scholarly journals Role of efflux pump(s) in intrinsic resistance of Pseudomonas aeruginosa: active efflux as a contributing factor to beta-lactam resistance.

1994 ◽  
Vol 38 (8) ◽  
pp. 1742-1752 ◽  
Author(s):  
X Z Li ◽  
D Ma ◽  
D M Livermore ◽  
H Nikaido
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Beta Lactam ◽  
Intrinsic Resistance ◽  
Active Efflux

scholarly journals MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

2021 ◽  
Vol 22 (10) ◽  
pp. 5328
Author(s):  
Miao Ma ◽  
Margaux Lustig ◽  
Michèle Salem ◽  
Dominique Mengin-Lecreulx ◽  
Gilles Phan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Cell Division ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

scholarly journals The polyaminoisoprenyl potentiator NV716 revives old disused antibiotics against intracellular forms of infection by Pseudomonas aeruginosa

2020 ◽  
pp. AAC.02028-20
Author(s):  
Gang W. Wang ◽  
Jean-Michel Brunel ◽  
Jean-Michel Bolla ◽  
Françoise Van Bambeke
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Hill Equation ◽  
Intrinsic Resistance ◽  
Bacterial Persistence ◽  
Response Curves ◽  
Active Efflux ◽  
Efflux Pump Inhibitors ◽  
The Hill ◽  
Multiple Antibiotics

Active efflux confers intrinsic resistance to multiple antibiotics in Pseudomonas aeruginosa, including old disused molecules. Beside resistance, intracellular survival is another reason for failure to eradicate bacteria with antibiotics. We evaluated the capacity of polyaminoisoprenyl potentiators (designed as efflux pump inhibitors [EPIs]) NV716 and NV731 compared to PAβN to restore the activity of disused antibiotics (doxycycline, chloramphenicol [substrates for efflux], rifampin [not substrate]) in comparison with ciprofloxacin against intracellular P. aeruginosa (strains with variable efflux levels) in THP-1 monocytes exposed during 24h to antibiotics alone (0.003-100x MIC) or combined with EPIs. Pharmacodynamic parameters (apparent static concentrations [Cs]; maximal relative efficacy [Emax]) were calculated using the Hill equation of concentration-response curves. PAβN and NV731 moderately reduced (0-4 doubling dilutions) antibiotic MICs but did not affect their intracellular activity. NV716 markedly reduced (1-16 doubling dilutions) the MIC of all antibiotics (substrates or not for efflux; strains expressing efflux or not); it improved their relative potency and maximal efficacy (lower Cs; more negative Emax) intracellularly. In parallel, NV716 reduced the persister fraction in stationary cultures when combined with ciprofloxacin. In contrast to PAβN and NV731 that act as EPIs against extracellular bacteria only, NV716 can resensitize P. aeruginosa to antibiotics whether substrates or not for efflux, both extracellularly and intracellularly. This suggests a complex mode of action that goes beyond a simple inhibition of efflux and reduces bacterial persistence. NV716 may appear as a useful adjuvant, including to disused antibiotics with low antipseudomonal activity, to improve their activity, including against intracellular P. aeruginosa.

Limited contribution of the outer-membrane penetration barrier towards intrinsic antibiotic resistance in Pseudomonas aeruginosa

1982 ◽  
Vol 28 (2) ◽  
pp. 169-175 ◽  
Author(s):  
R. Allan Scudamore ◽  
Morris Goldner
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Growth Curves ◽  
Beta Lactam ◽  
Intrinsic Resistance ◽  
Beta Lactam Antibiotics ◽  
High Level

The role of the outer membrane (OM) was investigated in relation to the high level of intrinsic antibiotic resistance of Pseudomonas aeruginosa ATCC 9027. OM penetration barriers were measured by comparing turbidimetric growth curves of EDTA-treated and normal cells exposed to carbenicillin, moxalactam (LY 127935), gentamicin, tobramycin, rifampin, novobiocin, and vancomycin. OM barriers were also measured for carbenicillin and moxalactam in P. aeruginosa strain K 799/61, a hypersusceptible mutant presumed to have lost its penetration barrier in the cell envelope. Most antibiotics penetrated the OM efficiently and there was little difference between the two strains. The evidence therefore suggests that intrinsic resistance of P. aeruginosa, especially to the beta-lactam antibiotics, is not mainly due to the OM. A penetration barrier situated deeper within the cell envelope is hypothesized, the size of which in relation to any antibiotic may be estimated by comparing the IC50 values of EDTA-treated cells of the two strains.

