山瑞鳖塞氏柠檬酸杆菌的分离鉴定及药物敏感性研究

从患致死性传染病的山瑞鳖(Palea steindachneri)组织中分离到一株细菌(YL090422),对该菌形态、生理生化特征及致病性进行分析,并用BIOLOG自动微生物鉴定系统及16S rDNA序列分析对其进行了鉴定。结果显示:该菌具有较强的致病性,且为发酵型革兰氏阴性短杆菌,无芽胞及荚膜;具有对葡萄糖、精氨酸双水解酶、鸟氨酸脱羧酶、脲酶、西蒙氏柠檬酸盐、丙二酸盐、卫茅醇、吲哚、动力等反应呈阳性,对氧化酶、赖氨酸脱羧酶、苯丙氨酸脱氨酶、V-P反应等呈阴性的特点。BIOLOG自动微生物鉴定系统显示该菌为塞氏柠檬酸杆菌(Citrobacter sedlakii)。16S rDNA序列分析得到1条长度为1464bp的核苷酸序列(GenBank登录号为GU726186),并显示该分离株与塞氏柠檬酸杆菌(C.sedlakii)的同源性达99.9%,且在系统发育树上与C.sedlakii聚为一支。鉴定结果确认菌株YL090422为塞氏柠檬酸杆菌(Citrobacter sedlakii)。药敏试验结果显示:该菌对供试16种抗菌药物中的阿米卡星等3种药物敏感,对头孢哌酮等3种药物中度敏感,对氨苄青霉素等10种抗生素均存在不同程度的耐药。

Isolation and identification of Citrobacter sedlakii from Palea steindachneri and its antibiotic sensitivity

A strain bacterium(YL090422) was isolated from the diseased Palea steindachneri with fatal epidemic disease.Artificial infection proved that the bacterium had strong pathogenicity to examined Palea steindachneri.Its morphological,physiological and biochemical characteristics were studied.The isolated strain is a fermentative bacterium.The bacteria are gram negative,rods,non-capsule and spore;It is glucose-positive,arginine dihydrolase-positive,urease-positive,orinithine decarboxylase-positive,simmon′s citrate-positive,malonate-positive,melampyrin-positive,indole-positive,mobility-positive,oxidase-negative,lysine decarboxylase-negative,phenylalanine deaminase-negative and V-P-negative.The bacterium was identified as Citrobacter sedlakii by BIOLOG automatic microbiological assay system.A sequence of 1464 base pair(bp) was obtained from the bacteria(GenBank accession number GU726186) by 16S rDNA sequence analysis.A phylogenetic tree was constructed by comparing the 16S rDNA sequence of the isolated strain with other relative bacteria strains derived from GenBank databases.The similarities value between strain YL090422 and C.sedlakii is 99.9%,and they constitute a branch in the phylogenetic tree.In conclusion,strain YL090422 was identified as Citrobacter sedlakii.The antibiotic sensitivity test using 16 antimicrobial agents showed that strain YL090422 was sensitive to 3 agents including amikacin,intermediately sensitive to 3 agents including cefoperazone,and was extensively resistant to 10 agents including ampicillin.