scope:

The purpose and guidance set forth in this document are intended for use by manufacturers of Mueller- Hinton agar to assess the quality of their production lots of media by comparison with reference lots of Mueller-Hinton agar evaluated by the CLSI Subcommittee on Culture Media. The scope of this document:

• enables manufacturers of Mueller-Hinton agar to ensure that their production lots perform in disk diffusion susceptibility tests in a manner equivalent to the protocols detailed in CLSI document M2- Performance Standards for Antimicrobial Disk Susceptibility Tests;
• provides the Subcommittee on Culture Media with a process to regularly identify new reference standards (primary and secondary lots) of Mueller-Hinton agar for use by manufacturers of the agar medium; and
• provides the Subcommittee on Culture Media with a process to periodically assess the stability of the primary and secondary reference lots of Mueller-Hinton agar.

In this edition of the document, the subcommittee has added criteria for manufacturers to test their production lots of Mueller-Hinton agar against fastidious organisms (specifically Haemophilus influenzae and Streptococcus pneumoniae), since these species are regularly tested by disk diffusion methods in routine diagnostic clinical laboratories.