铜绿假单胞菌QS系统对大鼠皮肤溃疡面生物被膜形成的影响

目的 对比野生型铜绿假单胞菌及LasI和RhlI突变株铜绿假单胞菌感染大鼠皮肤溃疡创面后生物被膜形成的差异,探讨铜绿假单胞菌LasI及Rhll基凶在活体生物被膜形成中的作用.方法 制备大鼠皮肤溃疡模型,共60个创面,分成3组,前两组分别接种导人绿色荧光蛋白(GFP)质粒的野牛型铜绿假单胞菌及LasI和RhlI突变株铜绿假单胞菌,另一组不接种细菌作为空白对照组.分别于术后1、3 7 10 d切取标本,每个标本分成两等份,分别进行细菌学检测和光学显微镜及荧光显微镜观察二组上皮化及生物被膜形成情况.结果 除了第7天外,在第1、3、10天感染了野牛型铜绿假单胞菌创而组织内细菌数多于LasI及RhlI缺陷组的细菌数.空白对照组细菌数则更少,且野生组上皮化较慢,生物被膜较厚.结论 活体内LasI及RhlI基因缺损的铜绿假单胞菌生物被膜形成能力及组织感染能力均低于野生株.

The involvement of quorum sensing in the development of biofilm in rat wound infected with pseudomoas aeruginosa

Objective To understand the importance of quorum sensing in chronic Pseudomonas (P.) aeruginosa wound infection,and compare the in vivo pathogenic effects of the wild-type P. Aeruginosa PA01 and its double mutant, PAOI lasI rhll ,in which the signalgenerating parts of the quorum sensing systems are defective. Methods The rat model of P. Aeruginosa wound infection was used in the present study. Partial thickness skin wounds were created. Outline of wound was cut by using 6 mm biopsy punch, 6 wounds created on each animal. Wounds were inoculated with bacterial suspension (0.014 ml) of wildtype P. Aeruginosa PA01 and its double mutant,is placed on the base of the ulcer at a concentration of 5 x 107 cfu/wound. Total 60 wounds are created. On the dayl, day3, day7 and day10 after operation, the samples were cut by using 8 mm biopsy punch respectively. Evenry sample was divided into 2 same parts ,one part was used for bacterial count and the other part was rapidly frozen in liquid nitrogen or imbede by paraffin. The biopsies of wounds were stained with haematoxylin and eosin or Rhodamine-conjugated ConA were observed by light microscope and fluorescence microscope, the formation of epithelization and biofilm were detected. Results The results showed that the mutant biofilm are thin and much more uniform compared to wild-type counterpart. On day7 post-infection evidence re-epithelialization at the double mutant wound bed ;On day1,3,10 bacterial number are minor in the double mutant wounds tissue except on day 7. Condnsion The conclusion of this study is that functional lasl and rhlI genes of P. Aeruginosa play a important roles in the development of biofilms.