Recurrent, disseminated Mycobacterium marinum infection caused by the same genotypically defined strain in an immunocompromised patient

An 81-year-old male with myasthenia gravis developed a cutaneous infection with Mycobacterium marinum, which apparently resolved following local heat therapy. Five months later, the patient developed new skin lesions and pancytopenia. M. marinum was isolated from his bone marrow. Pulsed-field gel electrophoresis was performed to determine if the skin and bone marrow isolates were clonally related. Digestion of the genomic DNA with the restriction enzymes SpeI and AseI yielded indistinguishable banding patterns. An epidemiologically unrelated control strain showed significant banding differences. The results suggest that the patient's recurrent, disseminated infection was due to recrudescence of his initial infection rather than reinfection by another strain.