三北地区鱼源气单胞菌的分离鉴定与药敏试验

选取三北地区鲤、鲫、草鱼、大西洋鲑等鱼体内分离到的气单胞菌共16株,结合革兰氏染色、氧化酶反应和分子生物学方法对其进行鉴定后,采用K-B药敏纸片法测定16株菌对10类25种药物的敏感性。结果表明:16株菌均为革兰氏阴性、氧化酶阳性细菌;Blast比对分析发现实验菌株的16S rRNA序列分别与Gen Bank数据库中维氏气单胞菌、嗜水气单胞菌、温和气单胞菌和杀鲑气单胞菌的不同菌株的16S rRNA基因序列同源性较高,相似性达95%以上;系统发育树显示16株菌分别与维氏气单胞菌、嗜水气单胞菌、温和气单胞菌和杀鲑气单胞菌的不同菌株聚为一支,而与肠杆菌、志贺菌和弧菌分支较远,从而判定为维氏气单胞菌、嗜水气单胞菌、温和气单胞菌和杀鲑气单胞菌;16株分离菌中有3株维氏气单胞菌、4株嗜水气单胞菌、3株温和气单胞菌和6株杀鲑气单胞菌;药敏试验中16株气单胞菌对氨苄西林、青霉素G、阿莫西林、三甲氧苄氨啶、复方新诺明、磺胺异噁唑、氯霉素、利福平具有较高的耐药性,耐药率达95%以上,对氟喹诺酮类药物普遍较敏感,不同菌株之间的耐药谱存在很大差异。为气单胞菌的鉴定及三北地区淡水鱼细菌病的药物防治提供科学依据。

Isolation,Identification and Susceptibility Test of Aeromonas from Fish in the Three North Areas of China

16 strains of Aeromonas from Cyprinus carpio,Carassius auratus,Ctenopharyngodon idellus and Atlantic salmon in the three north areas of China were selected,combined with the gram stain,oxidase reaction and molecular biology method for verification,the susceptibility test was used to determine the sensitioity of 16 strains of Aeromonas to 25 kinds of antibiotics.The results showed that 16 isolates were gram negative,oxidase positive bacteria.The analysis the 16S rRNA sequence of the experimental strains by blast with16S rRNA se-quence of different strains of A.veronii,A.hydrophila,A.sobria and A.salmonicida in GenBank database found that the homology of their 16S rRNA gene sequence was pretty high,the similarity was higher than 95%.Phylo-genetic tree showed that the 16 isolates were respectively aggregated with different strains of A.veronii, A.hy-drophila,A.sobria and A.salmonicida into one branch,but the branch was far away from enterobacter, shigella and vibrio ,thus they were confirmed as A.veronii,A.hydrophila,A.sobria and A.salmonicida.From the 16 strains 3 were A.veronii, 4 were A.hydrophila, 3 were A.sobria and 6 were A.salmonicida.The susceptibility test showed:16 strains of Aeromonas had high resistance to ampicillin,penicillin G,amoxicillin,trimethoprim,com-pound,sulfamethoxazole,sulfisoxazole,chloramphenicol,cefoperazone and Rifampicin;the percentage of resist-ance was above 95%,and was generally sensitive to fluoroquinolones,resistant profiles varied considerably a-mong the strains.This study provides scientific basis for the identification of Aeromonas and the prevention and control of bacterial diseases in freshwater fish with drugs in the three north areas of China.