Prevention of graft infection by bonding of gentamycin to Dacron prostheses.

To increase the efficacy of perioperative antibiotic prophylaxis in vascular surgery an experimental study including topical application of the gentamicin derivative EMD 46/217 and fibrin sealant as antibiotic carrier to Dacron prostheses was initiated. In vitro treatment of Dacron with gentamicin and fibrin was followed by constant antibiotic release for 3 weeks. In a subsequent animal study Dacron grafts were implanted in the aorta of 10 pigs after direct contamination with Staphylococcus aureus solution. One graft was pretreated with the antibiotic/fibrin compound, a second with the antibiotic alone. Grafts 3 (no pretreatment) and 4 (fibrin alone) served as controls. After 1 week the grafts and their corresponding implantation sites were excised for measurement of antibiotic content and for culture. The antibiotic content of grafts with the antibiotic/fibrin compound was 25.0 +/- 7.2 micrograms/gm wet weight, whereas Dacron pretreated with the antibiotic alone contained no measurable drug amounts except for one specimen (0.5 microgram/gm) (antibiotic/fibrin vs antibiotic, p less than .0005). The corresponding implantation sites to antibiotic/fibrin grafts contained 1.07 +/- 0.54 microgram/gm antibiotic, whereas in only 2/10 implantation sites of antibiotic grafts low antibiotic levels were found (0.05 and 0.2 microgram/gm) (antibiotic/fibrin vs antibiotic, p less than 0.005). All control grafts and 9/10 antibiotic grafts were infected. By contrast, only five were contaminated, and 5 of 10 remained sterile after culture (antibiotic/fibrin vs antibiotic, p less than 0.05). This finding correlates with the antibiotic content in the Dacron. It is concluded that pretreatment of prosthetic Dacron grafts with the antibiotic/fibrin compound results in binding of sufficient amounts of antibiotic for at least 1 week.(ABSTRACT TRUNCATED AT 250 WORDS)     

An in vitro study of the properties influencing Staphylococcus epidermidis adhesion to prosthetic vascular graft materials.

This study examines the influence of the properties of various vascular graft materials on the bacterial adherence process of two different strains of Staphylococcus epidermidis (mucous and normucous producing). Dacron grafts (both knitted and woven), Teflon grafts, and Dacron grafts coated with one and two layers of silicone were studied because these materials differ significantly in porosity, hydrophobicity, and surface charge (zeta potential). Graft segments were immersed in 3H-labeled bacteria solution for periods ranging from 5 to 180 minutes and liquid scintillation techniques were used to quantify bacterial adherence. The porous knitted Dacron material had a significantly higher rate of bacterial adherence than either the woven Dacron or Teflon (p less than 0.05). Silicone coating (either one or two layers) reduced adherence by a factor of four for the knitted Dacron (p less than 0.05) and by a factor of two for woven Dacron (p less than 0.05). The mucous producing strain of S. epidermidis displayed significantly better adherence to woven and knitted Dacron than the normucous producing strain, but only when 0.25% dextrose was added to the bacteria solution. These findings indicate that the highly porous knitted Dacron grafts have the highest propensity for bacterial adhesion. Graft materials with the most negative zeta potentials are more resistant to bacterial adherence. Silicone coating of Dacron material significantly changed adherence characteristics, suggesting that this may be a viable strategy for protecting implantable medical devices containing materials to which bacteria readily adhere.     

Comparison of different vascular prostheses and matrices in relation to endothelial seeding.

Thin-walled expanded polytetrafluoroethylene (ePTFE), woven Dacron and gelatin-impregnated Dacron (Gelseal) vascular grafts were compared, the grafts being coated with three different matrices: collagen IV, fibronectin and preclot matrix. In addition, untreated ePTFE and Gelseal were examined. The graft segments, coated with these matrices, were incubated with radiolabelled adult human endothelial cells for 30, 60 and 90 min. Endothelial cell adherence was calculated from the ratio of radioactive counts in the grafts to counts in grafts plus supernatants. Endothelial cell attachment to untreated grafts was poor, but a suitable matrix significantly improved adherence. All three matrices tested gave good results, although preclot was best; 30-60 min incubation was sufficient for optimum cell attachment. Cell adherence to both Dacron and ePTFE was significantly better than to Gelseal. The type of prosthetic polymer and the substrate protein coating used to promote endothelial cell adherence are two important factors which may determine the ultimate success of endothelial seeding in the operating room.     

