scholarly journals Mode of action of the 2-phenylquinoline efflux inhibitor PQQ4R againstEscherichia coli

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3168 ◽  
Author(s):  
Diana Machado ◽  
Laura Fernandes ◽  
Sofia S. Costa ◽  
Rolando Cannalire ◽  
Giuseppe Manfroni ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Synergistic Activity ◽  
Dependent Manner ◽  
Gram Negative ◽  
E Coli ◽  
Efflux Pump Inhibitors

Efflux pump inhibitors are of great interest since their use as adjuvants of bacterial chemotherapy can increase the intracellular concentrations of the antibiotics and assist in the battle against the rising of antibiotic-resistant bacteria. In this work, we have described the mode of action of the 2-phenylquinoline efflux inhibitor (4-(2-(piperazin-1-yl)ethoxy)-2-(4-propoxyphenyl) quinolone – PQQ4R), againstEscherichia coli,by studding its efflux inhibitory ability, its synergistic activity in combination with antibiotics, and compared its effects with the inhibitors phenyl-arginine-β-naphthylamide (PAβN) and chlorpromazine (CPZ). The results showed that PQQ4R acts synergistically, in a concentration dependent manner, with antibiotics known to be subject to efflux inE. colireducing their MIC in correlation with the inhibition of their efflux. Real-time fluorometry assays demonstrated that PQQ4R at sub-inhibitory concentrations promote the intracellular accumulation of ethidium bromide inhibiting its efflux similarly to PAβN or CPZ, well-known and described efflux pump inhibitors for Gram-negative bacteria and whose clinical usage is limited by their levels of toxicity at clinical and bacteriological effective concentrations. The time-kill studies showed that PQQ4R, at bactericidal concentrations, has a rapid antimicrobial activity associated with a fast decrease of the intracellular ATP levels. The results also indicated that the mode of action of PQQ4R involves the destabilization of theE. coliinner membrane potential and ATP production impairment, ultimately leading to efflux pump inhibition by interference with the energy required by the efflux systems. At bactericidal concentrations, membrane permeabilization increases and finally ATP is totally depleted leading to cell death. Since drug resistance mediated by the activity of efflux pumps depends largely on the proton motive force (PMF), dissipaters of PMF such as PQQ4R, can be regarded as future adjuvants of conventional therapy againstE. coliand other Gram-negative bacteria, especially their multidrug resistant forms. Their major limitation is the high toxicity for human cells at the concentrations needed to be effective against bacteria. Their future molecular optimization to improve the efflux inhibitory properties and reduce relative toxicity will optimize their potential for clinical usage against multi-drug resistant bacterial infections due to efflux.

Human glucose-dependent insulinotropic polypeptide (GIP) is an antimicrobial adjuvant re-sensitising multidrug-resistant Gram-negative bacteria

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Da’san M. M. Jaradat ◽  
Nehaya Al-Karablieh ◽  
Basmah H. M. Zaarer ◽  
Wenyi Li ◽  
Khalil K.Y. Saleh ◽  
...  
Keyword(s):  
Efflux Pump ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
Low Concentrations ◽  
Bacterial Mutants ◽  
Drug Efflux Pumps ◽  
Gastrointestinal Peptides

Abstract Increasing antibiotic resistance in Gram-negative bacteria has mandated the development of both novel antibiotics and alternative therapeutic strategies. Evidence of interplay between several gastrointestinal peptides and the gut microbiota led us to investigate potential and broad-spectrum roles for the incretin hormone, human glucose-dependent insulinotropic polypeptide (GIP) against the Enterobacteriaceae bacteria, Escherichia coli and Erwinia amylovora. GIP had a potent disruptive action on drug efflux pumps of the multidrug resistant bacteria E. coli TG1 and E. amylovora 1189 strains. The effect was comparable to bacterial mutants lacking the inner and outer membrane efflux pump factor proteins AcrB and TolC. While GIP was devoid of direct antimicrobial activity, it has a potent membrane depolarizing effect, and at low concentrations, it significantly potentiated the activity of eight antibiotics and bile salt by reducing MICs by 4-8-fold in E. coli TG1 and 4-20-fold in E. amylovora 1189. GIP can thus be regarded as an antimicrobial adjuvant with potential for augmenting the available antibiotic arsenal.

scholarly journals Antibacterial activity of ethanolic leaf extract of Aquilaria malaccensis against multidrug-resistant Gram-negative pathogen

