Streptococcus pyogenes presenting as infrarenal abdominal aortic mycotic aneurysm: Exploring the potential for conservative management

Infrarenal abdominal aortic mycotic aneurysm (MAA) is an uncommon and life-threatening condition caused by septic emboli that degrade the arterial wall. Standard treatment involves antibiotic therapy, aneurysm resection, and reconstruction of the affected area. However, in patients with significant comorbidities, surgery presents substantial risks, raising the question of whether conservative treatment might be a viable therapeutic option. An 80-year-old male with a history of aorto-monoiliac prosthesis placement for an infrarenal abdominal aortic aneurysm presented with fever, malaise, and lower back pain. Initially diagnosed with pyelonephritis, imaging CT scan revealed a dilated aorta with suspicious infected collections but no active bleeding. PET-CT demonstrated hypermetabolism confirming an active infectious focus. The patient was diagnosed with Szilagyi Grade III MAA. Blood cultures revealed an infection by Streptococcus pyogenes, a microorganism that is extremely infrequently associated with mycotic aneurysms. Due to comorbidities, conservative management with suppressive antimicrobial therapy was chosen. After 12 months of follow-up, the patient remains asymptomatic with negative blood cultures and disappearance of perianeurysmal soft tissue mass on follow-up CTA. MAA is a rare and fatal condition requiring early detection to prevent severe complications. Diagnosis relies on imaging studies. Standard treatment involves antibiotics and surgery, but in elderly patients with comorbidities, a conservative approach is a viable option. Treatment should be individualized and discussed by a multidisciplinary team.