异育银鲫气单胞菌病原菌鉴定和药敏试验

从患病异育银鲫体内分离到5株可疑菌株,经API 20NE细菌生化鉴定,YCS07-03和YZ07-11株鉴定率为99.2%和99.3%。注射感染中5×108 CFU.mL-1剂量组表现出较强的致病性,12 d死亡率100%。菌株在营养肉汤培养液中呈均匀混浊状;在营养琼脂平皿中呈灰白色半透明菌落;在血琼脂培养基中呈光滑灰白色菌落,YZ07-11株出现透明的β溶血环;在TCBS培养基呈黄色菌落;在SS和麦康凯培养基中形成无色透明的扁平菌落。经负染电镜观察,菌株两端圆,呈直杆状,无芽孢,极生单鞭毛,菌株大小(短径×长径)分别为1.53μm×2.71μm和0.80μm×2.12μm。菌株经生化实验鉴定为温和气单胞菌(Aeromonas sobria)和嗜水气单胞菌(Aeromonas hydrophila)。试验结果表明:菌株对丁胺卡那霉素、头孢噻肟、庆大霉素、左氟沙星、复合磺胺、氟嗪酸、洛美沙星、复方新诺明、链霉素和新霉素均产生高度敏感;对万古霉素为中度敏感;氨苄青霉素、羧苄青霉素、强力霉素和青霉素产生耐药。

Identification and Drug Sensitive Test of the Pathogen of Aeromonas Disease from Hybridized Prussian Carp (Carassius auratus gibelio♀ ×Cyprinus carpio♂)

5 bacteria were isolated from the visceral samples of dying Hybridized Prussian carp(Carassius auratus gibelio♀×Cyprinus carpio♂).The identification percentage of strains YCS07-03 and YZ07-11 were 99.2% and 99.3% by API 20NE,respectively.The injection dosage of 5×108 CFU.mL-1 showed intense pathogenicity and caused 100% mortality in 12 days.Strains became uniform turbidness in Nutrient Broth and showed gray white translucent colonies in Nutrient Agar.Isolated strains were smooth,gray white and β-hemolytic on rabbit blood agar.In addition,strains grew well in TCBS,SS and MacConkey agars,which performed yellow and colorless transparent colonies,respectively.Negative staining electron micrograph revealed that the strains were straight rods with rounded ends,motile by a single,polar flagellum and did not come into being gemma.Stain YCS07-03 and YZ07-11 are 1.53 μm × 2.71 μm and 0.80 μm ×2.12 μm in diameter.The result of biochemical identification showed that strain YCS07-03 was Aeromonas sobria and strain YZ07-11 was Aeromonas hydrophila.The drug sensitive test demonstrated that the stains had high sensitivity to amikacin,cefotaxime,gentamicin,etc,but had theresistance to ampicillin,carbenicillin,doxycycline and Penicillin.