THE VANB GENE CONFERS VARIOUS LEVELS OF SELF-TRANSFERABLE RESISTANCE TO VANCOMYCIN IN ENTEROCOCCI

Thirty-nine strains of Enterococcus faecium and Enterococcus faecalis resistant to vancomycin and susceptible to teicoplanin on disk suscept ibility testing (phenotypic class B) were isolated in 15 hospitals in Europe and the United States. The MICs of vancomycin for these strains ranged from 4 to 1024 mug/mL. Part of the vancomycin resistance gene vanB from E. faecalis V583 hybridized with a single but variably sized HindIII-KpnI fragment of total DNA from all 39 strains. This indicate s that a single class of resistance determinants accounts for the VanB phenotype. No hybridization was detected with DNA from intrinsically resistant Enterococcus gallinarum or Enterococcus casseliflavus. Hybri dization with DNA from enterococcal strains susceptible to or with acq uired resistance to vancomycin and teicoplanin was not observed. The g enes conferring resistance to vancomycin were self-transferable to oth er Enterococcus strains in 14 of the 39 strains. It thus appears that vanB confers various levels of conjugative vancomycin resistance in en terococci.