Mycobacterium kansasii explained

Mycobacterium kansasii is a bacterium in the Mycobacterium genus. It is an environmental bacteria that causes opportunistic infections in humans, and is one of the leading mycobacterial causes of human disease after tuberculosis and leprosy.[1]

Description

Gram-positive, nonmotile, moderately-long to long, and acid-fast rods.

Colony characteristics

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. Oxygen is essential for the development of the pigment. If grown in a lighted incubator, most strains form dark red crystals of β-carotene on the surface and inside of colony.

Physiology

Its physiology is described as growth on Middlebrook 7H10 agar at 37°C within 7 days or more,resistant to pyrazinamide andsusceptible to ethambutol.

Differential characteristics

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.

M. kansasii complex

Several former subtypes of M. kansasii have been reclassified as closely related species, and along with M. gastri form the M. kansasii complex (MKC). The species in the MKC are

Discovery

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 the University of Kansas Medical Center.[5]

Pathogenesis

M. kansasii may cause chronic human pulmonary disease resembling tuberculosis. Extrapulmonary infections, such as cervical lymphadenitis in children, cutaneous and soft tissues infections, and musculoskeletal system involvement are uncommon. Rarely it causes disseminated disease in patients with severely impaired cellular immunity (such as organ transplants or AIDS). Pre-existing lung disease such as silicosis is a risk factor.[6] Mycobacterium kansasii occasionally involves the skin in a sporotrichoid pattern.[7] 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.[8] Biosafety level 2 is indicated.

Type strain

First and most frequently isolated from human pulmonary secretions and lesions.

Strain ATCC 12478 = CIP 104589 = DSM 44162 = JCM 6379 = NCTC 13024.

External links

Notes and References

  1. Johnston JC, Chiang L, Elwood K . Mycobacterium kansasii . Microbiology Spectrum . 5 . 1 . January 2017 . 28185617 . 10.1128/microbiolspec.TNMI7-0011-2016 . Schlossberg D .
  2. Luo T, Xu P, Zhang Y, Porter JL, Ghanem M, Liu Q, Jiang Y, Li J, Miao Q, Hu B, Howden BP, Fyfe JA, Globan M, He W, He P, Wang Y, Liu H, Takiff HE, Zhao Y, Chen X, Pan Q, Behr MA, Stinear TP, Gao Q . 6 . Population genomics provides insights into the evolution and adaptation to humans of the waterborne pathogen Mycobacterium kansasii . Nature Communications . 12 . 1 . 2491 . May 2021 . 33941780 . 8093194 . 10.1038/s41467-021-22760-6 . 2021NatCo..12.2491L .
  3. Tagini F, Aeby S, Bertelli C, Droz S, Casanova C, Prod'hom G, Jaton K, Greub G . 6 . Phylogenomics reveal that Mycobacterium kansasii subtypes are species-level lineages. Description of Mycobacterium pseudokansasii sp. nov., Mycobacterium innocens sp. nov. and Mycobacterium attenuatum sp. nov . International Journal of Systematic and Evolutionary Microbiology . 69 . 6 . 1696–1704 . June 2019 . 30950782 . 10.1099/ijsem.0.003378 . 96435266 . free .
  4. Jagielski T, Borówka P, Bakuła Z, Lach J, Marciniak B, Brzostek A, Dziadek J, Dziurzyński M, Pennings L, van Ingen J, Žolnir-Dovč M, Strapagiel D . 6 . Genomic Insights Into the Mycobacterium kansasii Complex: An Update . Frontiers in Microbiology . 10 . 1 . 2918 . Jan 2020. 32010067 . 6974680 . 10.3389/fmicb.2019.02918 . free .
  5. Buhler VB, Pollak A . Human infection with atypical acid-fast organisms; report of two cases with pathologic findings . American Journal of Clinical Pathology . 23 . 4 . 363–374 . April 1953 . 13040295 . 10.1093/ajcp/23.4.363 .
  6. Webster Jr JR, Cugell DW, Bazley ES, Harrison III RW, Bugaieski SM, Buckingham WB . 1969-06-01 . Silicosis and Mycobacterium Kansasii Infection . Diseases of the Chest . 55 . 6 . 479–482 . 10.1378/chest.55.6.479.
  7. Book: James WD, Berger TG . Andrews' Diseases of the Skin: clinical Dermatology . Saunders Elsevier . 2006 . 978-0-7216-2921-6 . etal.
  8. Vaerewijck MJ, Huys G, Palomino JC, Swings J, Portaels F . Mycobacteria in drinking water distribution systems: ecology and significance for human health . FEMS Microbiology Reviews . 29 . 5 . 911–934 . November 2005 . 16219512 . 10.1016/j.femsre.2005.02.001 . free .

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