Fig. 1.

H. ducreyi has a PMF-dependent mechanism for LL-37 and HBD-3 resistance. Shown are bactericidal assays with 35000HP after pretreatment with the PMF inhibitor CCCP, or its diluent DMSO, and either LL-37 (2 μg/ml) (A) or HBD-3 (10 μg/ml) (B). The data represent the means and standard errors of four independent assays. The single asterisks indicate significant differences from the control, which received neither CCCP nor AP (P < 0.02); the double asterisks indicate significant differences in AP sensitivity with or without CCCP pretreatment (P ≤ 0.001).