Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia.
Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia.
Int J Infect Dis. 2020 Jan;90:213-218. doi: 10.1016/j.ijid.2019.10.041. Epub 2019 Nov 2.
Appropriate technology tests are needed for Mycobacterium tuberculosis drug-susceptibility testing (DST) in resource-constrained settings. This study was performed to evaluate the MDR/XDR-TB Colour Test (a colour platethin-layer agar test; TB-CX) for M. tuberculosis DST by directly testing sputum at University of Gondar Hospital.
Sputum samples were each divided into two aliquots. One aliquot was mixed with disinfectant and applied directly to the TB-CX quadrant petri-plate containing culture medium with and without isoniazid, rifampicin, or ciprofloxacin. Concurrently, the other aliquot was decontaminated with sodium hydroxide, centrifuged, and cultured on Lӧwenstein-Jensen medium; the stored M. tuberculosis isolates were then sub-cultured in BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 for reference DST.
The TB-CX test yielded DST results for 94% (123/131) of positive samples. For paired DST results, the median number of days from sputum processing to DST was 12 for TB-CX versus 35 for LJ-MGIT (p<0.001). Compared with LJ-MGIT for isoniazid, rifampicin, and multidrug-resistant tuberculosis, TB-CX had 59%, 96%, and 95% sensitivity; 96%, 94%, and 98% specificity; and 85%, 94%, and 98% agreement, respectively. All ciprofloxacin DST results were susceptible by both methods.
The TB-CX test was simple and rapid for M. tuberculosis DST. Discordant DST results may have resulted from sub-optimal storage and different isoniazid concentrations used in TB-CX versus the reference standard test.
在资源有限的环境中，需要进行适当的技术测试来进行结核分枝杆菌药敏试验（DST）。本研究旨在通过在贡德尔大学医院直接检测痰标本，评估 MDR/XDR-TB 色测试（一种颜色平板层琼脂测试；TB-CX）用于结核分枝杆菌 DST 的能力。
将痰标本均分为两份。一份与消毒剂混合，直接涂于含有异烟肼、利福平或环丙沙星的 TB-CX 平板培养基的象限板中。同时，另一份用氢氧化钠处理、离心，并接种于 Löwenstein-Jensen 培养基；然后将储存的结核分枝杆菌分离物再培养于 BACTEC 分枝杆菌生长指示管（MGIT）960 中，进行参考 DST。
TB-CX 试验对 94%（123/131）的阳性样本得出了 DST 结果。对于配对 DST 结果，从痰处理到 DST 的中位数时间，TB-CX 为 12 天，LJ-MGIT 为 35 天（p<0.001）。与 LJ-MGIT 相比，TB-CX 对异烟肼、利福平、耐多药结核分枝杆菌的敏感性分别为 59%、96%和 95%；特异性分别为 96%、94%和 98%；一致性分别为 85%、94%和 98%。两种方法的环丙沙星 DST 结果均为敏感。
TB-CX 试验用于结核分枝杆菌 DST 简单快速。不一致的 DST 结果可能是由于 TB-CX 与参考标准测试中使用的储存和异烟肼浓度不理想所致。
