What eye drops are recommended for treating bacterial conjunctivitis?

Topical Antibiotic Eye Drops for Bacterial Conjunctivitis

For mild to moderate bacterial conjunctivitis, use topical fluoroquinolones (moxifloxacin 0.5%, gatifloxacin 0.5%, or levofloxacin 1.5%) as first-line therapy, dosed 3 times daily for 7 days, with fourth-generation agents preferred for superior gram-positive coverage. 1, 2, 3

Treatment Algorithm by Severity

Mild Bacterial Conjunctivitis

• Topical broad-spectrum antibiotics shorten symptom duration and reduce transmissibility, with clinical remission rates 36% higher than placebo by days 2-5 (RR 1.36; 95% CI 1.15-1.61) 1
• First-line options include:
  • Moxifloxacin 0.5%: 1 drop 3 times daily for 7 days (FDA-approved dosing) 4
  • Gatifloxacin 0.5%: 1 drop 3 times daily for 7 days 3, 5
  • Levofloxacin 1.5%: superior microbiological eradication compared to older fluoroquinolones 2
• Alternative WHO-endorsed options: topical gentamicin, tetracycline, or ofloxacin 0.3% (though older generation with inferior gram-positive coverage) 1, 2

Moderate to Severe Bacterial Conjunctivitis

• Copious purulent discharge, pain, and marked inflammation require more aggressive therapy 1
• Obtain conjunctival cultures and Gram stain if gonococcal infection suspected 1
• Consider loading dose regimen: 1 drop every 5-15 minutes initially, then hourly applications, followed by standard 3-times-daily dosing 5
• For lesions near the limbus or severe presentations, add systemic antibiotics 1, 5

Critical Resistance Considerations

MRSA Conjunctivitis

• Fluoroquinolones are generally poorly effective against MRSA ocular isolates (42% of Staphylococcal isolates show methicillin resistance with concurrent fluoroquinolone resistance) 2, 3
• Use compounded topical vancomycin for suspected or confirmed MRSA 1, 2, 3

Fluoroquinolone Resistance Risk Factors

• Recent fluoroquinolone use 2, 3
• Recent hospitalization 2
• Recent ocular surgery 2, 3
• Geographic variation: Pseudomonas resistance to moxifloxacin increased from 19% to 52% in southern India (2007-2009) 2

Resistant Pseudomonas

• Consider topical colistin 0.19% for resistant Pseudomonas aeruginosa 2, 3

Special Pathogen-Specific Treatment

Gonococcal Conjunctivitis

• Systemic antibiotic therapy is mandatory (topical therapy alone is insufficient) 1, 3, 5
• Saline lavage promotes comfort and faster resolution 1
• Daily follow-up required until resolution 1
• Screen for concomitant sexually transmitted infections and treat sexual contacts 1

Chlamydial Conjunctivitis

• Systemic antibiotics required (topical therapy inadequate) 1, 3
• Moxifloxacin has activity against Chlamydia trachomatis but systemic therapy still needed 5

Neonatal Chlamydial Conjunctivitis

• Oral erythromycin achieves 96% clinical cure and 97% microbiological cure 1, 3
• Oral azithromycin (single dose) shows 60% cure rate; 3-day course achieves 86% cure 1

Fourth-Generation vs. Older Fluoroquinolones

Why Fourth-Generation Agents Are Preferred

• Moxifloxacin and gatifloxacin have superior gram-positive coverage compared to ciprofloxacin 0.3% and ofloxacin 0.3% 2, 3, 5
• Moxifloxacin achieves 81% complete resolution by 48 hours vs. 44% with polymyxin B/trimethoprim 6
• Microbiological success rate of 74.5% with twice-daily moxifloxacin formulation vs. 56% with vehicle 7
• Effective against principal pathogens: H. influenzae (98.5%), S. pneumoniae (86.4%), S. aureus (94.1%) 7

FDA-Approved Fluoroquinolone Options

• Moxifloxacin 0.5% 4
• Gatifloxacin 0.5% 3
• Levofloxacin 1.5% 2, 5
• Besifloxacin 0.6% 5
• Ciprofloxacin 0.3% (older generation) 5, 8
• Ofloxacin 0.3% (older generation) 2, 5

Monitoring and Follow-Up

When to Reassess

• If no improvement after 3-4 days, obtain culture and sensitivity testing 5
• If no improvement after 7 days, reevaluate diagnosis and treatment 2
• Each follow-up should include: interval history, visual acuity measurement, and slit-lamp biomicroscopy 1, 5

Treatment Failures

• Consider MRSA (switch to vancomycin) 2, 3
• Consider resistant Pseudomonas (switch to colistin 0.19%) 2, 3
• Reassess for viral, allergic, or other non-bacterial etiologies 1

Common Pitfalls and Caveats

• Do not use contact lenses during active bacterial conjunctivitis 1, 4
• Prolonged antibiotic use risks overgrowth of non-susceptible organisms including fungi 4
• Consider local resistance patterns when selecting therapy (resistance varies geographically) 5
• Topical antibiotics do not select for resistance at distal body sites (nose, throat) when used appropriately 9
• Most common adverse events: conjunctivitis, decreased visual acuity, dry eye, keratitis, ocular discomfort (1-6% incidence) 4