THE ABILITIES OF A STAPHYLOCOCCUS-EPIDERMIDIS WILD-TYPE STRAIN AND ITS SLIME-NEGATIVE MUTANT TO INDUCE ENDOCARDITIS IN RABBITS ARE COMPARABLE

The abilities of a parent and mutant pair of Staphylococcus epidermidi s strains, the slime-producing parent RP62A and its slime-negative mut ant, to establish endocarditis in a rabbit model of aortic valve endoc arditis and to accumulate and adhere to surfaces in vitro were compare d. Vegetation titer and infection rate depended on the presence or abs ence of a catheter (P = 0.020) and on inoculum size (P < 0.001) but no t on the infecting strain. The ability of the parent strain vis-g-vis its mutant to accumulate in vitro on surfaces as demonstrated in a sli me test did not correlate with any enhancement in the development of e ndocarditis in the rabbit model. In vitro initial adherence rates were identical. Both isolates accumulated to the same reduced extent in vi tro in the presence of serum, albumin, or gelatin. Adhesion was equall y promoted by addition of fibronectin. These data suggest that the in vitro phenomenon of accumulation described as slime production in the absence of serum may not be an important virulence determinant in vivo .