Library · Microorganism
Streptococcus pneumoniae
Make it clearer
Streptococcus pneumoniae, better known as pneumococcus, is a gram-positive bacterium, meaning it stains purple with the Gram stain, and it is a facultative anaerobe, meaning it can live with or without oxygen. Under the microscope it is lancet-shaped and typically shows up in pairs or in short chains.
The odd part is that it lives in healthy people. It colonizes the nasopharynx, the upper part of the throat behind the nose. And roughly 40% to 50% of healthy children and 20% to 30% of healthy adults are carriers. Infection develops when those bacteria are inhaled and travel down to the lower airway, deep inside the lung.
That is where the capsule comes in, a coating of polysaccharides, or chains of sugars, that surrounds the wall of the bacterium. The capsule is a slippery coat: the phagocyte finds nothing to grab. Granulocytes, the white blood cells that eat microbes, do not reach the wall, and that helps the bacterium escape phagocytosis.
In brief
Streptococcus pneumoniae is gram-positive, facultatively anaerobic and lancet-shaped, typically in pairs or short chains.
It colonizes the nasopharynx, and roughly 40% to 50% of healthy children and 20% to 30% of healthy adults are carriers; when those bacteria are inhaled they infect the lower airway.
Its polysaccharide capsule surrounds the cell wall and keeps granulocytes from reaching it, which helps the bacterium escape phagocytosis.
The capsule is a slippery coat: the phagocyte finds nothing to grab.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingStreptococcus pneumoniae, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated