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.

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.

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.

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.

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.

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.

Specificity of detection of Chlamydia pneumoniae in cardiovascular atheroma: evaluation of the innocent bystander hypothesis

Chlamydia pneumoniae has been detected in atherosclerotic plaque, raising the question of whether this detection is specific to atheromatous tissue. To evaluate this question, we tested cardiovascular and non-cardiovascular tissue samples from 38 autopsy cases by polymerase chain reaction and immunocytochemistry. We also tested 33 granuloma biopsy specimens, as the organism has been detected in macrophages. C. pneumoniae was detected in coronary artery tissue from 13 (34%), lung from 5 (13%), liver from 4 (10%), and spleen from 2 (5%) of the 38 autopsy cases (P < 0.05 for comparison of proportion of positive coronary arteries with that of each of the other types of tissue). Of the 21 cases with at least one positive tissue sample, 11 had only a positive cardiovascular tissue (coronary artery, venous bypass graft, or myocardium), 7 had both cardiovascular and non-cardiovascular positive tissues, and 3 had only a non-cardiovascular positive tissue. C. pneumoniae was thus detected relatively infrequently in non-cardiovascular tissues, and its detection in these tissues was usually in association with its detection in cardiovascular tissue from the same patient. The organism was also infrequently detected in granulomatous tissue (3/33 specimens). These findings demonstrate that C. pneumoniae is more frequently found in atherosclerotic than normal tissue and support the hypothesis that C. pneumoniae has a role in the pathogenesis of atherosclerosis.

Surgical management of infrainguinal arterial prosthetic graft infections: review of a thirty-five-year experience

PURPOSE

The purpose was to determine the early and late mortality and morbidity rates associated with infrainguinal arterial prosthetic graft infection (IAPGI) and to identify optimal methods of management.

METHODS

The study included 53 men and 14 women (mean age, 61 years) in whom a total of 68 IAPGIs developed in the years 1959 to 1993. IAPGI involved 58 femoropopliteal grafts (85%), six femorodistal grafts (9%), and four other grafts or synthetic patches (6%). Graft material was dacron in 36 (53%), polytetrafluoroethylene in 28 (41%), and human umbilical vein in four (6%). Sixteen IAPGIs (24%) involved limbs that had required amputations before IAPGI was diagnosed. Twenty-six (38%) of the 68 grafts were thrombosed, and 14 (88%) of the 16 amputees had occluded grafts.

RESULTS

Staphylococcal organisms were isolated from 34 (58%) of the 59 IAPGIs for which culture data were available. The median intervals until IAPGI was diagnosed were 3 months after implantation and 1 month after the last procedure involving the original graft. Initial management consisted of local measures only in 13 (19%), partial removal or in situ graft replacement in 15 (22%), and total graft excision in 40 (59%). Total excision was performed in 15 (94%) of the 16 patients with prior amputations and in only 25 (48%) of the 52 intact limbs. The overall postoperative mortality rate was 18%; seven (58%) of the 12 early deaths were related to sepsis, and all 12 occurred within the group of 51 patients (24%) for whom limb salvage was still being attempted (p = 0.056). IAPGI ultimately led to amputations in 21 (40%) of 52 intact limbs within the first year. Twenty-three (82%) of the 28 IAPGIs managed with incomplete graft removal required subsequent operations for continued sepsis, compared with five (13%) of the 40 treated with complete excision (p < 0.001). The cumulative 5-year survival rate (77%) for 53 patients who survived operation was less than that (89%) for the normal, age-matched U.S. male population.

CONCLUSIONS

IAPGI is associated with substantial early mortality and amputation rates. Complete excision of infected graft material results in a significant reduction in the incidence of recurrent sepsis.

Culture of intraluminal thrombus during abdominal aortic aneurysm resection: significant contamination is rare

The significance of positive bacterial cultures from intraluminal thrombus in patients undergoing repair of abdominal aortic aneurysm remains controversial. Over the last 4 years, thrombus was cultured during aneurysm repair in 116 patients. All patients received cephalosporin antibiotic before and for 48 h after operation. Although none of the aneurysms appeared to be clinically infected, six patients (5.2%) had positive cultures. Four groups were identified based on the bacteria cultured: group I, coagulase-negative staphylococci, light growth (three patients); group II, coagulase-negative staphylococci, light growth and 'Streptococcus viridans' (one patient); group III, Bacillus sp., heavy growth (Gram-negative stain) (one patient); group IV, Clostridium perfringens, occasional growth (one patient). One of the six patients died during resection; the other five are alive without graft infection at 5-24 (mean 12) months after operation. The absence of graft infection suggests that positive cultures were not clinically significant or were adequately covered by the antibiotic prophylaxis. The incidence of positive cultures was lower than previously reported. Routine culture of aneurysm thrombus in the absence of clinical infection is probably not cost-effective.

