A chronic skin infection caused by the bacteria Mycobacterium marinum .
Causes, incidence, and risk factors
A swimming pool granuloma results when water containing an infectious organism, Mycobacterium marinum , enters a break in the skin. A localized infection called a granuloma results after about 3 weeks. The lesions appear as reddish bumps ( papules ) that slowly enlarge into purplish nodules . The elbows, fingers, back of the hands, and knees are the most common sites affected. The nodules may break down and ulcerate leaving an open sore or spread up the limb.
Signs and tests
Though swimming pool granulomas have a characteristic appearance, a skin biopsy and culture is usually necessary to confirm the diagnosis. A PPD tuberculin skin test will usually be positive as well.
Treatment
Oral antibiotics are needed to clear this infection. Choices include minocycline, Bactrim, clarithromycin, and levofloxacin. Several months of treatment are often required.
Expectations (prognosis)
Swimming pool granulomas can usually be treated completely with antibiotics.
Complications
Occasionally, joint or bone infections occur. Patients with defective immune systems may also have longer or more complicated cases.
Calling your health care provider
Call your health care provider if you develop reddish bumps on your skin which do not clear with home treatment.
Prevention
Avoid contact with contaminated water. Wear gloves or was thoroughly when cleaning aquariums.