Dataset Information

The efflux inhibitor phenylalanine-arginine beta-naphthylamide (PA?N) permeabilizes the outer membrane of gram-negative bacteria.

ABSTRACT: Active efflux of antimicrobial agents is a primary mechanism by which bacterial pathogens can become multidrug resistant. The combined use of efflux pump inhibitors (EPIs) with pump substrates is under exploration to overcome efflux-mediated multidrug resistance. Phenylalanine-arginine ?-naphthylamide (PA?N) is a well-studied EPI that is routinely combined with fluoroquinolone antibiotics, but few studies have assessed its utility in combination with ?-lactam antibiotics. The initial goal of this study was to assess the efficacy of ?-lactams in combination with PA?N against the opportunistic pathogen, Pseudomonas aeruginosa. PA?N reduced the minimal inhibitory concentrations (MICs) of several ?-lactam antibiotics against P. aeruginosa; however, the susceptibility changes were not due entirely to efflux inhibition. Upon PA?N treatment, intracellular levels of the chromosomally-encoded AmpC ?-lactamase that inactivates ?-lactam antibiotics were significantly reduced and AmpC levels in supernatants correspondingly increased, potentially due to permeabilization of the outer membrane. PA?N treatment caused a significant increase in uptake of 8-anilino-1-naphthylenesulfonic acid, a fluorescent hydrophobic probe, and sensitized P. aeruginosa to bulky antibiotics (e.g. vancomycin) that are normally incapable of crossing the outer membrane, as well as to detergent-like bile salts. Supplementation of growth media with magnesium to stabilize the outer membrane increased MICs in the presence of PA?N and restored resistance to vancomycin. Thus, PA?N permeabilizes bacterial membranes in a concentration-dependent manner at levels below those typically used in combination studies, and this additional mode of action should be considered when using PA?N as a control for efflux studies.

SUBMITTER: Lamers RP

PROVIDER: S-EPMC3609863 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The efflux inhibitor phenylalanine-arginine beta-naphthylamide (PAβN) permeabilizes the outer membrane of gram-negative bacteria.

Lamers Ryan P RP Cavallari Joseph F JF Burrows Lori L LL

PloS one 20130327 3

Active efflux of antimicrobial agents is a primary mechanism by which bacterial pathogens can become multidrug resistant. The combined use of efflux pump inhibitors (EPIs) with pump substrates is under exploration to overcome efflux-mediated multidrug resistance. Phenylalanine-arginine β-naphthylamide (PAβN) is a well-studied EPI that is routinely combined with fluoroquinolone antibiotics, but few studies have assessed its utility in combination with β-lactam antibiotics. The initial goal of thi ...[more]

PMID: 23544160

Similar Datasets

Project description:BackgroundMultidrug-resistant (MDR) bacteria remain a major cause of morbidity and mortality globally. The present study was designed to investigate the in vitro antibacterial activities of crude methanol extract and constituents isolated by Column Chromatography (CC) from Cassia sieberiana bark (CSB) against ten MDR Gram-negative bacteria, as well as the mechanisms of action of the most active sample.MethodsThe antibacterial activity of the tested samples (extract, the fractions and their compounds isolated by CC and the structures obtained by exploiting 1H and 13C Nuclear magnetic resonance (NMR) spectra) in the presence and absence of an efflux pumps inhibitor, phenylalanine-arginine β-naphthylamide (PAβN), was evaluated using the micro-dilution method. The effects of the most active sample were evaluated on the cell growth kinetic and on the bacterial H+-ATPase proton pumps.ResultsPhytochemical composition of the crude extract showed a rather selective distribution of secondary metabolites (presence of polyphenols, tannins, steroids, triterpenes, flavonoids, alkaloids, saponins and absence of anthocyanins, anthraquinones). The tested samples displayed different antibacterial activities with minimal inhibitory concentrations (MICs) ranging from 64 to 512 μg/mL. Crude extract (CS) and fraction CSc showed the highest inhibitory spectra, both inhibiting all of the studied bacteria except Enterobacter aerogenes EA27 strain. Fraction CSc exerted bactericidal effects on most bacteria meanwhile, crude extract (CS) and sub-fraction CSc2 exerted bacteriostatic effects. Compounds 1 (spectaline) and 2 (iso-6-cassine) inhibited the growth of 70% (Escherichia coli ATCC8739 and AG102, Klebsiella pneumoniae ATCC11296, Enterobacter aerogenes ATCC13048 and EA27, Providencia stuartii ATCC29916, Pseudomonas aeruginosa PA01) and 60% (Escherichia coli ATCC8739, Klebsiella pneumoniae ATCC11296 and KP55, Providencia stuartii ATCC29916, Pseudomonas aeruginosa PA01 and PA124) of bacteria respectively with MICs ranging from 128 to 512 μg/mL. In the presence of PAβN, the activities of crude extract CS, fraction CAc and sub-fraction CSc2 strongly increased on most bacteria strains as their MICs significantly decreased. Sub-fraction CSc2 inhibited the H+-ATPase proton pumps and altered growth kinetic of Escherichia coli ATCC8739.ConclusionThe overall results justify the traditional use of C. sieberiana for the treatment of bacterial infections.

Dataset Information

The efflux inhibitor phenylalanine-arginine beta-naphthylamide (PA?N) permeabilizes the outer membrane of gram-negative bacteria.

Publications

The efflux inhibitor phenylalanine-arginine beta-naphthylamide (PAβN) permeabilizes the outer membrane of gram-negative bacteria.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets