EUCAST Disk Diffusion Test

EUCAST has developed a European disk (not tablet) diffusion test based on MH-agar and disks from several manufacturers for non-fastidious organisms and on  MH-agar with 5% defibrinated horse blood and 20 mg/L beta-NAD (MH-F) for fastidious microorganisms (streptococci, H.influenzae and others). Tentative breakpoints were published on the 21st of December, 2009.

Manufacturers of disks, tablets, media and automated AST systems are working to calibrate their products to the EUCAST standards. Some are ready while others are still facing difficulties. Users of European breakpoints are adviced to consult with EUCAST before choosing AST systems alternative to: 
1. MIC-determination using European breakpoints
2. European disk test method calibrated to European breakpoints
3. Automated susceptibility testing with a machine validated for use with European breakpoints.

Laboratories are invited to participate in the further development of the disk test by sending us zone diameter/MIC-correlates or by developing correlates for isolates with known MICs. You can read more about the invitation in this document:

Invitation to develop the European disk diffusion test