Mycobacteria are a large family of bacteria that comprises over 200 pathogenic and non-pathogenic species. The most well known are the human pathogens responsible for leprosy (M. leprae), for tuberculosis (M. tuberculosis), as well as the zoonotic agent responsible for bovine tuberculosis, which can therefore be transmitted from animals to humans (M. bovis). 

What are mycobacteria? And what pathologies do they cause?

There are currently >200 species of mycobacteria, comprising:

  • Nonculturable mycobacteria such as Mycobacterium leprae, the agent for leprosy
  • the mycobacteria of the M. tuberculosiscomplex, agents for tuberculosis (M. tuberculosis, M. africanum, M. bovis, etc.)
  • non-tuberculous mycobacteria also known as atypicalmycobacteria. Of these, some are strictly human pathogens (i.e. agents that cause diseases), such as M. ulcerans, which causes disorders in the patient it infects. Others are opportunistic, causing, in certain circumstances, diseases called mycobacterioses. This last type of nontuberculous mycobacteria is, however, very rarely pathogenic.

What is tuberculosis?

Tuberculosis is an infectious disease caused principally by the bacterium Mycobacterium tuberculosis (M. tb) for which transmission is airborne. Some cases of tuberculosis also have a zoonotic origin (transmission from animal to humans). 

More information on tuberculosis 

What is mycobacteriosis?

Mycobacterioses are opportunistic infections caused by mycobacteria other than the bacteria responsible for tuberculosis and leprosy. They are called “atypical” in order to distinguish them from tuberculous bacteria.

Mycobacterioses can present in 4 forms :

  • pulmonary infection
  • lymphadenitis
  • a skin disease (soft tissue/joints/skeleton) 
  • disseminated infection.

The main agents responsible for mycobacterioses are Mycobacterium avium, M. chimaera/M. intracellulare, M. xenopi, M. kansasii, M. abscessus, M. chelonae and M. fortuitum, M. simae and M. marinum.

Sciensano contributes to the rapid diagnosis of infections caused by mycobacteria as well as to the monitoring the resistance of these bacteria to antibiotics.  Sciensano is also responsible for detecting epidemics and develops new vaccines and more effective treatments to prevent infections and the spread of mycobacteria.

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