Diplococcus

Streptococcus pneumoniaean example of a diplocus.

In bacteriology: diplococci are a group of bacteria characterized by being cocci that typically have the shape of two joined cells. Examples of gram-negative diplococci are the genera Neisseria and Moraxella. Examples of gram-positive diplococci are the genera Streptococcus and Enterococcus. Many of these bacteria are naturally pathogenic. Presumably, diplococci have been linked to encephalitis lethargica.