Post-cataract surgery endophthalmitis presenting at day 2–5 post-operatively with severe hypopyon and pain is most likely caused by which organism?

• A Staphylococcus epidermidis
• B Propionibacterium acnes (Cutibacterium acnes)
• C Streptococcus species or Gram-negative bacilli ✓
• D Candida albicans

Explanation

Early acute post-cataract endophthalmitis (onset within 1 week, especially day 2–5) with severe hypopyon, pain, and rapid progression suggests virulent organisms — Streptococcus species or Gram-negative bacilli (Pseudomonas, Klebsiella). Staphylococcus epidermidis causes the most common overall post-cataract endophthalmitis but tends to be more indolent (milder presentation at 3–7 days). Cutibacterium (Propionibacterium) acnes causes a delayed/chronic endophthalmitis appearing weeks to months post-surgery with white intracapsular plaque. Candida endophthalmitis is typically seen in IV drug users or immunocompromised patients.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.