Skin infection with Mycobacterium marinum from a tropical fish tank.

Opportunist acid-fast bacilli sometimes cause progressive indolent infections of the skin, producing nodules, granulomatous lesions, abscesses, or ulcers. Some of these mycobacteria prefer temperatures lower than 370C for growth, and minor trauma or devitalized tissue probably aid their entry and establishment. One such organism, Mycobacterium marinum (balnei), was identified as the cause of epidemic cutaneous lesions among swimming-pool bathers in Sweden (Linell and Norden, 1954) and later in Britain (Morgan and Blowers, 1964; Waddington, 1967). It is pathogenic for fish, and sporadic human infection attributed to this source was first reported by Swift and Cohen (1962). We describe a further case of a patient with spreading cutaneous lesions caused by infection with Myco. marinum from a tropical fish tank.