一株草鱼维氏气单胞菌的分离鉴定及毒力基因分析

doi:10.16431/j.cnki.1671-7236.2020.03.024

摘要/Abstract

摘要： 为了鉴定贵州芩巩县某养殖场草鱼发病死亡的病原，本研究通过临床解剖观察、细菌分离培养、革兰氏染色镜检、生化鉴定、药敏试验、动物回归试验、16S rDNA与gyr B基因测序及系统分析进行鉴定。结果显示，本研究从发病草鱼体内分离到1株致病菌GZQG2019，分离菌在培养基中呈圆形、表面湿润光滑、边缘整齐半透明的灰白色菌落，菌落周围呈现β-溶血环；革兰氏镜检显示，分离菌呈两端钝圆短小阴性杆菌；16S rDNA、gyr B基因序列分析显示，分离菌与维氏气单胞菌聚为一支，同源性均在99%以上；药敏试验结果显示，在使用的20种抗菌药物中，该菌对四环素、丁胺卡那、多黏菌素B和头孢曲松等10种药物敏感，对苯唑西林、青霉素、阿莫西林和庆大霉素等8种药物中度敏感，对头孢氨苄、复方新诺明2种药物耐药；动物回归试验显示，该菌对健康草鱼具有强致病性；10种毒力基因扩增结果显示，分离菌携带气溶素、热不稳定性肠毒素、溶血素、核酶、丝氨酸蛋白酶、弹性蛋白酶和酯酶7种毒力基因。本试验成功分离到1株草鱼源维氏气单胞菌，具有较强毒力，且携带多种毒力因子；对四环素、丁胺卡那等药物敏感，对四环素、丁胺卡那等耐药，为维氏气单胞菌病临床用药提供参考依据。

关键词: 草鱼; 维氏气单胞菌; 毒力因子

Abstract: In order to identify the pathogenic factors for the occurrence and death of grass carp of a farm in Qingong county,Guizhou province,this study identified the pathogens through clinical anatomical observation,bacterial isolation and culture,gram staining microscopic examination,biochemical identification,drug sensitivity test,animal regression test,16S rDNA and gyr B gene sequencing and systematic analysis.The results showed that a pathogenic bacteria strain GZQG2019 was isolated from the pathogenic grass carp.The isolated bacteria presented a round,moist and smooth surface with neat and translucent edges in the culture medium,and showed a beta hemolysis ring around the colony.Gram's microscopic examination showed that the isolated bacteria were obtuse short negative bacilli at both ends.The 16S rDNA and gyr B gene sequence analysis showed that the isolates and Aeromonas veronii converged into one branch,and the homology was more than 99%.The results of drug sensitivity test showed that among the 20 antibiotics,the bacteria was sensitive to 10 drugs,such as tetracycline,butylamicarine,polycolistin B and ceftriaxone,resistant to 2 drugs,such as cefalexin and compound xinomin,and moderately sensitive to 8 drugs,such as benzacillin,penicillin,amoxicillin and gentamicin.The results of animal regression showed that the bacteria was highly pathogenic to healthy grass carp.The amplification results of 10 virulence genes showed that the isolated bacteria carried 7 virulence genes including aerolysin,heat-unstable enterotoxin,hemolysin,ribozyme,serine protease,elastase and esterase.In this study,a strain of Aeromonas veronii from grass carp was successfully isolated with strong virulence and multiple virulence factors.The drug sensitivity test results provided a reference for clinical drug use of Aeromonas veronii with sensitivity to tetracycline and butanecanil and resistance to tetracycline and butanecanil.

Key words: grass carp; Aeromonas veronii; virulence factor

中图分类号:

R378.3

张飘, 胡安东, 杨霞, 潘吉脉, 姜海波, 文明. 一株草鱼维氏气单胞菌的分离鉴定及毒力基因分析[J]. 中国畜牧兽医, 2020, 47(3): 848-855.

ZHANG Piao, HU Andong, YANG Xia, PAN Jimai, JIANG Haibo, WEN Ming. Isolation Identification and Virulence Gene Analysis of a Grass Carp Aeromonas veronii[J]. China Animal Husbandry and Veterinary Medicine, 2020, 47(3): 848-855.

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