Pseudomonas aeruginosa is an opportunistic pathogen resistant to many antibiotics, able to form biofilm and causes serious nosocomial infections. Among anti-Pseudomonas light-based approaches, the recent antimicrobial Blue Light (aBL) treatment seems very promising. The aim of this study was to evaluate the efficiency of blue light in inhibiting and/or eradicating P. aeruginosa biofilm. Light at 410 nm has been identified as successful in inhibiting biofilm formation not only of the model strain PAO1, but also of CAUTI (catheter-associated urinary tract infection) isolates characterized by their ability to form biofilm. Results of this work on 410 nm light also demonstrated that: i) at the lowest tested radiant exposure (75 J cm-2) prevents matrix formation; ii) higher radiant exposures (225 and 450 J cm-2) light impairs the cellular components of biofilm, adherent and planktonic ones; iii) light eradicates with a good rate young and older biofilms in a light dose dependent manner; iv) it is also efficient in inactivating catalase A, a virulence factor playing an important role in pathogenic mechanisms. Light at 455 nm, even if at a lower extent than 410 nm, showed a certain anti-Pseudomonas activity. Furthermore, light at 410 nm caused detrimental effects on enzyme activity of β-galactosidase and catalase A, and changes on plasmid DNA conformation and ortho-nitrophenyl-β-D-galactopyranoside structure. This study supports the potential of blue light for anti-infective and disinfection applications.
Keywords: Antimicrobial blue light; Phototherapy; Pseudomonas aeruginosa, blue light, biofilm.
Copyright © 2020 Elsevier B.V. All rights reserved.