agr系统在单核增生细胞李斯特菌耐药及生物被膜形成中的作用

Role of agr System in the Antimicrobial Resistance and Biofilm Formation of Listeria monocytogenes

研究agr系统在单核增生细胞李斯特菌(Lm)对不同抗菌剂耐药及生物被膜形成中的作用。构建agr基因缺失突变株,测定突变株对抗菌药物的敏感性;微孔板定量法检测Lm在不同温度下生物被膜的形成量并利用倒置显微镜观察生物被膜结构;采用软平板法测定细菌的群集及泳动运动能力;通过实时荧光定量PCR检测运动相关基因的转录水平。缺失agr系统导致Lm对头孢噻肟、环丙沙星及苯扎氯铵的耐药性降低。与野生株EGD-e相比,突变株在37℃、20℃以及4℃条件下生物被膜形成量均明显降低;?agrC的群集运动能力增强。RT-qPCR结果显示,缺失agr系统后flaA的转录水平下降。agr系统参与Lm耐药及生物被膜的形成。

This work aims to investigate the role of agr system in antimicrobial resistance and biofilm formation of Listeria monocytogenes(Lm).Gene deletion mutants of agr system were constructed and antimicrobial susceptibility of the mutants was determined.The microplate method was used to measure the biofilm biomass at different temperature,and the inverted microscope was applied to observe the biofilm structure.Plate migration method was to investigate the swimming and swarming motilities of strains.RT-qPCR was adapted to detect the relative expressions of motility-associated genes.Reduced antimicrobial resistances to cefotaxime,ciprofloxacin and benzalkonium chloride were observed in the agr deletion mutants.Compared with the wild type EGD-e,the mutant strains showed decreasing biofilm biomass at 37℃,20℃and 4℃;and increased swarming motility was observed in ?agrC.Results from RT-qPCR showed that the transcription level of flaA in the agr deletion mutants decreased.agr system is involved in antimicrobial resistance and biofilm formation of L.monocytogenes.