Objective To explore the microbiological and clinical characteristics of extrapulmonary nontuberculous mycobacterial disease (ENTM).

Methods Laboratory extrapulmonary samples positive for NTM between Jan. 2017 and Dec. 2021 were retrospectively searched in Zhongshan Hospital, Fudan Univeristy. Thirty three confirmed ENTM cases were included. Demographic, microbiological, clinical characteristics, as well as treatment and prognosis were analyzed.

Results A total of 33 confirmed ENTM cases were included, average age was (49±16.3) years, 23 cases(69.7%) were female, one third of the patients were immunocompromised. Skin and soft tissue infection, bone and joint infection, and disseminated NTM disease were the most common types(57.6%, 18.2%, and 15.6%). Healthcare-associated infections accounted for 51.5% (17/33) of the cases. Mycobacterium abscessus complex (42.4%) in rapidly growing mycobacteria (RGM) was the most common causative species. Patients received combination therapy with an average of (3.5±0.8) drugs for 6.3 (4.3, 9.6) months. Most cases recovered (69.7%) or improved clinically (18.2%). Compared with RGM, infections with SGM were seen in older individuals (60.2±15.0 vs 42.6±14.0, P < 0.05) and were more often community acquired (83.3% vs 28.6%, P < 0.05).

Conclusions Skin and soft tissue infection is the most common type of ENTM, with Mycobacterium abscessus complex being the most important causative species. SGM infections affect older population and are more often community acquired. Treatment of ENTM is challenging and lacks standardized protocol, future researches are needed.