What does streptococcus mean?
Streptococcus is a genus of spherical bacteria whose cells often arrange themselves in chains or clusters. The name combines Greek roots meaning “twisted” and “berry,” reflecting the bead-like appearance of many cells under a microscope. Members of the genus vary in their effects: some are harmless members of the human microbiome, while others cause illnesses including strep throat, pneumonia, and certain forms of meningitis. In clinical shorthand, “strep” may refer to Streptococcus infection or, in the expression strep throat, specifically to infection of the throat and tonsils. Accurate identification often matters because different species cause different diseases and may respond differently to antibiotics. The term is both a formal taxonomic genus name and a common name for individual bacteria belonging to that genus.
nounA spherical bacterium that commonly occurs in chains or clusters. The term is also used collectively for members of the bacterial genus Streptococcus, which includes species that can cause diseases such as strep throat and pneumonia.
- Any bacterium of the genus Streptococcus, especially one that occurs in chains or clusters.
- A member of the genus Streptococcus in formal biological classification.
"Doctors identified the infection as caused by group A Streptococcus."
"The laboratory culture showed growth of Streptococcus."
"Streptococcus pneumoniae is a leading cause of community-acquired pneumonia."
The standard plural is streptococci, pronounced with a long final “i” sound. Streptococcus may also be used unchanged as a mass term when discussing the genus collectively.
"Several streptococci were visible in the bacterial culture."
Streptococcus takes its name from the chains its cells often form, like a necklace of tiny spheres.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does streptococcus come from?
The word was formed in the late nineteenth century from Greek streptos, meaning “twisted” or “curved,” and kokkos, meaning “berry.” The combination referred to the chain-like arrangement of the bacteria. Streptococcal is the corresponding adjective, while streptomycin names an antibiotic whose name was also derived from the same Greek root.
Related word forms
How streptococcus is actually used
In general medical and scientific usage, the name is commonly capitalized when referring to the genus, as in Streptococcus pneumoniae. In phrases such as strep throat, the abbreviated form “strep” is informal.