(224) Cryptogenic Aneurysm Anomaly: A Rare Case Involving Multidrug-Resistant Streptococcus pneumoniae

Introduction: Cryptogenic mycotic abdominal aortic aneurysm (AAA) is a rare but severe complication of atherosclerosis, often presenting only upon rupture. Early diagnosis is critical for effective management and improving outcomes. This case underscores the need to consider Streptococcus pneumoniae as a potential causative agent in mycotic aneurysms. While S. pneumoniae accounts for only 0.6% of aneurysms in Western countries and cryptogenic mycotic aneurysms represent up to 3% of all AAA, it is essential for intensivists and surgeons to be aware of such possibilities in AAA management.

Description: A 55-year-old male with a 30-pack-year smoking history presented with subacute back pain. He met sepsis criteria with tachycardia and leukocytosis. Further evaluation revealed a 5.1 cm infrarenal AAA with a localized extraluminal leak, likely chronic. The patient underwent an emergency exploratory laparotomy, resection of the infected infrarenal aorta, ligation of the aorta, and right axillobifemoral bypass. Intraoperative findings included multiple pockets of purulent fluid around the aortic wall, and cultures identified multi-drug resistant S. pneumoniae. The patient was managed in the SICU and continued on a long-term antibiotic regimen. No extravascular source of sepsis was identified; transthoracic echocardiogram was negative for infective endocarditis, and blood cultures were negative for bacteremia.

Discussion: This case highlights the importance of thoroughly investigating primary or cryptogenic mycotic aneurysms. Distinguishing a cryptogenic AAA from secondary infections or extravascular causes, such as local injury or bacterial inoculation is crucial. Timely recognition and surgical intervention are essential to prevent adverse outcomes. Furthermore, negative blood cultures are not uncommon in such cases, emphasizing the need for surgical pathology in diagnosis. Despite the current era of prevalent antibiotic use favoring mycotic infections with Staph Aureus, S. pneumoniae should not be forgotten as a potential cause and PCR analysis may be required for diagnosis. This case serves as a reminder for clinicians to maintain a high index of suspicion when evaluating patients with back pain and sepsis without an obvious source.