Quinolones and fluoroquinolones act against which bacterial target?

• A. DNA gyrase (topoisomerase II)
• B. Peptidoglycan synthesis
• C. Ribosomal 30S subunit
• D. RNA polymerase

Answer: (A)

Verified step by step guidance

1. Understand that quinolones and fluoroquinolones are classes of antibiotics that interfere with bacterial DNA replication.
2. Recall that DNA replication requires enzymes that manage DNA supercoiling and strand separation, such as DNA gyrase (topoisomerase II) and topoisomerase IV.
3. Recognize that quinolones specifically inhibit DNA gyrase, an enzyme critical for relieving torsional strain during DNA replication in bacteria.
4. Note that other options like peptidoglycan synthesis, ribosomal 30S subunit, and RNA polymerase are targets of different antibiotic classes (e.g., beta-lactams, aminoglycosides, and rifampin respectively).
5. Conclude that the bacterial target of quinolones and fluoroquinolones is DNA gyrase (topoisomerase II), which disrupts DNA replication and leads to bacterial cell death.