The Timpe and Runyon classification of nontuberculous

mycobacteria ''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'') and ...

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 1959. On these bases, the nontuberculous mycobacteria are divided into four groups:

Slowly growing Mycobacteria

The first three groups are classified as "Slowly growing Mycobacteria".

Runyon I: Photochromogens

Runyon I organisms (

photochromogen Mycobacteria that form colonies clearly visible to the naked eye in more than 7 days on subculture are termed slow growers. They can cause disease in humans. List of slowly growing Mycobacteria Nonchromogenic Rough * Mycobacterium africanum * ...

s) are slow growing, and produce a yellow-orange pigment when exposed to light. The group includes ''

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

'', '' Mycobacterium marinum'', ''

Mycobacterium asiaticum ''Mycobacterium asiaticum'' is a slowly growing photochromogenic mycobacterium first isolated from monkeys in 1965. ''M. asiaticum'' can, but rarely, causes human pulmonary disease. Description Microscopy *Gram-positive, nonmotile, acid-fast, ...

'', and ''

Mycobacterium simiae ''Mycobacterium simiae'' is a species of ''Mycobacterium''.As per Runyon's classification it is classified as a photochromogen Mycobacteria that form colonies clearly visible to the naked eye in more than 7 days on subculture are termed slow gro ...

''. ''

Mycobacterium szulgai ''Mycobacterium szulgai'' is a species of ''Mycobacterium''. It is a scotochromogen Scotochromogenic bacteria develop pigment in the dark. Runyon Group II nontuberculous mycobacteria ''Mycobacterium'' is a genus of over 190 species in the ...

'' is a photochromogen when grown at 24 degrees, and a scotochromogen at 37 degrees. In contrast, Runyon classifications III through IV are considered ''nonphotochromogens'', in that exposure to light does not make them produce pigment which they would not develop in dark growing conditions.

Runyon II: Scotochromogens

Runyon II organisms ( scotochromogens) are slow-growing and produce a yellow-orange pigment regardless of whether they are grown in the dark or the light. The group includes ''

Mycobacterium gordonae ''Mycobacterium gordonae'' is a species of ''Mycobacterium'' named for Ruth E. Gordon. It is a species of the phylum Actinomycetota (Gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), b ...

'' and '' Mycobacterium scrofulaceum'', among others. ''

'' is a scotochromogen when grown at 37 degrees, as mentioned above.

Runyon III: Nonchromogens

Runyon III organisms (nonchromogens) are slow-growing and never produce pigment, regardless of culture conditions. The group includes ''

Mycobacterium avium ''Mycobacterium avium ''complex is a group of mycobacteria comprising ''Mycobacterium intracellulare'' and ''Mycobacterium avium'' that are commonly grouped because they infect humans together; this group, in turn, is part of the group of nontu ...

'' and ''

Mycobacterium intracellulare ''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'') and ...

'' (together known as the MAC complex), ''

Mycobacterium tuberculosis ''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on it ...

'', '' Mycobacterium ulcerans'' and numerous other organisms.

Runyon IV: Rapid Growers

Runyon IV organisms are rapid growing for mycobacteria (colonies in 5 days). They do not produce pigment. '' Mycobacterium fortuitum'', '' Mycobacterium peregrinum'', ''

Mycobacterium abscessus ''Mycobacteroides abscessus'' (formerly ''Mycobacterium abscessus'') is a species of rapidly growing, multidrug-resistant, nontuberculous mycobacteria that is a common soil and water contaminant. Although ''M. abscessus'' most commonly causes ch ...

'', ''

Mycobacterium chelonae ''Mycobacteroides chelonae'' (formerly ''Mycobacterium chelonae'') is a species of bacteria from the phylum Actinomycetota belonging to the genus '' Mycobacteroides''. ''Mycobacteroides chelonae'' is a rapidly growing mycobacterium that is found ...

'', '' Mycobacterium thermoresistibile''. Some rapidly growing mycobacteria are considered "late-pigmenting".

References

*R {{Mycobacterium-stub