Swimming pool granuloma
A swimming pool granuloma is a long-term (chronic) skin infection. It is caused by the bacteria Mycobacterium marinum.
Aquarium granuloma; Fish tank granuloma
Causes, incidence, and risk factors
A swimming pool granuloma occurs when water containing Mycobacterium marinum bacteria enters a break in the skin. Signs of a skin infection appear about 2 - 3 weeks later.
Risks include exposure to swimming pools, salt water aquariums, or ocean fish.
The main symptom is a reddish bump (papule) that slowly grows into a purplish and painful nodule.
The elbows, fingers, and back of the hands are the most common body parts affected. The knees and legs are less commonly affected.
The nodules may break down and leave an open sore. Sometimes, they spread up the limb. Most often they stay a simple skin sore.
Signs and tests
Tests to diagnose swimming pool granuloma include:
Skin test to check for tuberculosis infection, which may look similar
Skin biopsy and culture
- X-ray or other imaging tests for infection that has spread to the joint or bone
Antibiotics are used to treat this infection. They are chosen based on the results of the culture and skin biopsy.
You may need several months of treatment with more than one antibiotic. Surgery may also be needed.
Swimming pool granulomas can usually be cured with antibiotics. However, you may have scarring.
Tendon, joint or bone infections sometimes occur. The disease may be harder to treat in patients whose immune system is not working well.
Calling your health care provider
Call your health care provider if you develop reddish bumps on your skin that do not clear with home treatment.
Wash hands and arms thoroughly after cleaning aquariums. Or, wear rubber gloves when cleaning.
Bhambri S, Bhambri A, Del Rosso JQ. Atypical mycobacterial cutaneous infections. Dermatol Clin. 2009;27:63-73.
Brown-Elliott BA, Wallace RJ Jr. Infections due to nontuberculous mycobacteria other than Mycobacterium avium-intracellulare. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Disease. 7th ed. Philadelphia, PA: Elsevier Saunders; 2009:chap 253.
Last reviewed 1/22/2013 by Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Stephanie Slon, and Nissi Wang.
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