|Year : 2021 | Volume
| Issue : 2 | Page : 223-228
Endovascular stents––boon or bane? A case report of spondylodiscitis following aorto-illiac stent insertion
Sushma Krishna1, Sumanth Kaiwar2, Amrithlal A Mascarenhas2, Adarsh Raghurama2
1 Department of Microbiology, St. Martha’s Hospital, Bengaluru, Karnataka, India
2 Department of Spine Disorders, St. Martha’s Hospital, Bengaluru, Karnataka, India
|Date of Submission||13-Apr-2020|
|Date of Decision||13-May-2020|
|Date of Acceptance||19-Sep-2020|
|Date of Web Publication||24-May-2021|
Department of Microbiology, St. Martha’s Hospital, Bengaluru 560001, Karnataka.
Source of Support: None, Conflict of Interest: None
Spondylodiscitis after aorto-illiac stent insertion for the management of peripheral vascular disease is a rare but serious complication. We report the first case that we encountered as it provided insight into the device-related infections and the treatment dilemma that we went through. Within a week following insertion, a 43-year-old patient developed symptoms of infection. Imaging, laboratory cultures, and inflammatory markers were sought. The patient was treated with antibiotics for over six months to achieve a complete cure. Acute stent-graft infections require prompt and aggressive management. Centers specialized in carrying out endovascular stent insertions should monitor this device-related infection as a health-care-associated infection. The case may be looked on as a learning experience for the spine surgeons, vascular surgeons, microbiologists, and the infection control team of the hospital.
Keywords: Aortic stent, infection, spondylodiscitis
|How to cite this article:|
Krishna S, Kaiwar S, Mascarenhas AA, Raghurama A. Endovascular stents––boon or bane? A case report of spondylodiscitis following aorto-illiac stent insertion. Indian Spine J 2021;4:223-8
|How to cite this URL:|
Krishna S, Kaiwar S, Mascarenhas AA, Raghurama A. Endovascular stents––boon or bane? A case report of spondylodiscitis following aorto-illiac stent insertion. Indian Spine J [serial online] 2021 [cited 2021 Dec 4];4:223-8. Available from: https://www.isjonline.com/text.asp?2021/4/2/223/316663
| Introduction|| |
Peripheral stents are increasingly used for the treatment of peripheral arterial disease or of arterial occlusive diseases. However, all implanted devices potentially carry varying degrees of risk of infections. The incidence of Endo Vascular Aortic Stent (EVAR) infection following aortic repair is reported to be around 0.4% to 0.7% with an estimated mortality ranging from 27.4% to 36.4%. These infections extend along the continual line of tissues involving the spine and may even cause spinal infections. Cases of vertebral osteomyelitis, spondylitis and spondylodiscitis have been reported by studies as uncommon but serious complications following endovascular aortic repairs.,,, We report the first case of spondylodiscitis that we encountered with aorto-illiac stent infection, following its insertion for the management of peripheral vascular disease, probably the first from this part of the country.
| Case Report|| |
A 43-year-old chronic smoker, with no known co-morbidities, presented with fever on the third postoperative day following the insertion of a vascular stent for Peripheral Vascular Disease (PVD). He subsequently developed low backache on the tenth postoperative day and presented himself to the spine clinic. On examination––Pain, Sensory, Motor, and Sphincter change (PSMS) grading was negative, L4, L5 was tender on palpation. Straight leg raising test was positive at 90° bilaterally. The power in extensor and flexor hallucis longus was 5/5 bilaterally. Peripheral pulses were present with normal sensations. Investigations revealed TLC of 16,000 c/mm of blood, ESR 90 mm/hr, and CRP 95 mg/L. His blood cultures were sent which grew Pseudomonas aeruginosa, a pan-sensitive strain. Urine culture revealed no growth of organisms. MRI spine showed transitional vertebra at the lumbosacral junction with L4–L5 being the last well-formed disc [Figure 1] and spondylodiscitis at L4–L5 level with epidural abscess [Figure 2]. His liver function tests were mildly deranged (SGOT 40U/L, Direct S. Bilirubin 0.86 mg/dl) and pro-calcitonin value of 2.03ng/mL suggested the risk of sepsis. He was started on meropenem 1g IV TID in the first week. Debridement, curettage along with posterior decompression and instrumented fusion L3 through L5 [Figure 3] was carried out. The abscess was drained and the debrided tissue was sent for cultures. The tissue also grew Ps. aeruginosa with the same sensitivity pattern as that of blood. Genxpert MTB/RIF from the debrided sample remained negative for Mycobacterium tuberculosis. The histopathology report revealed inflammatory infiltrates with no granulomas but with features consistent with discitis. Meropenem was continued, and Inj Amikacin 500 mg OD and ceftazidime 1g IV BD were added for the next eight weeks. The patient was discharged with oral faropenem 200 mg BD, ciprofloxacin 500 mg BD for a further four weeks. ESR was 57 mm/hr, CRP was 15 mg/l and blood cultures were sterile at discharge.
