Streptococcus anginosus group

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The Streptococcus anginosus group (also part of the Streptococcus milleri group) comprise of a subgroup of viridans streptococci which are gram-positive, catalase-negative bacteria.

There are three distinct main streptococcal species and several subspecies:

  • S. anginosus: has two subspecies
    • S. anginosus subsp anginosus
    • S. anginosus subsp whileyi
  • S. intermedius
  • S constellatus:  three subspecies
    • S. constellatus subsp constellatus
    • S. constellatus subsp pharyngis
    • S. constellatus subsp viborgensis

A characteristic of the S. anginosus group that sets them apart from other pathogenic streptococci such as S. pyogenes (group A Streptococcus) and S. agalactiae (group B Streptococcus) is their ability to cause abscesses.

They can infect various organ systems which include: