Streptococcus

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Streptococcus
Scientific classification
Kingdom: Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Rosenbach, 1884
Species

S. agalactiae
S. anginosus
S. bovis
S. canis
S. constellatus
S. dysgalactiae
S. equi
S. equinus
S. iniae
S. intermedius
S. mitis
S. mutans
S. oralis
S. parasanguinis
S. peroris
S. pneumoniae
S. pyogenes
S. ratti
S. salivarius
S. salivarius ssp. thermophilus
S. sanguinis
S. sobrinus
S. suis
S. uberis
S. vestibularis
S. viridans
S. zooepidemicus

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.