大鼠急性中耳炎动物模型的建立

A rat model of acute otitis media

目的建立大鼠急性中耳炎模型并探讨其应用价值。方法 36只健康雄性SD大鼠,麻醉后将50μl肺炎链球菌悬液(1×108CFU/ml)经听泡穿刺注入到大鼠左侧中耳腔(实验耳),右侧注入等量生理盐水(对照耳),分别于注入后1、3、5、7、10、14天各取6只大鼠,行鼓室声导抗测试,手术显微镜下观察鼓膜及中耳腔,中耳腔分泌物或灌洗液细菌培养鉴定,中耳黏膜骨壁HE染色切片检查,动态观察大鼠中耳炎的病理变化及病程转归。结果实验耳注入肺炎链球菌后,感染早期(1天、3天)为急性化脓期,见鼓膜充血,中耳黏膜部分坏死脱落,中耳腔蓄积以中性粒细胞浸润为主的大量炎性渗出物;感染中期(5天、7天)急性化脓性炎症减退,以淋巴细胞、浆细胞浸润为主,黏膜肉芽及纤维增生,中耳积液细菌培养阳性率100%;感染后期(10天、14天)部分实验耳鼓膜色泽恢复正常,听泡内脓液消失,但各有部分耳(2/6耳)转归成分泌性中耳炎表现。结论本研究建立了急性中耳炎的大鼠模型,成功率100%,是研究人类中耳炎较为理想的动物模型,不仅可用于急性化脓性中耳炎的研究,也可用于急性分泌性中耳炎的研究。

Objective To establish a rat model of acute otitis media and to evaluate its value of application. Methods A total of 36 healthy, male SD rats were used. Under anesthesia, the left middle ear cavity （experiment ear） was inoculated via transbullar injection of 50 μl streptococcus pneumoniae suspension （1 × 108 CFU / ml） and the right middle ear cavity （control ear） inoculated with equivalent saline. Following inoculation, development of otitis media and pathological changes were monitored by tympanometry, microscopy, culture and HE staining on Days 1, 3, 5, 7, 10 and 14 （6 rats per each time point）. Results Along with time, infection developed in the tympanic membrane and middle ear cavity in experiment ears. On Day 1 and 3, acute purulent otitis media with tympanic membrane hyperemia, middle ear mucosa necrosis and excessive inflammatory exudation （mainly neutrophil infiltration） was seen. On Day 5 and 7, acute purulent inflammation had been replaced by infiltration of lymphocytes and plasma cells, granulation and fibrogenesis. Middle ear culture was positive in all ears. On Day 10 and 14, a few animals had recovered to normal and some ears （2 / 6 ears） showed secretory otitis media. Conclusions The study demonstrates that streptococcus pneumoniae inoculation can result in middle ear infection, with similar pathological changes and disease course as humans. This appears to be a useful animal model for acute otitis media research. It may be useful not only for studying acute purulent otitis media but also a-cute secretory otitis media.