What antibiotics are recommended for treating uncomplicated bacterial conjunctivitis, including first‑line topical agents and alternatives for patients with sulfa allergy, contact‑lens wearers, recent ocular trauma, or suspected resistant organisms?

Antibiotics for Bacterial Conjunctivitis

For uncomplicated bacterial conjunctivitis, prescribe a 5-7 day course of topical moxifloxacin 0.5% three times daily, which provides superior gram-positive coverage including some MRSA strains and achieves 81% complete resolution at 48 hours. 1

First-Line Topical Antibiotics

Standard Therapy for Uncomplicated Cases

• Topical fluoroquinolones are the preferred first-line agents, with no single antibiotic demonstrating superiority over others, allowing choice based on convenience and cost 2, 1
• Fourth-generation fluoroquinolones (moxifloxacin 0.5%, gatifloxacin, besifloxacin) offer superior gram-positive coverage compared to earlier generations, including activity against some methicillin-resistant S. aureus 1, 3
• Alternative broad-spectrum options include gentamicin, tetracycline, or ofloxacin 0.3% four times daily for 5-7 days if fluoroquinolones are unavailable 1, 3
• Polymyxin B/trimethoprim and erythromycin remain viable alternatives, though the World Health Organization specifically endorses gentamicin, tetracycline, and ofloxacin 3

Dosing Regimen

• Apply topical antibiotics four times daily for 5-7 days 2, 1, 3
• This regimen provides earlier clinical and microbiological remission (68.2% cure rate vs 55.5% with placebo by days 4-9) and allows faster return to work or school 1

Special Populations and Circumstances

Contact Lens Wearers

• Reserve fluoroquinolones (ofloxacin or ciprofloxacin) for contact lens wearers due to higher risk of Pseudomonas infection 3
• These patients require more aggressive coverage given the risk of rapidly progressive keratitis 3

Patients with Sulfa Allergy

• Avoid trimethoprim-containing combinations (polymyxin B/trimethoprim) 3
• Use fluoroquinolones, aminoglycosides (gentamicin, tobramycin), or macrolides (erythromycin) as alternatives 1, 3

Recent Ocular Trauma or Surgery

• Obtain conjunctival cultures and Gram staining before initiating treatment 2, 1
• Consider compounded fortified antibiotics if severe infection or resistant organisms are suspected 2

Suspected MRSA

• MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides but susceptible to vancomycin 1, 3
• If unresponsive to moxifloxacin within 48-72 hours, consider compounded topical vancomycin 1, 3
• MRSA has been isolated with increasing frequency from nursing home residents and community-acquired infections 2

Neonatal Intensive Care Setting

• Gram-negative conjunctivitis in low birth weight or low gestational age infants is often resistant to gentamicin 2, 3
• Microbiology laboratory testing should guide therapy, which may include compounded topical antibiotics such as vancomycin 2

Systemic Antibiotics Required

Gonococcal Conjunctivitis

• Systemic antibiotic therapy is mandatory for gonococcal conjunctivitis; topical therapy alone is insufficient 2, 1, 3
• Adults: Ceftriaxone 250 mg IM single dose plus azithromycin 1 g oral single dose 1, 3
• Neonates: Ceftriaxone 25-50 mg/kg IV or IM single dose 1
• Add saline lavage for comfort and more rapid resolution of inflammation 2
• Daily monitoring is required until resolution to prevent complications including corneal perforation 2, 1
• Obtain conjunctival cultures and Gram staining before initiating treatment 2, 1

Chlamydial Conjunctivitis

• Systemic therapy is indicated because more than 50% of infants may have infection at other sites (nasopharynx, genital tract, lungs) 2, 1
• Adults: Azithromycin 1 g oral single dose or doxycycline 100 mg oral twice daily for 7 days 1
• Neonates: Erythromycin base or ethylsuccinate 50 mg/kg/day oral divided into 4 doses for 14 days 1, 3
• Children ≥45 kg but <8 years: Azithromycin 1 g oral single dose 1
• Children ≥8 years: Azithromycin 1 g oral single dose or doxycycline 100 mg oral twice daily for 7 days 1
• No data support the use of topical therapy in addition to systemic therapy 2
• Re-evaluate following treatment as incidence of treatment failure can be as high as 19% 2
• Sexual contacts should be treated simultaneously, and patients should be retested approximately 3 months after treatment 1

Alternative When Antibiotics Unavailable

• Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotic therapy for treating bacterial conjunctivitis 2, 3
• Consider this option when access to antibiotics is limited, such as in low- to middle-income countries 2

Critical Red Flags Requiring Immediate Ophthalmology Referral

• Visual loss or significant change in vision 1
• Moderate to severe eye pain (beyond mild irritation) 1
• Severe purulent discharge suggesting possible gonococcal infection 2, 1
• Corneal involvement (opacity, infiltrate, or ulcer) 2, 1
• Conjunctival scarring 2, 1
• History of herpes simplex virus eye disease 1
• Immunocompromised state 2, 1
• Lack of response after 3-4 days of appropriate therapy 2, 1, 3
• Recurrent episodes 1

Common Pitfalls and How to Avoid Them

Avoid Indiscriminate Antibiotic Use

• Mild bacterial conjunctivitis is self-limited and typically resolves spontaneously in immune-competent adults without treatment 2, 4
• Viral conjunctivitis accounts for unnecessary antibiotic costs and promotes resistance 3
• Natural resolution occurs in 64% of cases by days 6-10 without treatment 1

Never Use Topical Corticosteroids Without Ruling Out HSV

• Topical corticosteroids are absolutely contraindicated in HSV conjunctivitis as they potentiate viral replication and worsen infection 1, 3
• Exclude HSV before considering any steroid use by looking for watery discharge, follicular reaction, and preauricular lymphadenopathy 1

Consider Sexual Abuse in Children

• Sexual abuse must be considered in preadolescent children with gonococcal or chlamydial conjunctivitis 2, 1
• Diagnosis should be documented by standard culture 1

Monitor for Infantile Hypertrophic Pyloric Stenosis

• Oral erythromycin is associated with risk of infantile hypertrophic pyloric stenosis in infants <6 weeks 1
• Monitor for signs and symptoms of this condition 1

Prevent Antibiotic Resistance

• Do not taper tobramycin below 3-4 times daily, as subtherapeutic doses increase resistance risk 3
• Repeat treatment intermittently using different medications with different mechanisms of action 3

Follow-Up Strategy

• Advise patients to return in 3-4 days if no improvement noted 2, 1, 3
• At follow-up, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy 2, 1, 3
• For gonococcal conjunctivitis, daily visits are required until resolution 2, 1
• For chlamydial conjunctivitis, re-evaluate after treatment completion due to 19% treatment failure rate 2

Infection Control Measures

• Strict hand hygiene with soap and water is crucial to prevent transmission 1, 3
• Avoid close contact for 7-14 days from symptom onset in viral conjunctivitis 1
• Discard multiple-dose eyedrop containers to avoid cross-contamination 1
• Avoid sharing towels, pillowcases, and makeup 5