3种分子检测方法对肺结核的诊断价值比较

Comparison of three molecular detection methods in the diagnosis of pulmonary tuberculosis

目的通过大样本评价DNA-TB、SAT-TB和Xpert 3种分子检测方法在支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中对肺结核的诊断价值,为临床医生选择检测方法学时提供依据。方法回顾性分析2016年7月至2021年9月在杭州市胸科医院就诊的8929名患者病历资料,所有BALF样本均行涂片、培养、DNA-TB、SAT-TB和Xpert检测,以培养为金标准,并根据涂片结果评估各检测方法的诊断性能。部分阳性结核菌株进行利福平表型药敏检测,以评估Xpert对利福平耐药的诊断性能。结果涂片的敏感性显著低于3种分子检测(P<0.05)。Xpert(90.3%)检测结核的敏感性高于DNA-TB(88.3%)和SAT-TB(84.3%)(P<0.05)。涂片阴性组3种分子检测(77.6%~85.1%)的敏感性显著低于涂片阳性组(均>95.0%)。涂片阴性组Xpert(85.1%)的敏感性显著高于DNA-TB(81.9%)和SAT-TB(77.6%)(P<0.05)。参考表型药敏,Xpert检测利福平耐药性的敏感性、特异性、阳性预测值和阴性预测值为89.7%、96.9%、77.1%和98.8%。结论Xpert检测BALF样本具有更高的敏感性、周转时间短、能同时检测利福平耐药、操作简单、对实验室要求低等优点。与DNA-TB和SAT-TB检测相比,在涂片阴性的BALF样本中采用Xpert检测对无痰、少痰或乏菌结核患者更有价值,在临床值得推广。

Objective To evaluate the diagnostic value of three molecular detection methods,including DNA-TB,simultaneous amplification and testing for Mycobacterium tuberculosis(SAT-TB)and Xpert,on pulmonary tuberculosis by a large number of bronchoalveolar lavage fluid(BALF)samples,and provide the basis for clinicians to select the diagnostic method of pulmonary tuberculosis.Methods The medical records of 8929 patients visited our hospital during July 2016 and September 2021 were retrospectively analyzed.All the BALF samples were tested by smear,culture,DNA-TB,SAT-TB and Xpert.With culture as the gold standard,the diagnostic performance of each detection method was evaluated based on the smear results.Some strains with positive Mycobacterium tuberculosis were tested for the phenotypic susceptibility of rifampicin to evaluate the diagnostic performance of Xpert for rifampicin resistance.Results The sensitivity of smear was significantly lower than that of the three molecular detection methods(P<0.05).The sensitivity of Xpert(90.3%)to detect tuberculosis was higher than that of DNA-TB(88.3%)and SAT-TB(84.3%)(P<0.05).The sensitivity of the three molecular detection methods(77.6%-85.1%)in the smear-negative group was significantly lower than that in the smear-positive group(all>95.0%).The sensitivity of Xpert(85.1%)in the smear-negative group was significantly higher than that of DNA-TB(81.9%)and SAT-TB(77.6%)(P<0.05).With reference to phenotypic susceptibility,the sensitivity,specificity,positive predictive value and negative predictive value of Xpert in detecting rifampicin resistance were 89.7%,96.9%,77.1%and 98.8%,respectively.Conclusion Xpert has the advantages of higher sensitivity,short turnaround time,simultaneous detection of rifampicin resistance,simple operation and low laboratory requirements in detecting BALF samples.Compared with DNA-TB and SAT-TB,the use of Xpert in smear-negative BALF samples may be more valuable for the pulmonary tuberculosis patients with little sputum or low bacterial load,and is worth promoting in clinical practice.