What eye drops are recommended for a patient with erythemic conjunctiva, mild scleral injection, and purulent drainage, worse in one eye?

Treatment for Bacterial Conjunctivitis with Purulent Drainage

Start with a topical fluoroquinolone antibiotic eye drop (moxifloxacin 0.5% or gatifloxacin 0.3%) as monotherapy, avoiding combination steroid-antibiotic drops initially. 1

Initial Antibiotic Selection

The clinical presentation—erythemic conjunctiva, mild scleral injection, and purulent drainage worse in one eye—is consistent with bacterial conjunctivitis, most likely nongonococcal given the unilateral predominance and purulent (not hyperpurulent) discharge. 2

Recommended First-Line Options:

• Moxifloxacin 0.5%: Instill one drop in the affected eye 3 times daily for 7 days 3

  • Fourth-generation fluoroquinolone with excellent Gram-positive and Gram-negative coverage 4
  • Superior clinical success rates compared to trimethoprim/polymyxin B in pediatric patients 4
  • Well-tolerated with mostly mild ocular adverse events 4

• Gatifloxacin 0.3%: Day 1: one drop every 2 hours while awake (up to 8 times); Days 2-7: one drop 2-4 times daily 5

• Levofloxacin 0.5%: Demonstrated 89-90% microbial eradication rates, significantly superior to older fluoroquinolones 6

Alternative Options:

• Azithromycin 1.5%: One drop twice daily for 3 days only 7
  • Sustained tissue levels for 4 days in tears, 7 days in conjunctiva 7
  • 88% complete resolution rate in bacterial conjunctivitis 7
  • Convenient shorter treatment duration

Critical Management Principles

What NOT to Do Initially:

Do not use combination steroid-antibiotic drops (like Tobradex) as initial therapy. 1 The American Academy of Ophthalmology explicitly advises against this approach because:

• Corticosteroids should only be added after 2-3 days of antibiotic therapy 1
• The organism must be identified first 1
• The epithelial defect must be healing before adding steroids 1
• Fungal keratitis must be ruled out, as steroids worsen fungal infections 1

Monitoring and Follow-Up:

• Reassess within 48 hours: If no improvement, modify therapy and consider reculture 1
• Avoid subtherapeutic dosing: Do not taper antibiotics below therapeutic levels, as this increases antibiotic resistance 1
• Taper appropriately: Prolonged antibiotic use causes toxicity; taper as infection improves 1

Red Flags Requiring Urgent Ophthalmology Referral:

Watch for signs suggesting more serious bacterial infection (gonococcal or severe nongonococcal): 2

• Marked eyelid edema
• Marked purulent (hyperpurulent) discharge
• Preauricular lymphadenopathy
• Corneal infiltrate or ulcer (especially superiorly)—this can lead to perforation
• Rapid progression despite treatment

Common Pitfalls to Avoid:

• Don't assume viral etiology: While viral conjunctivitis is common, purulent discharge strongly suggests bacterial infection 2
• Don't use antibiotics for confirmed viral conjunctivitis: They are ineffective and promote resistance 8
• Don't ignore unilateral presentation: Bacterial conjunctivitis can be unilateral or bilateral; unilateral presentation doesn't rule it out 2
• Don't use chronic prophylactic antibiotics: This promotes resistant organisms 1

Expected Clinical Course:

Mild bacterial conjunctivitis is typically self-limited in adults, but treatment accelerates resolution and prevents complications (corneal infection, spread to others). 2 Most patients show significant improvement within 3-5 days of appropriate antibiotic therapy. 7, 6