Stapling of Peptides Potentiates the Antibiotic Treatment of Acinetobacter baumannii In Vivo.

Gina Schouten,Felix Paulussen,Wilbert Bitter,Oscar Kuipers,Tom Grossmann,Peter Van Ulsen

doi:10.3390/antibiotics11020273

Abstract

The rising incidence of multidrug resistance in Gram-negative bacteria underlines the urgency for novel treatment options. One promising new approach is the synergistic combination of antibiotics with antimicrobial peptides. However, the use of such peptides is not straightforward; they are often sensitive to proteolytic degradation, which greatly limits their clinical potential. One approach to increase stability is to apply a hydrocarbon staple to the antimicrobial peptide, thereby fixing them in an α-helical conformation, which renders them less exposed to proteolytic activity. In this work we applied several different hydrocarbon staples to two previously described peptides shown to act on the outer membrane, L6 and L8, and tested their activity in a zebrafish embryo infection model using a clinical isolate of Acinetobacter baumannii as a pathogen. We show that the introduction of such a hydrocarbon staple to the peptide L8 improves its in vivo potentiating activity on antibiotic treatment, without increasing its in vivo antimicrobial activity, toxicity or hemolytic activity.

Highlights

The widespread use of antibiotics has increased the selective pressure on bacteria to develop antibiotic resistance [1]
L6 and L8 have been suggested as peptides that synergistically increase the effect of vancomycin [30]
We first validated the effect of the potentiator peptides L6 and L8 on the growth of three clinical isolates of E. coli, A. baumannii and K. pneumoniae (Table 1), by adding them separately or in combination with vancomycin in checkerboard assays and determining the minimum inhibitory concentration (MIC) of the peptides, vancomycin and their combination

Summary

Introduction

The widespread use of antibiotics has increased the selective pressure on bacteria to develop antibiotic resistance [1]. This rise in resistance is problematic, because only a few novel antibiotics with a new mode-of-action have been approved in the last 30 years [2,3]. The three bacteria with the highest priority are multidrug-resistant Gram-negative bacteria; Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacteriaceae [8]. The number of pan-drug-resistant A. baumannii strains in particular is growing rapidly and renders it the pathogen with the highest priority for development of new treatments, because this adds to its ability to resist desiccation and to evade host immune defenses [10,11,12]

Methods

Results

Conclusion