<prompt> Mechanism of action of quinolones is:Inhibits DNA gyraseInhibits bacterial protein synthesisInhibits bacterial cell wall synthesisInhibits intake of folic acid  <response>: Mechanism of action of FluoroquinolonesThe 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.Reference: Essentials of Medical Pharmacology Eighth Edition KD TRIPATHI page no 760 