摘要
为查明引起四川省某养殖场大口黑鲈(Micropterus salmoides)死亡的病因,采用传统方法从患病大口黑鲈内脏组织中分离病原菌,通过人工回归感染试验确定其致病性,利用细菌生化微量鉴定管和16S rRNA序列分析鉴定病原菌,采用K-B纸片琼脂扩散法测定病原菌的药敏特性,并采取石蜡切片技术观察病鱼病灶组织的病理特征。结果显示,从病鱼体内分离得到1株优势菌(MYLY01),经生理生化和16S rRNA序列分析,确定其为维氏气单胞菌(Aeromonas veronii)。健康大口黑鲈感染病原菌后,出现与病鱼相似的临床症状和剖解变化,半数致死剂量(LD_(50))为4.79×10^(8) cfu/mL。药敏试验结果显示,病原菌对头孢拉啶、头孢他啶、庆大霉素和新霉素等敏感,对多西环素、四环素和阿莫西林等耐药。病鱼临床症状表现为体表溃疡,鳃丝充血、出血,肝脏、脾脏和肾脏肿大,组织病理学观察肝脏、脾脏、肾脏和肌肉组织均表现为明显的变性、坏死和炎性细胞浸润。以上结果表明,维氏气单胞菌是引起此次大口黑鲈疾病的致病菌,通过引起器官组织病理变化造成机体损伤而死亡,养殖过程中可选用新霉素等渔用药物进行防治。
This study was conducted to investigate the bacterial pathogen that caused the death of Micropterus salmoides farmed in Sichuan Province.Pathogenetic bacterial was isolated from naturally infected Micropterus salmoides by using traditional methods,and the pathogenicity was determined by artificial infection test.The pathogenic isolate was identified by biochemical identification micro reagent tube and 16S rRNA sequence analysis.Its antibiotic susceptibility was tested by Kirby-Bauer discagar diffusion method,and the histopathological characterization of organs of the diseased Micropterus salmoides was further observed by conventional paraffin section technique.The pathogenic strain MYLY01 was isolated from the diseased Micropterus salmoides and was identified as Aeromonas veronii based on phenotypic characteristics and 16S rRNA sequence analysis.It had an median lethal dose(LD_(50))of 4.79×10^(8) cfu/mL for healthy Micropterus salmoides,and showed the same clinical symptom as the diseased Micropterus salmoides.Drug sensitivity tested results showed that the MYLY01 was sensitive to cefradine,ceftazidime pentahydrate,gentamicin,neomycin and so on,but resistant to doxycycline,tetracycline,amoxicillin and so on.Clinical symptom of the diseased Micropterus salmoides showed ulcer in dorsum and side of the body,congestion and hemorrhage in gill,swelling in liver,spleen and kidney.Histopathological observation showed obvious degeneration,necrosis and inflammation in liver,spleen,kidney and muscles.The findings confirm that A.veronii is the cause of this epidemic which induces the body damages and even death because of the pathological changes in organs,and the neomycin will be used for the control of this disease in the future.
作者
邓龙君
DENG Longjun(Yalong River Hydropower Development Co.,Ltd.,Chengdu 610051,China)
出处
《河南农业科学》
北大核心
2021年第1期164-171,共8页
Journal of Henan Agricultural Sciences
基金
四川省农业产业技术体系建设项目(SCCXTD-15)。
关键词
大口黑鲈
维氏气单胞菌
分离鉴定
16S
rRNA
病理损伤
Micropterus salmoides
Aeromonas veronii
Isolation and identification
16S rRNA
Pathological lesions
