Question

Quinolone antibiotics treat bacterial infections by blocking the activity of topoisomerase. Why does this treatment work? Explain what occurs at the molecular level.

a) Quinolones inhibit ribosome function, disrupting protein synthesis in bacteria.
b) Quinolones prevent bacterial cell wall synthesis by targeting peptidoglycan formation.
c) Quinolones interfere with bacterial DNA replication by blocking topoisomerase activity.
d) Quinolones disrupt bacterial cellular respiration by inhibiting ATP synthesis.

Answer 1

Quinolone antibiotics, such as fluoroquinolones, are effective because they inhibit topoisomerases which are crucial for bacterial DNA replication. This selective inhibition of bacterial enzymes allows for the targeted killing of bacterial cells, while minimizing harm to host cells, making them potent against a range of bacterial infections.

Step-by-step explanation:

Quinolone antibiotics treat bacterial infections by blocking the activity of topoisomerase. This treatment works because topoisomerases, like DNA gyrase (topoisomerase type II) and topoisomerase IV, are essential enzymes that facilitate the unwinding of DNA, which is a critical step in DNA replication. Quinolones, such as fluoroquinolones including ciprofloxacin and levofloxacin, bind to these enzymes and prevent the replication of bacterial DNA, ultimately leading to bacterial cell death. These antibiotics show selective toxicity as they target bacterial enzymes which differ structurally from those found in eukaryotic cells, minimizing harm to host organisms' cells.

Chemical modifications to the quinolone structure have led to the development of fluoroquinolones, which have a broader spectrum of activity against both Gram-positive and Gram-negative bacteria. However, these drugs can also lead to side effects due to their mechanism of action. Despite this, the inhibition of the bacterial DNA replication process makes them highly effective in the treatment of various infections.