scope:

This document contains protocols for the susceptibility testing of three major categories of mycobacterial species: 1) Mycobacterium tuberculosis complex (MTBC), 2) the slowly growing, nontuberculous mycobacteria (NTM), and 3) the rapidly growing mycobacteria. Additionally, recommendations for susceptibility testing of Nocardia spp. and miscellaneous aerobic actinomycetes are included in this document. M24-A contains guidance on the selection of primary and secondary agents for testing and reporting; instructions for performing the standard agar proportion method and other reference methods (e.g., broth micro- and macrodilution for Mycobacterium avium complex and broth microdilution for rapidly growing mycobacteria); and quality control protocols for each organism category. Testing and reporting recommendations and principles of quality control procedures apply to using commercial FDAcleared systems as well as the reference methods. It is anticipated that further refinement of these protocols will occur as laboratories involved in the regular testing of these organism types gain experience with the use of this document. To facilitate further development of M24, the subcommittee requests comments and suggestions for improvement with regard to the methods included herein.