Preservation of Infected Aortic Grafts with Intra-Abdominal Abscesses by Percutaneous Drainage and Specific Antibiotic Therapy

Abstract

Aortic graft infection is a rare but lethal complication of aortic surgery. Standard treatment consists of sepsis control by graft excision, antibiotics, and securing flow to distal circulation. We describe 2 patients with a proven infection of a central vascular prosthesis who were unable to tolerate surgical intervention. Conservative therapy comprised drainage of abscesses and specific intravenous antibiotics directed at the cultured microorganisms. Both patients were discharged home with oral antibiotics after 6 weeks of hospitalization. As long as oral antibiotics were continued, no infectious complications occurred. Conservative treatment with antibiotics and drainage of intra-abdominal abscesses after ruptured abdominal aneurysm repair may lead to midterm survival in selected cases.

VASCULAR DISEASE MANAGEMENT 2012:9(11):E189-E192
Key words: aortic graft infection, antibiotic treatment

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Aortic vascular graft infection is an infrequent complication of aortic surgery. Standard treatment consists of antibiotic therapy and graft removal followed by extra-anatomic bypass or in situ repair with autologous material, like a deep femoral vein.¹ The mortality rate of this approach varies from 11% to 88%.2-4 Furthermore, recurrent infection or thrombosis of extra-anatomic bypass leads to amputation in 11%-43% of patients.^2,3,5

In some cases, graft removal is not feasible because of poor clinical condition of the patient after emergency aneurysm repair, a hostile abdomen or severe comorbidity. Different methods of preserving the infected graft have been reported.⁶ We describe 2 patients with infected grafts, unfit for immediate graft removal. The first was treated only by specific antibiotic treatment and the second was treated with percutaneous drainage and antibiotic treatment aimed at the cultured microorganism.

Case Report

Patient A is a 78-year-old male with a history of Billroth 1 gastric resection, coronary artery bypass grafting, lung carcinoma (T1N0M0 treated with radiotherapy), a venous supragenual femoral-popliteal bypass, percutaneous transluminal angioplasty, chronic obstructive pulmonary disease GOLD 2, hypertension, and hypercholesterolemia. He presented with a ruptured aneurysm of the abdominal aorta with a diameter of 7.0 cm on computed tomography (CT) angiography with no signs of infection or inflammation.  Emergency open aneurysm repair was performed with a Dacron prosthesis (DuPont).  After surgery, he was admitted to the intensive care unit (ICU) for 2 days where he developed pneumonia (Escherichia coli), which was treated with ceftriaxone, a broad-spectrum cephalosporin.  At return to the vascular surgical ward, fever persisted. Common postoperative causes of infection were ruled out. CT angiography showed intraperitoneal and retroperitoneal abscesses (Figure 1). CT-guided puncture of only the periprosthetic hematoma was performed. The other abscesses were not punctured and drained. Culture revealed a Listeria monocytogenes.   Although L monocytogenes infection is commonly seen in patients with close contact to milk and cheese products, our patient had no history of eating or working with these products. The graft infection was discovered 2 weeks after initial operation, and was considered an unfavorable period for a relaparotomy. We believed graft removal was not feasible in this patient because of his poor nutritional status, recent pneumonia and recent postoperative status. Therefore we started conservative treatment. Antibiotics were switched to amoxicillin and gentamicin, according to sensitivity of the cultured micro-organism and administered intravenously during 6 subsequent weeks. Control abdominal CT showed a reduction of the abscesses (Figure 2). Blood levels of C-reactive protein (CRP) returned toward a normal value of 6 mg/L. The patient was discharged after a hospital stay of 61 days, with continuation of amoxicillin by mouth. An abdominal CT scan 15 months after discharge showed no signs of infection.

Patient B is a 73-year-old male with a history of subtotal colectomy (because of polyposis coli), transient ischemic attack, type 2 diabetes mellitus, coronary artery bypass grafting, and chronic obstructive pulmonary disease. Because of an asymptomatic juxtarenal aneurysm of the abdominal aorta with a maximum diameter of 7.1 cm, open aneurysm repair was performed with a Dacron tube prosthesis. Two days later he underwent a relaparotomy because of a fascia defect. Recovery was uneventful and he was discharged 2 weeks later. However, 3 days after discharge he returned to the emergency room with abdominal sepsis, a CRP of 238 mg/L and leukocyte count of 20.2 x109/L. Abdominal CT showed an intra-abdominal fluid collection in the right upper quadrant, left lateral, as well as fluid in and directly next to the surgically closed old aneurysm sac (Figure 3). Both the collections in the right upper quadrant, left lateral and next to the old aneurysm sac were drained under CT guidance. Culture revealed a Corynebacterium jeikeium. We presumed that the prosthesis was colonized with the same microorganism. We considered him unfit for definitive surgical treatment because of his severe sepsis and hostile abdomen and therefore started the patient on vancomycin and rifampicin. During his admission, the patient developed several new intra-abdominal abscesses, which were all drained percutaneously.

