Swimming pool granuloma
A swimming pool granuloma is a long-term (chronic) skin infection caused by the bacteria Mycobacterium marinum.
Aquarium granuloma; Fish tank granuloma
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 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 may spread up the limb, but most often they stay a simple skin sore.
Exams and Tests
Tests to diagnose swimming pool granuloma include:
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 a combination of antibiotics. Surgery may also be needed.
Swimming pool granulomas can usually be cured with antibiotics. However, you may have scarring.
Occasionally, joint or bone infections occur. The disease may be longer or more complicated in patients whose immune system is not working properly.
When to Contact a Medical Professional
Call your health care provider if you develop reddish bumps on your skin which do not clear with home treatment.
Avoid contact with contaminated water. Wear gloves or wash thoroughly when cleaning aquariums.
Brown-Elliott BA, Wallace RJ Jr. Infections due to nontuberculous mycobacteria other than Mycobacterium avium-intracellulare. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Disease. 7th ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 253.
Holland S. The nontuberculous mycobacteria. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 346.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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