What antibiotics are used to treat bacterial conjunctivitis (pink eye)?

Antibiotics for Bacterial Conjunctivitis (Pink Eye)

Fourth-generation fluoroquinolones like moxifloxacin 0.5% administered three times daily for 7 days are recommended as first-line treatment for bacterial conjunctivitis due to their superior efficacy and faster resolution of symptoms compared to other antibiotics. 1

First-Line Treatment Options

Fluoroquinolones

• Moxifloxacin 0.5% ophthalmic solution: Instill one drop in the affected eye 3 times a day for 7 days 2

  • Effective against common pathogens including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Haemophilus influenzae 2
  • Has better coverage of gram-positive pathogens than earlier generation fluoroquinolones 1
  • Clinical studies show moxifloxacin is superior to placebo and noninferior to other antibiotics like levofloxacin 3

• Ofloxacin: Endorsed by the WHO Essential Medicines List for conjunctivitis treatment 4, 1

Other Topical Options

• Gentamicin: Recommended by WHO Essential Medicines List 4
• Tetracycline: Recommended by WHO Essential Medicines List 4

Special Situations

Gonococcal Conjunctivitis

• Requires systemic antibiotics (ceftriaxone) in addition to topical therapy 1
• Conjunctival cultures and Gram staining should be obtained if gonococcal infection is suspected 1

Chlamydial Conjunctivitis

• Requires systemic antibiotics (azithromycin or doxycycline) 1
• For trachoma specifically, a single dose of oral azithromycin or topical azithromycin/tetracycline is recommended 4
• Azithromycin 1.5% ophthalmic solution for 3 days (twice daily) has shown efficacy in trachomatous conjunctivitis 5

Pediatric Patients

• Children should receive the same topical antibiotics as adults, with dosage adjustments for systemic therapy when needed 1
• Studies show azithromycin 1.5% ophthalmic solution is effective for bacterial conjunctivitis in children 6
• Fusidic acid viscous drops (twice daily) showed better compliance than tobramycin in children aged 2-9 years 7

Pregnant Women

• Should avoid doxycycline, quinolones, or tetracyclines
• Erythromycin or amoxicillin is recommended for chlamydial infection 1

Treatment Algorithm

1. For typical bacterial conjunctivitis:

   • Start with moxifloxacin 0.5% ophthalmic solution, 1 drop 3 times daily for 7 days

2. If fluoroquinolones are contraindicated:

   • Use gentamicin or tetracycline topical preparations

3. For suspected gonococcal conjunctivitis:

   • Obtain cultures
   • Administer systemic ceftriaxone plus topical antibiotics

4. For suspected chlamydial conjunctivitis:

   • Administer systemic azithromycin or doxycycline (erythromycin for pregnant women)

Prevention of Spread

• Patients can return to work or school after 24 hours of antibiotic treatment 1
• Practice good hygiene: frequent handwashing, avoid sharing towels and pillowcases, avoid touching eyes 1

When to Refer to Ophthalmology

Immediate referral is necessary for:

• Visual loss
• Moderate to severe pain
• Severe purulent discharge
• Corneal involvement
• Lack of response to therapy within 48-72 hours
• Recurrent episodes 1

Potential Pitfalls

• Overuse of antibiotics for viral conjunctivitis (which doesn't respond to antibiotics)
• Prolonged use of antibiotics may result in overgrowth of non-susceptible organisms 2
• Increasing prevalence of resistance to fluoroquinolones, particularly with methicillin-resistant S. aureus 1
• Patients should be advised not to wear contact lenses if they have signs or symptoms of bacterial conjunctivitis 2