Multicenter Clinical Evaluation of ETEST Plazomicin (PLZ) for Susceptibility Testing of Enterobacterales

J Clin Microbiol. 2022 Jan 19;60(1):e0183121. doi: 10.1128/JCM.01831-21. Epub 2021 Nov 10.


Plazomicin (PLZ), brand name ZEMDRI (Cipla Therapeutics), is a novel aminoglycoside antibiotic approved by the U.S. Food and Drug Administration (FDA) for treatment of complicated urinary tract infections including pyelonephritis. ETEST® is a gradient diffusion method that represents an alternative to the more laborious broth micro-dilution (BMD) method for performing antimicrobial susceptibility testing (AST). A multi-center evaluation of the performance of the new ETEST PLZ (bioMérieux) was conducted in comparison with BMD following FDA and International Standards Organization (ISO) recommendations using FDA-defined breakpoints. Clinical isolates of Enterobacterales (n = 598) were included. Fifty-three isolates were resistant to PLZ according to BMD. Overall, the ETEST PLZ demonstrated 99.0% essential agreement (EA), 92.8% category agreement (CA), 1.9% very major errors (VME), 0% major errors (ME), and 7.0% minor errors (mE) with both clinical and challenge isolates of Enterobacterales. The VME was found for a single Serratia marcescens strain. Individual species demonstrated EA rates ≥ 90%. In conclusion, we report that ETEST PLZ represents an accurate tool for performing PLZ AST of Enterobacterales.

Keywords: ETEST; Enterobacterales; Plazomicin; antimicrobial susceptibility testing; gradient methods; plazomicin resistance mechanisms.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Disk Diffusion Antimicrobial Tests / methods
  • Enterobacteriaceae*
  • Humans
  • Microbial Sensitivity Tests
  • Pseudomonas aeruginosa*
  • Sisomicin / analogs & derivatives


  • Anti-Bacterial Agents
  • plazomicin
  • Sisomicin