Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
Mycobacterium marinum (formerly M. balnei) is a free-living bacterium, which causes opportunistic infections in humans. M. marinum sometimes causes a rare disease known as aquarium granuloma, which typically affects individuals who work with fish or keep home aquariums.
Although Aronson isolated this mycobacterium in 1926 from a fish, it was not until 1951 that it was found to be the cause of human disease by Linell and Norden. Large outbreaks of infection due to this atypical mycobacterium have been described in association with swimming. Infections related to swimming pools have now drastically fallen due to the improvements in the construction and maintenance of these facilities.
The first case of M. marinum infection associated with a fish-tank (‘fish-tank granuloma) was reported in 1962 by Swift and Cohen. M. marinum infection may be an occupational hazard for certain professions such as pet shop workers, but most infections occur in fish fanciers who keep an aquarium at home. Although infection may be caused by direct injury from the fish fins or bites, most are acquired during the handling of the aquariums such as cleaning or changing the water. Indirect infection has also been described related to a child’s bathing utensils that had been used to clean a fish tank. Due to an increased awareness of the disease and improved isolation methods, more and more cases are being recognized and reported worldwide.
Skin lesions produced by M. marinum infections may be single but are often multiple. Typically, clusters of superficial nodules or papules are described. An erythematous plaque has also been reported. The lesions may be painful or painless and may become fluctuant. The lesions typically occur on the elbows, knees and feet in swimming pool-related cases, and on the hands and fingers in aquarium owners. The inhibition of growth of M. marinum at 37°C is related to its ability to infect the cooler parts of the body especially the extremities. Lesions appear after an incubation period of about 2–4 weeks, and after 3–5 weeks they are typically 1–2.5 cm in diameter. Although most infections follow an indolent course, the disease can progress rapidly. Rarely, disseminated infection and bacteremia has been reported in immunocompromised patients.
Diagnosis is frequently delayed, probably due to the rarity of the infection and a failure to elicit the usual history of aquatic exposure. Common misdiagnoses include fungal and parasitic infection, cellulitis, skin tuberculosis, rheumatoid arthritis, foreign body reaction, and skin tumor. A high index of suspicion and a detailed history are important in establishing the diagnosis of M. marinum infection. Long delays in diagnosis can result in severe, destructive infection. On primary isolation M. marinum grows on LJ slants at 30-33°C in 7–21 days. Unlike M. tuberculosis, most strains of M. marinum will not grow at the usual incubation temperature of 37°C. Colonies are cream in color and turn yellow when exposed to light (photochromogenic). M. marinum, once cultured, is readily identified by using conventional mycobacterial characterization methods. It grows relatively quickly (1 to 2 weeks) and is easily recognized as a result of its photochromogenicity. Infections due to M. marinum can usually be treated with antimycobacterial drugs. Sometimes, cultures are negative but the diagnosis is still made based on physical signs supported by typical histological findings, as M. marinum is a very common atypical mycobacterium causing skin infection (70). Various DNA-based techniques have been used to classify mycobacteria. All such studies have demonstrated a high taxonomic affiliation between M. ulcerans and M. marinum. Some M. marinum isolates have been shown to harbor the insertion sequence, IS2404, however, no M. marinum strains contain IS2606. M. ulcerans isolates are positive for both insertion sequences. It was previously thought that IS2404 and IS2606 were specific to M. ulcerans but recent evidence has proved this true only for IS2606.
- 1. M. marinum isolates 
- Susceptible: Rifampin, Rifabutin, Ethambutol, Clarithromycin, Sulfonamides, and Trimethoprim sulfamethoxazole
- Intermediately susceptible: Streptomycin, Doxycycline, and Minocycline
- Resistant: Isoniazid and Pyrazinamide
- NOTE: Two active agents for 1 to 2 months after resolution of symptoms, typically 3 to 4 months in total
- 2. skin and soft tissue infections
- Preferred regimen (1): Clarithromycin AND Ethambutol
- Preferred regimen (2): Ethambutol AND Rifampin
- Alternative regimen: Azithromycin replaces Clarithromycin
- 3. osteomyelitis or deep structure infection
- Preferred regimen (1): Clarithromycin AND Ethambutol AND Rifampin
- ↑ Aronson JD (October 1926). "Spontaneous tuberculosis in salt water fish". J Infect Dis. 39 (4): 314–320. doi:10.1093/infdis/39.4.315.
- ↑ Cox R, Mirkin SM (May 1997). "Characteristic enrichment of DNA repeats in different genomes". Proc. Natl. Acad. Sci. U.S.A. 94 (10): 5237–42. doi:10.1073/pnas.94.10.5237. PMC 24662. PMID 9144221.
- ↑ Wolinsky E (July 1992). "Mycobacterial diseases other than tuberculosis". Clin. Infect. Dis. 15 (1): 1–10. doi:10.1093/clinids/15.1.1. PMID 1617048.
- ↑ Linell F, Norden A (1954). "Mycobacterium balnei, a new acid-fast bacillus occurring in swimming pools and capable of producing skin lesions in humans". Acta Tuberc Scand Suppl. 33: 1–84. PMID 13188762.