|Figure 1: Sagittal T2 image of whole spine showing the last well-formed disc is L4–L5 suggesting transitional vertebra at the lumbosacral junction. C7––thick red arrow, T12––dotted red arrow, and L4––thin red arrow|
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|Figure 2: Axial image of MRI spine at the time of diagnosis showing high signal intensity and enhancement of L4–L5 suggestive of spondylodiscitis with an epidural abscess|
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|Figure 3: Postoperative X-ray spine AP and lateral view showing endovascular stent along with L3-L5 instrumentation|
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The patient presented again at the end of the next month with persisting backache. ESR was 55 mm/hr, CRP 24 mg/L; however, blood culture remained negative. MRI was repeated which showed signal changes at L2-L3 level - suggestive of possible spread of infection to adjacent levels [Figure 4]. FDG PET CT was done which revealed spondylodiscitis at L2-L3 with a focal uptake at the cross over of iliac stents with a mural plaque in the anterior wall of aortic bifurcation - infective /inflammatory changes [Figure 5]. Further course of treatment options included – a) remove the stent, b) re-explore the column for longer fixation, or c) choose conservative antibiotic therapy. A consensus opinion was taken from multiple specialties (vascular surgeon, microbiologist) and the patient was treated conservatively with full 3 months of IV meropenem again with serial monitoring of creatinine values. By the end of this course of 3 months, the back pain had resolved, there was a decline in ESR (21 mm/hr) and CRP (4.11 mg/l) levels trending to normal values and blood cultures remained sterile. A repeat spine MRI showed a complete resolution of infection [Figure 6]. The patient did not report back to the spine clinic with any further symptoms for the next six months. However, the stent remained in-situ, surgically unexplored.
|Figure 4: MRI showing signal changes suggestive of adjacent level infection at L2–L3 level|
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|Figure 5: PET CT image showing spondylodiscitis changes at L2–L3 level with no other enhancing or hyper metabolic lesions in other bones or viscera. A focal FDG uptake at the cross-over of iliac stents and a mural plaque in the anterior wall of aortic bifurcation was seen––suggestive of infective/inflammatory changes|
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|Figure 6: Fusion at the infected level L3 through L5 seen. No visible signal changes at any other level were seen––suggestive of resolution|
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| Discussion|| |
Spondylodiscitis associated with aortic stent infection is a devastating complication of post- endovascular stenting. These infections pose both a diagnostic and therapeutic challenge to the treating clinician. If left unattended, these infections may end up in graft disruption, hemorrhage, or sepsis. Neurological deficits/ bone destructions are reported rare in the literature. A combination of thorough clinical evaluation, microbiological investigations and imaging is the right approach in the management of aortic graft infections.
The causative organisms in aortic repairs and EVAR procedures predominantly are gram-positive-cocci like Staphylococcus aureus, Staphylococcus epidermidis, Enterococci Spp, etc but gram-negative bacilli such as E.coli and others have also been reported. The adherence capacity of Psuedomonas aeruginosa isolated in this case to the devices and subsequent biofilm formation cannot be underrated. The risk factors for developing pyogenic spondylitis include pre-existing skin/soft tissue infections, infective endocarditis, postoperative wound infection, or any foci of infection in the body. No such contributory risk factors were noted in this patient secondary to stent infection. The isolation of the organism probably indicates nosocomial origin, although it was not possible to culture the organism from the device.
