[Application value of metagenomic next-generation sequencing (mNGS) in the diagnosis of different types of tuberculosis].

Objective: To investigate the diagnostic value of metagenomic next generation sequencing(mNGS)for different types of tuberculosis(TB). Methods: A retrospective analysis was performed on suspected TB patients admitted to Shanghai Pulmonary Hospital from January 1, 2019 to December 31, 2019. The patients underwent mNGS test, acid-fast staining smear, Mycobacterium tuberculosis (MTB) culture and Xpert MTB/RIF(Xpert). A total of 205 TB suspects were finally included, including 120 males and 85 females, with a median age of 34 (16, 70) years. There were 165 cases of TB, including 92 males and 73 females, with a median age of 30 (12, 67) years. There were 40 non-TB patients, 28 males and 12 females, with a median age of 44.6 (24, 78) years, including 28 cases of infectious diseases and 12 cases of malignant tumors. With the final diagnosis as the reference standard, the diagnostic efficiency of mNGS in different types of tuberculosis (including pulmonary tuberculosis and extrapulmonary tuberculosis) and differences in diagnostic sensitivities between mNGS and other detection methods were calculated, respectively. P<0.05 was considered to be statistically different. Results: With clinical diagnosis as the reference standard, the sensitivity of mNGS to diagnose TB in this study was 60% (99/165, 95%CI: 0.53-0.67), and the specificity was 100% (40/40, 95%CI 0.90-1.00). The positive predictive value was 100% (99/99, 95%CI: 0.95-1.00), and the negative predictive value was 37.74% (40/106, 95%CI: 0.29-0.48). The sensitivity of mNGS in TB was 60% (99/165), higher than that of smear (10.9%, 18/165), Xpert(43.64%, 72/165) and culture (23.03%, 38/165). All the differences were statistically significant (P=0.00). The sensitivity of mNGS in pulmonary TB was 59%(59/100), which was significantly higher than that of smear (15%, 15/100) and culture (26%, 26/100), all P<0.001, but the difference was not statistically significant compared with Xpert (52%,52/100, P=0.09). In the extrapulmonary tuberculosis (EPTB), the sensitivity of mNGS was 61.54% (40/65), higher than that of acid fast staining(4.62%,3/65), Xpert (30.77%, 20/65)and culture (18.45%, 12/65). All the differences were statistically significant (all P<0.001). Conclusion: The mNGS was rapid and efficient in detection of MTB, and was superior to other traditional diagnostic methods for TB, especially for EPTB.