Flow cytometry as a tool to determine the effects of cell wall-active antibiotics on vancomycin-susceptible and -resistant Enterococcus faecalis strains.

Flow cytometry and confocal microscopy were used to study the effects of vancomycin, daptomycin, telavancin, and PA1409, a new investigational vancomyquine, on the morphology, membrane potential, and permeability of glycopeptide-susceptible and -resistant Enterococcus faecalis strains. Daptomycin exerted the most pronounced effects on bacterial size and bacterial permeability against susceptible and resistant strains.