22.07.2025

How to make use of EUCAST MIC and zone distributions

EUCAST distributions of MIC and Zone diameters (https:/mic.eucast.org; choose either “MIC” or “Disk diffusion”) are freely available. When sufficiently many acceptable distributions were available to the curators, ECOFFs were determined and listed beneath each graph together with confidence intervals. When users have performed 50 – 100 phenotypic tests (MIC determinations or disk diffusion), create your own distribution and check this against the EUCAST reference distribution. If the wild type part of the distribution is superimposable on the EUCAST counterpart, this validates methodology in the individual laboratory and the use of EUCAST breakpoints. If not, trouble shoot and discuss with your National AST Committee (https://www.eucast.org/nac), or contact EUCAST.