Evolving microbiology and treatment of extracavitary prosthetic graft infections

The authors report the microbiology and outcomes following an individualized treatment algorithm for extracavitary (EC) prosthetic graft infection, including the use of graft preservation and in situ graft replacement techniques. A retrospective 8-year review of 87 patients treated for EC prosthetic graft infections was carried out. The treatment algorithm included culture-specific antibiotic therapy, surgical site debridement with antibiotic bead placement, selected graft preservation with muscle flap coverage, or graft excision with in situ conduit replacement. Outcomes measured included death, limb loss, and recurrent infection. It was found that present-day management of EC prosthetic graft infections is associated with lower mortality and morbidity despite changes in microbiology and the increased application of graft preservation and in situ grafting treatments.     

Managing extracavitary prosthetic vascular graft infections: a pathway to success

Prosthetic vascular graft infections portend grave consequences if not treated expediently. Despite the low incidence of infection, the potential for limb loss or death greatly magnifies this complication. The surgical management of prosthetic graft infections has evolved over the last 2 decades. With the myriad therapeutic options now available, an algorithm is necessary to provide the optimal surgical treatment of Samson groups 1 through 5 extracavitary infected vascular prostheses. An extensive review of the literature was undertaken to evaluate the most effective management schemes. The authors found that 3 factors--Samson classification, bacteriology, and patient vascular anatomy--are vital to the surgical strategy. These 3 criteria were examined, and an algorithm was developed based on successful clinical and experimental results. This review provides a step-by-step rationale for the surgical management of extracavitary prosthetic graft infections according to the most successful reported outcomes.     

Efficacy of muscle flaps in the treatment of prosthetic vascular graft infections

Prosthetic vascular graft infection requires graft removal and often leads to limb loss. To determine whether vascularized muscle flaps could alter the course of graft infection, 18 mongrel dogs (18-29 kg) were randomized to one of three groups and underwent unilateral carotid artery bypass with 6-mm X 4-cm PTFE grafts. At implantation, the grafts were inoculated with Staphylococcus aureus, 2 x 10(7) organisms/wound. On Day 3, dogs with patent grafts underwent wound debridement, irrigation, and closure, and the treatment to which they had been randomized was carried out. Group A (n = 4, controls) received only dicloxacillin, 500 mg po bid, beginning on Day 4. Group B (n = 5) underwent transfer of a vascularized sternocephalicus muscle flap around the infected graft, but received no antibiotics. Group C (n = 5) underwent muscle transfer as in Group B and were given dicloxacillin as in Group A. Dogs were followed until anastomotic disruption occurred or for 60 days. Quantitative bacterial cultures were taken from sternocephalicus muscle and wound fluid at the time of debridement and at sacrifice. All dogs that received antibiotics without flaps or flaps without antibiotics (Groups A and B) experienced anastomotic disruption. Dogs that received both antibiotics and flaps (Group C) had a significantly lower incidence of hemorrhage (20%, P less than 0.05). At sacrifice, fewer bacterial colonies were cultured from muscle flaps of Group C as opposed to Group A dogs (0.05 +/- 0.02 x 10(5) vs 0.79 +/- 0.31 x 10(5), P less than 0.05). Muscle flaps with antibiotic therapy may prove to be effective treatment for infected prosthetic vascular grafts.     

Use of an antibiotic-bonded graft for in situ reconstruction after prosthetic graft infections.

We have developed an infection resistant vascular prosthesis by bonding rifampin to Dacron grafts with the use of a collagen matrix release system. The purpose of this study was to determine the efficacy of this antibiotic-bonded graft in resisting infection after an in situ reconstruction of a previously infected prosthetic bypass. Eighty-three adult mongrel dogs underwent implantation of a 3 cm untreated Dacron graft into the infrarenal aorta. This initial graft was deliberately infected, at the time of operation, with 10(2) organisms of Staphylococcus aureus by direct inoculation. One week later, the dogs were reexplored, the retroperitoneum debrided, and the animals randomized to undergo an end-to-end in situ graft replacement with either one of two types of prosthetic grafts: group I (collagen, n = 36) received control collagen-impregnated knitted Dacron grafts; group II (rifampin, n = 47) received experimental collagen-rifampin-bonded Dacron grafts. Each group of animals was then subdivided to receive one of four treatment protocols: (a) no antibiotic therapy, (b) cephalosporin peritoneal irrigation solution (cefazolin 500 mg/1000 ml) during operation and two doses of cephalosporin (cefazolin, 500 mg intramuscularly) postoperatively, (c) treatment as in protocol group b plus 1 week of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily), and (d) treatment as in protocol group b plus 2 weeks of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily). All grafts were sterilely removed between 3 and 4 weeks after implantation. There were no anastomotic disruptions and all grafts were patent at the time of removal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of three techniques for documenting Staphylococcus epidermidis vascular prosthetic graft infections