scholarly journals Involvement of an Active Efflux System in the Natural Resistance of Pseudomonas aeruginosa to Aminoglycosides

1999 ◽  
Vol 43 (11) ◽  
pp. 2624-2628 ◽  
Author(s):  
Julio Ramos Aires ◽  
Thilo Köhler ◽  
Hiroshi Nikaido ◽  
Patrick Plésiat
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Regulatory Gene ◽  
Natural Resistance ◽  
Insertion Mutagenesis ◽  
Detectable Effect ◽  
Efflux System ◽  
Intrinsic Resistance ◽  
Cloning And Sequencing ◽  
Active Efflux ◽  
Energy Dependent

ABSTRACT A mutant, named 11B, hypersusceptible to aminoglycosides, tetracycline, and erythromycin was isolated after Tn501insertion mutagenesis of Pseudomonas aeruginosa PAO1. Cloning and sequencing experiments showed that 11B was deficient in an, at that time, unknown active efflux system that contains homologs of MexAB. This locus also contained a putative regulatory gene,mexZ, transcribed divergently from the efflux operon. Introduction of a recombinant plasmid that carries the genes of the efflux system restored the resistance of 11B to parental levels, whereas overexpression of these genes strongly increased the MICs of substrate antibiotics for the PAO1 host. Antibiotic accumulation studies confirmed that this new system is an energy-dependent active efflux system that pumps out aminoglycosides. Furthermore, this system appeared to function with an outer membrane protein, OprM. While the present paper was being written and reviewed, genes with a sequence identical to our pump genes, mexXY of P. aeruginosa, have been reported to increase resistance to erythromycin, fluoroquinolones, and organic cations inEscherichia coli hosts, although efflux of aminoglycosides was not examined (Mine et al., Antimicrob. Agents Chemother. 43:415–417, 1999). Our study thus shows that the MexXY system plays an important role in the intrinsic resistance of P. aeruginosato aminoglycosides. Although overexpression of MexXY increased the level of resistance to fluoroquinolones, disruption of themexXY operon in P. aeruginosa had no detectable effect on susceptibility to these agents.

scholarly journals Pseudomonas aeruginosa Polynucleotide Phosphorylase Controls Tolerance to Aminoglycoside Antibiotics by Regulating the MexXY Multidrug Efflux Pump

2020 ◽  
Author(s):  
Zheng Fan ◽  
Xiaolei Pan ◽  
Dan Wang ◽  
Ronghao Chen ◽  
Tongtong Fu ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Resistance ◽  
Efflux Pump ◽  
Opportunistic Pathogen ◽  
Aminoglycoside Antibiotics ◽  
Polynucleotide Phosphorylase ◽  
Multidrug Efflux ◽  
Intrinsic Resistance ◽  
Multidrug Efflux Pump ◽  
Fluoroquinolone Antibiotics

Pseudomonas aeruginosa is an opportunistic pathogen that shows high intrinsic resistance to a variety of antibiotics. The MexX-MexY-OprM efflux pump plays an important role in the bacterial resistance to aminoglycoside antibiotics. Polynucleotide phosphorylase (PNPase) is a highly conserved exonuclease that plays important roles in RNA processing and bacterial response to environmental stresses. Previously, we demonstrated that PNPase controls the tolerance to fluoroquinolone antibiotics by influencing the production of pyocin in P. aeruginosa. In this study, we found that mutation of the PNPase coding gene (pnp) in P. aeruginosa increases the bacterial tolerance to aminoglycoside antibiotics. We further demonstrate that upregulation of the mexXY genes is responsible for the increased tolerance in the pnp mutant. Furthermore, our experimental results revealed that PNPase controls translation of the armZ mRNA through its 5′ untranslated region (5′-UTR). ArmZ had previously been shown to positively regulate the expression of mexXY. Therefore, our results revealed a novel role of PNPase in the regulation of armZ and subsequently the MexXY efflux pump.

scholarly journals Role of the AheABC Efflux Pump in Aeromonas hydrophila Intrinsic Multidrug Resistance

2008 ◽  
Vol 52 (4) ◽  
pp. 1559-1563 ◽  
Author(s):  
Mathieu Hernould ◽  
Séverine Gagné ◽  
Michel Fournier ◽  
Claudine Quentin ◽  
Corinne Arpin
Keyword(s):  
Multidrug Resistance ◽  
Aeromonas Hydrophila ◽  
Efflux Pump ◽  
Gene Inactivation ◽  
Multidrug Efflux ◽  
Intrinsic Resistance

