EUCAST disk diffusion test for routine antimicrobial susceptibility testing

During 2009 - 2010 EUCAST is developing a disk diffusion test for routine antimicrobial susceptibility testing. The method is derived from the Kirby-Bauer method, variants of which are currently widely used in Europe, but is calibrated to EUCAST MIC breakpoints.

The method is based on two media, Mueller-Hinton agar without supplements (MH) for non-fastidious organisms, including enterococci, and MH with 5 % horse blood and 20 mg β-NAD/L (MH-F) for Streptococcus spp. including Streptococcus pneumoniae, Haemophilus spp. and other fastidious organisms. 

The plates are incubated at 35 ± 1 ºC for 18 ± 2 h within 15 minutes from application of the disks. MH plates are incubated in air and MH-F plates in 5% CO2.

Breakpoint tables with tentative zone diameter breakpoints were published December 21, 2009.

EUCAST breakpoints and commercially available material and systems for AST - important information to laboratories - click here.