Case
A 71-year-old Japanese woman. She had no medical history included in
coronary risk factors and rheumatic disease. From the beginning of 2022,
the patient became aware of general malaise, and in May 2022, blood
sampling performed at another hospital revealed a high C-reactive
protein (CRP) level of 16.11 mg/dL. Therefore, the patient was referred
to our hospital for detailed examination. Upon the presentation day, she
complained of back pain and computed tomography scan revealed a thoracic
aortic aneurysm associated with Stanford type B aortic dissection
(Figure 1A). It was decided not to perform emergency surgery, and
conservative treatment with antihypertensive drugs was performed, but
the CRP level remained high. Fluorodeoxyglucose-positron emission
tomography (FDG-PET) showed SUV max-8.01 accumulation in the aortic arch
(Figure 1B, 1C). In addition to large vessel vasculitis (LVV), such as
giant cell arteritis, a close examination was performed focusing on
infectious aortic aneurysms from the beginning. Four times of blood
culture upon hospitalization were negative, serum procalcitonin levels
were not elevated (0.03 ng/mL; cut off 0.05 ng/mL), and since the
progression was long-term (about five months), we judged the possibility
of infection as low. Based on the results of FDG-PET, we diagnosed
LVV1. Glucocorticoid therapy was started at
prednisolone of 30 mg/day. Despite starting prednisolone, CRP level
remained positive; therefore, the blood culture was retested
andStreptococcus
pseudopneumoniae was identified (Figure 2A, 2B). The response to
penicillin G was well, and prednisolone was decreased and discontinued.
Infectious aortic aneurysms are often caused by Staphylococcus
species and Salmonella species 2.Streptococcus pseudopneumoniae is indigenous bacteria in the
human oral cavity and is involved in the exacerbation of chronic
obstructive pulmonary disease. To identify Streptococcus
pseudopneumoniae , it is necessary to confirm that the pneumococcal
capsule, which is a major feature of Streptococcus pneumoniae , is
not recognized and that it is resistant to optochin in a 5% CO2
environment3. Fatal manifestations such as meningitis
may be less frequent compared to Streptococcus pneumoniae . IfStreptococcus pneumoniae or oral microbiota is suspected but the
clinical course, such as severity, does not match, the possibility ofStreptococcus pseudopneumoniae infection should be considered.
Additionally, the differentiation
between LVV and infectious aortic aneurysms was reconfirmed to be
sometimes difficult especially when caused by rare pathogens. In order
to accurately differentiation between LVV and infectious aortic
aneurysms, it was considered necessary to make a comprehensive judgment
by combining FDG-PET and multiple biomarkers, such as procalcitonin and
presepsin, in addition to repeated blood cultures.