This site might answer some of your questions:
CDC
Why does CDC think so many cases of MRSA are being recognized across the country?
MRSA has been recognized as a problem in the healthcare setting for over 20 years. CDC believes that MRSA has been emerging in the community over the
last several years. It is difficult to determine whether there is an increase in MRSA disease in the community or an increased awareness and
recognition of MRSA disease. However, it is clear that some of the recently recognized outbreaks of CA-MRSA are associated with strains that have some
unique properties compared to the traditional hospital-based MRSA strains, suggesting some biologic properties (like virulence factors) may allow the
CA-MRSA strains to spread more or cause more disease; however, these hypothesis need testing and confirmation.
