Abstract:

Objective: To evaluate the diagnostic value of nanopore sequencing on bronchoalveolar lavage fluid (BALF) for pulmonary tuberculosis(PTB). Methods: A prospective study was conducted. BALF samples were collected from 577 suspected PTB patients who were admitted to the Fourth People’s Hospital of Nanning, Guangxi Zhuang Autonomous Region, from October 2021 to August 2023 and met the inclusion criteria. The samples were subjected to acid-fast bacilli staining smear microscopy (AFB), mycobacterial solid culture, MTB-DNA, GeneXpert MTB/RIF (hereinafter referred to as “Xpert”), and nanopore sequencing. Positive detection rates of the five detection methods were calculated. With the final clinical diagnosis as the reference standard, the diagnostic efficacies of single-method and combined detection method were comparatively analyzed. Results: Among the 577 suspected PTB patients, 473 were diagnosed with PTB, and 104 were diagnosed with non-tuberculous diseases. The positive rates of AFB, mycobacterial solid culture, MTB-DNA, Xpert, and nanopore sequencing were 19.06% (110 cases), 28.60% (165 cases), 25.13% (145 cases), 26.86% (155 cases), and 57.19% (330 cases) respectively. Among them, nanopore sequencing could independently detect 144 positive patients. The sensitivities of nanopore sequencing, mycobacterial solid culture, Xpert, MTB-DNA, AFB, and traditional etiological methods(combined the four methods except nanopore sequencing) were 68.71% (325/473), 30.44% (144/473), 32.35% (153/473), 30.02% (142/473), 20.08% (95/473), and 46.30% (219/473) respectively; the specificities were 95.19% (99/104), 79.81% (83/104), 98.08% (102/104), 97.12% (101/104), 85.58% (89/104), and 75.96% (79/104) respectively; the Kappa values were 0.416, 0.048, 0.139, 0.122, 0.024, and 0.120 respectively; and the AUC values were 0.820, 0.551, 0.652, 0.636, 0.528, and 0.611 respectively. The combined diagnosis strategies showed that sensitivities of nanopore sequencing combined with each one of mycobacterial solid culture, Xpert, MTB-DNA, and AFB were 72.94% (345/473), 69.98% (331/473), 71.04% (336/473), and 70.61% (334/473) respectively; and the specificities were 76.92% (80/104), 93.27% (97/104), 92.31% (96/104), and 82.69% (86/104) respectively; the Kappa values were 0.359, 0.420, 0.427, and 0.367 respectively; and the AUC values were 0.751, 0.817, 0.818, and 0.768 respectively. Conclusion: Compared with the other four methods, nanopore sequencing technology has the best detection efficacy for PTB, and it combined with MTB-DNA test has the best diagnostic efficacy, which shows its significant advantages in diagnosing PTB and is expected to become an important tool for PTB diagnosis.

Key words: Tuberculosis, pulmonary, Bronchoalveolar lavage fluid, Nanotechnology, Diagnosis, Comparative study