Two make a pair
The pneumococcus, also called Streptococcus pneumoniae, is a Gram1-positive organism, because it is stained by Gentian violet. It can be observed under the microscope generally by groups of 2 bacteria (so-called diplococci).
A protective armor
The pneumococcus has a capsule2 that protects it from the white blood cells (macrophages3 and neutrophils4). In the lung, the macrophages represent the first line of defense against invading microbes (pathogens). Thus, the pneumococcus thanks to its capsule may resist to the macrophages of the lung and represents the first cause of pneumonia.
Transmitted by droplets
Sensitive to antibiotics
Today, most pneumococci remain sensitive to penicillin and its derivatives. However, the excessive use of antibiotics, for example for viral infections for which the antibiotic is useless, may gradually lead to an increase in the rate of resistance of pneumococci to penicillin8 and its derivatives.