title: Pseudomonas aeruginosa Biofilm Response and Resistance to Cold Atmospheric Pressure Plasma Is Linked to the Redox-Active Molecule Phenazine.
abstract: Pseudomonas aeruginosa is an important opportunistic pathogen displaying high antibiotic resistance. Its resistance is in part due to its outstanding ability to form biofilms on a range of biotic and abiotic surfaces leading to difficult-to-treat, often long-term infections. Cold atmospheric plasma (CAP) is a new, promising antibacterial treatment to combat antibiotic-resistant bacteria. Plasma is ionized gas that has antibacterial properties through the generation of a mix of reactive oxygen and nitrogen species (RONS), excited molecules, charged particles and UV photons. Our results show the efficient removal of P. aeruginosa biofilms using a plasma jet (kINPen med), with no viable cells detected after 5 min treatment and no attached biofilm cells visible with confocal microscopy after 10 min plasma treatment. Because of its multi-factorial action, it is widely presumed that the development of bacterial resistance to plasma is unlikely. However, our results indicate that a short plasma treatment (3 min) may lead to the emergence of a small number of surviving cells exhibiting enhanced resistance to subsequent plasma exposure. Interestingly, these cells also exhibited a higher degree of resistance to hydrogen peroxide. Whole genome comparison between surviving cells and control cells revealed 10 distinct polymorphic regions, including four belonging to the redox active, antibiotic pigment phenazine. Subsequently, the interaction between phenazine production and CAP resistance was demonstrated in biofilms of transposon mutants disrupted in different phenazine pathway genes which exhibited significantly altered sensitivity to CAP.
authors.affiliation: CSIRO Manufacturing Flagship, P.O. Box 218, Lindfield, NSW 2070, Australia.
authors.forename: Anne
authors.initials: A
authors.lastname: Mai-Prochnow
authors.affiliation: CSIRO Food and Nutrition Flagship, 11 Julius Ave, North Ryde, NSW 2113, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Bradbury
authors.affiliation: CSIRO Manufacturing Flagship, P.O. Box 218, Lindfield, NSW 2070, Australia; Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Earth Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia.
authors.forename: Kostya
authors.initials: K
authors.lastname: Ostrikov
authors.affiliation: CSIRO Manufacturing Flagship, P.O. Box 218, Lindfield, NSW 2070, Australia.
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Murphy
mesh_terms: D018441:Biofilms / Q000187:drug effects*; D016680:Genome, Bacterial / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects; D010084:Oxidation-Reduction; D010619:Phenazines / Q000494:pharmacology*; D058626:Plasma Gases / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000502:physiology*
chemical_list: D010619:Phenazines; D058626:Plasma Gases; C000598831:phenazine; D006861:Hydrogen Peroxide