-Original-

Change during an 8-Year Period in Streptococcus Pyogenes emm Types in Pharyngeal Isolates from Children with Noninvasive Infections

Toshinari Okabe¹, Yoshihiko Norose², Masatoshi Hida¹, Sachiyo Takeda¹, Masato Takase¹, Yoshiko Suzuki³ and Hisashi Ohkuni⁴

¹Department of Pediatrics, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
²Department of Microbiology and Immunology, Nippon Medical School, Tokyo, Japan
³Clinical Laboratory, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
⁴Health Sciences Research Institute East Japan, Saitama, Japan

Background: Streptococcus pyogenes, or group A streptococcus (GAS), is one of the most common bacterial pathogens in children. GAS can cause such nonserious and noninvasive diseases as pharyngitis and skin infection, as well as serious, invasive diseases like streptococcal toxic shock syndrome. One factor that makes GAS pathogenic is the type-specific M protein on its cell surface. To identify emm types and their characteristics, we previously examined GAS strains isolated from children with noninvasive infections at our hospital. The present study was conducted 8 years later, for comparison.
Methods: The 23 participants were inpatients and outpatients at Nippon Medical School Tama Nagayama Hospital during 2016 and 2017. A pharyngeal swab specimen was obtained from each child, and genes encoding M proteins were amplified by polymerase chain reaction.
Results: emm type analysis identified emm1 in 11 of the 23 strains and emm12 in 4. Three group G streptococcus (GGS) strains carried M-like protein genes.
Conclusions: The predominant emm type was emm12 in our previous report and emm1 in this study. This study also identified 3 GGS strains among the isolates, which carried either the stg245, stg6795, or stg840 M-like protein gene. One GAS strain carried stg485, a gene associated with GGS rather than GAS.

J Nippon Med Sch 2020; 87: 211-214

Keywords
Streptococcus pyogenes, dominant emm, pharyngitis, children

Correspondence to
Toshinari Okabe, Department of Pediatrics, Nippon Medical School Tama Nagayama Hospital, 1-7-1 Nagayama, Tama, Tokyo 206-8512, Japan
tokabe1110@gmail.com

Received, June 21, 2019
Accepted, December 25, 2019