Food Research ◽  
2020 ◽  
Vol 4 (6) ◽  
pp. 1962-1968
Author(s):  
N.I.M. Jihadi ◽  
Y.Z.H-Y. Hashim ◽  
N.A. Rahim ◽  
K.M. Kamal ◽  
N.M. Noor ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Infections ◽  
Leaf Extract ◽  
Diffusion Method ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
Aquilaria Malaccensis ◽  
Crude Leaf Extract

The rapid emergence of resistant Gram-negative bacteria and the limited discovery of novel antibiotic is a global healthcare challenge. Many medicinal plants with potent bioactivities have been developed for the treatment of bacterial infections. Aquilaria malaccensis exhibits wide applications from perfumes and aromatic foods ingredients and great potential in medicines. In this study, crude leaf extract of A. malaccensis was evaluated for its antibacterial activity against several pathogenic Gram-negative bacteria. The leaves were processed and extracted by Soxhlet method using ethanol as the solvent. The antibacterial activity of the crude extract was tested by disc diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Acinetobacter baumannii (ATCC 19606), Klebsiella pneumoniae (ATCC 10031 and ATCC 700603) and Escherichia coli (ATCC 1129). Using the optimized method, the Soxhlet extract produced a yield of 178.41 mg/g. Treatment of the extract at 200 mg/mL displayed the largest inhibition zones of 14.0 mm and 9.7 mm against A. baumannii and K. pneumoniae ATCC 10031, respectively. In contrast, against E. coli and K. pneumoniae ATCC 700603, smaller zones of inhibitions of 3.3 mm were demonstrated. The MIC values of the extract were 32 mg/mL against A. baumannii and K. pneumoniae ATCC 10031 and 64 mg/mL against E. coli and K. pneumoniae ATCC 700603. The MBC values of the extract were consistent with the MIC values for all the bacteria investigated. Overall, this study was the first to show antibacterial activity of A. malaccensis leaves extract particularly against A. baumannii and K. pneumoniae and potentially develop for the treatment of resistant bacteria.

Conformational study of (Z)-5-(4-chlorobenzylidene)-2-[4-(2-hydroxyethyl)piperazin-1-yl]-3H-imidazol-4(5H)-one in different environments: insight into the structural properties of bacterial efflux pump inhibitors

2017 ◽  
Vol 73 (12) ◽  
pp. 1151-1157 ◽  
Author(s):  
Ewa Żesławska ◽  
Wojciech Nitek ◽  
Jadwiga Handzlik
Keyword(s):  
Multidrug Resistance ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Carboxylate Group ◽  
Piperazine Ring ◽  
Gram Negative ◽  
Efflux Pump Inhibitors

The 2-amine derivatives of 5-arylidene-3H-imidazol-4(5H)-one are a new class of bacterial efflux pump inhibitors, the chemical compounds that are able to restore antibiotic efficacy against multidrug resistant bacteria. 5-Arylidene-3H-imidazol-4(5H)-ones with a piperazine ring at position 2 reverse the mechanisms of multidrug resistance (MDR) of the particularly dangerous Gram-negative bacteria E. coli by inhibition of the efflux pump AcrA/AcrB/TolC (a main multidrug resistance mechanism in Gram-negative bacteria, consisting of a membrane fusion protein, AcrA, a Resistant-Nodulation-Division protein, AcrB, and an outer membrane factor, TolC). In order to study the influence of the environment on the conformation of (Z)-5-(4-chlorobenzylidene)-2-[4-(2-hydroxyethyl)piperazin-1-yl]-3H-imidazol-4(5H)-one, (3), two different salts were prepared, namely with picolinic acid {systematic name: 4-[(Z)-4-(4-chlorobenzylidene)-5-oxo-3,4-dihydro-1H-imidazol-2-yl]-1-(2-hydroxyethyl)piperazin-1-ium pyridine-2-carboxylate, C16H20ClN4O2 +·C6H4NO2 −, (3 a )} and 4-nitrophenylacetic acid {systematic name: 4-[(Z)-4-(4-chlorobenzylidene)-5-oxo-3,4-dihydro-1H-imidazol-2-yl]-1-(2-hydroxyethyl)piperazin-1-ium 2-(4-nitrophenyl)acetate, C16H20ClN4O2 +·C8H6NO4 −, (3 b )}. The crystal structures of the new salts were determined by X-ray diffraction. In both crystal structures, the molecule of (3) is protonated at an N atom of the piperazine ring by proton transfer from the corresponding acid. The carboxylate group of picolinate engages in hydrogen bonds with three molecules of the cation of (3), whereas the carboxylate group of 4-nitrophenylacetate engages in hydrogen bonds with only two molecules of (3). As a consequence of these interactions, different orientations of the hydroxyethyl group of (3) are observed. The crystal structures are additionally stabilized by both C—H...N [in (3 a )] and C—H...O [in (3 a ) and (3 b )] intermolecular interactions. The geometry of the imidazolone fragment was compared with other crystal structures possessing this moiety. The tautomer observed in the crystal structures presented here, namely 3H-imidazol-4(5H)-one [systematic name: 1H-imidazol-5(4H)-one], is also that most frequently observed in other structures containing this heterocycle.

