Lactoferricin inspired peptide AMC-109 augments the effect of ciprofloxacin against Pseudomonas aeruginosa biofilm in chronic murine wounds

Antimicrobial Peptides Demonstrate Activity against Resistant Bacterial Pathogens

The antimicrobial resistance crisis is an ongoing major threat to public health safety. Low- and middle-income countries are particularly susceptible to higher fatality rates and the economic impact of antimicrobial resistance (AMR). As an increasing number of pathogens emerge with multi- and pan-drug resistance to last-resort antibiotics, there is an urgent need to provide alternative antibacterial options to mitigate disease transmission, morbidity, and mortality. As identified by the World Health Organization (WHO), critically important pathogens such as Klebsiella and Pseudomonas species are becoming resistant to last-resort antibiotics including colistin while being frequently isolated from clinical cases of infection. Antimicrobial peptides are potent amino acid sequences produced by many life forms from prokaryotic, fungal, plant, to animal species. These peptides have many advantages, including their multi-hit mode of action, potency, and rapid onset of action with low levels of resistance being evident. These innate defense mechanisms also have an immune-stimulating action among other activities in vivo, thus making them ideal therapeutic options. Large-scale production and formulation issues (pharmacokinetics, pharmacodynamics), high cost, and protease instability hinder their mass production and limit their clinical application. This review outlines the potential of these peptides to act as therapeutic agents in the treatment of multidrug-resistant infections considering the mode of action, resistance, and formulation aspects. Clinically relevant Gram-positive and Gram-negative pathogens are highlighted according to the WHO priority pathogen list.

Synergistic Antimicrobial Action of Lactoferrin-Derived Peptides and Quorum Quenching Enzymes

Combined use of various antimicrobial peptides (AMPs) with enzymes that hydrolyze the signaling molecules of the resistance mechanism of various microorganisms, quorum sensing (QS), to obtain effective antimicrobials is one of the leading approaches in solving the antimicrobial resistance problem. Our study investigates the lactoferrin-derived AMPs, lactoferricin (Lfcin), lactoferampin and Lf(1-11), as potential partners for combination with enzymes hydrolyzing lactone-containing QS molecules, the hexahistidine-containing organophosphorus hydrolase (His6-OPH) and penicillin acylase, to obtain effective antimicrobial agents with a scope of practical application. The possibility of the effective combination of selected AMPs and enzymes was first investigated in silico using molecular docking method. Based on the computationally obtained results, His6-OPH/Lfcin combination was selected as the most suitable for further research. The study of physical-chemical characteristics of His6-OPH/Lfcin combination revealed the stabilization of enzymatic activity. A notable increase in the catalytic efficiency of action of His6-OPH in combination with Lfcin in the hydrolysis of paraoxon, N-(3-oxo-dodecanoyl)-homoserine lactone and zearalenone used as substrates was established. Antimicrobial efficiency of His6-OPH/Lfcin combination was determined against various microorganisms (bacteria and yeasts) and its improvement was observed as compared to AMP without enzyme. Thus, our findings demonstrate that His6-OPH/Lfcin combination is a promising antimicrobial agent for practical application.

Antimicrobial Peptide Mimics for Clinical Use: Does Size Matter?

The search for efficient antimicrobial therapies that can alleviate suffering caused by infections from resistant bacteria is more urgent than ever before. Infections caused by multi-resistant pathogens represent a significant and increasing burden to healthcare and society and researcher are investigating new classes of bioactive compounds to slow down this development. Antimicrobial peptides from the innate immune system represent one promising class that offers a potential solution to the antibiotic resistance problem due to their mode of action on the microbial membranes. However, challenges associated with pharmacokinetics, bioavailability and off-target toxicity are slowing down the advancement and use of innate defensive peptides. Improving the therapeutic properties of these peptides is a strategy for reducing the clinical limitations and synthetic mimics of antimicrobial peptides are emerging as a promising class of molecules for a variety of antimicrobial applications. These compounds can be made significantly shorter while maintaining, or even improving antimicrobial properties, and several downsized synthetic mimics are now in clinical development for a range of infectious diseases. A variety of strategies can be employed to prepare these small compounds and this review describes the different compounds developed to date by adhering to a minimum pharmacophore based on an amphiphilic balance between cationic charge and hydrophobicity. These compounds can be made as small as dipeptides, circumventing the need for large compounds with elaborate three-dimensional structures to generate simplified and potent antimicrobial mimics for a range of medical applications. This review highlight key and recent development in the field of small antimicrobial peptide mimics as a promising class of antimicrobials, illustrating just how small you can go.