Atypical Mycobacterial Infections of the Upper Extremity: Becoming More Atypical?

Background: Atypical mycobacterial infections are uncommon and characterized by a chronic, indolent course before diagnosis. Historically, these infections are associated with marine-related injury and/or immune dysfunction. Our institution has successfully diagnosed and treated an increasing number of these infections. The objective of this study is to review our experience with these rare infections and verify the developing trends encountered. Methods: A retrospective review was performed for patients with positive nontuberculous mycobacterial cultures of the upper extremity from 2000 to 2013. Patient demographics, source of transmission, symptom duration, mycobacterial species, operative and antibiotic treatments, and outcomes were recorded. Results: Thirty-four patients were identified. The mean symptomatic period before diagnosis was 9 months (range, 1-60 months). Fourteen patients had identifiable causes of immune dysfunction while the rest appeared immune competent. Patients were infected by Mycobacterium marinum (n = 14), Mycobacterium abscessus (n = 8), Mycobacterium fortuitum (n = 7), and other less common species (n = 5). Although most patients had unidentifiable causes of infection (n = 15), some could correlate infection to marine injury, lacerations, insect bites, animal bites, and tattoos. All patients received operative intervention including debridement. Antibiotics were given for a mean duration of 5 months. Ninety-seven percent had complete resolution of disease. Conclusions: Although M. marinum infections make up the majority of infections at our institution, we report a higher total incidence of nonmarinum infections. These infections are occurring in seemingly healthy individuals with no history of exposure with marine water. Successful treatment relies on having a heightened clinical awareness and adequate diagnosis.