Streptococcus - Wikipedia

Streptococcus are spherical, gram-positive bacteria. They are included among the Firmicutes. These bacteria grow in chains or pairs, with cell division occurring only along one axis. In this sense they are contrasted with Staphylococcus, which divides along several axes, generating a "cluster" of cells, which resemble clusters of grapes.

Members of the genus Streptococcus which cause disease include:

Group A Streptococci (Streptococcus pyogenes) which causes strep throat
Group B Streptococci (Streptococcus agalactiae[?]) which causes meningitis in neonates and the elderly, with occasional systemic bacteremia.
Group D Streptococci[?] (S. faecalis, S. faecium, S. durans, S. avium, S. bovis)