Prevention Of Graft Infection Research Articles

Systemic and Local Antibiotic Prophylaxis in the Prevention of Prosthetic Vascular Graft Infection: an Experimental Study

Aim: to determine if local, in addition to systemic antibiotic prophylaxis (compared to that provided by systemic prophylaxis alone) provides additional benefit in terms of reducing graft infection. Methods: gelatin-sealed Dacron grafts were interposed in the infrarenal aorta of 36 mongrels and inoculated with 1 ml of a S. aureus suspension. Group 1 (control group) received no prophylaxis and were inoculated with 1 ml containing 109cfu/ml. Group 2 (n=6) received systemic prophylaxis (1 g cephamandole) and were inoculated with 105 cfu/ml (n=3) or 107 cfu/ml (n=3). Group 3 received systemic prophylaxis (1 g cephamandole) and were inoculated with 109 cfu/ml. Group 4 received systemic prophylaxis (2 g cephamandole) and were inoculated with 109cfu/ml. In group 5 and 6 grafts were soaked in a rifampicin solution before use and inoculated with 109 cfu/ml. Group 5 received no systemic prophylaxis and group 6 received systemic prophylaxis (1 g cephamandole). Grafts were harvested at 2 weeks, and peritonitis, perigraft abscess, anastomotic disruption and graft occlusion recorded. Swabs were taken of the graft, the perigraft tissues and the peritoneal fluid. Graft segments were incubated in broth medium. Results: inoculation with 109 cfu/ml ensured graft infection. Sytemic or local prophylaxis alone failed to prevent graft infection. Only systemic and local antibiotic prophylaxis provided significant better results than no prophylaxis at all (p<0.01) and local prophylaxis alone (p<0.05). However, total “graft sterility” was not achieved as bacteriologic analysis of the graft segments showed low bacterial counts (<10 bacteria/graft) in 5 of 6 grafts. Conclusion: local and systemic prophylaxis provided more protection as demonstrated by the significant decrease in the incidence of “overt” graft infection. Total “graft sterility” cannot be expected in the case of an overwhelming bacterial challenge.

Elution of Vancomycin and Tobramycin Bonded to Vascular Grafts

The elution of vancomycin and tobramycin from vascular grafts sealed with collagen and human blood was studied in vitro. The release of antibiotics was measured in three different types of soaked grafts, including grafts soaked with antibiotic after being sealed with albumin, those sealed with antibiotic and albumin mixture and those impregnated with fresh blood and antibiotic mixture. Each antibiotic was tested at two different concentrations, i.e. 5 mg/ml and 10 mg/ml for vancomycin and 2 mg/ml and 5 mg/ml for tobramycin. The eluted antibiotic concentrations were determined by the fluorescence polarization immunoassay. Initially large quantities of antibiotics were quickly eluted, depending on the amount of antibiotic mixture. A measurable amount of vancomycin was released for 3 days. There was no difference between the elution kinetics of the two antibiotics from the three different soaked grafts (p>0.05). Antibiotic-soaked grafts provided zones of inhibition against Staphylococcus aureus on Trypticase soy agar plate for up to 24 h.These results suggest that local application for 24 h of vancomycin or tobramycin with vascular grafts may be effective to prevent graft infection as shown by the fluorescence polarization immunoassay.

ONE-STAGE OPERATION FOR CONCOMITANT ABDOMINAL AORTIC ANEURYSM AND ADVANCED COLONIC CANCER -A CASE STUDY-

One-stage operation was carried out for concomitant infrarenal abdominal aortic aneurysm and an advanced cancer of the sigmoid colon. Since this patient also has a recurrence of lung cancer, one-stage operation was necessary to avoid loosing the chance for lung operation. In this case, resection and grafting of the aneurysm preceded left hemicolectomy. The colon was prepared preopertively, and the retroperitoneum was closed densely and wrapped with gauze to prevent graft infection. To protect the operation field from intestinal fluid and intestinal mucosa, a gastro-intestinal autosuture device (GIA) was used for resection of the colon. The postoperative course was uneventful without graft infection. Our result suggests that the one-stage operation is possible for concomitant abdominal aortic aneurysm and advanced colonic cancer in the same opertive field under a careful attention to prevent graft infection.

