Rifampicin impregnation of a protein-sealed Dacron graft: an infection-resistant prosthetic vascular graft.

A gelatin-sealed knitted Dacron vascular graft was prepared by passive impregnation with rifampicin and implanted in the common carotid artery of 10 merino sheep. Another 10 merino sheep had an untreated graft inserted. The graft was topically inoculated with 1 mL of 10(8) colony forming units per mL of Staphylococcus aureus before wound closure. The grafts were harvested at 3 weeks and cultured. All untreated grafts and surrounding tissues became infected. One of the 10 grafts treated with rifampicin became infected (P = 0.0002) and 4 sheep with rifampicin-treated grafts had surrounding tissue infection. No bacteria cultured from the rifampicin-treated sheep developed resistance to rifampicin.     

Prophylaxis against Staphylococcus epidermidies vascular graft infection with rifampicin-soaked,gelatin-sealed Dacron

An animal model was used to assess the efficacy of rifampicin-impregnated, gelatin-sealed Dacron in the prevention of vascular graft infections caused by Staphylococcus epidermidis. Under a general anaesthetic an interposition graft was placed into sheep carotid artery. On completion of the operation 1 ml of normal saline containing 10⁸ colony forming units (cfu) of a slime-producing S. epidermidis was inoculated directly onto the graft. After 3 weeks the graft was harvested. Swabs were taken of perigraft tissues, and of external and internal aspects of the graft. A 3–5-mm segment of the graft was incubated in broth medium and a second segment was ground for 5 min and incubated in broth medium. The presence of abscess formation and anastomotic disruption was assessed. Ten sheep received a gelatin-sealed Dacron graft (control), while nine received the same graft impregnated with rifampicin at a concentration of 1.2 mg/ml (treated). Eight of 10 control grafts were infected, with 30 of 50 possible cultures positive, compared with four of nine treatment grafts infected (P = 0.13) and 13 of 45 cultures positive (P = 0.004). The control group had four abscesses and two anastomotic disruptions; the treatment group had no abscesses (P = 0.05) or anastomotic disruptions (P = 0.26). Other organisms were isolated from nine of the 12 infected grafts, most commonly Staphylococcus aureus. There was no development of resistance to rifampicin. Rifampicin-impregnated, gelatin-sealed Dacron is successful at reducing the incidence of S. epidermidis vascular graft infection.     

Rifampin protection against experimental graft sepsis

The risk of infection in vascular prosthetic conduits appears to be greatest in the perioperative period and the organism most frequently found is Staphylococcus aureus. Previous work suggests that antibiotics must be chemically bonded to the material to resist rapid washout caused by the flow of blood through the graft. The exception to this is rifampin, which remains fixed in Dacron prostheses after passive addition of the agent to aliquots of blood used to clot the interstices of porous Dacron grafts. This characteristic of rifampin is presumed to be caused by its poor water solubility. This potential infection resistance was challenged in a standard model of a canine infrarenal aortic graft by intravenous infusion of S. aureus organisms (10(7)) in the perioperative period. The grafts of five animals were preclotted with 9 ml of autogenous blood plus 1 ml of rifampin (60 mg/ml). A second group had similar procedures with 1 ml of cefazolin (238 mg/ml) substituted for the rifampin, and a control group had 1 ml of saline solution added to the 9 ml aliquot of blood. The animals were killed at 3 weeks and examined for clinically apparent infection. Rings of the graft material were also removed aseptically and cultured. All five grafts preclotted with cefazolin had clinical and culture evidence of infection (S. aureus), as did the grafts of three of the five control dogs. None of the grafts preclotted with rifampin was infected (p less than 0.05). Addition of rifampin to the blood used to clot the graft interstices appears to be a simple way of imparting graft resistance to perioperative sepsis.     

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.     

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.     

