Which of the following is a fourth generation fluoroquinolone?

• A. Besifloxacin
• B. Levofloxacin
• C. Ciprofloxacin
• D. Ofloxacin

Answer: (A)

Fourth-generation fluoroquinolones are defined by broader coverage, especially against Gram-positive cocci and anaerobes, and by improved activity against respiratory pathogens compared with earlier generations. Besifloxacin fits this newer class, and it’s notable as a topical ophthalmic agent with the expanded spectrum characteristic of the fourth generation. The other options belong to earlier generations: levofloxacin is a third-generation agent with strong Gram-negative and some Gram-positive/atypical activity, while ciprofloxacin and ofloxacin are second-generation drugs with potent Gram-negative coverage but less emphasis on Gram-positive and anaerobic activity. In short, besifloxacin’s spectrum and its place in the generation scheme make it the fourth-generation fluoroquinolone among these choices.