鸭疫里默氏杆菌PT-RA1的分离鉴定、遗传进化分析及致病性试验

Isolation, identification, genetic evolution analysis, and pathogenicity test of Riemerella anatipestifer PT-RA1

摘要:

【背景】鸭疫里默氏杆菌(Riemerella anatipestifer,RA)是一种主要引起以鸭的纤维素性心包炎、肝周炎和气囊炎为临床特征的传染病病原，其血清型众多，防治困难。【目的】了解莆田市鸭疫里默氏杆菌的遗传特征、耐药情况和致病力情况，为该菌的治疗和防控提供科学依据。【方法】对来自莆田某养殖场疑似感染鸭传染性浆膜炎15日龄患病番鸭的脑组织进行分离纯化、16S rRNA基因鉴定和血清型鉴定，对该分离株的16S rRNA基因序列进行测序及遗传进化分析，并进一步测定其耐药性和对雏番鸭的致病性。【结果】分离得到一株11型鸭疫里默氏杆菌，将其命名为PT-RA1。PT-RA1分离株16S rRNA基因遗传进化上与鸭疫里默氏杆菌参考株广州株GZ-RA12、北京株CZ-RA03和山东株SD-RA2018处在同一进化分支上，相似性为100%，提示鸭疫里默氏杆菌可能存在跨地区传播；分离株对链霉素、庆大霉素和卡那霉素等15种抗生素表现多重耐药，而对氨苄西林、阿莫西林、头孢唑林、头孢曲松、四环素、强力霉素、头孢克肟、头孢吡肟、氧氟沙星、氟苯尼考敏感；对该分离株进行雏番鸭致病性试验，死亡率80%，病死鸭出现纤维素性心包炎、肝周炎、气囊炎和脾脏肿大等典型的鸭疫里默氏杆菌病临床特征症状。【结论】分离并鉴定一株11型鸭疫里默氏杆菌PT-RA1，为鸭疫里默氏杆菌病的防控及后续研究提供参考依据。

关键词:鸭疫里默氏杆菌;分离鉴定;遗传进化;致病性

Abstract:

[Background] Riemerella anatipestifer is a pathogen causing fibrinous pericarditis, perihepatitis, and airsacculitis in ducks. With a variety of serotypes, this pathogen is difficult to be prevented and controlled. [Objective] To understand the genetic characteristics, drug resistance and pathogenicity of Riemerella anatipestifer in Putian city, and provide scientific basis for its treatment and prevention. [Methods] Isolation and purification, 16S rRNA gene identification, and serotype identification were performed on the brain tissue of 15-day-old ducklings suspected to be infected with orrhomeningitis from a breeding farm in Putian. The 16S rRNA gene of this isolate was sequenced, based on which the genetic evolution analysis was performed. Furthermore, the antibiotic resistance of the strain and the pathogenicity to ducklings were determined. [Results] A strain of Riemerella anatipestifer serotype 11 was isolated, named PT-RA1. The 16S rRNA gene of PT-RA1 was in the same branch on the genetic evolution tree as those of the reference strains (GZ-RA12, CZ-RA03, and SD-RA2018) of R. anatipestifer, with 100% similarity, which suggested that R. anatipestifer may have spread across different regions. The isolate was resistant to 15 antibiotics including streptomycin, gentamicin, and kanamycin, while it was sensitive to ampicillin, amoxicillin, cefazolin, ceftriaxone, cefixime, cefepime, tetracycline, doxycycline, oxfloxacin, and florfenicol. The isolate caused a mortality rate of 80% in ducklings, and the dead ducks showed typical symptoms such as fibrinous pericarditis, perihepatitis, airsacculitis, and spleen enlargement of R. anatipestifer infection. [Conclusion] We isolated and characterized a R. anatipestifer strain PT-RA1, which provided a basis for the prevention and control of R. anatipestifer infection and subsequent research.

Key words:Riemerella anatipestifer;isolation and identification;genetic evolution;pathogenicity