scholarly journals BioSAXS measurements reveal that two antimicrobial peptides induce similar molecular changes in Gram-negative and Gram-positive bacteria

2019 ◽  
Author(s):  
A.R. von Gundlach ◽  
M. Ashby ◽  
J. Gani ◽  
P. M. Lopez-Perez ◽  
A. Cookson ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Mode Of Action ◽  
Bacterial Load ◽  
Ultrastructural Changes ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria

AbstractTwo highly active short broad-spectrum AMPs (14D and 69D) with unknown mode of action have been investigated in regards to their effect against the Gram-negative bacteriaE. coliand the Gram-positive bacteria methicillin-resistantStaphylococcus aureus(MRSA). Minimal inhibitory concentration (MIC) measurements using a cell density of 108cfu/ml resulted in values between 16 and 32 μg/ml. Time kill experiments using 108cfu/ml revealed complete killing, except for 69D in combination with MRSA, where bacterial load was reduced a million times. Small angle X-ray scattering of biological samples (BioSAXS) at 108cfu/ml was applied to investigate the ultrastructural changes inE. coliand MRSA in response to these two broad-spectrum AMPs. In addition, electron microscopy (EM) was performed to visualize the treated and non-treated bacteria. As expected, the scattering curves generated using BioSAXS show the ultrastructure of the Gram-positive and Gram-negative bacteria to be very different (BioSAXS is not susceptible to the outer shape). After treatment with either peptide, the scattering curves ofE. coliand MRSA cells are much more alike. This data in conjunction with the EM indicates that ribosomes might be effected by the treatment as well as changes in the nucleoid occurs. Whereas in EM it is notoriously difficult to observe changes for spherical Gram-positives, the BioSAXS results are superior and reveal strongly similar effects for both peptides induced in Gram-positive as well as Gram-negative bacteria. Given the high-throughput possibility and robust statistics BioSAXS can support and speed up mode of action research in AMPs and other antimicrobial compounds, making a contribution towards the development of urgently needed drugs against resistant bacteria.

scholarly journals An overview of carbapenem, its resistance and therapeutic options for infections caused by carbapenem resistant bacteria

2020 ◽  
Vol 9 (9) ◽  
pp. 1454
Author(s):  
Hari P. Nepal ◽  
Rama Paudel
Keyword(s):  
Bacterial Infections ◽  
Carbapenem Resistance ◽  
Therapeutic Options ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Beta Lactam ◽  
Gram Negative ◽  
Penicillin Binding Proteins ◽  
Carbapenem Resistant ◽  
The World

Carbapenems are beta-lactam drugs that have broadest spectrum of activity. They are commonly used as the drugs of last resort to treat complicated bacterial infections. They bind to penicillin binding proteins (PBPs) and inhibit cell wall synthesis in bacteria. Important members that are in clinical use include doripenem, ertapenem, imipenem, and meropenem. Unlike other members, imipenem is hydrolyzed significantly by renal dehydropeptidase; therefore, it is administered together with an inhibitor of renal dehydropeptidase, cilastatin. Carbapenems are usually administered intravenously due to their low oral bioavailability. Most common side effects of these drugs include nausea, vomiting, diarrhea, skin rashes, and reactions at the infusion sites. Increasing resistance to these antibiotics is being reported throughout the world and is posing a threat to public health.  Primary mechanisms of carbapenem resistance include expulsion of drug and inactivation of the drug by production of carbapenemases which may not only hydrolyze carbapenem, but also cephalosporin, penicillin, and aztreonam. Resistance especially among Gram negative bacteria is of much concern since there are only limited therapeutic options available for infections caused by carbapenem resistant Gram-negative bacterial pathogens. Commonly used drugs to treat such infections include polymyxins, fosfomycin and tigecycline.

