A person with a staph infection has an infection that is caused by the bacteria, Staphylococcus aureus. Staph is normally present on the surface of the skin, and usually causes skin infections. However, Staph can infect the lungs, skin, bone, and other organs in the body.

A methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by bacteria that are resistant to powerful forms of penicillin. MRSA infections require treatment with a small group of very powerful antibiotics.

Like conventional staph, MRSA may be found normally on the skin and nasal passages. This infection is more common in hospital workers and in those who require care in a hospital for a long time.

Over the past 15 years, there have been increasing numbers of MRSA infections in the community. Most of those who have MRSA on their skin are not sick, but the bacteria can cause a serious infection if they enter the body through a wound in the skin. In the community, MRSA infections are usually skin infections. The infection may begin as an infected pimple or boil.

The increasing number of MRSA infections has made it difficult to treat staph infections of the skin, lungs, heart valves, bones, and joints.