Comparative evaluation of Lowenstein-Jensen proportion method, BacT/ALERT 3D system, and enzymatic pyrazinamidase assay for pyrazinamide susceptibility testing of Mycobacterium tuberculosis
Comparative evaluation of Lowenstein-Jensen proportion method, BacT/ALERT 3D system, and enzymatic pyrazinamidase assay for pyrazinamide susceptibility testing of Mycobacterium tuberculosis
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DOI：
10.1128/jcm.00951-06
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发表时间：
2007-01-01
影响因子：
9.4
通讯作者：
Katoch, V. A.
中科院分区：
文献类型：
--
作者：
Singh, Pushpendra;Wesley, Clement;Katoch, V. A.
吡嗪酰胺（Pyrazinamide， PZA）对半休眠结核杆菌具有抗菌活性，是重要的一线抗结核药物。尽管其体内活性非常高，但其体外活性不明显，除非有酸性环境，这使得常规方法难以进行PZA药敏试验。因此，本研究计划评估BacT/ALERT 3D比色系统的性能，并将结果与传统测试（即“wenstein-jensen （LJ）比例法（pH 4.85）和Wayne’s pyrazinamidase (PZase) assay）的结果进行比较，使用107个临床分离株。第一轮检测后，各检测结果的符合率为89.71%，重新检测后，不一致的结果得到解决，符合率为92.52%。延长PZase试管的孵育时间长达10天，可以增加PZase测试的特异性。LJ比例与BacT/ALERT 31、LJ比例与PZase、BacT/ALERT 3D、PZase的一致性分别为99.06%、93.46%、92.52%。以Q结果为金标准，BacT/ALERT 3D法和PZase法的灵敏度分别为100和82.85%，特异性为98.61%。BacT/ALERT 3D与PZase检测的敏感性差异有统计学意义（P = 0.025）。BacT/ALERT 3D检测耐药和敏感结果的平均周转时间分别为8.04和11.32 d。虽然PZase测定法和LJ比例法的主要局限性分别是对先前治疗过的患者敏感性较低和时间要求较长，但BacT/ ALERT 3D系统具有快速、高灵敏度和特异性。
Pyrazinamide (PZA) is an important first-line antituberculosis drug because of its sterilizing activity against semidormant tubercle bacilli. In spite of its very high in vivo activity, its in vitro activity is not apparent unless an acidic environment is available, which makes PZA susceptibility testing difficult by conventional methods. The present study was, therefore, planned to assess the performance of the colorimetric BacT/ALERT 3D system and compare the results with those from conventional tests, i.e., the "wenstein-jensen (LJ) proportion method (pH 4.85) and Wayne's pyrazinamidase (PZase) assay, using 107 clinical isolates. The concordance among all of these tests was 89.71% after the first round of testing and reached 92.52% after resolution of the discordant results by retesting. Prolonged incubation of the PZase tube for up to 10 days was found to increase the specificity of the PZase test. The concordances between LJ proportion and BacT/ALERT 31), LJ proportion and the PZase assay, and BacT/ALERT 3D and the PZase assay were found to be 99.06%, 93.46%, and 92.52%, respectively. Using the Q results as the gold standard, the sensitivities of BacT/ALERT 3D and the PZase assay were 100 and 82.85%, respectively, while the specificity was 98.61% for both of the tests. The difference between the sensitivities of BacT/ALERT 3D and the PZase assay was significant (P = 0.025). The mean turnaround times for the detection of resistant and susceptible results by BacT/ALERT 3D were 8.04 and 11.32 days, respectively. While the major limitations associated with the PZase assay and the LJ proportion method are lower sensitivity in previously treated patients and a longer time requirement, respectively, the BacT/ ALERT 3D system was found to be rapid, highly sensitive, and specific.