The Streptococcus anginosus group (also part of the Streptococcus milleri group) comprise 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: