Abstract:

Objective: To investigate the clinical application value of combined molecular biology testing (GeneXpert MTB/RIF, PCR-TB-DNA, TB/NTM-PCR, fluorescent quantitative PCR, and DNA microarray technology) with bronchoalveolar lavage fluid (BALF) in the diagnosis of smear-negative pulmonary tuberculosis. Methods: A total of 150 patients with suspected pulmonary tuberculosis and negative smear results admitted to the Fourth People’s Hospital of Taiyuan from January 2024 to April 2025 were enrolled as study subjects. BALF specimens were collected and all underwent GeneXpert MTB/RIF, PCR-TB-DNA, TB/NTM-PCR, fluorescent quantitative PCR, and DNA microarray technology. Based on final clinical diagnosis results, the diagnostic value of BALF with different molecular biological testing as well as the combined five methods for smear-negative pulmonary tuberculosis patients was evaluated. Results: Among 150 patients, 108 cases were clinically diagnosed as pulmonary tuberculosis, 7 cases as non-tuberculous mycobacterial infection (NTM), and 35 cases as non-tuberculosis. Using the final diagnosis as the criterion, the sensitivities of GeneXpert MTB/RIF, PCR-TB-DNA, TB/NTM-PCR, fluorescent quantitative PCR, and DNA microarray technology were 66.7% (72/108), 62.9% (68/108), 54.6% (59/108), 59.3% (64/108) and 62.9% (68/108), respectively; the specificities were 100.0% (42/42), 97.6% (41/42), 97.6% (41/42), 97.6% (41/42) and 100.0% (42/42), respectively; and the areas under the receiver operating characteristic (ROC) curve (AUC) were 0.67, 0.6, 0.52, 0.56 and 0.62, respectively. The combined application of five molecular biological methods showed that the strategy combining GeneXpert MTB/RIF with fluorescent quantitative PCR demonstrated excellent diagnostic performance (sensitivity 92.5% (100/108), specificity 92.8% (39/42),AUC=0.85). Conclusion: The combined molecular biological testing using BALF specimens provides an effective laboratory protocol for the rapid early diagnosis of suspected pulmonary tuberculosis patients with negative sputum smear results, demonstrating comprehensive superiority in diagnostic efficacy over any single testing method, which is worthy of clinical promotion and application.

Key words: Bronchoalveolar lavage, Molecular diagnostic techniques, Mycobacterium tuberculosis, Diagnosis, differential