【摘要】 为探明斑点叉尾■（Ictalunes punctatus）溃烂症的病因,从4尾患鱼肝脾中分离纯化出4株优势菌株,并进行病原鉴定、毒力基因检测、动物回归感染和药敏试验。4株优势菌经鉴定并命名为杀鲑气单胞菌无色亚种（Aeromonas salmonicida subsp achromogenes）X-G1,杀鲑气单胞菌杀鲑亚种（A.s subsp salmonicida）X-P2、X-P3和嗜水气单胞菌（A.hydrophila）X-P4。15℃时,杀鲑气单胞菌X-G1、X-P2和X-P3的世代时间（约14 min）均小于嗜水气单胞菌X-P4（约20 min）;25℃时,杀鲑气单胞菌X-G1、X-P2和X-P3株的世代时间（约20 min）均大于嗜水气单胞菌X-P4株（约16 min）。X-G1株可检到弹性蛋白酶、溶血素和甘油磷脂胆固醇酰基转移酶等3种毒力基因;X-P2株仅可检到弹性蛋白酶1种毒力基因;X-P3株可检测到弹性蛋白酶、溶血素、细胞毒性肠毒素、丝氨酸蛋白酶、酯酶、气溶素和甘油磷脂胆固醇酰基转移酶等7种毒力基因;X-P4株可检测到鞭毛、弹性蛋白酶、气溶素、细胞毒性肠毒素、热不稳定性肠毒素、丝氨酸蛋白酶和溶血素等7种毒力基因。分离株X-G1、X-P2、X-P3和X-P4在15～17℃水温下腹腔注射攻毒的半数致死浓度(LD₅₀)依次为0.49×10⁴、0.78×10⁴、0.53×10⁴、3.84×10⁴CFU/g;而在23～26℃水温下测得的LD₅₀依次为1.48×10⁴、1.80×10⁴、0.82×10⁴、0.68×10⁴CFU/g。分离株混合感染比单一株感染均表现出更强的致死能力。分离菌株对多西环素、恩诺沙星、氟苯尼考均敏感,但因患病鱼不能摄食药饵而导致治疗失败。更多还原

【Abstract】 Four dominant strains were isolated and purified from four fish liver or spleen of Ictalunes punctatus to determine the cause of the ulcer disease.Meanwhile,pathogen identification,virulence gene test,animal regression challenge and drug sensitivity test were carried out.Four dominant bacteria were identified and named as Aeromonas salmonicida subsp achromogenes X-G1 strain,A.salmonicida subsp salmonicida X-P2 strain,X-P3 strain and A.hydrophila X-P4 strain.The generation time（about 14 min） of A.salmonicida was less than that of A.hydrophila（about 20 min） at 15 ℃.While the generation time（about 20 min） of A.salmonicida was more than that of A.hydrophila（about 16 min） at 25 ℃.X-G1 strain could detect three virulence genes of ahyB,hlyA and GCAT.X-P2 strain could only detect one virulence gene of ahyB.X-P3 strain could detect seven virulence genes,including ahyB,hlyA,Act,Ser,aerA,Lip and GCAT.X-P4 strain could detect seven virulence genes,including Fla,ahyB,aerA,Act,Alt,Ser and hlyA.The LD₅₀ of X-G1,X-P2,X-P3 and X-P4 strains were 0.49×10⁴,0.78 ×10⁴,0.53×10⁴ and 3.84×10⁴ CFU/g under water temperature of 15～17 ℃,respectively.While the LD₅₀ of the four strains were 1.48 ×10⁴,1.80×10⁴,0.82 ×10⁴ and 0.68×10⁴ CFU/g under water temperature of 23～26 ℃,respectively.Mixed infection of isolate strains showed stronger lethality than single infection.The isolated strains were sensitive to doxycycline,enrofloxacin and florfenicol,but the treatment failed because the sick fish could not take medicine.更多还原