The role of the capsule of the Streptococcus milleri group in its pathogenicity

Shuzo Kanamori, Nobuchika Kusano, Takashi Shinzato, Atsushi Saito

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Study of the pathogenicity of encapsulated strains of the Streptococcus milleri group (SMG) was performed by examination of the ability to cause subcutaneous abscesses in mice and by phagocytosis and phagocytic killing of human polymorphonuclear neutrophils (PMNs) against the organisms. All 3 encapsulated isolates from patients with pneumonia or lung abscess induced abscesses in the mice; however, only 2 of 20 unencapsulated isolates from patients with lung abscess or thoracic empyema did so. The 3 encapsulated strains inhibited more phagocytosis and phagocytic killing of PMNs than the unencapsulated strains. In addition, encapsular material separated from Streptococcus constellatus RZYK001 also inhibited phagocytosis and phagocytic killing in proportion to increasing concentrations of the capsular material. These results suggest that capsular material produced by SMG might be a pathogenic factor.

Original languageEnglish
Pages (from-to)105-109
Number of pages5
JournalJournal of Infection and Chemotherapy
Issue number2
Publication statusPublished - Apr 2004


  • Abscess
  • Capsule
  • Pathogenicity
  • Phagocytosis
  • Streptococcus milleri group

ASJC Scopus subject areas

  • Microbiology (medical)
  • Pharmacology (medical)
  • Infectious Diseases


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