- ↑ Tautz D, Schlötterer (December 1994). "Simple sequences". Curr. Opin. Genet. Dev. 4 (6): 832–7. doi:10.1016/0959-437X(94)90067-1. PMID 7888752.
- ↑ Huminer D, Pitlik SD, Block C, Kaufman L, Amit S, Rosenfeld JB (June 1986). "Aquarium-borne Mycobacterium marinum skin infection. Report of a case and review of the literature". Arch Dermatol. 122 (6): 698–703. doi:10.1001/archderm.1986.01660180104026. PMID 3487289.
- ↑ Hurst LC, Amadio PC, Badalamente MA, Ellstein JL, Dattwyler RJ (May 1987). "Mycobacterium marinum infections of the hand". J Hand Surg Am. 12 (3): 428–35. doi:10.1016/s0363-5023(87)80018-7. PMID 3584892.
- ↑ "Girl, 13, faces having her hand amputated after scratching it in fish tank". Daily Mail. London. 13 June 2011.
- ↑ King AJ, Fairley JA, Rasmussen JE (March 1983). "Disseminated cutaneous Mycobacterium marinum infection". Arch Dermatol. 119 (3): 268–70. doi:10.1001/archderm.1983.01650270086024. PMID 6824363.
- ↑ Huminer D, Dux S, Samra Z; et al. (September 1993). "Mycobacterium simiae infection in Israeli patients with AIDS". Clin. Infect. Dis. 17 (3): 508–9. doi:10.1093/clinids/17.3.508. PMID 8218698.
- ↑ Wendt JR, Lamm RC, Altman DI, Cruz HG, Achauer BM (September 1986). "An unusually aggressive Mycobacterium marinum hand infection". J Hand Surg Am. 11 (5): 753–5. doi:10.1016/s0363-5023(86)80029-6. PMID 3760509.
- ↑ Parenti DM, Symington JS, Keiser J, Simon GL (October 1995). "Mycobacterium kansasii bacteremia in patients infected with human immunodeficiency virus". Clin. Infect. Dis. 21 (4): 1001–3. doi:10.1093/clinids/21.4.1001. PMID 8645786.
- ↑ Collins CH, Grange JM, Noble WC, Yates MD (April 1985). "Mycobacterium marinum infections in man". J Hyg (Lond). 94 (2): 135–49. doi:10.1017/s0022172400061349. PMC 2129405. PMID 3886781.
- ↑ Kox LF, Kuijper S, Kolk AH (December 1995). "Early diagnosis of tuberculous meningitis by polymerase chain reaction". Neurology. 45 (12): 2228–32. doi:10.1212/wnl.45.12.2228. PMID 8848198.
- ↑ Rogall T, Wolters J, Flohr T, Böttger EC (October 1990). "Towards a phylogeny and definition of species at the molecular level within the genus Mycobacterium". Int. J. Syst. Bacteriol. 40 (4): 323–30. doi:10.1099/00207713-40-4-323. PMID 2275850.
- ↑ Yip MJ, Porter JL, Fyfe JA; et al. (March 2007). "Evolution of Mycobacterium ulcerans and other mycolactone-producing mycobacteria from a common Mycobacterium marinum progenitor". J. Bacteriol. 189 (5): 2021–9. doi:10.1128/JB.01442-06. PMC 1855710. PMID 17172337.
- ↑ Griffith, David E.; Aksamit, Timothy; Brown-Elliott, Barbara A.; Catanzaro, Antonino; Daley, Charles; Gordin, Fred; Holland, Steven M.; Horsburgh, Robert; Huitt, Gwen; Iademarco, Michael F.; Iseman, Michael; Olivier, Kenneth; Ruoss, Stephen; von Reyn, C. Fordham; Wallace, Richard J.; Winthrop, Kevin; ATS Mycobacterial Diseases Subcommittee; American Thoracic Society; Infectious Disease Society of America (2007-02-15). "An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases". American Journal of Respiratory and Critical Care Medicine. 175 (4): 367–416. doi:10.1164/rccm.200604-571ST. ISSN 1073-449X. PMID 17277290.
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- 80. Kox, L. F. F., S. Kuijper, and A. H. J. Kolk. 1995. Early diagnosis of tuberculous meningitis by polymerase chain reaction. Neurol 45:2228-2232.
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- 82. Yip, M.J., Porter, J.L., Fyfe, J.A.M., Lavender, C.J., Portaels, F., Rhodes, M., Kator, H., Colorni, A., Jenkin., G.A., Stinear, T. 2007. Evolution of Mycobacterium ulcerans and Other Mycolactone-Producing Mycobacteria from a Common Mycobacterium marinum Progenitor. J Bacteriol. 189(5):2021-2029
From: Master Thesis presented at the Master Program in Medical and Pharmaceutical Research Vrije Universiteit Brussel, Brussels, Belgium. Genotyping Mycobacterium ulcerans, M. marinum and M. liflandi using mycobacterial interspersed repetitive units, and gyrase restriction enzyme analysis. Pieter Stragier. 2003 – 2004 Template:SIB