杂交鲟体表溃疡病的病原及药敏研究

Study on the Pathogen and Drug Susceptibility of Surface Ulcer of Hybrid Sturgeon

经常规细菌分离,从自然发生体表溃疡病的杂交鲟（西伯利亚鲟Acipenser baerii♂×施氏鲟A.schrenckii♀）中分离到1株病原菌K070401。该菌株可在TSA平板上生长,菌落半透明,1.5~2.0mm大小,边缘光滑,中央凸起。该菌革兰氏染色阴性,显微镜下可见其呈短杆状,两头钝圆,大多数细菌单独存在,少数细菌成对甚至成链存在。该菌葡萄糖氧化发酵阳性,氧化酶检测阳性,0%NaCl生长,脂酶阳性。能利用甘露醇,具运动性,能发酵麦芽糖,不产生H2S,葡萄糖产酸阳性,葡萄糖产气阳性,精氨酸双水解酶阳性,DNA酶阳性,鸟氨酸脱羧阴性,还原硝酸盐。该菌对罗美沙星、磺胺异噁唑、氯霉素、阿奇霉素敏感,对克拉霉素、强力霉素、链霉素、美满霉素较敏感,对氨苄青霉素、古霉素、阿莫西林不敏感。应用细菌通用PCR引物,扩增出K070401菌株的16S rDNA的互补DNA片段,该片段大小为1591bp。将获得的序列在RDP数据库进行在线Classifer。结果表明,该菌属于气单胞菌属的细菌,再将获得的序列与GenBank中已报道的的嗜水气单胞菌16S rDNA序列采用DNAstar软件进行多序列比对分析和构建系统发育树。结果证实,K070401分离株与其他嗜水气单胞菌形成1个簇群,同源性高达为99.2%以上,故确定该菌为嗜水气单胞菌（Aeromonas hydrophilia）。

By aetiology study,a pathogenic bacterium(K070401) was isolated from muscular ulcer of natural diseased hybrid sturgeon(Acipenser baerii♂×A.schrenckii♀).The bacterium colony on the TSA medium showed 1.5～2.0mm size,edge slick,center protuberant and translucent.The bacterium was gram negative,rods,both ends circular,mostly exist solely,but sometimes exist in pairs or even in chains.The main biochemical characteristics are summarized as follows: glucose oxidization-positive,xidase-positive,lipase-positive,mobility-positive,altose-positive,mannite-positive,arginine-diphydrolase-positive,DNase-positive,ornithine decarboxylase-negtive,nitrate deoxidization-positive,ornithine decarboxylase-negative,H2S-negative.It produced gas acid by means of glucose,and could survive in TSB medium with no sodium chloride.The bacterial were very sensitive to lomefloxacin,gantrisin,azithromycin;less sensitive to clarithromycin,doxycycline,straptomycin,minocycline;non-sensitive to ampicillin,vancomycin,amoxicillin.A 1591bp 16S rDNA complementary fragment of K070401 was checked by amplification using bacteria general PCR primer.The sequence classifer in RDP Database suggested that it belonged to Aeromonas.A phylogenetic tree was constructed by comparing the 16S rDNA sequence of the isolated strain(GenBank) with other relative bacteria species in the GenBank databases.The homology between strain K070401 and other Aeromonas hydrophila was 99.2%.according to phylogenetic analysis,the isolated strain(K070401) was identified as Aeromonas hydrophila.