Genetic Diversity in Streptococcus dysgalactiae subsp. equisimilis Isolates from Patients with Invasive and Noninvasive Infections in a Japanese University Hospital (2014-2015).

Streptococcus dysgalactiae subsp. equisimilis (SDSE) isolates with β-hemolysis and carbohydrate groups G or C are increasingly recovered from invasive infections in Japan. The aim of this study was to determine the epidemiological characteristics of SDSE isolates circulating locally among patients with invasive and noninvasive infections. We selected groups G/C β-hemolytic streptococci from a repository at the Clinical Laboratory of Kitasato University Medical Center, from May 2014 through April 2015. Thirteen isolates were identified as SDSE based on the data from API-20 Strep and 16S rRNA sequencing. The samples were from 7 sterile specimens (blood) and 6 non-sterile specimens (pus/sputum/vaginal secretion). Information about the patients with invasive or noninvasive SDSE infections was retrieved from their medical charts. We performed emm genotyping, multilocus sequence typing, a dendrogram analysis of the samples using pulsed-field gel electrophoresis (PFGE), and amplifications of the streptococcal inhibitor of a complement-mediated cell lysis-like gene (sicG) and antimicrobial resistance determinants. We identified 8 different emm genotypes, 8 different sequence types, including 4 novel types, 9 different groups in the PFGE dendrogram, the presence or absence of sicG, and 4 different resistance genotypes. Our observations indicate genetic diversity in SDSE isolates from patients with invasive and noninvasive infections in a Japanese university hospital (2014-2015).