Unfortunately, the US is not immune to MRSA. In fact, in a US hospital this past summer, vancomycin resistance emerged in staph. Which means if that particular strain also picks up resistance to the methicillin family, we are back to the 1940's as far as infection protocols go after surgery.
No, cockiness and arrogance is what led to the US CDC declaring only 30 years ago that the age of communicable diseases was finished.
How foolish we were. You want to see statistics - take a look at the Tuberculosis cases in the United States that are resistant to virtually every class of antibiotics available.
This is a global war alright. And the microbes are winning. We've won exactly one game in this battle, that being smallpox.
Political correctness is part of the problem here in the US, too. We may not have socialized medicine, but we have public health authorities who protect the right of AIDs victims to spread their disease, and the right of TB carriers to misuse antibiotics and make themselves into walking incubators of mutated strains.
Maybe it would have happened anyway, but big-city left-wing politics has certainly contributed.