An Unusual Infectious Cause of Abdominal Pain: Non-typhoidal Salmonella Aortitis Complicating an Endovascular Aortic Stent Graft

Non-typhoidal Salmonella (NTS) is a rare but life-threatening cause of infectious aortitis and mycotic aneurysm formation, predominantly affecting immunocompromised patients and those with pre-existing vascular pathology or prosthetic hardware. Diagnosis is frequently delayed due to its non-specific clinical presentation and the poor sensitivity of conventional blood cultures. A 73-year-old immunocompromised woman with a history of penetrating aortic ulcer and prior endovascular aortic stent graft placement presented with progressive abdominal pain and para-aortic soft tissue thickening encasing the infrarenal aorta. Blood cultures were negative; however, CT-guided peri-aortic tissue aspiration and metagenomic next-generation sequencing (mNGS; Karius test) identified Salmonella enterica serovar Enteritidis susceptible to ampicillin, ceftriaxone, levofloxacin, nalidixic acid, and trimethoprim/sulfamethoxazole. The most probable infection source was the patient’s prolonged daily consumption of unpasteurized eggs from backyard chickens. She was treated with intravenous (IV) ceftriaxone for 30 days followed by 18 months of oral cephalexin suppression, with significant radiographic improvement at three-month follow-up. Surgical intervention was deferred given her high operative risk from metastatic malignancy and multiple comorbidities. This case is notable for its documentation of culture-negative NTS aortitis complicating an endovascular stent graft, in which mNGS was essential for pathogen identification. It further highlights the importance of eliciting detailed dietary exposure history in high-risk patients, the novel diagnostic challenge posed by concurrent autoimmune disease mimicking non-infectious vasculitis, and the feasibility of antibiotic-only management in carefully selected surgical non-candidates.