1株鸡源鸭疫里默氏杆菌的分离鉴定及其生物学特性分析OA北大核心CSTPCD

In order to understand the pathogenicity of Riemerella anatipestifer of chicken origin,a suspected strain isolated in 2021 from a diseased chicken liver was examined by staining microscopy,biochemical reactions,serotyping,drug susceptibility test,animal pathogenicity and 16S rRNA sequencing.This strain did not ferment sugars and produced positive results in urease,catalase,oxidase reduction,citrate utilization and gelatin liquefaction testings but negative reactions for sulfide,VP and MR testings.Serotyping demonstrated it was serotype 10.This strain was highly susceptible to ampicillin,amoxicillin,ceftiofur,ciprofloxacin,sulfamethoxazole,erythromycin,doxycycline and florfenicol and resistant to ceftriaxone,enrofloxacin,spectinomycin and gentamicin.Animal tests showed that it caused"three inflammatory"signs in ducks and chickens with high mortality in ducks and severe joint and soft tissue lesions in chickens.Pathological examinations showed that the infected chicken had thick epicardium with full fibrins,inflammatory cell infiltration with mainly lymphocytes.Other pathological changes included focal inflammatory cell infiltration in livers with mainly lymphocytes,deep stained pyknosis of cytoplasm and nucleus in some hepatocytes,a small amount of lymphocyte infiltration around the blood vessels of spleens,exudate in leg tissues and a large number of inflammatory cells around the blood vessels.Alignment of 16S rRNA sequences showed that the homology between this strain and other GenBank reference strains was more than 99％,confirming it was R.anatipestifer.Genetic evolution analysis showed that this strain was highly homologous to the most virulent R.anatipestifer Hxb2 strain isolated from Shanghai Veterinary Research Institute.This experiment proved that the chicken-derived R.anatipestifer QD01 strain had strong pathogenicity to chickens and ducks.