The glycopeptides vancomycin and teicoplanin constitute an important class of antibiotics for the treatment of severe infections due to Gram-positive bacteria, including staphylococci, enterococci, and streptococci. These antibiotics inhibit late stages in bacterial cell wall peptidoglycan synthesis? Their mode of action is unique and differs from that of the ~-lactams. Glycopeptides bind to peptidoglycan precursors that contain Dalanyl-D-alanine at their free carboxyl end and prevent, by steric hindrance, polymerization and cross-link of peptidoglycan (Figure 1). Enterococci constitute a normal component of the human intestinal flora but can provoke opportunistic infections in compromised patients. 2 These organisms have been implicated mostly in urinary tract infections, abdominal abscesses, and endocarditis episodes. Enterococcal infections cause significant therapeutic difficulties because of the high incidence of isolates multiply resistant to antimicrobial agents. 3 Recently, there have been a number of reports of the isolation of vancomycin-resistant enterococci from various parts of the world, including Europe and the USA. 4-7 The species involved include Enterococcus faecium, E. faecalis, E. avium, E. gallinarum, and E. casseliflavus. The resistant strains can be divided into three phenotypic classes, VANA, VANB, and VANC (Table 1), on the basis of the level of resistance to glycopeptides, cross-resistance between vancomycin and teicoplanin, and inducibility or constitutivity of resistance (Table 1). 8 VANA strains, mainly E. faecium, are inducibly resistant to high levels of vancomycin and teicoplanin. Resistance is inducible by glycopeptides only, either vancomycin or teicoplanin, and induced cells are cross-resistant to all glycopeptides. 9 There is no cross-resistance between glycopeptides and lipopeptide (daptomycin) or glycolipodepsipeptide (ramoplanin) antibiotics 4 resulting from differences in the mechanisms of action of the three groups of drugs. 1 VANB strains have inducible moderate levels of resistance to vancomycin and remain susceptible to teicoplanin? ° These strains of E. faecium and E. faecalis are less represented among clinical isolates in Europe but their incidence may be underestimated because this phenotype is difficult to detect by the disk-agar diffusion test and by automated techniques for antibiotic susceptibility determination. s E. gallinarum constitutes the VANC class; this bacterial species exhibits constitutive resistance to vancomycin