中文摘要：

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PA01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。

英文摘要：

OBJECTIVE To investigate the effect and mechanism of andrographolide on inhibiting MexAB-OprM efflux pump of Pseudomonas aeruginosa. METHODS The MexB mRNA expressions of PAO1 and MexAB-OprM overexpressing strain （Mexl, Mex2, Mex3） were measured by using real time PCR at 3 h and 9 h after inoculation. In presence of 0,100,200 mg·L^-1 andrographolide, the minimal inhibitory concentration（MIC） of CAZ, CPR, CP, L-OFLX, KM, IPM, MER to those strains was detected by using Mueller-Hinton broth dilution. The effect of andrographolide on quorum sensing signal C4- HSL in PAO1 strain was also determined by a sensor strain. RESULTS The relative MexB mRNA amount of PAO1 and Mex1 ,Mex2,Mex3 cultured for 9 h was significantly higher than those strains cultured for 3 h and P value was 0. 031,0. 027,0. 030,0. 012 sepa rarely. In contrast, the MIC of CAZ,CPR,L-OFLX, MER to those strains in the concentration of 100,200 mg·L^-1 andrographolide also decreased 50%, 75%,75% and 50%-75%, respectively, compared with the control. In addition, no significant difference was observed in the level of C4-HSL secretion in PAO1 strain treated with andrographoiide.. CONCLUSION Mex AB-OprM efflux pump was mainly transcribed in stationary growth phases. The effect of andrograpbolide on inhibiting the transcriptional expression of MexAP-OprM might contribute to recover several antibiotics susceptibility in Pseudomonas aeruginosa. However, this effect should not depend on inhibition of C4-HSL secretion.