红螯螯虾源布氏柠檬酸杆菌分离鉴定和耐药性分析

Isolation,Identification and Drug Resistance Analysis of Citrobacter braakii from Cherax quadricarinatus

为了确定广西壮族自治区吴圩镇某养殖场红螯螯虾(Cherax quadricarinatus)的潜在致病菌,本试验于2021年1月从该场螯虾肠道分离获得1株优势菌,命名为171215-10,采用形态学观察、生化鉴定、基于16S rDNA序列构建系统进化树、菌株生长曲线测定、人工感染斑马鱼和Kirby-Bauer(K-B)纸片扩散法对分离菌株进行鉴定和分析。结果显示,经鉴定分离菌株为布氏柠檬酸杆菌(Citrobacter braakii),在5~16 h处于指数生长期。人工感染斑马鱼试验结果显示,分离菌株具有较强致病性,注射浓度为1.5×10^(8)CFU/mL布氏柠檬酸杆菌的斑马鱼在2 d内全部死亡。药敏试验结果显示,分离菌株仅对25种抗菌药中的5种敏感,包括诺氟沙星(NFX)、氯霉素(CLM)、多西环素(DOX)、阿米卡星(AMK)和庆大霉素(GEN)。本试验结果为红螯螯虾源布氏柠檬酸杆菌的鉴定及其诊断和治疗提供参考。

In order to identify potential pathogens in Cherax quadricarinatus from a farm in Wuxu Town,Guangxi Zhuang Autonomous Region,China,a dominant strain named 171215-10 was isolated from the crayfish intestines in January 2021.Identification and analysis of the isolated strain were conducted using morphological observation,biochemical identification,construction of phylogenetic tree based on 16S rDNA sequence,bacterial growth curve determination,artificial infection of zebrafish,and Kirby-Bauer(K-B)disk diffusion method.The results showed that the identified isolated strain was Citrobacter braakii,which exhibited exponential growth from 5 to 16 hours.The artificial infection experiment on zebrafish demonstrated that the isolated strain was highly pathogenic,zebrafish injected with a concentration of 1.5×10^(8) CFU/mL of Citrobacter braakii died within 2 days.Drug sensitivity testing revealed that the isolated strain was sensitive to only 5 out of 25 antibacterial drugs,including norfloxacin(NFX),chloramphenicol(CLM),doxycycline(DOX),amikacin(AMK),and gentamicin(GEN).The results of this study provide reference information for the identification,diagnosis,and treatment of Citrobacter braakii from Cherax quadricarinatus.