Four days after uneventful phacoemulsification, a patient returns with pain, lid oedema, hypopyon and vitritis with visual acuity of counting fingers. Anterior chamber tap is sent for microscopy and culture. The organism most frequently isolated in this setting is:

• A Pseudomonas aeruginosa
• B Staphylococcus aureus
• C Streptococcus pneumoniae
• D Coagulase-negative Staphylococcus epidermidis ✓

Explanation

Coagulase-negative Staphylococcus epidermidis, a commensal of the lid margin and conjunctiva, is the commonest isolate in acute postoperative endophthalmitis after cataract surgery, accounting for roughly half of culture-positive cases. It typically produces a moderately severe presentation several days after surgery. S. aureus, streptococci and gram-negative organisms are less frequent but carry worse prognosis. This distinction guides empiric intravitreal vancomycin plus ceftazidime coverage.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.