What inexpensive eye drop is appropriate for treating acute bacterial conjunctivitis?

Inexpensive Eye Drop for Pink Eye

For uncomplicated bacterial conjunctivitis, use polymyxin B/trimethoprim eye drops four times daily for 5-7 days—this is the most cost-effective first-line option with proven efficacy comparable to expensive fluoroquinolones. 1, 2

Why Polymyxin B/Trimethoprim Is the Best Inexpensive Choice

• The American Academy of Ophthalmology explicitly states that for mild bacterial conjunctivitis, clinicians should choose the most convenient or least expensive antibiotic, as no clinical evidence suggests superiority of any particular agent. 1

• Polymyxin B/trimethoprim achieves clinical cure rates of 95-96% by day 7-10, which is statistically non-inferior to moxifloxacin (a much more expensive fluoroquinolone), according to a 2013 randomized controlled trial. 2

• This combination is FDA-approved for acute bacterial conjunctivitis caused by the most common pathogens: Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa. 3

• In pediatric studies, 95% of infected eyes were cured or improved within 7 days using polymyxin B/trimethoprim, with physicians rating overall efficacy as excellent or good in 96% of cases. 4

Dosing and Administration

• Apply 1 drop four times daily for 7 days to the affected eye(s). 4, 2

• Eye drops provide better corneal penetration than ointments, making them the preferred formulation for primary therapy. 5

• Ointment formulations can be used as adjunctive therapy or at bedtime in less severe cases, but should not replace drops as primary treatment. 5

When Polymyxin B/Trimethoprim Is NOT Appropriate

• Contact lens wearers require fluoroquinolones (ofloxacin or ciprofloxacin) due to higher risk of Pseudomonas infection that needs more aggressive coverage. 1

• Gonococcal conjunctivitis (severe purulent discharge, rapid onset, marked inflammation) requires systemic ceftriaxone plus azithromycin—topical antibiotics alone are insufficient. 1, 6

• Chlamydial conjunctivitis requires systemic antibiotics (azithromycin or doxycycline)—topical therapy alone will fail. 1, 6

• Suspected MRSA (nursing home residents, recurrent infections, failure to respond to initial therapy) may require compounded topical vancomycin, as MRSA is resistant to polymyxin B/trimethoprim. 1, 6

Alternative Inexpensive Options

• Gentamicin, tetracycline, or ofloxacin 0.3% are endorsed by the World Health Organization as acceptable alternatives if polymyxin B/trimethoprim is unavailable. 1

• Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics and can be considered when access to antibiotics is limited. 1

Critical Red Flags Requiring Immediate Ophthalmology Referral

Do NOT prescribe any topical antibiotic and arrange urgent ophthalmology evaluation if:

• Visual loss or significant change in vision occurs. 1, 6
• Moderate to severe eye pain (beyond mild irritation) is present. 1, 6
• Corneal involvement (opacity, infiltrate, or ulcer) is evident. 1, 6
• Severe purulent discharge suggests gonococcal infection. 1, 6
• History of herpes simplex virus eye disease exists. 6
• Patient is immunocompromised. 1, 6
• No improvement after 3-4 days of appropriate therapy. 1, 6, 5

Follow-Up Strategy

• Instruct patients to return in 3-4 days if no improvement is noted, at which point perform visual acuity measurement and slit-lamp examination. 1, 5

• Signs of positive response include reduced pain and discharge, decreased eyelid edema or conjunctival injection, and resolution of purulent discharge. 1

• If infection worsens or fails to improve after 48-72 hours, obtain conjunctival cultures and consider resistant organisms. 1, 5

Important Infection Control Measures

• Counsel patients on strict hand hygiene with soap and water, avoiding eye rubbing, using separate towels, and avoiding close contact during the contagious period. 1, 6

• Topical antibiotics reduce transmissibility and allow earlier return to school or work compared to no treatment. 1, 6

Cost-Effectiveness Evidence

• Using polymyxin B/trimethoprim for conjunctivitis would result in significant cost savings compared with fluoroquinolones, with no difference in clinical cure rates for typical community-acquired bacterial conjunctivitis. 2

• The 2013 randomized trial demonstrated that polymyxin B/trimethoprim achieves 72% clinical cure by day 4-6 and 96% by day 7-10, which is non-inferior to moxifloxacin. 2