Distribution of vancomycin MICs. (a) Vancomycin MICs of the 67 vanB type VRE (light grey) and of the subset of 56 vanB outbreak strains (dark grey) determined by microdilution in cation-adjusted Mueller-Hinton broth. (b) Etest® Vancomycin results of the 56 vanB type outbreak VRE tested on MH agar using McFarland standard 0.5 and (c) and on Brain Heart Infusion agar using McFarland standard 2.0. The vancomycin MIC from microdilution in cation-adjusted Mueller-Hinton broth was included in Figures 1b and 1c for reasons of comparison. The dotted line in Figure 1a depicts the EUCAST breakpoint for clinical resistance of >4 mg/L and the dashed line depicts the CLSI resistance breakpoint of ≥32 mg/L (CLSI intermediate range of 8–16 mg/L, susceptible breakpoint for EUCAST and CLSI is ≤4 mg/L). The numbers on top of the bars display the number of isolates. Please notify that Etest® Vancomycin allows assessing a broader spectrum of antibiotic dilution concentrations than doubling dilutions assessed in MH broth microdilution.