Purulent Pericarditis and Mycotic Aortic Arch Aneurysm Caused by Salmonella Typhimurium: A Rare Case in an Immunocompromised Patient

Purulent pericarditis is a rare but life-threatening condition, and <i>Salmonella</i> Typhimuriumis an uncommon pathogen. Its simultaneous occurrence with a mycotic aortic aneurysm is exceptionally rare and has been documented only in a very limited number of cases. We describe the case of a 64-year-old woman with long-standing systemic lupus erythematosus managed with chronic corticosteroid therapy who presented with fever and pleuritic chest pain. Laboratory tests showed elevated inflammatory markers, and the electrocardiogram demonstrated diffuse ST-segment elevation with PR-segment depression. She was diagnosed with acute pericarditis and discharged with non-steroidal anti-inflammatory drugs. Nine days later, she returned with recurrent fever, chest pain, dyspnea, and orthopnea. Computed tomography revealed a large pericardial effusion and a saccular aneurysm of the aortic arch. Given the presence of arterial hypotension and echocardiographic signs of cardiac tamponade, urgent pericardiocentesis was performed with drainage of purulent fluid, and intravenous ceftriaxone was initiated on the first day. Pericardial fluid culture isolated <i>Salmonella</i> Typhimurium. Despite clinical and laboratory improvement, serial echocardiograms demonstrated progressive features of constrictive pericarditis. Due to the evolving constrictive pericarditis and the concomitant presence of a mycotic aortic arch aneurysm at risk of rupture, complete pericardiectomy and aortic arch replacement were performed. This case illustrates an exceptionally rare presentation of invasive non-typhoidal <i>Salmonella</i> infection manifesting exclusively with extra-intestinal symptoms and complications (purulent pericarditis and a mycotic aortic aneurysm). Early recognition, prompt pericardial drainage, targeted antibiotic therapy, and timely surgical intervention were essential for a favorable outcome, especially in an immunosuppressed patient.