A permeability-increasing drug synergizes with bacterial efflux pump inhibitors and restores susceptibility to antibiotics in multi-drug resistant Pseudomonas aeruginosa strains

Abstract

Resistance to antibiotics poses a major global threat according to the World Health Organization. Restoring the activity of existing drugs is an attractive alternative to address this challenge. One of the most efficient mechanisms of bacterial resistance involves the expression of efflux pump systems capable of expelling antibiotics from the cell. Although there are efflux pump inhibitors (EPIs) available, these molecules are toxic for humans. We hypothesized that permeability-increasing antimicrobial peptides (AMPs) could lower the amount of EPI necessary to sensitize bacteria to antibiotics that are efflux substrates. To test this hypothesis, we measured the ability of polymyxin B nonapeptide (PMBN), to synergize with antibiotics in the presence of EPIs. Assays were performed using planktonic and biofilm-forming cells of Pseudomonas aeruginosa strains overexpressing the MexAB-OprM efflux system. Synergy between PMBN and EPIs boosted azithromycin activity by a factor of 2,133 and sensitized P. aeruginosa to all tested antibiotics. This reduced several orders of magnitude the amount of inhibitor needed for antibiotic sensitization. The selected antibiotic-EPI-PMBN combination caused a 10 million-fold reduction in the viability of biofilm forming cells. We proved that AMPs can synergize with EPIs and that this phenomenon can be exploited to sensitize bacteria to antibiotics.

Synergistic activity of filtrates of Lactobacillus rhamnosus and Saccharomyces boulardii and antibacterial preparations against Corynebacterium spp.

“…Through the interaction of peptides, which increase permeability, with the outflow inhibitors due to the reduction of their number, increase in the sensitivity of bacteria is achieved. Thus, the increased sensitivity of P. aeruginosa to antibacterial drugs was established (Ferrer-Espada et al, 2019). These data are in good agreement with the presented results of our own research and prove the possibility of using biologically active substances to increase the sensitivity of bacteria to traditional antimicrobials.…”

“…They also affect the cell wall of bacteria, production enzymes, which results in suppression of the virulence of the pathogen (Ismeeal et al, 2013;Satpute et al, 2016). Other antimicrobials increase bacterial sensitivity to antibiotics by reducing the number of outflow inhibitors (efflux pump inhibitors capable of expelling antibiotics from the cell) (Van Bambeke et al, 2006;George et al, 2011;Li et al, 2015;Ferrer-Espada et al, 2019). Through the interaction of peptides, which increase permeability, with the outflow inhibitors due to the reduction of their number, increase in the sensitivity of bacteria is achieved.…”

“…A study was performed on planktonic and biofilm formation cells of Pseudomonas aeruginosa strains with overexpression. Increased antimicrobial activity of azithromycin against this pathogen has been demonstrated (Ferrer-Espada et al, 2019). Membraneactive macromolecules, as well as metabolites, produced by their own methods, not only destroy planktonic and biofuel types of bacteria, but also potentiate antibiotics (erythromycin and rifampicin).…”

Overcoming Intrinsic and Acquired Resistance Mechanisms Associated with the Cell Wall of Gram-Negative Bacteria

“…Similarly, the combination of a membrane permeabilising agent with an efflux pump inhibitor may have benefits in lowering EPI concentration to minimise cytotoxicity and potentiate a broader range of antibiotic agents that would otherwise have been sensitive to efflux. Utilising the EPI PAßN and the membrane permeabiliser PMBN, Ferrer-Espada et al were able to improve the activity of azithromycin by 2000-fold with 1 μg/mL PMBN [ 149 ]. Interestingly, this could not be achieved with the EPI alone [ 149 ].…”

“…Utilising the EPI PAßN and the membrane permeabiliser PMBN, Ferrer-Espada et al were able to improve the activity of azithromycin by 2000-fold with 1 μg/mL PMBN [ 149 ]. Interestingly, this could not be achieved with the EPI alone [ 149 ]. Ideally, if the right efflux pump inhibitor was developed, mammalian toxicity could be significantly reduced by lowering the dose required with compounds like PMBN.…”