【摘要】 从病猪肺组织中分离出1株链球菌，通过形态观察、16S rRNA基因测序、多位点序列分型(MLST)等方法对其进行分子分型鉴定，通过小鼠感染试验、毒力基因筛查、生物被膜形成能力、抗生素和中药药敏试验研究分离菌株的致病性和耐药性。结果:分离菌株为革兰阳性，电镜下可见连续排列成链状的卵圆形菌体; PCR和16S rRNA基因系统发育树分析确定其属于猪链球菌血清型3型，命名为猪链球菌GZYZ0831;分离菌株GZYZ0831的序列分型为ST117，携带猪链球菌表面抗原(sao)、细菌转铁蛋白结合蛋白(Tbp)、甘油醛-3-磷酸脱氢酶(GAPDH)、毒力相关序列第二开放阅读框(orf2)和溶菌酶释放相关蛋白(mrp)这5种毒力基因，呈α溶血;感染后可导致小鼠肺脏、脾脏和肝脏等多个器官不同程度的病变。GZYZ0831为产金属β-内酰胺酶的多重耐药菌株，携带β-内酰胺酶耐药基因blaTEM和四环素耐药基因tet O，对阿奇霉素、红霉素、克拉霉素、庆大霉素等17种药物耐药，对中药黄连与板蓝根敏感。综上，本研究系统性分析了1株猪链球菌3型ST117菌株的生物学特性，为其致病机制和耐药机制研究提供科学依据，并对猪链球菌感染的中药防控策略制定提供参考。更多还原

【Abstract】 One Streptococcus strain was isolated from the lung tissue of diseased pigs,and its molecular typing identification was performed through morphological observation,16S rRNA gene sequencing,and multilocus sequence typing( MLST). The pathogenicity and drug resistance of the isolated strain were studied via mouse infection experiments,virulence gene screening,biofilm formation ability tests,and drug sensitivity tests on antibiotics and traditional Chinese medicines( TCMs). The results showed that the isolated strain was Gram-positive,with oval-shaped bacterial cells arranged in chains observed under electron microscopy. PCR and 16S rRNA gene phylogenetic tree analysis identified it as Streptococcus suis serotype 3,designated as Streptococcus suis GZYZ0831. The sequence type of isolate GZYZ0831 was ST117,which carried five virulence genes: the surface antigen gene( sao),the bacterial transferrin-binding protein gene( Tbp),the glyceraldehyde-3-phosphate dehydrogenase gene( GAPDH),the virulence-associated sequence second open reading frame( orf2),and the muramidasereleased protein gene( mrp); and which exhibited α-hemolysis. Infection in mice caused varying degrees of pathological lesions in multiple organs including the lungs,spleen,and liver. GZYZ0831 was a multidrug-resistant strain producing metallo-β-lactamases( MBLs),carrying the resistance genes bla TEM and tet O. It possessed resistance to 17 antibiotics,including azithromycin,erythromycin,clarithromycin,and gentamicin,but was sensitive to the Chinese herbal medicines Coptidis rhizoma and Isatidis radix. This study systematically analyzed the biological characteristics of Streptococcus suis serotype 3 ST117 strain,providing scientific basis for research on the pathogenic and drug resistance mechanisms of Streptococcus suis,and serving as reference for the formulation of TCMs prevention and control strategies against Streptococcus suis infection.更多还原