What eye drop antibiotic is recommended for adult conjunctivitis?

Topical Antibiotic Selection for Adult Bacterial Conjunctivitis

For adult bacterial conjunctivitis, topical gentamicin, tetracycline, or ofloxacin are recommended as first-line antibiotic eye drop treatments, with moxifloxacin being particularly effective for faster symptom resolution. 1

Diagnosis and Assessment

Before selecting an antibiotic, determine the likely cause of conjunctivitis:

• Bacterial conjunctivitis - characterized by mucopurulent discharge, mattering/adherence of eyelids upon waking, and absence of itching 2
• Viral conjunctivitis - typically presents with watery discharge, preauricular lymphadenopathy, and often a history of recent upper respiratory infection
• Allergic conjunctivitis - marked by itching, bilateral involvement, and seasonal patterns

Antibiotic Selection Algorithm

First-Line Options:

• Topical gentamicin - broad-spectrum coverage against gram-negative and some gram-positive organisms 3, 1
• Topical tetracycline - effective against many common pathogens including Chlamydia 3, 1
• Topical ofloxacin - fluoroquinolone with excellent broad-spectrum coverage 3, 1
• Topical moxifloxacin 0.5% - superior efficacy with faster resolution (81% resolution at 48 hours) and convenient dosing (three times daily) 1, 4

Special Considerations:

1. For severe bacterial conjunctivitis:

   • Moxifloxacin 0.5% ophthalmic solution three times daily for 5-7 days 4
   • Alternative: Besifloxacin 0.6% ophthalmic suspension three times daily for 5 days 5

2. For suspected gonococcal conjunctivitis:

   • Requires BOTH systemic and topical therapy
   • Systemic: Ceftriaxone (single dose)
   • PLUS topical antibiotic therapy 3, 1

3. For suspected chlamydial conjunctivitis:

   • Requires systemic therapy with:
     • Azithromycin (1g orally, single dose) OR
     • Doxycycline (100mg orally twice daily for 7 days) OR
     • Levofloxacin (500mg orally once daily for 7 days) 3

Treatment Duration and Administration

• Standard treatment course: 5-7 days 1
• Alternative shorter course: Moxifloxacin-AF (xanthan gum formulation) twice daily for 3 days 6
• Continue treatment until:
  • Resolution of discharge
  • No more mattering of eyelids in the morning
  • Reduction in conjunctival injection

Important Clinical Pearls

• Most bacterial conjunctivitis cases improve within 1-3 days of appropriate antibiotic therapy 1
• Topical antibiotics significantly accelerate recovery and reduce symptom duration 1
• Consider delayed antibiotic prescribing for mild cases, as this approach has shown similar symptom control to immediate prescribing 1
• Increasing resistance to fluoroquinolones has been reported, particularly in MRSA isolates (42% of Staphylococcal isolates showing methicillin resistance) 1

Red Flags Requiring Ophthalmology Referral

• Lack of response to therapy after 3-4 days
• Moderate to severe pain
• Decreased vision
• Corneal involvement
• Conjunctival scarring
• Recurrent episodes
• History of herpes simplex virus eye disease
• Immunocompromised patients 1

Prevention of Spread

• Patients can typically return to work or school after 24 hours of antibiotic treatment 1
• Advise frequent handwashing and avoiding sharing towels and pillowcases 1