显微镜观察药物敏感性试验检测结核分枝杆菌对吡嗪酰胺的敏感性

Using microscopic-observation drug-susceptibility assay to detect susceptibility of Mycobacterium tuberculosis to pyrazinamide

目的：评价显微镜观察药物敏感性（microscopic-observation drug-susceptibility，MODS）试验检测结核分枝杆菌对吡嗪酰胺（pvrazinamide，PZA）敏感性的价值。方法：采用pncA基因测序法、MGIT960 PZA法、Wayne法及MODS法检测53株结核分枝杆菌对PZA的敏感性。结果：①pncA基因测序结果显示，53株结核分枝杆菌中30株发生了不同位点的突变，另23株为野生型；MGIT960 PZA法检测结果显示，其中22株对PZA敏感，31株对PZA耐药；经wavne法检测，28株为PZase阳性，25株为Pzase阴性。②MODS法检测结果显示，53株结核分枝杆菌中，12株在规定时间内未生长．41株在5-14d获得结果，平均时间为7．5d。③MODS法检测结果与pncA测序法、MGIT960PZA法及Wavne法比较，符合率分别为95-3％、97．6％及87．8％。结论：MODS法可快速、准确、经济地检测结核分枝杆菌对PZA的敏感性，但小部分菌株会受pH影响而无法生长。对于无法生长的菌株可联合Wayne法、pncA基因测序法、MGIT960PZA法弥补检测的不足．以实现用最低的检测成本完成准确快捷的检测。

Objective To evaluate the ability of the microscopic- observation drug-susceptibility （MODS） assay for detecting the susceptibility of Mycobacterium tuberculosis to pyrazinamide. Methods The susceptibility of Mycobocterium tuberculosis to pyrazinamide was measured by pncA gene sequencing, MGIT 960 PZA, Wayne assay and MODS . ResuLts The results of pncA gene sequencing showed that 30 of the 53 isolates had mutation at various locus and other 23 strains were of wild type. MGIT 960 PZA showed that 22 strains were PZA sensitive and 31 strains were PZA resistant. Wayne assay showed that 28 of 53 isolates were PZase positive and 25 were PZase negative. By the MODS method, 12 of 53 strains did not grow within 14 days incubation, and results were obtained in 41 isolates between the 5th and 14th day; the average was 7.5 days. The concordance rates of pncA sequencing, MGIT 960 PZA and Wayne assay with MODS were 95.3%, 97.6% and 87.8%, respectively. Conclusions The MODS assay could detect the susceptibility of Mycobacterium tuberculosis to pyrazinamide fast, exactly and conveniently. Few of the strains could not grow by using MODS because of the influence of pH. For this part of isolates, the testing of susceptibility could be achieved by the combined use of pncA gene sequencing, Wayne assay and MGIT 960 PZA.