any of a genus (Streptococcus) of spherical, Gram-positive bacteria that divide in only one plane and occur generally in chains: some species cause various serious diseases
A round to ovoid, gram-positive, often pathogenic bacterium of the genus Streptococcus that occurs in pairs or chains, many species of which destroy red blood cells and cause various diseases in humans, including erysipelas, scarlet fever, and strep throat.