ABSTRACT Gene inactivation and complementation experiments showed that the tripartite AheABC efflux pump of Aeromonas hydrophila extruded at least 13 substrates, including nine antibiotics. The use of phenylalanine-arginine-β-naphthylamide (PAβN) revealed an additional system(s) contributing to intrinsic resistance. This is the first analysis of the role of multidrug efflux systems in Aeromonas spp.

scholarly journals Antibiotic Resistance in Pseudomonas aeruginosa Strains with Increased Mutation Frequency Due to Inactivation of the DNA Oxidative Repair System

2009 ◽  
Vol 53 (6) ◽  
pp. 2483-2491 ◽  
Author(s):  
L. F. Mandsberg ◽  
O. Ciofu ◽  
N. Kirkby ◽  
L. E. Christiansen ◽  
H. E. Poulsen ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Polymorphonuclear Leukocytes ◽  
Oxidative Dna Damage ◽  
Efflux Pump ◽  
Repair System ◽  
High Frequencies ◽  
Resistance To Antibiotics ◽  
Development Of Resistance

ABSTRACT The chronic Pseudomonas aeruginosa infection of the lungs of cystic fibrosis (CF) patients is characterized by the biofilm mode of growth and chronic inflammation dominated by polymorphonuclear leukocytes (PMNs). A high percentage of P. aeruginosa strains show high frequencies of mutations (hypermutators [HP]). P. aeruginosa is exposed to oxygen radicals, both those generated by its own metabolism and especially those released by a large number of PMNs in response to the chronic CF lung infection. Our work therefore focused on the role of the DNA oxidative repair system in the development of HP and antibiotic resistance. We have constructed and characterized mutT, mutY, and mutM mutants in P. aeruginosa strain PAO1. The mutT and mutY mutants showed 28- and 7.5-fold increases in mutation frequencies, respectively, over that for PAO1. These mutators had more oxidative DNA damage (higher levels of 7,8-dihydro-8-oxodeoxyguanosine) than PAO1 after exposure to PMNs, and they developed resistance to antibiotics more frequently. The mechanisms of resistance were increased β-lactamase production and overexpression of the MexCD-OprJ efflux-pump. Mutations in either the mutT or the mutY gene were found in resistant HP clinical isolates from patients with CF, and complementation with wild-type genes reverted the phenotype. In conclusion, oxidative stress might be involved in the development of resistance to antibiotics. We therefore suggest the possible use of antioxidants for CF patients to prevent the development of antibiotic resistance.

scholarly journals Role of efflux pump inhibitor in decreasing antibiotic cross-resistance of Pseudomonas aeruginosa in a burn hospital in Iran

2016 ◽  
Vol 10 (06) ◽  
pp. 600-604 ◽  
Author(s):  
Mahshid Talebi-Taher ◽  
َAli Majidpour ◽  
Abbas Gholami ◽  
Samira Rasouli-Kouhi ◽  
Maryam Adabi
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Cross Resistance ◽  
Beta Lactams ◽  
Efflux Pump Inhibitor ◽  
Efflux Pump Inhibitors

Introduction: Multidrug resistance in Pseudomonas aeruginosa may be due to efflux pump overexpression. This study phenotypically examined the role of efflux pump inhibitors in decreasing antibiotic cross-resistance between beta-lactams, fluoroquinolones, and aminoglycosides in P. aeruginosa isolates from burn patients in Iran. Methodology: A total of 91 phenotypically and genotypically confirmed P. aeruginosa samples were studied. Multidrug cross-resistance was determined using the disk diffusion method and minimum inhibitory concentration (MIC) test. The contribution of efflux pumps was determined by investigating MIC reduction assay to markers of beta-lactams, fluoroquinolones, and aminoglycosides in the absence and presence of an efflux pump inhibitor. All the isolates were also tested by polymerase chain reaction for the presence of mexA, mexC, and mexE efflux genes. Results: Of the isolates, 81 (89%) and 83 (91.2%) were multidrug resistant according to the disk diffusion and MIC method, respectively. Cross-resistance was observed in 67 (73.6%) and 68 (74.7%) of isolates according to the disk diffusion and MIC method, respectively. In the presence of the efflux pump inhibitor, twofold or higher MIC reduction to imipenem, cefepime, ciprofloxacin, and gentamicin was observed in 59, 65, 55, and 60 isolates, respectively. Except for two isolates that were negative for mexC, all isolates were positive for mexA, mexC, and mexE genes simultaneously. Conclusion: Efflux pumps could cause different levels of resistance based on their expression in clinical isolates. Early detection of different efflux pumps in P. aeruginosa could allow the use of other antibiotics and efflux pump inhibitors in combination with antibiotic therapy.

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