Mycobacterial susceptibility testing and reporting: When, how, and what to test

Mycobacterial susceptibility testing is important for the management of patients with tuberculosis and those with diseasescaused by certain nontuberculous mycobacteria. To help standardize methods used for testing susceptibility of mycobacteria, in 2003 the National Committee for Clinical Laboratory Standards (NCCLS) published M24-A, the approved standard for susceptibility testing of mycobacteria, nocardiae, and other aerobic actinomycetes. This standard contains guidelines for testing Mycobacterium tuberculosis complex; select, slow-growing, nontuberculous mycobacteria, including Mycobacterium avium complex, Mycobacterium kansasii, and Mycobacterium marinum; and the fast-growing mycobacteria, as well as Nocardia, and other aerobic actinomycetes. The recommendations outlined in M24-A that address mycobacterial susceptibility testing are reviewed here.