page_title: Streptococcus
section_title: Molecular taxonomy and phylogenetics
hierarchical_section_title: Streptococcus / Molecular taxonomy and phylogenetics
caption_attribution_description: English: Phylogenetic tree of Streptococcus species, based on data from http://patricbrc.org
context_page_description: Streptococcus is a genus of gram-positive coccus or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales, in the phylum Firmicutes. Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains that may appear bent or twisted.
  The term was coined in 1877 by Viennese surgeon Albert Theodor Billroth, by combining the prefix "strepto-", together with the suffix "-coccus"
  Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes.
  In 1984, many bacteria formerly grouped in the genus Streptococcus were separated out into the genera Enterococcus and Lactococcus. Currently, over 50 species are recognised in this genus. This genus has been found to be part of the salivary microbiome.
context_section_description: Streptococci have been divided into six groups on the basis of their 16S rDNA sequences: S. anginosus, S. gallolyticus, S. mitis, S. mutans, S. pyogenes and S. salivarius. The 16S groups have been confirmed by whole genome sequencing (see figure). The important pathogens S. pneumoniae and S. pyogenes belong to the S. mitis and S. pyogenes groups, respectively, while the causative agent of dental caries, Streptococcus mutans, is basal to the Streptococcus group.
caption: Phylogenetic tree of Streptococcus species, based on data from PATRIC.[22] 16S groups are indicated by brackets and their key members are highlighted in red.
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