What are the recommended first‑line treatments for presumed bacterial conjunctivitis, including options for contact‑lens wearers, children, and patients at risk for resistant organisms?

Treatment of Bacterial Conjunctivitis

For uncomplicated bacterial conjunctivitis, prescribe a topical fluoroquinolone (moxifloxacin 0.5% or ofloxacin 0.3%) three times daily for 5-7 days, as this provides superior coverage against the three principal pathogens (Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae) and accelerates clinical resolution. 1

First-Line Treatment Algorithm

Standard Cases (Non-Contact Lens Wearers)

• Topical moxifloxacin 0.5% is the preferred first-line agent, dosed three times daily for 5-7 days, offering superior gram-positive coverage including some MRSA strains 1, 2
• Alternative fluoroquinolones include ofloxacin 0.3% four times daily for 5-7 days if moxifloxacin is unavailable or cost-prohibitive 1
• No single antibiotic demonstrates superiority for mild cases, so selection can be based on dosing convenience and cost 1
• Topical antibiotics provide earlier clinical and microbiological remission (68% cure rate vs 55% with placebo by days 4-9), allowing faster return to work or school 1

Contact Lens Wearers

• Reserve fluoroquinolones (ofloxacin or ciprofloxacin) for contact lens wearers due to higher risk of Pseudomonas infection requiring more aggressive coverage 1
• Instruct patients to discontinue contact lens wear immediately until infection resolves 2

Alternative Options When Fluoroquinolones Unavailable

• Polymyxin B/trimethoprim one drop four times daily for 5-7 days is an effective alternative with proven efficacy in pediatric populations 3, 4
• Gentamicin, tetracycline, or ofloxacin 0.3% are WHO-endorsed alternatives 1
• Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics when antibiotic access is limited 1

Special Populations and Circumstances

Children

• Moxifloxacin 0.5% three times daily for 5-7 days improves adherence compared to more frequent dosing regimens 1
• Fluoroquinolones including moxifloxacin, levofloxacin, gatifloxacin, ciprofloxacin, and ofloxacin are FDA-approved for children older than 12 months 5, 2
• For children under 12 months, azithromycin 1% ophthalmic solution one drop twice daily for 2 days, then once daily for 5 days is an alternative 6

Severe Bacterial Conjunctivitis (Copious Purulent Discharge, Pain, Marked Inflammation)

• Obtain conjunctival cultures and Gram staining BEFORE initiating treatment if gonococcal infection is suspected 1, 7
• Start empiric fluoroquinolone therapy while awaiting culture results 7
• Consider loading dose regimen: one drop every 5-15 minutes for the first hour, then hourly until clinical improvement, then switch to three times daily 1
• Arrange daily follow-up until resolution if gonococcal infection confirmed 1

Gonococcal Conjunctivitis (Requires Systemic Therapy)

• Adults: Ceftriaxone 1 g IM single dose PLUS azithromycin 1 g orally single dose 1
• Neonates: Ceftriaxone 25-50 mg/kg IV or IM single dose (maximum 125 mg) 5
• Add saline lavage to promote comfort and faster resolution 1
• Daily ophthalmology monitoring is mandatory until complete resolution 1, 5
• Topical antibiotics alone are insufficient 1, 7

Chlamydial Conjunctivitis (Requires Systemic Therapy)

• Adults: Azithromycin 1 g orally single dose OR doxycycline 100 mg orally twice daily for 7 days 1
• Neonates: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into 4 doses for 14 days 5
• Children ≥8 years: Azithromycin 1 g orally single dose OR doxycycline 100 mg orally twice daily for 7 days 5
• Topical therapy alone is inadequate because >50% of infants have concurrent infection at other sites 1, 5
• Monitor for infantile hypertrophic pyloric stenosis in infants <6 weeks receiving erythromycin 5

Suspected MRSA Conjunctivitis

• If no improvement after 48-72 hours of fluoroquinolone therapy, obtain conjunctival cultures 1
• Compounded topical vancomycin may be required, as MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides but susceptible to vancomycin 1, 7
• MRSA prevalence is rising in nursing home residents and community-acquired cases, with 42% of staphylococcal isolates showing fluoroquinolone resistance 1

Critical Red Flags Requiring Immediate Ophthalmology Referral

• Visual loss or decreased visual acuity 1, 5
• Moderate to severe pain beyond mild irritation 1, 5
• Severe purulent discharge suggesting gonococcal infection 1, 5
• Corneal involvement (opacity, infiltrate, or ulcer) 1, 5
• Conjunctival scarring 1
• Lack of response after 3-4 days of appropriate therapy 1, 5
• History of HSV eye disease 1, 5
• Immunocompromised state 1, 5
• Neonatal conjunctivitis (requires systemic treatment coordinated with pediatrician) 5

Follow-Up Strategy

• Instruct patients to return in 3-4 days if no improvement is observed 1, 5
• At follow-up, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy 1
• Signs of positive response include reduced pain and discharge, decreased eyelid edema or conjunctival injection, and initial re-epithelialization 1
• For gonococcal conjunctivitis, daily visits are mandatory until complete resolution 1, 5
• For chlamydial conjunctivitis, re-evaluate after treatment completion due to potential 19% failure rate 1

Important Clinical Pitfalls

• Do NOT use combination antibiotic-steroid drops (e.g., tobramycin/dexamethasone) unless viral etiology—particularly HSV or adenovirus—has been definitively excluded, as steroids can exacerbate viral infections 1, 5
• Avoid topical corticosteroids in HSV conjunctivitis without antiviral coverage, as they potentiate viral replication and can cause corneal perforation 1, 5
• Do NOT prescribe oral antibiotics for routine bacterial conjunctivitis; they are reserved exclusively for gonococcal and chlamydial infections 1
• Consider sexual abuse in pre-adolescent children with gonococcal or chlamydial conjunctivitis and document diagnosis with standard culture 1, 5
• Screen for concurrent genital infections and treat sexual partners in cases of chlamydial and gonococcal conjunctivitis 1
• Mild bacterial conjunctivitis is self-limited, with 64% of cases resolving spontaneously by days 6-10 without treatment 1, 8

Infection Control Measures

• Strict hand hygiene with soap and water is critical to prevent transmission 1, 5, 9
• Avoid eye rubbing, use separate towels, and avoid close contact during the contagious period 1
• Discard multiple-dose eyedrop containers after infection resolves to avoid cross-contamination 5
• For viral conjunctivitis, avoid close contact for 7-14 days from symptom onset 5

Resistance Considerations

• Geographic resistance patterns show Pseudomonas aeruginosa resistance to moxifloxacin increased from 19% to 52% in some regions between 2007-2009 1
• Individual risk factors for fluoroquinolone resistance include recent fluoroquinolone use, hospitalization, advanced age, and recent ocular surgery 1, 7
• Reserve fluoroquinolones for moderate to severe cases to preserve their effectiveness 7, 10