Cost Action BM0701 Atens

Brussels, Belgium

Cost Action BM0701 Atens

Brussels, Belgium
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Martins M.,New University of Lisbon | Martins M.,University College Dublin | Viveiros M.,New University of Lisbon | Couto I.,New University of Lisbon | And 6 more authors.
In Vivo | Year: 2011

Background/Aim: Bacterial multidrug resistance may be mediated by the overexpression of efflux pumps. Conventional evaluation of efflux activity using efflux pump substrates, such as ethidium bromide, requires specialised instrumentation. The agar-based method, previously reported, has been modified to evaluate as many as twelve bacterial strains and has been termed the ethidium bromide-agar cartwheel method. Materials and Methods: Agar plates containing different concentrations of ethidium bromide were swabbed with bacterial cultures. The cell efflux capacity increased with increasing ethidium bromide concentration, which produced fluorescence of the bacterial mass. Results: The method was shown to be useful for the detection of efflux activity among multidrug-resistant Gram-negative and Gram-positive clinical isolates, as confirmed by the determination of minimum inhibitory concentration for several antibiotics in the presence of known efflux pump inhibitors. Conclusion: This method may be adapted to the clinical laboratory for the presumptive identification of multidrug-resistant isolates that overexpress efflux pump systems.

Bolla J.-M.,Jean Moulin University Lyon 3 | Alibert-Franco S.,Jean Moulin University Lyon 3 | Handzlik J.,COST Action BM0701 ATENS | Handzlik J.,Jagiellonian University | And 7 more authors.
FEBS Letters | Year: 2011

In Gram-negative bacteria, the envelope is a sophisticated barrier protecting the cell against external toxic compounds. Membrane transporters, e.g., porins or efflux pumps, are main filters regulating the internal accumulation of various hydrophilic molecules. Regarding bacterial susceptibility towards antibacterial agents, membrane permeability is part of the early bacterial defense. The bacterium manages the translocation process, influx and efflux, to control the intracellular concentration of various molecules. Antibiotics and biocides are substrates of these mechanisms and the continuing emergence of multidrug resistant isolates is a growing worldwide health concern. Different strategies could be proposed to bypass the bacterial membrane barrier, comprising influx and efflux mechanisms, in order to restore the activity of antibiotics against resistant bacteria. © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Armada A.M.,New University of Lisbon | Alexandru T.,National Institute for Laser, Plasma and Radiation Physics | Machado D.,New University of Lisbon | Danko B.,University of Szeged | And 13 more authors.
In Vivo | Year: 2013

Chlorpromazine (CPZ) was exposed to a 266nm laser beam for different periods of time ranging from minutes to 24 h. At intervals, the products from irradiation were evaluated by thin-layer chromatography (TLC) and evaluated for their activity against mycobacteria of human interest (Mycobacterium tuberculosis, M. avium, M. intracellulare and their corresponding reference strains or clinical isolates). With the exception of the M. avium 47/07 clinical strain, the products produced from the irradiation of CPZ for 4 h had greater activity against M. intracellulare ATCC, M. avium ATCC, H37Rv and the Multidrug-resistant tuberculosis (MDRTB) strains as opposed to that produced by the unirradiated control. The level of products from the 4-h exposure of CPZ remained the same throughout the next 20 h of irradiation. Of significant note is that the irradiation products of CPZ had lower in vitro cytotoxicity against human cells, suggesting that this approach may be useful for the development of compounds more bioactive than the parental species.

Chevalier J.,Aix - Marseille University | Mahamoud A.,Aix - Marseille University | Baitiche M.,Aix - Marseille University | Adam E.,Aix - Marseille University | And 10 more authors.
International Journal of Antimicrobial Agents | Year: 2010

Amongst the three series of quinazoline derivatives synthesised and studied in this work, some molecules increase the antibiotic susceptibility of Gram-negative bacteria presenting multidrug-resistant phenotypes. N-alkyl compounds induced an increase in the activity of chloramphenicol, nalidixic acid and sparfloxacin, which are substrates of the AcrAB-TolC and MexAB-OprM efflux pumps in clinical isolates. These molecules are able to increase the intracellular concentration of chloramphenicol in efflux pump-overproducing strains. Their activity depends on the antibiotic structure, suggesting that different sites may be involved for the recognition of substrates by a given efflux pump. Quinazoline molecules exhibiting a nitro functional group are more active, and structure-activity relationship studies may be undertaken to identify the pharmacophoric group involved in the AcrB and MexB affinity sites. © 2010 Elsevier B.V. and the International Society of Chemotherapy.

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