Which of the following is NOT a second-generation fluoroquinolone?

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

Answer: (C)

This question hinges on which drugs fall into which generation of fluoroquinolones. The second-generation drugs include ciprofloxacin, ofloxacin, and norfloxacin, which were developed to broaden Gram-negative coverage (with ciprofloxacin notably effective against Pseudomonas). Levofloxacin, on the other hand, is the pure S-enantiomer of ofloxacin and is classified as a third-generation fluoroquinolone, offering improved Gram-positive coverage (such as Streptococcus pneumoniae) while keeping good Gram-negative activity. So levofloxacin is not a second-generation fluoroquinolone.