Abstract:

Objective To evaluate the clinical utility of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technology for identification of Mycobacterium tuberculosis and detection of associated drug-resistance genes, so as to provide technical suport for precision diagnosis of tuberculosis (TB). Methods Clinical data were collected from tuberculosis patients treated in Anhui Provincial Chest Hospital between November 2020 and May 2023. All patients underwent smear microscopy, mycobacterial growth indicator tube (MGIT) 960 culture and drug susceptibility testing (DST), Xpert MTB/RIF assay, and MALDI-TOF MS. MGIT 960 culture and DST results were used as the reference standard to evaluate the performance of MALDI-TOF MS for Mycobacterium tuberculosis identification and drug-resistance detection. Results The detection rate of Mycobacterium tuberculosis was 94.70% (125/132) by MALDI-TOF MS, 84.09% (111/132) by Xpert MTB/RIF, 67.42% (89/132) by MGIT 960, and 29.55% (39/132) by smear microscopy. The difference was significant (Q=172.87, P<0.001). The positive detection rate for rifampicin resistance was 53.03% (70/132) by MALDI-TOF MS, 45.45% (60/132) by Xpert MTB/RIF, and 44.70% (59/132) by MGIT 960 (Q=9.920, P=0.004). MALDI-TOF MS demonstrated the highest consistency for rifampicin resistance, which showed almost perfect agreement (Kappa=0.879, P<0.001), followed by high agreement with the results for fluoroquinolones and isoniazid (Kappa=0.698 and 0.667, both P<0.001). The consistency in clofazimine detection was relatively poor, showing moderate agreement (Kappa=0.476, P<0.001). Conclusion MALDI-TOF MS is worthy of recommendation in specialized hospitals, because this technique is highly sensitive and reliable for molecular diagnosis and drug-resistance screening of TB.

Key words: Mycobacterium tuberculosis, Mass spectrometry, Drug resistance, Sensitivity, Specificity