title: [Time-kill curves and evolution of membrane permeability after para-guanidinoethylcalix[4]arene exposure].
abstract: Three problems at the moment: multidrug-resistant bacteria, healthcare-associated infections, and decrease of active antibiotics. We have an urgent need of new antibacterials, with an innovative mechanism of action, in order to avoid too quickly bacterial resistance. The first interface between bacteria and antibiotics is the bacterial cell wall. It is a very interesting target, as far as some components or motives are highly conserved between genus or species, and wall destabilization conduct rapidly to bacterial lysis. However, few methods are at our disposal to study rapidly impact of such antibacterials on the structure, composition or functions of the bacterial cell wall. The paraguanidinoethylcalix[4]arene (Cx1) is a new cationic antibacterial drug, with a broad spectrum, not toxic, active on multidrug-resistant bacteria, with a possible parietal target, but with unknown kind of activity (i.e. bactericidal or bacteriostatic). We thus developed, at the same time as the realization of the time-kill curves, a technique to stain bacteria with two dyes: SYTO9 and propidium iodide (PI), to follow the membrane permeability modifications, due to Cx1 exposure. The obtained results demonstrate, for Escherichia coli ATCC 25922, that Cx1 possesses a bactericidal activity, concentration-dependent, with a gradual achievement of membrane permeability, time- and concentration-dependent, with the presence of filamentous bacteria.
  
  
  CONCLUSIONS
  the SYTO9-PI double staining, allows a simple and fast detection, easy to implement, of the impact of new antibacterial on the bacterial wall; and Cx1 interacts well with the bacterial wall, pulling in the end a loss of membrane integrity.
authors.affiliation: SRSMC, CNRS, Nancy-Université, France. marion.grare.1@etumail.uhp-nancy.fr
authors.forename: M
authors.initials: M
authors.lastname: Grare
authors.forename: S
authors.initials: S
authors.lastname: Fontanay
authors.forename: H
authors.initials: H
authors.lastname: Massimba Dibama
authors.forename: M
authors.initials: M
authors.lastname: Mourer
authors.forename: J-B
authors.initials: JB
authors.lastname: Regnouf-de-Vains
authors.forename: C
authors.initials: C
authors.lastname: Finance
authors.forename: R E
authors.initials: RE
authors.lastname: Duval
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D047250:Calixarenes / Q000737:chemistry / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002473:Cell Wall / Q000187:drug effects* / Q000378:metabolism; D004396:Coloring Agents; D004305:Dose-Response Relationship, Drug; D055808:Drug Discovery; D004353:Drug Evaluation, Preclinical; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests / Q000706:statistics & numerical data*; D008856:Microscopy, Fluorescence; D015394:Molecular Structure; D009930:Organic Chemicals; D011419:Propidium; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D004396:Coloring Agents; D009930:Organic Chemicals; C103389:SYTO 9; C524784:para-guanidinoethylcalix(4)arene; D047250:Calixarenes; D011419:Propidium