Ulrich M P, Christensen D R, Coyne S R, Craw P D, Henchal E A, Sakai S H, Swenson D, Tholath J, Tsai J, Weir A F, Norwood D A
Diagnostic Systems Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702-5011, USA.
J Appl Microbiol. 2006 May;100(5):1011-6. doi: 10.1111/j.1365-2672.2006.02810.x.
The Cepheid GeneXpert is a four-site, automated sample preparation and real-time PCR detection system. In this study, the capability of the GeneXpert to isolate and detect nucleic acid from Bacillus anthracis Ames spores was assessed.
A four-plex, dried-down bead cartridge containing PCR reagents specific for the pXO1 and pXO2 plasmids as well as sample processing and inhibition controls was evaluated. For B. anthracis Ames spores harbouring pXO1 and pXO2, samples containing 68 CFU per ml (148 spores per ml) were positive in all four replicates. A limited cross-reactivity panel, which included closely related Bacillus species, was also tested to determine the specificity of the pXO1 and pXO2 assays. No cross-reactivity occurred. Further, B. anthracis Sterne spore samples were analysed to compare results when processed using the GeneXpert to those run directly on the Cepheid SmartCycler without sample processing. The GeneXpert detection capability was three logs lower than the SmartCycler indicating the benefit of incorporating a nucleic acid extraction procedure.
This study demonstrates that the GeneXpert is a rapid and reliable system for simultaneously detecting the B. anthracis virulence plasmids pXO1 and pXO2.
The GeneXpert is the only platform currently available that is capable of both nucleic acid purification and real-time PCR detection enclosed within a single system. Further, all sample manipulations are automated, thus reducing errors associated with manual processing.
赛沛GeneXpert是一种具备四个位点的自动化样本制备及实时PCR检测系统。在本研究中，评估了GeneXpert从炭疽芽孢杆菌埃姆斯菌株孢子中分离和检测核酸的能力。
评估了一种四联干燥珠式试剂盒，其包含针对pXO1和pXO2质粒的PCR试剂以及样本处理和抑制对照。对于携带pXO1和pXO2的炭疽芽孢杆菌埃姆斯菌株孢子，每毫升含68个菌落形成单位（每毫升148个孢子）的样本在所有四次重复检测中均呈阳性。还测试了一个有限的交叉反应性样本组，其中包括密切相关的芽孢杆菌属物种，以确定pXO1和pXO2检测的特异性。未出现交叉反应。此外，对炭疽芽孢杆菌斯特恩菌株孢子样本进行分析，以比较使用GeneXpert处理后的结果与直接在赛沛SmartCycler上运行且未经样本处理的结果。GeneXpert的检测能力比SmartCycler低三个对数级，这表明采用核酸提取程序的益处。
本研究表明，GeneXpert是一种用于同时检测炭疽芽孢杆菌毒力质粒pXO1和pXO2的快速且可靠的系统。
GeneXpert是目前唯一可用的在单个系统内既能进行核酸纯化又能进行实时PCR检测的平台。此外，所有样本操作均为自动化，从而减少了与手工处理相关的误差。
