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': 'Mechanism of action of quinolones is: \nSelect and explain. \nA. Inhibits DNA gyrase, B. Inhibits bacterial protein synthesis, C. Inhibits bacterial cell wall synthesis, D. Inhibits intake of folic acid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mechanism of action of Fluoroquinolones\nThe FQs inhibit the enzyme bacterial DNA gyrase (primarily active in gram negative bacteria), which nicks double-stranded DNA, introduces negative supercoils and then reseals the nicked ends. This is necessary to prevent excessive positive supercoiling of the strands when they separate to permit replication or transcription.\nReference: Essentials of Medical Pharmacology Eighth Edition KD\xa0TRIPATHI page no 760', 'role': 'assistant'}]