Tarrand J J, Spicer A D, Gröschel D H
Antimicrob Agents Chemother. 1986 Dec;30(6):852-5. doi: 10.1128/AAC.30.6.852.
Pyrazinamide susceptibility testing of Mycobacterium tuberculosis requires an acid environment. By controlling the method of acidification and the quality and quantity of the inoculum, the test can be performed with the BACTEC radiometric system (Johnston Laboratories, Towson, Md.). We acidified BACTEC 7H12 medium with buffered phosphoric acid and adjusted the test inoculum to 1/10 of that usually employed in BACTEC protocols; after 5 days of growth we correctly identified 36 of 36 strains susceptible to 50 micrograms of pyrazinamide per ml. All 18 resistant strains were classified as pyrazinamide resistant. (Susceptibility or resistance had been determined by standard plate assays.) The test was able to detect small resistant populations in artificial mixtures of 1 or 2% resistant bacteria with a susceptible strain (10 mixtures each). We tested 70 M. tuberculosis strains in acidified BACTEC 7H12 medium and by the plate dilution test at pH 5.5. All strains grew in the BACTEC medium, but three strains failed to grow on plates and were not tested further; the results of both methods agreed for the remaining strains.
结核分枝杆菌的吡嗪酰胺药敏试验需要酸性环境。通过控制酸化方法以及接种物的质量和数量，可使用BACTEC放射测量系统（约翰斯顿实验室，马里兰州陶森）进行该试验。我们用缓冲磷酸对BACTEC 7H12培养基进行酸化，并将试验接种物调整为BACTEC方案中通常使用量的1/10；培养5天后，我们正确鉴定出36株对每毫升50微克吡嗪酰胺敏感的菌株中的36株。所有18株耐药菌株均被判定为对吡嗪酰胺耐药。（药敏或耐药情况已通过标准平板试验确定。）该试验能够在含1%或2%耐药菌与敏感菌株的人工混合菌液中检测到少量耐药菌群体（每种混合菌液10份）。我们在酸化的BACTEC 7H12培养基中以及在pH 5.5条件下通过平板稀释试验对70株结核分枝杆菌菌株进行了检测。所有菌株在BACTEC培养基中均生长，但有3株在平板上未生长，未作进一步检测；其余菌株两种方法的结果一致。
