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Proceedings Paper

Photodynamic inactivation of Staphylococcus aureus and Escherichia coli using a new bacteriochlorin as photosensitizer
Author(s): Diego D. Barboza; Laura C. A. Martins; Thaila Quatrini Corrêa; Mariana Carreira Geralde; Sebastião Pratavieira; Kleber Thiago de Oliveira; Marciana P. Uliana; Clovis W. de Souza
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Paper Abstract

In this study, we used bacteriochlorin as a photosensitizer, characterized by their low toxicity in the absence of light, presenting absorption around 780 nm, with the objective of evaluating their photodynamic inactivation potential on Staphylococcus aureus and Escherichia coli. Bacteriochlorins were synthesized from the extraction of bacteriochlorophylls from non-sulfurous purple bacteria and were then converted to bacteriochlorins. S. aureus and E. coli microorganisms were used in the planktonic and biofilm forms. For the formation of biofilms on glass coverslips, suspensions of the microorganisms at the concentration of 106 CFU/mL were inoculated into each well of a microplate. There was an exchange of culture medium (Tryptic Soy Broth - TSB) every 24 hours for 7 days, pre-washing the coverslips with a phosphate-buffered saline (PBS), to ensure that only adhered microorganisms were grown and then incubated at (36 ± 1)°C between the middle exchanges. After 7 days of induction, the biofilm was mature, like those normally found in nature, and then it was applied different treatments (light doses associated with FS concentrations). At the end of the treatment, the coverslips underwent an ultrasonic disintegration, and the quantitative evaluation of viable cells was performed by plate counting using the plate method in Tryptic Soy Agar (TSA), incubating at (36 ± 1)°C for 24 hours. The results showed that the PDI for E. coli was not successful even when it was more susceptible to the planktonic form, whereas for S. aureus the results showed a reduction in cell viability 6 logs for the planktonic forms, but lower to 1 log in biofilms. Therefore, novel studies using bacteriochlorins and surfactants will be performed to verify the potential of this alternative treatment method.

Paper Details

Date Published: 12 February 2018
PDF: 9 pages
Proc. SPIE 10476, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII, 104760X (12 February 2018);
Show Author Affiliations
Diego D. Barboza, Federal Univ. of São Carlos (Brazil)
Laura C. A. Martins, Federal Univ. of São Carlos (Brazil)
Thaila Quatrini Corrêa, Univ. de São Paulo (Brazil)
Mariana Carreira Geralde, Univ. de São Paulo (Brazil)
Sebastião Pratavieira, Univ. de São Paulo (Brazil)
Kleber Thiago de Oliveira, Federal Univ. of São Carlos (Brazil)
Marciana P. Uliana, Federal Univ. for Latin American Integration (Brazil)
Clovis W. de Souza, Federal Univ. of São Carlos (Brazil)

Published in SPIE Proceedings Vol. 10476:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII
David H. Kessel; Tayyaba Hasan, Editor(s)

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