Clinical value of quantitative PCR in diagnosis of suspected mycobacterial pulmonary infections

Due to the difficulty in clinically distinguishing pulmonary infections caused by Mycobacterium tuberculosis (MTB) and Non-tuberculous mycobacteria (NTM), the study utilizes quantitative PCR (qPCR) technology to simultaneously detect MTB, Mycobacterium abscessus complex (MABC), Mycobacterium avium complex (MAC), and Mycobacterium kansasii(M. kansasii),to explore its clinical value in diagnosing of patients suspected mycobacterial pulmonary infections. A retrospective analysis was conducted on a cohort of 102 patients suspected of mycobacterial pulmonary infections. Samples of sputum and bronchoalveolar lavage fluid were extracted for testing with acid-fast staining (AFS), qPCR, and metagenomic next-generation sequencing (mNGS). Assess the diagnostic performance of AFS, qPCR, and mNGS for four types of mycobacteria based on comprehensive pulmonary tuberculosis (PTB) CRS composite criteria, non-tuberculous mycobacteria (NTM) diagnostic and treatment guidelines, as well as clinical observations. The sensitivity, specificity, positive predictive value, negative predictive value, and AUC of qPCR for mycobacteria (MTB, MABC, MAC) were 90.00% (76.33–97.20), 100.00% (94.22–100.00), 100.00% (99.90–100.00), 93.93% (85.95–97.51), and 0.950 (0.888–0.983), respectively. For mNGS, the corresponding estimates were 87.50% (73.19–95.81), 96.77% (88.82–99.60), 94.59%(81.66–98.56),92.30% (84.07–96.46), and 0.921(0.851–0.965), respectively. The research showed that the sensitivity and specificity of qPCR and mNGS method for detecting mycobacteria are higher than AFS; and there was no statistical difference in the diagnostic performance for mycobacteria between qPCR and mNGS, but qPCR was superior to mNGS in specific values. Compared with AFS, qPCR has higher sensitivity and specificity but statistical significance needs to be assessed with larger sample sizes for mycobacteria identification. In this regard, qPCR and mNGS demonstrate exhibit similar performance. However, qPCR is less expensive and more convenient for pathogen detection, which make it a promising lower-cost alternative diagnostic method for patients suspected of mycobacterial pulmonary infections in resource-limited settings.