title: Discovering the mechanisms of strain-dependent response of Staphylococcus aureus to photoinactivation: oxidative stress toleration, endogenous porphyrin level and strain's virulence.
abstract: BACKGROUND
  Staphylococcus aureus is generally known to be susceptible to photoinactivation. However, the phenomenon of its strain-dependent response to photodynamic treatment has been reported. Moreover, the factors determining the emerging variation among strains according to photoinactivation remain unclear.
  
  
  METHODS
  This work aimed to investigate any relevant correlation between bacterial toleration of oxidative stress, porphyrin level, photosensitizer uptake and strain's virulence of studied methicillin-susceptible and methicillin-resistant S. aureus strains and their response to photodynamic inactivation (using protoporphyrin diarginate, toluidine blue O and 5-aminolevulinic acid).
  
  
  RESULTS
  Obtained data let to demonstrate that studied factors have limited impact on strain response to PDI. However, we have shown that multicomponent sensitizing agent i.e. consisted of PPArg2, ALA and TBO would eliminate the S. aureus elevated resistance to photoinactivation and that both highly virulent and low virulent S. aureus strains could be easily eradicated with the use of PDI. Moreover, we have shown that photodynamic inactivation could decrease the virulence of S. aureus extracellular fraction.
  
  
  CONCLUSIONS
  The mechanism underlying strain-dependent response to photoinactivation is complex and multifactorial nevertheless with the use of several sensitizing agents the elevated resistance to photodynamic treatment can be omitted.
authors.affiliation: Laboratory of Molecular Diagnostics, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Kladki 24, 80-822 Gdansk, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Kossakowska
authors.forename: Joanna
authors.initials: J
authors.lastname: Nakonieczna
authors.forename: Anna
authors.initials: A
authors.lastname: Kawiak
authors.forename: Julianna
authors.initials: J
authors.lastname: Kurlenda
authors.forename: Krzysztof P
authors.initials: KP
authors.lastname: Bielawski
authors.forename: Mariusz
authors.initials: M
authors.lastname: Grinholc
mesh_terms: D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival; D006801:Humans; D015603:Keratinocytes / Q000382:microbiology* / Q000502:physiology; D008027:Light; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011166:Porphyrins / Q000378:metabolism*; D011836:Radiation Tolerance / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D013045:Species Specificity; D013211:Staphylococcus aureus / Q000145:classification* / Q000502:physiology* / Q000528:radiation effects; D014774:Virulence / Q000502:physiology
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins
keywords: Endogenous porphyrins; Oxidative stress; Photoinactivation; Porphyrins; S. aureus virulence; Toluidine blue O