To evaluate the diagnostic value of metagenomic nextgeneration sequencing (mNGS) in non-tuberculous Mycobacterial pulmonary disease (NTMPD) and to analyse its clinical characteristics.

Clinical data of 93 patients with suspected NTMPD admitted to our hospital from January 2020 to January 2024 were retrospectively reviewed. All patients underwent mycobacterium culture and mNGS testing. Using the final clinical diagnosis as the gold standard, the diagnostic performances of the two methods were compared. The mycobacterial species distribution, infection types, clinical manifestations, and prognosis of confirmed NTMPD patients were analysed.

Among the 93 suspected patients, 65 cases (69.89%) were definitively diagnosed with NTMPD. Compared with the confirmed diagnosis, the diagnostic accuracy of mycobacterium culture was 76.34%, with a Kappa value of 0.470 (P<0.05), indicating moderate agreement; the diagnostic accuracy of mNGS was 94.62%, with a Kappa value of 0.873 (P<0.05), indicating excellent agreement. Among the 65 confirmed patients, 43 cases (66.15%) had single NTM infection and 22 cases (33.85%) had mixed NTM infection, of which 11 cases had 2 species, 9 had 3 species, and 2 had 4 species. A total of 7 species were identified: Mycobacterium intracellulare in 29 cases (44.62%), Mycobacterium avium in 17 cases (26.15%), Mycobacterium abscessus in 14 cases (21.54%), Mycobacterium fortuitum in 10 cases (15.38%), Mycobacterium paraintracellulare in 9 cases (13.85%), Mycobacterium massiliense in 7 cases (10.77%), and Mycobacterium chubuense in 5 cases (7.69%). ROC curve analysis showed that the AUC for mycobacterium culture in diagnosing NTMPD was 0.607 (95%CI: 0.477~0.736, P=0.104), with a sensitivity of 78.46% and specificity of 74.42%; the AUC for mNGS was 0.923 (95% CI: 0.850~0.997, P<0.001), with a sensitivity of 95.38% and specificity of 92.85%. The difference in AUC between the two methods was statistically significant (Z=4.176, P<0.001). Of the 65 confirmed patients, 64 responded well to antimycobacterial treatment, while 1 patient, who had underlying comorbidities including COPD, cor pulmonale, and bronchiectasis, died of septic shock and multiple organ dysfunction syndrome.

mNGS demonstrates superior sensitivity and specificity over traditional mycobacterium culture in diagnosing NTMPD. It accurately identifies mycobacterial species and distinguishes mixed infections, offering high diagnostic efficacy and significant clinical utility.