Optimization of rifampin coating on covered Dacron endovascular stent grafts for infected aortic aneurysms

Objective

In the treatment of an infected aorta, open repair and replacement with a rifampin-impregnated Dacron vascular graft decrease the risk of prosthetic graft infections, with several protocols available in the literature. We hypothesize that the same holds true for endovascular aneurysm repair, and after studying and optimizing rifampin solution concentration and incubation period to maximize the coating process of rifampin on Dacron endovascular stent grafts (ESGs), we propose a rapid real-time perioperative protocol.

Nonthrombogenic Polymer Vascular Prosthesis

Abstract: Although many synthetic vascular grafts have been developed and evaluated experimentally or clinically, none of them have met long-term patency when applied as a small diameter vascular substitute. We have recently developed a small caliber vascular graft (3 mm i.d.) using a nonthrombogenic polymer coating. The graft consists of three layered structures: Dacron for the outer layer, polyurethane in the middle layer, and a HEMA/ styrene block copolymer (HEMA-st) coating for the inner layer. HEMA-st is an amphiphilic block copolymer composed of 2-hydroxyethyl methacrylate and styrene which has demonstrated improved blood compatibility over existing biomedical polymers in both in vitro and ex vivo experiments. Ten grafts were evaluated in a dog bilateral carotid replacement model. The grafts were electively retrieved at 7, 14, 30, 92, and 372 days after implantation.
All grafts were patent without detectable thrombi along the graft length including anastomotic sites. Scanning electron micrographs of retrieved graft lumen showed fairly clean surfaces covered with a homogenous protein-like layer without microthrombi or endothelial cell lining. The thickness of the surface protein layer measured by a transmission electron microscopy was what can be described as monolayer protein adsorption regardless of implantation periods of as much as 372 days. A stable monolayer adsorbed protein layer formed on HEMA-st surfaces demonstrated nonthrombogenic activities in vivo and secure long-term patency of small caliber vascular grafts with the absence of an endothelial cell lining.     

Reduction of platelet deposition on vascular grafts using an antiplatelet graft coating technique

The systemic use of platelet inhibitors has been shown to improve vascular graft function. In this study a biodegradable coating of polymeric polylactic acid (PLA) containing a microparticulate suspension of aspirin (ASA) 30% by weight, was applied to the lumenal surface of small diameter vascular prostheses to reduce platelet deposition on canine implanted arterial grafts. USCI 4-mm ID Dacron internal velour grafts were used. Coated and contralateral noncoated (control) prostheses were implanted in canine carotid and femoral arteries. Graft performance was assessed by determination of aspirin elution rates, in vivo red cell subtracted 111indium-labeled platelet scans, and post implant platelet aggregation studies. Eighty percent of the aspirin in the coated grafts was released during the first 24 hr of perfusion and approximately 20% of the aspirin remained in grafts after 1 month. In vivo platelet scans documented less platelet deposition on ASA-coated grafts when compared to controls 2 and 24 hr post implant (P less than 0.01, P less than 0.05, respectively). There was no significant difference in platelet deposition on ASA-coated and control grafts at 2 weeks or 1 month post implant. Post implant platelet aggregation studies indicated systemic platelet inhibition for 4-5 days. It was concluded that aspirin incorporation in a polylactic acid coating applied to 4-mm ID vascular prostheses reduced the platelet affinity of Dacron grafts and exerted a temporary local and systemic platelet inhibiting effect.     

Adsorption of Basic Fibroblast Growth Factor onto Dacron Vascular Prosthesis and Its Biological Efficacy

