表皮葡萄球菌生物膜感染动物模型的建立

Establishment of an animal model for biofilm infection of Staphylococcus epidermidis

表皮葡萄球菌是引起医院内感染的常见条件致病菌之一,可在植入性医疗材料表面形成生物膜而引起慢性持续性感染。为建立表皮葡萄球菌生物膜感染动物模型,选取新西兰白兔、樱桃谷鸭、豚鼠、C57小鼠、BALB/c小鼠和Sprague-Dawley(SD)大鼠为受试对象,分别采集血清,在体外检测其对表皮葡萄球菌生物膜的抑制作用,筛选出抑制效应较弱的新西兰白兔用于建立生物膜感染模型。经兔皮下埋植小盘后接种表皮葡萄球菌(1ml,109CFU/ml),72h后用光学显微镜、激光共聚焦显微镜及扫描电子显微镜观察小盘表面生物膜的形态,并进行菌落计数。结果显示,动物模型内形成的生物膜与体外培养的生物膜在形态上相似。进而利用该模型初步研究万古霉素在体内对细菌生物膜形成的影响,结果显示,万古霉素局部给药组生物膜内的活菌数明显低于未处理组(P<0.01)。本研究成功建立了表皮葡萄球菌生物膜感染新西兰白兔模型,可用于研究表皮葡萄球菌在体内形成生物膜的能力及局部药物的抗生物膜效果评价。

Staphylococcus epidermidis （ S. epidermidis ） nosocomial infections. Although it is known that the is one of the common opportunistic pathogens causing bacteria can form biofilms by adhering to indwelling medical devices there is no optimal animal model for in vivo study. To establish an animal model for biofilm infection, the serum samples from several animal species were collected and their inhibitory effects on in vitro S. epidermidis （ATCC RP62A） biofilm formation were observed. New Zealand white rabbit was selected as the leading candidate for its relatively weaker inhibition on biofilm formation. Dishes cut from 96-well plates were sterilized and implanted subcutaneously, followed by injection of 1 ml （109 CFU/ml） bacteria in situ. Biofilms formed on the dishes in the New Zealand white rabbit model after 72 h sharedmorphological similarity with that formed in vitro observed under confocal laser scanning microscope and scanning electron microscope. Furthermore, the effect of vancomycin against S. epidermidis biofilm fomation in vivo was investigated. The results showed that the viable bacterial cells in biofilm treated with vancomycin （8 μg/ml, local injection） was significantly lower （P〈0.01） than that in non-treatment group. The New Zealand white rabbit model for S. epidermidis biofilm formation was established. This model can be used for the observation of biofilm morphology and evaluation of effectiveness of antimicrobial treatment in vivo.