[Study on the super-antigen genes of group A strains isolated from patients with scarlet fever and pharyngeal infection, in Beijing, 2015-2017].

To analyze the characteristics of super-antigen (SAg) of group A (GAS), isolated from patients with scarlet fever or pharyngeal infections in Beijing between 2015-2017. Throat swab specimens from patients with scarlet fever or pharyngeal infections were collected and tested for GAS. Eleven currently known SAg genes including ACGHIJ, KLMZ and were tested by real-time PCR while M protein genes ( genes) were amplified and sequenced by PCR. 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 C, G, H and K 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 1 and 12 strains ((2)=38.196, <0.001; (2)=72.310, <0.001). There also appeared significant differences in the frequencies of A, H, I and J between 1 and 12 strains ((2)=146.154, <0.001; (2)=52.31, <0.001; (2)=58.43, <0.001; (2)=144.70, <0.001). Obvious changes were noticed among SAg genes including C, G, H and K from patients with scarlet fever or pharyngeal infections in Beijing between 2015-2017. SAg genes including A, H, I and J appeared to be associated with the 1 and 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.