鸡大肠杆菌病形态学与分子生物学的诊断

Diagnosis of chicken colibacillosis by morphological and molecular biological method

为建立鸡大肠杆菌病可靠、实用的诊断方法,取临床疑似大肠杆菌感染病例进行剖检、病理组织观察,对病原进行分离培养、形态观察和16S rDNA序列测定,并通过相似性分析对分离菌株进行鉴定。结果显示,病鸡主要临床表现为肝周炎、心包炎和腹膜炎;肝、心和脾等器官组织有不同程度损伤和炎性病理变化;分离菌株在麦康凯培养基上的菌落呈亮粉红色,镜检为革兰阴性短杆菌,16S rDNA序列与GenBank中大肠杆菌的相似性为98.8%~99.1%。综合临床解剖、病理组织检查和病原鉴定结果,诊断该病为大肠杆菌病。

In order to establish a reliable diagnostic method for chicken colibacillosis, we chose the clinically suspected cases for autopsy and histopathological observation,isolated the dominant microorganism from the epidemic materials, and identified it by morphological observation,16 S r DNA sequence alignment and construction of phylogenetic tree. The sick chicken revealed symptoms of perihepatitis,pericarditis, and peritonitis by autopsy. There were varying degrees of damages and inflammatory pathological changes in theliver, heart and spleen found by means of histopathology.The isolated strain formed light pink colonies on Mac Conkey Agar medium and manifested as a short Gram-negative bacilli under the microscope. 16 S r DNA sequence of the strain had a 98.8%-99.1% similarity compared with that of Escherichia coli in Gen Bank. The colonial and cellular morphology and sequence similarity testify that the isolated strain belonged to E·coli. Based on overall consideration of the evidences in anatomy, histopathology and etiology, we diagnose the case as colibacillosis.