Now no longer commonly used term for the group of "nontuberculous mycobacteria" (NTM). NTMs cause infectious diseases that have become increasingly important in recent years. The terms "atypical mycobacteria, or "mycobacteria other than tuberculosis" (MOTT) are obsolete in that the bacteria in this group are by no means "atypical".
Originally, the term "atypical mycobacteriosis" was most often understood to be synonymous with Mycobacterium avium complex (MAC) infections. While MAC is by far the most common pathogen, there are a variety of other atypical mycobacteria that cause similar disease patterns.
See below NTM (overview)