Department of Microbiology & Immunology, SMS Medical College, Jaipur, India.
Indian J Med Res. 2010 Jul;132:72-6.
BACKGROUND & OBJECTIVES: Pyrazinamide is an important front line antimycobacterial drug, which is also being used in the treatment of multi drug resistant tuberculosis along with second line drugs in DOTS plus programme. Conventional testing of pyrazinamide on solid medium is difficult as it is active at acidic pH. Therefore, there is a need for a rapid and simple method for susceptibility testing of pyrazinamide. This study was carried out to compare pyrazinamide susceptibility testing by MGIT 960 and two rapid pyrazinamidase activity tests.
Pyrazinamide susceptibility was tested in 136 clinical isolates of Mycobacterium tuberculosis by MGIT 960 and pyrazinamidase activity was tested by classical Wayne's method and modified PZase agar method.
There was 88.9 per cent concordance between MGIT 960 and classical Wayne's method and 93.38 per cent with modified method for pyrazinamidase activity. Using MGIT 960 results as gold standard the sensitivity and specificity of Wayne's method was 88.15 and 90 per cent respectively and that of modified method was 89.4 and 98.3 per cent.
INTERPRETATION & CONCLUSIONS: Our study demonstrates that the modified pyrazinamidase activity test can be used as a screening test to detect resistance to pyrazinamide specially in resource limited settings but confirmation of susceptibility should be done by standard methods like MGIT 960.
吡嗪酰胺是一种重要的一线抗分枝杆菌药物，在 DOTS 加方案中与二线药物一起用于治疗耐多药结核病。由于其在酸性 pH 值下具有活性，因此在固体培养基上常规检测吡嗪酰胺比较困难。因此，需要一种快速简便的吡嗪酰胺药敏检测方法。本研究旨在比较 MGIT 960 和两种快速吡嗪酰胺酶活性检测法用于吡嗪酰胺药敏检测的效果。
采用 MGIT 960 和经典 Wayne 法及改良 PZase 琼脂法检测 136 株结核分枝杆菌临床分离株的吡嗪酰胺药敏性。
MGIT 960 与经典 Wayne 法的符合率为 88.9%，与改良法的符合率为 93.38%。以 MGIT 960 结果为金标准时，Wayne 法的敏感性和特异性分别为 88.15%和 90%，改良法分别为 89.4%和 98.3%。
本研究表明，改良的吡嗪酰胺酶活性检测可作为一种筛选试验，用于检测吡嗪酰胺耐药性，特别是在资源有限的环境中，但应通过标准方法（如 MGIT 960）确认药敏性。