Local Application of Vancomycin for Prophylaxis of Graft Infection: Release of Vancomycin From Antibiotic-Bonded Dacron Grafts, Toxicity in Endothelial Cell Culture, and Efficacy Against Graft Infection in an Animal Model

Methicillin-resistant strains of Staphylococcus epidermidis cause an increasing number of prosthetic infections. This prompted us to test the uptake of vancomycin in various graft materials in vitro, its influence on graft healing, and its efficacy against graft infection in pigs. Incubation of six different Dacron graft materials in a vancomycin solution (20 gm/L) was performed. Grafts were then placed in plasma, and samples were taken over 72 hours to determine vancomycin levels. Release of vancomycin ranged from 775 micrograms/cm2 to 3691 micrograms/cm2 after 1 hour of incubation. Gelatin-covered grafts increased release of vancomycin fourfold when incubation time was extended to 24 hours: uncovered grafts or the collagen-covered graft did not. Graft healing was not complicated when a vancomycin-bonded, gelatin-impregnated Dacron graft was implanted to replace the common femoral artery in pigs. Four weeks after implantation, histologic examination revealed normal development of neointima and perigraft scar tissue in the vancomycin-treated (n = 4) and untreated (n = 5) grafts. To test the efficacy of local vancomycin against graft infection, grafts were implanted in the groin of pigs and contaminated with 2 x 10(7) colony-forming units of Staphylococcus aureus. Four weeks after implantation, all grafts were infected in the untreated group (n = 6), with abscess, nonincorporated graft, and detection of S. aureus from the graft. In the treatment group (n = 6) vancomycin was added to the contaminated grafts. As a carrier for the vancomycin, we used a resorbable gelatin-glycerol foam. All grafts healed without infection. The difference between the treated and untreated groups is statistically significant (p < 0.05). We conclude that it may be effective to prevent graft infection with local application of vancomycin if an in situ replacement of infected graft (infected by gram-positive bacteria) is necessary or if there is a high risk of infection by methicillin-resistant- staphylococci.

Hepatitis B virus surface mutations associated with infection after liver transplantation

Background/Aims: Liver transplantation for chronic liver disease due to hepatitis B virus infection is associated with a high risk of graft infection, graft failure and death. Many centres restrict this procedure to those seronegative for HBV-DNA (by hybridisation assay) and use prophylactic polyclonal human hepatitis B specific immunoglobulin to prevent infection of the graft, despite the very high cost. Methods: We describe three patients who underwent liver transplantation for chronic HBV-related disease in whom death was due to fibrosing cholestatic hepatitis following graft infection with hepatitis B virus, despite receiving hepatitis B specific immunoglobulin. Variation within the immunodominant a epitope of HBsAg was sought by analysis of hepatitis B virus sequences and the use of a point mutation assay, following amplification from serum by the polymerase chain reaction. Results: Prior to transplantation, Cases 1 and 2 had mutations at nucleotide 1902 (codon 145), resulting in G-C substitutions, which persisted at a low level after transplantation. In Case 2 a second mutant type with a G-A substitution at nucleotide 1902, became the predominant viral type post transplant. Case 3 had exclusively wild type virus before and after transplantation. The emergence of mutant type virus in Case 2 may have occurred because of immune pressure exerted by high titre anti-HBs detectable for more than 7 months. Cases 1 and 3 received only brief courses of anti-HBs therapy. The mutant viral surface antigen was not detected by a monoclonal antibody-based assay, and therefore the choice of HBsAg assay for post-transplant monitoring of patients who receive liver grafts for hepatitis B virus disesae is important. Conclusions: A search for mutations affecting the a determinant prior to liver transplantation for HBV-related liver disease may help to identify those at risk of failure of prophylaxis. Monoclonal antibodies specific to the codon 145-mutant surface antigen might prevent graft infection, but other mutations might then emerge.

