Discussion
The morbidity and mortality rates of infectious aortic aneurysm rupture
are extremely high, with a poor prognosis for non-operative
cases.3 The causes of infectious aneurysms are as
follows: bacterial aneurysms caused by an infectious embolus due to
endocarditis; arteritis followed by an aneurysm due to bacterial
invasion of an arteriosclerotic blood vessel wall; infection of a
preexisting aneurysm; and traumatic, infectious pseudoaneurysms
including those caused iatrogenically.4 Our patient
had arteriosclerosis and a chronic dissecting lesion, which served as a
nidus of infection. In absence of a preexisting aneurysm, he was
diagnosed with arteritis-type aneurysm formation.
Salmonella is the most common causative organism for this type of
infection, followed by Staphylococci andStreptococci .5 In this case, AmpC-producingC. freundii was the causative organism, and required long-term
administration of carbapenem antibiotics. However, the antibiotics
caused pseudomembranous enteritis due to C. difficile , which
prolonged the duration of treatment. We administered Vancomycin and
Fidaxomicin to treat the C. difficile ; Fidaxomicin was
particularly effective in the patient. C. freundii is most often
found in patients who are immunosuppressed; however, our patient’s
immune status was normal.
Prevention of infections in prosthetic aortic grafts is important in the
overall treatment strategy and the following methods should be
considered: 1) meticulous removal of the abscess; 2) muscle and omental
flap wrapping;6 3) addition of antibacterial agents to
the prosthetic grafts, (e.g., rifampicin soaking);7 4)
the use of a homograft;8 and 5) extra-anatomical
revascularization.1 In such an emergency situation it
was impractical to obtain a homograft. Extra-anatomical reconstruction
was also non-viable for a TAAA requiring reconstruction of the major
abdominal branch. Therefore, methods 1-3 were used to avoid infection of
the grafts. If complete removal of the arterial wall containing the
infected tissue is intended in infectious TAAA, reconstruction of the
intercostal artery is not viable, and spinal cord ischemia is a concern.
In this case, widespread infection made it difficult to reconstruct the
intercostal artery and consequently led to paraplegia.