Which of the following is an example of a Quinolone?

Ciprofloxacin is classified as a Quinolone, which is a type of antibiotic known for its broad spectrum of activity against both Gram-negative and certain Gram-positive bacteria. Quinolones, including ciprofloxacin, work by inhibiting bacterial DNA gyrase and topoisomerase IV. This action disrupts the replication and transcription of bacterial DNA, effectively leading to the death of the bacteria.

In the context of the other antibiotics listed, amoxicillin belongs to the penicillin class and acts by inhibiting cell wall synthesis. Doxycycline is a member of the tetracycline class and works by inhibiting protein synthesis. Azithromycin is a macrolide antibiotic that also targets bacterial protein synthesis but in a different manner. Each of these antibiotics has a distinct mechanism of action and spectrum, which is why they are categorized differently from Quinolones like ciprofloxacin.