What is Mycobacterium marinum?
Mycobacterium marinum (M. marinum) is a slow-growing atypical mycobacterium that is commonly found in bodies of fresh or saltwater in many parts of the world. Skin infections with Mycobacterium marinum in humans are relatively uncommon and are usually acquired from contact with aquariums or fish. Most infections occur following skin exposure to the bacteria through a small cut or skin scrape. The first signs of infection with M. marinum include a reddish or tan skin bump called a granuloma. Less commonly, a string or batch of the small reddish bumps crop up on the exposed body area in a classic pattern called sporotrichotic lymphangitis.
It is somewhat rare to acquire this infection from well-maintained swimming pools because of protection afforded by proper chlorination. Mycobacterium marinum does not typically grow at normal body temperature, which is why it remains localized to the cooler skin surface. Overall, diagnosis and treatment of this unusual skin infection is often delayed because of a lack of suspicion for this atypical mycobacterium versus more common bacteria like Staphylococcus.
What are other names for Mycobacterium marinum infections?
Some synonyms for Mycobacterium marinum skin infections include tropical fish granuloma, fish tank granuloma and fish tank granuloma.
How common is Mycobacterium marinum?
Although rare, infections can occur worldwide, most commonly in individuals with occupational and recreational exposure to fresh or saltwater. In the United States, infections caused by M. marinum are rare. The infection is very rare in children and is typically a disease of adults.