A

David

Darling

coccus

Gram positive cocci

Gram positive cocci.


Coccus is a bacterium with a rounded or spherical shape. Cocci may be true spheres (e.g., staphylococci), helmet-shaped (e.g., pneumococci), or kidney-shaped (e.g., Neisseriae). They may occur alone, in pairs, or in groups. If found in pairs they are called diplococci, threes are a triad, etc. Other group types include: tetracoccus (groups of four), streptococcus (chains), sarcina (cubes of eight), and staphylococcus (irregular clusters). Diseases caused by cocci include pneumonia, tonsillitis, bacterial heart disease, meningitis, sepsis, and various skin diseases.