Two days after routine intravitreal anti-VEGF injection, a patient presents with pain, hypopyon and vitritis. Culture of the aqueous is sent. The organism most commonly isolated in post-injection endophthalmitis is:

• A Staphylococcus aureus
• B Streptococcus viridans
• C Pseudomonas aeruginosa
• D Coagulase-negative Staphylococcus (Staphylococcus epidermidis) ✓

Explanation

Post-injection endophthalmitis is most often caused by lid and ocular surface flora, and coagulase-negative Staphylococcus, chiefly S. epidermidis, accounts for the majority of culture-proven cases, followed by S. aureus and streptococci. Streptococcal infections tend to be more fulminant with worse visual outcomes. Pseudomonas is a rare but devastating cause. Lid hygiene, povidone-iodine preparation and prompt recognition remain the main preventive measures.

Reference: Kanski's Clinical Ophthalmology, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.