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Mycobacterium is the only genus in the family Mycobacteriaceae of bacteria.

1 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.
• All mycobacteria are aerobic and acid fast . As a genus, they share a characteristic cell wall, thicker than in many other bacteria, hydrophobic, waxy and rich in mycolic acids / mycolates . The mycobacterial cell wall makes a substantial contribution to the hardiness of this genus.
• 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. As well as being fastidious, some species also have extremely long reproductive cycles ( M. leprae, for example, may take more than 20 days to proceed through one division cycle; E. coli, for comparison, takes only half an hour ), making laboratory culture a slow process.

2 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 diseaseHansen's disease also known as leprosy is an infectious disease caused by infection by Mycobacterium leprae''. The modern name of the disease comes from the discoverer of Mycobacterium leprae G. Sufferers from Hansen's disease have generally been called l or leprosy
• Nontuberculous mycobacteria (NTM) are all the other mycobacteria which can cause pulmonary disease resembling tuberculosis, lymphadenitis, skin disease, or disseminated disease.

3 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 AIDSAIDS Acquired Immunodeficiency Syndrome or Acquired Immune Deficiency Syndrome sometimes written Aids is a human disease characterized by progressive destruction of the body's immune system. It is widely accepted that AIDS results from infection with HIV patients. This complex also includes M. avium paratuberculosis, which has been implicated in Crohn's diseaseCrohn's Disease is a chronic inflammatory disease of the alimentary tract and it can involve any part of it from the mouth to the anus. It typically affects the terminal ileum and well demarcated areas of large bowel with relatively normal bowel. It is of in humans and Johne's diseaseJohne's disease (pronounced "yo-knees") is a contagious, chronic and usually fatal infection that affects primarily the small intestine of ruminants. All ruminants are susceptible to Johne's disease, which is sometimes called paratuberculosis . The diseas in sheepThis article is about the animal; for other meanings of Sheep see Sheep (disambiguation). A sheep is any of several woolly ruminant quadrupeds, but most commonly the Domestic Sheep Ovis aries , which probably descends from the wild urial of south-central.
• 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 systemThe immune system is any system present in an organism to prevent predation by biological agents. All living organisms have these protective measures, although they vary radically in scope and mechanism. In humans and domesticated animals, the immune systs
• M. leprae, which causes leprosy
• M. malmoense
• M. marinum
• M. microti
• M. scrofulaceum
• M. smegmatis
• M. tuberculosis, which causes tuberculosis
• M. ulcerans
• M. uvium
• M. xenopi