A 30-year-old sexually active man presents with 24 hours of copious thick purulent discharge, lid oedema, chemosis, and preauricular lymphadenopathy. Within a day he develops a central corneal ulcer. Gram stain of the discharge shows abundant intracellular gram-negative diplococci. Which property of the causative organism explains the rapid corneal involvement?

• A It spreads only through pre-existing scleral thinning
• B It requires prior epithelial trauma to establish keratitis
• C It can penetrate intact corneal epithelium ✓
• D It colonises only devitalised stroma after healing of a conjunctival scar

Explanation

Neisseria gonorrhoeae is unique among common ocular bacteria in its ability to invade through histologically intact corneal epithelium via its pili and IgA protease, so a perforating corneal ulcer can develop within days of untreated hyperpurulent conjunctivitis. Most other bacteria require a break in the epithelium, which makes option B true for them but false here and therefore the strongest distractor.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.