江西省赣州市首例人感染ST7型猪链球菌病例的病原学分析

Pathogenologic analysis of first case of human sequence type 7 Streptococcus suis infection in Ganzhou City,Jiangxi Province

目的 对赣州市首例人感染ST7型猪链球菌病例开展流行病学调查及病原学分析。方法 对分离的猪链球菌菌株JXGZ1开展分子分型、耐药谱分析、基因组共线性分析和细胞因子检测。结果 特异性基因及毒力基因检测结果为16S r RNA+gapdh+mrp(NA2)+ef-sly+。血清2型,MLST结果为ST7,属于ST7种群谱系5,与广西ST7散发菌株高度同源,含有携带多种耐药基因的128K可移动的基因元件(MGE),包括四环素耐药基因tet(O)-tet(40),大环内脂类耐药基因mef A-mel基因和氨基糖苷类、大环内酯内复合耐药基因aph(3’)-Ⅲa-sat4-erm(B)-ant6ia。菌株对对四环素、红霉素、阿奇霉素、克林霉素、复方新诺明、链霉素及卡那霉素等多种抗生素耐药。刺激宿主产生细胞因子的能力弱于流行型ST7菌株,与高致病型ST1菌株相当。结论 赣州市首例人感染猪链球菌病例为高致病型的序列7型菌株引起的散发病例,对多种抗生素耐药,属于赣州新发传染病。

Objective To investigate the epidemiology and pathogen of the first case infected sequence type(ST)7 Streptococcus suis(S.suis)in Ganzhou City,Jiangxi Province.Methods Molecular typing,antibiotic resistance profile,mauve alignment of the genome and pro-inflammatory cytokine production of isolated JXGZ1 S.suis strain were analyzed.Results The pattern of virulence genes was 16 S r RNA+gapdh+mrp(NA2)+ef-sly+.The strain was identified as serotype 2 and sequence type(ST)7 by using multilocus sequence typing(MLST).It belongs to ST7 population pedigree 5,highly homologous with ST7 emanating strain in Guangxi,and contains 128 K mobile gene element(MGE)carrying multiple drug resistance genes,including tetracycline resistance gene tet(O)-tet(40),macrocyclic lipid resistance gene mef A-mel gene and aminoglycoside,macrolide complex resistance gene aph(3’)-Ⅲa-sat4-erm(B)-ant6 ia.The strain was resistant to many antibiotics,such as p-tetracycline,erythromycin,azithromycin,clindamycin,cotrimoxazole,streptomycin and kanamycin.The ability of stimulating the host to produce cytokines was weaker than that of the epidemic ST7 strain and comparable to that of the highly pathogenic ST1 strain.Conclusion The culprit of emerging human S.suis infection in Ganzhou City,Jiangxi Province was sporadic ST7 strain which possessed high pathogenicity and multiple antibiotic resistances.