Successful Management of Infective Native Infrarenal Abdominal Aortic Aneurysm Associated With Micrococcus luteus and Streptococcus mitis in a 77-year-Old Man

Background Infected native abdominal aortic aneurysm (INAAA) is a rare but life-threatening condition characterized by rapid progression and high mortality. Case Summary We report a 77-year-old male with a history of arterial hypertension, ischemic heart disease, and stage IVB hormone-sensitive prostate adenocarcinoma, presenting with lumbar pain and mild inflammatory activation, including leukocytes 8.8 ×10³/µL and C-reactive protein 3.6 mg/dL (normal <0.50 mg/dL). Computed tomography angiography (CTA) demonstrated a 50-mm infrarenal aneurysm, with periaortic inflammatory changes and a periaortic hematoma. A multidisciplinary decision, made 3 hours after admission, favored urgent open surgical repair with resection and in situ reconstruction. Midline laparotomy with debridement and resection of the affected aorta was performed; in situ reconstruction was carried out using a rifampicin soaked bifurcated Dacron graft covered with bovine pericardium with anastomoses to healthy aortic and iliac segments. Intraoperative cultures identified Micrococcus luteus and Streptococcus mitis , rare pathogens in this context. Targeted therapy included intravenous ceftriaxone during hospitalization, followed by oral amoxicillin-clavulanate and doxycycline for seven weeks. Histopathology confirmed chronic granulomatous abscessed inflammation. The postoperative course was uneventful, and the patient was discharged home on postoperative day 17. At six months, follow-up imaging demonstrated a patent reconstruction without signs of persistent infection. Conclusion These findings highlight the importance of early recognition, aggressive debridement, and coordinated multidisciplinary management in achieving optimal outcomes in INAAA, particularly when atypical microorganisms complicate diagnosis and therapeutic decision-making.