血浆结核分枝杆菌游离DNA检测对结核病的诊断价值

目的探讨血浆结核分枝杆菌游离DNA(cfDNA)检测对结核病(TB)诊断的临床应用价值。方法选取临床细菌学确诊结核病患者118例作为研究组,另选取同期非结核其他肺部疾病患者61例作为对照组。采用实时荧光定量PCR(Q-PCR)技术检测研究对象血浆中的结核分枝杆菌cfDNA,绘制ROC曲线分析其对结核病的诊断价值。并应用T-SPOT.TB检测、Xpert MTB/RIF (Xpert)检测对入组对象进行验证性诊断,采用配对四格表χ~2检验比较结核分枝杆菌cfDNA检测与T-SPOT.TB、Xpert检测在结核病诊断中的差异。结果结核分枝杆菌cfDNA检测诊断结核病的ROC曲线下面积(AUG)为:0.884,最佳诊断阈值(cut-off值)为38.69。T-SPOT.TB、Xpert、结核分枝杆菌cfDNA检测诊断结核病的灵敏性和特异性分别为:81.36%和40.98%、61.01%和96.72%、79.70%和95.10%。另外,结核分枝杆菌cfDNA检测对肺结核组(PTB)或肺外结核组(EPTB)患者的阳性检出率均高于Xpert检测(P<0.05),但与T-SPOT.TB检测相比差异均无统计学意义(P>0.05)。结论通过Q-PCR技术可以在结核病患者血浆中检测到结核分枝杆菌cfDNA,能够显著提高结核病的阳性检出率,并且有望成为肺外结核病快速诊断的新靶标。

Diagnostic value of plasma Mycobacterium tuberculosis cell-free DNA detection for tuberculosis

Objective To evaluate the clinical diagnostic value of plasma Mycobacterium tuberculosis cell-free DNA(MTB cfDNA) detection for tuberculosis(TB). Methods A total of 118 patients with bacteriological confirmed TB and 61 patients with other non-TB pulmonary diseases were included in this study. Their plasma MTB cfDNA were detected by real-time fluorescence quantitative PCR(Q-PCR), and ROC curve was generated to analyze the diagnostic efficacy of MTB cfDNA assay for TB. Then, the results of MTB cfDNA assay was compared with T-SPOT.TB assay and Xpert MTB/RIF(Xpert) assay through chi-square test. Results Area under the curve(AUC) and the cut-off value of MTB cfDNA detection for diagnosis of TB were 0.884 and 38.69, respectively. The sensitivity and specificity of T-SPOT.TB, Xpert, and MTB cfDNA assay were 81.36% and 40.98%, 61.01% and 96.72%, 79.70% and 95.10%, separately. In addition, the positive rate of MTB cfDNA assay for patients with pulmonary tuberculosis(PTB) or extrapulmonary tuberculosis(EPTB) was higher than Xpert assay(P<0.05), but there was no significant difference between MTB cfDNA assay and T-SPOT.TB assay(P>0.05). Conclusion This study verified that the detection of MTB cfDNA in plasma by Q-PCR is feasible and it can substantially improve the diagnostic sensitivity of TB. In addition, MTB cfDNA is expected to become a new target for the rapid diagnosis of EPTB.