Real Dictionary

streptococcus in American English
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
noun: any of several spherical or oval bacteria of the genus Streptococcus, occurring in pairs or chains, certain species of which are pathogenic for humans, causing scarlet fever, tonsillitis, etc.

streptococcus in British English
noun: any Gram-positive spherical bacterium of the genus Streptococcus, typically occurring in chains and including many pathogenic species, such as S. pyogenes, which causes scarlet fever, sore throat, etc: family Lactobacillaceae