Inhibition of vancomycin-resistant enterococci by an in vitro continuous-flow competitive exclusion culture containing human stool flora

An in vitro anaerobic continuous-flow competitive exclusion (CFCE) culture model was used to study the ability of human stool flora to inhibit the gro wth of vancomycin-resistant (VR) enterococci (VRE). The CFCE culture was es tablished from a stool sample obtained from a healthy adult. When 10(3) or 10(6) cfu/mL of VR Enterococcus faecium were added to the CFCE culture, the VRE were eliminated within 6 or 9 days, respectively. When 10(7) cfu/mL of the CFCE culture was added to a continuous-flow culture that contained 10( 7) cfu/mL of VRE, the density of VRE was reduced but not eliminated. These data support the hypothesis that the indigenous intestinal flora inhibit gr owth of VRE and suggest that CFCE cultures may be a useful means to study i nteractions between the indigenous flora and VRE.