THE NATURAL-HISTORY OF BACTERIAL BIOFILM GRAFT INFECTION

A mouse model was developed to study the natural history of vascular p rosthetic graft infection due to Staphylococcus epidermidis. Graft inf ections were established in the back subcutaneous tissue of 46 mice by implantation of Dacron prostheses colonized in vitro with slime-produ cing S. epidermidis to form an adherent bacterial biofilm [1.7 X 10(7) colony forming units (CFU)/cm(2) graft]. Control animals (n = 16) had implantation of sterile Dacron prostheses. None of the control animal s developed a graft infection or graft-cutaneous sinus tract. All stud y animals developed a biofilm graft infection with typical anatomic (p erigraft abscess), microbiologic (low bacterial concentration in surfa ce biofilm), and immunologic (normal white blood count) characteristic s. A graft-cutaneous sinus tract developed in a significantly higher n umber of mice with infected grafts by 8-10 weeks (9 of 21) compared to infected grafts explanted at 2 and 4-6 weeks (1 of 25, P < 0.01) and controls (0 of 16, P < 0.03). By 8-10 weeks, 2 animals had no signs of graft infection and the S. epidermidis study strain was not recoverab le from 7 grafts. The natural history of bacterial biofilm vascular pr ostheses infection in the mouse model was similar to that in man, prov oking a chronic inflammatory process curiously presenting as a perigra ft abscess or graft-cutaneous sinus tract. (C) 1994 Academic Press,Inc .