Question

Which of the following statement(s) is(are) TRUE about fluoroquinolone drugs?

• A. They contain quinolone ring(s)
• B. They inhibit RNA polymerase
• C. They bind to bacterial topoisomerase
• D. They bind to 23S rRNA within the 50S ribosome subunit

Hint:

Fluoroquinolones are DNA synthesis inhibitors, not protein or RNA synthesis inhibitors.
Remember the distinction: Rifampicin targets RNA polymerase; macrolides target ribosomes; fluoroquinolones target topoisomerases.
The presence of a fluorine atom in their structure enhances antibacterial activity and pharmacokinetics.

Answer 1

The Correct Option is A, C

Step 1: Fluoroquinolones are synthetic broad-spectrum antibiotics that contain a quinolone ring structure. This is their defining chemical feature (so option A is correct).
Step 2: They act by inhibiting bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, which are enzymes crucial for DNA replication and transcription (so option C is correct).
Step 3: They do not inhibit RNA polymerase; this mechanism is characteristic of rifampicin, not fluoroquinolones (so option B is incorrect).
Step 4: They do not target ribosomes or rRNA. Binding to 23S rRNA of the 50S ribosomal subunit is the mechanism of macrolides (e.g., erythromycin), not fluoroquinolones (so option D is incorrect).
\(\therefore\) The correct statements are (A) and (C).