MTT法在抗真菌药敏实验中的应用

目的：研究MTT法在抗真菌药敏实验中的应用。方法：采用美国临床实验室标准化委员会(NCCLS)推荐方案测定两性霉素B和伊曲康唑对5种常见真菌(白色念珠菌、光滑念珠菌、季也蒙念珠菌、申克孢子丝菌和石膏样小孢子癣菌)的最低抑菌浓度(MIC)，终点判定分别采用NCCLS推荐的直接观察法和MTT法，对两法进行比较。结果：MTT法与常规直接观察法进行MIC终点判定所得结果具有很好的一致性。MTT法测得的A值与接种菌量具有正相关性。两性霉素B与伊曲康唑对丝状真菌和念珠菌都具有很好的抑制作用，MTT法测得的A值随药物浓度的增加而显降低。结论：MTT法较之常规直接观察法结果更为客观、准确，且可量化，因而可以很好的替代肉眼观察法来判定真菌药敏试验的终点。

Study of MTT assay for antifungal susceptibility testing

Aim: To study MTT assay in the application of antifungal susceptibility testing. Methods: antifungal susceptibility testing of amphotericin B and Itraconazole for 5 normal fungal strains (C. albicans, S. schenckii, C.glabrata, C.guiliermondii and T.gupseum) were performed by reference method of National Committee for Clinical Laboratory Standard (NCCLS). The minimum inhibitory concentration (MIC) were determined by MTT assay and routine direct observing assay separately. These MIC values from two assay were compared with each other. Results: The MTT assay and routine direct observing to determine endpoint are good identical. The A values of MTT assay has good correlativity with numbers of viable fungi. The results showed that the fungi were inhibited significantly in the presence of Amphotericin B or Itraconazole. The A values of MTT assay decreased asg the increase of the concentration of antifungal drugs. Conclusion: MTT assay is more objective, more precise than routine direct observing, then it can replace routine direct observing assay to determine antifungal endpoint.