A 73-year-old man with a history of end-stage renal disease (on hemodialysis for 6 years), hypertension, and diabetes mellitus type 2 presented with worsening pain and swelling of the left upper extremity brachiocephalic arteriovenous fistula. The patient was having night sweats for a few days prior to presentation. He was started on intravenous cephalosporin therapy at his outpatient dialysis unit as the blood cultures grew Staphylococcus aureus. On examination, the fistula was hard, and there was skin degeneration with oozing in the area which appeared to be a pseudoaneurysm (Figure, left panel). Computed tomography scan of the arm with contrast demonstrated approximately 4.3-cm mid-segment thrombus in the arteriovenous fistula that was likely infected. The patient also complained of worsening blurry vision and left eye redness and pain. Ocular examination revealed conjunctival hyperemia and pus in the anterior chamber (hypopyon) with poor red reflex (Figure, right panel). These findings were suggestive of endogenous endophthalmitis in the setting of dialysis access-related bacteremia, later confirmed by B-scan ultrasound. He was treated with intravitreal vancomycin and cefazolin in addition to systemic antibiotics. The arteriovenous fistula was ligated with excision of the infected pseudoaneurysm and the clot for source control. Maintenance hemodialysis was continued using a catheter. Although the vitreous cultures remained negative, his eye signs gradually improved, with complete resolution of hypopyon by day 4 of admission (Figure, right panel). He continued to have residual visual defects but was otherwise stable at discharge. Of note, the patient did not have any other metastatic infectious complications that are commonly associated with Staphylococcus bacteremia such as infective endocarditis, osteomyelitis, or septic emboli to the chest or brain.
Vascular access-related bacteremia and consequent metastatic infectious complications are associated with significant morbidity and recurrent hospital admissions among hemodialysis patients. Central venous catheters have been associated with the highest risks of death, infection, and cardiovascular events compared to other types of vascular access,1 and current guidelines recommend an autogenous arteriovenous fistula as the preferred vascular access for hemodialysis. However, arteriovenous fistulas are not without complications. Vascular pseudoaneurysms tend to occur at the needle puncture sites of the arteriovenous fistula and may harbor a thrombus which acts as a nidus for infection. These aneurysms may also rupture spontaneously, necessitating emergency ligation. Patients with pseudoaneurysms should be monitored closely for complications and promptly referred for intervention when thrombosis or signs of imminent rupture, such as pain and degeneration of the overlying skin, are detected.2
Endophthalmitis is a potentially vision-threatening condition that can result from exogenous or endogenous sources, the former being more common.3 Staphylococcus aureus and Streptococci are the most common pathogens implicated in endogenous bacterial endophthalmitis.4 Although extremely rare,5 it can occur as an isolated metastatic complication of arteriovenous fistula infection, as in our case. It is primarily a clinical diagnosis supported by culture of intraocular fluids, although a negative culture occurs in approximately 30% of the cases.4Timely administration of intravitreal antibiotics with or without vitrectomy is the mainstay of therapy. The best visual outcomes usually occur in cases caused by coagulase-negative staphylococci, and the worst outcomes are in those cases caused by streptococci, Bacillus species, and fungi. Without appropriate treatment, the symptoms can quickly worsen, leading to loss of vision; therefore, it is important to exclude endophthalmitis by thorough ocular examination when dialysis patients present with symptoms suggestive of eye infection.
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-Eddy Jose Dejesus, MD, Harini Bejjanki, MD, Abhilash Koratala, MD
This article originally appeared in the January issue of The American Journal of Medicine.
