Mycobacterium kansasii

Mycobacterium kansasii
Mycobacterium kansasii
Scientific classification
Kingdom: Bacteria
Phylum: Actinobacteria
Order: Actinomycetales
Suborder: Corynebacterineae
Family: Mycobacteriaceae
Genus: Mycobacterium
Species: M. kansasii
Binomial name
Mycobacterium kansasii
Hauduroy 1955,[1] 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,[2] but this species is generally not dangerous to healthy people.



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.


  • Growth on Middlebrook 7H10 agar at 37°C within 7 days or more.
  • Resistant to pyrazinamide.
  • Susceptible to ethambutol.

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.


  • 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.


  1. ^ Hauduroy,P. 1955. Derniers aspects du monde des mycobactéries. Masson et Cie, Paris, 1955.
  2. ^ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9. 
  3. ^
  4. ^ 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. 
  5. ^ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0.