刃天青显色法测定氟喹诺酮对结核杆菌的最小抑菌浓度

Rapid determination of MICs of fluoroquinolones for mycobacterium tuberculosis by resazurin colorimetric assay

目的:用刃天青显色法快速测定4种氟喹诺酮对结核分枝杆菌的最小抑菌浓度(MIC),探讨不同氟喹诺酮对结核分枝杆菌的作用和可能的交叉耐药性。方法:用65株对氧氟沙星敏感的菌株(包括42株MDR-TB)和60株氧氟沙星耐药的菌株为试验菌株,在96孔酶标板中,用Middle brook 7H9液体培养基将药物进行连续对倍稀释后,加入一定浓度菌液,用显色法测定MIC。结果:氧氟沙星通过ROC曲线分析所确定的折点浓度为2μg/ml,敏感度为98.3%,特异度为96.9%,准确度为97.6%。加替沙星和莫西沙星对结核分枝杆菌的MIC50和MIC90比氧氟沙星、环丙沙星要低4～8倍,具有比氧氟沙星和环丙沙星更好的抗结核分枝杆菌活性。结论:新一代氟喹诺酮加替沙星和莫西沙星具有比第3代氟喹诺酮氧氟沙星和环丙沙星更低的MIC,更好的抗菌活性,有可能用于低度氧氟沙星耐药MDR-TB的治疗。

Objective：To determine four fluoroquinolones＇ MICs for Mycobaterium tuberculosis by resazurin colometric assay and understand effects and cross resistance of fluoroquinolones on mycobacterium tuberculosis.Method：MICs of 65 Ofloxacin-susceptible Mycobacterium tuberculosis strains and 60 Ofloxacin-resistant clinical isolates were detected in Middlebrook 7H9 liquid medium in 96-well plates by resazurin colometric assay.The proportion method on L-J medium was used as a gold standard,breakpoint concentration of Ofloxacin were determined by ROC curve analysis.Result：The best breakpoint value of drug susceptibility testing of Ofloxacin was 2μg/ml,sensitivity was 98.3%,specificity was 96.9% and accuracy was 97.6%.MIC50 and MIC90 of Gatifloxacin and Moxifloxacin for Mycobaterium tuberculosis were lower 4-8 times than those of Ofloxacin and Ciprofloxacin.Conclusion：Newer fluoroquinolones such as Moxifloxacin,Gatifloxacin may be used to treat low degree Ofloxacin-resistant MDR-TB.