The EUCAST Subcommittee on MIC distributions and ECOFFs
In 2002, EUCAST launched the concept of gathering large numbers of MIC values to present as aggregated MIC distributions for each species-agent combination and to determine epidemiological cut-off values (ECOFF) on. The distributions are for bacteria and fungi and for antimicrobial agents that are or have been used in human and veterinary medicine. Only MIC distributions that adhered to a set of basic conditions were accepted for aggregation with other distributions (see introductory notes on the EUCAST MIC distribution website (http://mic.eucast.org/Eucast2/).
There are currently more than 35 000 MIC distributions in the EUCAST database, which amounts to several million MIC values. An aggregated distribution may consist of over 90000 MIC values (e.g. the aggregated distributions of cefuroxime MICs for Escherichia coli and of vancomycin MICs for Staphylococcus aureus). The distributions are presented as tables and as histograms. The MIC distributions are from a wide variety of sources including breakpoint committees, individual researchers in human and veterinary medicine, programmes for the surveillance of antimicrobial resistance in humans and animals and EUCAST development projects, or have been put together by pharmaceutical companies during programmes for the development of new agents.
In 2015 EUCAST decided to form a subcommittee to determine rules for MIC distributions (import and aggregation) and for determining ECOFFs. It was also decided to appoint curators of the database.
A position document was developed during 2016 and was published as an SOP (No 10) in 2017 and later updated to 10.1 and 10.2.
The subcommittee is now dormant and day-to-day business is handled by the former chair Gunnar Kahlmeter and Secretary John Turnidge.
Two publications detail the background and development of MIC and Zone diameter distributions and how ECOFFs are determined.
Wild-type distributions of minimum inhibitory concentrations and epidemiological cut-off values-laboratory and clinical utility. Gunnar Kahlmeter & John Turnidge. Clin Microbiol Rev. December 1, 2023.
How to: ECOFFs – the why, the how and the don´ts of EUCAST epidemiological cutoff values. G Kahlmeter, J. Turnidge. A narrative review, CMI 2022. https://doi.org/10.1016/j.cmi.2022.02.024
