''Mycobacterium kansasii'' is a

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

in the ''

Mycobacterium ''Mycobacterium'' is a genus of over 190 species in the phylum Actinomycetota, assigned its own family, Mycobacteriaceae. This genus includes pathogens known to cause serious diseases in mammals, including tuberculosis ('' M. tuberculosis'') ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

. It is an environmental bacteria that causes

opportunistic infection An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immun ...

s in humans, and is the one of the leading mycobacterial causes of human disease after

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, ...

and

leprosy Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria '' Mycobacterium leprae'' or '' Mycobacterium lepromatosis''. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve d ...

Description

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

, nonmotile, moderately-long to long, and

acid-fast Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sam ...

rods.

Colony characteristics

It forms smooth to rough

colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

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 The Timpe and Runyon classification of nontuberculous mycobacteria based on the rate of growth, production of yellow pigment and whether this pigment was produced in the dark or only after exposure to light. It was introduced by Ernest Runyon in ...

) according to the

Runyon classification The Timpe and Runyon classification of nontuberculous mycobacteria based on the rate of growth, production of yellow pigment and whether this pigment was produced in the dark or only after exposure to light. It was introduced by Ernest Runyon i ...

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 β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...

on the surface and inside of colony.

Physiology

Its physiology is described as growth on Middlebrook 7H10 agar at 37

°C The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The d ...

within 7 days or more, resistant to

pyrazinamide Pyrazinamide is a medication used to treat tuberculosis. For active tuberculosis, it is often used with rifampicin, isoniazid, and either streptomycin or ethambutol. It is not generally recommended for the treatment of latent tuberculosis. I ...

and susceptible to

ethambutol Ethambutol (EMB, E) is a medication primarily used to treat tuberculosis. It is usually given in combination with other tuberculosis medications, such as isoniazid, rifampicin and pyrazinamide. It may also be used to treat ''Mycobacterium avi ...

Differential characteristics

It is closely related to the non-pathogenic, also slowly growing, nonpigmented, '' M. gastri''. Both species share an identical

16S rDNA 16 S ribosomal RNA (or 16 S rRNA) is the RNA component of the 30S subunit of a prokaryotic ribosome ( SSU rRNA). It binds to the Shine-Dalgarno sequence and provides most of the SSU structure. The genes coding for it are referred to as 16S ...

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 * ''Mycobacterium kansasii'' (former subtype I) * ''Mycobacterium persicum'' (former subtype II) * ''Mycobacterium pseudokansasii'' (former subtype III) * ''Mycobacterium ostraviense'' (former subtype IV) * ''Mycobacterium innocens'' (former subtype V) * ''Mycobacterium attenuatum'' (former subtype VI) * and ''Mycobacterium gastri''

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 The University of Kansas Medical Center, commonly referred to as KU Med or KUMC, is a medical campus for the University of Kansas. KU Med houses the university's schools of medicine, nursing, and health professions, with the primary health science ...

Pathogenesis

''M. kansasii'' may cause chronic human

pulmonary disease Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bron ...

resembling

. Extrapulmonary infections, such as

cervical lymphadenitis Cervical lymphadenopathy refers to lymphadenopathy of the cervical lymph nodes (the glands in the neck). The term ''lymphadenopathy'' strictly speaking refers to disease of the lymph nodes, though it is often used to describe the enlargement of the ...

in children,

cutaneous Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different d ...

and soft tissues infections, and musculoskeletal system involvement are uncommon. Rarely it causes disseminated disease in patients with severely impaired

cellular immunity Cell-mediated immunity or cellular immunity is an immune response that does not involve antibodies. Rather, cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines ...

(such as

organ transplants Organ transplantation is a medical procedure in which an organ is removed from one body and placed in the body of a recipient, to replace a damaged or missing organ. The donor and recipient may be at the same location, or organs may be transpor ...

AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ma ...

). Pre-existing lung disease such as silicosis is a risk factor. ''Mycobacterium kansasii'' occasionally involves the skin in a sporotrichoid pattern. It is unclear where people acquire the infection and person-to-person spread is not thought to occur.

Tap water Tap water (also known as faucet water, running water, or municipal water) is water supplied through a tap, a water dispenser valve. In many countries, tap water usually has the quality of drinking water. Tap water is commonly used for drinking, ...

is believed to be the major reservoir associated with human disease. Biosafety level 2 is indicated.

Type strain

First and most frequently isolated from human pulmonary secretions and

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classif ...

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

References

External links

*
Type strain of ''Mycobacterium kansasii'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q4044720 Acid-fast bacilli kansasii Bacteria described in 1955