We report three cases of mycobacterium marinum infection, characterized by the long duration before a proper diagnosis was made. Mycobacterium marinum is a so-called atypical non-tuberculous mycobacterium, found in salt and fresh water, occasionally infecting humans. Most of the infections involve the fingers and the hand, after exposure to contaminated water. It is commonly called fish tank infection.
The clinical picture can be very different: from a small cutaneous lesion to deep-seated infections of the tendon sheet or joint.
Special transport and culture techniques are required for proper diagnosis. Besides surgical treatment of chronic skin lesions and deep infections, prolonged treatment with appropriate antibiotics is required.