The pneumococcus (Streptococcus pneumoniae)

Streptococcus pneumoniae is called the pneumococcus!

Strep­to­coc­cus pneu­mo­ni­ae, which is also called the pneu­mo­coc­cus, is a bac­teri­um that is com­mon­ly found in the upper res­pi­ra­to­ry tract of human beings. It can some­times infect the lung, result­ing in pneu­mo­nia. In cas­es of pneu­mo­nia, the air sacs in the lung fill with flu­id.

Drawing of how the air sacs in the lungs are affected by pneumonia or emphysema.
Pneu­mo­nia means that the air sacs of the lungs can­not fill with air.

The infec­tion can some­times spread through­out the body via the blood­stream (sep­sis). An infec­tion that reach­es the flu­id sur­round­ing the brain is called menin­gi­tis because it caus­es inflam­ma­tion of the meninges, which are the mem­branes that cov­er the brain. Bac­te­r­i­al menin­gi­tis is a seri­ous dis­ease.

The pneu­mo­coc­cus bac­teri­um is sur­round­ed by a cap­sule made out of com­pli­cat­ed sug­ars (poly­sac­cha­rides). Dif­fer­ent strains of pneu­mo­coc­cus have dif­fer­ent poly­sac­cha­rides in their cap­sule. The old­er vac­cines against pneu­mo­coc­ci were made out of these poly­sac­cha­rides. The new­er vac­cines are con­ju­gate vac­cines, which means that the poly­sac­cha­ride is bound to a bit of pro­tein. This pro­tein helps the immune sys­tem devel­op a stronger immune response to the pneu­mo­coc­cus. As this video explains, the use of the con­ju­gate vac­cine has decreased the num­ber of chil­dren with blood­stream or menin­gi­tis due to pneu­mo­coc­cal infec­tion.