论文部分内容阅读
目的 试图通过产毒性大肠杆菌 (ETEC)对豚鼠致病性的实验研究 ,进一步探讨该菌的致病机理。方法 利用人源性ETEC菌株E44 813、E44 815、E44 82 2和E44 82 3攻击豚鼠 ,造成豚鼠ETEC感染模型 ,观察豚鼠ETEC感染的病变特点。结果 4株ETEC菌株均能造成豚鼠发病 ,以E44 813致病性最大。ETEC能定植于豚鼠肠道至少达 14天。发病豚鼠肠道明显充血、肿胀 ,以回肠为最严重。感染组无发病症状的豚鼠也有 5 /12出现空肠和回肠轻度肿胀。光镜下发病动物肠粘膜组织结构大致完整 ,但有较明显的病理改变 ,特别是空肠和回肠 ,主要表现为水肿、淋巴细胞浸润和充血 ,病变部位可见于空肠和回肠肠组织各层。病变程度与症状严重程度相关 ,感染组 9/12无症状豚鼠也有显微病理改变 ,但较轻。超微结构观察显示发病动物空肠和回肠上皮细胞部分变性 ,细胞内未见细菌入侵。结论 ETEC不仅影响小肠上皮细胞的分泌和吸收功能 ,还能导致豚鼠小肠组织广泛的以水肿为主的明显的炎症反应和细胞变性
OBJECTIVE: To investigate the pathogenicity of guinea pigs by producing viable enterotoxigenic Escherichia coli (ETEC) and to explore the pathogenic mechanism of this strain. Methods The human ETEC strains E44 813, E44 815, E44 82 2 and E44 82 3 were challenged with guinea pigs to induce ETEC infection in guinea pigs. The pathological changes of ETEC in guinea pigs were observed. Results All four ETEC strains could cause the onset of the disease in guinea pigs, with the highest pathogenicity of E44 813. ETEC colonizes guinea pig intestines for at least 14 days. The incidence of guinea pig intestinal congestion, swelling, the most serious ileum. In the infected group, there were 5/12 mild swelling of the jejunum and ileum in guinea pigs with no symptoms. Under light microscope, the histological structure of intestinal mucosa was almost intact, but there were obvious pathological changes, especially jejunum and ileum. The main manifestations were edema, lymphocyte infiltration and congestion, and the lesion was found in the layers of jejunum and ileum. The severity of the disease was related to the severity of the symptoms. The 9/12 asymptomatic guinea pigs in the infected group also had microscopic pathology but were lighter. Ultrastructural observation showed that the animals were jejunal and ileal epithelial cells partially degenerated, and no bacterial invasion occurred in the cells. Conclusion ETEC not only affects the secretion and absorption of intestinal epithelial cells, but also leads to a wide range of obvious inflammatory reactions and cell degeneration