SUMMARYWe present a rare case of endogenous endophthalmitis caused by Citrobacter koseri. A 69-year-old woman with a history of poorly controlled diabetes and a protracted urinary tract infection (UTI) presented with a painful swollen left eye. There was no history of eye surgery or trauma. Imaging revealed an abscess in the right kidney. Although endophthalmitis is very rare in healthy patient, it is more common in the immunocompromised. In this patient, several multiple system illnesses including poorly controlled diabetes appear to have worked synergistically to make endophthalmitis a realistic complication of an otherwise isolated and remote source of infection, in this case pyelonephritis. Endophthalmitis, in the absence of an obvious exogenous cause, should be investigated thoroughly to exclude metastatic microbial spread. In addition, chronic features of UTI in a patient with poorly controlled diabetes or who is otherwise immunosuppressed warrant the exclusion of an underlying renal abscess. BACKGROUND