Microbial evolution of vascular graft infections in a tertiary hospital based on positive graft cultures.

BACKGROUND: Vascular graft infections are a serious complication in vascular surgery. Correct antibiotic therapy targeted to the most likely infecting species is essential to treat these patients, although the bacterial epidemiology and pathogenesis are still not completely understood. We analyzed the behavior of vascular graft infections and the microbiologic patterns of resistance. METHODS: A 10-year (2008-2018), single-center, retrospective cohort study was performed of all patients admitted with vascular graft infection identified by positive direct graft cultures. An extensive microbiologic study was performed to analyze the bacterial strains, antibiotic resistance and sensitivity, and prevalence stratified by the year. RESULTS: A total of 72 vascular graft infections with positive graft cultures occurring in 65 patients were found. Their mean age was 67 ± 9.6 years, and 85% were men. Infection-related mortality was 11%. Of the 65 patients, 14 had undergone aortobifemoral bypass, 13 axillofemoral bypass, 5 femorofemoral bypass, 27 femoropopliteal bypass, and 4 femoral endarterectomy with synthetic patch angioplasty. The median interval from the index procedure to infection was longer for intracavitary than for extracavitary grafts (P = .011). Of the 72 infections, 48 were monomicrobial and 24 were polymicrobial. Gram-negative bacteria were predominantly identified in intracavitary graft infections (54%). In contrast, gram-positive bacteria were most frequent in the extracavitary graft group (58%). Multidrug-resistant bacterial species occurred more frequently in early graft infections (P = .002). Throughout the study duration, an overall decrease in gram-positive infections and an increase in gram-negative infections was observed, especially in extensively drug-resistant strains. A similar progression was found in all nosocomial infections. CONCLUSIONS: The present study has shown that vascular graft infection microbiology changed in accordance with graft location and interval to infection from revascularization surgery and had also evolved over the study period with patterns similar to those for all nosocomial infections. This highlights the importance of studying the specific microbiology of each healthcare center and its relationship to vascular graft infections to achieve the best treatment possible.

Prosthetic Graft Patency in the Setting of a Polymicrobial Infection in Swine (Sus scrofa).

BACKGROUND: In the setting of vascular injury, vein interposition graft is the preferred conduit, but may have limited availability. This study seeks to develop a large animal model assessing the graft performance of polytetrafluoroethylene (PTFE) and Dacron in the setting of a polymicrobial infection. METHODS: Thirty-seven animals were placed into 4 groups for a 21-day survival period. Six-millimeter PTFE or Dacron interposition grafts were placed in the right iliac artery with a standardized bacterial inoculation. Native vessel with and without contamination served as control groups. The inoculant was 1 × 107 of genetically labeled Pseudomonas aeruginosa and Staphylococcus aureus. The primary end points were graft patency (determined by duplex ultrasound and necropsy) and graft infection (culture with molecular analysis). Secondary end points included physiological measurements, blood cultures, laboratory data, and histopathology. RESULTS: PTFE and Dacron had similar infection rates of 85.7% and 75%, respectively. There was no significant difference in infectious organisms between graft materials. PTFE and Dacron exhibited bacterial ingrowth and transmigration to the intraluminal portion of the conduit. Forty-five percent of the Dacron group and 40% of the PTFE group remained patent at postoperative day 21 (P = 0.98). Clinical data, including white blood cell count, percent neutrophils, and lactate, did not vary significantly between groups. CONCLUSIONS: PTFE and Dacron perform similarly in terms of infection rates and graft failure as both have a propensity toward bacterial ingrowth and occlusion when compared with controls. This is a valid animal model to assess graft performance in the setting of polymicrobial infection and provides an avenue for studying novel prosthetic conduits.

Bacterial Colonization of Thrombosed Dialysis Arteriovenous Grafts.

In the absence of obvious infection, an abandoned arteriovenous graft (AVG) is generally left in place. This has been thought to be the best solution in view of the surgical procedure that would be required for its removal. However, there are reports of occult infection in these retained AVGs that can lead to significant infectious complications. In addition, there is evidence that abandoned, retained AVGs may contribute to the inflammatory state that exist in association with dialysis patients. This observational report of 100 cases of thrombosed AVG in which the thrombus was cultured at the time of thrombectomy demonstrated a significant degree of bacterial colonization in these cases without evidence of bacteremia. It is proposed that this could be the mechanism by which occult infection in an abandoned, retained AVGs occurs.

A case of thrombosis of intra-atrial extracardiac conduit and left pulmonary artery due to infective endocarditis after modified Fontan operation.

