Nocardia brasiliensis endophthalmitis initially misdiagnosed as uveitis: a case report

BACKGROUND: Endophthalmitis caused by Nocardia brasiliensis is extremely rare and typically affects immunocompromised individuals, frequently leading to severe vision loss due to diagnostic delays. We report a case of N. brasiliensis endophthalmitis in an older man without prior history of systemic immunosuppression but with newly identified diabetes mellitus, characterized by an indolent initial course followed by fulminant progression. CASE PRESENTATION: A 67-year-old man without known systemic immunosuppression presented with a two-month history of recurrent right-eye pain and redness, followed by rapid vision loss and a hypopyon. Aqueous humor analysis and metagenomic sequencing identified N. brasiliensis. Despite intravitreal amikacin, systemic antimicrobial therapy, and subsequent pars plana vitrectomy with silicone oil tamponade, intraocular inflammation advanced, resulting in worsening corneal opacification, irreversible structural damage, and a final best-corrected visual acuity of light perception. CONCLUSIONS: N. brasiliensis endophthalmitis may progress rapidly and result in severe, irreversible ocular damage, even in patients without overt systemic immunodeficiency. Early microbiologic identification and prompt, targeted antimicrobial therapy combined with timely surgical intervention are critical, although visual outcomes may remain poor in advanced cases.