The list of clinically important slow-growing nontuberculous mycobacteria (NTM) continues to expand as new species are identified and older ones are found to be pathogenic. More detailed information on these organisms (including many not covered in this chapter) can be found in a number of excellent reviews (1 - 5). As a group, these mycobacteria currently cause fewer infections than those species discussed in previous chapters. Some of these organisms are not newly discovered but have heretofore been considered virtually nonpathogenic. Previously, many were regarded as contaminants when isolated from clinical specimens. Timpe and Runyon established that these organisms could cause disease in humans and classified them based on pigment production, growth rate, and colonial characteristics. Photochromogens (group I) grow slowly on culture media (>7 days). Their colonies change from a buff shade to bright yellow or orange after exposure to light. Scotochromogens (group II) also grow slowly but demonstrate pigmented colonies when incubated in the dark or the light. Group III mycobacteria grow slowly and lack pigment in the dark or light. Rapid growers (group IV) also lack pigment, but they grow in culture within 3 to 5 days. Collectively, these four groups have been called the “atypical mycobacteria,” NTM, mycobacteria other than tubercle bacilli, or “potentially pathogenic environmental mycobacteria.” Molecular techniques such as DNA probes, real-time PCR, and gene amplification and restriction length polymorphism are useful tools for rapid identification of NTM (5 - 7).
|Original language||English (US)|
|Title of host publication||Tuberculosis and Nontuberculous Mycobacterial Infections|
|Number of pages||10|
|State||Published - Jan 1 2017|
All Science Journal Classification (ASJC) codes
- Immunology and Microbiology(all)