Coccus

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Image:Arrangement of cocci bacteria.svg Image:Staphylococcus aureus Gram.jpg

Cocci (singular - coccus, from the Latin coccinus (scarlet) and derived from the Greek kokkos (berry) ) are any bacteria whose overall shape is spherical or nearly spherical.<ref name=Brock>Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0131443291.</ref>

Aggregations of coccoid bacteria often occur and these forms have specific names as well<ref name=Baron>Salton MRJ, Kim KS (1996). Structure. In: Baron's Medical Microbiology (Baron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.</ref>; listed here are the basic forms as well as representative bacterial genera:

pairs, or diplococci (Enterococcus)
groups of four or eight known as tetrads or sarcina (Sarcina)
bead-like chains, or streptococci (Streptococcus)
grapelike clusters, or staphylococci (Staphylococcus)

Important human pathogens caused by coccoid bacteria include staphylococci infections, some types of food poisoning, some urinary tract infections, toxic shock syndrome, gonorrhea, as well as some forms of meningitis, throat infections, pneumonias, and sinusitis.<ref name=Sherris>Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0838585299.</ref>