Citrobacter koseri Endophthalmitis Following Intravitreal Fluocinolone Acetonide Implant Injection

Citrobacter koseri is a gram-negative bacillus primarily found in the gut. Exogenous endophthalmitis caused by C. koseri is exceedingly rare, with most reported cases occurring secondary to ocular trauma and resulting in poor visual outcomes. This report presents a case of a 76-year-old patient who developed endophthalmitis following a fluocinolone acetonide intravitreal injection administered for diabetic macular edema. A vitreous biopsy and intravitreal injection of vancomycin and ceftazidime were performed upon presentation. The vitreous sample culture was positive for C. koseri. The patient responded well with ultimate resolution of the infection and return of pre-infection visual acuity without a vitrectomy.