Objective: To analyze the characteristics of super-antigen (SAg) of group A Streptococcus pyogenes (GAS), isolated from patients with scarlet fever or pharyngeal infections in Beijing between 2015-2017. Methods: Throat swab specimens from patients with scarlet fever or pharyngeal infections were collected and tested for GAS. Eleven currently known SAg genes including SpeA, speC, speG, speH, speI, speJ, speK, speL, speM, smeZ and ssa were tested by real-time PCR while M protein genes (emm genes) were amplified and sequenced by PCR. Results: A total of 377 GAS were isolated from 6 801 throat swab specimens, with the positive rate as 5.5%. There were obvious changes noticed among speC, speG, speH and speK in three years. A total of 45 SAg genes profiles were observed, according to the SAgs inclusion. There were significant differences appeared in the frequencies among two of the highest SAg genes profiles between emm1 and emm12 strains (χ(2)=38.196, P<0.001; χ(2)=72.310, P<0.001). There also appeared significant differences in the frequencies of speA, speH, speI and speJ between emm1 and emm12 strains (χ(2)=146.154, P<0.001; χ(2)=52.31, P<0.001; χ(2)=58.43, P<0.001; χ(2)=144.70, P<0.001). Conclusions: Obvious changes were noticed among SAg genes including speC, speG, speH and speK from patients with scarlet fever or pharyngeal infections in Beijing between 2015-2017. SAg genes including speA, speH, speI and speJ appeared to be associated with the emm 1 and emm 12 strains. More kinds of SAg genes profiles were isolated form GAS but with no significant differences seen in the main SAg genes profiles, during the epidemic period.
目的： 分析2015－2017年北京市猩红热及咽部感染患者A组链球菌（GAS）超抗原基因特征。 方法： 采集猩红热及咽部感染患者咽拭子标本进行GAS分离鉴定，采用实时荧光PCR法检测超抗原基因（speA、speC、speG、speH、speI、speJ、speK、speL、speM、smeZ和ssa），PCR法扩增后测序确定GAS的emm基因型别。 结果： 2015年5月至2017年7月采集的6 801份咽拭子标本中共分离到377株GAS菌株（阳性率5.5%）。超抗原基因speC、speG、speH和speK的检出率3年间出现较明显变化。共检测到45种超抗原基因谱，占比较高的2种超抗原基因谱在emm1和emm12型间分布差异均有统计学意义（χ(2)=38.196，P<0.001；χ(2)=72.310，P<0.001）。超抗原speA、speH、speI和speJ在emm1和emm12型GAS间分布差异均有统计学意义（χ(2)=146.154，P<0.001；χ(2)=52.31，P<0.001；χ(2)=58.43，P<0.001；χ(2)=144.70，P<0.001）。 结论： 2015－2017年北京市猩红热及咽部感染患者GAS超抗原基因speC、speG、speH和speK的检出率有较明显变化，speA、speH、speI和speJ在emm1和emm12基因型之间的分布存在差异，GAS菌株所携带的超抗原基因谱更宽，但主要流行谱未发生改变。.
Keywords: Group A Streptococcus pyogenes; Pharyngeal infection; Scarlet fever; Superantigen; emm genes.