A 57-year-old man is hospitalized with Streptococcus viridans endocarditis; intravenous ceftriaxone for 6 weeks will be initiated. History is significant for stage G5/A2 chronic kidney disease due to IgA nephropathy and hypertension. Placement of a left forearm arteriovenous fistula occurred 12 days ago. He does not yet require dialysis. Medications are lisinopril, furosemide, and sevelamer.

On physical examination, temperature is 37.0 °C (98.6 °F), blood pressure is 128/84 mm Hg, pulse rate is 77/min, and respiration rate is 17/min. BMI is 25. A grade 3/6 holosystolic murmur is present at the left sternal border. There is no pericardial rub. The arteriovenous fistula has a palpable thrill. The lungs are clear. There is no asterixis. There is no peripheral edema.

Which of the following is the most appropriate vascular access for antibiotic administration?