What is the first‑line treatment for bacterial conjunctivitis in children and adults, and what antibiotic regimen should be used for patients who wear contact lenses?

First-Line Treatment for Bacterial Conjunctivitis

For uncomplicated bacterial conjunctivitis in both children and adults, topical fluoroquinolones (moxifloxacin, levofloxacin, gatifloxacin, ciprofloxacin, or besifloxacin) applied four times daily for 5-7 days are the first-line treatment, while contact lens wearers require fluoroquinolones specifically (ofloxacin or ciprofloxacin) due to the higher risk of Pseudomonas infection. 1, 2

Standard Treatment Algorithm for Non-Contact Lens Wearers

Children (>12 months) and Adults

• First-line therapy: Topical fluoroquinolone antibiotics four times daily for 5-7 days 1, 2

  • FDA-approved options for children >12 months include levofloxacin, moxifloxacin, gatifloxacin, ciprofloxacin, and besifloxacin 1
  • Fourth-generation fluoroquinolones (moxifloxacin 0.5%) provide superior gram-positive coverage, including activity against some MRSA strains 2
  • No single antibiotic has demonstrated superiority over others, allowing selection based on dosing convenience and cost 2

• Expected outcomes: 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 2, 3

• Alternative agents if fluoroquinolones are unavailable: gentamicin, tetracycline, or ofloxacin 0.3% four times daily for 5-7 days 2

Infants (<12 months)

• Standard regimen: Broad-spectrum topical antibiotic four times daily for 5-7 days 4
• Treatment reduces symptom duration from 7 days to 5 days and prevents secondary bacterial corneal ulceration 4

Contact Lens Wearers: Modified Approach

Contact lens wearers require fluoroquinolones specifically (ofloxacin or ciprofloxacin) because of the substantially higher risk of Pseudomonas aeruginosa infection, which demands more aggressive coverage. 2

• Use topical fluoroquinolones four times daily for 5-7 days 2
• Discontinue contact lens use during treatment 2
• The rationale is that Pseudomonas is a common pathogen in contact lens-related infections and requires fluoroquinolone coverage 2, 5

Special Circumstances Requiring Systemic Antibiotics

Gonococcal Conjunctivitis

• Systemic therapy is mandatory—topical antibiotics alone are insufficient 1, 2
• Adults: Ceftriaxone 250 mg IM single dose plus azithromycin 1 g oral single dose 2
• Children <18 years: Ceftriaxone 125 mg IM single dose 1
• Neonates: Ceftriaxone 25-50 mg/kg IV or IM single dose (maximum 125 mg) 1, 4
• Add topical antibiotics and saline lavage for comfort 2, 4
• Daily follow-up until complete resolution to prevent corneal perforation 1, 2
• Obtain conjunctival cultures and Gram stain before initiating treatment 1, 2
• Consider sexual abuse in all pediatric cases 1, 2

Chlamydial Conjunctivitis

• Systemic therapy is required because >50% of affected infants have concurrent infection at other sites (nasopharynx, genital tract, lungs) 1, 2
• Adults: Azithromycin 1 g oral single dose or doxycycline 100 mg oral twice daily for 7 days 2
• Children ≥8 years: Azithromycin 1 g oral single dose or doxycycline 100 mg oral twice daily for 7 days 1
• Children <8 years or <45 kg: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into 4 doses for 14 days 1, 4
• Neonates: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into 4 doses for 14 days 1, 4
• No evidence supports additional topical therapy beyond systemic treatment 1, 2
• Treatment efficacy is approximately 80%; a second 14-day course may be required 4
• Consider sexual abuse in all pediatric cases 1, 2

Red Flags Requiring Immediate Ophthalmology Referral

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

Follow-Up Strategy

• Instruct patients to return for evaluation in 3-4 days if no improvement is noted 1, 2
• If no improvement after 3-4 days, consider alternative diagnoses (viral, allergic) or resistant organisms (particularly MRSA) 1, 2
• For gonococcal conjunctivitis, daily visits until complete resolution are mandatory 1, 2
• For chlamydial conjunctivitis, re-evaluate after treatment completion due to potential 19% failure rate 2

Critical Pitfalls to Avoid

• Never use combination antibiotic-steroid drops (e.g., Tobradex) unless viral etiology—particularly HSV or adenovirus—has been definitively excluded, as steroids can exacerbate viral infections and prolong viral shedding 2
• Do not miss gonococcal or chlamydial infection, which require systemic therapy; delayed treatment can lead to corneal perforation within 24 hours 1, 4
• Avoid indiscriminate antibiotic use in viral conjunctivitis, as antibiotics provide no benefit and promote resistance 2
• Do not use oral antibiotics (e.g., Augmentin) for routine bacterial conjunctivitis, as they cannot achieve therapeutic levels in the conjunctiva and are reserved exclusively for gonococcal and chlamydial infections 2

Antimicrobial Resistance Considerations

• MRSA isolates show 42% fluoroquinolone resistance in some regions 2
• Pseudomonas aeruginosa resistance to moxifloxacin increased from 19% to 52% in some areas between 2007-2009 2
• If no response to fluoroquinolones within 48-72 hours, obtain conjunctival cultures and consider compounded topical vancomycin for suspected MRSA 1, 2
• MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides but remain susceptible to vancomycin 2

Natural History and When Treatment Can Be Deferred

• Mild bacterial conjunctivitis in immunocompetent adults is self-limited, with approximately 64% of cases resolving spontaneously by days 6-10 without treatment 2, 6
• However, topical antibiotics shorten symptom duration, enhance bacterial eradication, and reduce transmissibility 7, 3
• In resource-limited settings where antibiotics are unavailable, povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics 1, 2

Infection Control Measures

• Strict hand hygiene with soap and water is crucial to prevent transmission 1, 2
• Avoid sharing towels and close contact during the contagious period 1
• Children can generally return to school once treatment has been initiated for 24 hours and symptoms begin to improve 1