棘胸蛙脑膜炎败血伊丽莎白菌的分离鉴定及其感染的病理损伤

Isolation and identification of Elizabethkingia meningoseptica from Chinese spiny frog (Quasipaa spinosa) and pathological lesions of its infection

2016年4月四川雅安一棘胸蛙(Quasipaa spinosa)养殖场暴发一种临床特征表现为白内障、体表溃疡和神经症状的传染病。为明确此次流行病病因,本研究进行了病原菌分离、人工感染、分离菌理化特性与16S r DNA基因序列分析。结果从患病蛙肝、脾、肾中分离到一株G^-短杆菌(CM160701);将其腹腔注射感染健康棘胸蛙表现出与自然发病蛙相似症状。该菌的LD_(50)为1.19×10~6cfu·只^(-1);通过理化特性与16S r DNA基因序列分析鉴定分离菌为脑膜炎败血伊丽莎白菌(Elizabethkingia meningoseptica);其对氟苯尼考敏感,对恩诺沙星、多西环素、阿莫西林等多种药物耐受。病理组织学观察发现,其感染对全身多组织器官造成损伤,表现出明显的变性、坏死和炎症反应,尤以脑、肝、脾、心和肾损伤严重。该研究证实了脑膜炎败血伊丽莎白菌是本次疫情的病因,其感染引起棘胸蛙全身性损伤导致多组织器官功能障碍而死亡。

In April 2016,a serious infectious disease characterized by cataract,cutaneous ulcer and neurological symptoms emerged in a Quasipaa spinosa farm in Ya an,Sichuan Province.In order to explore the etiology,the pathogen isolation,artificial infection,physical and chemical characteristics of isolated bacteria and sequence analysis of 16S rDNA gene were analyzed.The results showed that a Gram-negative,short rod-shaped bacillus(CM160701)was isolated from the diseased frogs.Healthy Chinese spiny frogs injected the isolate intraperitoneally exhibited the similar clinical signs,gross and histopathological lesions to the naturally infected frogs,and the LD 50 value of the isolate was 1.19×10 6 cfu per frog.The isolated strain was identified to be Elizabethkingia meningoseptica according to physicochemical properties and the 16S rDNA gene sequence analysis.The strain was sensitive to florfenicol,but resistant to enrofloxacin,amoxicillin,doxycycline and so on.Histopathological observation found that the E.meningoseptica infection in Quasipaa spinosa could cause pathological damages to multiple organs which showed degeneration,necrosis and inflammation significantly,especially in the brain,liver,spleen,heart and kidney.This study confirmed E.meningoseptica was the pathogen of the epidemic,and the E.meningoseptica infection could cause Quasipaa spinosa multi-system injuries and lead to death.