Fluid cultures showed a Staphylococcus epidermis (sensitive for clindamycin and rifampicin) and blood cultures showed an E coli. After 84 days, with a CRP of 25 mg/L and a leukocyte count of 4.2 x109/L, the patient was discharged home with clindamycin and rifampicin by mouth. At long-term outpatient department followup, blood levels of CRP, leukocytes slowly decreased towards normal values. Antibiotics were continued until levels of CRP and leukocytes were normal, more than 3 years later. Figure 4 shows a CT image 3 years after discharge without any signs of graft infection.

Discussion

We describe 2 patients treated with antibiotics and percutaneous drainage for infected Dacron aortic grafts prosthesis with intra-abdominal abscesses, because they were unfit for standard surgical treatment. Aortic graft infection is a rare but serious complication.⁷ The majority (68%) of graft infections occur with a late onset, more than 4 months after graft implantation.⁸ It is thought that early infections are influenced by perioperative procedures and caused by more virulent organisms such as Staphylococcus aureus or gram-negative bacilli. Most common causative pathogenic organisms for graft infections are Staphylococci and E coli.⁴  The patients described in this case report had both an early onset graft infection caused by L monocytogenes and C jeikeium, respectively. Central graft infections caused by these micro-organisms are very unusual. Only 7 cases of aortic grafts infected with L monocytogenes are described in the literature. It is frequently seen in cases involving milk and raw cheese.¹⁵ The normal flora of the skin contains C jeikeium, but C jeikeium is an infrequent cause of graft infections.

Although the treatment strategies for vascular graft infections are evolving, the basic principles remain unchanged. The first immediate treatment priority should focus on sepsis control and securing flow to distal circulation.¹ Sepsis control is ultimately done by removal of the graft and complete debridement of devitalized tissues, thereby eliminating the source of infection. In a study by Santini et al, partial graft excision led to infection of the residual graft in all patients.⁸ Subsequent control of flow to distal circulation is considered essential to avoid loss of limbs and other ischemic complications like bowel ischemia. Surgical options for revascularization are numerous. Classically, the extra-anatomic bypass was the preferable option. However, shortcomings of the extra-anatomical bypass are a low patency, a lengthy procedure, a relatively high amputation rate and difficulty of extra-anatomic routing (especially in the inguinal region).^9,10 Therefore in situ reconstruction options have been attempted such as prosthetic graft replacement, rifampicin-impregnated graft replacement (cryopreserved), allograft replacement, and autologous graft replacement. A recent meta-analysis by O’Connor et al demonstrated a significantly worse outcome for extra-anatomic bypass compared to in situ bypass options in terms of amputation, conduit failure, recurrent infection and mortality.¹¹ Also, rifampicin-bonded prosthesis was associated with fewer amputations, conduit failures and early mortality compared to cryopreserved allograft and autologous grafts. Cryopreserved allograft and autologous grafts were superior over rifampicin-bonded grafts with regard to recurrent infection and late mortality. New silver-coated in situ grafts had less susceptibility for resistance to antibiotics, though the risk of recurrent infection remains significant.^12,13

Graft removal remains essential in the definitive treatment of graft infection. However, in some cases, patients are inoperable. Both our patients had early graft infections of Dacron aortic graft prosthesis with intra-abdominal abscesses, which precluded early definitive surgery because they were in a poor health status and had a hostile abdomen. Therefore, they were treated by intravenous antibiotics directed against the cultured micro-organisms, and in the second case this was combined with percutaneous drainage of the abscesses. This conservative treatment for infected aortic grafts with intra-abdominal abscesses is described in the literature; however, there is no consensus about the duration of antibiotic treatment.^6,14,15 In a retrospective analysis by Saleem et al, the 5-year survival rate of 44 patients with an infected central graft was computed. Twenty-two of these patients were treated by standard surgical care, 9 patients were treated by drainage, and 13 patients received antibiotics alone.  The only significant predictive factor (hazard ratio 3.62; P=0.02) for mortality was treatment solely with antibiotics.¹⁶ Although this report shows that the outcome remains poor in patients with infected aortic grafts, we believe that with correct patient selection, midterm success can be accomplished with antibiotic treatment with or without drainage. We continued intravenous antibiotic treatment based on general well being, temperature, laboratory values, and follow-up CT-scanning for at least 6 weeks. Subsequently, patients were discharged home with oral antibiotics.  As long as oral antibiotics were continued, there were no infectious complications. We therefore believe that in selected cases, as in patients with a poor health status or hostile abdomen with an infected Dacron aortic graft prosthesis, conservative treatment (antibiotics and drainage) may be an alternative for standard surgical treatment of vascular graft infection.

