A Case of Mycobacterium marinum Skin Infection

A 47-year-old man, who kept, tropical fish in his home, visited our hospital on January 1998, because of multiple subcutaneous nodular lesions with tenderness that had developed on his left hand and forearm following an injury to his left link fingertip. A skin biopsy from a nodule of his left forearm revealed a granulomatous inflammation consisting mainly of epithelioid cells and lymphocytes with abscess formation in the mid dermis and the subcutaneous tissue. Although a direct acid-fast smear showed no pathogens, an acid-fast photochromogen was isolated from Kudo medium incubated at 28°C for two weeks. The isolate was identified as Mycobacterium marinum according to both DNA-DNA hybridization and various bacteriological identification tests for atypical mycobacteriosis. After treatment with oral minocycline (200mg/day) for 9 weeks followed by sparfloxacin (200mg/day) for 5 weeks, the nodular lesions cured with atrophic scars.