Abstract: Adsorption of basic fibroblast growth factor (bFGF) onto a plain fabric Dacron vascular prosthesis (Micron, Intervascular Co., Ltd., Clearwater, FL, U.S.A.) and its release properties from the graft were examined using labeled bFGF, and its biological efficacy was evaluated in an animal study. In an in vitro study, 6 pieces of a Dacron graft were soaked in [¹²⁵I]-bFGF solution for 30 min. Then these pieces were soaked in 500 ml saline solution for 15 days, and the radioactivity of each piece was counted at various times. The initial amount of adsorbed bFGF was 2.48 ng/cm². At 24 h, 41% of the adsorbed bFGF was released and 59% remained. On the third day 55% remained, on the seventh day 52%, and on the 15th day 50% remained on the Dacron surface. Using the atmospheric glow discharge (APG) plasma treatment to render hydrophilic properties, no significant difference between plasma-treated grafts and non-plasma-treated grafts regarding the adsorption of bFGF was observed. In an in vivo study, 6 Dacron pieces adsorbed with bFGF were implanted in the subcutaneous layer of 2 dogs and removed 5 days after implantation. Six Dacron pieces without bFGF were also implanted as a control into the 2 dogs. Fibroblast migration with capillary ingrowth was observed in the specimens with bFGF compared to the controls. These results indicate that the simple adsorption of bFGF onto Dacron fabric is a useful method for the acceleration of host cell migration and capillary ingrowth into Dacron fabric vascular prostheses.     

Simple methods for direct antibiotic protection of synthetic vascular grafts

Two simple methods for direct antibacterial protection of synthetic vascular grafts were investigated. In the first protocol the highly protein-bound antibiotics nafcillin (90% protein bound), cefazolin (80%), and cefamandole (70%) were added directly to preclotting blood. Knitted Dacron grafts preclotted in the presence of one of these drugs absorbed significant amounts. Although at high concentrations these antibiotics exhibited anticoagulant effects, significant antibacterial protection was obtained at lower antibiotic levels. Washing treated grafts for 6 hours failed to eliminate the antibacterial activity. Antibiotics remained on the grafts for at least 96 hours. In the second protocol knitted Dacron grafts were soaked in a suspension of silver-pefloxacin, a silver-nalidixic acid analogue with intense antistaphylococcic activity. Using 110Ag-labeled complexes, significant antibiotic activity was documented on the graft after 19 days of washing. Four nafcillin-treated prostheses, six silver-pefloxacin-coated grafts, and 11 control grafts were interposed in the infrarenal aorta of dogs and immediately challenged with an intravenous infusion of 1 X 10(7) Staphylococcus aureus. None of the four nafcillin-treated grafts was infected at 3 weeks. One of the six silver-pefloxacin-coated grafts grew staphylococci, and 9 of 11 controls had positive graft cultures for Staphylococcus when harvested. These studies suggest that prosthetic grafts can be simply coated at the time of implantation with antibiotics selected for appropriate binding and antibacterial characteristics to obtain an infection-resistant prosthesis.     

Effect on infection resistance of a local antiseptic and antibiotic coating on osteosynthesis implants: an in vitro and in vivo study.

The purpose of this study was to acquire information about the effect of an antibacterial and biodegradable poly-L-lactide (PLLA) coated titanium plate osteosynthesis on local infection resistance. For our in vitro and in vivo experiments, we used six-hole AO DC minifragment titanium plates. The implants were coated with biodegradable, semiamorphous PLLA (coating about 30 microm thick). This acted as a carrier substance to which either antibiotics or antiseptics were added. The antibiotic we applied was a combination of Rifampicin and fusidic acid; the antiseptic was a combination of Octenidin and Irgasan. This produced the following groups: Group I: six-hole AO DC minifragment titanium plate without PLLA; Group II: six-hole AO DC minifragment titanium plate with PLLA without antibiotics/antiseptics; Group III: six-hole AO DC minifragment titanium plate with PLLA + 3% Rifampicin and 7% fusidic acid; Group IV: six-hole AO DC minifragment titanium plate with PLLA + 2% Octenidin and 8% Irgasan. In vitro, we investigated the degradation and the release of the PLLA coating over a period of 6 weeks, the bactericidal efficacy of antibiotics/antiseptics after their release from the coating and the bacterial adhesion of Staphylococcus aureus to the implants. In vivo, we compared the infection rates in white New Zealand rabbits after titanium plate osteosynthesis of the tibia with or without antibacterial coating after local percutaneous bacterial inoculations at different concentrations (2 x 10(5)-2 x 10(8)): The plate, the contaminated soft tissues and the underlying bone were removed under sterile conditions after 28 days and quantitatively evaluated for bacterial growth. A stepwise experimental design with an "up-and-down" dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher exact test (p < 0.05). Over a period of 6 weeks, a continuous degradation of the PLLA coating of 13%, on average, was seen in vitro in 0.9% NaCl solution. The elution tests on titanium implants with antibiotic or antiseptic coatings produced average release values of 60% of the incorporated antibiotic or 62% of the incorporated antiseptic within the first 60 min. This was followed by a much slower, but nevertheless continuous, release of the incorporated antibiotic and antiseptic over days and weeks. At the end of the test period of 42 days, 20% of the incorporated antibiotic and 15% of the incorporated antiseptic had not yet been released from the coating. The antibacterial effect of the antibiotic/antiseptic is not lost by integrating it into the PLLA coating. The overall infection rate in the in vivo investigation was 50%. For Groups I and II the infection rate was both 83% (10 of 12 animals). In Groups III and IV with antibacterial coating, the infection rate was both 17% (2 of 12 animals). The ID50 in the antibacterial coated Groups III and IV was recorded as 1 x 10(8) CFU, whereas the ID50 values in the Groups I and II without antibacterial coating were a hundred times lower at 1 x 10(6) CFU, respectively. The difference between the groups with and without antibacterial coating was statistically significant (p = 0.033). Using an antibacterial biodegradable PLLA coating on titanium plates, a significant reduction of infection rate in an in vitro and in vivo investigation could be demonstrated. For the first time, to our knowledge, we were able to show, under standardized and reproducible conditions, that an antiseptic coating leads to the same reduction in infection rate as an antibiotic coating. Taking the problem of antibiotic-induced bacterial resistance into consideration, we thus regard the antiseptic coating, which shows the same level of effectiveness, as advantageous.     

