Streptococcus


![Phylogenetic tree of Streptococcus species, based on data from PATRIC.[17] 16S groups are indicated by brackets and their key members are highlighted in red.](/uploads/202502/13/Streptococcus_phylogenetic_tree1532.png)
![Common and species-specific genes among Streptococcus sanguinis, S. mutans, and S. pneumoniae. Modified after Xu et al. (2007)[19]](/uploads/202502/13/Streptococcus_gene_overlap1532.png)
Streptococcus is a genus of coccus (spherical) Gram-positive bacteria belonging to the phylum Firmicutes and the order Lactobacillales (lactic acid bacteria). Cell division in this genus occurs along a single axis in these bacteria, thus they grow in chains or pairs, hence the name—from Greek στρεπτός 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.)