Question:medium
Late-onset endophthalmitis after intraocular lens implantation is most commonly caused by?
Late-onset endophthalmitis after intraocular lens implantation is most commonly caused by?
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Chronic, indolent post-cataract endophthalmitis hides in the capsular bag: P. acnes.
Updated On: Jun 24, 2026
- Staphylococcus epidermidis
- Pseudomonas
- Streptococcus pyogenes
- Propionibacterium acnes
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The Correct Option is D
Solution and Explanation
The discriminating word in this stem is late onset. Endophthalmitis following cataract surgery with an intraocular lens is classified by how soon symptoms appear, and each time window has its own signature organism. If the infection erupts acutely within the first few weeks, the usual offender is a coagulase-negative staphylococcus such as Staphylococcus epidermidis introduced from the patient ocular surface flora. The picture described here, however, is the delayed or chronic variety that smoulders months after surgery with low-grade recurrent inflammation that paradoxically responds to steroids and then relapses. That indolent course is the hallmark of Propionibacterium acnes, now called Cutibacterium acnes, an anaerobic gram-positive rod that hides within the residual lens capsular bag and resists clearance. The two remaining choices, Pseudomonas and Streptococcus pyogenes, produce fulminant, rapidly destructive acute endophthalmitis and do not fit a late presentation. Matching the clinical tempo to the organism, the late-onset post-IOL endophthalmitis is most commonly due to Propionibacterium acnes. \[\boxed{\text{Propionibacterium acnes}}\]
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