Ophthalmology · Infectious Conjunctivitis
The facts most likely to be tested
Bacterial conjunctivitis is characterized by purulent discharge and eyelid matting that typically recurs after wiping.
Staphylococcus aureus is the most common cause of bacterial conjunctivitis in adults, while Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are more common in children.
Hyperacute bacterial conjunctivitis, characterized by copious, thick, purulent discharge, is most commonly caused by Neisseria gonorrhoeae and requires systemic antibiotics.
Contact lens wearers with bacterial conjunctivitis are at high risk for Pseudomonas aeruginosa infection and require fluoroquinolone coverage.
The diagnosis of bacterial conjunctivitis is clinical, based on the presence of mucopurulent discharge and the absence of preauricular lymphadenopathy or follicular conjunctival reaction.
First-line treatment for non-gonococcal bacterial conjunctivitis is topical antibiotic drops such as trimethoprim-polymyxin B or erythromycin ointment.
Neisseria gonorrhoeae conjunctivitis is an ophthalmologic emergency that requires topical irrigation and intramuscular ceftriaxone to prevent corneal perforation.
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A 6-year-old boy is brought to the clinic by his mother due to a 2-day history of eye irritation. The mother reports that the child wakes up with his eyelids matted shut by a thick, yellow-green discharge. Physical examination reveals diffuse conjunctival injection and purulent exudate in the inferior fornix of the right eye. There is no evidence of preauricular lymphadenopathy or vesicular rash. The cornea is clear, and visual acuity is intact.
What is the most appropriate initial management for this patient?
Topical trimethoprim-polymyxin B or erythromycin ointment.
The patient presents with classic signs of bacterial conjunctivitis (purulent discharge and eyelid matting), which is treated empirically with topical antibiotics as per the first-line management guidelines.
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Etiology / Epidemiology
Common in children via direct contact; primary pathogens include S. pneumoniae, S. aureus, and H. influenzae.
Clinical Manifestations
Presents with purulent discharge and matting of the eyelids; vision remains unaffected.
Diagnosis
Primarily a clinical diagnosis; cultures are reserved for refractory cases or suspected N. gonorrhoeae.
Treatment
Trimethoprim-polymyxin B drops are first-line; contact lens wearers require coverage for Pseudomonas.
Prognosis
Self-limiting in 1-2 weeks; topical antibiotics shorten duration and reduce transmission.
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Epidemiology & Etiology
Highly contagious condition most prevalent in daycare settings and schools. Common bacterial pathogens include Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenzae. In sexually active adults, Neisseria gonorrhoeae must be considered if hyperacute, copious discharge is present.
Pertinent Anatomy
The conjunctiva is a thin, vascularized mucous membrane covering the sclera and inner eyelids. Inflammation leads to hyperemia and edema, which manifests as the classic injected appearance of the eye.
Pathophysiology
Direct inoculation of the conjunctival sac triggers an inflammatory cascade. Neutrophil infiltration results in the production of purulent exudate. The absence of corneal involvement preserves visual acuity, distinguishing it from more severe ocular pathologies.
Clinical Manifestations
Patients report purulent discharge and matting of the eyelids, especially upon awakening. Unlike viral or allergic etiologies, bacterial conjunctivitis is often bilateral but may start unilaterally. Red flags include decreased visual acuity, ciliary flush, or severe photophobia, which suggest corneal involvement or keratitis.
Diagnosis
Diagnosis is clinical based on history and physical exam. Gram stain and culture are the gold standard only if hyperacute onset or failure of initial therapy occurs. A positive culture for N. gonorrhoeae requires systemic treatment to prevent corneal perforation.
Treatment
Trimethoprim-polymyxin B is the first-line choice for most patients. Contact lens wearers must be treated with fluoroquinolones (e.g., ofloxacin) to cover Pseudomonas aeruginosa. Patients with suspected gonococcal infection require ceftriaxone 1g IM, as topical therapy is insufficient.
Prognosis
Most cases resolve within 1-2 weeks without treatment, but antibiotics reduce transmission and symptom duration. Corneal ulceration is a rare but serious complication. Patients should be advised to avoid sharing towels to prevent autoinoculation or spread to others.
Differential Diagnosis
Viral Conjunctivitis: watery discharge and preauricular lymphadenopathy
Allergic Conjunctivitis: intense pruritus and cobblestoning
Keratitis: decreased visual acuity and ciliary flush
Dacryocystitis: tenderness and swelling over the lacrimal sac
Blepharitis: chronic inflammation of the eyelid margins