Establishment of a vascular graft infection model in the sheep carotid artery

A study was performed to assess whether a model of vascular graft infection could be established in sheep carotid artery. Either a protein sealed Dacron or a polytetrafluoroethylene (PTFE) graft was used in 22 sheep while a control operation was performed on 4 animals. Staphylococcus aureus in concentrations of 10(2), 10(4), 10(6) or 10(8) colony-forming units (CFU) was inoculated into the wound before closure. No infection occurred with an inoculum of 10(2). The lowest concentration of organism producing infection was 10(4) for PTFE, 10(6) for Dacron and 10(8) for controls. Six of eleven Dacron grafts and seven of ten PTFE grafts became infected. The sheep carotid artery has proven a satisfactory model for studies of vascular graft infection.     

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)     

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.     

Rifampin and Triclosan but not silver is effective in preventing bacterial infection of vascular dacron graft material.

OBJECTIVES: To evaluate the efficacy of silver- or Triclosan-coated prosthetic material compared to Rifampin bonded Dacron concerning their resistance to infection following subcutaneous implantation and contamination with Staphylococcus aureus. DESIGN: Animal experimental study in mice. MATERIAL AND METHODS: Thirty-six C3H/HcN mice (Charles River Lab., Sulzfeld, Germany) with a weight between 24 and 27 g were randomised into six groups counting six animals each. Group I: control, gel-sealed dacron graft, group II: gel-sealed dacron graft and local contamination, group III: Intergard-Silver-prosthesis and contamination, group IV: silver/gel-sealed dacron prosthesis (test graft) and contamination, group V: Rifampin-bonded gel-sealed graft and contamination, group VI: Triclosan/collagen-coated dacron graft and contamination. Dacron graft material 0.8x1 cm was subcutaneously implanted in mice. Local contamination with 2x10(7)/0.2 ml S. aureus ATCC 25923 was carried out in groups II to VI. On day 14 the animals were killed and the grafts were explanted. The microscopic, histologic and microbiological evaluation of the graft material and the perigraft tissue was performed. RESULTS: In control group I no case of infection was detected. In group II, 6 of 6 animals showed infection. In group III (Intergard-Silver) and group IV (silver/gel-test graft) were 6 of 6, in group V (Rifampin) only 1 of 6 grafts and in group VI (Triclosan) 4 of 6 grafts were infected. The difference between the low rate of infection in group V (Rifampin) in comparison to the completely infected groups III and IV (Silver) as well as the control group II was significant. Treatment of grafts with Triclosan could prevent infection only in 1/3 of the cases in group IV. CONCLUSION: Silver coating failed to prevent graft infection material. A potential antimicrobial property was evident for Triclosan whereas Rifampin-bonded grafts exhibit a significantly reduced infection rate. Thus, silver-coated vascular grafts cannot ensure protection from vascular graft infection.     

Linezolid alone and in combination with rifampicin prevents experimental vascular graft infection due to methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis

BACKGROUND: In this report we describe the in vivo antibacterial activity of linezolid in an experimental graft infection model in rats and compare it with teicoplanin. The objective of this study was also to determine the effects of the interaction of linezolid when it was combined with rifampicin and test this effect against strains of methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. MATERIALS AND METHODS: Graft infections were established in the subcutaneous tissue of 130 Wistar rats by implantation of Dacron grafts followed by a topical inoculation with 2 x 10(7) CFU of clinical isolates of MRSA and MRSE. The study included a control group and six groups for each of the staphylococcal strains: an inoculated group that did not receive any antibiotic prophylaxis, two inoculated groups that received intraperitoneal prophylaxis with teicoplanin or linezolid alone, an inoculated group that received rifampicin-soaked grafts, and two inoculated groups that received a combination prophylaxis consisting of intraperitoneal teicoplanin or linezolid and rifampicin-soaked grafts. RESULTS: There was a reduction in the quantitative bacterial graft cultures in all prophylaxis groups when compared with inoculated control groups. There was not a statistically significant difference between linezolid and teicoplanin prophylaxis groups. The best results were obtained by a combination of rifampicin-soaked grafts with linezolid or teicoplanin. CONCLUSIONS: We found no evidence to suggest that linezolid differs from teicoplanin regarding effectiveness in the prevention of prosthetic vascular graft infection. Linezolid plus rifampicin and teicoplanin plus rifampicin are demonstrated to be valuable prophylactic regimens.     

