As a chronic cutaneous and subcutaneous infection, thousands of cases of chromoblastomycosis (CBM) have been reported worldwide. During the past centuries, several therapeutic regimens have been proposed including systemic antifungals, as monotherapy or combined, physical methods and immune adjuvants. Antifungal Photodynamic Therapy (APDT) has been successfully employed in combination with or without antifungals recently.  
Objectives: To evaluate the photodynamic inactivation of different photosensitizers against Fonsecaea monophora in vitro and investigate their mechanisms. And to review available data regarding the APDT for CBM, discuss their application, advantages and shortages in clinic. 
Methods: The photodynamic inactivation efficacy of three photosensitizers, Methylene blue (MB), 5,10,15,20-tetra-(N-methyl-4-pyridyl) porphyrin (TMPyP4), 5-Aminolaevulinic Acid (5-ALA) against F. monophora were compared. The reactive oxygen species (ROS) species involved in their cytotoxicity were investigated with 5-(and-6)-chloromethyl-2-,7-di- chlorofluorescin diacetate (DCFH-DA) probe. The effect of 5-ALA-PDI treated F. monophora conidia on macrophage was also tested. Moreover, clinical APDT treated CBM cases were reviewed and analyzed.
Results: In the in vitro investigation, it was observed that all of the three photosensitizers can inactivate F. monophora conidia directly with corresponding-wavelength light illumination in a concentration-dependent and dose-dependent manner. TMPyP4 had the best inactivation effect compared to other two photosensitizers, giving 5 log10 steps killing at concentrations of 50μM with 10J/cm2 blue light, while 5-ALA needed around 80μM with 90J/cm2 red light. The green fluorescence of DCFH-DA probe showed that ALA-PDT increase intracellular ROS levels in F. monophora concentration-dependently and light dose-independently. Furthermore, macrophage cell RAW264.7 was activated indirectly by photodynamical treated conidia. ALA-PDT can enhance the fungicidal ability of RAW264.7 and protect it from Infection-induced apoptosis in an indirect way. ROS generated by photodynamic treated conidia is associated with mitochondrial-related apoptosis in RAW264.7. APDT has the advantages of equal killing effectiveness regardless of antibiotic resistance. However, the antimicrobial effect will be ceased when the light is turned off and some side effects will occur with longtime application, such as pain. Several PDT sessions which is well-tolerated can result in improvement and even complete remission of lesions.
Conclusion: Although most of the advanced CBM forms require long-term continuous systemic antifungal therapy, the variable modalities of physical methods are available as an adjuvant therapy. APDT could be used as promising physical approaches to decrease disease severity and duration while enhancing the quality of life of the patients. The use of different photosensitizers shows different antifungal efficacy. It is significant to choose a suitable photosensitizer for a specific pathogen. Yet the mechanism is still not clear which merits further investigation.

4 / In vitro study of photodynamic inactivation against Fonsecaea monophora and the application of ALA-APDT on refractory Chromoblastomycosis