宝石鲈嗜水气单胞菌的鉴定及药敏特性

摘要

Two pathogenic bacteria (SS1495 ,and SS1496) were isolated from diseased Scortum barcoo in an aquafarm which was located in Sanshui district of Foshan city , Guangdong province . They were identified by microbial biochemical identification tubes and 16S rDNA sequence analysis ,and the artificial infection experiment and antibiotic susceptibility analysis were performed .The results showed that these two bacteria were facultative anaerobes which were gram negative ,rod in shape ,and motile .They had positive indole ,methyl red and V‐P characteristics ,and utilized glucose ,maltose and mannitol .According to“Bergey’s Manual of Determinative Bacteriology”,the isolates were identified to be Aeromonas hydrophilia based on the morphology ,physiological and biochemical characteristics of the bacteria .The 16S rDNA sequences of the isolates showed a high similarity to that of A .hydrophilia via BLAST network services in NCBI .The median lethal doses for the isolates to healthy S .barcoo were 7 .8 × 104 cfu/g and 3 .9 × 104 cfu/g ,respectively ,indicating they had strong pathogenicity to S .barcoo .The isolates were highly susceptible to cefotaxime ,ciprofloxacin , norfloxacin ,and levofloxacin ,intermediately susceptible to phytomycin ,cephazoline and neomycin ,and resistant to tetracycline ,rifampicin and lincomycin .%从广东省佛山市三水区某养殖场患病濒死的宝石鲈体内分离到两株致病菌（SS1495， SS1496），通过细菌微量生化鉴定管与16S rDNA序列分析对该致病菌进行了鉴定，并进行了人工感染试验和药敏特性分析。结果显示，该菌兼性厌氧，为革兰氏阴性短杆菌，有动力，能利用葡萄糖、麦芽糖、甘露醇，靛基质、甲基红、V‐P试验均为阳性；经菌落形态观察、生理生化特性测定，结合《伯杰氏细菌鉴定手册》鉴定为嗜水气单胞菌，通过PCR扩增该菌16S rDNA序列，经测序及BLAST 比对，结果与嗜水气单胞菌的同源性最高；此两株菌对宝石鲈具有很强的毒力，半致死剂量分别为7．8×104 cf u／g和3．9×104 cf u／g ；该致病菌对头孢噻肟、环丙沙星、诺氟沙星、左氟沙星等抗生素高度敏感，对链霉素、头孢唑林、新霉素中度敏感，对四环素、利福平与林可霉素耐药。