This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Antimetabolites and Quinolones, Subject name: Pharmacology
Mechanism of action of ciprofloxacin in gram negative bacteria:- 
Select and explain. 
A. Inhibition of mycolic acid, B. Inhibition of topoisomerase IV, C. Inhibition of DNA gyrase, D. Inhibition of helicase
C: Inhibition of DNA gyrase
Answer: C: Inhibition of DNA gyrase 
Explanation: MECHANISM OF FLUOROQUINOLONES (FQ) In gram negative bacteria, FQ inhibit DNA gyrase by binding to its A subunit and interfere with cutting and resealing function. In gram positive bacteria, FQ inhibit similar enzyme DNA topoisomerase IV.