FIG 6.
Comparison of ramoplanin antibacterial activity against MSSA ATCC 25923 with mode-of-action parameters. *, data are from the published literature (other data are from this study). Inhibition of the MurG-catalyzed reaction of peptidoglycan biosynthesis has been reported to occur at a concentration significantly higher than the MIC (IC50, 20× MIC against MSSA ATCC 25923), while ramoplanin inhibits transglycosylation at the concentration correlated with the MIC (IC5, 0.25× MIC against MSSA ATCC 25923) (22). Ramoplanin binds to cell membranes and induces membrane depolarization at concentrations close to or above the MBC, which corresponded to its bactericidal concentrations against MSSA observed in time-kill studies.