Prophylactic antibiotics prevent bacterial biofilm graft infection

Bacterial biofilm graft infection is due to prostheses colonization by Staphylococcus epidermidis, a pathogen frequently recovered from perigraft tissues of man during vascular procedures despite the use of asepsis and prophylactic antibiotics. The effect of preoperative intraperitoneal cefazolin, administered at a standard (15 or 30 mg/kg) and high (120 mg/kg) dose, on the prevention of bacterial biofilm infection was studied in a rat model. Seventy-four Dacron grafts, colonized in vitro with S. epidermidis to produce an adherent biofilm (3.19 ± 0.71 × 10 7 colony-forming units/cm 2 graft), were implanted in the dorsal subcutaneous tissue at 0.5, 2, and 4 hr after antibiotic administration. The study strain was a slime-producing clinical isolate with minimum inhibitory concentration (MIC) of 15–30 μg/ml to cefazolin. Subcutaneous tissue antibiotic levels were determined at each time interval. One week after implantation, the concentration of bacteria in the surface biofilm by quantitative agar culture was significantly decreased ( P < 0.05) only for grafts implanted when antibiotic tissue levels were greater than or equal to the MIC of the study strain. The result of no growth by biofilm broth culture was significantly achieved ( P < 0.01) only for grafts implanted 0.5 hr after high dose cefazolin, in which the tissue antibiotic level was above the MIC of the study strain. Antibiotics can markedly reduce the bacteria concentration of a prosthetic surface biofilm. The effectiveness of prophylactic antibiotics on the prevention of graft infection is dependent upon maintaining an adequate antibiotic level in the perigraft tissues for the duration of the procedure.

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 μg/gm wet weight, whereas Dacron pretreated with the antibiotic alone contained no measurable drug amounts except for one specimen (0.5 μg/gm) (antibiotic/fibrin vs antibiotic, p < .0005). The corresponding implantation sites to antibiotic/fibrin grafts contained 1.07 ± 0.54 μg/gm antibiotic, whereas in only 2/10 implantation sites of antibiotic grafts low antibiotic levels were found (0.05 and 0.2 μg/gm) (antibiotic/fibrin vs antibiotic, p < 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 < 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. This procedure can serve as a prophylactic tool against perioperative vascular graft infection. (J Vasc Surg 1992; 15:187–93.)

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)

Controlled release of sisomicin from fibrin glue

It seems reasonable to incorporate antibiotics into fibrin glue (FG) used for the presealing of grafts in vascular surgery, to prevent graft infection. This study was conducted to investigate whether FG is appropriate as a biodegradable drug carrier for antibiotics by determining the release behavior of sisomicin (SISO) from FG. By adding 0.12 ml of thrombin (36 U) with 1.75 mg of SISO to a fibrinogen solution (0.12 ml: 9.6 mg), a fibrin glue containing SISO was prepared in a Teflon cast (1 cm in diameter). Then a Dacron ® sheet (1 cm in diameter) was placed on the FG (SISO-FG-Dacron disk; 2.7 mm in thickness). In vitro it was demonstrated that after 8 h and 21 h, 90% and 100% of SISO was released from the SISO-FG-Dacron disk. The SISO-FG-Dacron disk was implanted in an abdominal skin pocket of a rabbit. After 8 h approximately 90% of SISO was released from the FG. The release behavior of SISO in the animal experiment was compatible with temporal courses of serum and tissue SISO levels following implantation of SISO-FG-Dacron disks. One hundred percent SISO from the SISO-Dacron disk(control), prepared by soaking the Dacron sheet in SISO, was released at 1 h. FG is thus concluded to be usable not only as a tissue adhesive but as a drug carrier for controlled release. The in vitro experimental procedure of this study facilitated evaluation of the in vivo release of the drug from FG, as evident from the close agreement of the results of the in vitro experiment with those in the animal experiment.

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 × 108 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 Fischer'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 bactermic challenge. In the 2-day group, four of six control grafts were infected compared with zero of six experimental grafts (p < 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 < 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. After 7 days accelerated healing of the collagen graft surface may, in itself, protect against delayed bacterial seeding.

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

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

Failure of Interferon To Prevent Recurrent Hepatitis B Infection in Hepatic Allograft

Chronic liver disease associated with hepatitis B virus infection is both common and serious; no satisfactory treatment currently exists. Orthotopic liver transplantation is an option for patients with end-stage liver disease associated with hepatitis B virus infection despite the risk of allograft reinfection. Passive immunoprophylaxis has been attempted perioperatively to prevent graft infection but has not been beneficial. Some patients with chronic type B hepatitis have benefited clinically from antiviral therapy and, in particular, interferon, but its use has not previously been reported as an approach to prevent allograft infection. We administered recombinant leukocyte A interferon perioperatively to a patient who underwent liver transplantation for type B chronic active hepatitis and cirrhosis. Circulating hepatitis B virus DNA was found postoperatively while the patient was receiving interferon, and stainable viral antigen subsequently reappeared in the transplanted liver. Thus, the drug failed to prevent viral replication and allograft infection. Thus far, no evidence of progression of the chronic hepatitis has been noted.