Merocyanine-540 mediated photodynamic effects on Staphylococcus epidermidis biofilms

Maria Sonia Sbarra, Antonella Di Poto, Enrica Saino, Livia Visai, Paolo Minzioni, Francesca Bragheri, Ilaria Cristiani

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Staphylococci are important causes of nosocomial and medical-device-related infections. Their virulence is attributed to the elaboration of biofilms that protect the organisms from immune system clearance and to increased resistance to phagocytosis and antibiotics. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria in biofilms. In this study, we evaluated the antimicrobial activity of merocyanine 540 (MC 540), a photosensitizing dye that is used for purging malignant cells from autologous bone marrow grafts, against Staphylococcus epidermidis biofilms. We evaluated the effect of the combined photodynamic action of MC 540 and 532 nm laser on the viability and structure of biofilms of two Staphylococcus epidermidis strains. Significant inactivation of cells was observed in the biofilms treated with MC-540 and then exposed to laser radiation. Furthermore we found that the PDT effect, on both types of cells, was significantly dependent on both the light-dose and on the impinging lightintensity. Disruption of PDT-treated biofilm was confirmed by scanning electron microscopy (SEM).

Original languageEnglish
Title of host publicationOptics InfoBase Conference Papers
PublisherOptical Society of America
ISBN (Print)9780819476432
Publication statusPublished - 2009
EventEuropean Conference on Biomedical Optics, ECBO 2009 - Munich, Germany
Duration: Jun 14 2009Jun 18 2009


OtherEuropean Conference on Biomedical Optics, ECBO 2009


  • Merocyanine 540 (MC 540)
  • Photodynamic therapy (PDT)
  • S. epidermidis biofilms

ASJC Scopus subject areas

  • Instrumentation
  • Atomic and Molecular Physics, and Optics


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