This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'All of the following statements about penicillin-binding proteins are true EXCEPT : \nSelect and explain. \nA. Present on cell surface, B. Mutation in PBPs gives rise to resistance, C. These are target site of vancomycin, D. These are targeted by imipenem', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Beta-lactam antibiotics act by inhibiting the cross-linking of peptidoglycan chains in the bacterial cell wall. This action is carried out by transpeptidase enzyme. Transpeptidases and similar enzymes involved in cross-linking are called penicillin-binding proteins (PBPs). All beta-lactam antibiotics bind to PBPs and inhibit cell wall synthesis. \nThe drugs in p-lactam category are:\n\nPenicillin\nCephalosporins\nCarbapenems e.g imipenem\nMonobactam e.g. aztreonam\nMutation in PBPs is an important cause of methicillin resistance in Staphylococcus aureus.\nVancomycin does not bind to PBPs but acts by inhibiting transglycosylase.', 'role': 'assistant'}]