Mycobacterium marinum
Cultural characteristics
Biochemical characters
Phylum Actinobacteria, Class Actinobacteria, Order Actinomycetales, Suborder Corynebacterineae, Family Mycobacteriaceae, Genus
Mycobacterium marinum Aronson 1926.

Synonyms (not valid): “Mycobacterium balnei”, “Mycobacterium platypoecilus”.
Closely related to
Mycobacterium ulcerans as by 16S rRNA gene and ITS sequences.
Acid-fast, moderate to long rods with frequent cross barring. Forms cords.
Colonies are smooth to rough on Lowenstein–Jensen medium and Middlebrook agar
after incubation for 7 or more days at 30 ºC. On primary isolation, growth is restricted
to the temperature range 25–35 ºC, but adaptation to 37 ºC may occur after several
subcultures. No growth at 42 or 45 ºC.
Photochromogenic (no pigmentation in the dark, but when exposed or grown in light,
colonies develop a brilliant yellow color). No growth on MacConkey agar without
crystal violet or in 5% NaCl media.
Isolated from diseased fish and aquaria; in humans, from lesions incurred in swimming pools or fish tanks. Resistant to
hydroxylamine (500 µg/ml), tiophene-2-carboxylic acid hydrazide (1 µg/ml), ethambutol (5 µg/ml), rifampicin (25 µg/ml) and isoniazid
(1 µg/ml) (variable).
M. ulcerans is found in tropical regions whereas M. marinum is common in temperate climates.
Opportunistic pathogen in humans, causing cutaneous granulomas (“swimming pool granuloma”), usually on elbows, fingers,
forearms, or wrists, but also can occur on feet, knees, and toes. Papules or nodules occur which may ulcerate.
Experimental infection: mice receiving a large inoculum intraperitoneally develop ulcerations on paws, scrotum, and tail; visceral
lesions and death sometimes occur. Following intravenous inoculation,lesions are limited to the tail. Footpad inoculations lead to
local swelling and ulceration.
Guinea pigs inoculated subcutaneously or by inhalation do not exhibit disease; intraperitoneal inoculation occasionally leads to
scrotal lesions.
Amphibians, fish, and reptiles have been found susceptible to fatal systemic infection when maintained at 30 ºC.
Isolated from a koi fish, a Guppy fish as well as an exotic fish in South Africa and an unidentified fish species, all showing skin
lesions and or ulcerations on the head.
  1. John G. Magee and Alan C. Ward 2012. Family III. Mycobacteriaceae Chester 1897, 63AL in Bergey’s Manual of Systematic
    Bacteriology, Volume Five The Actinobacteria, Part A, Michael Goodfellow & al. (editors), 312-375.
  2. Loredana Gabriela Popa, Mircea Ioan Popa 2009. Identificarea bacililor acido-rezistenti in: Tratat de microbiologie clinica, Dumitru
    Buiuc, Marian Negut, ed. a III-a, Editura Medicala, 881-890, ISBN (13) 978-973-39-0593-6.
  3. John F. Staropoli and John A. Branda. Cord Formation in a Clinical Isolate of Mycobacterium marinum. J Clin Microbiol. 2008 Aug;
    46(8): 2814–2816, doi: 10.1128/JCM.00197-08.
  4. Julian E, Roldan M, Sanchez-Chardi A, Astola O, Agusti G, Luquin M. Microscopic cords, a virulence-related characteristic of
    Mycobacterium tuberculosis, are also present in nonpathogenic mycobacteria. J Bacteriol. 2010;192(7):1751–1760. doi:10.1128
  5. Bojalil LF, Cerbon J, Trujillo A. Adansonian classification of mycobacteria. J Gen Microbiol 1962; 28:333-346.
  6. Tsukamura M, Yano I, Imaeda T. Mycobacterium fortuitum subspecies acetamidolyticum, a new subspecies of Mycobacterium
    fortuitum. Microbiol Immunol 1986; 30:97-110.
  7. Stanford JL, Gunthorpe WJ. A study of some fast-growing scotochromogenic mycobacteria including species descriptions of
    Mycobacterium gilvum (new species) and Mycobacterium duvalii (new species). Br J Exp Pathol 1971; 52:627-637.
  8. Gcebe, N., Michel, A.L. & Hlokwe, T.M. Non-tuberculous Mycobacterium species causing mycobacteriosis in farmed aquatic
    animals of South Africa. BMC Microbiol 18, 32 (2018).
Positive results for acid phosphatase, nicotinamidase, pyrazinamidase, Tween 80 hydrolysis, and urea hydrolysis.
Can utilize as sole carbon source in the presence of ammonia: succinate (most strains), propionate and pyruvate.

Negative results for arylsulfatase (3 days; positive at 10 days), catalase (inactivated at 68 ºC), alpha-esterase, beta-galactosidase,
indole production,  neutral red test, nitrate reduction, and niacin production.
No utilization of citrate, malate, fumarate and benzoate. No iron uptake.

Variable results for semiquantitative catalase test and tellurite reduction (9 days).
(c) Costin Stoica
Culture media
Biochemical tests
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