Methicillin resistant staphylococci do not respond to b-lactam antibiotics because:: (A) 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
Answer is C. (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.