Acute purulent conjunctival infection — most often self-limited; topical antibiotics shorten course.
Also known as: bacterial conjunctivitis, pink eye bacterial, mucopurulent conjunctivitis, hyperacute conjunctivitis
Overview
Acute infection of the conjunctiva characterized by mucopurulent discharge, conjunctival hyperemia, and crusted/'stuck shut' eyelids. Distinguished from viral and allergic conjunctivitis by the character of discharge and clinical context.
Epidemiology
Most common in children; ~50-75% of pediatric conjunctivitis is bacterial. Adults more often viral. Hyperacute (gonococcal) and chlamydial conjunctivitis affect sexually active adults and neonates of infected mothers.
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Question 1EENTMedium
A 9-year-old girl presents with two days of bilateral eye redness and copious yellow-green discharge that mats her eyelashes together each morning. She denies pain, photophobia, or vision changes. On examination, both conjunctivae are diffusely injected with mucopurulent discharge at the lid margins. Visual acuity is 20/20 bilaterally, and the cornea is clear with no fluorescein uptake. She wears no contact lenses. Which of the following is the most appropriate treatment?
ATopical acyclovir ointment
BTopical ketotifen drops
CTopical erythromycin ointment
DOral amoxicillin-clavulanate
Reveal answer & full explanation
Correct answer: C — Topical erythromycin ointment
ATopical acyclovir ointment
BTopical ketotifen drops
CTopical erythromycin ointment✓
DOral amoxicillin-clavulanate
Why Topical erythromycin ointment is correct
This presentation is acute bacterial conjunctivitis: bilateral mucopurulent discharge with matted lashes and no corneal involvement.
Most common pathogens in children are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
First-line management for uncomplicated, non-contact-lens-wearer bacterial conjunctivitis is a topical antibiotic such as erythromycin ointment or polymyxin-trimethoprim drops, which shortens duration and reduces transmission.
Topical erythromycin provides broad gram-positive and limited gram-negative coverage appropriate for this presentation.
Why the others are wrong
D) Oral amoxicillin-clavulanate — reserved for suspected H. influenzae conjunctivitis-otitis syndrome or gonococcal/chlamydial disease, not routine cases.
A) Topical acyclovir ointment — treats herpes simplex keratitis, which presents with unilateral pain, photophobia, and dendritic corneal staining.
B) Topical ketotifen drops — a mast-cell stabilizer/antihistamine used for allergic conjunctivitis, which features itching and watery discharge rather than purulent exudate.
A 22-year-old woman presents with a 2-day history of a red, painful left eye with copious green discharge and a gritty sensation. She wears soft contact lenses, frequently sleeps in them, and replaces them less often than recommended. On examination, there is diffuse conjunctival injection and mucopurulent discharge; slit-lamp examination is pending to exclude corneal involvement. The clinician is concerned about Pseudomonas aeruginosa as the causative organism. Which of the following is the strongest risk factor for this patient's condition?
AOvernight soft contact lens use
BAttendance in a crowded daycare
CContact with infected secretions
DRecent upper respiratory illness
Reveal answer & full explanation
Correct answer: A — Overnight soft contact lens use
AOvernight soft contact lens use✓
BAttendance in a crowded daycare
CContact with infected secretions
DRecent upper respiratory illness
Why Overnight soft contact lens use is correct
Soft contact lens wear, particularly overnight/extended wear with poor hygiene and infrequent replacement, is the dominant risk factor for Pseudomonas aeruginosa conjunctivitis and the associated sight-threatening keratitis.
Pseudomonas thrives in the moist, hypoxic environment under a lens worn overnight and on contaminated lenses and cases, giving this patient the highest relative risk.
Why the others are wrong
Recent upper respiratory illness is a genuine risk factor, but it points to the otitis-conjunctivitis syndrome from nontypeable Haemophilus influenzae in children, not Pseudomonas in a contact lens wearer.
Attendance in a crowded daycare increases bacterial conjunctivitis transmission overall, yet it is a weaker, pediatric-skewed exposure that does not raise Pseudomonas risk.
Contact with infected secretions is a common transmission route for bacterial conjunctivitis, but it is a far weaker predictor of Pseudomonas than overnight contact lens wear in this patient.
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Contact lens wear (Pseudomonas, especially with poor hygiene or extended wear)
Recent upper respiratory infection (otitis-conjunctivitis syndrome — H. influenzae)
Crowded settings (schools, daycare)
Neonates born to mothers with untreated chlamydia or gonorrhea
Sexual transmission (gonococcal, chlamydial)
Immunocompromise
Pathophysiology
Bacterial inoculation of the conjunctival surface triggers a neutrophilic response, producing the characteristic purulent discharge. Common organisms in adults: Staphylococcus aureus, Streptococcus pneumoniae; in children: H. influenzae (often non-typeable), S. pneumoniae, M. catarrhalis. Pseudomonas aeruginosa in contact lens wearers. Neisseria gonorrhoeae produces hyperacute infection that can perforate the cornea within 24-48 h. Chlamydia trachomatis causes neonatal inclusion conjunctivitis and chronic adult inclusion conjunctivitis.
Clinical presentation
Symptoms
Eye redness, often beginning unilateral and spreading to fellow eye in 1-2 days
Mucopurulent (yellow/green) discharge throughout the day
Eyelids matted/stuck shut on awakening
Foreign body or 'gritty' sensation
Minimal or no itching (helps differentiate from allergic)
Mild discomfort; significant pain, photophobia, or vision loss suggests another diagnosis
Signs / physical exam
Diffuse bulbar and palpebral conjunctival injection
Purulent discharge — copious in hyperacute (gonococcal)
Lid edema and crusting
Cornea clear; visual acuity preserved
No preauricular lymphadenopathy (unlike viral or gonococcal)
Severe chemosis and lid edema in hyperacute gonococcal infection
Classic findings
Bilateral mucopurulent discharge with eyelids matted shut on awakening and normal vision in a school-age child.
