Mycobacteria are bacteria that are taxonomically grouped within the Phylum Actinobacteria, which are environ­mental and soil-associated organisms noted for their fungus-like qualities.

Accordingly, the clinical and path­ological features of mycobacterial disease are reminiscent of fungal infection: a tendency to produce chronic pro­gressive granulomatous lesions and relative resistance to medical therapy.

Mycobacteria are separated into two broad groups: ‘tuberculous mycobacteria’ (TM) and ‘non-tuberculous mycobacteria’ (NTM). This chapter primarily deals with NTM, which, of the two groups is significantly more common in Australian mammals. The pathology, epide­miology, and zoonotic potential of the two groups are quite distinct and should be considered separately in the clinical context (Table 22.1).

Natural infection of Australian mammals with TM is primarily confined to pinnipeds infected with Mycobac­terium pinnipedii (see Chapter 45). Infection of Austral­ian terrestrial mammals with TM is covered in section 2 of this chapter.

Review of cases in the literature (1900-2018), the Aus­tralian Registry of Wildlife Health (ARWH) (1998-2018), and eWHIS (Australia’s National Wildlife Health Infor­mation System) (2008-2018) reveal that at least 17 NTM and three TM species have been documented to cause disease in various Australian mammals (Tables 22.2 and 22.3). A small number of specific mycobacterial diseases are particularly significant in terms of frequency of occurrence in Australian mammals or the serious impli­cations for humans, other animals and/or national biose­curity (Table 22.2).

1.