Emergence of high-level resistance to glycopeptides in Enterococcus gallinarum and Enterococcus casseliflavus.

Enterococcus gallinarum BM4231 and Enterococcus casseliflavus BM4232, isolated from the feces of a patient under oral therapy with vancomycin, were resistant to high levels of vancomycin (MICs of > 256 micrograms/ml) and teicoplanin (MICs of 128 and 64 micrograms/ml, respectively). This phenotype is new for these bacterial species that are naturally resistant to low levels of vancomycin and appears to be due to in vivo acquisition of plasmid pIP218 carrying the vanA gene cluster.