Abstract:

Objective: To evaluate the early diagnostic efficacy of the fluorescence quantitative PCR (DiagMed qPCR, abbreviated as “qPCR”) in detecting sputum smear-negative pulmonary tuberculosis using bronchoalveolar lavage fluid. Methods: A prospective study was conducted, enrolling consecutive suspected pulmonary tuberculosis patients with sputum smear-negative results who met the inclusion criteria and were treated at the Second People's Hospital of Weifang from July to November 2024 as the study subjects. The bronchoalveolar lavage fluid samples submitted by the research subjects were subjected to smear acid fast bacteria staining microscopy, MGIT 960 liquid culture (referred to as “liquid culture”), GeneXpert MTB/RIF (referred to as “Xpert”), and qPCR detection. The results of liquid culture and clinical comprehensive diagnosis were used as reference standards to evaluate the diagnostic value of qPCR technology in detecting bronchoalveolar lavage fluid for sputum smear-negative pulmonary tuberculosis. Results: Finally, 168 study subjects were included. The positive rate of acid fast bacteria staining in bronchoalveolar lavage fluid smear microscopy was 19.05% (32/168), the positive rate of liquid culture was 32.74% (55/168), the positive rate of Xpert detection was 37.50% (63/168), and the positive rate of qPCR detection was 42.26% (71/168). There was no statistically significant difference in the positive rate of qPCR detection compared to Xpert detection and liquid culture (χ²=3.251, P=0.071; χ²=0.836, P=0.361). Using liquid culture results as a reference standard, the sensitivity and specificity of qPCR detection were 96.36% (53/55) and 84.07% (95/113), respectively; the sensitivity and specificity of Xpert detection were 94.55% (52/55) and 90.27% (102/113), respectively. Based on clinical diagnostic results, the sensitivity and specificity of qPCR detection were 63.06% (70/111) and 98.25% (56/57), respectively; the sensitivity and specificity of Xpert detection were 56.76% (63/111) and 100.00% (57/57), respectively; the sensitivity of qPCR detection was significantly higher than that of Xpert detection, and the difference was statistically significant (χ²=65.298, P<0.05). Conclusion: qPCR detection of bronchoalveolar lavage fluid showed good efficacy in the diagnosis of sputum smear-negative pulmonary tuberculosis, providing an important means for early diagnosis of pulmonary tuberculosis in primary medical institutions using molecular biology technology.

Key words: Mycobacterium tuberculosis, Polymerase chain reaction, Diagnosis, differential, Bronchoalveolar lavage fluid, Evaluation studies