纳米银水凝胶涂膜干预气管导管表面铜绿假单胞菌黏附及生物膜形成的实验研究

目的研究纳米银水凝胶涂膜对气管导管（endotracheal tube，ETT）表面铜绿假单胞菌粘附及细菌生物膜（biofilm，BF）形成的干预作用。方法实验共设6组，分别为空白对照组，涂纳米银3．5、7．0、10．5、14．0和17．5μg／cm^2组。参考Brown平板法，制备ETT、表面铜绿假单胞菌BF模型。通过超声振荡-平板菌落计数法检测体外培养6、12、18h时各组ETT表面BF中的活细菌粘附数量。借助激光共聚焦显微镜观察BF中的活死菌分布情况，并测量BF厚度。结果（1）与空白对照组相比，最小量涂膜组（3．5μg／cm^2）体外培养6h时，导管表面活细菌的粘附量显著减少（P〈0．05），12h时差异无显著性（P〉0．05）；最大量涂膜组（17．5μg／cm^2）体外培养6h时，ETT表面几乎未见细菌粘附（P〈0．05），18h时BF中的活菌数量及BF厚度均显著减少（P〈0．05）。（2）激光共聚焦显微镜观察可见，培养6h时，空白对照组ETT表面粘附的死活菌呈不规则散点样分布，未见明显的细菌菌落形成，而各实验组ETT表面仅有细菌零星分布，其数量少于空白组。18h时空白对照组表面可见大量活死菌堆积粘连，有小菌落形成并相互交通成地图状，可见典型BF结构，而此时最大量涂膜组（17．5μg／cm^2）表面仅见数量不等的菌落形成，菌落周围可见数量不等的细菌分布。结论纳米银水凝胶涂膜可有效减少ETT表面铜绿假单胞菌的粘附数量，延缓导管表面细菌BF形成，其作用强弱随培养时间及单位面积中的纳米银剂量的变化而变化。

Effect of nanosilver hydrogel-coated endotracheal tubes on the adhesion and biofilm formation of Pseudomonas aeruginosa

Objective To evaluate the influence of nanosilver hydrogel-coated endotracheal tube （SCETT） on adhesion and biofilm formation of Pseudomonas aeruginosa on its surface, in vitro. Method The biofilm model of Pseudomonas aeruginosa was prepared with standard ETT and SCETT, incubated with Pseudomonas aeruginosa for 18 hours. The viable bacteria adhered on the surface of ETT were quantified by the standard microbiological method of plate culture count and the distribution of all adhered bacteria and the thickness of biofilm were observed by laser scanning confocal microscopy （CLSM）. Result （ 1 ） Compared with the standard ETT, the quantities of viable bacteria adhered on the SCETT with 3.5 μg/cm^2 was sharply lower at 6 h （ P 〈 0.05）, and no statistical difference was observed at 12 h （ P 〉 0.05 ）. While, at the three time points,the quantities of viable bacteria adhered on the SCETT with 17.5 μg/cm^2 were always statistically lower than on the standard ETT （ P 〈 0.05 ）. And at 18 h ,the thickness of biofilm on the SCETT with 17.5 μg/cm^2 was stasticaUy lower than on the standard ETr. （ P 〈 0.05 ）. （2） At 6 h, all bacteria adhered on the standard ETr scattered irregularly and no bacterial colonies were observed. And the quantities of adhered bacteria on SCETT were all less than on the standard ETT. At 18 h,mueh bacteria and colonies appeared on the standard ETT and linked with each other like a map, But there were only trifle colonies on the SCETr with 17.5 μg/cm^2. Conclusion These results suggest that the nanosilver hydrogel coating of ETT may reduce the bacteria adhesion and retard the biofilm formation on its surface in vitro. This effect of reduced bacterial burden was related with incubation time and nanosilver dose on per area. Based on these results, animal study will be planned to assess the efficacy, safety and feasibility of this method.