鸭致病性大肠杆菌中耶尔森菌强毒力岛的分子流行病学调查

Molecular epidemiological investigation of Yersinia high-pathogenicity island in duck pathogenic Escherichia coli

为了解耶尔森菌强毒力岛(HPI)在鸭致病性大肠杆菌中的流行情况,根据HPI结构基因irp2和fyuA参考序列设计了引物,用PCR方法对从成都等地分离的64株鸭致病性大肠杆菌和28株健康雏鸭泄殖腔拭子分离的大肠杆菌基因进行了扩增和检测,并对5个菌株相关基因进行了克隆和序列分析.结果表明,irp2和fyuA携带率在鸭大肠杆菌病分离株分别为40.6%(26/64)和39.1%(25/64),在健康鸭泄殖腔大肠杆菌分离株分别25.0%(7/28)和21.4%(6/28).鸭大肠杆菌病分离株携带fyuA和irp2的阳性率显著高于健康鸭大肠杆菌分离株(P<0.05),HPI毒力岛的携带率与菌株的致病性呈明显的正相关.分析表明相关基因与GenBank中参考序列的同源性高达98%以上.

In order to investigate the prevalence of Yersinia high-pathogenicity island（HPI） in duck pathogenic Escherichia coli, two pairs of primers are designed to amplify fragments of the HPI irp2 and fyuA genes respectively according to the reference sequences of these two genes. By using the method of polymerase chain reaction（PCR）, irp2 and fyuA genes are amplified and detected from 64 strains of pathogenic E.coli isolated from ill ducklings in Chengdu area and 28 strains of E.coli isolated from clinically healthy ducklings＇cloaca in same area, in which the relative genes of 5 strains from these isolates are cloned and sequenced. The results show that the carrying rates of irp2 and fyuA genes are 40.6%（26/64） and 39.1%（25/64） respectively in 64 strains of clinical isolates and are 25.0%（7/28） and 21.4%（6/28 ） respectively in 28 strains of cloaca isolates, which showed a significant difference between the clinical isolates and the cloaca isolates, and the HPI carrying rates of former are obviously higher than that of latter（P 〈 0.05）. The results also demonstrate a strong positive correlation between carrying rates of HPI and their pathogenicity. The analytic results show that the homology of relative genes is high above 98% with the reference sequences published in GenBank.