Photodynamic therapy for methicillin-resistant Staphylococcus aureus infection in a mouse skin abrasion model

Authors

  • Tianhong Dai PhD,

    1. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114
    2. Department of Dermatology, Harvard Medical School, Boston, Massachusetts 02115
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  • George P. Tegos PhD,

    1. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114
    2. Department of Dermatology, Harvard Medical School, Boston, Massachusetts 02115
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  • Timur Zhiyentayev MS,

    1. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114
    2. Chemistry Department, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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  • Eleftherios Mylonakis MD, PhD,

    1. Department of Infectious Disease, Massachusetts General Hospital, Boston, Massachusetts 02114
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  • Michael R. Hamblin PhD

    Corresponding author
    1. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114
    2. Department of Dermatology, Harvard Medical School, Boston, Massachusetts 02115
    3. Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139
    • BAR414, Wellman Center for Photomedicine, Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114.
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Abstract

Background and Objective

Methicillin-resistant Staphylococcus aureus (MRSA) skin infections are now known to be a common and important problem in the Unites States. The objective of this study was to investigate the efficacy of photodynamic therapy (PDT) for the treatment of MRSA infection in skin abrasion wounds using a mouse model.

Study Design/Materials and Methods

A mouse model of skin abrasion wound infected with MRSA was developed. Bioluminescent strain of MRSA, a derivative of ATCC 33591, was used to allow the real-time monitoring of the extent of infection in mouse wounds. PDT was performed with the combination of a polyethylenimine (PEI)–ce6 photosensitizer (PS) and non-coherent red light. In vivo fluorescence imaging was carried out to evaluate the effect of photobleaching of PS during PDT.

Results

In vivo fluorescence imaging of conjugate PEI–ce6 applied in mice indicated the photobleaching effect of the PS during PDT. PDT induced on average 2.7 log10 of inactivation of MRSA as judged by loss of bioluminescence in mouse skin abrasion wounds and accelerated the wound healing on average by 8.6 days in comparison to the untreated infected wounds. Photobleaching of PS in the wound was overcome by adding the PS solution in aliquots.

Conclusion

PDT may represent an alternative approach for the treatment of MRSA skin infections. Lasers Surg. Med. 42:38–44, 2010. © 2010 Wiley-Liss, Inc.

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