Which antibiotic is most effective against Pseudomonas keratitis in a contact lens wearer?

• A. Ciprofloxacin
• B. Amoxicillin
• C. Erythromycin
• D. Azithromycin

Answer: (A)

When tackling Pseudomonas keratitis in a contact lens wearer, the crucial factor is selecting an antibiotic with strong activity against Pseudomonas aeruginosa and good ocular penetration for topical use. Ciprofloxacin fits that need perfectly because it is a fluoroquinolone with potent anti-pseudomonal activity and excellent corneal penetration when applied as eye drops, enabling rapid bacterial kill and control of infection. Amoxicillin generally does not reliably cover Pseudomonas and is not effective for this ocular pathogen. Erythromycin and azithromycin are macrolides with limited activity against Pseudomonas and are not suitable for treating this keratitis. So the choice with proven efficacy against Pseudomonas in the eye is ciprofloxacin, making it the best option for this scenario.