A Tobramycin Vector Enhances Synergy and Efficacy of Efflux Pump Inhibitors against Multidrug-Resistant Gram-Negative Bacteria

2017 ◽  
Vol 60 (9) ◽  
pp. 3913-3932 ◽  
Author(s):  
Xuan Yang ◽  
Sudeep Goswami ◽  
Bala Kishan Gorityala ◽  
Ronald Domalaon ◽  
Yinfeng Lyu ◽  
...  
Keyword(s):  
Efflux Pump ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Efflux Pump Inhibitors

scholarly journals Antibacterial and Antibiotic Modifying Potential of Crude Extracts, Fractions, and Compounds from Acacia polyacantha Willd. against MDR Gram-Negative Bacteria

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Flora T. Mambe ◽  
Jean Na-Iya ◽  
Ghislain W. Fotso ◽  
Fred Ashu ◽  
Bathélémy Ngameni ◽  
...  
Keyword(s):  
Oleanolic Acid ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Synergistic Effects ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Efflux Pump Inhibitor ◽  
Gram Negative ◽  
Acacia Polyacantha

The present study aimed to assess the in vitro antibacterial and antibiotic modifying activities of methanol extracts prepared from the leaf (APL) and bark (APB) of Acacia polyacantha, fractions (APLa-d) and compounds isolated from APL against a panel of multidrug resistant (MDR) Gram-negative bacteria. Leaf extract was subjected to column chromatography for compounds isolation; antibacterial assays were performed on samples alone and with an efflux pump inhibitor (EPI), respectively, and several antibiotics on the tested bacteria. The phytochemical investigation of APL led to the isolation of stigmasterol (1), β-amyrin (2), 3-O-β-D-glucopyranosylstigmasterol (3), 3-O-methyl-D-chiro-inositol (4), epicatechin (5), quercetin-3-O-glucoside (6), 3-O-[β-D-xylopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (7), and 3-O-[β-galactopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (8). APL and APB had minimal inhibitory concentration (MIC) values ≤ 1024 μg/mL on 73.3% and 46.7% of the tested bacteria, respectively. APLb and APLd were effective against 88.9% of tested bacterial species with compound 8 showing the highest activity inhibiting 88.9% of tested bacteria. The EPI, phenylalanine-arginine-β-naphthylamide (PAßN), strongly improved the activity of APL, APLb, APLd, and compound 8 on all tested bacteria. Synergistic effects were obtained when APL and compounds 7 and 8 were combined with erythromycin (ERY), gentamycin (GEN), ciprofloxacin (CIP), and norfloxacin (NOR). The present study demonstrates the antibacterial potential of Acacia polyacantha and its constituents to combat bacterial infections alone or in combination with EPI.

Escherichia coli tol and rcs genes participate in the complex network affecting curli synthesis

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2487-2497 ◽  
Author(s):  
Anne Vianney ◽  
Grégory Jubelin ◽  
Sophie Renault ◽  
Corine Dorel ◽  
Philippe Lejeune ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Membrane Integrity ◽  
Regulatory Proteins ◽  
Gram Negative Bacteria ◽  
Dependent Manner ◽  
Dominant Effect ◽  
Gram Negative ◽  
E Coli

Curli are necessary for the adherence of Escherichia coli to surfaces, and to each other, during biofilm formation, and the csgBA and csgDEFG operons are both required for their synthesis. A recent survey of gene expression in Pseudomonas aeruginosa biofilms has identified tolA as a gene activated in biofilms. The tol genes play a fundamental role in maintaining the outer-membrane integrity of Gram-negative bacteria. RcsC, the sensor of the RcsBCD phosphorelay, is involved, together with RcsA, in colanic acid capsule synthesis, and also modulates the expression of tolQRA and csgDEFG. In addition, the RcsBCD phosphorelay is activated in tol mutants or when Tol proteins are overexpressed. These results led the authors to investigate the role of the tol genes in biofilm formation in laboratory and clinical isolates of E. coli. It was shown that the adherence of cells was lowered in the tol mutants. This could be the result of a drastic decrease in the expression of the csgBA operon, even though the expression of csgDEFG was slightly increased under such conditions. It was also shown that the Rcs system negatively controls the expression of the two csg operons in an RcsA-dependent manner. In the tol mutants, activation of csgDEFG occurred via OmpR and was dominant upon repression by RcsB and RcsA, while these two regulatory proteins repressed csgBA through a dominant effect on the activator protein CsgD, thus affecting curli synthesis. The results demonstrate that the Rcs system, previously known to control the synthesis of the capsule and the flagella, is an additional component involved in the regulation of curli. Furthermore, it is shown that the defect in cell motility observed in the tol mutants depends on RcsB and RcsA.

scholarly journals Innolysins: A novel approach to engineer endolysins to kill Gram-negative bacteria

