What do fluoroquinolones inhibit to exert their bactericidal effect?

Fluoroquinolones exert their bactericidal effect primarily by inhibiting two key enzymes involved in bacterial DNA replication: DNA gyrase and topoisomerase IV. DNA gyrase is crucial for introducing negative supercoils into DNA, which is necessary for the replication process. Topoisomerase IV is important for separating the intertwined daughter DNA strands following replication. By targeting these enzymes, fluoroquinolones effectively disrupt DNA replication and repair, leading to cell death in susceptible bacteria.

The action of fluoroquinolones is particularly effective because bacteria are highly reliant on these enzymes for maintaining the integrity and functionality of their genetic material. Without the proper functioning of DNA gyrase and topoisomerase IV, bacterial cells are unable to replicate their DNA or divide properly, which ultimately leads to their demise.

In contrast, RNA polymerase inhibition affects the transcription process of RNA from DNA, which is not the primary action of fluoroquinolones. Cell wall synthesis inhibitors target the structural integrity of bacterial cell walls, while ribosomal function interference affects protein synthesis. These processes are important, but they are not the mechanism by which fluoroquinolones achieve their bactericidal effect.