Tobramycin Eyedrops for Bacterial Conjunctivitis
Dosage Regimen
For mild to moderate bacterial conjunctivitis, instill 1-2 drops of tobramycin 0.3% into the affected eye(s) every 4 hours (approximately 4-6 times daily) for 5-7 days. 1, 2
For severe infections, instill 2 drops hourly until improvement is observed, then reduce frequency before discontinuation. 1
Treatment Duration
- A 5-7 day course is recommended as it accelerates clinical and microbiological remission by days 2-5, reduces transmissibility, and allows earlier return to school or work. 2
- Most patients should demonstrate reduced discharge, pain, and lid edema within 24-48 hours of initiating therapy. 3
- Do not taper below 3-4 times daily before completing the full course, as subtherapeutic dosing increases antibiotic resistance risk. 4, 3
Clinical Monitoring and Follow-Up
- Patients should return for follow-up if no improvement occurs after 3-4 days of treatment. 2, 3
- At follow-up visits, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy. 2
- If no improvement by 48 hours, consider switching to a fluoroquinolone or obtaining conjunctival cultures. 3
Important Caveats and Pitfalls
When Tobramycin is Insufficient
- Gonococcal conjunctivitis requires systemic antibiotic therapy (ceftriaxone) in addition to topical treatment—tobramycin alone is inadequate. 2, 3
- Chlamydial conjunctivitis requires systemic antibiotics (azithromycin or doxycycline)—topical therapy alone is insufficient. 2, 3
- Contact lens wearers at higher risk for Pseudomonas infection should receive fluoroquinolones rather than tobramycin as first-line therapy. 2, 3
Resistance Concerns
- Bacterial resistance is a growing concern, particularly with MRSA infections, which may require compounded topical vancomycin rather than tobramycin. 2
- In neonatal intensive care settings, gram-negative conjunctivitis is often resistant to aminoglycosides like tobramycin. 2
- Poor adherence to frequent administration regimens contributes to treatment failure. 2
Medication Toxicity
- Prolonged use beyond 10 days can cause medication toxicity and corneal epithelial damage, so taper as the infection improves. 4, 3
- Medication toxicity can cause worsening inflammation or even corneal melting, which may be confused with antibiotic failure. 4
When to Refer to an Ophthalmologist
Refer patients with any of the following: 2
- Visual loss
- Moderate or severe pain
- Severe purulent discharge
- Corneal involvement
- Conjunctival scarring
- Lack of response to therapy after 3-4 days
- Recurrent episodes
Alternative Considerations
While tobramycin 0.3% four times daily for 7 days is effective, azithromycin 1.5% twice daily for 3 days demonstrates equivalent efficacy with superior convenience and compliance, particularly in children. 5, 6 Enhanced viscosity tobramycin formulations allow twice-daily dosing with equivalent efficacy to standard four-times-daily regimens. 7