Vancomycin and teicoplanin Etest results for VREF isolates. The two clinical VREF strains of E. faecium, ZP2298 and ZP2171, had a high level of resistance to vancomycin and teicoplanin (MICs > 256 μg/ml). After conjugation, the transconjugants of these two strains of E. faecium, FB2298 and FB2171, exhibit high-level resistance to vancomycin (MICs > 256 μg/ml), with resistant subcolonies present in the clear zone of inhibition around the teicoplanin Etest strip, described for teicoplanin-heteroresistant isolates. The resistant subcolonies, E. faecium FBV2298 and FBV2171, had teicoplanin MICs of 96 and >256 μg/ml, respectively. E. faecium FBG2298 and FBG2171 strains were generated after three serial passages of E. faecium FBV2298 and FBV2171, respectively.