斑点叉尾(Ictalunes punctatus)源中间气单胞菌(Aeromonas media)分离鉴定及药敏特性

ISOLATION AND IDENTIFICATION OF AEROMONAS MEDIA FROM ICTALUNES PUNCTATUS AND ITS ANTIBIOTIC SENSITIVITY

从湖南常德某养殖场死亡的斑点叉尾（Ictalunes punctatus）肝脏、肾脏、腹水及血水中分离到一株致病性菌株zy02。对该菌进行了形态特征观察、理化特性测定及分子生物学方法鉴定,用PCR方法同时扩增其16S rDNA和gyrB基因,分析了16S rDNA和gyrB两种基因序列的同源性,并构建了系统发生树。经生理生化测定和16S rDNA与gyrB基因序列分析,zy02株为中间气单胞菌。人工感染该菌后发病鱼表现为与自然发病类似症状,且从组织中再分离的细菌特性与原感染菌相同。腹腔注射后该菌株对斑点叉尾的半致死浓度为3.89×10~6CFU/mL。菌株zy02对多西环素、庆大霉素及左氧氟沙星等高度敏感;对红霉素中度敏感;对阿莫西林、磺胺异噁唑、克林霉素及利福平等5种药物耐药。本研究为斑点叉尾该病防控提供了理论依据。

A bacterial strain zy02 was isolated from Ictalunes punctatus suffered from hemorrhage disease in a mass mortality broke out in an aquaculture field in Changde, Hunan Province during Oct., 2015; and it was identified as Aeromonas media by analyzing biochemical reactions and 16S rDNA and gyrB gene sequence. Artificial affected fish by intraperitoneal zy02-injection showed same symptom as that of natural ones with similar morphological and biochemical characteristics. Therefore, A. media was proved to be the pathogen to I. punctatus and the in LC50 was 3.89× 10^6CFU/mL as determined in the Reed-Muench method. Our antibiotic sensitivity test showed that the isolate was very sensitive to doxycycline, gentamicin, levofloxacin, etc., less sensitive to erythromycin, and not sensitive to amoxicillin, sulfisoxazole, clindamycin, rifampicin etc. This study provides a theoretical basis for the prevention and control of the disease in I. punctatus.