Ann Lab Med 2018; 38(3): 212-219  
Molecular Epidemiological Features and Antibiotic Susceptibility Patterns of Streptococcus dysgalactiae subsp. equisimilis Isolates from Korea and Japan
Sunjoo Kim, M.D.1, Jung-Hyun Byun, M.D.1*, Hyunwoong Park, M.D.1, Jaehyeon Lee, M.D.2, Hye Soo Lee, M.D.2, Haruno Yoshida, M.A.3, Akiyoshi Shibayama, M.T.3, Tomohiro Fujita, M.T.3, Yuzo Tsuyuki, M.T.3, and Takashi Takahashi, M.D.3
Department of Laboratory Medicine1, Gyeongsang National University College of Medicine, Jinju, Korea; Department of Laboratory Medicine2, Chonbuk National University School of Medicine, Jeonju, Korea; Laboratory of Infectious Diseases3, Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan
Corresponding author: Takashi Takahashi
Laboratory of Infectious Diseases, Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
Tel: +81-3-5791-6428
Fax: +81-3-5791-6441
*The present affiliation is Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
Received: July 28, 2017; Revised: September 2, 2017; Accepted: January 5, 2018; Published online: May 1, 2018.
© Korean Society for Laboratory Medicine. All rights reserved.

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Background: The molecular characterization of Streptococcus dysgalactiae subsp. equisimilis (SDSE) has not yet been performed in Korea. This study aimed to find the differences or similarities in the clinical features, molecular epidemiological findings, and antimicrobial resistance patterns of SDSE from two countries (Korea and Japan).
Methods: SDSE isolates were collected from Korea (N=69) from 2012-2016 and Japan (N=71) from 2014-2016. Clinical characteristics, emm genotypes, and sequence types (STs) were compared. Microdilution tests were performed using different antimicrobials, and their resistance determinants were screened.
Results: Median ages were 69 years in Korea and 76 years in Japan. The most common underlying diseases were diabetes and malignancy. Blood-derived isolates comprised 36.2% and 50.7% of Korean and Japanese isolates, respectively; mortality was not different between the two groups (5.8% vs 9.9%, P =0.53). Among Korean isolates with 20 different combined ST-emm types, ST127-stG245 (N=16), ST128-stG485 (N=10), and ST138-stG652 (N=8) were prevalent. Among Japanese isolates with 29 different combined types, ST17-stG6792 (N=11), ST29-stG485 (N=7), and ST205-stG6792 (N=6) were prevalent. Resistance rates to erythromycin, clindamycin, and minocycline were 34.8%, 17.4%, and 30.4% in Korea and 28.2%, 14.1%, and 21.4% in Japan, respectively.
Conclusions: SDSE infections commonly occurred in elderly persons with underlying diseases. There was a significant difference in the distribution of ST-emm types between the two countries. Antimicrobial resistance rates were comparable with different frequencies of resistance determinants in each country.
Keywords: Streptococcus dysgalactiae subsp. equisimilis, emm genotyping, Multilocus sequence typing, Antimicrobial resistance

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