INTRODUCTION
DOLORES GAVIER-WIDEN1, MARK CHAMBERS2,
Christian gortazar3 and richard delahay4
1National Veterinary Institute (SVA), and Swedish University of Agricultural Sciences Uppsala, Sweden
2TB Research Group, Department of Bacteriology, Animal Health and Veterinary Laboratories Agency, Weybridge, UK 3IREC National Wildlife Research Institute (CSIC-UCLM- JCCM), Ciudad Real, Spain
4The Food and Environment Research Agency, Woodchester Park, Nympsfield, Gloucestershire, UK
The Mycobacterium genus belongs to the family Mycobac- teriaceae, which has more than 100 members and comprises saprophytes, opportunists and obligate pathogens.
The genus includes the slow-growing M. tuberculosis and M. avium complexes. The members of the Mycobacterium tuberculosis complex (MTBC) are the causative agents of human and animal tuberculosis. The MTBC includes Mycobacterium bovis, the aetiologic agent of bovine tuberculosis, M. caprae, a species closely related but distinct from M. bovis, also causing tuberculosis in animals, M. tuberculosis, the most common cause of human tuberculosis, and M. africanum, M. canetti, M. microti and M. pinnipedii. The M. avium complex (MAC) includes two main species: M. avium and M. intracellulare. Mycobacterium avium comprises the following subspecies ofveterinary importance: M. avium subsp. avium,M. avium subsp. hominissuis, M. avium subsp. paratuberculosis and M. avium subsp. silvaticum.All mycobacteria are rod-shaped, about 0.5 μm wide, variable in length, aerobic, non-spore forming and characteristically acid-alcohol fast, staining bright red using the Ziehl-Neelsen (ZN) stain. Although not strictly Grampositive, they are classified as acid-fast Gram-positive bacteria because of their lack of an outer cell membrane.
All Mycobacteria have a characteristic cell wall, thicker than in many other bacteria, which is hydrophobic, waxy, and rich in mycolic acids and mycolates. This lipid-rich, complex cell wall protects the mycobacteria from being killed in the phagolysosome and plays a role in the survival of the bacteria in macrophages. Parts of the cell wall are immunostimulatory and form the basis for vaccine adjuvants. Biochemical tests and culture characteristics help to differentiate species of mycobacteria but cannot identify them all; therefore molecular methods are used for species classification and phylogeny.Tuberculosis refers to diseases caused by members of the MTBC, mainly M. tuberculosis and M. bovis. Mycobacte- riosis is the term used to refer to infection by other mycobacterial species: atypical mycobacteria or non-tuberculous mycobacteria.
Infectious Diseases of Wild Mammals and Birds in Europe, First Edition. Edited by Dolores Gavier-Widen, J. Paul Duff, and Anna Meredith. © 2012 Blackwell Publishing Ltd. Published 2012 by Blackwell Publishing Ltd. Material authored by Mark Chambers remains Crown Copyright.