Pfyffer G E, Kissling P, Jahn E M, Welscher H M, Salfinger M, Weber R
Swiss National Center for Mycobacteria, Department of Medical Microbiology, University of Zurich, Switzerland.
J Clin Microbiol. 1996 Apr;34(4):834-41. doi: 10.1128/jcm.34.4.834-841.1996.
The Gen-Probe Amplified Mycobacterium tuberculosis Direct Test (MTD) was adapted to be used for cerebrospinal fluid (CSF) and a large variety of other nonrespiratory specimens. Standardized with artificially spiked dilution series of CSF, the modified MTD procedure consists of (i) increasing the amount of sample 10-fold, (ii) pretreating the specimen with a detergent, and (iii) increasing the amplification time from 2 to 3 h. Performance of MTD in a clinical mycobacteriology laboratory was tested over an extended period of time, involving a total of 322 nonrespiratory as well as 1,117 respiratory specimens from 998 patients. Results from MTD were compared with those from microscopy, culture, analysis of tuberculostearic acid by gas-liquid chromatography-mass spectrometry (CSF only), and the final clinical diagnosis. When MTD results were compared with resolved data, the sensitivity, specificity, and positive and negative predictive values for MTD were 93.1, 97.7, 90.0, and 98.5%, respectively, for nonrespiratory specimens and 86.6, 96.4, 76.8, and 98.1%, respectively, for respiratory specimens. Our data demonstrate that (i) MTD is a robust, highly sensitive and specific technique for the rapid detection of M. tuberculosis complex in all types of clinical specimens, (ii) there was no statistically significant difference (P > 0.005) in sensitivity and specificity for nonrespiratory compared with respiratory specimens, and (iii) repeating all MTDs which yield a result between 30,000 and 200,000 relative light units would help prevent a large number of false positives and, thus, enhance test specificity.
基因探针结核分枝杆菌直接扩增试验（MTD）经调整后用于脑脊液（CSF）及多种其他非呼吸道标本。通过人工添加不同稀释度的脑脊液系列进行标准化后，改良的MTD程序包括：（i）将样本量增加10倍；（ii）用去污剂对标本进行预处理；（iii）将扩增时间从2小时延长至3小时。在临床分枝杆菌学实验室对MTD的性能进行了长期测试，共涉及998例患者的322份非呼吸道标本以及1117份呼吸道标本。将MTD的结果与显微镜检查、培养、气液色谱 - 质谱联用分析结核硬脂酸（仅针对脑脊液）以及最终临床诊断的结果进行比较。当将MTD结果与已确诊数据进行比较时，MTD对于非呼吸道标本的敏感性、特异性、阳性预测值和阴性预测值分别为93.1%、97.7%、90.0%和98.5%，对于呼吸道标本分别为86.6%、96.4%、76.8%和98.1%。我们的数据表明：（i）MTD是一种用于快速检测各类临床标本中结核分枝杆菌复合群强大、高度敏感且特异的技术；（ii）非呼吸道标本与呼吸道标本在敏感性和特异性方面无统计学显著差异（P>0.005）；（iii）对所有产生相对光单位在30,000至200,000之间结果的MTD进行重复检测，将有助于防止大量假阳性结果，从而提高检测特异性。