Staphylococcus epidermidis (S. epidermidis) vascular prosthetic graft infections are notoriously hard to detect. Three different techniques of determining whether vascular prosthetic grafts were infected using a dog model were evaluated. Aortic angiograms were compared with nuclear magnetic resonance (NMR) imaging and systemic norepinephrine (NE) kinetics to determine if either newer technique would be more reliable than standard angiograms. Twelve dogs were randomized to control (n = 6) or infected groups (n = 6). All dogs had a 5 cm section of their infrarenal aorta replaced with knitted Dacron vascular prosthetic graft. The grafts in the infected group were contaminated by soaking them in a broth containing S. epidermidis. NE production and clearance rates were calculated for all animals after an infusion of 3H-NE using the steady-state radionuclide tracer methodology. One week following graft insertion, dogs were reanesthetized, and the 3H-NE infusion and measurements were repeated. Standard angiograms and NMR imaging were also performed. Once all tests were performed, the prosthetic grafts were removed for cultures. Comparisons between the initial and final norepinephrine measurements for each group were made using the nonparametric Wilcoxon two-sample test, while comparisons between the groups were made by chi square or the Student's t test. Angiogram results were similar for control and infected animals. Angiograms missed disruption of the proximal anastomosis found in three of the six infected dogs at graft removal. None of the six control animals, while five of the six infected animals, had localized areas of high signal intensity on NMR imaging (P less than 0.01) suggesting abscess formation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Laparoscopic diagnosis and treatment of aortic vascular prosthetic graft infections in a porcine model.

OBJECTIVES: To study the feasibility and efficacy of experimental laparoscopy in the diagnosis of aortic graft infection in pigs. MATERIAL AND METHODS: Eight pigs had an aortic tube graft implanted and inoculated with either 5 x 10(4) or 10(6) CFU of Staphylococcus aureus ATCC 29213. Laparoscopy was performed after a median of 20 days with debridement and sampling for bacterial culture. Thereafter, the grafts were locally soaked in rifampicin and postoperatively, the pigs received rifampicin and ciprofloxacin orally for two weeks and were then sacrificed. RESULTS: All pigs developed graft infection. One pig died from severe clostridial septicaemia before laparoscopy could be performed. The remaining pigs had all samples for bacterial culture taken by laparoscopy from the inflamed tissue. The temperature dropped significantly after laparoscopy, and no macroscopic signs of infection presented at autopsy. However, only culture from one pig was without S. aureus at autopsy. CONCLUSIONS: Laparoscopy is a potential diagnostic tool for aortic graft infection and also affords the opportunity to carry out bacteriological sampling and local antibiotic treatment. The efficacy of laparoscopic treatment needs further evaluation.     

Successful treatment of an infected vascular graft with gentamicin beads

This short report describes the successful healing of an infected axillo-bifemoral graft by the insertion of Gentamicin beads, this technique cannot be recommended for all infected grafts the majority of which will have to be removed and replaced.     

Use of rifampin-soaked gelatin-sealed polyester grafts for in situ treatment of primary aortic and vascular prosthetic infections

BACKGROUND: In situ treatment of artery/graft infection has distinct advantages compared to vessel excision and extra-anatomic bypass procedures. Based on animal studies of a rifampin-soaked, gelatin-impregnated polyester graft that demonstrated prolonged in vivo antibacterial activity, this antibiotic-bonded graft was used selectively in patients for in situ treatment of low-grade Gram-positive prosthetic graft infections or primary aortic infections not amenable to excision and ex situ bypass. METHODS: In a 5-year period (1995-1999), 27 patients with prosthetic graft infection (aortofemoral, n = 18, femorofemoral, n = 3; axillofemoral, n = 1) or primary aortic infection (mycotic aneurysm, n = 3; infected AAA, n = 2) underwent excision of the infected vessel and in situ replacement with a rifampin soaked (45-60 mg/ml for 15 min) gelatin-impregnated polyester graft. All prosthetic graft infections were low grade in nature, caused Gram-positive bacteria (Staphylococcus epidermidis, 16; Staphylococcus aureus, 5; Streptococcus, 1), and were treated electively. Patients with mycotic aortic aneurysm presented with sepsis and underwent urgent or emergent surgery. RESULTS: Two (8%) patients died-1 as a result of a ruptured Salmonella mycotic aortic aneurysm and the other from methicillin-resistant S. aureus infection following deep vein replacement of an in situ replaced femorofemoral graft. No amputations or late deaths as the result of vascular infection occurred in the 25 surviving patients. Two patients developed recurrent infection caused by a rifampin-resistant S. epidermidis in a replaced aortofemoral graft limb and were successfully treated with graft excision and in situ autogenous vein replacement. Eighteen patients remain alive and clinically free of infection after a mean follow-up interval of 17 months. CONCLUSIONS: In situ replacement treatment using a rifampin-bonded prosthetic graft for low-grade staphylococcal arterial infection was safe, durable, and associated with eradication of clinical signs of infection. Failure of this therapy was the result of virulent and antibiotic-resistant bacterial strains.     