Differential diagnosis
Viral conjunctivitis — Watery discharge, preauricular lymphadenopathy, recent URI; often bilateral after starting unilateral; supportive care
Hyperacute (gonococcal) conjunctivitis — Copious purulent discharge accumulating within minutes of wiping, severe lid edema, preauricular adenopathy; vision-threatening — Gram stain and culture, IM ceftriaxone PLUS topical therapy
Neonatal conjunctivitis (ophthalmia neonatorum) — Day of onset clues: chemical (day 0-1), gonococcal (2-5), chlamydial (5-14), HSV (1-2 weeks); gonococcal needs IV ceftriaxone — do not miss
Acute angle-closure glaucoma — Severe pain, vomiting, halos around lights, mid-dilated fixed pupil, hazy cornea, IOP >40; emergency
Subconjunctival hemorrhage — Painless flat red blood under conjunctiva; no discharge or visual change; self-resolves
Diagnostic workup
Labs
Most cases: clinical diagnosis; no testing needed
Gram stain and culture if: hyperacute presentation, contact lens wearer, severe disease, neonate, immunocompromised, treatment failure
NAAT for Chlamydia trachomatis and Neisseria gonorrhoeae in adults with suspected STI conjunctivitis or in neonatal conjunctivitis
Imaging
Slit-lamp examination if any pain, photophobia, decreased vision, contact lens wear, or treatment failure — exclude keratitis or iritis
Fluorescein staining if corneal involvement suspected
Diagnostic algorithm
Feature
Bacterial
Viral
Allergic
Discharge
Mucopurulent (yellow-green)
Watery
Stringy/mucoid, watery
Itching
Minimal
Mild
Hallmark (severe)
Laterality
Often bilateral
Often starts unilateral
Bilateral
Preauricular node
Absent (present in gonococcal)
Present
Absent
URI features
Sometimes
Often
No
Atopic history
—
—
Yes
First-line treatment
Topical antibiotic
Supportive (cool compress)
Antihistamine/MCS drops
Bedside differentiation of bacterial, viral, and allergic conjunctivitis.
Treatment
First-line
Most uncomplicated bacterial conjunctivitis is self-limited; topical antibiotics shorten course and reduce transmission
Topical ocular antibiotic — erythromycin ophthalmic ointment 0.5%, polymyxin B/trimethoprim drops, or moxifloxacin/ofloxacin drops × 5-7 days
Avoid topical aminoglycosides (gentamicin, tobramycin) as first line — corneal toxicity and limited gram-positive coverage
Frequent warm compresses to remove crusts; hand hygiene and dedicated towels to reduce spread
Contact lens wearers: discontinue lenses, use a topical fluoroquinolone (ciprofloxacin or moxifloxacin) for pseudomonal coverage, refer if any corneal involvement
Discard contaminated cosmetics and replace lenses/case after resolution
Second-line / adjunct
Hyperacute (gonococcal) conjunctivitis: ceftriaxone 1 g IM × 1 (or 25-50 mg/kg up to 125 mg IM/IV for neonates) PLUS saline irrigation PLUS topical erythromycin or ciprofloxacin; treat presumptively for chlamydia co-infection (azithromycin 1 g PO or doxycycline 100 mg BID × 7 days); ophthalmology referral
Adult chlamydial conjunctivitis: azithromycin 1 g PO × 1 OR doxycycline 100 mg PO BID × 7 days plus partner treatment
Neonatal chlamydial conjunctivitis: oral erythromycin × 14 days (topical does not eradicate nasopharyngeal carriage); monitor for pyloric stenosis
Neonatal gonococcal conjunctivitis: IV/IM ceftriaxone (single dose 25-50 mg/kg, max 125 mg) plus saline irrigation; admit
Same-day ophthalmology referral for any contact lens wearer with corneal involvement, suspected gonococcal infection, no improvement at 48 h, or vision-threatening signs
Complications
Corneal ulceration and perforation (hyperacute gonococcal or Pseudomonas in contact lens wearer)
Keratitis with permanent vision loss
Conjunctival scarring (chronic chlamydial — trachoma; leading global cause of preventable blindness)
Spread to fellow eye and close contacts
Pneumonia in neonates with chlamydial conjunctivitis (~10-20%)
PANCE pearls
Discharge type is a clinical clue (imperfect): purulent → bacterial; watery → viral; stringy/mucoid + itching → allergic.
Hyperacute purulent conjunctivitis = gonococcal until proven otherwise — sight-threatening; treat systemically with ceftriaxone and refer to ophthalmology.
All contact lens wearers with bacterial conjunctivitis require fluoroquinolone coverage for Pseudomonas and prompt ophthalmology evaluation.
Otitis-conjunctivitis syndrome in a child suggests H. influenzae — systemic amox-clav covers both.
References
AAO 2018 — American Academy of Ophthalmology. Conjunctivitis Preferred Practice Pattern. Ophthalmology 2019;126(1):P94-P169
CDC STI 2021 — Centers for Disease Control and Prevention. Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep 2021;70(4):1-187
AAP Red Book 2024 — American Academy of Pediatrics. Chlamydia trachomatis / Neisseria gonorrhoeae infections. In: Red Book 2024
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