Diagnostic value of nucleic acid matrix-assisted laser desorption ionization-time of flight mass spectrometry in sputum smear-negative patients with nontuberculous Mycobacterial pulmonary disease / 中华临床感染病杂志

ABSTRACT

Objective:To investigate the diagnostic value of nucleic acid matrix-assisted laser desorption ionization-time of flight mass spectrometry（MALDI-TOF MS）in sputum smear-negative patients with nontuberculous Mycobacterial（NTM）pulmonary disease.Methods:Clinical data of 123 patients suspected of NTM pulmonary disease admitted in Public Health Clinical Center Affiliated to Shandong University between July 2022 and November 2023 were retrospectively analyzed. Bronchoalveolar lavage fluid（BALF）specimens were collected for MALDI-TOF MS assay and MGIT 960 culture. The diagnostic efficacy of MALDI-TOF MS for NTM pulmonary disease in patients with negative sputum smears for acid-fast bacilli was evaluated with receiver operating characteristic（ROC）curve. Statistical analysis was performed using SPSS 26.0 software and MedCalc statistical software.Results:Diagnosis of NTM pulmonary disease was finally confirmed in 66 out of the 123 suspected patients. It took 8 to 24 h for MALDI-TOF MS to identify NTM species and resistance. By MALDI-TOF MS，72 NTM strains were identified，with the Mycobacterium avium complex being the most prevalent（34 strains，47.22%），followed by the Mycobacterium abscessus complex（13 strains，18.06%）；resistance to macrolides was detected in 6 cases，while no resistance to aminoglycosides was found. It took 9 to 45 days for BALF MGIT 960 culture to identify NTM，and took 7 to 15 days for NTM typing and drug sensitivity testing. By BALF MGIT 960 culture，28 NTM strains were identified；and 1 case was found to be resistant to macrolides. Using confirmed diagnosis as the gold standard，MALDI-TOF MS demonstrated higher sensitivity，negative predictive value，and agreement rate compared to MGIT 960 culture（84.85% vs. 42.42%，81.13% vs. 56.32%，80.49% vs. 62.60%， χ2=25.667，8.998，9.664， P<0.05 or <0.01）. The area under ROC curve（AUC）for MALDI-TOF MS was significantly higher than that of MGIT 960 culture（0.801 vs. 0.642， Z=3.300， P=0.001）. Conclusion:Compared to MGIT 960 culture，MALDI-TOF MS exhibits superior diagnostic efficiency in detecting NTM pulmonary disease in patients with acid-fast bacilli smear-negative sputum，with advantage of rapidly identifying NTM species and resistance.