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.

Rosco has distributed a letter concerning EUCAST breakpoints and their validity for users of Rosco tablets. EUCAST has not in any way been involved or consulted in the calibration of Rosco material to the European disk test. No proof or documentation has been submitted to EUCAST to explain why Rosco does not adhere to EUCAST recommendations. 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