Ethiopian Public Health Institute, Addis Ababa, Ethiopia.
BMC Infect Dis. 2020 Jan 30;20(1):87. doi: 10.1186/s12879-020-4817-2.
Xpert® MTB/RIF assay is currently used in Ethiopia for the rapid diagnosis of Mycobacterium tuberculosis (MTB) and mutations that confer Rifampicin resistance. Rifampicin resistance is determined based on any mutation in the 81 bp of rpoB gene using five overlapping probes represented as Probe A (codons 507-511), Probe B (codons 512-518), Probe C (codons 518-523), Probe D (codons 523-529) and Probe E (codons 529-533). In this review, we assessed the frequency of missed probe types for Rifampicin Resistance results.
Data were reviewed from specimens received and tested using Xpert® MTB/RIF assay at Ethiopian National Tuberculosis Reference Laboratory, in Addis Ababa from 15 July 2016 to 31 December 2018 retrospectively. All archived data were reviewed carefully to describe missed probe types and the quantity of DNA in the sample.
A total of 100 specimens were reported as MTB Detected Rifampicin Resistance Detected by Xpert® MTB/RIF assay. More than half (55%) of these results were reported from male patients. The median age was 28.0 years (5 months to 88 years). Majorities (62%) of the cases were detected from sputum. Among the total of 38 extrapulmonary samples, lymph node aspirates were accounted for 50% (19/38). The most common mutations (81.0%) were found in the Probe E region followed by Probe D (10.0%), and Probe B (3.0%). Mutations in Probe A and Probe C regions were not observed. However, six (6.0%) Rifampicin resistance cases were found without any missed probe type. The delta Ct max is ≥4.3. No specimen yielded Rifampicin resistance associated with more than one probe failure or mutation combinations.
Mutations associated with Probe E (codons 529-533) region were identified as the commonest rpoB gene mutations. The Rifampicin resistance results found without any identified missing probe needs further study. The lower DNA amount was observed in extrapulmonary specimens compared with sputum.
Xpert® MTB/RIF 检测法目前在埃塞俄比亚用于快速诊断结核分枝杆菌（MTB）和赋予利福平耐药性的突变。利福平耐药性是基于 rpoB 基因的 81bp 中任何突变来确定的，该突变使用 5 个重叠探针来表示，分别为探针 A（密码子 507-511）、探针 B（密码子 512-518）、探针 C（密码子 518-523）、探针 D（密码子 523-529）和探针 E（密码子 529-533）。在这项研究中，我们评估了 Rifampicin Resistance 结果中缺失探针类型的频率。
回顾性分析了 2016 年 7 月 15 日至 2018 年 12 月 31 日埃塞俄比亚国家结核病参考实验室收到并使用 Xpert® MTB/RIF 检测法检测的标本数据。仔细审查所有存档数据以描述缺失探针类型和样本中的 DNA 量。
共报告了 100 份 Xpert® MTB/RIF 检测法检测到 MTB 并检测到 Rifampicin 耐药的标本。这些结果中超过一半（55%）来自男性患者。中位年龄为 28.0 岁（5 个月至 88 岁）。大多数（62%）病例来自痰液。在总共 38 份肺外样本中，淋巴结抽吸物占 50%（19/38）。最常见的突变（81.0%）位于探针 E 区域，其次是探针 D（10.0%）和探针 B（3.0%）。未观察到探针 A 和探针 C 区域的突变。然而，发现了 6 例（6.0%）没有任何缺失探针类型的 Rifampicin 耐药病例。delta Ct max≥4.3。没有标本显示与多个探针失效或突变组合相关的 Rifampicin 耐药性。
与探针 E（密码子 529-533）区域相关的突变被鉴定为最常见的 rpoB 基因突变。未发现任何缺失探针的 Rifampicin 耐药性结果需要进一步研究。与痰液相比，肺外标本的 DNA 量较低。