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)     

Fluoropolymer-coated dacron versus PTFE grafts for femorofemoral crossover bypass: randomised trial.

OBJECTIVES: To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery. DESIGN: A randomised multicentre clinical trial comparing two vascular grafts with participation of 10 departments of vascular surgery in Denmark, Sweden and Norway. PATIENTS AND METHODS: 198 patients were randomised to PTFE (n=107) or fluoropolymer-coated Dacron grafts (n=91), 63% underwent surgery for claudication, 27% for ischaemic rest pain and 10% for tissue loss. The median follow-up time was 24 months (IQR 19-26 months). RESULTS: The primary patency rate of the two grafts was similar (log rank test: p=0.35). The primary patency rates (95% CI) for coated Dacron and PTFE grafts were 92% (86-98) and 94% (89-99) at 12 months and 87% (74-95) and 93% (87-99) at 24 months, respectively. CONCLUSION: In patients with unilateral iliac artery disease not amenable to angioplasty, the femoral-femoral bypass is durable and effective. No difference in patency was found between the two graft materials (fluoropolymer coated Dacron and PTFE).     

Efficacy of vancomycin, teicoplanin and fusidic acid as prophylactic agents in prevention of vascular graft infection: an experimental study in rat.

OBJECTIVES: To compare the efficacy of a single prophylactic dose of intra-peritoneal vancomycin and teicoplanin with anti-biotic treated Dacron grafts (vancomycin, teicoplanin, 10 or 40% fusidic acid-soaked grafts) in preventing vascular graft infections in a rat model. DESIGN: Prospective, randomized, controlled animal study. MATERIALS AND METHODS: The graft infections were established in the subcutaneous tissues of 80 female Sprague-Dawley rats by the implantation of Dacron prostheses followed by the topical inoculation with methicillin-resistant Staphylococcus aureus. The study groups were as follows: (1) uncontaminated control group, (2) untreated contaminated group, (3) contaminated group with intra-peritoneal vancomycin, (4) contaminated group with intra-peritoneal teicoplanin, (5) contaminated group received vancomycin-soaked Dacron graft, (6) contaminated group received teicoplanin-soaked Dacron graft, (7) contaminated group received 40% fusidic acid-soaked Dacron graft, and (8) contaminated group received 10% fusidic acid-soaked Dacron graft prophylaxis. The grafts were removed after 7 days and evaluated by a quantitative culture analysis. RESULTS: No infection was detected in controls. The untreated contaminated group had a high bacteria count (6.0 x 10(4) CFU/cm2 Dacron graft). Groups that received intra-peritoneal vancomycin or teicoplanin had less bacterial growth (4.8 x 10(3) and 3.9 x 10(3)CFU/cm2 Dacron graft, respectively). Similarly, the group that received 10% fusidic acid-soaked graft showed less bacterial growth (3.6 x 10(3) CFU/cm2 Dacron graft). The groups with vancomycin-, teicoplanin- and 40% fusidic acid-soaked grafts showed no evidence of infection. Statistical analyses demonstrated that intra-peritoneal prophylactic antibiotic treatment was less effective in inhibiting bacterial growth than high concentration antimicrobial-soaking of grafts. CONCLUSION: The use of vancomycin-, teicoplanin- and 40% fusidic acid-soaked grafts was effective in preventing primary prosthetic vascular graft infection.     

