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| 香鱼(Plecoglossus altivelis)致病性类志贺邻单胞菌的分离与生化药敏鉴定 |
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阚宏玉1,2, 苗亮1,2, 杜杨1,2, 李明云1,2, 巩晓琳1,2, 李文雅1,2, 孙振南1,2, 石海瑞1,2, 张立宁3
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1.宁波大学 农产品质量安全危害因子与风险防控国家重点实验室 浙江宁波 315211;2.宁波大学 水产生物技术教育部重点实验室 浙江宁波 315832;3.浙江省海洋水产养殖研究所 浙江温州 325005
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| 摘要: |
| 香鱼(Plecoglossus altivelis)是名贵洄游性鱼类,由于高密度养殖等因素导致病害频发。2021年7月强台风"烟花"过境后浙江省宁海县养殖香鱼暴发体表溃烂病,死亡严重。病鱼皮肤、肌肉溃烂并伴有周围皮肤充血。组织切片观察显示病鱼患处肌纤维断裂,周围红细胞、炎性细胞浸润;鳃丝和鳃小片中红细胞增多;肝细胞核呈空泡,部分细胞核染色质边集;脾脏内红细胞数量减少,部分白细胞聚集;肠黏膜上皮细胞脱落。从患病香鱼肠中分离到一株菌(编号NH21),其菌落低突、边缘光滑表面湿润,该菌株为革兰氏阴性菌,菌体呈短杆状、端圆。经生化特性和16S rDNA序列分析鉴定NH21菌株为类志贺邻单胞菌(Plesiomonas shigelloides)。用该菌株对健康香鱼进行回归感染后,人工感染香鱼呈现与本次体表溃烂病香鱼相似的症状,经计算NH21菌株对香鱼的半致死剂量(LD50)为2.51×107 CFU/mL。25种抗生素的药敏试验显示NH21菌株对阿奇霉素、头孢氨苄、新生霉素、多黏菌素B、头孢西丁、呋喃唑酮6种抗生素敏感。从NH21菌株中检出了毒力基因9个、耐药基因8个。综合分析表明,分离得到的类志贺邻单胞菌NH21菌株是本次宁海县香鱼体表溃烂病的病原菌,研究结果为香鱼出现类似病症的预防和治疗提供了基础资料。 |
| 关键词: 香鱼(Plecoglossus altivelis) 类志贺邻单胞菌 回归感染 半致死剂量(LD50) 药物敏感性 |
| DOI：10.11693/hyhz20220300074 |
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| 基金项目:浙江省基础公益研究计划项目“香鱼全雌苗种规模化繁育技术研究”,LGN20C190009号。 |
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| ISOLATION, BIOCHEMICAL IDENTIFICATION, AND ANTIBIOTIC SENSITIVITY OF PATHOGENETIC PLESIOMONAS SHIGELLOIDES ISOLATED FROM SWEETFISH PLECOGLOSSUS ALTIVELIS |
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KAN Hong-Yu1,2, MIAO Liang1,2, DU Yang1,2, LI Ming-Yun1,2, GONG Xiao-Lin1,2, LI Wen-Ya1,2, SUN Zhen-Nan1,2, SHI Hai-Rui1,2, ZHANG Li-Ning3
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1.State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agroproducts, Ningbo University, Ningbo 315211, China;2.Key Laboratory of Aquacultral Biotechnology, Ministry of Education, Ningbo University, Ningbo 315832, China;3.Zhejiang Mariculture Research Institute, Wenzhou 325005, China
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| Abstract: |
| Sweetfish (Plecoglossus altivelis) is a rare migratory fish, and often suffer diseases in high-density farming. Plesiomonas shigelloides is widely present in aquaculture water environment, and there are some cases of significant economic losses caused by infection of P. shigelloides in aquaculture. In July 2021, after the severe typhoon "In-Fa" passed by, a festering disease broke out and caused heavy mortality in farmed P. altivelis in Ninghai County, Zhejiang Province. The skin and muscles of the diseased fish are ulcerated and accompanied by hyperemia of the surrounding skin. Observation of tissue sections showed that the muscle fibers in the affected area of the diseased fish were broken, and the surrounding erythrocytes and inflammatory cells were infiltrated. The erythrocytes in the gill filaments and gill lamellae increased, the nuclei of liver cells were vacuolated, and some nuclei were chromatin bordered. The number of erythrocytes in the spleen decreased, and some leukocytes were aggregated and intestinal mucosal epithelial cells slough off. A bacterial strain (named NH21) was isolated from intestine of diseased fish. Observation by light microscope with gram staining showed that the isolated strain NH21 was Gram-negative with blunt round ends. The colony characteristics of NH21 were low and flat, the edge was smooth, and the surface was moist. The NH21 strain was identified as P. shigelloides by biochemical characterization and 16S rDNA sequence analysis. After the artificial infection of healthy P. altivelis with NH21 strain, the artificially infected fish showed similar symptoms to the naturally infected fish. The calculated LD50 of the NH21 strain to P. altivelis is 2.51×107 CFU/mL. The susceptibility test of 25 antibiotics showed that the NH21 strain was sensitive to azithromycin, cephalexin, novobiocin, polymyxin B, cefoxitin, and furazolidone. Nine virulence genes and eight drug resistance genes were detected in NH21 strain. The comprehensive analysis showed that the P. shigelloides NH21 strainwas the pathogen of the festering disease on the body surface of P. altivelis in Ninghai County. The research results provided basic data for the prevention and treatment of similar diseases in P. altivelis. |
| Key words: sweetfish (Plecoglossus altivelis Plesiomonas shigelloides artificial infection lethal does 50% (LD50) antibiotic susceptibility |
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