS were 0.5 mg/L (versus 4, 4 and 2 mg/L, respectively, for linezolid). The tedizolid MIC range for LR MRSA was 0.063-1 mg/L. Two LR MRSA possessed the cfr gene with tedizolid MICs of 0.125 and 0.25 mg/L (linezolid MICs of 16 and 8 mg/L). The tedizolid MIC90 for vancomycin-resistant E. faecalis and E. faecium was 0.25 and 1 mg/L, respectively; three dilutions lower for E. faecalis and two dilutions lower for E. faecium compared with linezolid.

Conclusions: Tedizolid MICs demonstrate activity against isolates with decreased susceptibility to alternative agents, including linezolid. Tedizolid may be a viable treatment option in clinical situations with MDR Gram-positive pathogens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Daptomycin / pharmacology
  • Drug Resistance, Bacterial*
  • Enterococcus / drug effects*
  • Enterococcus faecalis / drug effects*
  • Enterococcus faecalis / isolation & purification
  • Enterococcus faecium / drug effects*
  • Enterococcus faecium / isolation & purification
  • Gram-Positive Bacterial Infections / microbiology
  • Humans
  • Linezolid / pharmacology
  • Microbial Sensitivity Tests
  • Organophosphates / pharmacology*
  • Oxazoles / pharmacology*
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / isolation & purification
  • Vancomycin / pharmacology


  • Anti-Bacterial Agents
  • Organophosphates
  • Oxazoles
  • Vancomycin
  • Linezolid
  • Daptomycin
  • tedizolid phosphate