白色假丝酵母菌耐药性与耐药基因表达及蛋白酶的关系

Relationship between drug resistance of Candida albicans,gene expression associated with drug resistance and proteinase

目的研究呼吸道白色假丝酵母菌耐药性与耐药相关基因表达及细胞外蛋白水解酶的关系。方法用NCCLSM27-A方案中的微量液基稀释法检测99株呼吸道分离的白色假丝酵母菌对氟康唑和伊曲康唑的最小抑菌浓度(MIC),RT-PCR半定量检测耐药相关基因CDR1和MDR1的表达,牛血清清蛋白平板法检测细胞性蛋白酶活力。结果99株菌对氟康唑的耐药率为4%,对伊曲康唑的耐药率为12.1%,CDR1的表达在氟康唑的剂量依赖性敏感组高于敏感组和耐药组(P<0.05),蛋白酶的活力在氟康唑剂量依赖性敏感组高于敏感组(P<0.05)。结论菌株的耐药性除与CDR1的过表达有关外,还与其他耐药机制有关,耐药程度不同的菌株细胞性蛋白酶活力有差别,提示菌株的耐药性与毒力之间可能有关联。

Objective To study the relationship between drug resistance and expression of the gene associated with drug resistance in Candida albicans, as well as the secretory proteinase activity of these isolates. Methods The minimum inhibitory concentrations （MIC） to fouconzole and itraconazole in 99 strains of Candida albicans isolated from respiratory tract were measured by broth microdilution method, the M27-A protocol recommended by NCCLS. The gene expressions of CDR1 and MDR1 were semi-quantitatively determined by RT-RCR. The secretory proteinase activity of these isolates was assayed by plate with medium containing bovine serum albumin. Results The rates of drug resistance to fluconzole and itraconazole were 4% and 12.1% respectively. CDR1 expression in the susceptible dose-dependent （S-DD） isolates was higher than those in the susceptible isolates and drug-resistant isolates （ P 〈 0.05 ）. The secretory proteinase activity of the S-DD isolates was higher than that of susceptible isolates （ P 〈 0.05 ）. Conclusions The drug resistance in Candida albicans strains was not only associated with the overexpression of CDR1 ,but also with other factors. The fact that the isolates with different drug resistance showed differences of secretory proteinase activity suggested there might be some relationship between drug resistance and virulence of the isolates.