Case Presentation: A 70-year-old male with a past medical history notable for HFrEF, CAD, hypertension, hyperlipidemia, CKD, and CHRF presented to an outside emergency department with a two-month history of unintentional weight loss, nausea, and worsening lower abdominal pain radiating to the back. CT angiogram showed abnormal soft tissue enhancement around the infrarenal abdominal aorta. On presentation, the patient met none of the SIRS criteria. Laboratory findings showed elevated ESR and CRP. Blood cultures were drawn and the patient started on empiric antibiotics. The patient was transferred to our medical center for further workup. We considered infectious and rheumatologic etiologies, as well as lymphoma. The rheumatologic workup was essentially negative, and a biopsy was not feasible. However, blood culture rapid PCR came back positive for Streptococcus pneumoniae. This made infectious aortitis the leading diagnosis. On hospital day 8, blood culture results confirmed S. pneumoniae bacteremia. The source of the bacteremia was never identified despite a radiograph of the chest; MRI of the brain, sacrum, and lumbar spine; transthoracic echocardiogram, and CT of the face and mandible.On hospital day 10 the patient developed worsening lower abdominal pain with an increase in ESR and CRP. Repeat abdominal imaging showed a penetrating atherosclerotic ulcer of the infrarenal abdominal aorta. Vascular surgery was consulted and the patient underwent EVAR on hospital day 11. On hospital day 22, the patient was discharged in stable condition with plans to complete a six-week course of parenteral ceftriaxone.
Discussion: The final diagnosis was S. pneumoniae bacteremia with presumed infectious aortitis. Etiologies of infectious and non-infectious aortitis are listed in Table 1 (Ref.1). Rapid progression of mycotic aneurysm with and without rupture are described in many cases. This patient had a penetrating atherosclerotic ulcer, which is a component of acute aortic syndrome. It remains unclear whether the PAU resulted from the patient’s ASCVD alone or if the inflammatory process contributed, as this was never confirmed by tissue sampling. A theoretical relationship between atherosclerosis and infectious aortitis has been described, as ASCVD “could favor insemination of a microorganism through structural alteration of the aortic wall.”(Ref.2)
Conclusions: The medical management of the infectious process was guided by the initial blood cultures. This highlights the importance of obtaining blood cultures when the differential diagnosis includes infectious aortitis, as biopsy may not be feasible. A high index of suspicion is needed as patients may not meet SIRS criteria upon presentation. Furthermore, infections in the aorta may rapidly progress to aneurysm or ulcers. Therefore, these patients should be considered early for vascular surgery consultation, and serial abdominal exams should be performed with a low threshold to repeat imaging. In one study of 55 patients with infectious aortitis, 47 patients (86%) underwent surgery (Ref.2)
