MIC and zone distributions and ECOFFs

MIC and zone diameter distributions and ECOFFs

Link to MIC and zone diameter distributions and ECOFFs.

The website gives MIC distributions (and since 2010 inhibition zone diameter distributions generated with the EUCAST disk diffusion method) for a wide range of organisms and antimicrobial agents, including antifungals.

The distributions are based on collated data from a total of more than 30 000 MIC distributions containing more than several million MICs from worldwide sources.  The distributions include MICs from national and international studies such as resistance surveillance programs and and MIC distributions from published articles, the pharmaceutical industry drug development programmes, veterinary programmes and from individual laboratories. Histograms display wild type organisms, together with EUCAST epidemiological cut-off values (ECOFFs) and tentative ECOFFs (TECOFF).


The distributions should never be referred to in any epidemiological context since data from many time periods and many countries have been aggregated.


Using agreed criteria for the acceptance of MIC distributions, the database and ECOFFs are being critically evaluated during 2018 and 2019.  Official ECOFFs are determined by EUCAST, adhering to protocols generated by the "EUCAST Subcommittee on MIC distributions and the determination of ECOFFs" (SOP10 and the document "Considerations in the numerical estimation of ECOFF values" - which will be integrated in SOP10). 


The 2020 updated version of the ECOFFinder program is available from the EUCAST website. This is a tool made available by EUCAST Scientific Secretary John Turnidge for people wanting to assess MIC distribution data. Caveats for use of the program has been added 2020 (see first page of Excel file).


Questions and comments on EUCAST wild type distributions and ECOFFs. 

Contributions of MIC and Zone diameter distributions can be made using the following Excel file templates: 


The following agents and/or species were recently evaluated and ECOFFs revised or confirmed:  

Note that the presence or absence of a resistance mechanism (MRSA vs. MSSA, betalactam with or without an inhibitor) does not alter the ECOFF which is always decided by the phenotypic expression. Neither does the addition of an inhibitor (unless this has activity of its own) - the ECOFF always pertain to the active substance.

Changes to ECOFFs.


The curators of the database are currently Gunnar Kahlmeter, Erika Matuschek, Jenny Åhman, Derek Brown and John Turnidge.

Submit MIC distributions to Gunnar Kahlmeter or Erika Matuschek.


For Copyright issues, go to the EUCAST home page.