We describe the design, development, analytical performance, and a limited clinical evaluation of the 10-color Xpert MTB/XDR assay (CE-IVD only, not for sale in the United States). This assay is intended as a reflex test to detect resistance to isoniazid (INH), fluoroquinolones (FLQ), ethionamide (ETH), and second-line injectable drugs (SLIDs) in unprocessed sputum samples and concentrated sputum sediments which are positive for Mycobacterium tuberculosis. The Xpert MTB/XDR assay simultaneously amplifies eight genes and promoter regions in M. tuberculosis and analyzes melting temperatures (T_ms) using sloppy molecular beacon (SMB) probes to identify mutations associated with INH, FLQ, ETH, and SLID resistance. Results can be obtained in under 90 min using 10-color GeneXpert modules. The assay can differentiate low- versus high-level resistance to INH and FLQ as well as cross-resistance versus individual resistance to SLIDs by identifying mutation-specific T_ms or T_m patterns generated by the SMB probes. The assay has a limit of detection comparable to that of the Xpert MTB/RIF assay and successfully detected 16 clinically significant mutations in a challenge set of clinical isolate DNA. In a clinical study performed at two sites with 100 sputum and 214 clinical isolates, the assay showed a sensitivity of 94% to 100% and a specificity of 100% for all drugs except for ETH compared to that of sequencing. The sensitivity and specificity were in the same ranges as those of phenotypic drug-susceptibility testing. Used in combination with a primary tuberculosis diagnostic test, this assay should expand the capacity for detection of drug-resistant tuberculosis near the point of care.

中文翻译：

---

Xpert MTB/XDR：适用于现场护理设置的 10 色反射测定，可直接从结核分枝杆菌阳性痰液中检测异烟肼、氟喹诺酮和二线注射药物耐药性


我们描述了 10 色 Xpert MTB/XDR 检测（仅限 CE-IVD，不在美国销售）的设计、开发、分析性能和有限的临床评估。该测定旨在作为反射测试，检测结核分枝杆菌阳性的未处理痰样本和浓缩痰沉积物中对异烟肼 (INH)、氟喹诺酮类药物 (FLQ)、乙硫异烟胺 (ETH) 和二线注射药物 (SLID) 的耐药性。 Xpert MTB/XDR 检测同时扩增结核分枝杆菌中的八个基因和启动子区域，并使用草率分子信标 (SMB) 探针分析解链温度 ( T _m s)，以识别与 INH、FLQ、ETH 和 SLID 耐药性相关的突变。使用 10 色 GeneXpert 模块可在 90 分钟内获得结果。该检测可以通过识别 SMB 探针生成的突变特异性T _m s 或T _m模式来区分对 INH 和 FLQ 的低水平耐药性与高水平耐药性，以及对 SLID 的交叉耐药性与个体耐药性。该测定的检测限与 Xpert MTB/RIF 测定相当，并成功检测到临床分离 DNA 挑战组中的 16 个临床显着突变。在两个地点进行的一项临床研究中，涉及 100 份痰液和 214 份临床分离株，结果显示，与测序相比，该检测对除 ETH 之外的所有药物的敏感性为 94% 至 100%，特异性为 100%。敏感性和特异性与表型药敏试验的范围相同。 该检测与原发性结核病诊断测试结合使用，可扩大护理点附近耐药结核病的检测能力。