title: Anaerobic killing of mucoid Pseudomonas aeruginosa by acidified nitrite derivatives under cystic fibrosis airway conditions.
abstract: Mucoid, mucA mutant Pseudomonas aeruginosa cause chronic lung infections in cystic fibrosis (CF) patients and are refractory to phagocytosis and antibiotics. Here we show that mucoid bacteria perish during anaerobic exposure to 15 mM nitrite (NO2) at pH 6.5, which mimics CF airway mucus. Killing required a pH lower than 7, implicating formation of nitrous acid (HNO2) and NO, that adds NO equivalents to cellular molecules. Eighty-seven percent of CF isolates possessed mucA mutations and were killed by HNO2 (3-log reduction in 4 days). Furthermore, antibiotic-resistant strains determined were also equally sensitive to HNO2. More importantly, HNO2 killed mucoid bacteria (a) in anaerobic biofilms; (b) in vitro in ultrasupernatants of airway secretions derived from explanted CF patient lungs; and (c) in mouse lungs in vivo in a pH-dependent fashion, with no organisms remaining after daily exposure to HNO2 for 16 days. HNO2 at these levels of acidity and NO2 also had no adverse effects on cultured human airway epithelia in vitro. In summary, selective killing by HNO2 may provide novel insights into the important clinical goal of eradicating mucoid P. aeruginosa from the CF airways.
authors.affiliation: Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0524, USA.
authors.forename: Sang Sun
authors.initials: SS
authors.lastname: Yoon
authors.forename: Ray
authors.initials: R
authors.lastname: Coakley
authors.forename: Gee W
authors.initials: GW
authors.lastname: Lau
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Lymar
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gaston
authors.forename: Ahmet C
authors.initials: AC
authors.lastname: Karabulut
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hennigan
authors.forename: Sung-Hei
authors.initials: SH
authors.lastname: Hwang
authors.forename: Garry
authors.initials: G
authors.lastname: Buettner
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Schurr
authors.forename: Joel E
authors.initials: JE
authors.lastname: Mortensen
authors.forename: Jane L
authors.initials: JL
authors.lastname: Burns
authors.forename: David
authors.initials: D
authors.lastname: Speert
authors.forename: Richard C
authors.initials: RC
authors.lastname: Boucher
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hassett
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004847:Epithelial Cells / Q000166:cytology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D051379:Mice; D008826:Microbial Sensitivity Tests; D009093:Mucus / Q000737:chemistry; D009573:Nitrites / Q000378:metabolism*; D011552:Pseudomonas Infections; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000166:cytology; D013183:Sputum / Q000737:chemistry / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; C107895:MucA protein, Pseudomonas; D009573:Nitrites