Hauduroy 1955, ATCC 12478
Mycobacterium kansasii is a bacterium in the Mycobacterium family. The genus includes species known to cause serious diseases in mammals, including tuberculosis and leprosy, but this species is generally not dangerous to healthy people.
It forms smooth to rough colonies after 7 or more days of incubation and is considered a slow grower. Colonies grown in dark are nonpigmented, when grown in light or when young colonies are exposed briefly to light, colonies become brilliant yellow (photochromogenic) according to the Runyon classification of Non-Tuberculous Mycobacteria. If grown in a lighted incubator, most strains form dark red crystals of β-carotene on the surface and inside of colony.
It is closely related to the non-pathogenic, also slowly growing, nonpigmented, M. gastri. Both species share an identical 16S rDNA but differentiation is possible by differences in the ITS and hsp65 sequences. A commercial hybridisation assay (AccuProbe) to identify M. kansasii exists.
Chronic human pulmonary disease resembling tuberculosis (involvement of the upper lobe). Extrapulmonary infections, (cervical lymphadenitis in children, cutaneous and soft tissues infections and musculoskeletal system involvement), are uncommon. Rarely causes disseminated disease except in patients with severely impaired cellular immunity (patients with organ transplants or AIDS). Patients with silicosis are at risk. Also appears in patients with hairy cell leukemia, but not in other lymphoproliferative disorders. Mycobacterium kansasii occasionally involves the skin in a sporotrichoid pattern.:341 Normally considered not to be contagious from person to person. Natural sources of infections unclear. Tap water is believed to be the major reservoir associated with human disease. Biosafety level 2 is indicated.
First and most frequently isolated from human pulmonary secretions and lesions.
Strain ATCC 12478 = CIP 104589 = DSM 44162 = JCM 6379 = NCTC 13024.