【摘要】 目的系统分析鉴定南京地区脑膜炎型猪链球菌感染病人脑脊液分离株07NJH06病原生物学特性。方法采集患者脑脊液,进行细菌分离和培养,观察菌体显微形态,通过免疫凝集试验和PCR方法对分离物进行种属鉴定及毒力因子基因携带情况分析,纸片法测定菌株药物敏感性,采用小白鼠和仔猪模型评估分离菌株的致病特性。结果从病人脑脊液分离到1株革兰阳性链球菌,经免疫学、生物化学及分子生物学方法系统鉴定为2型猪链球菌(命名为07NJH06),毒力基因型为cps2J+mrp+epf+sly+gdh+fbp+srtA+,未获得含有完整毒力岛PAI89k的证据,该岛两侧边缘反向重复区靶基因以及岛内二元调控系统SalK/SalR均未检出,但针对岛内3个独立的镶嵌结构区代表基因进行扩增,其中2个结构区代表基因(05SSU0942和05SSU0965)得到特异性扩增;药敏试验显示,07NJH06株对青霉素、万古霉素等抗生素敏感,对四环素、头孢噻肟钠等抗生素耐药;动物感染试验显示,07NJH06株对小鼠和猪仔有致病性,毒力较国内暴发流行强致病株05ZYH33弱,与国际参考株毒力相当。结论07NJH06株为致病性2型猪链球菌,基本生物学特性、主要毒力基因型与既往国内暴发现场分离株相似,但不含有完整的毒力岛PAI89k基因结构,系统掌握该菌遗传信息对于阐明国内强毒株遗传进化规律有重要价值。更多还原

【Abstract】 Objective To identify a human isolate of encephalomeningitis-causing Streptococcus suis serotype 2(S.suis 2,SS2).Methods The bacterial isolate was examined using microscopy,a slide agglutination test,and a multiplex-PCR assay.Pig infection experiments and an antibiotic sensitivity test were performed.Mice and piglets were infected with the isolated bacterium to determine its virulence. Results Multiple sources of evidence identified the cerebrospinal fluid isolate,namely 07NJH06,as SS2,with seven putative virulence factor genes,including gdh,mrp,epf,suilysin,fbp,srtA,and cps2J.PCR tests indicated that the pathogenicity island PAI89K was absent in the genome of the 07NJH06 strain,but two disjunction genes(05SSU0942 and 05SSU0965)within PAI89K were detected.The isolate was sensitive to penicillin-G and vancomycin and resistant to tetracycline and cefotaxime sodium.Furthermore,infection experiments indicated the isolate was virulent in murine and swine models of infection,and it had less virulence than the endemic strain 05ZYH33.Conclusion The isolated 07NJH06 is a virulent strain of SS2 which differs from the highly invasive strain 05ZYH33.This identification of 07NJH06 will facilitate an understanding of the genesis of PAI89K and the development of effective strategies to combat highly pathogenic SS2 infections.更多还原