Case Presentation: A 72-year-old male with diabetes mellitus presented with two-day right eye vision loss and floaters. Vitals showed tachycardia and hypotension. Physical examination was notable for a hypopyon of the right eye and pressure ulcers on the buttocks bilaterally. Labs returned with leukocytosis, lactic acidosis, and acute kidney injury. A maxillofacial CT scan revealed no retrobulbar stranding, soft tissue mass, or other fluid collection. Blood cultures were drawn on admission and later resulted in Citrobacter koseri. He was started on broad-spectrum intravenous antibiotics. Ophthalmology was consulted and performed B-SCAN which was negative for intraocular mass or retinal detachment followed by intravitreal tap and treatment with intravitreal vancomycin and ceftazidime. The vitreous culture also grew Citrobacter koseri. Infectious Disease was consulted and switched intravenous ceftazidime to intravenous moxifloxacin based on the culture results. CT of the orbit on day 5 showed right globe exophthalmos, thickening of the sclera, and surrounding soft tissue stranding with no retrobulbar fluid collections. The patient was put on prednisone for chemosis/proptosis. Intravitreal vancomycin and ceftazidime were administrated again on day 3 and amikacin was injected on days 6 and 9. However, the endophthalmitis was refractory to treatment and the patient had no light perception in the right eye and so he was taken to OR on day 14 for evisceration. On day 17 patient was noted to have vitritis of the left eye. A vitreal tap was performed along with intravitreal vancomycin and amikacin and ofloxacin, prednisolone ophthalmic suspension, atropine ophthalmic solution, and oral moxifloxacin. The vitreous culture of the left eye was negative. Due to the patient’s monocular status, pars plana vitrectomy was performed to preserve the vision of the left eye on day 18. On a 3-month follow-up with ophthalmology, the patient showed no signs of infection in the left eye with a best-corrected vision of 20/60.
Discussion: EE is rare and only accounting for 2-8% of cases of endophthalmitis. Citrobacter endophthalmitis is rarely reported in the literature. The diagnosis is clinical and is supported by positive cultures of the vitreous or aqueous fluid or positive blood cultures. The transient bacteremia resulting from underlying infections leads to intraocular invasion. Treatment of EE has 3 parts the one which most experts recommend is performing a vitreous aspirate followed by injection of intravitreal antibiotics and then systemic antibiotics. The penetration of antibiotics into the posterior segment of the eye after systemic administration is limited by blood-retinal barriers (BRB). The best-documented agents achieving therapeutic levels in the vitreous are meropenem, linezolid, and moxifloxacin. Vancomycin, cefazolin, ceftriaxone, ceftazidime, imipenem, and trimethoprim-sulfamethoxazole reach levels justifying their use as targeted therapy when a pathogen is identified, and the minimum inhibitory concentration of the isolate has been determined. Available data do not support the use of ciprofloxacin, levofloxacin, aminoglycosides, aminopenicillins, piperacillin, cefepime, and clarithromycin.
Conclusions: The role and timing of other treatment modalities, including vitrectomy, are still unclear. Quick and accurate diagnosis and prompt treatment with intravitreal antibiotics are key to preserving vision. Clinicians should be vigilant for endophthalmitis complicating systemic infections.