Conclusion

Some patients with infected aortic prosthetic grafts with intra-abdominal abscess are unable to tolerate the standard surgical treatment of graft excision and revascularization. In selected cases, conservative treatment with antibiotics and drainage of abdominal abscesses after ruptured abdominal aorta aneurysm surgery may lead to midterm survival.

References

1. Mussa FF, Hedayati N, Zhou W, et al. Prevention and treatment of aortic graft infection. Expert Rev Anti Infect Ther. 2007;5(2):305-315.
2. Reilly LM, Stoney RJ, Goldstone J, Ehrenfeld WK. Improved management of aortic graft infection: the influence of operation sequence and staging. J Vasc Surg. 1987;5(3):421-431.
3. Seeger JM, Pretus HA, Welborn MB, Ozaki CK, Flynn TC, Huber TS. Long-term outcome after treatment of aortic graft infection with staged extra-anatomic bypass grafting and aortic graft removal. J Vasc Surg. 2000 Sep;32(3):451-459; discussion 460-461.
4. Swain TW 3rd, Calligaro KD, Dougherty MD. Management of infected aortic prosthetic grafts. Vasc Endovascular Surg. 2004;38(1):75-82.
5. Liedenbaum MH, Verdam FJ, Spelt D, de Groot HG, van der Waal J, van der Laan L. The outcome of the axillofemoral bypass: a retrospective analysis of 45 patients. World J Surg. 2009;33(11):2490-2496.
6. Calligaro KD, Veith FJ, Yuan JG, Gargiulo NJ, Dougherty MJ. Intra-abdominal aortic graft infection: complete or partial graft preservation in patients at very high risk. J Vasc Surg. 2003;38(6):1199-1205.
7. Perera GB, Fujitani RM, Kubaska SM. Aortic graft infection: update on management and treatment options. Vasc Endovascular Surg. 2006;40(1):1-10.
8. Santini C, Baiocchi P, Venditti M, et al. Aorto-femoral graft infections: a clinical and microbiological analysis. J infect. 1993;27(1):17-26.
9. Lehnert T, Gruber HP, Maeder N, Allenberg JR. Management of primary aortic graft infection by extra-anatomic bypass reconstruction. Eur J Vasc Surg. 1993;7(3):301-307.
10. Verhelst R, Lacroix V, Vraux H, et al. Use of cryopreserved arterial homografts for management of infected prosthetic grafts: a multicentric study. Ann Vasc Surg. 2000;14(6):602-607.
11. O’Connor S, Andrew P, Batt M, Becquemin JP. A systematic review and meta-analysis of treatments for aortic graft infection. J Vasc Surg. 2006;44(1):38-45.
12. Batt M, Jean-Baptiste E, O’Connor S, et al. In-situ revascularisation for patients with aortic graft infection: a single centre experience with silver coated polyester grafts. Eur J Vasc Endovasc Surg. 2008;36(2):182-188.
13. Batt M, Magne JL, Alric P, et al. In situ revascularization with silver-coated polyester grafts to treat aortic infection: early and midterm results. J Vasc Surg. 2003;38(5):983-989.
14. Belair M, Soulez G, Oliva VL, et al. Aortic graft infection: the value of percutaneous drainage. AJR Am J Roentgenol. 1998;171(1):119-124.
15. Saleem BR, Berger P, Zeebregts CJ, Slart RH, Verhoeven EL, van den Dungen JJ. Periaortic endograft infection due to Listeria monocytogenes treated with graft preservation. J Vasc Surg. 2008;47(3):635-637.
16. Saleem BR, Meerwaldt R, Tielliu IF, Verhoeven EL, van den Dungen JJ, Zeebregts CJ. Conservative treatment of vascular prosthetic graft infection is associated with high mortality. Am J Surg. 2010;200(1):47-52.

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Editor’s Note: Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript received February 22, 2012, provisional acceptance given May 1, 2012, final version accepted May 18, 2012.

Address for correspondence: Izaäk F. Kodde, MD, Amphia Hospital, General Surgery, Molengracht 21, Breda, 4818CK, Netherlands. Email: if.kodde@hotmail.com