我国南方猪高热病的研究(Ⅰ)——大肠杆菌的分离、鉴定和致病性测定

Research on Swine High Fever without Confirmed Pathogen(Ⅰ)——Isolation and Identification and Pathogenic Test about Escherichia coli

从湖南3个高热病发病猪场11头病死猪的病料组织中均分离出了大肠杆菌，经血清学鉴定，鞭毛抗原（K88、K99、987P和F41）全为阴性反应。经过157种菌体抗原血清学检测，血清型为5、6、15、22、32和83型。药物敏感试验结果表明，分离的大肠杆菌对大多数常用药物耐药，对氟喹诺酮和头孢类药物敏感。将其中4头猪原代分离的大肠菌培养物以原倍（2×10^7个／mL）、10^4和10^8稀释的菌液分别感染18—22g小白鼠，原倍菌液感染的小白鼠12／30在感染后24h内出现死亡，而10^4和10^8稀释菌液感染的小白鼠均健活；将未经除菌的病死猪组织悬液、过滤除菌的组织悬液、大肠杆菌、过滤除菌的组织悬液及大肠杆菌分别感染30日龄左右的健康小猪，除未经除菌的组织悬液感染猪3／3发病，2／3死亡外，其余所有感染猪只出现体温升高，升幅达1～2℃，减食，精神萎靡，但没有死亡；将死亡猪再次分离到的大肠杆菌感染小白鼠和猪，小白鼠12／15出现死亡，感染猪只出现体温升高（超过1℃），没有出现死亡。结果证明：大肠杆菌在高热病的发病过程中只起协同诱发作用，引起猪发病死亡的真正原因可能是病毒感染。

Escherichia coli （E. coli） were isolation from 11 infected and dead pigs in three pig-farms in Hunan province. Flagellum antigens（ K88, K99,987P and F41 ）wasn＇ t found in all of E. coli isolates by serological identification; 5, 6, 15, 22, 32 and 83 subtypes were identification by 157 bacteroides antigens serological test. And the result of drug sensitive test showed ： these pathogenic E. coli was resistant to 11 most daily used medicines, but fluoroquinolones and cephalosporin. Then 3 group mice （18 -22 g/each） were injected respectively with these E. coli by primary bacteria culture 2 × 10^7, 2 × 10^3 , 2 × 10^0 CFU/mL. 12/30 mice died after 24 h in the first group, and no mouse dead in other groups during 16 days. Tissues suspension liquid, tissues suspension liquid through filtrated from bacteria, E. coli isolates, tissues suspension liquid through filtrated from bacteria and E. coli isolates were injected respectively into test pigs（30 days old）, 2/3 pigs died in the first group, and no dead pigs was found in other groups, but body temperature rose （1-2℃） in all the pigs. Results indicated： these E. coli wasn＇ t primary pathogen in swine high fever without confirmed pathogen in Hunan province.