• The production of an exopolysaccharide (mucin) by some Staphylococcus epidermidis strains facilitates bacterial adhesion to prosthetic vascular grafts and may play an important role in adherence-mediated growth. An in vitro model was developed to measure the differential adherence of mucin-producing (RP-12) and nonmucin-producing (SP-2) S epidermidis strains onto expanded polytef and velour knitted Dacron graft material. After incubation in a 107/mL suspension of organisms, graft specimens were repeatedly washed to remove nonadherent organisms and then sonicated to dislodge adherent organisms. Bacterial adherence was calculated from a quantitative culture of the sonication effluent. Both S epidermidis strains adhered in ten to 100 times greater numbers to the knitted Dacron graft material than to expanded polytef. The production of an exopolysaccharide by the RP-12 strain significantly increased adherence to both graft types compared with the SP-2 strain. The increased adherence of the RP-12 strain was inhibited by adding D-mannosamine to the inoculum. The in vitro model developed is well suited for further study of the mechanisms by which bacteria adhere to and colonize vascular grafts.
(Arch Surg 1986;121:89-95)