Summary about Disease
Mycobacterium marinum infection, also known as "fish tank granuloma" or "swimming pool granuloma," is a chronic granulomatous skin infection caused by the bacterium Mycobacterium marinum. This bacterium is commonly found in fresh and saltwater environments, including fish tanks, swimming pools, and natural bodies of water. The infection typically occurs when the bacteria enter the skin through abrasions, cuts, or scrapes.
Symptoms
The most common symptom is the development of a slowly progressive skin lesion, usually a nodule or papule, at the site of entry. These lesions often appear on the hands, fingers, elbows, or knees. The lesions can be single or multiple and may ulcerate. Other symptoms may include:
Local pain or tenderness
Swollen lymph nodes near the affected area
In rare cases, spread to deeper tissues, joints, or bones (especially in immunocompromised individuals).
Causes
Mycobacterium marinum infection is caused by direct contact with the bacterium *Mycobacterium marinum*, which is present in contaminated water sources like:
Fish tanks
Swimming pools
Natural bodies of water (lakes, rivers, oceans)
Handling infected fish or marine animals.
Trauma to skin exposed to contaminated water.
Medicine Used
Treatment typically involves a course of antibiotics. Commonly used antibiotics include:
Tetracyclines (e.g., doxycycline, minocycline)
Macrolides (e.g., clarithromycin, azithromycin)
Fluoroquinolones (e.g., ciprofloxacin, levofloxacin)
Rifampin
Ethambutol Combination therapy with two or more antibiotics is sometimes used, especially in more severe or resistant cases. Treatment duration is typically several weeks to months.
Is Communicable
Mycobacterium marinum infection is *not* generally considered communicable from person to person. It is acquired through environmental exposure to the bacterium.
Precautions
Wear gloves when cleaning fish tanks or handling aquatic animals.
Thoroughly clean and disinfect any wounds or abrasions, especially after exposure to water.
Avoid swimming in or handling water from sources that appear dirty or contaminated.
Maintain proper hygiene when cleaning fish tanks and swimming pools.
Immunocompromised individuals should be particularly cautious when handling aquatic environments.
How long does an outbreak last?
Without treatment, lesions can persist for months to years. With appropriate antibiotic treatment, resolution usually occurs within several weeks to months. The duration depends on the severity and extent of the infection, the specific antibiotics used, and the individual's immune response.
How is it diagnosed?
Diagnosis typically involves:
Clinical examination: Assessing the appearance and location of the skin lesions.
Culture: A sample from the lesion is cultured to identify Mycobacterium marinum. This is the most definitive diagnostic test.
Biopsy: A skin biopsy may be performed to examine the tissue under a microscope. Granulomas are often seen.
Polymerase Chain Reaction (PCR): A PCR test can identify the presence of Mycobacterium marinum DNA in a sample.
Acid-fast staining: Staining of biopsy samples to identify acid-fast bacteria.
Timeline of Symptoms
Incubation period: 2-4 weeks (time between exposure and onset of symptoms).
Initial lesion: Small papule or nodule appears at the site of entry.
Progression: Lesion slowly enlarges over weeks to months.
Ulceration: The lesion may ulcerate.
Spread: In some cases, the infection may spread to deeper tissues or lymph nodes, usually over several weeks to months if left untreated.
Important Considerations
Early diagnosis and treatment are crucial to prevent complications and minimize the duration of the infection.
Treatment requires a prolonged course of antibiotics, and adherence to the treatment regimen is essential.
Drug resistance can occur, so monitoring treatment response is important.
Immunocompromised individuals may be at higher risk for more severe or disseminated infections.
Atypical presentations of the disease are possible.
Consult a healthcare professional for proper diagnosis and management.