Non-tuberculous mycobacterial skin and soft tissue infections in the Northern Territory, Australia, 1989-2021

Abstract

Background: A previous review demonstrated that the majority of NTM infections in the Northern Territory (NT) are pulmonary in nature [1], however skin and soft tissue (SST) are likely the next most common sites of disease. The current epidemiology of NTM SST infections across the NT is not known. We aimed to establish the current and historical incidence rates, and the organisms involved. Methods: All NTM cases reported to the Centre for Disease Control in Darwin from 1989-2021 were retrospectively reviewed. Results: 226 NTM notifications were reviewed. 73 (32%) cases were SST infections. The incidence of SST cases increased over the study period. Female cases were more common (p=0·002). Disease occurred across a wide age range (1-85 years). Only 16% of cases occurred in Aboriginal individuals which may reflect immunological factors requiring further investigation. Many cases had no clear provocation, but localised skin trauma was the most common risk factor. The most common organism identified was M. fortuitum (41%). Diagnosis was often delayed, with a median time to diagnosis of 69 days (IQR=31-149). Most cases (60%) underwent surgical intervention with adjunctive anti-mycobacterial medical therapy. Conclusion: NTM SST incidence rates increased over the study period. NTM SST infections are a rare but important differential diagnosis for non-healing cutaneous wounds.

Keywords

• Non-tuberculous mycobacteria
• Skin
• Soft tissue
• Cutaneous
• Northern Territory
• Australia