ABSTRACT
The genus Mycobacterium consists of more than 190 species and belongs to the family of Mycobacteriaceae, order Corynebacteriales, phylum/class Actinobacteria, and kingdom Bacteria (https://www.dsmz.de/bacterial-diversity/prokaryotic-nomenclature-up-to-date). 1 Mycobacteria are nonmotile, rod-shaped bacilli, characterized by an extremely lipid-rich cell wall comprising mycolic acids. These long-chain (C-60 to C-90) fatty acids make all mycobacterial species “acid-fast” as they resist acid-alcohol decolorization following staining with phenicated dyes like fuchsine, enabling their microscopic detection. Mycobacteria should not be confused with members of the closely related genera Nocardia, Corynebacterium, or Rhodococcus, which have shorter-chain (C-22 to C-64) mycolic acids and can be partially acid-fast. 1
