Question

Late-onset endophthalmitis after intraocular lens implantation is most commonly caused by?

• A. Staphylococcus epidermidis
• B. Pseudomonas
• C. Streptococcus pyogenes
• D. Propionibacterium acnes

Hint:

Chronic, indolent post-cataract endophthalmitis hides in the capsular bag: P. acnes.

Answer 1

The Correct Option is D

Step 1: Separate the timing categories of post-operative endophthalmitis after cataract surgery with intraocular lens (IOL) implantation: acute (within about 6 weeks) versus chronic or LATE onset (after 6 weeks).
Step 2: Acute post-operative endophthalmitis is most commonly caused by coagulase-negative staphylococci, especially Staphylococcus epidermidis. That answers the acute, not the late, scenario, so option A is the acute culprit.
Step 3: Late or chronic post-operative endophthalmitis is characteristically caused by Propionibacterium acnes (Cutibacterium acnes), a slow-growing anaerobic gram-positive bacillus that sequesters in the lens capsular bag and causes an indolent, recurrent, granulomatous inflammation that improves transiently with steroids.
Step 4: Pseudomonas and Streptococcus pyogenes cause aggressive acute, often virulent endophthalmitis, not the indolent late form, so options B and C are excluded.
Step 5: Hence the most common cause of LATE-onset endophthalmitis after IOL implantation is Propionibacterium acnes, option D.