Table 3. Effect of efflux pump inhibitors on vancomycin susceptibility in E. faecium KU22001

Compound	MIC (mg/L)1)
Vancomycin	>512
Van+CCCP	>512
Van+CPZ	>512
Van+reserpine	0.5 (decrease, factor of 1,024)
Van+orthovanadate	>512

Van, vancomycin; CCCP, carbonyl cyanide m-chlorophenylhydrazone; CPZ, chlorpromazine.
The MICs were assayed in a range of 2-fold dilutions of vancomycin in the presence of non-lethal concentrations of the following compounds: CCCP, 8 mg/L; CPZ, 16 mg/L; Reserpine, 32 mg/L; Orthovanadate, 256 mg/L. Values in brackets correspond to the decrease in MIC with respect to the MIC of vancomycin alone.