Kohli Amrish, Bashir Gulnaz, Fatima Akeela, Jan Abiroo, Wani Nayeem-U-Din, Ahmad Junaid
Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, Jammu and Kashmir, India.
Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, Jammu and Kashmir, India.
Int J Mycobacteriol. 2016 Dec;5(4):469-474. doi: 10.1016/j.ijmyco.2016.06.006. Epub 2016 Jun 25.
OBJECTIVE/BACKGROUND: Early initiation of therapy in patients with tuberculosis is imperative for its control. Conventional methods of susceptibility testing such as the proportion method (PM) require visual detection and counting of colonies that takes up to 6weeks. Rapid and simple phenotypic methods that have been endorsed by the World Health Organization can serve as alternatives.
In this study, we evaluated the colorimetric nitrate reductase assay, which utilizes the detection of nitrate reduction as an indicator of growth much earlier compared with PM (within 7-14days). The susceptibility of 75 clinical isolates of Mycobacterium tuberculosis to four first-line antitubercular drugs was tested by nitrate reductase assay and compared with the standard PM. In this assay, inoculation was done on both drug-free and drug-containing Löwenstein-Jensen medium containing sodium nitrate. After incubation for 7-14days, reduction to nitrite was taken as an indicator of growth, which was detected by color change on addition of Griess reagent.
Agreement between nitrate reductase assay and PM was 100% for rifampicin, 97.30% for isoniazid, 93.30% for streptomycin, and 98.60% for ethambutol. Cost/isolate with this assay was found to be approximately two times lesser than that of PM. All results were obtained in 7-14days by nitrate reductase assay, which was significantly rapid compared with 42days taken for obtaining results by PM.
Nitrate reductase assay can be used as a rapid and inexpensive method for drug-susceptibility testing of M. tuberculosis for first-line antitubercular drugs without compromising accuracy of standard methods.
目的/背景：结核病患者尽早开始治疗对控制病情至关重要。传统的药敏试验方法，如比例法（PM），需要目视检测和计数菌落，耗时长达6周。世界卫生组织认可的快速简单表型方法可作为替代方法。
在本研究中，我们评估了比色硝酸还原酶试验，该试验利用硝酸还原检测作为生长指标，比PM更早（7 - 14天内）。通过硝酸还原酶试验检测75株结核分枝杆菌临床分离株对四种一线抗结核药物的敏感性，并与标准PM进行比较。在该试验中，在不含药物和含药物的含硝酸钠的罗 - 琴培养基上进行接种。培养7 - 14天后，亚硝酸盐还原作为生长指标，通过加入格里斯试剂后的颜色变化进行检测。
硝酸还原酶试验与PM对利福平的一致性为100%，对异烟肼为97.30%，对链霉素为93.30%，对乙胺丁醇为98.60%。发现该试验每株的成本约为PM的两倍。通过硝酸还原酶试验在7 - 14天内获得所有结果，与PM获得结果所需的42天相比，显著更快。
硝酸还原酶试验可作为一种快速且廉价的方法，用于结核分枝杆菌对一线抗结核药物的药敏试验，而不影响标准方法的准确性。
