How beta-hemolyitc streptocci SDSE exhibits pathogenicity

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K07133
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 49050:Bacteriology-related
• Research Institution: Kanazawa University
• Principal Investigator: Ogura Kohei 金沢大学, 新学術創成研究機構, 助教 (00586612)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: レンサ球菌 / 病原性 / 糖尿病 / ヒアルロン酸

Outline of Final Research Achievements

Streptococcus dysgalactiae subsp. equisimilis (SDSE) causes severe invasive streptococcal infections, especially in elderly people and patients with diabetic mellitus. Although SDSE possesses a genome showing about 70% identity to S. pyogenes's one, it remained unclear how SDSE exhibits pathogenicity. Our purpose in this study was to determine pathogenicity characteristics of SDSE. The survival rates of mice injected with SDSE were significantly lower in mice (db/db) with type 2 diabetes compared with non-diabetic mice. Injection of db/db mice with SDSE increased the concentrations of IL-6. SDSE released dramatically high concentrations of hyaluronate-degrading enzymes (hylauronate lyase). We found the lyase plays important roles in nutrient acquisition from host skins, followed by the bacterial pathogenicity damaging host tissues. We revealed that two prevalent types of SDSE isolates exhibited different characteristics in cell wall structures, anti-phagocytosis, and attachment.

Free Research Field

細菌学

Academic Significance and Societal Importance of the Research Achievements

高齢者や基礎疾患保有者に対して高い病原性を示すStreptococcus dysgalactiae subsp. equisimilis (SDSE) については、これまではS.pyogenes に似た性状を示す菌であると考えられていたが、本研究でSDSEが固有の特性を有することが明らかになった。SDSEが糖尿病モデルマウスに対してS. pyogenesと大きく異なる病原性を示すこと、SDSEが人の皮膚ヒアルロン酸を急速に分解し栄養とすること、その他様々なSDSEの新規な特徴を見出した。本研究によって得られた知見は、高病原性レンサ球菌SDSEが引き起こす感染症全容解明に貢献するものである。