【作者】 杨春浩；

【导师】 肖克宇；

【作者基本信息】 湖南农业大学 ， 水产养殖， 2010， 硕士

【摘要】 近年来,湖南岳阳市云溪区某养殖户牛蛙腹部肿大,体色发黑,头斜向一面,在水中做“旋转”式游动,解剖后可见腹部有大量脓血水流出,肝脏大呈深紫色,肾脏充血呈鲜红色等症状。由此自然症状可诊断为牛蛙歪头病。分别对牛蛙歪头病病蛙的腹腔、肝脏、肠、肾、胃等组织分离病原菌,经分离、纯化、鉴定,获得两种病原菌,分别为藤黄葡萄球菌(Micrococcus luteus)、浅黄假单胞菌(Pseudomonas mendocina),这是牛蛙病原菌的两种新病原。最佳致病浓度筛选试验结果表明：当两种病原菌按1：1配比,浓度达到1.1×109时,其致病性最强；最佳部位感染筛选试验结果表明：从眼部注射发病快,其发病症状与自然发病症状完全一致。因此认为藤黄葡萄球菌和浅黄假单胞菌是牛蛙歪头病的病原菌,且通过眼睛感染症状明显。病原毒力因素构成试验结果表明：藤黄葡萄球菌和浅黄假单胞菌两种病原菌在血琼脂培养基(37℃)培养24h,出现溶血环,均为阳性；解剖健康蛙,将两种病原菌分别按一定剂量注射蛙肠,养殖48h,观察表明外毒素为阳性；两种病原菌与鲎试剂发生反应,形成牢固凝胶,倒持凝胶不动,均表明内毒素为阳性。两种病原菌均产生内、外毒素,并能引起细胞溶血和坏死。取自然发病蛙和人工感染病蛙进行组织病理学检查,观察到局部皮肤出现炎症,充血,坏死溶解,急性化脓性肌炎,以及肺炎,轻度卡他性胃肠炎,肝坏死,化脓性肾炎,急性脾炎。药敏实验表明：在20种药物中,两种病原菌只对头孢哌酮、妥布霉素、头孢曲松等5种药敏感；而对氟哌酸、环丙沙星、头孢噻肟等13种药物不敏感。所以各种抗菌药物在防治上没有明显效果。另外,由于该病原菌位于大脑和眼球等关键部位,因大脑屏障的保护作用,一般的药物难以深人其中。因此,该病一旦发生,死亡率将达到95%以上,甚至达到100%。上述结果表明,牛蛙歪头病机理是特定细菌经眼部感染而引起的传染性疾病,病死蛙表现为脑部的病症与其产生外毒素及感染部位有关。更多还原

【Abstract】 In recent years, it can be diagnosed as Bullfrog Wry Head Disease. Taking the symptoms into consideration that intumescent abdomen, darkening body, wrying head to one side, swim in rotating way, large amount of bloody pus dissection in its abdomen, tumid and dark purple liver, hyperaemia of kidney with fresh red color etc, appeard in Bullforg farms in Yunxi District of Yueyang City Hunan Province.Respectively abdomen, liver, intestine, kidney, stomach and other organizations of Bullforg extract the bacteria, separation, purification, identification, were carried out, and the result confirmed that Micrococcus luteus and Pseudomonas mendocina, this is the bullfrog Two New pathogen. The result of the best concentration screening test showed that:When the two kinds of pathogens according to 1:1, concentration of 1.1×109, its most pathogenic; The result of the best infection screening test showed that:form the eye injection so that incidence fast, and the same symptoms of incidence and nature. Therefore considered that Micrococcus luteus and Pseudomonas mendocina though the eye infection is obviously, and is pathogens of Bullfrog Wry Head Disease.The result of virulent factors constitute tests showed that:Micrococcus luteus and Pseudomonas mendocina in the Blood agar(37℃) cultured 24h, were no hemolysis ring, were negative; They and LAL reaction to form a solid gel, hold down fixed gel showed that endotoxin-positive; Injected at certain dose of healthy frog intestine, breeding 48h, observations show that exotoxin positive.Histopathological examinations of naturally occurring and experimentally infected cases were carried out. Important finds were inflammation, hyperemia, necrosis, and gangrene of local skin, as well as acute suppurative myositis, pneumonia, mild catarrhal gastroenteritis, hepatic necrosis, suppurative nephritis, acute aplenitis.Antibiotic sensitivity experiments showed that:The bacteria is highly sensitive to the 5 antibiotics, including a Cefoperazone, Levofloxacin and Fosfomycin, but not to the 13 antibiotics such as Chloramphenicol, Ciprofloxacin and Gentamicin in the 20 antibiotics. Therefore, there is no obvious affection a variety of antimicrobial drugs in the prevention and treatment. In addition, It is general difficult depth in, because the pathogen in the key parts of the brain and the eye and the brain barrier function. When the disease occurs, mortality rate will reach 95%, even up to 100%.The results mentioned above shown that the Wry Head Disease of Bullfrog was specific bacterial eye infections caused by infectious diseases, Related performance of the brain of Dead frog’s disease to its exotoxin produced and the site of infection.更多还原