交叉引物恒温扩增技术在初诊疑似肺结核患者诊断中的应用价值

目的: 评价交叉引物恒温扩增(cross-priming amplification,CPA)技术在初诊疑似肺结核患者诊断中的应用价值。方法: 选取2020年1月至2021年5月深圳市龙华区慢性病防治中心就诊的初诊疑似肺结核患者2408例作为研究对象。收集患者痰液标本分别采用萋-尼抗酸染色(acid-fast stain,AFS)法、BACTEC MGIT 960(简称“MGIT 960”)液体培养法及CPA技术对治疗前痰液标本进行结核分枝杆菌(Mycobacterium tuberculosis,MTB)检测,以MGIT 960液体培养法为参照标准,评价CPA诊断效能。结果: AFS法、MGIT 960液体培养法及CPA技术MTB阳性检出率分别为8.89%(214/2408)、27.99%(674/2408)及15.49%(373/2408),不同方法检测阳性率比较差异有统计学意义(χ²=314.619,P=0.000),其中MGIT 960液体培养法明显高于CPA技术和AFS法,而CPA技术高于AFS法,差异均有统计学意义(χ²=110.572、 292.158、 49.046,P值均=0.000)。以MGIT 960液体培养结果为参照标准,CPA检测MTB的敏感度、特异度、阳性预测值、阴性预测值及符合率分别为52.37%(353/674)、98.85%(1714/1734)、94.64%(353/373)、84.23%(1714/2035)及85.84%(2067/2408),而AFS法分别为31.45%(212/674)、99.88%(1732/1734)、99.07%(212/214)、78.94%(1732/2194)及80.73%(1944/2408),其中CPA技术的敏感度52.37%(95%CI:47.21%~59.64%)]明显高于AFS法31.45%(95%CI:26.87%~35.72%)],差异有统计学意义(χ²=108.290, P=0.000)。CPA技术与MGIT 960液体培养法检测结果一致性较好(Kappa=0.592),而与AFS法一致性较差(Kappa=0.395)。涂阳培阴率为0.08%(2/2408),培养污染率为5.40%(130/2408),而CPA检测无效例数为0。结论: 初诊疑似肺结核分枝杆菌感染CPA技术阳性检出率和敏感度明显高于AFS法,且一致性好于AFS法,同时操作简单、快速、经济及无污染,对肺结核早期诊断具有应用价值。

Evaluation of the potential of cross-priming amplification for the diagnosis of Mycobacterium tuberculosis infection

Objective: To evaluate the potential of cross-priming amplification (CPA) in the diagnosis of patients newly diagnosed with suspected pulmonary tuberculosis. Methods: Of 2408 new cases of suspected pulmonary tuberculosis presenting at Longhua District Chronic Disease Control Center in Shenzhen City from January, 2020 to May, 2021 were enrolled in the study. Sputum samples were collected and sputum smears (Ziehl-Neelsen acid-fast stain (AFS) method), BACTEC MGIT 960 (MGIT 960) liquid culture and CPA analysis were performed to detect Mycobacterium tuberculosis (MTB), MGIT 960 liquid culture being used as the gold standard to evaluate the diagnostic efficacy of CPA. Results: The MTB detection rate by AFS, MGIT 960 liquid culture and CPA was 8.89% (214/2408), 27.99% (674/2408) and 15.49% (373/2408), respectively. The difference in the detection rates of the three methods was statistically significant (χ²=314.619, P=0.000), with that of MGIT 960 liquid culture being significantly higher than both CPA and AFS, and that of CPA being higher than that of AFS (χ²=110.572, 292.158, 49.046, P=0.000). Using MGIT 960 liquid culture as the gold standard, the sensitivity, specificity, positive predictive value, negative predictive value and coincidence rate of CPA in detecting MTB were 52.37% (353/674), 98.85% (1714/1734), 94.64% (353/373), 84.23% (1714/2035) and 85.84% (2067/2408), respectively, while that of the AFS method was 31.45% (212/674), 99.88% (1732/1734), 99.07% (212/214), 78.94% (1732/2194) and 80.73% (1944/2408), respectively. The sensitivity of CPA (52.37%; 95%CI: 47.21%-59.64%) was significantly higher than that of AFS (31.45%; 95%CI: 26.87%-35.72%;χ²=108.290, P=0.000). Results of CPA were in good agreement with MGIT 960 liquid culture (Kappa=0.592), but AFS results showed poor agreement (Kappa=0.395). The smear-positive/culture-negative rate was 0.08% (2/2408), and the culture contamination rate was 5.40% (130/2408). All CPA detection results were valid. Conclusion: The positive detection rate and sensitivity of CPA for diagnosing cases of suspected MTB infection was significantly higher than that of AFS, and showed better consistency. The CPA technique is simple, rapid, economical and free of contamination, making it of promising value in the early diagnosis of MTB infection.