2013—2019年北京市某区儿童感染A组溶血性链球菌分子特征分析

Molecular characteristics of group A Streptococcus circulated in children in a district, Beijing

目的分析2013—2019年北京市某区儿童感染A组溶血性链球菌抗生素敏感性及分子遗传特征。方法使用儿童感染A组溶血性链球菌病原学监测中获得菌株进行全基因组测序,获得菌株多位点序列分型,描述不同年度优势序列型(sequence type,ST),使用resfinder利用基因组数据检测耐药基因,研究耐药表型与耐药基因型之间的关系。结果在234株A组溶血性链球菌中鉴定到7种ST,ST36和ST28构成比分别为48.72%和46.15%;优势耐药基因为ermB(97.44%)、tetM(92.31%),优势耐药基因谱为ermB+tetM共同携带。结论本地区儿童感染A组溶血性链球菌以ST36和ST28为主,其他ST少量分散分布;菌株耐药基因型与耐药表型分布特征一致性好,可以通过耐药基因的存在情况预测耐药表型。

Objective To illustrate the molecular characteristics of group A Streptococcus(GAS)isolated from children in a district,Beijing.Methods Whole genome sequencing of GAS strains isolated from infected children was performed and multilocus sequence typing(MLST)was used to determine the sequence types(STs)of the isolated strains.The annual dominant STs were obtained and minimum spanning trees were reconstructed on STs.Maximum likelihood phylogenetic tree based on SNPs was built up.Antibiotic resistance test was carried out and antibiotic resistance genes were also detected using resfinder based on the whole genome sequence.Results Out of total 234 strains,seven STs were identified.The predominant STs were ST28 and ST36,accounting for 48.72%and 46.15%of total STs.The dominant antibiotic resistance genes were found to be ermB(97.44%)and tetM(92.31%)and the dominant antibiotic resistance gene pattern was ermB+tetM.Seven lineages were determined in the phylogenetic tree based on SNPs in the core genome of 234 strains.Conclusions ST36 and ST28 are the predominant STs in GAS infected children.High consistency between antibiotic resistance genotype and antibiotic resistance phenotype is observed in isolated GAS strains.