Infectious aortitis and mycotic aneurysms are rare but potentially fatal conditions that often present with nonspecific symptoms, delaying diagnosis and treatment. The growing use of endovascular interventions has introduced new pathways for infection, particularly in high-risk individuals with vascular implants. We report the case of a 67-year-old man with coronary artery disease who developed persistent lower back pain and systemic symptoms following peripheral angiographic catheterization and covered iliac stent implantation. Blood cultures repeatedly grew Staphylococcus lugdunensis (S. lugdunensis), a virulent coagulase-negative staphylococcus known for its biofilm-forming capacity. CT angiography and 18F-fluorodeoxyglucose (FDG) PET-CT revealed an infected aortic pseudoaneurysm with perivascular inflammation, consistent with infectious aortitis and device-related infection. Despite targeted intravenous antibiotics, bacteremia persisted, indicating failure of conservative management. Surgical intervention was planned but ultimately declined by the patient, who deteriorated and passed away shortly after discharge. This case highlights a rare instance of S. lugdunensis-associated infectious aortitis arising from a covered iliac stent. The persistent bacteremia despite appropriate antibiotic therapy strongly suggests biofilm-mediated infection, underscoring the limitations of medical therapy alone in managing device-associated infections. PET-CT proved instrumental in detecting metabolically active infection when anatomical imaging was inconclusive. Clinicians should maintain a high index of suspicion for infectious aortitis in patients with vascular implants presenting with systemic symptoms and persistent bacteremia. Early use of PET-CT and timely multidisciplinary evaluation are essential for diagnosis and management. This report adds to the limited literature on peripheral stent-associated infections, particularly those caused by S. lugdunensis, and underscores the need for heightened post-procedural vigilance in similar cases.