It is often carried by healthy individuals without symptoms. In a mild case, MRSA affects the skin, but it can become invasive and potentially deadly when it penetrates the body usually through a break in the skin, like a cut, scrape, or wound. It infects more than 90,000 Americans a year (http://www.cnn.com/2007/HEALTH/conditions/10/16/mrsa.cdc.ap/index.html?iref=n...), and due to a resistance to antibiotics, MRSA has become hard to treat by the medical community.
It is generally accepted that MRSA has become immune to many antibiotics due to the overuse. Bacteria are smart and very good at survival. They share knowledge about antibiotics, and can even acquire the necessary encoding for resistance by scavenging the remnants of dead bacteria killed by the antibiotic (http://health.howstuffworks.com/question561.html).
Alternative treatments for bacterial infections are widely available, but they have not been publicized in the recent media frenzy.