Experience with cryopreserved arterial allografts in the treatment of prosthetic graft infections

The authors present a retrospective study on 30 patients with prosthetic graft infection. Included are 25 patients with aortic graft infection, three with infection of a femorodistal bypass and two with infected axillofemoral grafts. There were 23 isolated primary prosthetic graft infections and seven aorto-enteric fistulas. Treatment consisted of graft excision and replacement with cryopreserved arterial homografts, harvested from brain-death multi-organ donors. The in situ technique was used in 27 cases. Eight patients died postoperatively and two deaths were from allograft related complications. The operative mortality rate was 11% for isolated aortic graft sepsis and the early limb salvage rate was 100%. Persistent or recurrent infection was noted in two cases. The mean follow-up of the series was 24.5 months and occlusive complications occurred in five patients (23%), which resulted in two major amputations. Serial CT scans showed abnormalities in six of the 22 survivors, all of them related to the aortic segment of the allograft. It is concluded that in situ reconstruction with cryopreserved arterial allografts represents an acceptable alternative, especially in the treatment of isolated aortic graft sepsis. Continued follow-up towards late deterioration and/or occlusive complications remains mandatory.     

血管移植物感染的防治策略

近年,血管腔内治疗得到迅速发展,但传统的血管移植手术仍是处理心血管疾病的重要手段,尤其对治疗周围血管疾病目前其还处于不可替代的地位。移植物感染是血管移植术后少见的并发症,目前报道的发生率为1％～6％,我科近20年资料的统计结果显示感染发生率为1．14％。术后移植物感染发生率不是很高,但产生的危害非常大,其可导致器官功能丧失、截肢,甚至危及生命,其中主动脉移植物发生感染引起的死亡率可高达33％～58％,腹股沟区移植物感染引起的死亡率相对较低,但可导致79％的下肢截肢率。     

Outcomes in the management of vascular prosthetic graft infections confined to the groin: A reappraisal

The management of vascular prosthetic graft infections confined to the groin continues to be controversial. To critically evaluate this problem, we reviewed the records of our vascular registry from December 1992 through February 1995 and found 17 incidences of groin sepsis involving a vascular prosthesis in 10 patients. These included a proximal prosthetic femoropopliteal bypass (n=6), an aortobifemoral graft limb (n=5), an ileofemoral bypass (n=3), a prosthetic femoral patch (n = 2), and an aortofemoral/femorofemoral bypass (n=1). The mean age of these patients was 65 years. Six patients were diabetic, four were on systemic steroids, and two were diabetic and on steroids. All infections were Szilagyi grade III including three in which the patients presented with local hemorrhage. Treatment consisted of irrigation, radical debridement with or without in situ graft replacement, and local rotational muscle flap coverage in nine cases, graft excision with extra-anatomic (obturator ileofemoral bypass) graft replacement in six cases, and excision alone in two cases. Of the 17 infections treated operatively and followed from 1 week to 18 months (median 5 months), eight (47%) showed no evidence of recurrence, six (35%) recurred, two (12%) caused early death, and one resulted in a thrombosed graft requiring extra-anatomic reconstruction. Of the nine infected grafts treated locally with muscle flaps, six showed recurrent infection from 3 weeks to 15 months and one thrombosed for a total local treatment failure rate of 78%. Only two grafts are free of infection at 4 and 5 months, respectively. Of the six incidences of infection treated with obturator bypass, four (66%) are free of infection and two resulted in patient death; both infections treated with excision alone were eradicated but resulted in a major lower extremity amputation. These data question the growing acceptance of debridement and local muscle flap coverage for the treatment of all prosthetic vascular graft infections confined to the groin, especially in patients who are diabetic or on systemic steroids.Presented at the Twentieth Annual Meeting of the Peripheral Vascular Surgery Society, New Orleans, La., June 10, 1995.     

