Molecular Epidemiology of Group A Streptococcus Isolated from Children in Beijing during 2011 to 2019

Objective This study aimed to examine the characteristics of Group A Streptococcus (GAS) infection and identify the emm genotypes and the superantigen gene of GAS strains isolated from children from 2011 to 2019 in Tongzhou District, Beijing.

Methods Pharyngeal swab samples from children with scarlet fever or pharyngeal infection were collected and tested for GAS. In GAS isolates, emm genotypes and superantigen genes were identified. Logistic regression models were used to explore the correlations between demographic characteristics, clinical manifestations, and GAS infection.

Results In total, 172/1,214 (14.2%) GAS were isolated. The GAS infection rate in children with scarlet fever was 47.5%, higher than 8.5% in children with pharyngeal infection (p < 0.001). The risk of GAS infection was associated with oral mucosal congestion in children with scarlet fever, and older age, tonsillitis, and rash in children with pharyngeal infection. Seven emm genotypes were detected in 164 GAS isolated strains, of which emm12 and emm1 accounted for 47.0 and 46.3%, respectively. Among 112 GAS isolates, the top 5 detection rates of superantigen genes were speF 100.0%, speG 100.0%, speB 98.2%, speC 94.6%, and smeZ 82.1%. Higher proportions of speA, speJ, and speK were detected in emm1 isolates, while speH and speI were more common in emm12 isolates (p < 0.001).

Conclusion The changing predominant type expanded the knowledge of the circulating emm types, which should be considered in future vaccine development.