How do you differentiate between viral and bacterial conjunctivitis in terms of diagnosis and treatment?

Distinguishing Between Viral and Bacterial Conjunctivitis

Viral conjunctivitis and bacterial conjunctivitis have distinct clinical presentations that guide diagnosis and treatment approaches, with viral cases typically being self-limited while bacterial cases may benefit from antibiotic therapy in moderate to severe presentations. 1

Clinical Presentation

Viral Conjunctivitis

• Presents with abrupt onset, often unilateral initially but frequently becomes sequentially bilateral 2
• Characterized by watery discharge rather than purulent discharge 3
• Typically accompanied by a follicular reaction of the inferior tarsal conjunctiva 2
• Often associated with concurrent upper respiratory infection 2
• Preauricular lymphadenopathy is commonly present, especially with adenoviral infections 2, 4
• May cause chemosis, eyelid swelling, and erythema 2
• Self-limited duration, typically resolving within 5-14 days without specific treatment 2, 5
• Severe cases may develop pseudomembranes, subepithelial corneal infiltrates, and conjunctival scarring 2

Bacterial Conjunctivitis

• Can be unilateral or bilateral 2
• Characterized by purulent or mucopurulent discharge 2, 3
• Presents with a papillary rather than follicular reaction 2
• Mattering and adherence of the eyelids on waking are strongly associated with bacterial etiology 5
• May be associated with concurrent bacterial otitis media, sinusitis, or pharyngitis, particularly in children 2
• Preauricular lymphadenopathy is less common than in viral conjunctivitis 2
• Most uncomplicated cases resolve in 1 to 2 weeks 5
• Corneal infection is a potential complication, particularly with virulent organisms like gonococcus 2

Diagnostic Approach

Key Differentiating Features

• Discharge type: Watery in viral vs. purulent/mucopurulent in bacterial 3
• Conjunctival reaction: Follicular in viral vs. papillary in bacterial 2
• Lymphadenopathy: More common in viral (especially adenoviral) 2, 4
• Associated symptoms: Upper respiratory symptoms often present with viral conjunctivitis 2
• Eyelid mattering: More prominent in bacterial conjunctivitis, especially upon waking 5

Special Considerations

• Gonococcal conjunctivitis presents with marked eyelid edema, bulbar conjunctival injection, purulent discharge, and can lead to corneal infiltrate or ulcer 2
• Herpes simplex virus conjunctivitis usually presents unilaterally with distinctive signs including vesicular rash or ulceration of eyelids 2
• Laboratory testing (cultures, PCR) may be useful in recalcitrant cases or when specific etiology identification is important 6

Treatment Approach

Viral Conjunctivitis

• Majority of cases are self-limited and do not require antimicrobial treatment 1
• Supportive care options include:
  • Artificial tears for symptomatic relief 1, 3
  • Cold compresses to reduce inflammation 3
  • Topical antihistamines for symptomatic relief 1
• Indiscriminate use of topical antibiotics should be avoided as viral conjunctivitis will not respond to antibacterial agents 1, 2
• Topical corticosteroids may be helpful in severe cases with marked chemosis, lid swelling, epithelial sloughing, or membranous conjunctivitis, but require close follow-up 1
• Patient education about high contagiousness is essential - encourage minimizing contact with others for 10-14 days from symptom onset 1
• Strict hand hygiene and surface disinfection are crucial to prevent transmission 4

Bacterial Conjunctivitis

• Mild bacterial conjunctivitis is usually self-limited and may resolve without specific treatment 1
• Topical antibiotics decrease the duration of bacterial conjunctivitis and allow earlier return to school or work 5
• For moderate to severe bacterial conjunctivitis (characterized by copious purulent discharge, pain, and marked inflammation):
  • Obtain conjunctival cultures if gonococcal infection is suspected 1
  • A 5-7 day course of broad-spectrum topical antibiotic is usually effective 1
  • No evidence exists demonstrating the superiority of any particular topical antibiotic agent 1
• Conjunctivitis secondary to sexually transmitted diseases such as chlamydia and gonorrhea requires systemic treatment in addition to topical antibiotic therapy 5

Important Considerations and Pitfalls

• Chronic and/or recalcitrant conjunctivitis may indicate underlying malignancy, such as sebaceous or squamous cell carcinoma 1
• Avoid indiscriminate use of topical antibiotics or corticosteroids 1
• Never use corticosteroid-containing preparations unless conjunctivitis is proven to be non-herpetic 7
• Ophthalmology referral is indicated for:
  • Conjunctivitis in neonates 3
  • Severe pain or decreased vision 3
  • Recent ocular surgery 3
  • Vesicular rash on eyelids or nose 3
  • Immunocompromised patients 3
  • Persistent or worsening symptoms despite treatment 7