EUCAST clinical breakpoints-bacteria (v 12.0)15 was used for the interpretation of colistin and polymyxin B MIC results (susceptible, ≤ 2 mg/L; resistant, > 2 mg/L). BMD results were considered the reference standard. Essential agreement (EA) was defined as the percentage of MICs within a single doubling dilution of the corresponding reference MICs. Categorical agreement (CA) was the proportion of isolates classified in the same susceptibility category by BMD and the compared methods. Very major error (VME) was defined as false susceptible results compared to BMD. VME rates were calculated using the number of resistant isolates reported by BMD as the denominator. Major error (ME) was defined as false resistant results compared to BMD. ME rates were calculated using the number of susceptible isolates by BMD as the denominator. According to CLSI recommendations, a new system can be acceptable when it meets the standards as follows: CA > 90%, EA > 90%, VME < 1.5%, and ME < 3%.16