MIC and zone distributions and ECOFFs

MIC and zone diameter distributions and ECOFFs

1. Distributions and ECOFFs 

2. MIC and zone diameter correlations


The EUCAST software, originally created in 2003, for displaying distributions of MIC-values (generated with methods calibrated to broth microdilution or agar dilution) and inhibition zone diameters (generated with EUCAST disk diffusion methodology) was re-programmed during 2020 and re-launched on 24 November, 2020. Each graph is shown in two versions where one is constructed by adding all approved distributions and the other by adding weighted distributions. The later is generated through converting numbers to per cent before adding individual distributions. This prevents large distributions from dominating or even "obliterating" smaller distributions and allows all distributions equal weight. During 2021 distributions are curated in accordance with EUCAST SOP10.1 and all values gradually reviewed.


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).


Access to MIC and zone diameter distribution data.
For researchers interested in using the detailed individual distributions for projects, the database curators may decide to provide that data upon written (email) request. Requests should outline the purpose to which the data will be applied, and based on that information, curators or owners of data may demand to be listed as authors in any publications arising from the research.


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 currently being critically evaluated.
Official ECOFFs are determined by EUCAST, adhering to protocols generated by the "EUCAST Subcommittee on MIC distributions and the determination of ECOFFs" (SOP10.2).


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

Submit MIC distributions to Gunnar Kahlmeter or Erika Matuschek.


For Copyright issues, go to the EUCAST home page.






























Instructions and templates for webmaster

1. Instructions 

2. Template for import of MICs and ECOFF stats 

3. Template for import of zones and ECOFF stats 

4. Import of new MIC-data

5. Import of new zone data