BIOMATERIAL-ASSOCIATED STAPHYLOCOCCAL PERITONEAL INFECTIONS IN A NEUTROPAENIC MOUSE MODEL

Adhesion of staphylococcal cells to polyethylene with end point-attach ed heparin was quantified by bioluminescence. Staphylococcus epidermid is 3380 and the slime-producing S. epidermidis RP12 adhered to the hig hest extent, and S. lugdunensis 2342 to the least extent. Preincubatio n of the polymer with dialysis fluid reduced adhesion of S. epidermidi s 3380 and RP12 but enhanced that of S. aureus, and preadsorption of t he surface with fibronectin decreased subsequent adhesion of S. epider midis and S. haemolyticus strains. When staphylococci were grown in th e presence of a biomaterial their ability to activate peritoneal cells was decreased. The bactericidal activity was impaired, whereas ingest ion of opsonized coagulase-negative staphylococci (CNS) strains was un affected. With S. epidermidis RP12 the presence of biomaterial did not influence either phagocytosis or bactericidal effect of peritoneal ce lls. After intra-peritoneal challenge with staphylococcal strains, the organ uptake of S. aureus Cowan 1 was increased in normal mice wherea s immunosuppressed mice died. CNS strains increased mainly in the peri toneal cavity of immunosuppressed mice. The uptake of bacteria in live r and kidneys was increased with S. epidermidis 3380, S. lugdunensis 2 343 and S. schleiferi 667-88. Generally, CNS strains persisted in the peritoneal cavity of both normal and immunosuppressed mice. These data indicate that host defense mechanisms, mainly polymorphonuclear neutr ophils, fail to eliminate CNS infections in the peritoneum, and that i nitial adhesion to an implanted biomaterial may be of lesser importanc e in the peritoneal cavity than in e.g. catheter-associated infections . There are strain-specific virulence factors of bacteria, and slime p roducing strains evade the host defense mechanisms more efficiently th an non-slime producing strains.