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

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_Staphylococcus_aureus#mecA 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.