Department of Clinical Microbiology and Infectious Diseases, University of the Witwatersrand, Johannesburg, South Africa, National Health Laboratory Service (NHLS), Johannesburg, South Africa.
National Priority Programmes, NHLS, Johannesburg, South Africa.
Int J Tuberc Lung Dis. 2021 Oct 1;25(10):832-838. doi: 10.5588/ijtld.21.0154.
South Africa´s diagnostic algorithm for TB diagnosis from 2011 to 2017 employed the Xpert MTB/RIF assay as the initial screening test for TB diagnosis and rifampicin (RIF) susceptibility, followed by submission of a specimen for GenoType MTBDR. This study aimed to determine the concordance between the two assays in terms of RIF susceptibility and explore reasons for discordance. This was a retrospective laboratory-based study that included all MTBDR results of tests performed at the Braamfontein Mycobacteriology Referral Laboratory between 1 September 2014 and 31 August 2015. The patient´s Xpert RIF result was linked with the MTBDR result. The overall concordance between RIF susceptibility results was 96.4%. There were 68 discordant RIF results. The most common reasons for discordance identified were possible false Xpert RIF-resistant results (22%), mixed infection/heteroresistance (16%), transcription errors (7%) and erroneous manual interpretation of the MTBDR strip (7%). Xpert RIF resistance detected using delayed hybridisation was associated with discordance. The overall concordance between the MTBDR and Xpert RIF results were very good. Management of discordance should include repeat specimens for Xpert and MTBDR and B sequencing. All variables should then be considered before treatment regimens are altered.
南非从 2011 年至 2017 年的结核病诊断算法采用 Xpert MTB/RIF 检测作为结核病诊断和利福平（RIF）耐药性的初始筛查试验，然后提交标本进行 GenoType MTBDR 检测。本研究旨在确定两种检测方法在 RIF 耐药性方面的一致性，并探讨不一致的原因。这是一项回顾性的基于实验室的研究，包括 2014 年 9 月 1 日至 2015 年 8 月 31 日在 Braamfontein 分枝杆菌参考实验室进行的所有 MTBDR 检测结果。患者的 Xpert RIF 结果与 MTBDR 结果相关联。RIF 耐药性结果的总体一致性为 96.4%。有 68 个 RIF 结果不一致。不一致的最常见原因是可能的假 Xpert RIF 耐药结果（22%）、混合感染/异质性耐药（16%）、转录错误（7%）和 MTBDR 条带的错误手动解释（7%）。使用延迟杂交检测到的 Xpert RIF 耐药性与不一致性相关。MTBDR 和 Xpert RIF 结果的总体一致性非常好。对不一致性的处理应包括重复进行 Xpert 和 MTBDR 检测以及 B 测序。在改变治疗方案之前，应考虑所有变量。
