绵羊肺源性致病性大肠杆菌的分离与鉴定

Isolation and identification of pathogenic Escherichia coli from sheep lung

【目的】近年来,羊呼吸系统疾病日益频发,由肠外致病性大肠杆菌感染引起的呼吸道疾病也日渐增多,给养羊业带来了一定经济损失。本文旨在确定新疆石河子地区某羊场表现为呼吸道感染症状的病死羔羊的细菌性病原及其特性。【方法】采用细菌常规分离鉴定结合16S rRNA基因序列分析的方法从发病羔羊的肺脏中分离鉴定细菌,并对分离株进行药敏试验、特异基因PCR检测、小鼠致病性试验及肺脏组织的病理学观察。【结果】从病死羔羊肺脏组织分离得到一株致病性大肠杆菌,该分离株呈多重耐药现象,检测到iutA、fyuA和ireA三种毒力基因;病变肺脏肺泡壁毛细血管充血,界限不清,支气管管腔充血,周围淋巴细胞浸润、增生。【结论】从病死羔羊肺中分离的细菌性病原是肠外致病性大肠杆菌(ExPEC)。

[Objective] In recent years, more and more reported sheep respiratory diseases are partially caused by ExPEC（Extraintestinal pathogenic Escherichia coli）, resulting in some economic losses. We determine and characterize the bacterial pathogen from sheep with respiratory tract infection in Shihezi, Xinjiang. [Methods] Bacteria were isolated and identified from the lungs of infected lambs by routine methods combined with 16S rRNA gene sequence analysis. Meanwhile, antimicrobial susceptibility and specific virulence gene of the isolates were tested with K-B and PCR. Pathological examination was carried out from the lung of naturally infected sheep and artificially infected mice. [Results] A pathogenic Escherichia coli was isolated from infected lamb lung, which showed multiple drug resistance and carried 3 virulence genes（iutA, fyuA and ireA）. Histology examination showed that the capillary vessel of alveolar wall was congested, bronchial lumen was found hyperemia, infiltration and hyperplasia of lymphocyte could be seen in lung tissue. [Conclusion] The bacterial pathogen isolated from infected lambs was ExPEC.