Experimental examination concerning the efficacy of silver-coated Dacron prostheses in vascular graft infections following subcutaneous implantation in a standardized infection model

It was the aim of the study to examine the efficacy of silver coated prostheses in comparison to Rifampin in impregnated prostheses in the prevention of vascular graft infections. MATERIAL AND METHODS: 24 C3H/HcN mice with a bodyweight between 24 and 27 grams were assigned to four different groups. GROUP I: control gel-sealed Dacron graft (Uni-Graft DV) (6), GROUP II: gel-sealed Dacron graft (Uni-Graft DV) contaminated locally with 2 x 10(7) CFU/1.2 ml Staphylococcus aureus ATCC 25923 (6), GROUP III: silver prosthesis (Intergard Silver) contaminated locally with 2 x 10(7) CFU/0.2 ml Staphylococcus aureus ATCC 25923 (6), GROUP IV: Rifampin impregnated prosthesis contaminated locally with 2 x 10(7) CFU/0.2 ml Staphylococcus aureus ATCC 25923 (6). 14 days after primary operation all animals were euthanized and the grafts harvested. Specimens were examined for signs of infections by histology and microbiology. RESULTS: At termination of the trial on day 14 none of the grafts of group I were contaminated. 6 out of 6 grafts in group II, 6 out of 6 grafts in group III and 1 out of 6 grafts in group IV presented with infected grafts. The use of antimicrobial Rifampin could significantly prevent infection after bacterial challenge in group IV. CONCLUSION: The silver protected prosthesis (Intergard Silver) seems to be not effective in protecting vascular infection in vivo. However, the Rifampin group showed excellent results. In conclusion Rifampin bonded gelatin-sealed Dacron grafts are significantly more resistant to bacteremic infection than are silver/collagen-coated Dacron grafts.     

Anastomotic tensile strength following in situ replacement of an infected abdominal aortic graft

The tensile strength and histologic features of anastomotic bonding were studied prior to and following in situ replacement of aortic vascular prostheses infected by Staphylococcus epidermidis. Sterile (n = 6) and infected (n = 19) Dacron grafts were used to replace the abdominal aorta of 25 dogs. After five weeks, grafts were explanted, and peak tensile force (measured in kilograms) required for anastomotic disruption was measured using a linear gain tensiometer. Anastomotic tensile strength (mean +/- SEM) of infected grafts (5.4 +/- 0.5 kg) was decreased when compared with that of sterile, control grafts (9.0 +/- 0.9 kg). The decreased anastomotic tensile strength of infected grafts was the result of an inflammatory aortitis adjacent to the suture line. Only grafts infected with the study strain of bacteria demonstrated signs of infection. In 19 dogs, the graft infection was treated by graft excision, antibiotic administration, and in situ graft replacement (Dacron or polytetrafluoroethylene prostheses). After five weeks and 12 weeks, anastomotic tensile strength of polytetrafluoroethylene (10.6 +/- 0.6 kg) and Dacron (10.8 +/- 0.5 kg) replacement grafts was similar to that of uninfected control grafts. In situ replacement of vascular prostheses infected by S epidermidis can result in graft healing with normal anastomotic bonding.     

The prophylactic efficacy of rifampicin-soaked graft in combination with systemic vancomycin in the prevention of prosthetic vascular graft infection: an experimental study

