Endogenous Methicillin-Resistant Staphylococcus aureus (MRSA) Endophthalmitis Presenting as an Anterior Chamber Abscess With Necrotizing Scleritis

To report a rare presentation of endogenous methicillin-resistant Staphylococcus aureus (MRSA) endophthalmitis with necrotizing scleritis manifesting as an anterior chamber (AC) abscess, and to highlight the diagnostic value of repeating AC sampling when clinical suspicion for infection remains high. A 29-year-old man developed a progressive AC mass and decreased vision one week after incision and drainage of an MRSA thigh abscess. Ocular symptoms progressed for two months before ophthalmic evaluation revealed a large AC lesion with hypopyon and early scleral thinning. An initial AC tap was negative; corticosteroids were associated with clinical worsening. A repeat AC tap demonstrated Gram-positive cocci, and cultures confirmed MRSA. Treatment with intravitreal vancomycin and ceftazidime, systemic antibiotics, and tapered corticosteroids led to improvement in visual acuity from light perception to 20/30 3.5 months after the initial eye exam. Endogenous MRSA endophthalmitis is uncommon and typically posterior; presentation as an AC abscess is rare. When clinical findings strongly suggest infection, repeat diagnostic sampling should be performed despite an initial negative result. Early targeted intravitreal antibiotics and coordinated subspecialty care can preserve vision.