Evaluation of nucleic acid-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for rapid identification of Mycobacterium tuberculosis and drug resistance in patients with retreatment tuberculosis.

OBJECTIVE

This study aimed to evaluate the value of nucleic acid-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in identifying mycobacterial species and detecting drug resistance in patients with retreatment pulmonary tuberculosis (TB).

METHODS

The clinical data of 100 patients with retreatment pulmonary TB treated at Wenzhou Central Hospital between 1 June 2022 and 31 December 2023 were retrospectively collected and analyzed. Respiratory secretions were examined using BACTEC MGIT 960 Rapid Liquid Culture (MGIT 960 culture), drug-sensitive gene chip strain identification and nucleic acid-based MALDI-TOF MS assay (MassARRAY® system). Unlike traditional protein-based MALDI-TOF MS, this nucleic acid-based approach detects specific gene mutations associated with drug resistance. The results of the MGIT 960 culture and drug resistance testing served as the benchmark for evaluating the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the MALDI-TOF MS assay.

RESULTS

For Mycobacterium tuberculosis (MTB) detection, compared with the MGIT 960 culture, the nucleic acid-based MALDI-TOF MS assay demonstrated a sensitivity of 97.01% (65/67), specificity of 63.64% (21/33), PPV of 84.42% (65/77) and NPV of 91.30% (21/23), with a concordance of 86.00% and a kappa value of 0.619. The difference in detection results between the two methods was statistically significant (χ2 = 15.625, p < 0.001). For drug-resistance detection in the 34 MTB-positive cases with both methods, concordance with MGIT 960 was 97% for rifampicin (97% sensitivity, 100% specificity) and 88% for isoniazid (86% sensitivity, 100% specificity), with overall κ = 0.83 across first- and second-line drugs.

CONCLUSION

The nucleic acid-based MALDI-TOF MS assay demonstrates promising performance in rapidly identifying MTB and detecting drug resistance, serving as a valuable complementary tool for rapid clinical diagnosis and personalized medication guidance in patients with retreatment TB. The detection of non-tuberculous mycobacteria requires further validation with larger sample sizes.