Mycobacterium avium subsp. avium is a species of the phylum Actinobacteria (Gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus Mycobacterium. The type strain is ATCC 25291 = CCUG 20992 = CIP 104244 = DSM 44156 = NCTC 13034. The subspecies name Mycobacterium avium subsp. avium Chester 1901 is automatically created by the valid publication of Mycobacterium avium subsp. paratuberculosis (Bergey et al. 1923) and the valid publication of Mycobacterium avium subsp. silvaticum Thorel et al. 1990.