牛蛙米尔伊丽莎白菌的分离、鉴定与特性分析

从广州番禺某养殖场患“歪头病”的牛蛙(Lithobates catesbeiana)体内脑组织中分离到1株致病菌MEYL-1. 对分离菌株采用细胞形态学、生化特性分析结合16S rDNA 和gyrB基因分子分析，判定所分离菌为米尔伊丽莎白菌（Elizabethkingia miricola）. 采用菌株MEYL-1人工回归感染，显示健康牛蛙注射1×10^8 CFU·mL-1的分离菌株可复制自然发病相似的“歪头”、“白内障”等症状，并且患病蛙中再分离到的致病菌与感染菌株相同. 综合理化特性分析、基因分子鉴定、回归感染实验可基本判定所患歪头病牛蛙病原为MEYL-1（米尔伊丽莎白菌）. 对19种常用药物敏感分析发现分离株MEYL-1对其中4种药物敏感，7种药物中度敏感，对另外8种药物耐受. 本研究通过对“歪头病”的牛蛙菌株的分离鉴定和药物敏感试验，明确了米尔伊丽莎白菌是引起其患病的病原，研究结果将为米尔伊丽莎白菌病的致病机制研究及牛蛙歪头病的防治提供参考依据.

Isolation,identification and characterization of Elizabethkingia miricola from Lithobates catesbeiana

Bacteria pathogens were isolated from brain tissue of diseased American bullfrog (Lithobates catesbeiana) cultured in farms of Guangdong provinces. One bacteria strain with strong virulence was chosen for identifications. The morphological, biochemical and physiological characteristics, phylogenetic analysis of the isolate was achieved by using conventional method, BD PhoenixTM M50 Automated Microbiology System, 16S rDNA and gyrB genes sequence analysis, the characteristics of the isolated strain were in accordance with those of Elizabethkingia miricola. The virulent tests were carried out by using the pure culture of the isolated strain artificially infected American bullfrog with the concentration of 1×10^8 CFU·mL -1, the result indicated that the isolated strain could infected and caused the same typical wry head symptom as nature infected frog. The morphological and biochemical characteristics of the re-isolated bacteria from the artificially infected diseased frog were the same as those of the original infected bacteria. Antibiotic sensitivity assays showed that among 19 antibiotics tested 4 were sensitive, 8 were tolerant. This experiment successfully isolated a single strain of Elizabethkingia miricola, which provided a scientific basis for the prevention and treatment of American bullfrog infected with Elizabethkingia miricola.