INTERACTIONS OF VANCOMYCIN-RESISTANT ENTEROCOCCI WITH BIOMATERIAL SURFACES

Enterococci are a frequent cause of nosocomial infections and are ofte n found adherent to indwelling catheters. Concern about such device as sociated infections has increased with the appearance of vancomycin re sistant (VR) enterococci. However, the possible influence of vancomyci n resistance in the pathogenesis of biomaterial centered infection has not yet been assessed. Using polyethylene terephthalate (PET) disks a s model surfaces, the authors evaluated possible differences in the ad herence and persistence of vancomycin sensitive (VS) and VR strains of Enterococcus faecium and Enterococcus faecalis on biomaterial surface s in vitro and in vivo. The results indicate that: 1) as expected, the clearance of free VR and VS organisms after intraperitoneal injection into normal mice is equally efficient. 2) In vitro, VR bacteria are r oughly twice as adherent to plasma coated PET surfaces as are VS organ isms. 3) However, in vivo persistence of VS organisms preadherent to b iomaterial implants is 5- to 10-fold better than that of preadherent V R organisms. The authors now believe that a discrete change in bacteri al cell wall composition between VR and VS enterococci may contribute to the substantial differences in bacterial adhesion and survival of a dherent organisms.