罗非鱼(Tilapia nilotica)简达气单胞菌病的病原分离鉴定及药敏试验

Isolation, Identification and Drug Sensitive Test of Aeromonas jandaei from Tilapia (Tilapia nilotica)

中文关键词: 罗非鱼  简达气单胞菌  致病性  分离鉴定  药敏试验

英文关键词: Tilapia nilotica  Aeromonas jandaei  Pathogenicity  Isolation and identification  Sensitivity test

中文摘要:

      从患病罗非鱼(Tilapia nilotica)体内分离得到细菌NL05，通过回归感染试验确定NL05为致病菌，并测出NL05对罗非鱼的半致死量(LD50)为1×103 CFU/g。结合细菌形态学特征、生理生化指标和16S rRNA基因同源分析，鉴定NL05为简达气单胞菌(Aeromonas jandaei)。形态学观察发现，NL05为革兰氏阴性、短杆状；生理生化试验中麦芽糖、甘露醇、葡萄糖、水杨素、硫化氢等13种指标为阳性，蔗糖、阿拉伯糖、木糖、肌醇、卫矛醇等10种指标为阴性。药敏试验显示，NL05对奥复星、丙氟哌酸、丁胺卡那霉素、多粘菌素B、氟哌酸、利福平、洁霉素等13种抗生素敏感，对阿奇霉素、菌必治、卡那霉素、链霉素、美满霉素5种抗生素中介，对氨苄青霉素、阿莫西林、恩诺沙星、复方新诺明、甲氧苄啶等13种抗生素耐药

英文摘要:

      Tilapia is a very important freshwater aquacultural species in China; however, bacterial disease caused huge economic losses in recent years with the continous expansion of tilapia aquaculture. The aim of this research was to isolate, identify, and test drug sensitivity of bacteria pathogen found in diseased Tilapia nilotica. Six bacteria were isolated from diseased T. nilotica as suspected pathogenic bacteria. The bacteria (NL05) isolated from intestine of diseased T. nilotica was determined as pathogenic bacteria by infection experiment. The LD50 was 1×103 CFU/g. Bacteria NL05 was identified as Aeromonas jandaei. Morphology observation indicated that NL05 was gram-negative, rod-shaped. Thirteen physiological and biochemical indexes were positive including maltose, mannitol, glucose, salicin, and hydrogen sulfide. Ten indexes were negative including saccharum, arabinose, xylose, inositol, and dulcitol. There was 1442 bp in the sequence of 16S rRNA, which was submitted into GenBank (Accession number: KC916744). The phylogenetic tree based on 16S rRNA showed that NL05 was A. jandaei. Drug sensitivity test indicated that NL05 was sensitive to 13 antibiotics including ofloxacin, ciprofloxacin, amikacin, polymyxin B, norfloxacin, rifampicin, and lincomycin, and intermediate sensitive to 5 antibiotics including azithromycin, ceftriaxone, kanamycin, streptomycin and minocycline, and resistant to 13 antibiotics including ampicillin, amoxicillin, enrofloxacin, sulfamethoxazole, and trimethoprim. The results will provide references for the prevention and treatment of diseases caused by T. nilotica.