Evaluation of the Colistin HiMIC Plate Kit for Colistin Susceptibility Testing of Klebsiella pneumoniae

Colistin HiMIC Plate Kit (HiMedia Laboratories), a new commercial broth microdilution (BMD) test for colistin susceptibility testing was evaluated. BMD according to ISO standard 20776-1 (2019) with two-fold dilutions from 128 to 0.125 mg/L was used as a reference method. The colistin reference MICs (minimal inhibitory concentration) ranged from 0,25 to 128 mg/L with 15 (20.5%; 15/73) isolates having colistin reference MICs close to the current EUCAST breakpoint (MICs of 2, 4, and 8 mg/L). The study assessed the compliance of a commercial kit with the CLSI criteria, including categorical agreement (CA) and essential agreement (EA ≥90%), very major error (VME rate) <3%, and major error (ME) rate <3%. On 73 carbapenemase-producing