主动外排泵对铜绿假单胞菌摄入硅纳米颗粒的影响研究

Effect of Efflux Pumps on Silica Nanoparticles Uptake by Pseudomonas Aeruginosa

目的探讨主动外排泵对铜绿假单胞菌(PA)摄入硅纳米颗粒的影响,为将其作为药物载体提供实验依据。方法收集中南大学湘雅二医院2007年1—6月检测的PA临床菌株24株,分别编号为S1～S24;以PA的野生菌株PA01作为MexA基因的阳性对照。将筛选出的6株PA临床菌株及野生菌株PA01培养到对数增长期,分别以终浓度为30μg/ml(高浓度组)和终浓度为6μg/ml(低浓度组)的硅纳米颗粒加入到菌液中,培养2、4、8、12、24 h时取样并在电子显微镜下观察硅纳米颗粒摄入情况。结果 24株PA临床菌株菌液中均有不同程度的外排泵基因表达,S24同时表达4种外排泵基因(MexA、MexC、MexX、MexE)。PA01(仅表达1种外排泵基因MexA)与S24摄入的硅纳米颗粒情况相似,PA01菌液培养2 h时可以发现硅纳米颗粒摄入,以12、24 h时硅纳米颗粒摄入最多,且摄入情况相似;高浓度组S24培养24 h时硅纳米颗粒摄入量是低浓度组的2倍。结论硅纳米颗粒不完全受主动外排泵的影响,至少有一部分硅纳米颗粒能进入到细菌体内并持续一段时间,这为其作为抗菌药物载体提供了实验依据。

Objective To investigate the effect of efflux pumps on the uptake of silica nanoparticles by Pseudomonas aeruginosa(P.aeruginosa).Methods A total of 24 strains of P.aeruginosa,labeled as S1 ～ S24,were isolated in the Second Xiangya Hospital of Central South University from January 2007 to June 2007.The wild P.aeruginosa strain PA01 was taken as the positive control of MexA.Six clinical stains of P.aeruginosa and PA01 were cultured to the exponential growth phase.The 30 μg / ml or 6μ g / ml silica nanoparticles were added to the culture medium.The distribution of the silica nanoparticles were examined under electron microscope after 2 h,4 h,8 h,12 h,and 24 h.Results Among the 24 strains of P.aeruginosa,S24 expressed four efflux pump genes at the same time.The uptake amounts of silica nanoparticles were similar between PA01(expressed only 1 efflux pump gene MexA) and S24,the uptake began 2 h later,and the uptake amount was the largest after 12 h and 24 h.The uptake amount of S24 with 30 μg / ml silica nanoparticles was twice as large as that with 6 μg / ml silica nanoparticles after 24 h.Conclusion The silica nanoparticles can be taken by P.aeruginosa,which is almost not influenced by the efflux pumps.At least,some of silica nanoparticles can enter P.aeruginosa freely and stay there for a certain time,which provides some empirical evidence for the silica nanoparticles' potential as an antibiotics vector.