患病大鲵中弗氏柠檬酸杆菌的分离与鉴定

Isolation and identification of Citrobacter freundii from diseased giant salamander，Andrias davidianus

摘要:

摘要:【目的】确定导致大鲵(Andrias davidianus)细菌性感染死亡的病原。【方法】从大鲵肝脏中分离细菌，通过Biolog 微生物自动鉴定系统及分子生物学方法对纯培养的细菌进行鉴定，再用大鲵和鲫鱼分别进行人工感染试验，以确定分离菌的致病性，同时对分离到的病原菌进行药物敏感试验。【结果】从患病大鲵肝脏中分离到一株致病菌JZ01，经人工感染健康大鲵，可复制与自然发病相同的症状，且从人工感染病鲵体内再次分离到相同的病原菌。该致病菌对健康鲫鱼也有致病性。经Biolog 微生物自动鉴定系统的鉴定，以及进一步的16S rDNA 基因序列和系统发育分析都表明，此致病菌为弗氏柠檬酸杆菌。药物敏感性试验表明，该菌株对氨曲南、头孢三嗪、先锋噻肟等9 种药物高度敏感。【结论】弗氏柠檬酸杆菌是大鲵的一种致病菌。本文在国内外首次报道了该菌对大鲵具有致病性。

Abstract:

Abstract: ［Objective］To determine the pathogenic bacterium infecting giant salamander (Andrias davidianus). ［Methods］Bacterium was isolated from the liver of diseased Chinese giant salamander and identified by the Biolog Microbial Identification System and molecular biology method． Healthy Chinese giant salamander and crucian carp were used for experimental infection with bacterial suspension． ［Results］A bacterial strain JZ01 was isolated and identified from diseased giant salamander． Infection with the bacterial suspension to healthy giant salamander could reproduce the diseased symptoms as occurred naturally and the same bacterium could be recovered from these infected giant salamanders．The isolated bacterium also has certain pathogenicity to crucian carp． Identification by the Biolog Microbial Identification System，and further 16S rDNA sequence and phylogenetic analysis demonstrated that the bacterium isolated from diseased giant salamander was Citrobacter freundii． The susceptibility test to antibiotics demonstrated that the bacterial strain JZ01 was susceptible to aztreonam，cefepime and cefotamine． ［Conclusion］Citrobacter freundii is a pathogen for cultured Chinese giant salamander．