RIFAMPICIN IMPREGNATION OF A PROTEIN-SEALED DACRON GRAFT: AN INFECTION-RESISTANT PROSTHETIC VASCULAR GRAFT

A gelatin-sealed knitted Dacron vascular graft was prepared by passive impregnation with rifampicin and implanted in the common carotid artery of 10 merino sheep. Another 10 merino sheep had an untreated graft inserted. The graft was topically inoculated with 1 mL of 10⁸ colony forming units per mL of Staphylococcus aureux before wound closure. The grafts were harvested at 3 weeks and cultured. All untreated grafts and surrounding tissues became infected. One of the 10 grafts treated with rifampicin became infected (P= 0.0002) and 4 sheep with rifampicin-treated grafts had surrounding tissue infection. No bacteria cultured from the rifampicin-treated sheep developed resistance to rifampicin.     

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)     

Gelatin-sealed dacron graft is not more susceptible to MRSA infection than PTFE graft.

OBJECTIVES: The purpose of this experimental study was to compare the susceptibility of gelatin-sealed Dacron and PTFE prostheses to infection by MRSA. DESIGN: Prospective, randomized, controlled animal study. MATERIALS AND METHODS: Graft infections were established in the subcutaneous tissues of 60 female Spraque-Dawley rats by the implantation of gelatin-sealed Dacron or PTFE prostheses followed by topical inoculation with methicillin-resistant Staphylococcus aureus. The study groups were as follows: (1A) uncontaminated gelatin-sealed Dacron group, (1B) untreated contaminated gelatin-sealed Dacron group, (1C) contaminated gelatin-sealed Dacron group with intraperitoneal teicoplanin treatment, (2A) uncontaminated PTFE group, (2B) untreated contaminated PTFE group, and (2C) contaminated PTFE group with intraperitoneal teicoplanin treatment. The grafts were removed after 7 days and evaluated for infection by counting the number of adherent bacteria on the graft material after rinsing and sonication. The perigraft tissue was harvested for histopathological study. To investigate the existence of any infection, blood samples were collected by cardiopuncture for a culture analysis. RESULTS: No significant difference in bacteria counts was observed between gelatin-sealed Dacron and PTFE grafts. In groups 1A and 2A, there was no infection detected. The bacterial counts for MRSA were 7.4 x 10(5) in group 1B and 8.6 x 10(5) in group 2B. There was also no infection in groups 1C and 2C. While the difference between group 1B and 2B was not significant (p>.05), bacterial counts in group 1B or 2B were significantly higher than those in other groups. Blood cultures were only positive in four rats in group 1B and in two rats in group 2B. The severities of the inflammation of the perigraft tissues was low in groups 1A and 2A, high in groups 1C and 2C, and between the range from low to moderate in groups 1B and 2B. CONCLUSION: The susceptibility of gelatin-sealed Dacron to bacterial infection was not higher than that of PTFE.     

Prevention of vascular graft infection by rifampin bonding to a gelatin-sealed dacron graft

