阿奇霉素对铜绿假单胞菌生物被膜和毒力因子的干预作用

目的 研究阿奇霉素对铜绿假单胞菌生物被膜形成及毒力因子分泌的干预作用.方法 2倍稀释法测定最低抑菌浓度(MIC);结晶紫染色法测定早期黏附;建立PAO1体外生物被膜模型;扫描电镜观察生物被膜形态;连续稀释法进行活菌计数;弹性蛋白-刚果红法测定弹性蛋白酶活性;偶氮酪蛋白法测定蛋白水解酶活性;氯仿萃取法测定绿脓菌素;苔黑酚法测定鼠李糖脂.结果 PAO1阿奇霉素组对载体的黏附低于PAO1空白对照组(P＜0.05);第3、7天PAO1阿奇霉素组生物被膜少于PAO1空白对照组,且载体活菌计数少于PAO1空白对照组(P＜0.05).PAO1阿奇霉素组弹性蛋白酶活性、蛋白水解酶活性、绿脓菌素浓度、鼠李糖脂浓度均明显低于PAO1空白对照组(P＜0.01),弹性蛋白酶活性及绿脓菌素浓度与PA-JP3株组相当(P＞0.05),而蛋白水解酶活性及鼠李糖脂浓度高于PA-JP3株组(P＜0.05).结论 阿奇霉素可以抑制铜绿假单胞菌的黏附及其生物被膜的形成,并可以抑制其毒力因子的释放.

Intervention of azithromycin on Pseudomonas aeruginosa biofilm and virulence factors

Objective To evaluate the effect of azithromycin on Pseudomonas aeruginosa PAO1 biofilm formation and virulence factors production. Methods Detect the minimum inhibitory concentration of azithromycin against PAO1 by 2-fold dilution method. Crystal violet staining assay was used for initial adhesion assays. The PAO1 biofilm was established in vitro and observed by scanning electron microscope. Viable bacterial counts were determined by serial dilution. LasB elastolytic activity was determined by using Elastin-Congo Red. Protease activity was determined by Azo-casein. Chloroform extraction method was used for pyoverdine assay . The orcinol assay was used to directly assess the amount of rhamnolipids . Results Scanning electron microscope biofilm and viable bacterial counts of PAO1 adhered to the surface of catheter in PAO1 azithromycin group were less than the PAO1 control group after incubated for 3 d and 7 d ( P ＜0.05), and the initial adhesion was weaker ( P ＜ 0. 05 ). The virulence factors production were obviously decreased (P ＜0.01 ). LasB elastolytic activity and pyoverdine were even reduced to the same as with the PA-JP3 group ( P ＞ 0.05 ), but the protease activity and the rhamnolipids concentration were higher than the PA-JP3 group ( P ＜ 0.05 ). Conclusion Azithromycin can inhibit PAO1 bioflim formation in vitro and virulence factors production.