Ann Lab Med 2017; 37(4): 297-304
Prevalence of Complement-Mediated Cell Lysis-like Gene (sicG) in Streptococcus dysgalactiae subsp. equisimilis Isolates From Japan (2014–2016)
Takashi Takahashi, M.D.1, Tomohiro Fujita, M.T.1,2, Akiyoshi Shibayama, M.T.1,3, Yuzo Tsuyuki, M.T.1,4, and Haruno Yoshida, M.A.1
Laboratory of Infectious Diseases1, Kitasato Institute for Life Sciences, Kitasato University, Tokyo; Department of Clinical Laboratory2, Kitasato University Medical Center, Kitamoto; Department of Clinical Laboratory3, Mishuku Hospital, Federation of National Public Service and Personnel Mutual Aid Associations, Tokyo; Division of Clinical Laboratory4, Sanritsu Co., Ltd., Yachiyo, Japan
Correspondence to: 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
Received: September 13, 2016; Revised: November 24, 2016; Accepted: February 13, 2017; Published online: July 1, 2017.
© The Korean Society for Laboratory Medicine. All rights reserved.

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Background: Streptococcus dysgalactiae subsp. equisimilis (SDSE; a β-hemolytic streptococcus of human or animal origin) infections are emerging worldwide. We evaluated the clonal distribution of complement-mediated cell lysis-like gene (sicG) among SDSE isolates from three central prefectures of Japan.
Methods: Group G/C β-hemolytic streptococci were collected from three institutions from April 2014 to March 2016. Fifty-five strains (52 from humans and three from animals) were identified as SDSE on the basis of 16S rRNA sequencing data.; they were obtained from 25 sterile (blood, joint fluid, and cerebrospinal fluid) and 30 non-sterile (skin-, respiratory tract-, and genitourinary tract-origin) samples. emm genotyping, multilocus sequence typing, sicG amplification/sequencing, and random amplified polymorphic DNA (RAPD) analysis of sicG-positive strains were performed.
Results: sicG was detected in 30.9% of the isolates (16 human and one canine) and the genes from the 16 human samples (blood, 10; open pus, 3; sputum, 2; throat swab, 1) and one canine sample (open pus) showed the same sequence pattern. All sicG-harboring isolates belonged to clonal complex (CC) 17, and the most prevalent emm type was stG6792 (82.4%). There was a significant association between sicG presence and the development of skin/soft tissue infections. CC17 isolates with sicG could be divided into three subtypes by RAPD analysis.
Conclusions: CC17 SDSE harboring sicG might have spread into three closely-related prefectures in central Japan during 2014–2016. Clonal analysis of isolates from other areas might be needed to monitor potentially virulent strains in humans and animals.
Keywords: Streptococcus dysgalactiae subsp. equisimilis, Complement-mediated cell lysis-like gene, Clonal complex, emm genotype, Skin and soft tissue infections, Random amplified polymorphic DNA analysis, Jap

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