Mycobacterium smegmatis
Cultural characteristics
Biochemical characters
Phylum Actinobacteria, Class Actinobacteria, Order Actinomycetales, Suborder Corynebacterineae, Family Mycobacteriaceae, Genus
Mycobacterium smegmatis (Trevisan 1889) Lehmann and Neumann 1899.

Possible old synonym: "Smegma Bacillus" Alvarez and Tavel (1885).
Members of the
Mycobacterium smegmatis group 2 and 3 were moved to Mycobacterium goodii and Mycobacterium wolinskyi species,
Acid-fast rods, 3-5 μm long, occasionally curved with branching or Y-shaped cells.
Cells are sometimes swollen and may appear as deeper staining beaded or ovoid
forms. In cultures older than 5-7 days non-acid-fast forms begin to develop. No cord
Colonies that appear on Löwenstein–Jensen medium in 2-4 days are usually rough,
wrinkled or coarsely folded, and nonpigmented or creamy white. Smooth, glistening,
butyrous colonies are seen, but pigmentation is rare, though it may be seen in older
cultures. On Middlebrook agar, the rough colonial form appears smooth textured over
a rugose, but non-corded, granular colony; the smooth form is domed, smooth
textured, and granular. Feshly isolated  strains may show smooth colonies, whereas
strains  maintained in the laboratory may show rough colonies. Temperature range
for growth is 25-45 ºC. Can grow on media supplemented with 5% (w/v) NaCl. No
growth on MacConkey agar.
Isolated from smegma. Resistant to tiophene-2-carboxylic acid hydrazide (1 µg/ml) and rifampicin (25 µg/ml).
Susceptible to hydroxylamine (500 µg/ml).
It i usually associated with secretions of the normal genitalia and with soft lesions following accidental or surgical trauma.
Not pathogenic for chickens, guinea pigs, hamsters, or mice, but pathogenic cultures may be obtained from the spleens of guinea
pigs and/or mice.
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    No. 5, International Conference on Atypical Mycobacteria (Sep. - Oct., 1981), pp. 841-861.
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    Friedmannii. J Gen Microbiol, 58 (1), 99-106 Sep 1969.
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    et al. Mycobacterium wolinskyi sp. nov. and Mycobacterium goodii sp. nov., two new rapidly growing species related to
    Mycobacterium smegmatis and associated with human wound infections: a cooperative study from the International Working
    Group on Mycobacterial Taxonomy. Int J Syst Bacteriol 1999; 49:1493-1511.
Positive results for semiquantitative catalase test, beta-galactosidase, iron uptake, nitrate reduction, nicotinamidase, pyrazinamidase,
tellurite reduction, Tween hydrolysis and urea hydrolysis.
Can utilize benzoate, citrate, mannitol, glucose, acetate, pyruvate, succinate, malate, fumarate, malonate, mucate, propanol, butanol,  
propionate, arabinose, xylose, rhamnose, trehalose, inositol, sorbitol as sole carbon source.

Negative results for arylsulfatase (3 days), acid phosphatase, alpha-esterase (most strains), thermostable catalase (68 ºC), and
hippurate hydrolysis.
(c) Costin Stoica
Culture media
Biochemical tests
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