中文摘要：

从疑似副猪嗜血杆菌和猪丹毒丝菌混合感染病猪无菌采集心脏、肝脏、脾脏、肺及心包积液,采用常规分离培养法分离病原菌,通过染色镜检、生化鉴定、卫星试验和核酸测序同源性比对,确诊为副猪嗜血杆菌与猪丹毒丝菌混合感染。为进一步了解2株菌的生物学特性,测定了2株菌以及混合菌液的半数致死量（LD50）以及对常用抗生素的药物敏感性。结果显示：（1）将2株菌的序列与GenBank数据库中已发表序列进行同源性比对,副猪嗜血杆菌与猪丹毒丝菌的同源性各达到96%和99%;（2）致病性试验中,SPF鼠均在接种后24h左右开始死亡,从其心脏、肝脏、脾脏及肺均回收到攻毒菌,表明2株菌均为此次疫病的主要致病菌;（3）通过测定副猪嗜血杆菌和猪丹毒丝菌的LD50分别为5.28×10^9、3.58×10^4 CFU/mL,进一步证明二者具有较强毒性。根据2株菌的LD50等体积混合2种菌液注射SPF鼠,副猪嗜血杆菌与猪丹毒丝菌LD50均出现下调,分别为3.70×10^9、2.51×10^4 CFU/mL,表明混合感染增强了二者的致病力;（4）药敏试验结果显示副猪嗜血杆菌与猪丹毒丝菌对常用抗生素的耐药性与临床耐药谱相一致,未出现新的耐受药物;同时筛选出了2种菌的共敏感药物氧氟沙星和氟苯尼考,有利于对疾病的快速治疗与防控。

英文摘要：

Aseptically collected heart,liver,spleen,lungs and andpericardial effusion from sick swine suspected mixed infecting Haemophilus parasuis and Erysipelothrix rhusiopathiae.Took conventional isolation and culture to isolate pathogens,and diagnosed as mixed infected Haemophilus parasuis and Erysipelothrix rhusiopathiae by staining,biochemical identification,cmptesting and nucleic acid homology alignment.To further understand the biological characteristics of the two strains,determined median lethal dose（LD50）of the two strains and their mixed bacteria,and drug susceptibility to commonly used antibiotics.The results showed：（1）Sequence homology of Haemophilus parasuis and Erysipelothrix rhusiopathiae with the published in the GenBank database were 96% and 99%,respectively.（2）In pathogenicity tests,SPF mice died at about 24 hafter inoculation,and the attack germs were recycled from the heart,liver,spleen and lung,suggesting that the two strains are major pathogens of this disease.（3）The median lethal dose of Haemophilus parasuis and Erysipelothrix rhusiopathiae was 5.28×109 CFU/mL and 3.58×104 CFU/mL,indicating that the two strains have strong toxicity.According to the median lethal dose of the two strains,mixed two bacteria with an equal volume injected SPF mice.Both of the median lethal dose of Haemophilus parasuis and Erysipelothrix rhusiopathiae came down,and were 5.28 ×10^9 CFU/mL and 3.58×10^4 CFU/mL,showing mixed infections enhanced their virulence.（4）Drug sensitivity test showed the drug resistance of Haemophilus parasuis and Erysipelothrix rhusiopathiae to commonly used antibiotics were consistent with clinical resistance spectrum,without new tolerated antibiotic,while filtering out the co-sensitive drugs,ofloxacin and florfenicol.