What is the next best step for a 20-month-old patient with conjunctivitis that is refractory to tobramycin (antibiotic) drops?

Management of Tobramycin-Refractory Conjunctivitis in a 20-Month-Old

Switch to erythromycin ophthalmic ointment (approximately 1 cm in length applied to the affected eye up to 6 times daily for 5-7 days), as this is the first-line alternative for bacterial conjunctivitis in young children when initial therapy fails. 1

Immediate Assessment Required

Before changing antibiotics, evaluate for these critical features that would require urgent ophthalmology referral:

• Visual changes or decreased vision - requires immediate ophthalmology consultation 2
• Moderate to severe pain - suggests possible corneal involvement or more serious infection 2
• Corneal involvement on examination - indicates keratitis requiring specialist management 2
• Severe purulent discharge - may indicate hypervirulent organism like gonococcus 2
• Immunocompromised state - changes management approach entirely 2

Determine the Likely Etiology

At 20 months, failure to respond to tobramycin after 3-4 days suggests either:

Viral Conjunctivitis (Most Common)

• Watery discharge with follicular reaction on inferior tarsal conjunctiva 2
• Preauricular lymphadenopathy often present 2
• Sequential bilateral involvement - starts unilateral then spreads 2
• Concurrent upper respiratory infection 2
• If viral: discontinue all antibiotics immediately - they provide no benefit and cause unnecessary toxicity 2, 3

Bacterial Conjunctivitis with Resistant Organism

• Mucopurulent discharge with matted eyelids in morning 2, 4
• Papillary rather than follicular reaction 2
• May have concurrent otitis media or sinusitis 2

Allergic Conjunctivitis

• Bilateral itching as predominant symptom 2
• Watery discharge without matting 2
• History of atopy, asthma, or eczema 2

Antibiotic Selection for Confirmed Bacterial Conjunctivitis

Erythromycin ointment is the appropriate choice for this age group because:

• FDA-approved for infants and young children 1
• Fluoroquinolones (moxifloxacin, gatifloxacin) are NOT FDA-approved for children under 12 months and should be avoided in very young children 1, 3, 5
• Tobramycin resistance is increasingly common, particularly with Staphylococcus aureus strains 6
• No single antibiotic has proven superiority for bacterial conjunctivitis, so choose the safest option for age 2

Dosing Regimen

• Apply approximately 1 cm ribbon of erythromycin ointment to affected eye(s) up to 6 times daily for 5-7 days 1
• Clinical improvement should be evident within 3-4 days 1
• If no improvement by day 3-4, reculture and refer to ophthalmology 2

Special Pathogen Considerations

If Gonococcal Infection Suspected

• Marked eyelid edema, severe purulent discharge, preauricular lymphadenopathy 2
• Topical therapy alone is insufficient - requires systemic ceftriaxone 25-50 mg/kg IV/IM single dose PLUS topical antibiotics 1
• Can cause corneal perforation - this is a medical emergency 2

If Chlamydial Infection Suspected

• Chronic course, persistent despite topical therapy 2
• Requires systemic erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into 4 doses for 14 days 1
• Topical therapy alone is inadequate 2

Infection Control Measures

• Emphasize frequent handwashing to parents and caregivers 1
• Avoid sharing towels, washcloths, or pillows 1
• Child can return to daycare 24 hours after starting treatment once symptoms begin improving 1
• For viral conjunctivitis, contagious period is 10-14 days from onset 2

Follow-Up Timeline

• Re-evaluate in 3-4 days if symptoms persist or worsen 1, 4
• Consider reculture if no improvement with second antibiotic 7
• Discontinue antibiotics for 12-24 hours before reculture to increase yield 7

Critical Pitfalls to Avoid

• Do not use fluoroquinolones in children under 12 months - not FDA-approved and erythromycin is safer 1
• Do not assume all conjunctivitis is bacterial - viral is extremely common and antibiotics cause harm without benefit 2, 3
• Do not miss gonococcal conjunctivitis - requires immediate systemic treatment to prevent corneal perforation 2, 1
• Do not use topical corticosteroids without ophthalmology supervision - can worsen HSV infections and cause elevated intraocular pressure 2, 8