Antibiotic prophylaxis of late bacteremic vascular graft infection in a dog model

This study was undertaken to determine the efficacy of a single-dose antibiotic injection to prevent late bacteremic vascular graft infection. Twelve dogs had thoracoabdominal aortic bypass with expanded polytetrafluoroethylene grafts. One month later, a bacteremic challenge was produced by rapid intravenous injection of 5 x 10(8) Staphylococcus aureus. Dogs were treated by pairs, each dog of a pair being randomly assigned to receive either 0.5 g ceftriaxone (group I, n = 6) or saline (group II, n = 6), intramuscularly, 90 minutes before challenge. Grafts were harvested seven days after bacteremic challenge. They were cut into 10 fragments, each of which were submitted to bacterial counts. Results of bacterial counts were expressed as colony forming units per square centimeter of graft segment. The overall infection rates were zero of six grafts in group I and four of six in group II (p less than 0.05). In group I, none of the 60 graft fragments were found to be culture positive (p greater than 0.01). Bacterial counts from the 24 infected fragments were highly variable, ranging from 12 colony forming units/cm2 to 64 x 10(3) colony forming units/cm2. Serial quantitative blood cultures revealed a similar decrease of bacteremia in both groups with 2.4 +/- 0.9 x 10(2) (group I) and 1.2 +/- 0.9 x 10(2) (group II) colony forming units/ml at three hours. Mean ceftriaxone serum level was 26 +/- 18 mg/L at the time of bacteremic challenge. These data suggest that a single dose of ceftriaxone given before bacteremic challenge is sufficient to prevent late bacteremic vascular graft infection in this model.(ABSTRACT TRUNCATED AT 250 WORDS)