What do fluoroquinolones primarily inhibit in bacterial cells?

Fluoroquinolones are a class of antibiotics that primarily target bacterial DNA replication by inhibiting two critical enzymes: DNA gyrase and topoisomerase IV. DNA gyrase introduces negative supercoils into DNA, which is important for alleviating torsional strain during DNA replication and transcription. Topoisomerase IV helps in the decatenation of intertwined DNA strands after replication. Inhibiting these enzymes leads to the disruption of bacterial DNA synthesis, ultimately resulting in bacterial cell death.

The action of fluoroquinolones on DNA gyrase and topoisomerase IV is particularly effective against a wide range of gram-negative and gram-positive bacteria, making them valuable in treating various bacterial infections. Their mechanism of action is distinct from that of dihydrofolate reductase, which is targeted by other classes of antibiotics, or penicillin-binding proteins, which are affected by β-lactams. Similarly, HMG-CoA reductase is an enzyme involved in cholesterol synthesis and is the target of statins, not antibiotics. This specificity in action demonstrates the unique role of fluoroquinolones in the pharmacological arsenal against bacterial infections.