Characterization, mechanism of action and optimization of activity of a novel peptide-peptoid hybrid against bacterial pathogens involved in canine skin infections

Ines Greco,Paul R Hansen,Luca Guardabassi,Peter Damborg,Natalia Molchanova,Alberto Oddo,Agnete Plahn Emborg,Bimal Jana

doi:10.1038/s41598-019-39042-3

Abstract

Integumentary infections like pyoderma represent the main reason for antimicrobial prescription in dogs. Staphylococcus pseudintermedius and Pseudomonas aeruginosa are frequently identified in these infections, and both bacteria are challenging to combat due to resistance. To avoid use of important human antibiotics for treatment of animal infections there is a pressing need for novel narrow-spectrum antimicrobial agents in veterinary medicine. Herein, we characterize the in vitro activity of the novel peptide-peptoid hybrid B1 against canine isolates of S. pseudintermedius and P. aeruginosa. B1 showed potent minimum inhibitory concentrations (MICs) against canine S. pseudintermedius and P. aeruginosa isolates as well rapid killing kinetics. B1 was found to disrupt the membrane integrity and affect cell-wall synthesis in methicillin-resistant S. pseudintermedius (MRSP). We generated 28 analogues of B1, showing comparable haemolysis and MICs against MRSP and P. aeruginosa. The most active analogues (23, 26) and B1 were tested against a collection of clinical isolates from canine, of which only B1 showed potent activity. Our best compound 26, displayed activity against P. aeruginosa and S. pseudintermedius, but not the closely related S. aureus. This work shows that design of target-specific veterinary antimicrobial agents is possible, even species within a genus, and deserves further exploration.

Highlights

Integumentary infections like pyoderma represent the main reason for antimicrobial prescription in dogs
The aim of the present study was to investigate the antimicrobial activity of B1 against a large collection of S. pseudintermedius and P. aeruginosa isolates from canine infections, determine time-kill kinetics and probe the mechanism of action against S. pseudintermedius
A similar but www.nature.com/scientificreports slightly inferior effect was detected against the clinical strain P. aeruginosa 26314, which was killed at 4x minimum inhibitory concentrations (MICs) in 2 h and at 2x MIC in 24 h (Fig. 2b)

Summary

Introduction

Integumentary infections like pyoderma represent the main reason for antimicrobial prescription in dogs. Staphylococcus pseudintermedius is a commensal bacterium colonizing dog skin and mucosal sites[1], and it is the predominant cause of canine pyoderma and otitis externa[2] These common infections represent the main reason for antimicrobial prescription in dogs[3]. Methicillin-resistant S. pseudintermedius (MRSP) has been reported worldwide[4], including sporadic infections in humans in contact with dogs[5,6] Pseudomonas aeruginosa is another pathogen frequently involved in canine integumentary infections, in particular otitis externa[7]. AMPs are present in all multicellular organisms as part of their innate immune systems[13] They show selective toxicity towards bacteria, rapid killing, broad-spectrum antimicrobial activity, and are active at micromolar concentrations or lower[14]. This study demonstrates that design of peptide-based antimicrobials which target specific veterinary bacterial species is possible

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Conclusion