中文摘要：

目的建立实时荧光定量PCR法检测铜绿假单胞菌MexAB-OprMmRNA水平的表达，探讨中草药穿心莲内酯对铜绿假单胞菌外排泵MexAB-OprM表达情况的影响。方法克隆铜绿假单胞菌mexAB-oprM操纵元中merB基因和30SrRNA基因rpsL，分别构建相应质粒作为实时荧光定量PCRDNA标准品。以不同浓度穿心莲内酯作用铜绿假单胞菌PA01株，采用实时荧光定量PCR法检测PA01菌株中mexB和rpsl。基冈mRNA的表达水平。结果成功构建标准曲线质粒，50、100、150和200／μg／ml。穿心莲内酯作用后PA01ⅢPTB基因mRNA表达量分别为0．04±0．03、0．06±0．07、0．09±0．03和0．04±0．03，对照组为0．24±0．04，差异有统计学意义（P〈0．05），穿心莲内酯组间差异无统计学意义（P〉0．05）。结论穿心莲内酯可在mRNA水平抑制外排泵Mex—AB-OprM的表达，这可能是其抗感染机制之一。

英文摘要：

Objective To develop a real-time polyrnerase chain reaction（PCR） system to determine transcriptional level of MexAB OprM multidrug efflux pump gene and to investigate the impact of andrographolide on MexAB-OprM gene transcription in Pseudoraonas aeruginosa. Methods The fragments of mexB gene of mexAg-oprM operon and 30S rRNA gene rpsL were amplified and cloned into two plasmids respectively. These plasmids were used as external standards for real-time PCR. Real-time PCR was applied to measure the mRNA transcripition of mexB and rpsL gene in Pseudomonas aeruginosa growing in medium with different concentrations of andrographolide. Results The plasmids for standard curve were constructed successfully. The relative mexB mRNA expressions in 50, 100, 150 and 200 μg/mL andrographolide were 0. 04±0.03, 0.06±0. 07, 0.09±0.03 and 0.04±0.03 respectively, which were significantly lower than that in the control （0.24 ± 0.04, P 〈 0.05）, while no significant difference was found within the andrographolide-treated groups （P 〉 0.05）. Conclusion Andrographolide can reduce the transcriptional level of MexADOprM, which may be one mechanism for its anti-infection effect.