OBJECTIVE: To investigate the prophylactic efficacy of systemic, topical, or combined antibiotic usage in the prevention of late prosthetic vascular graft infection caused by methicillin-resistant Staphylococcus epidermidis (MRSE) and the differential adherence of S. epidermidis to Dacron and ePTFE grafts in a rat model. MATERIALS AND METHODS: Graft infections were established in the back subcutaneous tissue of 120 adult male Wistar rats by implantation of 1-cm(2) Dacron/ePTFE prosthesis followed by topical inoculation with 2 x 10(7) CFU of clinical isolate of MRSE. Each of the series included one group with no graft contamination and no antibiotic prophylaxis (uncontaminated control), one contaminated group that did not receive any antibiotic prophylaxis (untreated control), one contaminated group in which perioperative intraperitoneal prophylaxis with vancomycin (10 mg/kg) was administered, two contaminated groups that received rifampicin-soaked (5 mg/1 ml) or vancomycin-soaked (1 mg/1 ml) grafts, and one contaminated group that received a combination of rifampicin-soaked (5 mg/1 ml) graft with perioperative intraperitoneal vancomycin prophylaxis (10 mg/kg). The grafts were removed sterilely 7 days after implantation and evaluated by using sonication and quantitative blood agar culture. RESULTS: MRSE had significantly greater adherence to Dacron than ePTFE grafts in the untreated contaminated groups (P < 0.001). Rifampicin had better efficacy than vancomycin in topical application, but the difference was not statistically significant (P > 0.05). Intraperitoneal vancomycin showed a significantly higher efficacy than topical vancomycin or rifampicin (P < 0.001). The best results were provided by a combination of intraperitoneal vancomycin in rifampicin-soaked graft groups (P < 0.001). CONCLUSIONS: The combination of rifampicin and intraperitoneal vancomycin seems to be the best choice for the prophylaxis of late prosthetic vascular graft infections caused by MRSE.     

Efficacy and duration of antistaphylococcal activity comparing three antibiotics bonded to Dacron vascular grafts with a collagen release system.

Type 1 collagen, minimally cross-linked, was used to bind one of three antibiotics (amikacin, chloramphenicol, or rifampin) to double-velour Dacron grafts to develop a prosthesis resistant to infection. Six millimeter disks of graft were placed in separate flasks (specific for each antibiotic) containing albumin in saline and continuously agitated. At daily intervals the solution was changed, and paired graft samples were removed and placed on a blood agar plate confluently streaked with bacteria. The initial zone of inhibition (centimeters squared), the time to 50% reduction of initial inhibition zone, and the overall duration of antibacterial activity were recorded on an exponential model. Grafts bonded with amikacin and chloramphenicol had an overall duration of activity of only 2 and 1 day, respectively, against Staphylococcus aureus. The collagen bonded rifampin grafts had an initial zone of 14.76 cm,2 took 3.92 days to reach 50% of initial inhibition, and had an overall duration of activity of 22.4 days. This was significantly better than grafts preclotted with 1.0 ml of rifampin (60 mg/ml) and 9 ml of blood (10.92 cm,2 1.06 days, and 5.6 days). When tested against a slime-producing Staphylococcus epidermidis (American Type Culture Collection No. 35983), the graft bonded with rifampin had inhibitory activity of up to 27.77 days with a 50% of activity eluted at 4.78 days, significantly better than the preclotted rifampin graft without collagen bonding. These data suggest that rifampin bonded by collagen can protect a vascular graft against infection from S. aureus and S. epidermidis for up to 3 weeks after implantation.     

Prevention of graft infection by use of prostheses bonded with a rifampin/collagen release system.

The objective of this study was to test the efficacy of bonding rifampin to double-velour Dacron grafts with collagen to prevent graft sepsis. Fifty 6.0 mm Dacron grafts (length 5.0 cm) impregnated with either collagen (control) or collagen plus rifampin (experimental) were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into four groups (each with an experimental and control subdivision) as a function of time between grafting and bacterial challenge. At 2, 7, 10, or 12 days after graft implantation, sequential groups were challenged with 1.2 x 10(8) colony forming units of Staphylococcus aureus (clinical isolate) intravenously suspended in 250 ml normal saline. Three weeks after hematogenous seeding, the grafts were sterilely harvested. One-tailed Fisher's exact test was used to compare the patency and culture-proven infection of control and antibiotic coated grafts as a function of implantation time before bacteremic challenge. In the 2-day group, four of six control grafts were infected compared with zero of six experimental grafts (p less than 0.030). In the 7-day group, five of six control grafts were infected with S. aureus versus zero of six in the experimental group (p less than 0.008). In the 10-day group, one of six experimental grafts was infected, but the control group had only two of six graft infections. In the 12-day group two of six experimental grafts and one of five control grafts were infected. These results indicate that rifampin bonded with collagen to knitted Dacron grafts will protect the graft from bacteremic infection for 7 days after implantation in a highly challenging model.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heat-denatured albumin-coated Dacron vascular grafts: physical characteristics and in vivo performance

