口腔領域感染症分離菌によるマウス腹腔内膿よう形成能の検討 Ｆｕｓｏｂａｃｔｅｒｉｕｍ ｎｕｃｌｅａｔｕｍとＳｔｒｅｐｔｏｃｏｃｃｕｓ ｃｏｎｓｔｅｌｌａｔｕｓ

Abstract

Fusobacterium nucleatum and Streptococcus constellatus are the most common isolates from oral suppurative infections. Reference strains and clinical isolates of F. nucleatum and S. constellatus were studied with regard to their abscess-forming abilities and usefulness as an experimental intra-abdominal abscess model in mice. The abscesses were produced in 80% or more of mice by a simple intraperitoneal injection of F. nucleatum (108 CFU/mouse). Some of the clinical isolates of S. constellatus with a capsule showed very good abscess-forming ability by themselves. Moreover, abscess-forming ability was strikingly enhanced when F. nucleatum and S. constellatus were inoculated concomitantly. Mixed infection led to increased mortality in mice, while infection with F. nucleatum alone did not cause death. These results suggested that F. nucleatum had higher pathogenicity as a causative agent of oral suppurative infections. These findings demonstrated a synergistic effect between F. nucleatum and S. constellatus, and suggested that F. nucleatum might increase the pathogenicity of S. constellatus. It also is easy to induce intra-abdominal abscesses and obtain specimens, making this a quite useful experimental animal model of anaerobic infections.