【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。更多还原

【Abstract】 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 (Mex1、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 separately.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 andrographolide..CONCLUSION MexAB-OprM efflux pump was mainly transcribed in stationary growth phases.The effect of andrographolide on inhibiting the transcriptional expression of MexAB-OprM might contribute to recover several antibiotics susceptibility in Pseudomonas aeruginosa.However,this effect should not depend on inhibition of C4-HSL secretion.更多还原