黑斑蛙歪头病的病原菌分离鉴定及其感染病理分析

Isolation and Identification of Pathogenic Bacterium and Pathological Lesions of Torticollis Disease in Frog Rana nigromaculata

本研究从具有典型歪头病症状的濒死黑斑蛙(Rana nigromaculata)肝脏中分离到一株优势菌HJS0526,以确定常德地区黑斑蛙歪头病的病原菌及分析其致病机理。通过细菌形态学、生理生化分析、16S rDNA序列比对确定HJS0526菌株为米尔伊丽莎白菌(Elizabethkingia miricola)。人工感染HJS0526菌株14 d后,实验组歪头症状出现率达90%以上,死亡率高于50%,感染症状和自然发病症状基本一致。药物敏感试验结果表明,菌株HJS0526对环丙沙星和氟苯尼考高度敏感,金银花和鱼腥草醇提取液对HJS0526菌株具有极好的抑制效果;组织病理学研究结果显示,HJS0526菌株感染造成黑斑蛙全身多组织器官功能障碍,特别是肝、脾、肾和肺等组织严重损伤,表现为明显充血、出血及细胞变性、坏死。米尔伊丽莎白菌对黑斑蛙具有高致病性,感染后可导致黑斑蛙多组织器官功能损伤而死亡。本研究结果可为预防和控制常德地区由米尔伊丽莎白菌引起的黑斑蛙歪头病提供科学依据。

In order to determine the pathogenic bacterium causing torticollis disease of frog Rana nigromaculata in Changde, Hunan province, a bacterial strain named HJS0526 was isolated from liver of the diseased frog. It was identified as Elizabethkingia miricola.The results of artificial infection test showed the accumulative mortality was over 50% within 14 d post-infection in experimental group. The clinical symptoms of the infected frogs were similar to those observed in naturally infected individuals. The results of drug sensitivity test showed that the HJS0526 strain was highly susceptible to ciprofloxacin and florfenicol. The alcohol extracts of honeysuckle and houttuynia cordata possesses an excellent inhibitory effect on E. miricola. Histopathological observations of infected frogs revealed that HJS0526 strain infected can cause frog local tissues injury, organ dysfunction, especially for liver, spleen, kidney and lung, which showed evident hyperemia, bleeding, cell degeneration, necrosis and inflammatory response. E. miricola is highly pathogenic for frog, and it infected will lead to frog died by damage and functional impairment of major organ. The findings may provide a scientific basis for prevention and control the torticollis disease of frog caused by E. miricola in Changde.