Definition of Pneumococcus (Streptococcus pneumoniae)

Pneumococcus (Streptococcus pneumoniae): Are Gram-positive bacteria in the shape of a slightly pointed cocci. They are usually found in pairs (diplococci), but are also found singly and in short chains.

Pneumococcus is the leading cause of bacterial pneumonia and otitis media (middle ear infections) and an important contributor to bacterial meningitis. Pneumococcal infections are the most common invasive bacterial infections in children in the United States, causing about 1,400 cases of meningitis, 17,000 cases of bloodstream infections, and 71,000 cases of pneumonia every year in children under 5.

Vaccines now exist for those individuals at high risk of infection with this bacterium. Pneumococcal disease is also a significant source of respiratory infections in adults particularly those with lung disease.

The formal name of the bacterium is now Streptococcus pneumoniae. (The "strepto-" means twisted and "-coccus" comes from the Greek kokkos meaning berry.) Because of its coming in pairs, it has also been called Diplodocus pneumoniae. "Pneumoniae" refers to its propensity to settle in the lungs and cause pneumonia.