Figure 5.
Effects of daptomycin on B anthracis AP422 membrane integrity, as measured by flow cytometry. MHBc, DAP, PEN, and CIP represent the control, daptomycin, penicillin G, and ciprofloxacin, respectively. (A) Dot plots of To-Pro-3 iodide vs DiOC2(3) green fluorescence intensity. (B) Correction of To-Pro-3 fluorescence, the ratio of the elevated far-red fluorescence of To-Pro-3 iodide/DiOC2(3) green fluorescence can be used as a size-independent measure of the membrane permeability. Cells treated with daptomycin for as long as 60 min showed no significant To-Pro-3 uptake. CCCP and ciprofloxacin displayed control-like values, which was in sharp contrast to those treated with nisin or penicillin G. cP<0.01.