BoardVitals Microbiology Practice Test

Fluoroquinolones combat bacterial infections primarily by inhibiting DNA replication. They achieve this through the targeting of bacterial topoisomerases, specifically topoisomerase II (DNA gyrase) and topoisomerase IV. These enzymes play essential roles in managing DNA supercoiling and the separation of DNA strands during replication and transcription. When fluoroquinolones bind to these enzymes, they prevent the necessary cuts and re-ligation of DNA strands, ultimately leading to DNA damage, which hinders the bacteria's ability to replicate and repair its DNA.

This targeted interference with DNA processes makes fluoroquinolones effective against a broad range of Gram-negative and some Gram-positive bacteria. Their unique mechanism of action distinguishes them from other antibiotic classes that either inhibit protein synthesis or cell wall synthesis, or that affect cell membrane permeability, which do not target DNA replication specifically.