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目的:研究穿心莲内酯对铜绿假单胞菌外排泵MexAB-OprM的作用及其机制。方法:采用实时荧光定量PCR分别检测PAO1和MexAB-OprM过度表达株Mex1、Mex2、Mex3培养3h及加入穿心莲内酯0,100,200mg·L-1再培养6h的MexB基因表达量。采用Mueller-Hinton倍比稀释法,检测头孢他啶、头孢匹罗、氯霉素、左氧氟沙星、卡那霉素、依米配能、美罗培南对上述菌株的最小抑菌浓度(MIC)。结果:培养9h与3h相比,PAO1、Mex1、Mex2、Mex3的MexB表达量显著升高,P值分别为0.031,0.027,0.030,0.012。穿心莲内酯100,200mg·L-1组与对照组相比,头孢他啶、头孢匹罗、左氧氟沙星、美罗培南对PAO1、Mex1、Mex2、Mex3株菌的MIC分别降低50%,75%,75%和50%～75%,而对PAO1株QS信号分子C4-HSL的分泌差异无显著性。结论:外排泵MexAB-OprM主要在稳定生长期表达,穿心莲内酯对铜绿假单胞菌外排泵MexAB-OprM转录表达的抑制作用使其可恢复部分抗菌药物的敏感性,而这种作用并非通过抑制C4-HSL的分泌而实现。
Objective: To investigate the effect and mechanism of andrographolide on MexAB-OprM efflux pump of Pseudomonas aeruginosa. Methods: MexB gene expression in Mex1, Mex2 and Mex3 overexpressing PAO1 and MexAB-OprM were detected by real-time fluorescence quantitative polymerase chain reaction (RT-PCR) for 3 h and 0, 100 and 200 mg · L-1, respectively. The minimum inhibitory concentration (MIC) of ceftazidime, cefpirome, chloramphenicol, levofloxacin, kanamycin, emmetrexate and meropenem against these strains was determined by Mueller-Hinton dilution ratio method. Results: Compared with 3h, the expression of MexB in PAO1, Mex1, Mex2 and Mex3 increased significantly at 9h and P values were 0.031, 0.027, 0.030 and 0.012, respectively. The MICs of andrographolide 100, 200 mg · L-1 groups were 50%, 75%, 75% and 50% lower than those of the control group, respectively, for ceftazidime, cefpirome, levofloxacin and meropenem against PAO1, Mex1, Mex2 and Mex3 strains % ~ 75%, while there was no significant difference in the secretion of QS signal molecule C4-HSL from PAO1 strain. CONCLUSION: MexAB-OprM efflux pump is mainly expressed in stable growth phase. The inhibitory effect of andrographolide on the transcriptional expression of MexAB-OprM in efflux pump of Pseudomonas aeruginosa makes it possible to restore the sensitivity of some antimicrobial agents. Not by inhibiting C4-HSL secretion and achieve.