title: Nitrite modulates bacterial antibiotic susceptibility and biofilm formation in association with airway epithelial cells.
abstract: Pseudomonas aeruginosa is the major pathogenic bacteria in cystic fibrosis and other forms of bronchiectasis. Growth in antibiotic-resistant biofilms contributes to the virulence of this organism. Sodium nitrite has antimicrobial properties and has been tolerated as a nebulized compound at high concentrations in human subjects with pulmonary hypertension; however, its effects have not been evaluated on biotic biofilms or in combination with other clinically useful antibiotics. We grew P. aeruginosa on the apical surface of primary human airway epithelial cells to test the efficacy of sodium nitrite against biotic biofilms. Nitrite alone prevented 99% of biofilm growth. We then identified significant cooperative interactions between nitrite and polymyxins. For P. aeruginosa growing on primary CF airway cells, combining nitrite and colistimethate resulted in an additional log of bacterial inhibition compared to treating with either agent alone. Nitrite and colistimethate additively inhibited oxygen consumption by P. aeruginosa. Surprisingly, whereas the antimicrobial effects of nitrite in planktonic, aerated cultures are nitric oxide (NO) dependent, antimicrobial effects under other growth conditions are not. The inhibitory effect of nitrite on bacterial oxygen consumption and biofilm growth did not require NO as an intermediate as chemically scavenging NO did not block growth inhibition. These data suggest an NO-radical independent nitrosative or oxidative inhibition of respiration. The combination of nebulized sodium nitrite and colistimethate may provide a novel therapy for chronic P. aeruginosa airway infections, because sodium nitrite, unlike other antibiotic respiratory chain "poisons," can be safely nebulized at high concentration in humans.
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Zemke
authors.affiliation: Department of Pharmacology, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Sruti
authors.initials: S
authors.lastname: Shiva
authors.affiliation: Department of Pediatrics, University of Washington, Seattle, WA 98195, USA.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Burns
authors.affiliation: Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Moskowitz
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Pilewski
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA; Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, Pittsburgh, PA 15219, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Gladwin
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA 15219, USA. Electronic address: jbomb@pitt.edu.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Bomberger
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms; D001980:Bronchi / Q000166:cytology; D002478:Cells, Cultured; D003091:Colistin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004847:Epithelial Cells / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009569:Nitric Oxide / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology*; D012977:Sodium Nitrite / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D009569:Nitric Oxide; D012977:Sodium Nitrite; D010100:Oxygen; D003091:Colistin
keywords: Biofilm; Colistimethate; Colistin; Polymyxin; Pseudomonas aeruginosa; Sodium nitrite