Which antibiotic is listed as first-line for dacryocystitis in a patient without penicillin allergy?

• A. Cephalexin 500 mg qid
• B. Amoxicillin
• C. Doxycycline
• D. Azithromycin

Answer: (A)

Treat dacryocystitis with an antibiotic that reliably covers the organisms most commonly causing infection and is convenient for outpatient use. Cephalexin, a first-generation cephalosporin, fits this well because it provides solid coverage of Staphylococcus aureus and Streptococcus species, which are typical culprits in lacrimal sac infections, and it has good oral bioavailability for outpatient therapy. Dosing at 500 mg four times daily offers effective tissue levels to address the infection.

Amoxicillin alone is less reliable in this setting due to beta-lactamase–producing bacteria that reduce its effectiveness; using amoxicillin-clavulanate would broaden coverage but isn’t the chosen option here. Doxycycline and azithromycin have less consistent activity against the common Staph/Strep pathogens seen in acute dacryocystitis and are not considered first-line choices for this condition.