What is the appropriate diagnosis and management for acute bacterial conjunctivitis, including first‑line topical antibiotics and hygiene measures?

Bacterial Conjunctivitis: Diagnosis and Management

Diagnosis

Bacterial conjunctivitis is diagnosed clinically by the presence of purulent discharge, mattering and adherence of eyelids on waking, lack of itching, and absence of a history of prior conjunctivitis. 1

Key diagnostic features include:

• Purulent or mucopurulent discharge (strongest predictor of bacterial etiology) 2, 1
• Eyelid matting upon awakening (highly specific for bacterial cause) 1
• Absence of itching (helps distinguish from allergic conjunctivitis) 1
• Unilateral or bilateral red eye with conjunctival injection 3
• No significant pain or visual loss (red flags requiring immediate ophthalmology referral) 4, 5

Cultures are NOT routinely needed for uncomplicated cases in primary care. 4 However, obtain conjunctival cultures and Gram staining before treatment if: 4, 5

• Gonococcal infection is suspected (hyperacute onset, severe purulent discharge)
• Moderate to severe disease with copious discharge
• Immunocompromised patients
• Contact lens wearers
• No improvement after 3-4 days of appropriate therapy

First-Line Treatment

For uncomplicated bacterial conjunctivitis, prescribe a 5-7 day course of broad-spectrum topical antibiotic applied four times daily, with topical fluoroquinolones (particularly moxifloxacin 0.5%) as the preferred first-line agent due to superior coverage of common pathogens including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. 4

Antibiotic Selection

No single antibiotic has demonstrated superiority for mild cases, so choose based on dosing convenience and cost. 3, 4 However:

• Fourth-generation fluoroquinolones (moxifloxacin 0.5%, gatifloxacin 0.5%) provide superior gram-positive coverage, including some MRSA strains 4, 5
• Alternative options if fluoroquinolones unavailable: gentamicin, tetracycline, or ofloxacin 0.3% 4
• Polymyxin B/trimethoprim is acceptable for mild cases 4
• Povidone-iodine 1.25% ophthalmic solution may be as effective as antibiotics when access is limited 4

Expected Outcomes

Topical antibiotics accelerate clinical and microbiological remission in days 2-5 of treatment, reduce transmissibility, and allow earlier return to school or work. 4, 6 Specifically:

• 62% clinical cure by days 3-5 with antibiotics vs. 28% with placebo 7
• 91% cure by days 8-10 with antibiotics vs. 72% with placebo 7
• Without treatment, 64% of cases resolve spontaneously by days 6-10 2, 6

Hygiene Measures and Infection Control

Counsel patients on strict hand hygiene with soap and water, avoiding eye rubbing, using separate towels and pillows, and avoiding close contact during the contagious period (typically 10-14 days for viral conjunctivitis). 3, 4, 5

Critical infection control measures: 3, 4, 5

• Wash hands frequently with soap and water
• Use separate towels and pillowcases from other household members
• Discard multiple-dose eyedrop containers after infection resolves to avoid reinfection
• Avoid close contact with others during active infection
• Children may return to school once discharge resolves (typically 24-48 hours after starting antibiotics)

Special Circumstances Requiring Different Management

Contact Lens Wearers

Reserve fluoroquinolones (ofloxacin or ciprofloxacin) for contact lens wearers due to higher risk of Pseudomonas infection. 4, 5 Discontinue contact lens use until infection completely resolves. 5

Gonococcal Conjunctivitis

Gonococcal conjunctivitis requires immediate systemic antibiotic therapy (ceftriaxone 1 g IM single dose plus azithromycin 1 g orally single dose for adults), not topical treatment alone. 4, 5 This is a vision-threatening emergency requiring: 4, 5

• Conjunctival cultures and Gram staining before treatment
• Daily monitoring until resolution
• Saline lavage for comfort
• Immediate ophthalmology referral

Chlamydial Conjunctivitis

Chlamydial conjunctivitis requires systemic antibiotics (azithromycin 1 g orally single dose or doxycycline 100 mg orally twice daily for 7 days), as topical therapy alone is insufficient. 4, 5 In infants, more than 50% have concurrent infection at other sites (nasopharynx, lungs). 4, 5

Suspected MRSA

MRSA conjunctivitis may require compounded topical vancomycin if unresponsive to fluoroquinolones within 48-72 hours, as MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides but susceptible to vancomycin. 4, 5

Follow-Up Strategy

Instruct patients to return for evaluation in 3-4 days if no improvement is observed. 4, 5 At follow-up, perform: 4, 5

• Interval history
• Visual acuity measurement
• Slit-lamp biomicroscopy

Signs of positive response include: 4

• Reduced pain and discharge
• Decreased eyelid edema or conjunctival injection
• Initial re-epithelialization

Red Flags Requiring Immediate Ophthalmology Referral

Refer immediately to an ophthalmologist if any of the following are present: 4, 5

• Visual loss or significant change in vision
• Moderate to severe pain (beyond mild irritation)
• Severe purulent discharge (suggests gonococcal infection)
• Corneal involvement (opacity, infiltrate, or ulcer)
• Conjunctival scarring
• Lack of response after 3-4 days of appropriate therapy
• Recurrent episodes
• History of HSV eye disease
• Immunocompromised state
• Neonatal conjunctivitis (requires systemic treatment)

Critical Pitfalls to Avoid

Indiscriminate use of topical antibiotics or corticosteroids should be avoided. 3 Specifically:

• Do NOT prescribe antibiotics for viral conjunctivitis, which accounts for unnecessary costs and promotes resistance 4
• Do NOT use topical corticosteroids without definitively excluding HSV, as steroids potentiate viral replication and worsen infection 3, 5
• Do NOT use combination antibiotic-steroid drops (e.g., Tobradex) in routine conjunctivitis without excluding viral etiology 4, 5
• Do NOT prescribe oral antibiotics for routine bacterial conjunctivitis; they are reserved exclusively for gonococcal and chlamydial infections 4
• Do NOT continue antibiotics beyond 7 days without specific indication, as prolonged use causes toxicity and promotes resistance 4
• Consider sexual abuse in pre-adolescent children with gonococcal or chlamydial conjunctivitis 4, 5