关键词: 结核, 肺, 聚合酶链反应, 临床实验室技术, 敏感性与特异性, 对比研究

Abstract:

Objective: To compare the diagnostic efficacy of the novel PCR-fluorescent probe method (DiagMed qPCR) with smear microscopy, liquid culture, and real-time fluorescent PCR in the detection of pulmonary tuberculosis. Methods: A total of 238 sputum samples from suspected pulmonary tuberculosis patients at Wuhan Pulmonary Hospital from March 20, 2021, to June 1, 2021, were consecutively enrolled. Taking clinical comprehensive diagnosis results as the reference standard, the diagnostic performance of smear microscopy, liquid culture, real-time fluorescent PCR, and DiagMed qPCR was evaluated and compared. Meanwhile, with the results of liquid culture and species identification as references, the correlation coefficient between the threshold cycle number (Ct) and bacterial load in samples from the two nucleic acid testing methods were assessed and compared. Results: Among the 238 patients, 167 cases were diagnosed with pulmonary TB, 1 case with nontuberculous mycobacterial disease, and 70 cases with pulmonary infections caused by fungi, viruses, and other non-tuberculous conditions based on clinical comprehensive diagnosis. Taking the clinical comprehensive diagnosis as the reference, the sensitivities of smear microscopy, liquid culture, real-time fluorescent PCR, and DiagMed qPCR for diagnosing pulmonary tuberculosis were 45.51% (76/167), 47.31% (79/167), 58.68% (98/167), and 58.68% (98/167), respectively; the specificities were 100.00% (71/71), 100.00% (71/71), 98.59% (70/71), and 98.59% (70/71), respectively; the AUC (%) values were 72.75%, 78.74%, 81.14%, and 82.24%, respectively. DiagMed qPCR and real-time fluorescence PCR showed the same positive detection rate for pulmonary TB (58.68%). The correlation coefficient R² between the Ct value of DiagMed qPCR and sputum bacterial content was higher than that of real-time fluorescent PCR assay (smear bacterial quantity grade: 0.213 vs. 0.187; culture-positive growth time: 0.293 vs. 0.290). Conclusion: In the detection of tuberculosis, both the DiagMed qPCR method and the real-time fluorescent PCR assay exhibit high sensitivity and specificity. However, the former demonstrates a stronger negative correlation between Ct values and bacterial load, which can improve detection efficiency.

Key words: Tuberculosis, pulmonary, Polymerase chain reaction, Clinical laboratory techniques, Sensitivity and specificity, Comparative study