Systemic effects of prosthetic vascular graft implantation

The effect of prosthetic vascular graft implantation on systemic complement activation, as well as leukocyte and platelet counts, was studied in rabbits. Animals underwent aortic clamping and declamping alone (group I) or with implantation of an externally supported PTFE graft (group II) or preclotted knitted Dacron graft (group III). Fifteen minutes after declamping, mild activation of complement reflected as a fall in CH50 to 72% of preoperative baseline values was observed in group I animals. Comparatively greater activation was seen in group II (43% baseline) and group III (28% baseline) animals. The differences between groups I and II (p less than 0.05) and I and III (p less than 0.01) were significant. The drop in platelet count was greater in group II (66% baseline) and group III (53% baseline) animals compared with group I (86% baseline). Neutrophil counts decreased in group I animals (75% baseline), but, again, this fall was more marked in group II (35% baseline) and group III (43% baseline) animals. The difference between groups I and II was significant (p less than 0.05). Similarly, monocyte count decreased in group I animals (80% baseline), which was also more marked in group II (32% baseline) and group III (31% baseline) animals. The differences between group I and groups II and III were significant (p less than 0.05 for each). These trends persisted throughout the first postoperative hour. These results suggest that the blood-surface interactions produced systemic effects in vivo.     

Intraperitoneal placement of gentamicin beads in the management of prosthetic graft sepsis

A simple and non-hazardous technique for intraperitoneal placement of gentamicin beads after excision of an infected prosthetic aortic graft is presented. It has been used successfully in six cases of aortic graft sepsis.     

Optimal prosthetic graft design for small diameter vascular grafts

Autogenous vein and arterial grafts, such as great saphenous veins and internal mammary and radial arteries, remain the gold standard conduits for vascular reconstruction. Expanded polytetrafluoroethylene (PTFE) grafts, which exhibit little inflammatory and thrombogenic reactivity, are the most commonly used material of choice for small diameter vascular grafts when autogenous grafts are not available. Several modifications of the basic graft have been attempted to enhance graft healing of expanded PTFE grafts, and little but definite experimental and clinical improvement has been achieved so far. The technique of vascular tissue engineering, in combination with stem cell research, may hold the key for the creation of a practical and successful small diameter prosthetic graft.     

Antibiotic-impregnated beads for the treatment of aortic graft infection

Infection of a prosthetic graft after replacement of the ascending aorta is an uncommon but life-threatening complication of surgery. We report the use of antibiotic-impregnated calcium sulfate beads in a patient with ascending aortic graft infection to provide localized, high-dose therapy to the infected region. Perigraft placement of antibiotic beads provides an alternative method for the treatment of aortic graft infection.     

Conservative treatment of vascular prosthetic graft infection is associated with high mortality

Background

The aim of this study was to identify patient-related and/or disease-related factors that influence outcomes in patients with vascular prosthetic graft infections.

Methods

Through the hospital patient administration system, between January 1997 and December 2007, a total of 44 patients were diagnosed with central prosthetic graft infections. Univariate and multivariate analyses were performed to define factors predictive of mortality.

Results

Thirty-three men and 11 women (mean age, 71 years) were included. There was considerable comorbidity. Coagulase-negative Staphylococcus and S aureus were isolated in almost 50% of the patients. The mean follow-up duration was 5 years, during which 20 patients (46%) died. The main causes of death were related to vascular disease. Conservative treatment with antibiotics was the only variable with significant predictive value on multivariate analysis (hazard ratio, 3.62; 95% confidence interval, 1.17-11.24; P = .02).

Conclusions

Conservative treatment of prosthetic graft infections was associated with high mortality; therefore, it should be limited to a specific group. Patients who are not capable of undergoing open repair may benefit from conservative management. Otherwise, aggressive open treatment seems indicated.     

Lateral femoral bypass for prosthetic arterial graft infections in the groin

Objective

Prosthetic arterial graft infections (PAGIs) in the groin pose significant challenges in terms of revascularization options and risk of limb loss as well as associated morbidities. Although obturator canal bypass (OCB) has been suggested for revascularization of the extremity in these cases, moderate success rates and technical challenges have limited widespread use. Our study analyzed lateral femoral bypass (LFB) as an alternative approach for the treatment of groin PAGIs.