罗氏沼虾费氏柠檬酸杆菌的分离鉴定及药敏分析

Isolation and identification of Citrobacter freundii from diseased Giant freshwater prawn(Macrobrachium rosenbergii)

从患了典型黑鳃病的罗氏沼虾(Macrobrachium rosenbergii)的病灶处进行细菌接种,分离获得1株菌株CF9527。综合菌落形态、16 S r RNA序列进化分析和细菌生理生化系统鉴定,所得菌株为费氏柠檬酸杆菌(Citrobacter freudii)。人工感染试验显示,该菌株对罗氏沼虾的半数致死量(LD50)为1.68×106CFU/m L,说明该菌株具有较强的致病性而且可从试验罗氏沼虾体内再次分离到相同的病原菌。常用药物的抗菌敏感性测定试验显示,菌株CF9527对万古霉素、单环霉素、复方新诺明、氧氟沙星、恩诺沙星、阿莫西林、氨苄西林、头孢吡肟、头孢曲松、先锋霉素Ⅴ、新霉素高度敏感。本研究进一步确定了病原菌的致病性、耐药性和分类地位,为养殖罗氏沼虾黑鳃病的防控提供参考。

Bacteria were isolated from the nidus of Giant freshwater prawn（Macrobrachium rosenbergii） and through the colony morphology,Gram＇s staining,bacterial biochemical identification system and sequence analysis of 16 S r RNA gene,the isolate bacteria was identified as Citrobacter freundii,named CF9527.The healthy Giant freshwat er prawn（Macrobrachium rosenbergii） were used for experiment al infect ion wit h bact erial suspension,and the same bacteria could be recovered.Isolate CF9527 was demonstrated to have a virulent potential in Giant freshwat er prawn,wit h a median let hal dose（LD50） of 1.68×10^6 CFU/m L.The suscept ibilit y t est t o ant ibiot ics demonstrated that the bacterial strain CF9527 was highly susceptible to vancomycin,monocyclic drug,sulfa-methoxazole,ofloxacin,enrofloxacin,ciprofloxacin,amoxicillin,ampicillin,cefepime,ceftriaxone,cephalexin Ⅴ and neomycin.