[timr]

MRSA is due to the mecA gene, which is integrated into the S. Aureus genome. It's not plasmid-mediated resistance, which means that it's less likely to disappear from bacterial populations, even in the absence of selective pressure:

http://www.eurekaselect.com/68849/article

[hga]

More than mecA, which itself doesn't sound like it's grossly maladaptive in the absence of β-Lactam antibiotics (it codes for an "replacement" enzyme that's not β-Lactam sensitive): https://en.wikipedia.org/wiki/Methicillin-resistant_Staphylo...

There's also regulatory genes that may be present, there are 6 known varieties of the whole gene cassette, with 5 further subtypes based on these regulators, so in the absence of β-Lactam antibiotics it sounds like a lot of them will be fit.

Nasty.

[Fomite]

True - but the post I was responding to wasn't talking about plasmid-mediated resistance, but rather a broad assertion that a competitive disadvantage will take care of things. That's a strong assumption for which we have a counter example.