Detection of cytomegalovirus in paraffin-embedded postmortem coronary artery specimens of heart transplant recipients by the polymerase chain reaction: implications of cytomegalovirus association with graft atherosclerosis

To assess the presence of cytomegalovirus in various tissues and its relevance to the development of graft atherosclerosis, 54 postmortem paraffin-embedded tissue samples from 15 heart transplant recipients who survived more than 100 days were analyzed by the polymerase chain reaction for cytomegalovirus. Eight patients had known previous cytomegalovirus exposure; 7 patients did not. Of the eight with known previous exposure, three patients (38%) died of graft atherosclerosis versus four (57%) of the seven patients without previous exposure. Of the 54 specimens, 49 were positive for beta-globin (inclusive positive control), including 38 coronary artery, five lung, five gastrointestinal, and one kidney. Only two coronary artery specimens were cytomegalovirus positive in a single patient with known cytomegalovirus exposure who did not have evidence of graft atherosclerosis at autopsy. Other tissues tested showed positive lung and stomach specimens in the patient with cytomegalovirus-positive coronary artery specimens and positive kidney, lung, and gastrointestinal specimens in a second patient. No specimens were cytomegalovirus positive in the remaining patients, despite the presence of graft atherosclerosis or previous cytomegalovirus exposure. Our data do not support the hypothesis that graft atherosclerosis is associated with latent cytomegalovirus infection of the coronary arteries. The role of cytomegalovirus in the pathogenesis of graft atherosclerosis is unknown, but possibly it represents a modulation of the immune system by remote infection.

Cytomegalovirus infection and accelerated cardiac allograft vasculopathy in human cardiac allografts

Cardiac allograft vasculopathy is a major limiting factor of the long-term survival of heart transplant patients. An association of cytomegalovirus infection and cardiac allograft vasculopathy has been described. We analyzed 104 endomyocardial biopsy specimens obtained from 53 heart transplant recipients and correlated the histologic findings with 115 angiograms obtained from the same patients during 4 postoperative years. The frequency of vascular changes in endomyocardial biopsy specimens was significantly higher than in angiograms during the first 3 posttransplantation years (P < 0.001, P < 0.005, P < 0.03, respectively). Also, in patients with angiographically documented cardiac allograft vasculopathy, significantly higher scores of capillary and arteriolar endothelial cell accumulation and arteriolar intimal thickness were recorded when compared with the recipients with normal angiograms (P < 0.02, P < 0.05, P < 0.005, respectively). Altogether, 29 of 53 recipients underwent cytomegalovirus infection during the first posttransplant year. Cytomegalovirus infection was associated with arteriolar endothelial cell accumulation and with increased intimal thickness of intramyocardial vessels of 1-year endomyocardial biopsy specimens when compared with cytomegalovirus-free recipients (P < 0.02 and P < 0.005, respectively). After the second year, the cytomegalovirus-associated endothelial cell response subsided, but the thickness of intima had increased when compared with cytomegalovirus-free patients (P < 0.05). Thereafter, the cytomegalovirus-associated histologic changes reached a plateau. In coronary angiography, the cardiac allograft vasculopathy changes were detected in a slower pace. Thus only after 2 posttransplantation years, cytomegalovirus-associated acceleration of cardiac allograft vasculopathy was observed, compared with cytomegalovirus-free patients (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The microbiology of explanted vascular prostheses

The incidence of bacterial colonization and the microflora of prosthetic vascular graft material explanted from 44 patients undergoing graft revision was determined. Graft material for culture was obtained from aortofemoral or femoropopliteal vascular prostheses without signs of infection but requiring revision for femoral anastomotic aneurysm (n = 21) or thrombosis (n = 26). Explanted graft material was placed in tryptic soy broth and ultrasonically oscillated to disrupt the adherent graft surface biofilm, which is a technique that increases the recovery of microorganisms compared with standard microbiologic culture methods. Microorganisms were isolated from 90% (19/21) of grafts associated with anastomotic aneurysms and 69% (18/26) of thrombosed grafts. Staphylococcus epidermidis was the prevalent organism recovered and accounted for 69% of the isolates. Slime production, a growth characteristic of S. epidermidis associated with prosthetic device infection in humans, was demonstrated by 87% (13/15) of strains isolated from grafts with pseudoaneurysms compared with 33% (4/12) of strains isolated from occluded grafts (p less than 0.01). Despite the high incidence (79%) of colonization of vascular prostheses, no patient developed wound or graft infection after graft replacement and perioperative antibiotic administration. Low-virulent microorganisms, such as S. epidermidis, can colonize vascular prostheses and not provoke signs of graft infection. The high recovery rate of slime-producing S. epidermidis strains from grafts with anastomotic aneurysms and the adherence-mediated growth of these bacteria on biomaterials suggest this late graft complication is the sequelae of a bacteria-laden biofilm infection.

Bacterial adherence to endothelial-seeded polytetrafluoroethylene grafts

Since infections of an arterial prosthesis pose a serious threat to life and limb, efforts to produce a graft that is resistant to hematogenous bacteremia continue. We studied the effect of endothelial seeding on bacterial adherence to polytetrafluoroethylene grafts in a canine model. Enzymatically derived venous endothelial cells were seeded in 10 cm long, 4 mm inner diameter polytetrafluoroethylene grafts, which were then implanted as carotid interpositions opposite contralateral unseeded controls. After 4 to 8 weeks, each dog received an intravenous infusion of 3 X 10(8) radiolabeled Staphylococcus aureus. Seeded grafts had significantly fewer adherent viable bacteria than had control grafts (mean, 432 versus 989; p less than 0.05) and significantly fewer radiolabeled bacteria (mean, 2 X 10(5) versus 8 X 10(5); p less than 0.05). Seeded grafts also had significantly more thrombus-free, luminal surface area than had control grafts (mean, 72% versus 40.6%; p less than 0.05). Scanning electron microscopy and autoradiography of seeded grafts confirmed that the sites of bacterial adherence largely corresponded to accumulations of surface thrombus. In this experiment, endothelial seeding appeared to protect against bacterial adherence after a hematogenous challenge 4 to 8 weeks after implantation by reducing luminal thrombi.