Definition:

Nontuberculous mycobacteria (NTM) are classified into 2 categories: slow-growing mycobacteria (SGM) and rapidly-growing mycobacteria (RGM), based on interval to colony formation by subculture on solid media. More than 50 species of RGM have been identified, more than a third of which are opportunistic human pathogens. The most frequently encountered RGM that cause human infections are Mycobacterium abscessus, Mycobacterium chelonae, Mycobacterium fortuitum (complex), Mycobacterium mucogenicum, and Mycobacterium neoaurum. RGM, generally of low virulence, are capable of causing a wide spectrum of infections. Many RGM species, well-known and recently described species, caused significant infections in patients with cancer, including catheter-related bacteremia, disseminated infection, bronchopulmonary infections, dermatitis, cellulitis, and others.