rifampin and silver-acetate

The primary objective of this study was to compare the efficacy of a collagen silver-coated polyester graft, InterGard, with a gelatin-sealed graft, Gelsoft, both soaked in rifampin, for resistance to direct bacterial contamination in an animal model. The second objective was to confirm the lack of inflammation from silver acetate. Vascular grafts, 6 mm in diameter, were implanted in the infrarenal aorta of 28 dogs. Intravenous cefamandole (20 mg/kg) was injected intraoperatively in all dogs. The dogs were divided into three groups. Group I included 12 dogs. Six dogs received silver grafts and six dogs received gelatin-sealed grafts, all soaked with rifampin. Grafts implanted in group I were directly infected with methicillin-resistant Staphylococcus aureus (MRSA). Group II included also six silver grafts and six gelatin-sealed grafts, all soaked with rifampin. Dogs of group II were directly infected with Escherichia coli. Group III comprised four dogs, which received gelatin unsealed grafts, directly infected with MRSA, the control group. All dogs were followed by regular clinical examination, including blood cultures. Grafts in groups I and III and in group II were harvested at 30 days and 10 days, respectively. Bacterial analyses were performed on the explanted grafts. Histology was performed on both the tissue samples and the anastomotic sites of the harvested grafts. In group I, no grafts were infected with MRSA, irrespective of graft type. In group II, no silver grafts were infected with E. coli, whereas one (16.6%) of six gelatin-sealed grafts was infected (p = 0.317). In group III, three (75%) of the four grafts were infected with MRSA. The infection rate in the silver grafts and the gelatin-sealed grafts soaked in rifampin in group I compared with the unsealed gelatin grafts in group III was statistically significantly different (p < 0.05). There was no statistically significant difference in the inflammation score, obtained by histological analysis, between rifampin-soaked silver and Gelsoft grafts in either group I or group II. There were signs of necrosis at the anastomoses in three (25%) gelsoft grafts of 12 in groups I and II. There were no clinical or biological signs of inflammation from use of silver-coated grafts. These results indicate that collagen silver-coated grafts and gelatin-sealed grafts, both soaked in rifampin, provide resistance against MRSA and E. coli. There was a trend toward better resistance but without statistical signi

Topics: Acetates; Animals; Anti-Bacterial Agents; Aorta; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Coated Materials, Biocompatible; Collagen; Disease Models, Animal; Dogs; Escherichia coli; Escherichia coli Infections; Gelatin; Inflammation; Methicillin-Resistant Staphylococcus aureus; Polyesters; Prosthesis Design; Prosthesis-Related Infections; Rifampin; Silver Compounds; Staphylococcal Infections; Time Factors

In situ replacement of infected vascular grafts is an accepted alternative to total graft excision and extraanatomic replacement. Its success relies upon the ability of the newly inserted graft to resist recurrent infection. This study compares the efficacy of two methods used to reduce the risk of graft reinfection: rifampicin soaking versus silver bonding of grafts. The grafts' resistance to infection was tested in vitro in two protocols, each using a panel of seven common bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). The length of time the grafts remained free of organisms was compared between the groups. Both the silver graft and the rifampicin-soaked graft were significantly better than control graft at preventing bacterial growth on the graft surface. The rifampicin inhibited the growth of the gram-positive organisms, including MRSA, significantly better than the silver graft on days 2 and 3 (p < 0.001). Conversely, the silver graft was significantly more effective against the gram-negative organisms until day 4 (p < 0.0001). Both types of graft inhibit the in vitro growth of bacteria more effectively than controls, with rifampicin being most effective against gram-positive organisms and silver being best against the gram-negative organisms.

Topics: Acetates; Animals; Antibiotics, Antitubercular; Blood Vessel Prosthesis Implantation; Coated Materials, Biocompatible; Disease Models, Animal; Escherichia coli Infections; Horses; Methicillin Resistance; Models, Cardiovascular; Prosthesis Design; Prosthesis-Related Infections; Rifampin; Silver Compounds; Staphylococcal Infections; Time Factors

The purpose of this study was to compare the efficacy of rifampin-bonded gelatin-sealed and silver acetate/collagen-coated knitted polyester prostheses for the prevention of bacteremic graft infection in an animal model.. Eighteen 6.0-mm polyester grafts (length, 5.0 cm) were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into four groups as a function of type of prosthesis implanted. The dogs in groups I (n = 3) and II (n = 3) received control gelatin-sealed or collagen-coated polyester prostheses, respectively. In group III (n = 6), the dogs received rifampin-bonded gelatin-sealed polyester prostheses. In group IV (n = 6), the dogs received silver/collagen-coated polyester prostheses. Two days after implantation, the grafts were challenged with 6 x 10(9) Staphylococcus aureus intravenously. One week after implantation, the grafts were harvested with sterile technique. Quantitative cultures were obtained from all the harvested grafts. The results were expressed as colony-forming units per cm(2) of graft material. Bacteriologic study was also performed on various tissue samples. The chi(2) test was used to compare the culture proven infection of control and antimicrobial grafts.. All the control grafts were infected with S aureus at the time of removal. Five of the six silver/collagen-coated grafts were infected, whereas none of the six rifampin-bonded gelatin-sealed grafts grew S aureus (P <.01). There was no significant difference in the number of positive culture results of organ samples between the different groups of dogs.. These results indicate that rifampin-bonded gelatin-sealed polyester grafts are significantly more resistant to bacteremic infection than are silver/collagen-coated polyester grafts in a highly challenging model.

Topics: Acetates; Animals; Biocompatible Materials; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Dogs; Polyesters; Prosthesis-Related Infections; Rifampin; Silver Compounds; Staphylococcal Infections