Case Presentation: A 92-year-old women with a medical history of hypertension, type 2 diabetes, and surgical resection of colon and renal cancer presented to the emergency department with high-grade fever and purulent sputum. She visited her primary care physician with the complaint of fever 5 days prior to visiting our hospital and was prescribed antibiotics and antipyretics without any effect. Her body temperature was 39.0 ºC, blood pressure was 132/66 mm Hg, pulse was 105 beats/min, and respiratory rate was 16 breaths/min with an O2 saturation of 98 % in room air. On physical examination, there was no abnormality suggestive of potential diagnostic clues. The initial blood test revealed elevated white blood cells and C-reactive protein. Contrast-enhanced computed tomography showed 56×57 mm thoracic aorta dilatation and peri-aortic infiltration. She was admitted to the intensive care unit with a suspected infectious aortic aneurysm, for which empiric antibiotic therapy with vancomycin and meropenem was administered. Soon after admission, her blood cultures tested positive for Streptococcus agalactiae, Group B Streptococcus (GBS). After consultation with cardiology and cardiovascular surgery, the patient was transferred to a university hospital and was treated conservatively considering her advanced age and worsened general condition. Twenty-six days after admission, the patient deceased after developing a hemorrhagic shock due to massive hematemesis.
Discussion: Infectious aortic aneurysms are a rare and life-threatening disease that have an extremely high mortality rate without surgical intervention. The most common causative organisms are Staphylococcus and Salmonella species. S. agalactiae are gram-positive bacteria belonging to GBS that typically colonize the human genital and gastrointestinal tracts, which are associated with a variety of infections including infectious endocarditis. However, it is uncommon for them to colonize in the aorta; thus, the formation of mycotic aneurysms is extremely rare. Previous reports suggest that over two-thirds of the infection caused by S. agalactiae occur in patients in nursing homes aged older than 65 years. This patient had a past history of diabetes mellitus and malignancy, which could be risk factors for a higher mortality rate.
Conclusions: Infectious aortic aneurysms are uncommon, but hold a high mortality rate. Patients with infectious aortic aneurysms present with nonspecific symptoms including fever, back pain, and abdominal pain, which could make the diagnosis more difficult. Clinicians need to be aware of such conditions because the pathogens become more diverse along with population aging and changes in disease complexity.