Laboratory Diagnosis and Antimicrobial Susceptibility Testing of Nontuberculous Mycobacteria

Abstract

This chapter discusses principles and methods for the laboratory identification of nontuberculous mycobacteria (NTM) beginning with biochemical and chemotaxonomic methods [high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and gas-liquid chromatography (GLC)] which have widely been replaced by the more definitive molecular methods including commercial probe technology, gene sequencing, and more recently mass spectrometry (MS) using the matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF). The MALDI-TOF-MS currently remains non-validated or beyond the capability of many clinical laboratories to implement into the NTM identification algorithm. As with all molecular methodologies, the creation and maintenance of adequate databases are critical to the success of implementation of these techniques. Notably, only limited gene sequencing (i.e., 16S rRNA gene) has been addressed by the Clinical and Laboratory Standards Institute (CLSI), and strict cutoff values for other genes are currently not available.