<i>Mycobacterium</i> : Clinical and Laboratory Characteristics of Rapidly Growing Mycobacteria

Abstract Rapidly growing mycobacteria (RGM) contain long‐chain fatty acids, known as mycolic acids, that can be quantitated with chromatographic techniques such as high‐performance liquid chromatography (HPLC). Prior to the molecular era, HPLC was used for identification of RGM species in most major reference laboratories. The RGM are opportunistic pathogens that cause disease in a variety of clinical settings. RGM may also cause bone and joint infections. Chronic lung infections with RGM, most often in nonsmoking older women with bronchiectasis, are sometimes associated with the Mycobacterium avium complex. The use of mycobacterial smears is a rapid and reasonably sensitive step in the diagnosis of RGM disease. PCR amplification and sequencing has been used to detect and identify nontuberculous mycobacteria in specimens from sterile sites, but these tests are generally limited to larger, reference laboratories. The adjunctive nonmolecular tests, including antimicrobial susceptibility tests, have been utilized for preliminary identification of the RGM.