title: Advances toward the elucidation of hypertonic saline effects on Pseudomonas aeruginosa from cystic fibrosis patients.
abstract: OBJECTIVE
  Nebulized hypertonic saline (HTS) has beneficial effects including reducing pulmonary exacerbations in Cystic Fibrosis (CF) patients. Several mechanisms may explain these effects but antimicrobial activity of NaCl remains largely unexplored. We aimed to measure the antimicrobial effect of NaCl on Pseudomonas aeruginosa isolated from the respiratory tract in CF patients.
  
  
  METHODS
  NaCl minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined for strains characterized for mucoidy, antimicrobial resistance, and ability to form biofilm using 0,9% to 15% NaCl solutions. NaCl effects on biofilm formation, preformed biofilm, and mobility were evaluated. Kinetics of antimicrobial effects was studied.
  
  
  RESULTS
  The growth of all isolates (n = 85) from 34 patients was inhibited by 6% NaCl solution. A 10% concentration had a bactericidal activity on 90% of the isolates. Mucoid and multidrug resistant (MDR) isolates displayed lower MICs compared to non-mucoid and to non-MDR isolates, respectively. Time-kill kinetics showed that NaCl exhibited a rapid, dose and growth phase dependent bactericidal effect. Three percent or more of NaCl inhibited biofilm formation for 69% of strongly adherent isolates. A dose-dependent decrease of preformed biofilm viability and an inhibitory activity on bacterial motility were observed.
  
  
  CONCLUSIONS
  NaCl inhibited the growth of all isolates and killed 38% of tested isolates within concentration range currently used in therapeutics. Our results suggest that anti-pseudomonal activity is another mechanism of action of HTS to add to those already established. Clinical trials are needed to compare diverse HTS conditions of use (rhythm, dose and mode of delivery) to obtain efficient and optimized anti-P. aeruginosa effects. More generally, NaCl effect on other opportunistic pathogens as well as on global microbiotae recovered during polymicrobial diseases warrants further investigations.
authors.affiliation: UMR 5119 ECOSYM, Equipe Pathogènes et Environnements, U.F.R. des Sciences Pharmaceutiques et Biologiques, Université Montpellier 1, Montpellier, France ; Laboratoire de Bactériologie, Hôpital Arnaud de Villeneuve, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Michon
authors.affiliation: UMR 5119 ECOSYM, Equipe Pathogènes et Environnements, U.F.R. des Sciences Pharmaceutiques et Biologiques, Université Montpellier 1, Montpellier, France ; Laboratoire d'Hygiène hospitalière, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France.
authors.forename: Estelle
authors.initials: E
authors.lastname: Jumas-Bilak
authors.affiliation: Centre de Ressources et de Compétences pour la Mucoviscidose, Hôpital Arnaud de Villeneuve, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Chiron
authors.affiliation: UMR 5119 ECOSYM, Equipe Pathogènes et Environnements, U.F.R. des Sciences Pharmaceutiques et Biologiques, Université Montpellier 1, Montpellier, France ; Laboratoire de Bactériologie, Hôpital Arnaud de Villeneuve, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Lamy
authors.affiliation: UMR 5119 ECOSYM, Equipe Pathogènes et Environnements, U.F.R. des Sciences Pharmaceutiques et Biologiques, Université Montpellier 1, Montpellier, France ; Laboratoire de Bactériologie, Hôpital Arnaud de Villeneuve, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Marchandin
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D003550:Cystic Fibrosis / Q000150:complications / Q000382:microbiology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000150:complications / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D012462:Saline Solution, Hypertonic