Phylogenetic relatedness of S. anginosus, S. constellatus, and S. intermedius has been confirmed by rRNA sequence analysis.

[2] The majority of Streptococcus anginosus strains produce acetoin from glucose, ferment lactose, trehalose, salicin, and sucrose, and hydrolyze esculin and arginine.

[4] Streptococcus anginosus is part of the human bacteria flora, but can cause diseases including brain and liver abscesses under certain circumstances.

[3] With S. anginosus blood stream infections (bacteremia) it has been widely reported that the source is often from an abscess.

A case study was reported on a 40-year-old man who frequently drank alcohol and had poor oral hygiene.

Most Streptococcus milleri strains are resistant to bacitracin and nitrofurazone, and sulfonamides are totally ineffective.