Which organism is commonly associated with post-surgical endophthalmitis?

• A. Pseudomonas aeruginosa
• B. Neisseria meningitidis
• C. Staphylococcus epidermidis
• D. Escherichia coli

Answer: (C)

Post-surgical endophthalmitis is most often caused by organisms that are part of the skin and periocular flora accidentally introduced during surgery. Staphylococcus epidermidis, a coagulase-negative staphylococcus, is the classic and most common culprit. It’s a frequent resident on the skin and conjunctiva and readily adheres to intraocular lenses or other implanted materials, forming biofilms that help it persist despite the eye’s defenses and antibiotics. Even a small inoculum can seed an endophthalmitis in the postoperative eye, making this organism the typical cause after routine procedures.

Other pathogens can cause endophthalmitis in different contexts—Pseudomonas aeruginosa, for example, is more often linked to rapid, destructive infections after trauma or contact lens use, while Neisseria meningitidis and Escherichia coli are not typical postoperative culprits.