2株海豚链球菌的分离鉴定及药敏特性分析

Isolation,identification and antibiotic susceptibility analysis of 2 strains of Streptococcus iniae

从河北省石家庄市平山县某养殖场患病鲟鱼和井陉县某养殖场患病鲟鱼体内分别分离获得一株革兰氏阳性菌,对2株菌的形态特征、生理生化特性及16S rDNA序列进行分析,鉴定均为海豚链球菌(Streptococcus iniae);采用微量肉汤稀释法对2菌株分别进行药敏试验,获得各抗生素对菌株的最小抑菌浓度(MIC),发现由井陉患病鲟鱼分离获得的菌株JX-1对硫酸新霉素、甲砜霉素、盐酸多西环素、磺胺甲氧嘧啶钠、磺胺甲噁唑+甲氧苄啶高度敏感,对氟苯尼考中度敏感,对恩诺沙星、氟甲喹耐药;由平山患病鲟鱼分离获得的菌株PS-3对甲砜霉素、盐酸多西环素、磺胺间甲氧嘧啶钠、磺胺甲噁唑+甲氧苄啶高度敏感,对硫酸新霉素、氟苯尼考中度敏感,对恩诺沙星、氟甲喹耐药。2菌株的药敏特性差异主要表现在JX-1对硫酸新霉素中度敏感,PS-3对硫酸新霉素高度敏感。

A Gram positive strain was isolated from diseased sturgeon in a breeding farm of Pingshan County,Shijiazhuang City,Hebei Province and another from diseased sturgeon in Jingxing County,respectively.Morphological characteristics,physiological and biochemical characteristics and 16S rDNA sequence of the 2 strains were analyzed,and they were identified as Streptococcus iniae.Trace broth microdilution method was used for antibiotic susceptibility test to obtain minimal inhibitory concentration(MIC)of various antibiotics on the 2 strains.It was found that the strain isolated from the diseased sturgeon of Jingxing(JX-1)was highly sensitive to neomycin sulfate,thiamphenicol,doxycycline hydrochloride,sodium sulfamonomethoxine,sulfamethoxazole+trimethoprim,moderately sensitive to florfenicol,and resist to enrofloxacin and flumequine.The strain isolated from the diseased sturgeon of Pingshan(PS-3)was highly sensitive to thiamphenicol,doxycycline hydrochloride,sodium sulfamonomethoxine,sulfamethoxazole+trimethoprim,,moderately sensitive to neomycin sulfate and florfenicol,and resist to enrofloxacin and flumequine.The difference of susceptibility characteristic between the 2 strains was mainly manifested as the following:JX-1 was moderately sensitive to neomycin sulfate,while PS-3 was highly sensitive to neomycin sulfate.