鸡舍内外环境中气载大肠杆菌同源性的分子鉴定

The Homology Molecular Identification of Airborne Escherichia coli Isolated from Indoor and Outdoor Air of Chicken Houses

采用ANDERSEN-6级空气微生物样品收集器和RCS离心式采样器在5个鸡场舍内空气、舍外上风向和下风向不同距离收集气载大肠杆菌;并收集鸡的粪便,分离大肠杆菌。利用大肠杆菌基因间重复一致序列为引物的聚合酶链式反应（ERIC-PCR）分型技术,扩增不同测量点收集的大肠杆菌的DNA图谱。通过每个采样点的大肠杆菌的浓度变化以及大肠杆菌遗传相似性分析确认动物舍微生物气溶胶向舍外环境的传播。结果显示：5个鸡舍内空气中大肠杆菌的浓度远远高于舍外上风和下风向的大肠杆菌浓度（P〈0.05或P〈0.01）,但是舍外不同距离间的大肠杆菌浓度差异并不显著（P〉0.05）。同样,ERIC-PCR结果表明,从鸡的粪便中分离的大肠杆菌与从舍内空气中分离的部分大肠杆菌（34.1%）,以及从鸡场舍外下风方向分离到的多数大肠杆菌（54.5%）与从舍内空气或粪便中分离的大肠杆菌相似性可达100%。而从鸡舍上风向分离到的大肠杆菌与从舍内空气或粪便中分离的大肠杆菌相似性为73%-92%。从而说明来自动物体的大肠杆菌既能污染舍内空气,又能对其周围的环境构成污染。本研究揭示了微生物气溶胶的传播规律,具有公共卫生及流行病学意义。

In order to study the transmission of E. coli from chicken houses to their ambient air, the air samples, including indoor air, upwind air and downwind air of 5 chicken houses were collected using ANDERSEN-6 stages sampler and RCS. Chicken feces samples were collected according to the standard method. E. coli strains were isolated from these samples . The enterobacterial repetitive intergenic consensus （ERIC）-PCR method was applied to generate genomic amplification products of isolated E. coli. According to the concentration and genetic similarity of E. coli in every sampling site, the transmission of bioaerosol from animal houses to their ambient can be identified. The results showed that the culturable E. coli concentration in indoor air in 5 chicken houses were higher than that in upwind and downwind （P〈0.05 or P〈0.01）, but there were no significant differences in E. coli concentration among different downwind site （P〉 0.05）. The fingerprints and the phylogenetic tree indicated that a part of the E. coli （34. 1%） isolated from indoor air had the same ERIC-PCR fingerprints with those isolated from feces, the most of E. coli （54. 5%） isolated from downwind 10 m, 50 m, 100 m even 200 m away from the houses had the same ERIC-PCR fingerprints with those isolated from indoor air or feces. But E. coli isolated from upwind air had the low similarity coefficients （73 %-92 %） with those isolated from indoor air or feces. So, it was concluded that the E. coli in chicken feces can be aerosolized and transmitted into the indoor and outdoor air, especially the downwind air. This study revealed the transmitting rule of airborne E. coli bioaerosol. Hygienic measures took in animal farms have the significance of public hygiene and epidemiology.