The present study was undertaken with the aim of defining the differences, if any, in bacteremic infectability of some currently available arterial grafts.
The following prostheses were investigated:
• two kinds of expanded polytetrafluoroethylene (PTFE)
• Dacron knitted double velour
• Dacron knitted pretreated with gelatin
Forty beagle dogs were used . In each animal the infrarenal aorta was resected and replaced by means of ϕ.6 mm segment of:
• PTFE type I 10 dogs
• PTFE type II 10 dogs
• Dacron knitted double velour 10 dogs
• Dacron knitted pretreated with gelatin 10 dogs
At the end of the operation, each animal was administered IV with 100 mL of normal saline containing a suspension of Staphylococcus aureus coagulase-posi tive phage type 5504. The bacterial load was 10
5
in 5 animals of each group, 10
7
in the remaining 5.
The graft was retrieved after forty-five days and studied in the microbiology laboratory (study of graft homogenate) and in the pathology laboratory (study by conventional microscopy of graft healing). When culture yielded a strain of
Staph
.
aureus,
this was retyped for phage 5504 specificity.
All grafts were patent at the end of the experiment: partial thrombosis was, however, observed, coupled with a frank perigraft inflammation in:
• 3 PTFE type 1 (2
Staph.
10
5, 1
Staph
. 10
7)
• 1 PTFE type 2
(Staph .
105)
• 1 Dacron knitted double velour
(Staph .
107
)
Baterial colonies within the graft tissue were evident at microscopy in 4 PTFE grafts and in 1 gelatin-pretreated graft.
Culture was positive and specific in all the gelatin-treated Dacron grafts and in 60% of the nonpretreated Dacron and PTFE grafts.
An optimal result (good healing, no inflammation, no infection) was observed only in 3 PTFE and in 2 "conventional" Dacron grafts.
The possibility is suggested that bacteria may be harbored in graft tissue without any clinically evident effect; moreover, some late graft infection could be attributable to an early bacteremic contamination.
