Mycotic aneurysms: uncommon pathogens and treatment conundrums

<b>Introduction.</b> Mycotic aneurysms, characterized by vessel wall dilation resulting from infections including bacteria, fungi, and viruses, are a rare but severe consequence of systemic infections. The term 'mycotic' was coined by William Osler to describe the first instance of a fungal-induced infected aneurysm. These aneurysms, accounting for 0.6% of aneurysms in Western countries, carry a higher risk of rupture compared to uninfected aneurysms. While the femoral artery, aorta, and intracranial arteries are commonly affected, pathogens causing mycotic aneurysms vary across regions. Diagnostic challenges arise from nonspecific symptoms such as fever, and discomfort. To prevent the substantial morbidity and mortality associated with mycotic aneurysms, timely identification and treatment are paramount. We present a case series highlighting mycotic aneurysms caused by some rare pathogens - <i>Salmonella Paratyphi A, Streptococcus pneumoniae</i>, and <i>Pseudomonas aeruginosa</i>. <b>Methods.</b> This case series involves three patients diagnosed with mycotic aneurysms due to unusual pathogens. We describe each patient's clinical presentation, medical history, physical examination findings, laboratory results, imaging studies, and the diagnostic process leading to the identification of the causative pathogens. <b>Results.</b> The first patient is a 70-year-old gentleman who presented with a ruptured infra-renal abdominal aortic pseudoaneurysm caused by <i>Salmonella Paratyphi A</i>. The second patient is a 66-year-old gentleman with a <i>Streptococcus pneumoniae</i>-associated descending thoracic aortic pseudoaneurysm. The third patient is a 70-year-old gentleman with a ruptured descending thoracic aortic aneurysm with an occult aorto-oesophageal fistula due to <i>Pseudomonas aeruginosa</i> infection. The description highlights unique clinical features, laboratory findings, imaging results, and the management approaches undertaken in each patient. <b>Conclusion.</b> Mycotic aneurysms, pose diagnostic challenges due to their nonspecific symptoms. Early identification and intervention are essential to mitigate the severe complications associated with these aneurysms. The presented cases underscore the need for a comprehensive approach to diagnosis and management, ensuring optimal outcomes for patients affected by mycotic aneurysms.