This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
[{'content': 'Methicillin resistant staphylococci do not respond to b-lactam antibiotics because: \nSelect and explain. \nA. They produce a b-lactamase which destroys methicillin and related drugs, B. They elaborate an amidase which destroys methicillin and related drugs, C. They have acquired penicillin binding protein which has low affinity for b-lactam antibiotics, D. They are less permeable to b-lactam antibiotics', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (Ref: KDT 6/e p700) Resistance to most penicillins is due to elaboration of beta-lactamase. Methicillin is most resistant penicilling to b-lactamase. Staphylococcus aureus develops resistance to methicillins by acquisition of altered pencillin binding proteins.', 'role': 'assistant'}]