2018 ◽  
Author(s):  
Athina Zampara ◽  
Martine C. Holst Sørensen ◽  
Dennis Grimon ◽  
Fabio Antenucci ◽  
Yves Briers ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Receptor Binding ◽  
Binding Proteins ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Proof Of Concept ◽  
Gram Negative ◽  
E Coli ◽  
Phage Receptor ◽  
Alternative Antimicrobials

ABSTRACTBacteriophage-encoded endolysins degrading the essential peptidoglycan of bacteria are promising alternative antimicrobials to handle the global threat of antibiotic resistant bacteria. However, endolysins have limited use against Gram-negative bacteria, since their outer membrane prevents access to the peptidoglycan. Here we present Innolysins, a novel concept for engineering endolysins that allows the enzymes to pass through the outer membrane, hydrolyse the peptidoglycan and kill the target bacterium. Innolysins combine the enzymatic activity of endolysins with the binding capacity of phage receptor binding proteins (RBPs). As our proof of concept, we used phage T5 endolysin and receptor binding protein Pb5, which binds irreversibly to the phage receptor FhuA involved in ferrichrome transport inEscherichia coli. In total, we constructed twelve Innolysins fusing endolysin with Pb5 or the binding domain of Pb5 with or without flexible linkers in between. While the majority of the Innolysins maintained their muralytic activity, Innolysin#6 also showed bactericidal activity againstE. colireducing the number of bacteria by 1 log, thus overcoming the outer membrane barrier. Using anE. coli fhuAdeletion mutant, we demonstrated that FhuA is required for bactericidal activity, supporting that the specific binding of Pb5 to its receptor onE. coliis needed for the endolysin to access the peptidoglycan. Accordingly, Innolysin#6 was able to kill other bacterial species that carry conserved FhuA homologs such asShigella sonneiandPseudomonas aeruginosa. In summary, the Innolysin approach expands recent protein engineering strategies allowing customization of endolysins by exploiting phage RBPs to specifically target Gram-negative bacteria.IMPORTANCEThe extensive use of antibiotics has led to the emergence of antimicrobial resistant bacteria responsible for infections causing more than 50,000 deaths per year across Europe and the US. In response, the World Health Organization has stressed an urgent need to discover new antimicrobials to control in particular Gram-negative bacterial pathogens, due to their extensive multi-drug resistance. However, the outer membrane of Gram-negative bacteria limits the access of many antibacterial agents to their targets. Here, we developed a new approach, Innolysins that enable endolysins to overcome the outer membrane by exploiting the binding specificity of phage receptor binding proteins. As proof of concept, we constructed Innolysins againstE. coliusing the endolysin and the receptor binding protein of phage T5. Given the rich diversity of phage receptor binding proteins and their different binding specificities, our proof of concept paves the route for creating an arsenal of pathogen specific alternative antimicrobials.

scholarly journals Intravenous Immunoglobulin for Treating Bacterial Infections: One More Mechanism of Action

2019 ◽  
Author(s):  
Teiji Sawa ◽  
Mao Kinoshita ◽  
Keita Inoue ◽  
Junya Ohara ◽  
Kiyoshi Moriyama
Keyword(s):  
Bacterial Infections ◽  
Bacterial Toxin ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Drug Resistant Bacteria ◽  
Toxin Secretion ◽  
Dependent Cell ◽  
V Antigen

The mechanisms underlying the effects of γ-globulin therapy for bacterial infections are thought to involve bacterial cell lysis via complement activation, phagocytosis via bacterial opsonization, toxin neutralization, and antibody-dependent cell-mediated cytotoxicity. Nevertheless, recent advances in the study of pathogenicity in gram-negative bacteria have raised the possibility of an association between γ-globulin and bacterial toxin secretion. Over time, new toxin secretion systems like the type III secretion system have been discovered in many pathogenic gram-negative bacteria. With this system, the bacterial toxins are directly injected into the cytoplasm of the target cell through a special secretory apparatus without any exposure to the extracellular environment and, therefore, with no opportunity for antibodies to neutralize the toxin. However, because antibodies against the V-antigen, which is located on the needle-shaped tip of the bacterial secretion apparatus, can inhibit toxin translocation, this raises the hope that the toxin might be susceptible to antibody targeting. Because multi-drug resistant bacteria are now prevalent, inhibiting this secretion mechanism is attractive as an alternative or adjunctive therapy against lethal bacterial infections. Thus, it would not be unreasonable to define the blocking effect of anti-V-antigen antibodies as the fifth mechanism for immunoglobulin action against bacterial infections.

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