2.1 General features
Non tuberculosis Mycobacteria (NTM) are not members of the MTBC or ”Mmycobacteria other than tuberculosis (MOTT)”. Since these bacteria were different from the usual mycobacterial strains, they were also referred as ”atypical” originating from the misguided belief that they were uncommon strains of MTb MTB (Falkinham 1996).
Non-tuberculous Mycobacteria (NTM) are natural inhabitants of soil, dust, water and animal bedding (Cvetnic et al., 2007; Krizova et al., 2010; Ofukwu and Akwuobu, 2010; Agdestein et al., 2011) and have the ability to cause diseases in humans (Raviglione 2004; Heifets 2004) and animals. As oftenusuallu, causeit cause lymphadenitis, lung infections, skin and soft tissue infections mainly in immune-compromised hosts (Khan et al., 2007).
More than 150 species of Mycobacteria are known today (Tortoli 2014) and at least 40 of them are associated with lung disorders (Griffith 2010).
The genus harbors three major groups, the Mycobacterium tuberculosis complex (MTBC), the Mycobacterium leprae and all other non-tuberculosis mycobacteria (NTM) (Jang et al., 2008).
The NTM can be classified according to the growth rate into rapid growing mycobacteria (RGM) form visible colonies in agar plates within 3-7 days, while slow growing mycobacteria (SGM) require more than 7 days to form visible colonies in agar plates (Kim et al. 2013).
Mycobacterium avium complex (MAC), the most prominent of the SGM includes several species and subspecies like the M. avium and M. intracellulare (Ignatov et al., 2012). M. avium is further divided in four subspecies that show differences in life style, ranging from environmental bacteria that are opportunistic pathogen for humans to animal pathogens (Rue-Albrecht et al., 2014) and these subspecies are;
Mycobacterium avium hominissuis (MAH) which predominantly causes infection to human, Mycobacterium avium avium (MAA) and Mycobacterium avium silvaticum (MAS) cause bird tuberculosis and Mycobacterium avium paratuberculosis (MAP) is the reason behind Johne´s disesasdisease of cattle (Van Ingen et al., 2013).
Mycobacteria are aerobic and non-motile bacteria (except Mycobacterium marinum which has been shown to be motile within macrophage) (Ryan and Ray 2004). Mycobacteria are neither Gram-positive neither gram negative. They have a thin, gram negative-like peptidoglycan (Faller et al., 2004) and have an unusual, waxy cell envelope containing specifically long chained mycolic acids. This cell envelope helps pathogenic Mmycobacteria to resist dehydration, antimicrobial drugs and host defenses. Mycolic acids confer the characteristic ability to resist decolorization by acidic ethanol following staining with basic fuchsin to Mmycobacteria and some closely related actinomycetes, a property (still) widely used for the fast recognition of Mmycobacteria (Pfyffer 2007).
2.2 Geographical distribution:
2.1 General features