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The effect of light-activated antimicrobial agents on bacterial virulence factors and key modulators of inflammation

Tubby, S.; (2011) The effect of light-activated antimicrobial agents on bacterial virulence factors and key modulators of inflammation. Doctoral thesis, UCL (University College London). Green open access

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Abstract

Photodynamic therapy is a promising new strategy for the treatment of superficial skin infections and periodontitis. A limitation of antibiotic treatment for these diseases is that even after successful killing of the infecting organism, secreted virulence factors may still be present and cause significant damage to host tissues. If light-activated antimicrobial agents can inactivate microbial virulence factors in addition to killing the pathogenic microorganisms, this would represent an advantage of photodynamic therapy over conventional treatment options. The light-activated antimicrobial agents methylene blue and tin chlorin e6 in combination with laser light of 665 and 633 nm respectively, were assessed for their antibacterial activity and ability to reduce the activity of selected virulence factors of Staphylococcus aureus and Porphyromonas gingivalis. In addition to successfully reducing the microbial burden, it was demonstrated that photosensitisation was able to cause significant reductions in the activity of a number of secreted and cell wall-associated virulence factors produced by these species when irradiated with laser light of the appropriate wavelength. Photosensitisation was also shown to reduce the biological activities of the proinflammatory cytokines tumour necrosis factor-alpha and interleukin-6, which are produced in response to infecting bacteria and are associated with damage to host tissues. The results of these studies indicate that light-activated antimicrobial agents may be useful in reducing the pathology associated with bacterial virulence factors and host-mediated inflammation when used as part of an antimicrobial treatment regimen.

Type:Thesis (Doctoral)
Title:The effect of light-activated antimicrobial agents on bacterial virulence factors and key modulators of inflammation
Open access status:An open access version is available from UCL Discovery
Language:English
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Microbial Diseases

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