title: Blue light treatment of Pseudomonas aeruginosa: Strong bactericidal activity, synergism with antibiotics and inactivation of virulence factors.
abstract: Pseudomonas aeruginosa is among the most common pathogens responsible for both acute and chronic infections of high incidence and severity. Additionally, P. aeruginosa resistance to conventional antimicrobials has increased rapidly over the past decade. Therefore, it is crucial to explore new therapeutic options, particularly options that specifically target the pathogenic mechanisms of this microbe. The ability of a pathogenic bacterium to cause disease is dependent upon the production of agents termed 'virulence factors', and approaches to mitigate these agents have gained increasing attention as new antibacterial strategies. Although blue light irradiation is a promising alternative approach, only limited and preliminary studies have described its effect on virulence factors. The current study aimed to investigate the effects of lethal and sub-lethal doses of blue light treatment (BLT) on P. aeruginosa virulence factors. We analyzed the inhibitory effects of blue light irradiation on the production/activity of several virulence factors. Lethal BLT inhibited the activity of pyocyanin, staphylolysin, pseudolysin and other proteases, but sub-lethal BLT did not affect the production/expression of proteases, phospholipases, and flagella- or type IV pili-associated motility. Moreover, a eukaryotic cytotoxicity test confirmed the decreased toxicity of blue light-treated extracellular P. aeruginosa fractions. Finally, the increased antimicrobial susceptibility of P. aeruginosa treated with sequential doses of sub-lethal BLT was demonstrated with a checkerboard test. Thus, this work provides evidence-based proof of the susceptibility of drug-resistant P. aeruginosa to BLT-mediated killing, accompanied by virulence factor reduction, and describes the synergy between antibiotics and sub-lethal BLT.
authors.affiliation: a Laboratory of Molecular Diagnostics, Department of Biotechnology , Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk , Gdansk , Poland.
authors.forename: Grzegorz
authors.identifier: 0000-0003-0953-0959
authors.initials: G
authors.lastname: Fila
authors.affiliation: b Division of Plant Protection and Biotechnology, Department of Biotechnology , Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk , Gdansk , Poland.|c Laboratory of Human Physiology , Medical University of Gdansk , Gdansk , Poland.
authors.forename: Anna
authors.identifier: 0000-0001-8105-2555
authors.initials: A
authors.lastname: Kawiak
authors.affiliation: a Laboratory of Molecular Diagnostics, Department of Biotechnology , Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk , Gdansk , Poland.
authors.forename: Mariusz Stanislaw
authors.identifier: 0000-0003-4041-0891
authors.initials: MS
authors.lastname: Grinholc
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000528:radiation effects; D003116:Color; D006801:Humans; D008027:Light; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000528:radiation effects; D008826:Microbial Sensitivity Tests; D010196:Pancreatic Elastase / Q000528:radiation effects; D011552:Pseudomonas Infections / Q000382:microbiology / Q000628:therapy; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000528:radiation effects*; D014774:Virulence / Q000528:radiation effects; D037521:Virulence Factors / Q000037:antagonists & inhibitors / Q000528:radiation effects*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D037521:Virulence Factors; D010196:Pancreatic Elastase; D008666:Metalloendopeptidases; C043859:pseudolysin, Pseudomonas aeruginosa
keywords: Pseudomonas aeruginosa; blue light treatment; elastases; hemolysins; lipases; motility; photoinactivation; proteases; virulence factors