The bacterium Streptococcus pneumoniae is a tiny little one-celled organism found in most humans. For the most part, it’s not harmful to the human carrier, but sometimes (in susceptible individuals) it becomes pathogenic – a bad bacterium – and may be the cause of pneumonia, meningitis, bronchitis and sepsis, just to name a few.

It’s a well-studied bacterium, so one may think that it should be easy to overcome, but the bad bacterium is rather clever. It is able to change its surface, and therefore it may avoid our immune system, that is, if it does so in the “right” way. In many countries, including Denmark, the UK, and the USA, vaccine programs have been implemented. 

There are 90 serotypes of this bacterium - there are 90 different surface-variations of it. In 2001, researchers from the The Institute for Genomic Research (TIGR) in Maryland reported the first complete genome of a pneumococcal stain - since then known as the TIGR4 stain. The genome was published in Science Magazine (Science 20 July 2001: Vol. 293 no. 5529 pp. 498-506), and the in the news commentary Dan Faber wrote:

At the height of his power, Genghis Khan and his armies swept from the steppes of Mongolia, capturing two-thirds of the known world. But for sheer ferocity, Khan's forces pale next to those of a tiny microbe called Streptococcus pneumoniae. These pathogenic bacteria readily move from the throat to invade the lungs, blood, or brain—every year killing millions of children and elderly people worldwide with pneumonia, bloodstream infections, or meningitis. Now, researchers have uncovered clues to just what makes the organism so savage.

Eventhough researcher are on the right track to fight this bacterium, much still remains unkown. We'd be very happy if this visual review will increase public awareness of the bacterium.