乌鳢(Channa argus)源摩氏摩根菌(Morganella morganii)的分离、鉴定及药敏特性

摘要

Isolation,identification and drug sensitivity test were performed on the pathogen of Channa argus which were suffering from disease in an aquatic farm in Nanchang in order to provide references to effectively prevent and control disease.In this study,a bacterial strain JX15 was isolated from the liver,kidney,spleen,ascites and ulcera-ted muscle of dying C.argus with the routine separation methods,and identified by morphological observation,phys-icochemical properties test and molecular biology methods.Moreover, the 16S rRNA and gyrB gene of strain JX15 were amplified and the homology of 16S rRNA and gyrB gene sequences were analyzed,and the phylogenetic tree was constructed.Additionally,an experimental infection test by intraperitoneal injection with isolate was studied, and drug sensitivity test was conducted using K-B paper diffusion method.The results showed that the isolate was identi-fied as Morganella morganii by analyzing biochemical reactions,16S rRNA and gyrB gene sequences.The fish intra-peritoneally-injected with the strain JX15 showed like ones infected by M.morganii naturally.The isolate from artifi-cially-infected fish showed similar morphological and biochemical characteristics to those from naturally infected fish. Therefore,M.morganii was pathogen to C.argus with similar clinical signs as naturally diseased fish.The LD50of the strain JX15 to C.argus was 3.4×105cfu·g-1according to the Reed-Muench method.Additionally,the results from drug sensitivity test showed that strain JX 15 was highly sensitive to 7 medicines,such as florfenicol, norfloxa-cin,cefotaxime and some else drugs,and it was medium sensitive to furazolidone,chloramphenicol,kanamycin,and streptomycin,but it was resistance to 11 medicines, including ciprofloxacin, oxacillin, penicillin and other durgs. This study proved that the disease in C.argus from an aquatic farm in Nanchang,Jiangxi Province was caused by M. morganii,and this disease could be treated by six medicaments, i.e.florfenicol, cefotaxime, neomycin, tobramy-cin,gentamicin and amikacin.%对患病乌鳢(Channa argus)进行病原分离、鉴定及药敏试验,为乌鳢病害防控提供参考.从江西南昌某养殖场发病的乌鳢肝、肾、脾和溃烂肌肉中分离到一株病原菌JX15,对JX15株进行形态学观察、理化特性测定及分子生物学方法鉴定,并对JX15株进行人工感染试验和药敏试验.理化特性测定和16S rRNA与gyrB[DNA促旋酶(gyrase)B亚基]基因序列分析表明,JX15株被鉴定为摩氏摩根菌.病理学和致病性试验显示,病鱼肝、肾、脾及溃烂皮肤肌肉等组织器官具有典型病理变化,人工感染的乌鳢出现与自然发病类似症状,且从发病乌鳢体内分离到与菌株JX15一致的菌株,可以断定菌株JX15是本次乌鳢发病的病原菌,其LD50为3.4×105cfu·g-1.JX15株对氟苯尼考、诺氟沙星及头孢噻肟等7种药物高度敏感,对呋喃唑酮、氯霉素、卡那霉素及链霉素4种药物中度敏感;对环丙沙星、苯唑西林及青霉素等11种药物耐药.本研究证明了江西南昌某养殖场的乌鳢溃烂病是由摩氏摩根菌感染所引起的,可选用氟苯尼考、头孢噻肟、新霉素、妥布霉素、庆大霉素、阿米卡星等6种药物进行治疗.