Managing a Mycotic Thoracoabdominal Aneurysm: The Importance of Molecular Diagnostics

Pneumococcal mycotic aneurysms are rare and associated with significant mortality and morbidity. Early intravenous antibiotic therapy and surgical intervention is the mainstay of treatment. Pneumococci frequently autolyze in blood cultures, making microbiological diagnosis challenging. We present the case of a man in his mid 70s with multiple thoracoabdominal mycotic aneurysms. Surgery was performed to a threatening saccular aortic arch aneurysm. Samples were sent for microbiological analysis and all were culture negative. The samples were then referred for bacterial 16S ribosomal RNA sequencing, which revealed evidence of infection with Streptococcus pneumoniae.