Mycobacterium kansasii
Mycobacterium kansasii is a bacterium in the Mycobacterium family. The genus includes species known to cause serious diseases in mammals, including tuberculosis and leprosy,[2] but this species is generally not dangerous to healthy people.
Description
Gram-positive, nonmotile, moderately long to long and acid-fast rods.
Colony characteristics
- Smooth to rough colonies after 7 or more days of incubation.
- Colonies grown in dark are nonpigmented, when grown in light or when young colonies are exposed briefly to light, colonies become brilliant yellow (photochromogenic).
- If grown in a lighted incubator, most strains form dark red crystals of β-carotene on the surface and inside of colony.
Physiology
Differential characteristics
- 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.
Pathogenesis
- Chronic human pulmonary disease resembling tuberculosis (involvement of the upper lobe).[3]
- 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.[4]
- Mycobacterium kansasii occasionally involves the skin in a sporotrichoid pattern.[5]: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
Type Strain
- First and most frequently isolated from human pulmonary secretions and lesions.
Strain ATCC 12478 = CIP 104589 = DSM 44162 = JCM 6379 = NCTC 13024.
References
- ^ Hauduroy,P. 1955. Derniers aspects du monde des mycobactéries. Masson et Cie, Paris, 1955.
- ^ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
- ^ http://emedicine.medscape.com/article/223230-overview
- ^ Wintrobe, Maxwell Myer (2004). Wintrobe's clinical hematology. John G. Greer; John Foerster, John N. Lukens, George M Rodgers, Frixos Paraskevas (11 ed.). Hagerstown, MD: Lippincott Williams & Wilkins. pp. 2467. ISBN 0-7817-3650-1.
- ^ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0.
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Slowly growing
(R1P=photochromogenic;
R2S=scotochromogenic;
R3N=nonchromogenic) |
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Long helix 18
(TKHGC)
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M. tuberculosis group
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K/H groups
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M. kansasii group
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M. haemophilum group
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M. conspicuum group
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Long helix 18
(other)
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M. xenopi group
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M. celatum group
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M. hiberniae group
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Short helix 18
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Ungrouped
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Rapidly growing/
Runyon IV |
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M. neoaurum group
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F/T groups
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M. fortuitum group
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M. vaccae group
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M. smegmatis group
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M. chelonae group
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M. elephantis group
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