采用结核分枝杆菌参考菌株和临床分离株对四种一线药物进行微观观察药物敏感性试验的优化。
Optimization of the microscopic observation drug susceptibility assay for four first-line drugs using Mycobacterium tuberculosis reference strains and clinical isolates.
机构信息
Department of International Cooperation, Japan Anti-Tuberculosis Association, 3-1-24 Matsuyama Kiyose-shi, Tokyo 204-8533, Japan; Department of Mycobacterium Reference and Research, Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, 3-1-24 Matsuyama Kiyose-shi, Tokyo 204-8533, Japan.
Department of Mycobacterium Reference and Research, Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, 3-1-24 Matsuyama Kiyose-shi, Tokyo 204-8533, Japan.
出版信息
J Microbiol Methods. 2014 Jun;101:44-8. doi: 10.1016/j.mimet.2014.03.014. Epub 2014 Apr 6.
OBJECTIVE
The aim of this study is to determine the appropriate cut-off value and turnaround time of the microscopic observation drug susceptibility assay (MODS) for isoniazid (INH), rifampicin (RMP), streptomycin (STR), and ethambutol (EMB).
DESIGN
A total of 39 Mycobacterium tuberculosis strains with confirmed drug susceptibility (reference strains) were tested with a range of drug concentrations to determine the optimal cut-off values for INH, RMP, STR, and EMB by MODS. Standard drug susceptibility testing (DST) results were evaluated relative to the Löwenstein-Jensen (L-J) proportion method. Following which, the performance of MODS was evaluated again using 36 sputum samples from patients with tuberculosis (TB) using the cut-off values determined in the aforementioned process.
RESULTS
With 39 reference strains, DST identified the following cut-off values: 0.8μg/ml INH (sensitivity, 96.0%; specificity, 92.9%), 2.0μg/ml RMP (sensitivity, 100%; specificity, 95.5%), 4.0μg/ml STR (sensitivity, 90.5%; specificity, 93.8%), and 4.0μg/ml EMB (sensitivity, 100%; specificity, 91.7%). When these cut-off values were used to analyze the 36 clinical isolates, the sensitivity and specificity of MODS were 100% and 93.1% for INH, 100% and 93.8% for RMP, 87.5% and 96.4% for STR, and 100% and 88.2% for EMB, respectively. The turnaround time for these clinical specimens was 9.0days by MODS (95% CI: 5.3-12.7), compared with 11.7days (95% CI: 9.5-13.9) for smear negative specimens.
CONCLUSION
Our study identified the optimal cut-off values of the four first-line drugs for MODS based on a wide concentration range. With the optimal cut-off values determined in this study, MODS showed high discriminatory efficiency for DST. This study also demonstrated that MODS is useful for rapid diagnosis of drug-resistant TB even for a smear negative specimen, despite the fact that it generally uses smear positive specimens as direct DST.
目的
本研究旨在确定分枝杆菌微量药物敏感性检测（MODS）对异烟肼（INH）、利福平（RMP）、链霉素（STR）和乙胺丁醇（EMB）的适宜截止值和周转时间。
设计
对 39 株经确认药物敏感性的结核分枝杆菌（参考株）进行一系列药物浓度检测，通过 MODS 确定 INH、RMP、STR 和 EMB 的最佳截止值。用 Löwenstein-Jensen（L-J）比例法对标准药物敏感性检测（DST）结果进行评估。然后，使用 36 例结核病（TB）患者的痰标本，根据上述过程确定的截止值，再次评估 MODS 的性能。
结果
用 39 株参考株进行 DST 鉴定，得到以下截止值：0.8μg/ml INH（敏感性 96.0%，特异性 92.9%）、2.0μg/ml RMP（敏感性 100%，特异性 95.5%）、4.0μg/ml STR（敏感性 90.5%，特异性 93.8%）和 4.0μg/ml EMB（敏感性 100%，特异性 91.7%）。当使用这些截止值分析 36 例临床分离株时，MODS 对 INH 的敏感性和特异性分别为 100%和 93.1%，对 RMP 为 100%和 93.8%，对 STR 为 87.5%和 96.4%，对 EMB 为 100%和 88.2%。这些临床标本的周转时间为 9.0 天（95%CI：5.3-12.7），而阴性痰标本为 11.7 天（95%CI：9.5-13.9）。
结论
本研究在较宽的浓度范围内确定了 MODS 四种一线药物的最佳截止值。根据本研究确定的最佳截止值，MODS 对 DST 具有较高的鉴别效率。本研究还表明，MODS 即使对阴性痰标本也可用于快速诊断耐药性结核，尽管它通常使用阳性痰标本进行直接 DST。
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