铜绿假单胞菌QS系统缺陷对生物膜形成及大鼠肺部慢性感染的影响

目的研究lasI rhlI基因缺陷对铜绿假单胞菌体外生物膜形成的影响;观察铜绿假单胞菌PAO1野生型及其群体感应系统的lasI rhlI基因缺陷型菌株人工生物膜致病性的差异,了解群感应系统的lasI rhlI基因在铜绿假单胞菌生物膜感染致病过程中的作用。方法采用生理盐水-吸痰管系统进行铜绿假单胞菌体外生物膜的培养,3d后用扫描电子显微镜观察PAO1、PAO1 lasI rhlI形成生物膜的情况。从大鼠支气管内直接予以PA(菌种为铜绿假单胞菌PAO1野生型,PAO1 lasI rhlI基因缺陷型)海藻酸盐微菌粒悬液(1×109CFU/mL)攻击,建立PAO1野生型及QS系统的lasI rhlI基因缺陷型菌株人工生物膜肺部感染动物模型。于感染2周后评估各组大鼠的肺部病理学、细菌学的变化。结果3d后PAO1野生型的生物膜较厚,lasI rhlI基因缺陷型菌株所形成的生物膜结构呈薄膜状,明显薄于PAO1野生型。感染2周后,PAO1野生型组的病理学改变和细菌学改变均显著重于lasI rhlI基因缺陷组(P<0.001)。结论QS系统的lasI和rhlI基因影响铜绿假单胞菌体外形成生物膜的能力,并且在PA肺部感染过程中发挥着重要作用。

Effects of LasI RhlI Defects on P.aeruginosa Biofilm Formation in Vitro and P.aeruginosa Chronic Lung Infection in Rats

Objective To explore the effects of lasI rhlI mutant on P.aeruginosa biofilm formation in vitro and the importance in P.aeruginosa(PA) biofilm lung infection,the pathogenic effects of the wild-type P.aeruginosa PAO1 in vivo were compared with quorum sensing(QS) double mutant PAO1lasI rhlI.Methods Examination of the biofilm developments of PAO1 and lasI rhlI mutant in vitro by means of scanning electronic microscopy(SEM) after three days' incubation.Rats were challenged intratracheally with alginate embedded PA strain PAO1 and the mutatant of QS in the concentration of 1(109 colony-forming units per milliliter(CFU/mL).Two weeks post intratracheal challenge with P.aeruginosa,parameters were evaluated.Results After 3d,PAO1 biofilm was better developed,whereas lasI rhlI mutant bioflm structure is a pellicle-shaped one.Two weeks after challenge,significantly milder microscopic and macroscopic lung pathology(P<0.001) and less bacterial load(P<0.005) were found in the lasI rhlI mutant group compared to the wild type PAO1 group.Conclusion lasI rhlI gene is important in the formation of P.aeruginosa biofilm in vitro.The pathogenic effects of the lasI rhlI mutant were obviously faster to become milder than those of the wild type PAO1 in the infected animal models.The hosts could better clear the PAO1 lasI rhlI mutant compared to PAO1 wild type.The functional lasI and rhlI genes of P.aeruginosa play an important role in the chronic lung infection.