The clinical manifestations of aortic graft infection vary according to the duration that has elapsed since the procedure and the virulence of the bacteria responsible for the infection. This patient had an early onset infection by 72h of graft insertion with a typical presentation of fever and leukocytosis. The presentation of late-onset infections (those occurring more than 4 months after surgery) tends to be more elusive with non-specific signs and symptoms. Moreover, Pseudomonas aeruginosa, a known virulent pathogen, probably would have contributed in an acute presentation. The route was likely a hematogenous spread (positive blood culture) through the middle sacral artery supplying the L4–L5 disc space, coupled with a local extension from the graft site to the L2–L3 region. Both routes are known in causing the spread. However, a specific time interval between the endovascular procedure and continuous spondylodiscitis has not been reported for inference.
Conservative approach may often be the treatment of choice or standard care for spondylodiscitis and is expected to be effective. Surgery however is indicated if there is a neural compression or excessive vertebral body destruction as in case of invasion by resistant organisms or if the response to conservative therapy is not satisfactory., The patient showed early signs of sepsis-like deranged LFT and elevated PCT with positive blood culture. To eliminate the foci of infection in the spine and to reduce the bacterial load, it was considered imperative to debride and drain, as unnecessary delay would lead to bone destruction and a long-term complication of kyphosis. Although the patient was on trial antibiotic therapy, the early results did not seem to be promising. Hence early surgery was considered in this patient.
There is no clarity on the therapy or the empirical therapy, the choice of drug or its combinations, or the duration to treat the graft infections. In the absence of treatment guidelines, the tried optimal duration of antibiotics ranges from 2 weeks to 1 year, a minimum of 4–6 weeks of IV, followed up by 6 months of oral therapy. The Infectious Disease Society of America (IDSA) attests long-term suppressive antimicrobial therapy for intravascular device-related infections as efficacious and well-tolerated in preventing signs of infection relapse. Oral antibiotics with high bioavailability are often used for long term suppression. The antibiotic of choice has to be based on the antimicrobial susceptibility tests and the correct dosage has to be administered depending on the MIC values for bone tissue penetration. This patient after having considered all the possible approaches required six months of antibiotics to achieve a complete cure. The response was monitored throughout with supportive inflammatory markers and serial radiographs. Patient’s compliance and adherence to therapy needs to be specially highlighted as most long term antibiotic therapies grapple with this challenge.
Removal of infected material (stent) is recommended as its presence may cause recurrent infections. If the infection persists/recurs after conservative antibiotic therapy, surgical treatment is recommended for these patients carrying mortality and morbidity of up to 20%. It is however the surgeon’s decision to operate considering the age, risks, and expected outcome. In the review study by Megaloikonomos PD et al. involving fifteen cases of spondylitis transmitted from an infected aortic graft, nine cases inclined towards surgery and graft removal. On consultation with the vascular surgeon, the stent remained in-situ in our patient.
CRP (C-Reactive Protein) and ESR as in any other infection, may be regarded as sensitive tools not just for evaluating infection but also for assessing treatment response. The values started to fall during the initial phase of treatment, began to rise again with persisting/recurrent infection, and finally hit the baseline after the completion of 6-month therapy. Spinal infections mostly have a sequel- hence early screening or diagnosis becomes important to prevent further complications. FDG PET in this case played a significant role in picking up both the stent and the spine infection at L2–L3 level.
Besides maintaining the aseptic precautions during the shunt placement, the near sterile location where the procedure is carried out such as OT or interventional radiology suite becomes one of the important factors. This patient was operated outside and further details were not available. Antibiotic prophylaxis designed for the surgery in most places (first-generation cephalosporins) would not have an adequate anti-pseudomonal cover and this is something to consider for device-related infections. Local antibiograms with epidemiology and sensitivity pattern may be useful in respective setups to prevent health-care-related infections.
A high index of suspicion is required to seek appropriate investigations. Multi-disciplinary consultations with microbiologists, infectious disease specialists, vascular surgeons, interventional radiologists, and orthopedicians are required in its management. A timely referral to the spine specialist from vascular surgery may help in rapid diagnosis. Centers specializing in endovascular treatment should monitor this device-related infection under health-care-associated infections.
| Conclusion|| |
Acute stent-graft infections, though rare, require prompt and aggressive management to reduce mortality and morbidity. The diagnosis must initially be based on a high index of suspicion. Imaging, laboratory cultures, and inflammatory markers are to be sought for confirmation and require serial monitoring. After assessing the risk-benefit tradeoff on a case-to-case basis, conservative long term antibiotic treatment or surgical treatment may be chosen as the optimal therapy.
Authors thank Dr. Rajesh Helavar, Consultant Radiologist, for his inputs on the radiological images.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]