Aquarium granuloma (also known as fish tank granuloma and swimming pool granuloma) is a rare skin condition caused by a non-tubercular mycobacterium known as ''

Mycobacterium marinum ''Mycobacterium marinum'' is a slow growing mycobacterium (SGM) belonging to the genus ''Mycobacterium'' and the phylum Actinobacteria. The strain marinum was first identified by Aronson in 1926 and it is observed as a pathogenic mycobacterium. F ...

''. Skin infections with ''M. marinum'' in humans are relatively uncommon, and are usually acquired from contact with contaminated swimming pools, aquariums or infected fish.

Signs and symptoms

Aquarium granuloma presents as a slow-growing, inflamed red bump (nodule or plaque) at the site of infection. It is characterized by a painful, itchy skin lesion, and may become ulcerated or crusted. Skin changes usually appear roughly three weeks after the aquatic exposure.https://www.aocd.org/general/custom.asp?page=FishTankGranuloma If this condition is acquired from an aquarium, then often the dominant hand is affected. If this condition is acquired from a swimming pool, then symptoms can also develop on trauma-prone body zones, such as the elbows, knees, feet and tip of the nose.

Cause

For the infection to develop in humans, the two main factors required are exposure to contaminated water, and abrasion or injury to the skin. Hence, this infection is commonly seen in individuals who clean fish tanks, handle ornamental fish and work in wet fields.Pereira, C., Tauro, L. F., & Shetty, P. (2020). Aquarium granuloma: a diagnosis based on history. ''International Surgery Journal'', ''7''(6), 2036-2038. Aquatic systems with a high density of fish and warm waters appear to be conditions particularly favorable to this infectious agent, and increase the chances to contract fish tank granuloma. Poor water quality and various nutritional deficiencies are also possible contributing factors. Swimming pool granuloma can occur when there is inadequate chlorination of swimming pools.

Diagnosis

Aquarium granuloma is relatively nonspecific in clinical presentation. Therefore, more common skin conditions, like

cellulitis Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of ...

foreign body reaction A foreign body reaction (FBR) is a typical tissue response to a foreign body within biological tissue. It usually includes the formation of a foreign body granuloma. Tissue-encapsulation of an implant is an example, as is inflammation around a spli ...

skin cancer Skin cancers are cancers that arise from the skin. They are due to the development of abnormal cells that have the ability to invade or spread to other parts of the body. There are three main types of skin cancers: basal-cell skin cancer (BCC) ...

, and fungal or parasitic infections, are often explored first. Overall, diagnosis and treatment of this rare skin infection is often delayed because of a lack of suspicion. Lab tests for finding ''M. marinum'' include cultures where a swab or sample is taken and grown in the laboratory. Cultures of ''M. marinum'' are fairly difficult to grow, and results may take several weeks. The culture may be negative, even if there is an active infection. Treatment may still be considered even if the test results are negative, especially if the patient's history supports past fish or fish-tank exposure. In the absence of positive culture results, a skin or tissue biopsy may be a helpful test to render a microscopic diagnosis. Another technique that can be used to detect the bacteria is

Polymerase Chain Reaction The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) ...

(PCR). A biopsy sample itself is sufficient to detect the exact type of bacteria by means of PCR.

Prevention

* Avoid fresh or saltwater activities if there are open cuts, scrapes, or sores on the skin, especially in water where this bacterium is known to exist. * Wear heavy gloves (leather or heavy cotton) while cleaning or processing fish, especially fish with sharp spines that may cause cuts to the hands and skin. Wash hands thoroughly with soap and water after fish processing or use a waterless cleanser. * Wear waterproof gloves while cleaning home aquariums or fish tanks. Wash hands and forearms thoroughly with soap and running water after cleaning the tank, even if gloves were worn. * Ensure regular and adequate chlorination of swimming pools to kill any bacteria that may be present.

Treatment

Treatment involves the use of antibiotics. Since M. marinum has a high tendency for multi-drug resistance, treatment by one particular drug will not be effective. Often, up to six different antimicrobial regimes may be needed before the infection responds to a particular drug combination. This combination of antibiotics is based on the results of the culture and skin biopsy. The treatment can take up to several months. Surgery may also be needed to remove dead tissue if the lesions do not clear with antibiotics. This helps the wound to heal.

Epidemiology

''Mycobacterium'' ''marinum'' infection is not contagious; it is not spreading from person to person. It is also not transmitted in hospitals like other common bacteria.

References

External links

{{Gram-positive actinobacteria diseases Mycobacterium-related cutaneous conditions