一株人血源猪链球菌的分离鉴定与毒力基因检测

目的对北京某医院就诊的一例疑似人感染猪链球菌病患者的血液来源菌株进行鉴定与毒力因子检测分析。方法将患者血液分离菌株接种哥伦比亚血琼脂平板,经革兰氏染色镜检、血清凝集试验、VITEK 2Compact微生物分析仪以及基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MS)检测后,再用PCR技术检测猪链球菌种特异性基因(16S rRNA)和猪链球菌2型特异性荚膜多糖编码基因(cps2J)以及多个毒力基因:溶菌酶释放相关蛋白(mrp)、溶血素(sly)、细胞外蛋白因子(ef)、谷氨酸脱氢酶(gdh)、纤粘连蛋白结合蛋白(fbps)、甘油醛-3-磷酸脱氢酶(gapdh)的编码基因和毒力相关基因orf2。结果传统细菌鉴定方法和蛋白质谱技术以及核酸检测方法将这株患者血源性细菌分离株鉴定为猪链球菌2型,该菌株的毒力基因cps2J、sly、ef、gdh、fbps、gapdh和orf2的PCR检测均为阳性,mrp基因为阴性。结论该株人血源细菌分离株为猪链球菌2型sly+/ef+/mrp强毒株。

Identification and virulence analysis of a Streptococcus suis strain isolated from human blood

To identify and analyze the virulence of a bacteria strain isolated from the blood of a patient with suspected Streptococcus suis (S.suis) infection in a hospital of Beijing,we inoculated the bacteria strain isolated from the blood of the patient to the Columbia with sheep blood agar plate,after Gram staining and microscopical examination,serum agglutination test,VITEK 2 Compact microbial identification system test and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) test,S,suis species specific gene 16SrRNA,S.suis species serotype 2 specific virulence gene capsule polysaccharide 2J (cps2J) and virulence gene muramidase-released protein (mrp),hemolysin (sly),extracellular factor protein (ef),glutamate dehydrogenase (gdh) genes,fibronectin-binding protein (fbps),glyceraldehyde-3-phosphate dehydrogenase (gapdh) genes and virulence correlated gene orf2 were further detected by PCR.Results showed that the suspicious bacteria strain of S.suis was identified as S.suis type 2 (S.suis 2) by conventional methods,MALDI-TOF-MS and PCR.PCR results showed that cps2J,sly,ef,gdh,fbps,gapdh and or f2 genes were positive,and mrp gene was negative.In conclusion,the bacteria strain isolated from the patient's blood is sly+/ef+/mrp-virulent S.suis 2.