摘要
【目的】对广西南宁市郊三塘镇某养殖场患病罗非鱼进行病原菌分离鉴定及药敏试验,旨在找出罗非鱼的发病原因,为该病的有效防治提供依据。【方法】用常规方法从患病濒死罗非鱼脑部分离病原菌,通过人工感染试验确定分离菌株的致病性,用API20 Strep生化鉴定系统和16S rRNA鉴定病原菌,并采用K-B纸片扩散法进行药敏试验。【结果】分离获得的4株革兰氏阳性球菌(GXN01、GXN02、GXN03和GXN04)对健康罗非鱼均有很强的致病性,是导致罗非鱼发病死亡的病原菌,经API20Strep生化鉴定和16SrRNA鉴定均为无乳链球菌(Streptococcusagalactiae),与GenBank上已登录的无乳链球菌JQ039365、JQ039376、JQ990156、JQ039366、JF423948、HQ645984、GU217535菌株高度同源,同源性达99.2%~99.7%,4株分离菌株间也高度同源(99.9%)。药敏试验结果发现,4株无乳链球菌对先锋霉素VI、氧氟沙星、先锋必、盐酸沙拉沙星敏感,但对庆大霉素、氟哌酸、磺胺-6-甲氧嘧啶、磺胺对甲氧嘧啶等具有耐药性。【结论】引起广西南宁市三塘某养殖场罗非鱼发病死亡的病原菌为无乳链球菌,可选用先锋霉素VI、氧氟沙星、先锋必、盐酸沙拉沙星等药物进行防治。
[Objective]Pathogenic bacteria strains were isolated and identified from diseased tilapia cultured in a fish farm in Santang Town, Nanning City, Guangxi. A drug sensitivity test was conducted to seek out the aetiological agent and provide references for effective prevention and control. [Method]The strains were separated from the brain tissue in dying tilapias using routine method. Pathogenicity of the strains was determined by an artificial infection experiment. The strains were identi-fied using API20Strep and the 16S rRNA sequences. K-B was applied to test the drug sensitivity. [Result]Four Gram-positive cocci （GXN01, GXN02,GXN03 and GXN04） possessed strong pathogenicity against healthy tilapia and they might be the aetiological agent causing tilapia to death. The four strains were identified as Streptococcus agalactiae. All the strains shared 99.2%-99.7% similarities with those S. agalactiae strains reported in GenBank （JQ039365,JQ039376,JQ990156, JQ039366, JF423948, HQ645984 and GU217535）. These four strains also shared high similarities（99.9%） with each other. Drug susceptibility test results showed that the four strains were sensitive to ofloxacin, cephalosporinVI, cefobid and sarafloxacin hydrochloric,but resistant to gentamicin, norfloxacin, sulfadoxine-6-methoxymethoxypyrimidine and sulfa-methoxy-pyrimidine. [Conclusion]The deaths of tilapia might be caused by S. agalactiae infection. Four kinds of drugs （CephalosporinVI, Ofloxacin, Cefobid and Sarafloxacin hydrochloric） could be used for prevention and treatment.
出处
《南方农业学报》
CAS
CSCD
北大核心
2014年第3期498-504,共7页
Journal of Southern Agriculture
基金
广西科学研究与技术开发计划项目(桂科攻1123006-4)
广西水产畜牧兽医局专项项目(桂渔牧财[2011]52号
桂渔牧财[2012]30号
桂渔牧财[2013]35号)
南宁市科学研究与技术开发计划项目(20132123)
关键词
罗非鱼
无乳链球菌
分离鉴定
16S
RRNA
药敏试验
tilapia
Streptococcus agalactiae
isolation and identification
165 rl^NA
drug susceptibility test
