多尼培南对铜绿假单胞菌生物被膜形成和群体感应系统的影响

Effect of Doripenem on Pseudomonas aeruginosa Biofilm Formation and the Quorum Sensing System

目的:探究新型碳青霉烯类抗生素多尼培南(doripenem,DOR)对临床分离铜绿假单胞菌生物被膜形成的抑制作用,及对其群体感应系统相关基因Las R、Rhl R、Pqs A、Pqs E、Pqs R表达量的影响。方法:用结晶紫染色法测定30株临床分离铜绿假单胞菌形成生物被膜能力和多尼培南对生物被膜形成的抑制作用;微量肉汤稀释法测定最低抑菌浓度(minimal inhibitory concentration,MIC)和最低抑制生物被膜浓度(minimal biofilm inhibitory concentration,MBIC);活菌计数法绘制多尼培南对生物被膜内细菌的杀菌曲线;采用实时定量荧光PCR(real-time PCR)法测定多尼培南对群体感应(quorum-sensing,QS)系统相关基因表达量的影响。结果 :30株铜绿假单胞菌中的29株(97%)形成生物被膜;多尼培南具有较强的抗铜绿假单胞菌浮游菌和生物被膜抑制活性,MICR为0.5~1μg·m L-1,MBICR为1~4μg·m L-1;显著下调Las R、Rhl R、Pqs A、Pqs E、Pqs R的表达量。结论:临床分离铜绿假单胞菌具有高生物被膜形成率,多尼培南对铜绿假单胞菌生物被膜具有抑制作用,可能与其下调QS系统相关基因有关。

Objective: To study the activity of doripenem, a novel carbapenem, against clinical Pseudomonas aeruginosa biofilm and its effects on the expression of Las R, Rhl R, Pqs A, Pqs E and Pqs R genes expression in quorum sensing system(QS). Methods: Biofilm-forming strains were screened from 30 clinical P. aeruginosa using a modified crystal violet staining method. Minimal inhibitory concentration(MIC)and minimum biofilm inhibitory concentration(MBIC) were determined by micro-broth dilution. Time-kill analysis was performed by viable count. The effect of doripenem on the QS system was assessed with RTPCR testing the expression of related genes. Results: Their were 29 strains among the 30 clinical P.aeruginosa showed biofilm-forming ability. Doripenem inhibited both planktonic and biofilm-forming bacteria. The ranges of MIC and MBIC were 0.5-1 μg·m L-1and 1-4 μg·m L-1, respectively. Doripenem down-regulated significantly the expressions of Las R, Rhl R, Pqs A, Pqs E and Pqs R. Conclusion: Most clinical P.aeruginosa can form biofilm. Doripenem can inhibit biofilms of P. aeruginosa, which may be related to the down-regulated expression of QS genes.