[Etiological characteristics of pyogenes isolated from children with scarlet fever in Tianjin from 2012 to 2016].

To investigate the etiological characteristics of pyogenes that caused scarlet fever from 2012 to 2016 in Tianjin. The subjects were children diagnosed clinically as scarlet fever in Tianjin scarlet fever monitoring hospital from 2012 to 2016. The exclusion criteria were children with scarlet fever who were unable to cooperate with sampling. A total of 575 cases of children's swabs were collected. Biochemical methods were used to isolate and identify the bacteria of pharynx swab, and the PCR method was used to detect the genotyping and superantigen and , and the resistance of the strains to 10 antibiotics was measured by K-B paper method. We compared the carrying status of superantigen genes by different types of GAS and the resistance of all GAS to different antibiotics. There were 5 types (1/11/12/22/89). The dominant types were 12 (52.9%, 100 strains) and 1 (44.4%, 84 strains). The carrying rates of and genes were 21.7% (41 strains) and 76.7% (145 strains), respectively. The gene carrying rate of 1 type GAS was 33.3% (28 strains), which were higher than that of 12 (12% (12 strains)) (χ(2)=12.21, 0.001). The and gene simultaneous carrying rate of 1 type GAS was 27.4% (23 strains), which was higher than that of 12 type (12% (12 strains)) (χ(2)=7.01, 0.008). The percentages of the strains that were resistant to Azithromycin, Erythromycin, Clarithromycin, Clindamycin, Tetracyclin, Levofloxacin and Chloramphenicol were 96.8% (183 strains), 96.3% (182 strains), 92.1% (174 strains), 92.1% (174 strains), 73.0%(138 strains), 2.1% (4 strains) and 1.6% (3 strains), respectively. All isolates were susceptible to Penicillin, Cefazolin and Vancomycin, and there were statistical significance (χ(2)=953.28, 0.001). The dominant types causing scarlet fever are 12 and 1. The frequencies of and in 1 and 12 are different. S.pyrogenes in Tianjin were susceptible to penicillin, cefazolin and vancomycin, but highly resistant to the clindamycin, clarithromycin, erythromycin and azithromycin.