Influence of bacterial interactions on the susceptibility to photodynamic inactivation

M. H. Upadya; G. Tegos; M. Hamblin; A. Kishen

doi:10.1117/12.822851

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13 July 2009 Influence of bacterial interactions on the susceptibility to photodynamic inactivation

M. H. Upadya, G. Tegos, M. Hamblin, A. Kishen

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Proceedings Volume 7380, Photodynamic Therapy: Back to the Future; 73803D (2009) https://doi.org/10.1117/12.822851
Event: 12th World Congress of the International Photodynamic Association, 2009, Seattle, Washington, United States

Abstract

Photodynamic therapy has emerged as a possible supplement to the existing protocols for endodontic disinfection. Microbes are known to gain significant ecological advantage when they survive as coaggregates and biofilms in an infected tissue. Such microbial coaggregates and biofilms have been confirmed to play a key role in the pathogenicity of many infections. So far, not many studies have correlated the efficacy of antimicrobial photodynamic inactivation (APDI) to the different modes of bacterial growth. This study aims to evaluate the APDI of 3 strains of Enterococcus faecalis in planktonic phase, in a co-aggregated suspension and in a 4-day old biofilm. The results showed that the biofilm mode of growth offered the greatest resistance to APDI and the inclusion of an efflux pump inhibitor significantly increased the APDI of biofilm bacteria. From this study, we conclude that APDI of bacteria in biofilms is the most challenging and that the use of bacterial efflux pump inhibitors enhances its photodynamic antibiofilm efficacy.

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M. H. Upadya, G. Tegos, M. Hamblin, and A. Kishen "Influence of bacterial interactions on the susceptibility to photodynamic inactivation", Proc. SPIE 7380, Photodynamic Therapy: Back to the Future, 73803D (13 July 2009); https://doi.org/10.1117/12.822851

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