Previous studies have reported that the extracardiac Fontan procedure has excellent outcomes and a lower incidence of postoperative complications than the lateral tunnel procedure. However, thromboembolic events that occur after the Fontan procedure are a well-known cause of morbidity. We experienced a case of thrombosis of intra-atrial extracardiac conduit and the left pulmonary artery 2 years after a modified Fontan operation due to infective endocarditis (IE) despite prophylactic antiplatelet therapy. The patient underwent reoperation. The conduit in the right atrium (RA) was excised, and the thrombus in the vessels was removed. Because the fibrous tissue in the RA around the conduit was firm, the tissue was used as the "tunnel" for the Fontan route between the IVC and the ePTFE graft outside the RA instead of replacement using another alien graft. He was discharged on postoperative day 45 and was medicated with coumadin and aspirin. He is now being followed in our outpatient clinic and is still without any sign of infection.

An adverse event of suprapubic catheter SPC insertion. A call for updating the existing guidelines.

The suprapubic catheter (SPC) is a useful and widely used tool in urological practice. However, complications can arise from its insertion or ongoing care. We add to the literature a case of an adverse event of its insertion where it has gone through a vascular graft and recommending updating the SPC insertion guidelines.

Malnutrition, infection and arteriovenous fistula failure: is there a link?

INTRODUCTION: The histology of neointimal hyperplasia, the primary cause of arteriovenous fistula (AVF) stenosis, resembles the histology of atherosclerosis. We evaluated classic atherogenic risk factors such as hypertension, smoking, diabetes, cholesterol, and evaluated the role of expanded risk factors such as: cytomegalovirus (CMV), Helicobacter pylori (H. pylori), Chlamydia pneumoniae (C. pneumoniae), infection, and malnutrition, as possible causes of AVF failure in hemodialysis (HD) patients. METHODS: AVF of 91 HD patients were monitored by on-line blood flow measurement (Qac); levels of albumin, fibrinogen, C-reactive protein and plasma cholesterol were recorded. Nutrition was evaluated via the Malnutrition Inflammation Score and the normalized protein intake (nPCR). Seropositivity to CMV, C. pneumoniae and H. Pylori were assessed. RESULTS: Twenty-one patients had at least one episode of vascular access thrombosis; 17 patients had stenotic lesions. Analysis of survival tables revealed that patients who had high IgG CMV antibody levels had a higher probability of AVF failure than patients with lower CMV antibody levels. The difference in the empirical survival functions was statistically significant when we stratified by CMV antibody levels, unlike H. pylori or C. pneumoniae. In a logistic regression model, CMV, increased cholesterol, and decreases in nPCR and Qac significantly increased the risk of AVF failure. CONCLUSION: Our study suggests that CMV infection, total plasma cholesterol, decreased Qac, and nPCR are important risk factors of AVF failure in HD patients.

Urinary bladder injuries during vascular surgery.

Urologic complications related to vascular surgery involving the ureter have been well recognized. These include ureteral compression from aneurysms, congenital anomalies such as retrocaval ureter, obstruction from retroperitoneal fibrosis, iatrogenic injury, and ureteric fistulas. Complications involving the bladder are more infrequent. Most of these bladder-related complications involve the use of tunneling devices for synthetic bypass grafts. We report an unusual case of a transvesically placed femoral-femoral bypass graft with delayed presentation. We also reviewed the English literature for experience with diagnosis and treatment of bladder injuries during vascular surgical procedures.

Treatment of TIPS/biliary fistula-related endotipsitis with a covered stent.

"Infective endotipsitis" describes a recurrent bacteremia or fungemia in patients with a transjugular intrahepatic portosystemic shunt (TIPS) in place and no other identifiable source of infection. The present report describes a patient who developed polymicrobial endotipsitis 6 years after TIPS creation. Blood cultures remained positive for polymicrobial growth despite long courses of antibiotic therapy. Communication between the TIPS and an infected biliary tree, precipitated by cholecystitis, was ultimately recognized. The biliary/TIPS fistula was closed with a polytetrafluoroethylene-covered stent. The patient remains asymptomatic and follow-up blood cultures remain negative with a low dose of oral antibiotics 2 years after the procedure.

Infected pseudoaneurysm of the femoral artery secondary to melioidosis infection of a previous femoropopliteal bypass graft.

Infected arterial aneurysm or pseudoaneurysm caused by Burkholderia pseudomallei is very rare; a review of the literature reveals only five previously reported cases. We report the first case of melioidosis infection of a previous femoropopliteal bypass graft complicated by para-anastomotic pseudoaneurysm of the femoral artery successfully treated by surgical removal of the old graft and creation of a new, extraanatomic, external iliac-to-popliteal bypass graft.

Chlamydia pneumoniae in coronary bypass grafts of redo patients. The concept of the 'adventitial baseline infection'.

