Changes over an 8-year period in Streptococcus pyogenes emm types in pharyngeal isolates from non-invasive infection patients at a pediatric facility

Streptococcus pyogenes, or Group A Streptococcus (GAS), is one of the most common pathogens of bacterial infection in children. GAS can cause such non-serious and non-invasive diseases as pharyngitis and skin infections, as well as serious and invasive diseases like streptococcal toxic shock syndrome. One of the factors that make GAS pathogenic is the type-specific M protein found on the cell surface. In 2008, we examined GAS strains isolated from patients with non-invasive infections at our hospital to analyze the emm types and their characteristics. The present study was conducted 8 years later for comparison. METHODS: The 23 study subjects were in patients or out patients at Nippon Medical School's Tama Nagayama Hospital between 2016 and 2017. A pharyngeal swab were taken from each subjects. Genes encording M proteins were amplified by polymerase chain reaction. RESULTS: The emm type analysis identified emm1 in 11 of the 23 strains and emm12 in 4. The 3 GGS strains carried the M-like protein genes. CONCLUSIONS: In our earlier report, the predominant emm type was emm12, while in the current study, emm1 was the most common. The current study also identified 3 strains of Group G Streptococcus (GGS) among the isolates, which carried a stg245, stg6795, and stg840 gene, respectively. One GAS strain was found to carry stg485, a gene typically associated with GGS rather than GAS.