| 罗伟杰,史磊,黄瑜,等.大口黑鲈源豚鼠气单胞菌的分离、鉴定及病理性分析[J].广东农业科学,2024,(6):- |
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大口黑鲈源豚鼠气单胞菌的分离、鉴定及病理性分析 |
| Isolation, Identification and Pathogenicity Analysis of Aeromonas caviae from Micropterus Salmoides |
| 投稿时间：2024-05-10 修订日期：2024-08-05 |
| DOI： |
| 中文关键词: 大口黑鲈 豚鼠气单胞菌 16S rDNA 药敏试验 毒力基因 组织病理 |
| 英文关键词: Micropterus salmoides Aeromonas caviae 16S rRNA Drug sensitive test Virulence genes Histopathology |
| 基金项目:国家自然科学基金(32073006)；中山市第二批社会公益与基础研究项目（2021B2058） |
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| 中文摘要: |
| 【目的】为探究深汕特别合作区某鲈鱼养殖基地大口黑鲈(Micropterus salmoides)突发性死亡原因，揭露部分该豚鼠气单胞菌的生物学特性，为养殖大口黑鲈中的疾病防控与诊治提供理论参考。【方法】从深汕特别合作区某鲈鱼养殖基地的患病大口黑鲈肝脏、脾、肠以及病灶组织分离得到一株优势菌，命名为SZNH-S20230817，随后对分离菌进行了形态学特征观察、生理生化特性鉴定、人工感染实验与组织病理切片分析、药物敏感性测试、MIC和MBC测定、16S rRNA序列、耐药基因以及毒力基因的鉴定来分析其耐药性和病理性。【结果】菌株SZNH-S20230817扩展的16S rRNA序列与 NCBI 数据库上豚鼠气单胞菌(Aeromonas caviae) AP019195具有99.38%同源性，同时携带aer、act、lip和fla 4个毒力基因；该菌生化鉴定吲哚、氧化酶、苯丙氨酸、甘露醇、木糖、精氨酸双水解酶和葡萄糖产酸等结果鉴定为阳性；综合上述结果，确定该菌为豚鼠气单胞菌(Aeromonas caviae)。回归感染发现菌株SZNH-S20230817具有较强致病性，对大口黑鲈的半致死浓度LD50为1.39×107 CFU/mL。药敏实验结果显示，该菌对头孢唑林、卡那霉素、四环素和万古霉素、氨苄西林和克林霉素等12种抗生素耐药，同时携带qnrS、catI、emrB、Sul1、rmtB等13种耐药基因。组织病理学分析表明，菌株SZNH-S20230817感染引起了鱼体脾脏细胞肿胀，游离，肠黏膜断裂破损，绒毛脱落，肾脏细胞坏死，炎症细胞浸润，肝脏细胞呈空泡化等。体外抑菌实验结果显示该菌对大黄和五倍子中草药的MIC和MBC较低，其余7种中草药对该菌的抑菌能力弱。【结论】不同地区的豚鼠气单胞菌间存在耐药基因与毒力基因的差异，但实验结果表明在病理损伤中存在相似性，并且在中药抑制该菌的生长中也表现出相似性，低剂量的大黄和五倍子能够有效抑制该菌的生长，具备良好的预防和抑制效果。 |
| 英文摘要: |
| 【Objective】 In order to investigate the causes of sudden death of largemouth bass (Micropterus salmoides) in a bass culture base in Shenzhen-Shanwei Special Cooperation Zone, and reveal the biological characteristics of part of the guinea Aeromonas caviae, and the theoretical reference was provided for disease prevention, treatment and prevention in breeding largemouth bass.【Method】 A dominant bacterial strain, named SZNH-S20230817, was isolated from the liver, spleen, intestine, and lesion tissues of the diseased largemouth bass in the present study, and the isolate was subsequently subjected to morphological characterisation, physiological and biochemical characterisation, artificial The isolate was then subjected to morphological observation, physiological and biochemical characterization, artificial infection experiment and histopathological section analysis, drug susceptibility test, MIC and MBC determination, 16S rRNA sequence, identification of resistance genes and virulence genes to analyse its drug resistance and pathology.【Result】 The results showed that the extended 16S rRNA sequence of SZNH-S20230817 had 99.38% homology with Aeromonas caviae (Aeromonas caviae) AP019195 on the NCBI database, and also carried four virulence genes, aer, act, lip and fla; the bacterium was biochemically identified with indole, oxidase, phenylalanine, mannitol The results of indole, oxidase, phenylalanine, mannitol, xylose, arginine bis-hydrolysate and glucose acid production were identified as positive; combining the above results, it was determined that the bacterium was Aeromonas caviae (Aeromonas caviae). Regression infection revealed that strain SZNH-S20230817 was highly pathogenic, with an LD50 of 1.39×107 CFU/mL for largemouth bass.The results of drug sensitivity experiments showed that the bacterium was resistant to 12 antibiotics, including cefazolin, kanamycin, tetracycline and vancomycin, ampicillin, and clindamycin, and also carried qnrS, catI, emrB, Sul1, rmtB and 13 other resistance genes. Histopathological analysis showed that infection with strain SZNH-S20230817 caused swelling and freeing of splenocytes, fracture and rupture of intestinal mucosa, shedding of villi, necrosis of renal cells, infiltration of inflammatory cells, and vacuolisation of hepatic cells in the fish. The results of in vitro bacterial inhibition experiments showed that the bacterium had low MIC and MBC against rhubarb and quinquefolium herbs, and the remaining seven herbs were weakly inhibited against the bacterium.【Conclusion】 There are differences in drug resistance genes and virulence genes between Aeromonas guinea-pig from different regions, but the experimental results show similarities in pathological damage and in the inhibition of the growth of the bacterium by traditional Chinese medicines, and the low dose of rhubarb and quinquefolium can inhibit the growth of the bacterium effectively, with good preventive and inhibitory effects. |
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