|Year : 2014 | Volume
| Issue : 1 | Page : 26-28
Mycotic Aneurysm of Iliac Artery: A Rare Complication of Salmonella Infection
Sunil Joshi, Nivedita Mitta
Department of General Surgery, Division of Vascular Surgery, St. John's Medical College and Hospital, Bengaluru, Karnataka, India
|Date of Web Publication||9-Oct-2014|
Department of General Surgery, Division of Vascular Surgery, St. John's Medical College and Hospital, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Mycotic aneurysms as a result of salmonella arteritis are rare in the era of broad spectrum antibiotics. However, few cases have been reported in cases of immunosuppression, presence of cardiovascular prosthetic materials or intravenous drug addiction. Though Salmonella infections cause aortitis and aortic aneurysms in elderly patients with atherosclerosis, it is rare to have common iliac artery aneurysms in young adults. High index of suspicion and aggressive investigation is required to detect these cases as the clinical presentation may be vague. Management of mycotic aneurysms is challenging, requiring emergency surgery. We hereby present a successful management of salmonella mycotic aneurysm of iliac artery in a young adult with no atherosclerotic risk factors.
Keywords: Arteritis, enteric fever, mycotic aneurysm, Salmonella
|How to cite this article:|
Joshi S, Mitta N. Mycotic Aneurysm of Iliac Artery: A Rare Complication of Salmonella Infection. Indian J Vasc Endovasc Surg 2014;1:26-8
| Introduction|| |
Mycotic aneurysms as a result of microbial arteritis are rare with a reported incidence of 0.06-0.65%.  In the present era of advanced antibiotics, they are rare except in the case of immunosuppression, vascular interventions, presence of cardiovascular prosthetic materials or intravenous drug addiction.  Though Salmonella More Details infections cause aortitis and aortic aneurysms in elderly patients with atherosclerosis, it is rare to have common iliac artery aneurysms in young adults.  Hereby, we encountered a case of salmonella mycotic aneurysm of iliac artery in a young adult, which was a diagnostic challenge and was managed successfully.
| Case Report|| |
A 25-year-old male presented to Orthopedics Department with flank pain of 2 week's duration that started insidiously, was continuous, dull aching and nonradiating with no associated gastrointestinal or genitourinary symptoms. He was treated as enteric fever with positive WIDAL titers 1-month prior to presentation. His fever had subsided, but malaise, loss of appetite, and abdominal discomfort persisted. MRI spine incidentally showed suspicious vascular lesion for which vascular consultation was sought. On examination, vitals were stable, no associated cardiovascular risk factors. Abdominal examination revealed tenderness in the right flank, no other abnormalities. Right lower limb was edematous with dilated veins over thigh and all peripheral pulses were palpable. Routine investigations were normal. Blood, stool, urine cultures were negative. WIDAL test at the time of admission was negative. Computed tomography (CT) angiography of the abdominal aorta and both lower limbs revealed bilobed fusiform aneurysm of right common iliac artery at the bifurcation measuring 5.2 × 4.6 × 2.8 cm. There was thrombosis of right common iliac veins extending into Inferior vena cava and right hydroureteronephrosis [Figure 1].
|Figure 1: The bilobed aneurysm involving common iliac artery bifurcation|
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He was started on intravenous cefotaxime and anticoagulants. Patient was planned for surgical treatment of aneurysm with distal revascularization. Ureteric stenting was done 2 days prior to plan procedure. Under general anesthesia, extra-anatomical femoro-femoral crossover bypass was performed using reversed saphenous vein graft from right thigh through bilateral vertical groin incisions [Figure 2]. Once distal revascularization was achieved, the aneurysm was approached through right flank. Extensive inflammation was encountered with areas of necrotic tissue. The right ureter was identified and isolated. Proximal and distal arterial control was achieved. The aneurysm was bilobed, friable and involved common iliac, external and internal iliac arteries. The aneurysm was excised, and adjacent necrotic tissue was debrided [Figure 3]. Common iliac, external iliac, and internal iliac artery arteries were debrided till healthy segment and were closed with two layers of 6-0 prolene sutures. Distal pulses in right lower limb were palpable at the end of the procedure. After washing the retroperitoneal cavity, the wound was closed in layers. Patient withstood the procedure well, requiring two blood transfusions. Recovery was uneventful except for seroma of the groin wound. Patient was continued on anticoagulation and 6 weeks antibiotics. Ureteric stent was removed after 6 weeks. Histopathology showed inflamed aneurismal wall [Figure 4]. The culture from the aneurismal wall was negative.
|Figure 4: Histopathology, inflammatory cell infiltrate but cultures were negative|
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| Discussion|| |
Mycotic aneurysm (or infective) aneurysms are localized, irreversible, vascular dilatations caused by weakening and destruction of the vessel wall by invasive organism establishing infective arteritis. They pose one of the challenging conditions in the field of vascular surgery.  Mycotic aneurysm is a rare event, especially after the introduction of antibiotics. In 1885, Osler provided the first comprehensive description of mycotic aneurysm. The prevalence of infected aneurysms in adults, produced by microbial arteritis, is estimated to be 0.06-0.65%. 
Salmonella, a motile Gram-negative, facultative, anaerobic bacilli of enterobacteriaceae has a predilection for endothelium, especially when it is diseased.  Arteritis can develop as a result of bacteremia or contiguous spread from adjacent infection. When infection is established suppuration, localized perforation and rapid destruction of the arterial wall often lead to aneurysm rupture before the diagnosis is made. 
The clinical presentation may be insidious. Patients often present with fever and progressive vague pain in the anatomical region of the aneurysm as seen in our case. Pain and fever are the most common presenting symptoms. In a recent series, leukocytosis and elevated C-reactive protein were found in 79% of the patients, and fever was apparent in 48%; 76% of the patients complained of pain.  Rupture is also common before diagnosis; 24% had frank rupture, and 61% showed contained rupture.  Sometimes, patients may present with pressure or inflammatory involvement of adjacent veins and ureter as in this case. Distal embolization and vascular compromise may be seen in few patients.
When mycotic aneurysm is suspected, blood cultures, complete blood cell count, and erythrocyte sedimentation rate should be obtained, followed immediately by institution of antibiotic therapy. CT findings indicative of infection includes the presence of a saccular aneurysm in otherwise normal arteries, multilobulated aneurysms, eccentric aneurysm with a narrow neck, perianeurysmal fluid or gas, hematoma, perianeurysmal enhancement, disruption of intimal calcification, or osteomyelitis in an adjacent vertebral body. 
Patients with positive blood cultures and an arterial aneurysm should be considered to have an infected aneurysm until proven otherwise. Conversely, negative blood cultures are not sufficient to exclude mycotic aneurysms such as our case, possibly due to antibiotic therapy. Investigators have noted positive cultures in only 50-70% of cases.  Furthermore, intra-operative Gram stains of the aneurysm wall are positive in only 20-30%. 
Early surgical intervention along with prolonged antibiotics remains mainstay of the treatment. The traditional treatment for mycotic aneurysm is to debride all infected tissue, oversew the arterial stumps, and perform revascularization through uninfected tissue planes using autogenous conduit.  The main determinants of prognosis include the location of the aneurysm, presence of rupture, virulence of the infecting organism and patient's immune status.  Only few cases of Endograft repairs have been reported but the outcomes are yet to be evaluated. 
To conclude, salmonella mycotic aneurysm can be seen in peripheral arteries of young adults with no atherosclerotic risk factors. A high index of suspicion is required to detect mycotic aneurysms in young adults. Early surgical intervention is essential to improving outcomes of this challenging entity.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]