Methicillin-resistant staphylococci do not respond to β–lactam antibiotics because :
Resistance to most penicillins is due to elaboration of beta-lactamase.
Methicillin is most resistant penicillin to β-lactamase.
Staphylococcus aureus develops resistance to methicillin by the acquisition of altered penicillin-binding proteins.
They produce a β–lactamase which destroys methicillin and related drugs
They elaborate an amidase which destroys methicillin and related drugs
They have acquired penicillin binding protein which has low affinity for β-lactam antibiotics
They are less permeable to β-lactam antibiotics