细菌生物膜在急性中耳炎大鼠中耳腔的形成特点及意义

目的 通过观察细菌生物膜在急性中耳炎大鼠中耳腔的形成特点,分析其与急性中耳炎的关系,并探讨该中耳炎模型用于细菌生物膜研究的可行性.方法 30只健康雄性SD大鼠,采用随机数字表法分为实验组(24只)和对照组(6只).麻醉后将50μl肺炎链球菌悬液[1×108菌落形成单位(colony forming unit,CFU)/...

Feature and significance of bacterial biofilm formation in middle-ear mucosa in the rat model of acute otitis media

Objective To investigate the relationship between bacterial biofilm and acute otitis media by observing the feature of bacterial biofilm formation in middle-ear mucosa in the rat model of acute otitis media and to study thc possibility of application this rat model in bacterial biofilm research. Methods A total of 30 healthy, male SD rats were studied,24 animals served as experimental group were bilaterally injected with 50 μl of Streptococcus pneumoniae suspension ( 1 × 108 CFU/ml) via a transbullar approach into the middle ear cavity after anesthesia and six animals were bilaterally inoculated equivalent saline account for control group. At day 1,3, 5, 7, 10 and 14 after inoculation, bilateral middle-ear mucosal specimens were collected from three infected animals and one control animal for scanning electron microscopy (SME).Membranoid substance attached the bilateral middle ear mucosa were collected under the microscope from the other one infected animals, which were prepared for confocal laser scanning microscope (CLSM) with immunofluorescence in situ labeling technique and light microscopy using Gram staining. Results At the early stage of infection( 1 day, 3 days), lots of bacterial adhesion, permanent planting in the local regions of the middle ear cavity and microcolonies formation were found, with mixed phagocytic cells, showing a primary bacterial biofilms formation. In the middle term of infection ( 5 days, 7 days), mature bacterial biofilm scattered on the mucosal surface, formed characteristic three-dimensional structure of "mushroom-shaped"towers. At the late inflammatory period (10 days, 14 days), the bacterial biofilms presented signs of recession. CLSM with FITC-ConA and PI double staining in situ labeling and light microscopy using Gram staining indicated that bacteria and polysaccharide matrix within the biofilms were viable. Conclusions These preliminary findings provide evidence that bacterial biofilms form at the early phase of acute middle ear infection and it may be an important factor in the development of recurrent or persistent otitis media. The rat model of AOM established in this study may be an ideal animal model facilitating the bacterial biofilms research.