MIC and zone diameter distributions and ECOFFs

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The EUCAST software, originally created in 2003, for displaying distributions of MIC-values (generated with methods calibrated to reference broth microdilution or for some agents and species, agar dilution) and inhibition zone diameters (generated with EUCAST standardised 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 just aggregating all approved distributions, and the other by giving each distribution equal weight before constructing the aggregate. The later is generated through converting numbers to per cent before aggregation. This prevents large distributions from dominating or even "obliterating" smaller distributions and allows all distributions equal weight. During 2021-2022 distributions are curated in accordance with EUCAST SOP10.2 and all distributions and ECOFF values gradually reviewed.

For disk diffusion zone diameter distributions, a dedicated software for the calculation of zone diameter ECOFFs was created and applied in 2023.

The distributions are based on collated data from a total of more than 40 000 distributions containing more than several million MIC values and zone diameters. The distributions include data from national and international studies such as resistance surveillance programs and distributions from published articles, the pharmaceutical industry drug development programmes, veterinary programmes and from individual laboratories. Histograms display wild type and non-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.

ECOFFinder. The previously available ECOFFinder program is no longer accessible on this website because, according to EUCAST procedures (SOP 10.2), setting ECOFFs or TECOFFs on single or already aggregated distributions is no longer acceptable. Software and procedures to set individual ECOFFs on 5 or more accepted distributions result in mean ECOFFs with confidence limits and an analysis of the quality of the procedure leading to the establishment of an ECOFF. Questions about this can be directed to the curators via the question form EUCAST wild type distributions. Questions regarding any already downloaded ECOFFinder version should be directed to John Turnidge, EUCAST Document and Technical Support (jturnidge[at]gmail.com).

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