methicillin-resistant Staphylococcus aureus (MRSA)

What is MRSA?

MRSA is a bacterial staphylococcus infection of the flesh that is resistant to several drugs and antibiotics. There are several various clones of MRSA and there is emerging resistance to all classes of antibiotics. The evolutionary history is not well understood.


Diagnosing MRSA is similar to diagnosing other skin infections such as staphylococcus. Typically, the doctor will look for classic signs of infection: redness, swelling, hot to the touch, fever, chills, abscesses, and drainage. After assessing the area, they will take a swab of the abscess to culture it and determine the pathogen that is infecting the area. If they believe it could be MRSA, they will prescribe antibiotics that should kill it, but they will test the culture for sensitivity to various drugs.

Frequency of Infection

Disease Course and Complications

Disease Course

MRSA is can be contracted at hospitals or in the community. Once it penetrates your bodies defenses, it will, typically, begin to form an abscess beneath the skin, but may only be superficial. Eventually, it will create a boil and may rupture. It causes swelling, redness, and pain. If left untreated, it will spread and begin to kill tissue and may enter the blood stream. If it gets into your bloodstream, it is now a systemic infection and will result in septic shock and death if medical treatment is not sought out in a timely manner. In some cases it becomes too deep and the limb or area may have to be amputated.


The groups that are most at risk for this infection are athletes, hospitalized individuals, and others that have been at a medical facility.


Published online before print May 21, 2002, doi: 10.1073/pnas.122108599
PNAS May 28, 2002 vol. 99 no. 11 7687-7692