Mycobacterium
genus in the family Mycobacteriaceae of bacteria.
Introduction
This genus includes many pathogens known to cause serious diseases in mammals, including tuberculosis and leprosy. Most mycobacteria are classified into two categories, the fast-growing kind and the slow-growing kind, and most mycobacteria share some common characteristics:
- They are widespread organisms, typically living in water (including tap water treated with chlorine) and food sources.
- They can colonize their hosts without the hosts showing any adverse signs. For example, millions of people around the world are infected with M. tuberculosis but will never know it because they will not develop symptoms.
- Mycobacterial infections are notoriously difficult to treat. The organisms are hardy and can survive long exposure to antibiotics, which naturally leads to antibiotic resistance. Most mycobacteria are susceptible to the antibiotics clarithromycin and rifamycin, but antibiotic-resistant strains are known to exist.
- Mycobacteria tend to be fastidious (difficult to culture), sometimes taking over two years to develop in culture.
Medical classification
Mycobacteria can be classified into several major groups for purpose of diagnosis and treatment:
- M. tuberculosis complex which can cause tuberculosis: M. tuberculosis, M. bovis, M. africanum, and M. micoti
- M. leprae which causes Hansen's disease or leprosy
- Nontuberculous mycobacteria (NTM) are all the other mycobacteria which can cause pulmonary disease resembling tuberculosis, lymphadenitis, skin disease, or disseminated disease.
Species
M. = Mycobacterium
- M. abscessus, which is also a common water contaminant and was until recently thought to be a subspecies of M. chelonae.
- M. africanum
- M. asiaticum
- M. avium complex (MAC), which is a significant cause of death in AIDS patients. This complex also includes M. avium paratuberculosis, which has been implicated in Crohn's disease in humans and Johne's disease in ovines.
- M. bovis
- M. chelonae, which is a common water contaminant and can also infect wounds.
- M. fortuitum
- M. gordonae
- M. haemophilum
- M. intracellulare
- M. kansasii, which can cause life-threatening infections in people with compromised immune systems
- M. leprae, which causes leprosy
- M. malmoense
- M. marinum
- M. microti
- M. scrofulaceum
- M. smegmatis
- M. tuberculosis, which causes tuberculosis
- M. ulcerans
- M. uvium
- tuberculosis
- Hansen's disease or leprosy