Dacron fabrics with a wide range of porosities were autoclaved for 3 minutes after being soaked in serum, 5% albumin, or 25% albumin. Porosity of compound Dacron grafts made with 25% albumin was less than 1 ml/min/cm2 regardless of the fabric base, whereas porosity of grafts made with serum or 5% albumin was proportional to the porosity of the base fabric. Porosity of the compound grafts remained stable for more than 48 hours and to pressure greater than 450 mm Hg, if the grafts were kept moist. Tubes of Marlex mesh coated with heat-denatured albumin, implanted as infrarenal aortic replacements in dogs, showed complete albumin absorption by 3 weeks. However, perigraft tissue reaction and graft incorporation were minimal and extensive false aneurysm formation resulted. Knitted filamentous Dacron 6 mm tubes coated with heat-denatured albumin were implanted as iliofemoral bypass grafts in 12 dogs, with blood-preclotted knitted filamentous Dacron grafts implanted as contralateral control grafts. Comparison of the albumin-coated grafts with the blood-preclotted control grafts showed no differences in healing or patency at 4 to 6 months. Heat-denatured 25% albumin forms a strong and hemostatic coating regardless of fabric base. Albumin-Dacron compound grafts are easily and rapidly made in the operating room, handle well, and are suitable for large and medium-sized arterial replacements without changes in healing or patency. Because of slow tissue incorporation, however, albumin-coated knitted Dacron grafts should be avoided in patients who require long-term anticoagulation therapy.     

Complete in vitro prosthesis endothelialization induced by artificial extracellular matrix.

This report presents our research on the conditions necessary to substain optimal in vitro prosthetic endothelialization using human endothelium cultures. Human vein endothelial cells were seeded at a concentration of 3 x 10(5)/cm2 in a gelatinized Dacron patch graft coated with a commercial collagen film, using a solution of fibrin glue. Endothelium adhesion, proliferation, and survival were measured by [3H]thymidine incorporation, after 7 days of incubation. Finally, the morphology of prosthetic endothelialization was analyzed by scanning electron microscopy. We observed that the Dacron patch grafts coated with collagen film were able to promote endothelialization better than the prostheses coated with highly concentrated collagen solution or gelatin. We therefore concluded that the collagen film that supports endothelial cell adhesion and proliferation uniformly covers the entire synthetic endoluminal surface of the Dacron graft, thus preventing endothelial cell alterations induced by direct contact with the synthetic prosthetic surface.     

Utility of Polyethylene Terephthalate (Dacron) Vascular Grafts for Venous Outflow Reconstruction in Living-Donor Liver Transplantations

BackgroundVenous outflow reconstruction of modified right-lobe liver grafts has been shown to prevent the occurrence of graft congestion and subsequent complications, including graft loss. In the present study, we aimed to investigate the safety and efficacy of Dacron grafts for venous reconstruction in living donor liver transplantation (LDLT).MethodsBetween January 2016 and January 2018, Dacron grafts were used in 148 liver transplants. Of these, 104 patients who had a follow-up computerized tomography (CT) scan were enrolled into the study. A total of 179 outflow hepatic veins including V5, V8, partial middle hepatic vein, and accessory inferior right hepatic veins (IRHV) were reconstructed using synthetic Dacron grafts. Graft patency was evaluated with both intraoperative Doppler ultrasonography following reconstruction, and a follow-up CT was performed on the postoperative day 7 (±1). Retrospective data collection included demographics, parameters for small-for-size (laboratory tests [bilirubin, International Normalized Ratio] and ascites) syndrome, postoperative morbidity, and mortality.ResultsFollow-up CT revealed graft patency in 155 out of 179 (86.6%) vascular grafts. Postoperative seventh-day patency rates for each reconstructed vein were as follows: V5, 87.5% (70/80); V8, 87.7% (50/57); partial middle hepatic vein, 100% (11/11); and IRHV, 77.4% (24/31). No major graft-related complications (early graft dysfunction, graft infection) or graft-related mortality were observed. None of the recipients developed small-for-size syndrome based on laboratory tests and clinical findings.ConclusionsDacron vascular grafts appear as an advantageous and useful alternative for venous outflow reconstruction in LDLT.