MRSA is methycillin resistand STAPHOLOCOCCUS aureus, the evil cousin of streptococcus (which is what this woman had).
I agree the reporter was shooting for interest and exploiting the controversy about home birth. I'm guessing she was infected with strep A during the birth, but it's possible she could have contracted it through any break in the skin/mucous membrane any time after. The woman on DHC contracted it via a tiny cut on her little finger. We injure ourselves like this all the time.
I've read (sorry, no remembered sources

) that it takes a particular mix of a persons immune system response to a certain bacteria, that you and I would shrug off, to cause such a terrible calamity as this woman had. Perhaps the way the immune system is suppressed during pregnancy?
When I worked at Harborview in Seattle, they flew in a 17 year old boy who was cut on a tractor blade in Montana while working on the family farm. He too developed necrotizing fasciitis and all of his limbs were amputated to save his life. He did not survive this. I have a little farm and open cuts from fencing or wranging with bird claws and beaks

and get inoculated with soil in them every day. If this organism caused EVERYONE to develop NF I'd have been dead years ago, and so would most of humanity.
You don't even have to be up to your armpits in filth (like I am every day at home AND at work

) to get this infection. It hits like lightening strikes from what literature I have read over the years.