This study examines the efficacy of rifampin bonding to a gelatin-sealed knitted Dacron graft to prevent perioperative bacteremic vascular graft infection. Antibiotic bonding was obtained by soaking grafts for 15 minutes in a 1 mg/ml saline solution of rifampin at 37°C. Nineteen dogs had thoracoabdominal aortic bypass: seven (group I) received a rifampin treated graft; six (group II) received an untreated gelatin-coated graft; and six (group III) received an uncoated Dacron graft. Two days later bacteremic challenge was produced by rapid intravenous injection of 5×10 ⁵ colony forming units of methicillin resistantStaphylococcus aureus.Grafts were harvested five days after this challenge and cut into 10 fragments, each submitted to bacterial counts. Results were expressed as CFU/cm ² of graft material. In group I, no graft was infected, whereas all grafts in groups II and III were infected (p<0.05). Median bacterial counts from the infected fragments (median±SD) were similar in groups II (2.5×10⁵ CFU/cm²) and III (4×10⁴ CFU/cm²). Blood cultures at time of sacrifice were negative in all dogs in group I and positive in five of six dogs in groups II and III. Cultures of liver, spleen, kidney, and lung specimens were always negative in group I and positive in 22 of 24 specimens in group II and 23 of 24 specimens in group III. Soaking a gelatin-sealed Dacron graft in rifampin solution evidently prevents early bacteremic graft infection and secondary foci of infection in this model.Presented at the Annual Meeting of the French Vascular Surgery Society, Nancy, France, May 18–19, 1990.     

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 10(9)cfu/ml. Group 2 (n=6) received systemic prophylaxis (1 g cephamandole) and were inoculated with 10(5) cfu/ml (n=3) or 10(7) 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 10(9)cfu/ml. In group 5 and 6 grafts were soaked in a rifampicin solution before use and inoculated with 10(9) 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 10(9) cfu/ml ensured graft infection. Systemic 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.     

Temporin A as a prophylactic agent against methicillin sodium-susceptible and methicillin sodium-resistant Staphylococcus epidermidis vascular graft infection

OBJECTIVE: The purpose of this study was to investigate the efficacy of temporin A as a prophylactic agent in a rat model of vascular graft infection from methicillin sodium-susceptible and methicillin sodium-resistant Staphylococcus epidermidis. METHODS: The prospective, randomized, controlled animal study set in a research laboratory in a university hospital used 280 adult male Wistar rats (weight range, 280 to 350 g). Graft infections were established in the back subcutaneous tissue of rats with implantation of 1-cm(2) sterile Dacron grafts followed by topical inoculation with 2 x 10(7) colony-forming units of S epidermidis. The study for each staphylococcal strain included: one control group (no graft contamination), one contaminated group that did not receive any antibiotic prophylaxis, one contaminated group that received temporin A-soaked graft, two contaminated groups that received perioperative intraperitoneal cefazolin (30 mg/kg) or vancomycin hydrochloride prophylaxis (10 mg/kg), and two contaminated groups that received temporin A-soaked graft and perioperative intraperitoneal cefazolin (30 mg/kg) or vancomycin hydrochloride (10 mg/kg) prophylaxis. All grafts were explanted at 7 days after implantation. The main outcome measure was quantification of bacterial contamination. RESULTS: Overall, the perioperative prophylaxis based on soaked grafts was not significantly different to that of parenteral vancomycin hydrochloride. Only the combination between temporin A and vancomycin hydrochloride produced a complete bacterial inhibition for both strains. CONCLUSION: Temporin A showed a similar antibacterial in vitro activity against the two different strains. The in vivo results suggest its potential use in providing prophylaxis to direct graft contamination when used in combination with parenteral vancomycin hydrochloride.     

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)     

Prophylaxis against Staphylococcus aureus vascular graft infection with mupirocin-soaked, collagen-sealed dacron

