streptococcus is a genus of spherical gram-positive bacteria belonging to the phylum firmicutes and the lactic acid bacteria group. they are cocci, meaning that they are shaped like spheres or circles. cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name from greek στρεπτος "streptos", meaning easily bent or twisted, like a chain (twisted chain). contrast this with staphylococci, which divide along multiple axes and generate grape-like clusters of cells. streptococci are oxidase and catalase-negative, and many are facultative anaerobes.