Atypical mycobacteria

Non-tuberculous or atypical mycobacteria are widely distributed, in free form, in the hydrotelluric environment (water, soil, plants) where they are capable of surviving and multiplying.
They are isolated from drinking water supplied after treatment, and are usually in biofilms.

Over 80 species have been described, but only about twenty have been recognised as potentially pathogenic to man.

They are capable of developing across a wide range of pH (from 1 to 5), in temperatures between 28°C and 52°, in a saline environment.

They are more strongly resistant to chlorine disinfection and can escape the effects of disinfectants if they are phagocyted by protozoa such as amoeba. Contamination is often reduced by temperatures above 70°C.

All these properties help them to survive, and even to grow in the natural aquatic environment, in treated drinking water, in pools and aquariums, making these media infectious to man.

Infections caused by these mycobacteria are mainly pulmonary but ganglionic, osteoarticular, cutaneous and sub-cutaneous localisations and general infections can also occur.

Mycobacteria of the M. avium intracellulare complex are responsible for pulmonary disorders similar to tuberculosis, cervical adenitis in children and skin lesions.

In view of their extensive distribution in the environment and the possible colonisation of water supply systems, it is important to assess the risk of contamination by non-tuberculous mycobacteria, and especially for sensitive and vulnerable individuals.