Mycobacterium marinum

Chau Nguyen, M.D.

A small, raised, erythematous lesion developed on the dorsum of the hand of a 35-year-old man who worked in a pet shop. Over a period of three months, there was progressive spreading of nodular lesions from his hand to just above his elbow. There was no epitrochlear or axillary adenopathy. The patient did not have fever or other symptoms. His duties included cleaning fish tanks daily, which he did without wearing protective gloves. Needle aspiration of a nodule recovered thick, purulent fluid that was positive for acid-fast bacilli, identified on culture as Mycobacterium marinum. The patient was treated successfully with a four-month regimen of rifampin and ethambutol.

M. marinum infection is an occupational hazard for aquarium cleaners, fishermen, and seafood handlers. Since growth of the organism requires a low temperature (between 24° and 32°C), infection is usually limited to the skin, with the hands, elbows, and feet most commonly affected. Dissemination of the infection, even among immunocompromised patients, is rare.

Chau Nguyen, M.D.

Memorial University of Newfoundland, St. John's, NF A1B 3V6, Canada