Methicillin resistant staphylococcus aureus is found on many individuals skin and usually causes no major problems. However if it gets inside the body, for instance under the skin or into the lungs, it can cause important infections such as boils or pneumonia. Individuals who carry this organism are usually totally healthy, have no problems whatever and are considered simply to be carriers of the organism. The term MRSA is used to describe those examples of this organism that are resistant to commonly used antibiotics. Methicillin was an antibiotic used many years ago to treat patients with Staphylococcus aureus infections. It is now no longer used except as a means of identifying this particular type of antibiotic resistance.