A Case of PCI-Associated MRSA Aortitis Complicated by Aortic Rupture

Introduction

Infectious aortitis is a rare but life-threatening condition with highly non-specific symptoms, often leading to delayed diagnosis and increased morbidity and mortality. Most commonly associated with immunocompromised states, intravenous drug use, and recent intravascular interventions. The reported incidence of infectious aortitis ranges from 0.6–3%, with Staphylococcus aureus accounting for up to 28% of cases. Methicillin-resistant Staphylococcus aureus (MRSA)–associated aortitis carries particularly high mortality rates, reported between 15–50%, especially when diagnosis and definitive management are delayed.

CASE: A 77-year-old male with a past medical history of hypertension, diabetes mellitus, prostatic hyperplasia, and coronary artery disease status post recent percutaneous coronary intervention (PCI) to the left anterior descending artery presented with 5 days of abdominal pain, nausea, vomiting, dysuria, melena, and altered mental status. Hemodynamically stable initially. Computed tomography (CT) of the abdomen and pelvis revealed a 7.6 × 5.6 × 5.5 cm retroperitoneal conglomerate nodal mass encircling the abdominal aorta, raising concern for malignancy. The patient was admitted to the intensive care unit, and fine-needle aspiration of the mass was negative for malignancy. Blood cultures repeatedly grew MRSA, and the patient was diagnosed with MRSA infectious aortitis and started on daptomycin. The patient underwent exploratory laparotomy with retroperitoneal lymph node biopsies, which demonstrated microabscess formation and increased plasma cells within peri-aortic lymph nodes, consistent with an infectious process. Despite medical therapy, the patient acutely decompensated with worsening tachycardia and hemodynamic instability. Computed tomography angiography of the aorta demonstrated acute abdominal aortic rupture at the level of the renal arteries with surrounding retroperitoneal hemorrhage involving approximately 5 cm of the abdominal aorta. Both renal arteries maintained perfusion. The case was discussed urgently with a multidisciplinary team, and the patient was transferred to a tertiary care center for emergent vascular surgical intervention.

Discussion

Infectious (mycotic) aortitis results from bacterial seeding of the arterial wall, often facilitated by bacteremia following intravascular procedures such as PCI. In this case, recent coronary intervention likely served as the nidus for infection. Persistent MRSA bacteremia suggests biofilm-mediated infection, highlighting the limitations of antibiotic therapy alone. Colonization of the vasa vasorum is favored in large-caliber vessels such as the aorta due to slower blood flow, allowing progressive arterial wall destruction and aneurysm formation. This case underscores the importance of early recognition, source control, and timely surgical intervention, as delayed diagnosis is associated with catastrophic complications and high mortality. With the increasing reliance on percutaneous vascular procedures, awareness of infectious aortitis as a rare but fatal complication is critical, particularly in high-risk patient populations.

Conclusions

MRSA infectious aortitis is a rare but highly lethal condition, particularly in high-risk patients. Recent PCI may serve as a nidus for MRSA aortic infection. Antibiotic therapy alone may be insufficient due to persistent bacteremia and biofilm formation.