Infiltrative keratitis is associated with which of the following microbial antigens?

Infiltrative keratitis is associated with which of the following microbial antigens?

• A. Microbial antigens (staph)
• B. Viral antigens
• C. Allergen antigens
• D. Fungal antigens

Answer: (A)

Infiltrative keratitis is driven by a hypersensitivity reaction to microbial antigens, most classically from Staphylococcus aureus. This means the corneal infiltrates are often sterile and result from the immune system reacting to staphylococcal antigens (often arising from lid disease like blepharitis), rather than from direct infection of the cornea. If it were viral or fungal antigens, you’d expect patterns typical of infectious keratitis: viral keratitis shows dendritic or geographic ulcers, and fungal keratitis often has feathery margins with white plaques. Allergic processes involve different, non-infectious eyelid/conjunctival reactions rather than localized sterile corneal infiltrates. So the best association is microbial antigens from Staphylococcus aureus.

Infiltrative keratitis is driven by a hypersensitivity reaction to microbial antigens, most classically from Staphylococcus aureus. This means the corneal infiltrates are often sterile and result from the immune system reacting to staphylococcal antigens (often arising from lid disease like blepharitis), rather than from direct infection of the cornea.

If it were viral or fungal antigens, you’d expect patterns typical of infectious keratitis: viral keratitis shows dendritic or geographic ulcers, and fungal keratitis often has feathery margins with white plaques. Allergic processes involve different, non-infectious eyelid/conjunctival reactions rather than localized sterile corneal infiltrates.

So the best association is microbial antigens from Staphylococcus aureus.