云南师范大学学报（自然科学版）2025，Vol.45Issue(2)：58-64,7.DOI:10.7699/j.ynnu.ns-2025-022
云南美洲牛蛙源无乳链球菌的分离、鉴定及毒力基因检测
Isolation,Identification and Virulence Gene Detection of Streptococcus agalactiae from American Bullfrog(Lithobates catesbeianus)in Yunnan Province
摘要
Abstract
To investigate the pathogenic factors responsible for the mass mortality of American bull-frogs(Lithobates catesbeianus)at a farm in Yunnan Province,an epidemiological survey was conduc-ted,and a dominant bacterial strain was isolated from the spleen,kidney,and liver of diseased bull-frogs.The morphological,physiological,and biochemical characteristics of the isolate were analyzed,a-long with the cloning of virulence gene sequences and determination of minimum inhibitory concentra-tions(MIC).The results revealed an exponential increase in mortality from March to April,indicating a high mortality rate and rapid transmission of the disease.Based on colony morphology,physiological and biochemical traits,and 16S rRNA gene sequencing,the isolate was identified as Streptococcus aga-lactiae.Its virulence genotype was determined as scpB-hylB+bca-bac-lmb-cylE-fbsA+fbsB+ia-gA+cfb+bibA+sip+sodA+rib-pavA+cspA+.MIC testing demonstrated the following values(＞500,＞500,＞500,3.906,7.813,7.813,62.500,＞250,＞250 μg/mL,and 0.781 μg/mL)for sulfame-thoxazole,sulfadiazine,sulfamethazine,florfenicol,norfloxacin,ciprofloxacin hydrochloride,oxolinic acid,neomycin sulfate,thiamphenicol,and ampicillin,respectively.Florfenicol exhibited the lowest MIC(3.906 μg/mL),suggesting its potential as the primary therapeutic agent for S.agulactiae-related dis-eases in bullfrogs.关键词
无乳链球菌/16S rRNA/毒力基因/MICKey words
Streptococcus agalactiae/16S rRNA/Virulence gene/MIC分类
水产学引用本文复制引用
袁茵,戴春祥,李兆丰,毕保良,严晖,高宇..云南美洲牛蛙源无乳链球菌的分离、鉴定及毒力基因检测[J].云南师范大学学报（自然科学版）,2025,45(2):58-64,7.基金项目
云南省应用基础研究计划面上资助项目(2018FB048) （2018FB048）
云南省农业基础研究联合专项资助项目(202101BD070001-119). （202101BD070001-119）
