Media Preparation

EUCAST antimicrobial susceptibility testing is based on MH agar and MH broth, without supplements for non-fastidious organisms and with supplements for fastidious organisms (Streptococci, Haemophilus influenzae, Campylobacter and others as indicated in the breakpoint tables). The plate and broth for fastidious organisms are named MH-F plates and MH-F broth.

Mueller-Hinton agar with 5% mechanically defibrinated horse blood and 20 mg/L β-NAD (MH-F) continues to be the EUCAST recommended medium for AST of fastidious organisms. However, plates where horse blood is exchanged for sheep blood (MH-S) can with one exception be used instead – the exception is Haemophilus spp.