BACKGROUND The cobas® omni Utility Channel enables users to integrate lab-developed tests (LDTs) on the cobas® 6800 System to perform molecular diagnostics with high-throughput capacity and full automation. At present, there are no CE- or FDA-approved tests for stool pathogens on this system. To assess the performance of stool as a matrix, we evaluated the analytical and clinical performance of an LDT for detection of Clostridioides difficile (C. difficile) toxin B using the Utility Channel (C.diff_UTC). METHODS A 10% stool suspension prepared from liquid stool samples diluted in phosphate buffered saline was used for analysis. Limit of detection (LoD) was determined in six dilutions with 126 replicates/dilution. Clinical evaluation was performed using 514 predetermined patient stool samples from two study sites in Germany. The C.diff_UTC was compared with LC 480 amplification and an LDT or the R-BioPharm C. difficile assay. Discrepant results were further analyzed using the GeneXpert C. difficile assay. RESULTS Limit of detection was 23.48 cfu/mL (95% Confidence Interval [CI]: 19.14-31.01) with inter-run variation of <2 cycle thresholds at 3 × and 10 × LoD. No cross-reactivity was observed with a panel of fecal organisms and pathogens. Bioinformatic analysis showed coverage of the major C. difficile toxinotypes by the primer/probe set. Clinical evaluation revealed sensitivity of 96.7% (95% CI: 88.7-99.6) and specificity of 99.3% (95% CI: 98.0-99.9) compared with the reference method; inhibition rate was 3.5% (18/514). CONCLUSION Using a predesigned primer/probe set, the C.diff_UTC assay features analytical performance and clinical sensitivity and specificity comparable to currently available nucleic acid amplification tests (NAATs) and is suitable for high-throughput testing. This was a proof-of-concept study, indicating the cobas Utility Channel could likely be adapted for other clinically relevant stool pathogens in outbreak scenarios.

中文翻译：

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检测艰难梭菌毒素，作为对临床粪便样品进行全自动高通量RT-PCR的模型测定。

背景技术cobas®omni Utility Channel使用户能够将实验室开发的测试（LDT）集成到cobas®6800系统上，以高通量能力和全自动进行分子诊断。目前，在该系统上尚无CE或FDA批准的粪便病原体检测方法。为了评估粪便作为基质的性能，我们使用实用程序通道（C.diff_UTC）评估了LDT用于检测艰难梭菌（C. difficile）毒素B的分析和临床性能。方法采用稀释在磷酸盐缓冲液中的液态粪便样品制备的10％粪便悬浮液进行分析。在六种稀释液中确定了检测限（LoD），每组126次重复。使用来自德国两个研究地点的514个预定患者粪便样本进行了临床评估。C. 将diff_UTC与LC 480扩增和LDT或R-BioPharm艰难梭菌测定法进行了比较。使用GeneXpert艰难梭菌测定法进一步分析了不一致的结果。结果检测限为23.48 cfu / mL（95％置信区间[CI]：19.14-31.01），在3×和10×LoD下，运行间差异小于2个循环阈值。与一组粪便生物和病原体未观察到交叉反应。生物信息学分析显示，引物/探针组覆盖了主要的艰难梭菌毒素型。临床评估显示，与参考方法相比，灵敏度为96.7％（95％CI：88.7-99.6），特异性为99.3％（95％CI：98.0-99.9）。抑制率为3.5％（18/514）。结论使用预先设计的引物/探针组C。diff_UTC分析具有与目前可用的核酸扩增测试（NAAT）相当的分析性能，临床敏感性和特异性，适用于高通量测试。这是一项概念验证研究，表明cobas Utility Channel在暴发情况下可能适用于其他临床相关的粪便病原体。