Mycobacterium avium subspecies paratuberculosis

Other Scientific Names

• Mycobacterium avium subsp. paratuberculosis
• Mycobacterium chronicae pseudotuberculosae bovis

International Common Names

• English: Mycobacterium paratuberculosis

• Domain: Bacteria
•     Phylum: Actinobacteria [phylum]
•         Class: Actinobacteria
•             Subclass: Actinobacteridae
•                 Order: Actinomycetales
•                     Suborder: Corynebacterineae
•                         Family: Mycobacteriaceae
•                             Genus: Mycobacterium
•                                 Species: Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis causes paratuberculosis (Johne's disease) in cattle and other ruminants.

M. avium subsp. paratuberculosis is a small (0.5 µm x 1.5 µm), facultative, acid-fast bacterium. The bacteria grow in clumps due to the complex cell wall formed by peptidoglycolipids (Merkal et al., 1973; Brennan and Nikaido, 1995). On agar medium, M. avium subsp. paratuberculosis grows as small, opaque colonies with a mixture of smooth and rough morphologies. Primary isolation and propagation of M. avium subsp. paratuberculosisin vitro requires mycobactin, an iron-chelating agent produced by most species of mycobacteria. Although M. avium subsp. paratuberculosis is capable of scavenging iron in vivo, it is dependent upon the addition of exogenous mycobactin or other iron sources to synthetic medium in order to grow in vitro (Lambrecht and Collins, 1992). Primary culture of M. avium subsp. paratuberculosis from tissue or faecal samples takes 12-16 weeks (longer for MAP-S strains) on agar medium such as Herrold's egg yolk or Lowenstein-Jensen medium, although recovery rates are shorter for heavily infected tissues. Primary isolation of M. avium subsp. paratuberculosis using liquid medium formulations has improved the rates of recovery (Shin et al., 2007; Whittington et al., 2013; Whittington, 2020). Biochemical characteristics of M. avium subsp. paratuberculosis may vary between strains, although there is evidence to suggest that the neutral red test may be used to determine virulence of M. avium subsp. paratuberculosis strains, and that catalase activity may be useful to discriminate between M. avium subsp. paratuberculosis and other species of mycobacteria (Merkal and Thurston, 1966; Thorel et al., 1990).

Disease(s) associated with this pathogen is/are on the list of diseases notifiable to the World Organisation for Animal Health (OIE). The distribution section contains data from OIE's Handistatus database on disease occurrence. For further information from OIE, see the website: www.oie.int.