Stenotrophomonas maltophilia endogenous endophthalmitis in an immunocompetent eye in Australia

Background Stenotrophomonas maltophilia has increasingly become a significant hospital-acquired pathogen due to its multi-resistance and ability to colonize surfaces. While ocular infections caused by S. maltophilia are documented, endogenous endophthalmitis (EE) is rare with only six cases reported in adults, mostly in immunocompromised individuals from developing countries. Here, we present the first documented case of S. maltophilia-associated EE in an immunocompetent adult in Australia. A 43-year-old female presented with a two-day history of painful vision loss in her left eye. There was no preceding trauma, systemic illness, or history of intravenous drug use. Notably, she worked as a marine biology researcher and had recently been visiting the hospital often to see family. Examination revealed severe anterior chamber inflammation, hypopyon, and vitritis. Initial treatment included hourly dexamethasone 0.1% eye drops while awake, atropine 1% three times daily, a single vitreous tap, and injection of intravitreal vancomycin (1 mg/0.1mL), ceftazidime (2.25 mg/0.1mL), and voriconazole (0.05 mg/0.1mL). Cultures confirmed Stenotrophomonas maltophilia, and oral trimethoprim-sulfamethoxazole (160 mg/800 mg) 1.5 tabs three times daily was initiated but later switched to moxifloxacin 400 mg daily due to neutropenia. One-month post-discharge, the patient developed an inferior retinal detachment requiring vitrectomy with silicone oil. At six months, her visual acuity improved to 6/18.

S. maltophilia-associated EE is a rare clinical condition, especially in the absence of systemic symptoms. Despite the poor prognosis typically associated with endophthalmitis, this case resulted in a relatively good visual outcome (BCVA 6/18). This report highlights the necessity for further research to elucidate the epidemiology, risk factors, and optimal management strategies for this rare ocular condition.