Evaluation of different methods in diagnosis of spinal tuberculosis infection

Abstract Background and purposes:Tuberculosis (TB) is the most lethal infectious disease worldwide. About 24.6% of tuberculosis cases are extrapulmonary TB which commonly affects spine. Spinal tuberculosis (STB) is difficult to diagnose. This study aims to evaluate the diagnostic performance of MGIT-960 culture, T-SPOT.TB, Xpert MTB/RIF, and Metagenomic Next-Generation Sequencing (mNGS) in detecting STB. Methods: 126 patients presumed to have STB were tested by 4 methods. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated considering the clinical diagnosis as the reference. Results: 126 patients were enrolled in this study, 41 with STB and 85 with non-STB infection. In the STB group, the sensitivity, specificity, PPV and NPV of MGIT-960 culture were 29.3% (12/41), 100% (85/85), 100% (12/12), and 74.6% (85/114).The sensitivity of T-SPOT.TB was 92.7% (38/41), and the specificity, PPV and NPV were 82.4% (70/85), 58.5% (31/53) and 95.9% (70/73). The sensitivity, specificity, PPV and NPV of Xpert MTB/RIF were 53.7% (22/41), 100% (85/85), 100% (22/22) and 81.7% (85/104). The sensitivity, specificity, PPV and NPV of mNGS were 39.0% (16/41), 98.8% (84/85), 94.1% (16/17) and 77.1% (84/109).The sensitivity, specificity, PPV and NPV of the mNGS+Xpert MTB/RIF group were 73.2% (30/41), 100% (85/85), 96.8% (30/31) and 72.0% (85/118). The sensitivity, specificity, PPV and NPV of the mNGS+T-spot group were 97.6% (40/41), 100% (85/85), 67.9% (38/56) and 75.9% (85/113).The sensitivity, specificity, PPV and NPV of the T-spot+Xpert MTB/RIF group were 95.1% (39/41), 100% (85/85), 72.2% (39/54) and 81.0% (85/105). Conclusions: Among the 4 detection methods, T-SPOT.TB is the most effective technique for diagnosing STB, but Xpert MTB/RIF is more reliable and can detect RIF resistance. mNGS can be used to identify pathogens in patients with spinal infections, and pathogens identified by mNGS appear to be more meaningful in guiding clinical management in patients in the non-STB group. The combination of Xpert MTB/RIF and mNGS can improve the early diagnosis rate and detection of drug resistance of STB, reduce the diagnosis cycle, and provide early targeted anti-tuberculosis treatment.