A rat model was used to investigate the efficacy of mupirocin in the prevention of vascular prosthetic graft infections. The effect of mupirocin-soaked Dacron was compared with the effect of rifampin-soaked, collagen-sealed Dacron in the rat model of graft infection caused by methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus. Graft infections were established in the back subcutaneous tissue of 195 adult male Wistar rats by implantation of 1-cm(2) Dacron prostheses followed by topical inoculation with 5 x 10(7) colony-forming units of S. aureus. The study included a control group (no graft contamination), two contaminated groups that did not receive any antibiotic prophylaxis, two contaminated groups in which perioperative intraperitoneal amoxicillin clavulanate prophylaxis (50 mg/kg) was administered, four contaminated groups that received mupirocin- or rifampin-soaked graft, and four contaminated groups that received mupirocin- or rifampin-soaked graft and perioperative intraperitoneal amoxicillin clavulanate prophylaxis (50 mg/kg). The grafts were sterilely removed 7 days after implantation and the infection was evaluated by using sonication and quantitative agar culture. Data analysis showed that the efficacy of mupirocin against both strains was significantly different from that of the untreated control. In addition, mupirocin was more effective than rifampin against the methicillin-resistant strain. Finally, only the combination of mupirocin and amoxicillin clavulanate produced complete suppression of growth of all strains.     

Prevention of Staphylococcus aureus graft infection by a new gelatin-sealed vascular graft prebonded with antibiotics

OBJECTIVE: The aim of this study was to evaluate the efficacy of a new gelatin-sealed graft prebonded with two antibiotics in resisting infection with Staphylococcus aureus (S aureus) A980142 after direct bacterial application in a dog model. METHODS: Twelve 6.0-mm polyester grafts were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into two groups. A test group (n = 6) received experimental antibiotic-bonded gelatin-sealed knitted polyester grafts, loaded with two antibiotics, rifampin and tobramycin. A control group (n = 6) received commercial gelatin-sealed knitted polyester grafts. At the end of graft implantation, 50 mul of a 1.8 x 10(4) CFU/mL S aureus solution were instilled directly over the graft. One week after implantation, 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 surface of the graft. Bacteriological study was also performed on various tissue samples. The chi(2) test was used to compare the culture proven infection of control and antibiotics-bonded grafts. RESULTS: Mean inoculum size was similar in the two groups of dogs. Five of the six control grafts grew S aureus A980142 at the time of graft removal, whereas none of the six antibiotic-bonded gelatin-sealed grafts were infected (P = .0192). None of the organ samples were infected in the group implanted with antibiotic-bonded grafts, whereas 15/34 samples grew S. aureus in the control group. CONCLUSION: These results indicate that this gelatin sealed graft prebonded with two antibiotics resists infection caused by S aureus graft contamination in a dog model.     

Experimental colonization of a polyester vascular graft with Staphylococcus aureus: a quantitative and morphologic study

Colonization of a polyester (Dacron) vascular graft by Staphylococcus aureus 209P-R was studied. Twenty-five dogs had thoracoabdominal aortic bypass. After intervals of 2 hours (three dogs), 8 days (five dogs), 1 month (six dogs), 2 months (six dogs), or 6 months (five dogs), a bacteremic challenge was produced by intravenous injection of 6 x 10(8) colony-forming units of S. aureus. Two hours later grafts were removed and cut into 10 fragments, each submitted to bacterial counts and scanning electron microscopic studies. Results of bacterial counts were expressed in colony-forming units (CFU) per square centimeter of graft segment (median [lower to upper quartiles]). Normal canine aortas (n = 2) used as controls trapped no bacteria. Colonization of Dacron grafts varied according to the duration of graft function (p less than 0.01): after 2 hours, 4416.5 CFU (1158 to 9073 CFU); after 8 days, 1515 CFU (963 to 2893 CFU); after 1 month, 199 CFU (86 to 538 CFU); after 2 months, 615 CFU (243 to 1407 CFU); and after 6 months, 1 CFU (1 to 5 CFU). Heavily colonized fragments were observed for duration of graft function of 2 months or less, whereas at 6 months all the fragments trapped fewer than 50 CFU/cm2 of graft segment. Scanning electron microscopy showed that colonization was closely associated with healing. Staphylococcal entrapment was related to the amount of fibrin deposits, which were especially abundant where the thrombotic matrix was unorganized and on bare polyester filaments. Graft colonization is especially to be feared in the first weeks after graft implantation, an observation which may help to define guidelines for preventing hematogenous vascular graft infection.