DeGruy Kyle, Klein Katherine, Rey Zilma, Hall Patricia, Kim Andrea, Alexander Heather
Centers for Disease Control and Prevention, Division of Global HIV and TB, International Laboratory Branch, Atlanta, Georgia, United States.
Centers for Disease Control and Prevention, Division of TB Elimination, Laboratory Branch, Atlanta, Georgia, United States.
Afr J Lab Med. 2020 Sep 29;9(1):1166. doi: 10.4102/ajlm.v9i1.1166. eCollection 2020.
Proficiency testing (PT) is part of a comprehensive quality assurance programme, which is critical to ensuring patients receive accurate and reliable diagnostic testing. Implementation of the Cepheid Xpert® MTB/RIF assay to aid in the diagnosis of tuberculosis has expanded rapidly in recent years; however, PT material for Xpert MTB/RIF is not readily available in many resource-limited settings.
To develop an accurate and precise PT material based on the dried tube specimen (DTS) method, using supplies and reagents available in most tuberculosis culture laboratories.
Dried tube specimens were produced at the United States Centers for Disease Control and Prevention from 2013 to 2015 by inactivating liquid cultures of well-characterised mycobacterial strains. Ten percent of DTS produced were tested with Xpert MTB/RIF and evaluated for accuracy and precision.
Validation testing across eight rounds of PT demonstrated that DTS are highly accurate, achieving an average of 96.8% concordance with the Xpert MTB/RIF results from the original mycobacterial strains. Dried tube specimen testing was also precise, with cycle threshold standard deviations below two cycles when inherent test cartridge variability was low.
Dried tube specimens can be produced using equipment already present in tuberculosis culture laboratories, making Xpert MTB/RIF PT scale-up more feasible in resource-limited settings. Use of DTS may fill the gap in tuberculosis laboratory access to external quality assessment, which is an essential component of a comprehensive continuous quality improvement programme.
能力验证（PT）是全面质量保证计划的一部分，对于确保患者获得准确可靠的诊断检测至关重要。近年来，赛沛Xpert® MTB/RIF检测法在结核病诊断中的应用迅速扩大；然而，在许多资源有限的环境中，Xpert MTB/RIF的PT材料并不容易获得。
利用大多数结核病培养实验室现有的耗材和试剂，基于干管标本（DTS）方法开发一种准确且精确的PT材料。
2013年至2015年，美国疾病控制与预防中心通过灭活特征明确的分枝杆菌菌株的液体培养物来制备干管标本。所制备的DTS中有10%用Xpert MTB/RIF进行检测，并评估其准确性和精密度。
八轮PT的验证测试表明，DTS高度准确，与原始分枝杆菌菌株的Xpert MTB/RIF结果平均一致性达到96.8%。当检测试剂盒的固有变异性较低时，干管标本检测也具有精确性，循环阈值标准差低于两个循环。
可以使用结核病培养实验室现有的设备制备干管标本，这使得在资源有限的环境中扩大Xpert MTB/RIF PT的规模变得更加可行。使用DTS可能填补结核病实验室在外部质量评估方面的空白，而外部质量评估是全面持续质量改进计划的重要组成部分。
