The clinical suspicion of active tuberculosis with sample submitted for NGS platform in Huashan Hospital was prospectively enrolled in the period from March 1, 2017 to September 1, 2017. All the cases were followed up for final clinical diagnosis. The submission samples (4 cases of bronchial lavage fluid, 18 cases of cerebrospinal fluid, pleural effusion in 4 cases, 3 cases of pus, ascites, liver tissue in 2 cases, 1 case of synovial fluid) were all sequenced on the BGISEQ-100 platform, and the final result was obtained by comparing the pathogenic sequences to the pathogen database. A positive result for NGS was defined as detection of the single matching sequence of Mycobacterium tuberculosis complex. At least one of tuberculosis culture, pathologically diagnosed tuberculosis infection, Xpert MTB/RIF positive and tuberculosis nucleic acid test is positive for the diagnosis of definite active tuberculosis infection. There are other etiological evidence or clinical exclusion of active tuberculosis infection as non-tuberculosis infection. Then we analyze the sensitivity and specificity of NGS in the diagnosis of tuberculosis.

Among them, 9 cases was definite TB cases, including Xpert MTB/RIF positive in 6 cases, pathological diagnosis in 4 cases, 3 cases of culture positive, tuberculosis nucleic acid PCR positive in 1 case; clinical diagnosis of active tuberculosis in 10 cases, non-tuberculosis infection in 15 cases. Among the definite and clinically diagnosed cases, 11 cases of Mycobacterium tuberculosis complex were detected by NGS. The sensitivity and specificity were 57.9% (11/19) and 100.0% (15/15) respectively. In confirmed cases, the NGS sensitivity was 66.7% (6/9). Among the 31 specimens sent in parallel for Xpert MTB/RIF and NGS, the clinical diagnosis was the gold standard, with a specificity of 100.0% (15/15) and a sensitivity of 37.5% (6/16) and 50.0% (8/16), respectively, with no significant difference (McNemar test, P=0.727).

The second-generation sequencing can detect Mycobacterium tuberculosis complex in multiple samples more rapidly. Its sensitivity and specificity are comparable to those of Xpert MTB/RIF and can be used as a diagnostic test for the early diagnosis of active TB.