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Mycobacterium marinum infection in Adult
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Mycobacterium marinum infection in Adult

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Contributors: Tara Mahar MD, Art Papier MD
Other Resources UpToDate PubMed


Mycobacterium marinum, the causative agent of fish tank or swimming pool granuloma, is an atypical mycobacterial skin infection often contracted from contaminated fish tanks, swimming pools, and, occasionally, ocean or lake water. Minor trauma is a predisposing factor. Aquarium enthusiasts are usually not aware of the risk of infection. Because of occupational risks (eg, fisherman), men are more commonly affected than women. The typical skin lesion consists of a pustule or nodule and develops on the exposed extremity 2-3 weeks after exposure. Constitutional symptoms are rare and fever, if present, is typically low-grade. The disease is usually self-limited, and lesions tend to heal over a period of 1-2 years if left untreated.

Patients with AIDS, organ transplant recipients, and patients on chronic steroids may occasionally develop disseminated infections to the skin, bone marrow, and joints, leading to synovitis and arthritis.

Related topics: Mycobacterium avium-intracellulare, Mycobacterium kansasii, Mycobacterium fortuitum, Mycobacterium chelonae, Mycobacterium scrofulaceum, Mycobacterium tuberculosis, and Atypical mycobacterial infections


A31.1 – Cutaneous mycobacterial infection

58869008 – Mycobacterium marinum

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Differential Diagnosis & Pitfalls

Immunocompromised Patients:
  • Are more susceptible to the deep fungal, bacterial, and atypical mycobacterial infections listed above.
  • Bacillary angiomatosis can be seen in human immunodeficiency (HIV) / AIDS-infected patients with low CD4 counts.
  • Kaposi sarcoma is a consideration in this population as well.

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Last Updated: 04/12/2019
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Mycobacterium marinum infection in Adult
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Mycobacterium marinum infection : Lymphadenopathy, Lymphangitic, Skin ulcer, Smooth nodule, Fish tank exposure
Clinical image of Mycobacterium marinum infection
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