In a patient with a sulfa drug allergy, which antibiotic is recommended for an ocular infection?

• A. Amoxicillin
• B. Clindamycin
• C. Erythromycin
• D. Gentamicin

Answer: (B)

When choosing an antibiotic for an ocular infection in a patient with a sulfa allergy, you want something that isn’t a sulfonamide and that covers the common eye pathogens, including MRSA. Clindamycin fits these needs because it’s a lincosamide with good activity against gram-positive cocci, including MRSA, and there are ocular formulations available. It avoids the sulfonamide class entirely, so it’s safe in someone with a sulfa allergy.

Amoxicillin is a penicillin and can be effective for many eye infections, but it doesn’t reliably cover MRSA. Erythromycin can treat many conjunctival infections but has limited MRSA activity. Gentamicin is strong against gram-negative bacteria and some staphylococci but offers less reliable MRSA coverage and is often used topically, with a different spectrum focus. Thus, clindamycin provides the best balance of MRSA coverage and non-sulfonamide safety for a sulfa-allergic patient with an ocular infection.