超声对金黄色葡萄球菌生物膜的体外破坏作用

In vitro destructive effect of ultrasound on Staphylococcus aureus biofilms

背景:有研究表明,超声增强抗生素杀菌能力的效力表现为强度依赖性,即超声强度越高其效力越大。目的:观察不同强度超声对金黄色葡萄球菌及其生物膜的破坏作用。方法:采用引导片培养法体外培养金黄色葡萄球菌生物膜,分为3组干预,对照组不作任何处理;低强度超声组采用强度为500 m W/cm、频率为200 k Hz的脉冲超声波干预10 min;高强度超声组采用强度为40 W、频率1 MHz的连续超声波干预10 min。采用超声振荡-活菌计数法计数细菌菌落;采用碘化丙啶(PI)和FITC-Con A分别标记细菌DNA和多糖,激光扫描共聚焦显微镜检测生物膜成型情况。结果与结论:高强度超声组细菌菌落低于对照组、低强度超声组(P<0.05),后两组间细菌菌落比较差异无显著性意义。低强度超声组红色荧光和绿色荧光的数量及密集程度与对照组无明显区别,高强度超声组的红色荧光和绿色荧光相对于前两组有明显减少。表明低强度超声不能杀灭细菌且对细菌生物膜的破坏作用微小,高强度超声能有效杀灭细菌,并且对细菌生物膜具有显著破坏作用。

BACKGROUND： Studies have shown that the ultrasound enhances the on bactericidal activity of antibiotics in an intensity-dependent manner, that is, the higher the ultrasound intensity, the greater its effectiveness. OBJECTIVE： To study the destructive effect of different intensities of ultrasound on Staphylococcus aureus and its biofilm. METHODS： Staphylococcus aureus biofilms were cultured in vitro using guide sheet culture method and divided into three groups for intervention. The biofilm in the control group received no treatment. The biofilm in the low-intensity ultrasound group was intervened by pulsed ultrasound with an intensity of 500 m W/cm and frequency of 200 k Hz for 10 minutes. The biofilm in the high-intensity ultrasound group was intervened by continuous ultalsound with an intensity of 40 W and frequency of 1 MHz for 10 minutes. Bacterial colonies were counted using ultrasonic oscillation-live bacteria counting method. DNA and polysaccharide of the bacteria wererespectively marked using propidium iodide and FITC-Con A. The molding of the bilfilm was determined using laser scanning confocal microscope. RESULTS AND CONCLUSION： The number of bacterial colonies in the high-intensity ultrasound group were lower than that in the control and low-intensity ultrasound groups（P 〈0.05）, and there were no significant differences between control and low-intensity ultrasound groups. There were no significant differences in the number and intensity of red fluorescence and green fluorescence between low-intensity ultrasound and control groups; however, the number and intensity of red fluorescence and green fluorescence in the high-intensity ultrasound group were significantly decreased compared with the low-intensity ultrasound and control groups. These results demonstrate that the low-intensity ultrasound cannot kill the bacteria and it has a tiny destructive effect on the biofilm of bacteria; however, the high-intensity ultrasound can effectively kill the bacteria and has a strong destructive effect on the bilfilm of bacteria.