The pathogenic role of Chlamydia pneumoniae in late coronary bypass graft failure has not yet been extensively investigated. We examined failed and new arterial/venous bypass grafts using immunohistochemistry, polymerase chain reaction (PCR), and serology. Thirty-four long-term failed grafts and 28 new grafts were examined in 21 patients undergoing redo coronary artery bypass grafting (CABG). Immunohistochemically, 28 (82%) failed grafts were positive in the intimal-medial compartment, and 33 grafts (97%) were positive for C. pneumoniae in the adventitia. Thirteen (46%) and 27 (96%) new grafts showed infection in the intima-media and in the adventitia, respectively (p < 0.05). Immunohistochemically, the overall presence of C. pneumoniae in all vessels examined was 66% in the intima-media and 97% in the adventitia (p < 0.05). C. pneumoniae was detected by PCR in 19 (31%) of all the vessels examined. C. pneumoniae seems to be frequently present in grafts of patients considered for redo CABG in Hungary. The adventitia of both failed, and new grafts particularly often contained C. pneumoniae. The results suggest that there exists an adventitial baseline infection from which infection of the inner wall layers develops, depending on local microenvironmental conditions. This is the first study to evaluate chlamydial infection in arterial/venous coronary grafts by immunohistochemistry, PCR, and serology.

Seropositivity for Helicobacter pylori antibodies is associated with lower occurrence of venous bypass graft occlusion.

Common chronic infections including those caused by cytomegalovirus (CMV), herpes simplex viruses (HSV), Helicobacter pylori and Chlamydia pneumoniae have previously been related to increased risk of coronary heart disease (CHD). We investigated the association between serology of these chronic infections and coronary bypass graft occlusions in 61 patients. As a result, IgG seropositivity rate against H. pylori was higher among patients without occlusion (82%) than in those with occlusion (45%) or apparently healthy controls (57%) (p = 0.004 and p = 0.008, respectively). In conclusion, H. pylori infection, as judged by IgG seropositivity, is associated with lower occurrence of venous bypass graft occlusion in patients with CHD and may thus be connected with better outcome and prognosis of CHD patients after bypass graft surgery.

Infectious complications of old nonfunctioning arteriovenous grafts in renal transplant recipients: a case series.

Occult infection of old nonfunctioning arteriovenous grafts (AVGs) is frequent among hemodialysis patients. It is a risk factor for bacteremia and serious AVG-related infection. Immunocompromised patients are at increased risk of dissemination of occult AVG infection. We present a series of five renal transplant recipients who developed acute life-threatening infections that originated in their old nonfunctioning AVGs. Their presenting symptoms were noticeably varied. In two patients, infection of the AVG was characterized by local physical signs of infection around the AVG. In three patients, no physical signs of AVG infection were detected by physical examination. Among these, two presented with bacteremia, and one presented with failure to thrive. Detection of AVG infection in the absence of local signs of infection requires a high index of suspicion. Surgical resection and antimicrobial treatment led to a complete cure in four of these patients. One patient developed recurrent bacterial endocarditis and died. Old nonfunctioning AVGs are potential sources of serious infection in renal transplant recipients. Renal transplant recipients with old nonfunctioning AVGs who present with unexplained bacteremia, fever of unknown origin, or failure to thrive should be investigated for occult AVG infection. Screening for occult infection of the old nonfunctioning AVG may be considered before kidney transplantation, especially if the candidate gives a history of previous bacteremia or fever of unknown origin.

An unusual vascular graft infection by Aspergillus--a case report and literature review.

Vascular graft infection due to Aspergillus is a rare event. Only 11 previous case reports have been documented. All of these infections were in the aortic position, and infrainguinal arterial prosthetic graft involvement has been uncommon. The usual clinical presentation was back pain. Fever and systemic complaints were usually present. An unusual case that began with bilateral groin pain is reported and a review of the clinical presentation and the management of the other cases described in the literature is presented.

Detection of Chlamydia pneumoniae but not cytomegalovirus in occluded saphenous vein coronary artery bypass grafts.

BACKGROUND: A causal relation between atherosclerosis and chronic infection with Chlamydia pneumoniae and/or cytomegalovirus (CMV) has been suggested. Whether the unresolved problem of venous coronary artery bypass graft occlusion is related to infection with C pneumoniae and/or CMV has not been addressed. METHODS AND RESULTS: Thirty-eight occluded coronary artery vein grafts and 20 native saphenous veins were examined. Detection of C pneumoniae DNA was performed by use of nested polymerase chain reaction (PCR). Homogenisates from the specimen were cultured for identification of viable C pneumoniae. Both conventional PCR and quantitative PCR for detection of CMV DNA were applied. Differential pathological changes (degree of inflammation, smooth muscle cell proliferation [MIB-1]) were determined and correlated to the detection of both microorganisms. C pneumoniae DNA could be detected in 25% of occluded vein grafts. Viable C pneumoniae was recovered from 16% of occluded vein grafts. Except for 1 native saphenous vein, all control vessels were negative for both C pneumoniae detection and culture. All pathological and control specimens were negative for CMV DNA detection. Pathological changes did not correlate with C pneumoniae detection. CONCLUSIONS: Occluded aorto-coronary venous grafts harbor C pneumoniae but not CMV. The detection of C pneumoniae in occluded vein grafts warrants further investigation.