Engineered cationic antimicrobial peptides to overcome multidrug resistance by ESKAPE pathogens

Abstract

Multidrug resistance constitutes a threat to the medical achievements of the last 50 years. In this study, we demonstrated the abilities of two de novo engineered cationic antibiotic peptides (eCAPs), WLBU2 and WR12, to overcome resistance from 142 clinical isolates representing the most common multidrug-resistant (MDR) pathogens and to display a lower propensity to select for resistant bacteria in vitro compared to that with colistin and LL37. The results warrant an exploration of eCAPs for use in clinical settings.

FIG 1

Helical wheel analysis of the amphipathic structures of LL37, WLBU2, and WR12 using HeliQuest (http://heliquest.ipmc.cnrs.fr/). The primary sequence of LL37 displays 14 different amino acids distributed as an imperfect cationic amphipathic structure. In contrast, nature-inspired but sequence-optimized eCAPs are composed of only three (WLBU2) or two (WR12) different amino acids modeled to form idealized amphipathic helices. The arrows indicate the directions and magnitudes of the hydrophobic moments (μH) determined for each peptide; N, amino terminus; C, carboxy terminus.

FIG 2

In vitro activities of colistin, LL37, WLBU2, and WR12 against 142 MDR/XDR clinical strains from CF (n = 100) and hospitalized (n = 42) patients. Shown are the mean MIC distributions against Gram-positive (A) and Gram-negative (B) bacterial isolates. **, statistically significant differences between the mean MICs of eCAPs (WLBU2 and WR12) and those of colistin and LL37 (P < 0.0001) using one-way analysis of variance (ANOVA) with multiple comparison tests; there are no significant differences between colistin and LL37 (P > 0.05).

FIG 3

(A) Selection of resistance invoked by rifampin, LL37, colistin, WR12, and WLBU2 by serial passages in MHB at 50% of their corresponding MIC, using three P. aeruginosa strains (PAO1 and two clinical isolates); the shaded areas indicate the development of resistance to the corresponding antimicrobial agents (fold MIC, ≥10). (B) Cross-resistance displayed by experimentally derived resistant strains. S, susceptible; R, resistant.