鸭源金黄色葡萄球菌的分离鉴定及致病性研究

发布时间：2018-03-03 08:05

本文选题：鸭　切入点：金黄色葡萄球菌　出处：《山东农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：鸭葡萄球菌病主要是由金黄色葡萄球菌引起的鸭的一种急性或慢性传染病。本病主要侵害育成鸭和种鸭,以关节肿胀,关节腔内有脓性或浆液性纤维渗出,肝脏肿大,脾脏肿大、坏死为主要特征。近年来,鸭葡萄球菌病多发,对养鸭业造成巨大危害,加强对金黄色葡萄球菌的研究,对防治该病具有重要意义。本研究从临床送检的病料中分离细菌,并对其进行了培养特性、形态学特征、生理生化特性和分子生物学特性分析,鉴定为金黄色葡萄球菌。药敏试验结果显示,分离株呈现不同程度耐药,且多重耐药现象比较严重。多数分离菌株对头孢拉定、头孢噻肟、米诺环素高度敏感。根据GenBank公布的金黄色葡萄球菌肠毒素基因和耐药基因序列,设计并合成了7种肠毒素基因引物以及4种耐药基因引物。PCR检测结果表明,56株金黄色葡萄球菌中肠毒素G型、B型的检出率最高,分别为32.1%、26.8%;其次是肠毒素A型、C型和H型,检出率分别为17.9%、16.1%、16.1%;肠毒素D型和E型的检出率低,依次为12.5%、8.9%。可见不同菌株之间肠毒素基因分布存在差异性。分离鉴定的56株金黄色葡萄球菌中,含有mecA耐药基因的占60.7%(34/56);含有femA耐药基因的占37.5%(21/56);含有grlA耐药基因的占48.2%(27/56);含有norA耐药基因的占55.4%(31/56)。而且同一株菌能检测出2种或2种以上耐药基因。皮下接种金黄色葡萄球菌人工感染育成鸭,观察鸭的临床表现。接种后在不同时间内随机剖杀试验组和对照组的鸭子,观察各脏器的病理变化,并对部分组织器官进行细菌的分离鉴定。同时,采集肝脏、脾脏、肾脏、肺脏、心脏等组织进行甲醛固定、切片观察各组织器官的病理组织学变化。结果显示:试验组鸭胸腹部皮下充血、出血、有胶冻样水肿液,肝脏肿大,脾脏肿大,肺脏出血、水肿,肾脏肿大,公鸭睾丸肿大、出血。对照组鸭剖检未见明显病变。试验鸭中分离的细菌与接种菌形态特征完全一致,且不同组织器官的分离率各不相同,其中关节分离率最高。病理组织学变化以肝脏脂肪变性、肝细胞坏死,脾脏淋巴细胞大量减少、脾脏坏死,肾脏空泡变性、肾小管上皮细胞坏死等为主要特征。
[Abstract]:Staphylococcosis is an acute or chronic infectious disease in ducks caused mainly by Staphylococcus aureus. It mainly affects adult ducks and breeding ducks, with swelling of the joints, exudation of purulent or serous fibers in the articular lumen, and enlargement of the liver. Splenomegaly and necrosis are the main characteristics. In recent years, staphylococcal disease in ducks is more frequent, which causes great harm to duck industry, and strengthens the research on Staphylococcus aureus. In this study, bacteria were isolated from clinical samples, and the characteristics of culture, morphology, physiology and biochemistry, and molecular biological characteristics were analyzed. Staphylococcus aureus was identified as Staphylococcus aureus. The results of drug sensitivity test showed that the isolates showed different degrees of drug resistance, and the phenomenon of multidrug resistance was serious. Most of the isolates were resistant to cefradine and cefotaxime. Minocycline is highly sensitive. According to the sequence of enterotoxin gene and drug resistance gene of Staphylococcus aureus published by GenBank, Seven enterotoxin gene primers and four drug-resistant gene primers were designed and synthesized. The results showed that the detection rate of Enterotoxin G type B was the highest in 56 strains of Staphylococcus aureus, which was 32.1% and 26.8% respectively, followed by enterotoxin A type C and H type. The detectable rates of enterotoxin D and E were lower, which were 12.5% and 8.9%, respectively. The distribution of enterotoxin gene was different among different strains. Among the 56 strains of Staphylococcus aureus isolated and identified, there were significant differences in the distribution of enterotoxin gene among them. 60.7% had mecA resistance gene, 37.5% had femA resistance gene, 48.2% had grlA resistance gene, 55.44% had norA resistance gene, and the same strain could detect two or more resistant genes. Subcutaneously inoculated staphylococcus aureus subcutaneously. Grape coccus artificially infects adult ducks, The clinical manifestations of ducks were observed. After inoculation, the ducks of the test group and the control group were killed at random, the pathological changes of each organ were observed, and some tissues and organs were isolated and identified. At the same time, liver, spleen and kidney were collected. Lung, heart and other tissues were fixed with formaldehyde. The histopathological changes of tissues and organs were observed by sections. The results showed that the experimental group had hypodermic hyperemia, hemorrhage, gelatinous edema, hepatomegaly, splenomegaly and pulmonary hemorrhage. Edema, enlargement of kidney, enlargement of testis and hemorrhage in male duck. No obvious pathological changes were found in the control group. The morphological characteristics of bacteria isolated from the tested duck were completely consistent with those of inoculation bacteria, and the isolation rates of different tissues and organs were different. The histopathological changes were mainly characterized by fatty degeneration of liver, necrosis of hepatocytes, reduction of splenic lymphocytes, necrosis of spleen, degeneration of kidney vacuoles and necrosis of renal tubular epithelial cells.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S858.32

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