NoMoReAMR

EUCAST

2 min read

EUCAST

The European Committee on Antimicrobial Susceptibility Testing (EUCAST) provides standardised breakpoints and methods for antimicrobial susceptibility testing across Europe. All Nordic countries follow EUCAST guidelines, ensuring comparability of AMR data.

What EUCAST Does

  • Sets MIC breakpoints - the minimum inhibitory concentration thresholds that determine whether a bacterium is:
    • S - Susceptible, standard exposure
    • I - Susceptible, increased exposure
    • R - Resistant
  • Provides standardised disk diffusion testing methods
  • Defines epidemiological cut-off values (ECOFFs) for distinguishing wild-type from non-wild-type populations (used in animal surveillance by EFSA)
  • Regularly updates breakpoints as scientific evidence evolves

Challenges with EUCAST Breakpoints

EUCAST breakpoints are updated regularly, which creates challenges for longitudinal surveillance:

  • Historical comparability: When breakpoints change, old data interpreted under previous breakpoints are no longer directly comparable with current data (see AST Reporting)
  • Raw data preservation: If only S/I/R interpretations are stored (not raw MIC or disk zone diameter data), retrospective re-analysis is impossible
  • Clinical context: Breakpoints are increasingly defined for specific clinical entities (UTIs, meningitis, endocarditis), meaning the S/I/R interpretation depends on the clinical setting

Proposed solution

Implementing a policy for storing raw MIC and disk zone data in national databases would allow retrospective analysis and consistent trend monitoring even when breakpoints change. See AST Reporting for details.

EUCAST in the Nordic Region

Before EUCAST, many Nordic countries used NCCLS/CLSI guidelines. By 2016, more than 50% of laboratories in the Nordic countries had implemented EUCAST breakpoints. Today, all Nordic surveillance programmes align with EUCAST:

Graph View