Staphylococcus aureus

Staphylococcus aureus (also "S. aureus", from the Greek σταφυλόκοκκος, “grape-cluster berry”, Latin aureus, “golden”) is a Gram-positive, round shaped bacterium appearing in grape-like clusters, often living on the skin or in the nose of a person, as well as in the lower reproductive tract of women. It is anaerobic, which means that it can grow without an oxygen atmosphere. Although "S. aureus" lives as a normal inhabitant on the human body, it can become an opportunistic pathogen. This means that if people have a weakened immune system, they can become ill from "S. aureus" infections. It causes a variety of illnesses, from skin and joint infections to respiratory infections, and food poisoning. Some of the diseases caused can be life threatening, like meningitis, bacteremia and toxic shock syndrome. "S. aureus" is a very common cause of infection in hospitals.
"S. aureus" infections can spread through skin-to-skin contact with an infected person, contact with objects touched by an infected person, and through contact with pus from an infected wound. As symptoms begins to show, the patient is contagious for 2 weeks, with the illness lasting overall a few weeks. If untreated, the infection can be deadly. To avoid "S. aureus" infections, hygiene measures such as daily showers or baths and frequent hand washing with soap are advised.
Some strains of "S. aureus" have become increasingly resistant to antibiotic treatment, for example methicillin-resistant "S. aureus" (MRSA). No vaccine for "S. aureus" has been developed.
"S. aureus" was discovered in 1880 by a Scottish surgeon, Alexander Ogston. He called it Staphylococcus because of its round, grape-like appearance under a microscope. In 1884, Friedrich Julius Rosenbach identified the Staphylococcus aureus strain from a related bacterium. Before 1940, infections with this pathogen were fatal. However, as penicillin was developed, doctors found that it could cure "S. aureus" infections. By the end of the decade, "S. aureus" became widely resistant to penicillin.
The evolution of "S. aureus" enabled it to be carried in human hosts without causing infections, allowing it to be widespread among the population. There are many health factors that affect this, which may include age, sex, diabetes and smoking, alongside genetic variations. Therefore, whether strains of "S. aureus" become invasive depends on human factors.