Multicenter Clinical Evaluation Of ETEST® Plazomicin (PLZ) For Susceptibility Testing Of Enterobacterales.

Plazomicin (PLZ), brand name ZEMDRI (Cipla Therapeutics), is a novel aminoglycoside antibiotic approved by the US 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.