鸡源鼠伤寒沙门菌的分离鉴定、药敏试验与毒力基因检测

Isolation, identification, antimicrobial susceptibility test and virulence genes detection of Salmonella typhimurium from chicken

鼠伤寒沙门菌是一种重要的人兽共患病病原,不仅影响养禽业的健康发展,还对禽类产品安全构成严重威胁,本研究主要是对鸡源鼠伤寒沙门菌进行分离鉴定、药敏试验和毒力基因的测定。首先采集病死产蛋鸡的脾脏组织进行分离培养和染色镜检,以及16S rRNA基因的PCR鉴定,然后用圆纸片扩散法测定分离株对26种药物的敏感性,用PCR方法检测分离株的28个毒力基因。结果显示,分离株在普通营养琼脂和血琼脂培养基上形成灰白色菌落,在麦康凯培养基上为无色菌落,在BS培养基上为黑色带金属光泽的菌落;染色镜检结果显示分离株为革兰阴性的红色短杆菌;16S rRNA基因测序结果显示,分离株与鼠伤寒沙门菌OLF-FSR1-WB-Sparrow-ST-87的相似性为99.86%,与10个鼠伤寒沙门菌参考菌株的同源性介于99.5%~100%;药敏试验结果表明,分离株对环丙沙星最为敏感,抑菌圈直径达30 mm;除sseC基因未检测出外,其余27个毒力基因的测序结果与参考菌株对应毒力基因的相似性介于98.58%~100%。本研究成功从病死产蛋鸡分离鉴定出一株鼠伤寒沙门菌菌株FY2021,为深入研究鼠伤寒沙门菌的致病机理和禽源沙门菌病的防控提供参考依据。

As a critical zoonosis pathogen,Salmonella typhimurium cannot only affects the healthy development of the poultry industry,but also poses a serious threat to the safety of poultry products.The primary purpose of this study was to isolate and identify the pathogen,test the drug sensitivity and detect the virulence genes.Firstly,the spleen tissues of dead laying hens were collected for isolation,culture,microscopic examination,and PCR identification of 16S rRNA gene.Then,antimicrobial susceptibility was determined for the isolated strain to 26 drugs by circular disk diffusion method,while 28 virulence genes were detected by PCR.The isolated strain formed gray colonies on ordinary nutrient agar and blood agar,colorless colonies on MacConkey medium,and black metallic colonies on BS medium.The staining microscopy showed gram-negative,red,and short bacillus.PCR and sequencing for 16S rRNA indicated that,the similarity of the isolated strain was 99.86%compared with S.typhimurium strain OLF-FSR1-WB-Sparrow-ST-87,and the homology ranged from 99.5%to 100%compared with 10 reference strains of S.typhimurium.The susceptibility test showed the strain was highly sensitive to Ciprofloxacin with an inhibition zone of 30 mm.Furthermore,except that the gene of sseC was not be detected,the similarity of the other 27 virulence genes was between 98.58%and 100%,compared with the corresponding virulence genes of the reference strains in GenBank.In conclusion,S.typhimurium strain FY2021 was successfully isolated and identified from the dead layer,which provides a basis for the further study of the pathogenesis of S.typhimurium and the prevention and control of salmonellosis.