| Mycobacterium kansasii | |
|---|---|
 | |
Scientific classification | |
| Domain: | Bacteria |
| Kingdom: | Bacillati |
| Phylum: | Actinomycetota |
| Class: | Actinomycetes |
| Order: | Mycobacteriales |
| Family: | Mycobacteriaceae |
| Genus: | Mycobacterium |
| Species: | M. kansasii |
| Binomial name | |
| Mycobacterium kansasii Hauduroy 1955,[1] ATCC 12478 | |
Mycobacterium kansasii is abacterium in theMycobacteriumgenus. It is an environmental bacteria that causesopportunistic infections in humans, and is one of the leading mycobacterial causes of human disease aftertuberculosis andleprosy.[2]
Gram-positive, nonmotile, moderately-long to long, andacid-fast rods.
It forms smooth to roughcolonies 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 theRunyon classification of Non-Tuberculous Mycobacteria. Oxygen is essential for the development of the pigment. If grown in a lighted incubator, most strains form dark red crystals ofβ-carotene on the surface and inside of colony.
Its physiology is described as growth on Middlebrook 7H10 agar at 37°C within 7 days or more,resistant topyrazinamide andsusceptible toethambutol.
It is closely related to the non-pathogenic, also slowly growing, nonpigmented,M. gastri.Both species share an identical16S rDNA but differentiation is possible by differences in theITS and hsp65 sequences.A commercial hybridisation assay (AccuProbe) to identifyM. kansasii exists.
Several former subtypes ofM. kansasii have been reclassified as closely related species, and along withM. gastri form theM. kansasii complex (MKC). The species in the MKC are
Mycobacterium kansasii was first described in 1952 after being identified as the cause of two cases of disease resembling human pulmonary tuberculosis at Kansas City General Hospital and theUniversity of Kansas Medical Center.[6]
M. kansasii may cause chronic humanpulmonary disease resemblingtuberculosis.[7] Extrapulmonary infections, such ascervical lymphadenitis in children,cutaneous and soft tissues infections, and musculoskeletal system involvement are uncommon. Rarely it causes disseminated disease in patients with severely impairedcellular immunity (such asorgan transplants orAIDS). Pre-existing lung disease such as silicosis is a risk factor.[8]Mycobacterium kansasii occasionally involves the skin in a sporotrichoid pattern.[9]: 341 It is unclear where people acquire the infection and person-to-person spread is not thought to occur.Tap water is believed to be the major reservoir associated with human disease.[10]Biosafety level 2 is indicated.
First and most frequently isolated from human pulmonary secretions andlesions.
StrainATCC 12478 = CIP 104589 = DSM 44162 = JCM 6379 = NCTC 13024.
