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Staphylococcus aureus

Golden yellow

Staphylococci are Gram positive cocci that appear purple on the Gram stain. One particular type of the staphylococcus, Staphylococcus aureus, is particularly dangerous. It is very often recognizable by a yellowish pigmentation which earned it its name (aureus meaning golden in Latin). In addition, compared to all other staphylococci, it presents 2 virulence factors which are also used in laboratories to differentiate it from other species: coagulase and protein A.

About 20 to 30% of healthy people are carriers of Staphylococcus aureus, most often in the nasal area but also sometimes in other areas of the skin (armpits, inguinal folds, for example). Staphylococcus epidermidis is very frequently present on the skin, as its name suggests.


Staphylococcus aureus is a bacterium that will cause abscesses following the multiplication of bacteria. These abscesses can be found in different organs or regions of the body. One of the particularly serious diseases is infection with Staphylococcus aureus of the valves of the heart (endocarditis).

The entry into the body of this agent, which is naturally present on some of our mucous membranes and sometimes on the skin, can occur, for example, when one is injured at a metal barrier. Then, the skin, which served as a protective structure, is permeable to the entry of staphylococcus aureus which could locally cause an abscess or even a more extensive infection. Particularly severe endocarditis1 can be seen, for example, when an addict will inject drugs by intravenous route without having previously and properly disinfected the skin.

Toxins that cause diarrhea

Certain strains of Staphylococcus aureus can cause toxigenic diseases, that is, due to toxins2. These toxigenic strains are, for example, agents of food poisoning3 which will occur a few hours after taking the food and disappear relatively quickly in less than 12 to 24 hours. These food poisonings should also be distinguished from gastroenteritis4 caused by viruses (norovirus, enterovirus, etc.) or bacteria (Salmonella, Campylobacter, etc.).