Kaul K L
Department of Pathology, Evanston Northwestern Healthcare, 2650 Ridge Ave., Evanston, IL 60201, USA.
Clin Chem. 2001 Aug;47(8):1553-8.
Nucleic acid amplification technologies such as PCR are revolutionizing the detection of infectious pathogens such as tuberculosis (TB). Amplification technology offers the potential for the diagnosis of TB in a few hours with a high degree of sensitivity and specificity. However, molecular assays neither replace nor reduce the need for conventional smear and culture, speciation, and antibiotic sensitivity assays.
We undertook prospective studies of sputum samples to assess the performance of two PCR-based assays for the detection of TB as well as the impact of more rapid availability of test results on patient care.
The sensitivity of both the in-house and Amplicor PCR assays was 100% for smear-positive sputa. For smear-negative sputa (two sputum samples collected during the first 24 h of hospitalization), the sensitivity was 85% for our in-house PCR assay and 74% for the Roche PCR assay. Approximately 10% of the smear- and culture-negative sputa yielded positive PCR results; however, more than one-half of these were positive with both the in-house and Amplicor assays, suggesting the presence of TB DNA or organisms. Several of these came from patients whose other samples grew Mycobacterium tuberculosis during the same admission, and others came from patients who had previously treated TB. Overall, the specificities of the in-house and Amplicor PCR assays in smear-negative patients were 86% and 93%, respectively.
Molecular detection of slow-growing pathogens such as M. tuberculosis have the potential to improve clinical care through a dramatic reduction in the time required for detection and may provide substantial savings in the overall cost of care of a patient compared with conventional smear, culture, and speciation alone, despite the fact that conventional assays must still be performed for speciation of nontuberculous mycobacteria and for full assessment of antibiotic sensitivity.
诸如聚合酶链反应（PCR）之类的核酸扩增技术正在彻底改变对结核病（TB）等传染性病原体的检测。扩增技术为在数小时内诊断结核病提供了潜力，具有高度的敏感性和特异性。然而，分子检测既不能替代也不能减少对传统涂片和培养、菌种鉴定以及抗生素敏感性检测的需求。
我们对痰标本进行了前瞻性研究，以评估两种基于PCR的检测方法对结核病的检测性能，以及检测结果更快可得对患者护理的影响。
对于涂片阳性痰标本，内部PCR检测法和Amplicor PCR检测法的敏感性均为100%。对于涂片阴性痰标本（住院后24小时内采集的两份痰标本），我们的内部PCR检测法敏感性为85%，罗氏PCR检测法敏感性为74%。约10%的涂片和培养阴性痰标本PCR检测结果呈阳性；然而，其中一半以上在内部检测法和Amplicor检测法中均呈阳性，提示存在结核DNA或微生物。其中一些标本来自同一住院期间其他标本培养出结核分枝杆菌的患者，另一些来自既往有结核病治疗史的患者。总体而言，涂片阴性患者中内部PCR检测法和Amplicor PCR检测法的特异性分别为86%和93%。
对结核分枝杆菌等生长缓慢的病原体进行分子检测有可能通过大幅缩短检测所需时间来改善临床护理，与仅进行传统涂片、培养和菌种鉴定相比，可能会大幅节省患者的总体护理成本，尽管对于非结核分枝杆菌的菌种鉴定和抗生素敏感性的全面评估仍必须进行传统检测。
