According to World Health Organization (WHO), drug-resistant tuberculosis (DR-TB) is a major contributor to antimicrobial resistance globally and continues to be a public health threat. Annually, about half a million people fall ill with DR-TB globally. The gradual increase in resistance to fluoroquinolones (FQs) and second-line injectable drugs (SLIDs), poses a serious threat to effective TB control and adequate patient management. Therefore, WHO suggests the use of GenoType MTBDRsl v.2.0 assay for detection of multiple mutations associated with FQs and SLIDs. Hence, the study was conducted to determine the prevalence of resistance to FQs and SLIDs by comparing direct GenoType MTBDRsl v.2.0 assay with phenotypic drug susceptibility testing (DST). The study was conducted on 1320 smear positive sputum samples from a total of 2536 RR-TB, confirmed by GeneXpert MTB/RIF. The smear positive specimens were decontaminated, and DNA extraction was performed. Furthermore, the extracted DNA was used for GenoType MTBDRsl v.2.0 assay. While 20% of the decontaminated specimens were inoculated in Mycobacterium growth indicator tube (MGIT) for drug susceptibility testing (DST). Out of 1320 smear positive sputum samples, 1178 were identified as Mycobacterium tuberculosis complex (MTBC) and remaining were negative by GenoType MTBDRsl v.2.0 assay. Of the 1178 MTBC positive, 26.6% were sensitive to both FQs and SLIDs, whereas 57.3% were only FQs resistant and 15.9% were resistant to both FQs and SLIDs. Further DST of 225 isolates by liquid culture showed that 17% were sensitive to both FQs and SLIDs, 61.3% were only FQs resistant and 21.3% were resistant to both. The specificity for FQs and SLIDs was 92.31% and 100% whereas sensitivity was 100% respectively by GenoType MTBDRsl v.2.0 assay in direct sputum samples. Our study clearly suggests that GenoType MTBDRsl v.2.0 assay is a reliable test for the rapid detection of resistance to second-line drugs after confirmation by GeneXpert MTB/RIF assay for RR-TB. Though, high rate FQ (ofloxacin) resistance was seen in our setting, moxifloxacin could be used as treatment option owing to very low resistance.

中文翻译：

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通过 GenoType MTBDRsl v.2.0 测定法直接检测痰标本中对氟喹诺酮类药物/SLIDs 的耐药性 印度东部北方邦的一项研究

据世界卫生组织 (WHO) 称，耐药结核病 (DR-TB) 是全球抗菌素耐药性的主要贡献者，并继续构成公共卫生威胁。每年，全球约有 50 万人患有耐药结核病。对氟喹诺酮类药物（FQs）和二线注射药物（SLIDs）的耐药性逐渐增加，对有效的结核病控制和充分的患者管理构成了严重威胁。因此，WHO 建议使用 GenoType MTBDRsl v.2.0 检测来检测与 FQ 和 SLID 相关的多个突变。因此，该研究通过比较直接的 GenoType MTBDRsl v.2.0 测定法与表型药物敏感性测试 (DST) 来确定对 FQ 和 SLID 的耐药率。该研究对来自总共 2536 名 RR-TB 的 1320 份涂阳痰样本进行，由 GeneXpert MTB/RIF 确认。对涂片阳性标本进行去污处理，并进行 DNA 提取。此外，提取的 DNA 用于 GenoType MTBDRsl v.2.0 测定。将20%的去污标本接种于分枝杆菌生长指示管（MGIT）中进行药敏试验（DST）。在 1320 份涂阳痰样本中，1178 份被鉴定为结核分枝杆菌复合体 (MTBC)，其余的通过 GenoType MTBDRsl v.2.0 检测为阴性。在 1178 例 MTBC 阳性者中，26.6% 对 FQs 和 SLIDs 均敏感，而 57.3% 仅对 FQs 耐药，15.9% 对 FQs 和 SLIDs 均耐药。进一步通过液体培养对 225 个分离株进行药敏试验表明，17% 对 FQs 和 SLIDs 均敏感，61.3% 仅对 FQs 耐药，21.3% 对两者均耐药。在直接痰液样本中通过 GenoType MTBDRsl v.2.0 测定法对 FQ 和 SLID 的特异性分别为 92.31% 和 100%，而敏感性分别为 100%。我们的研究清楚地表明，在通过 GeneXpert MTB/RIF 检测对 RR-TB 进行确认后，GenoType MTBDRsl v.2.0 检测是快速检测对二线药物耐药性的可靠检测方法。虽然在我们的环境中发现了高比率的 FQ（氧氟沙星）耐药性，但由于耐药性非常低，莫西沙星可以用作治疗选择。