Cryptococcus gattii: in vitro susceptibility to photodynamic inactivation.
Cryptococus gattii is an emergent primary human pathogen that causes meningismus, papilledema, high intracranial pressure and focal involvement of the central nervous system in immunocompetent hosts. Prolonged antifungal therapy is the conventional treatment, but it is highly toxic, selects for resistant strains, contributes to therapy failure and has a poor prognosis. Photodynamic inactivation (PDI) offers a promising possibility for the alternative treatment of cryptococcosis. The aim of this study was to test the effectiveness of toluidine blue O (TBO) and light-emitting diode (LED) against C. gattii strains with distinct susceptibility profile to antifungal drugs (amphotericin B: 0.015-1.0 μg mL(-1); itraconazole: 0.015-2 μg mL(-1); fluconazole: 4-64 μg mL(-1)). Using 25 μM (6.76 μg mL(-1)) TBO and LED energy density of 54 J cm(-2) these fungal isolates presented variable susceptibility to PDI. The production of reactive oxygen species (ROS)/peroxynitrite was determined, and the catalase and peroxidase activities were measured. After PDI, high amounts of ROS/peroxynitrite are produced and higher catalase and peroxidase activities could be correlated with a lower susceptibility of C. gattii isolates to PDI. These results indicate that PDI could be an alternative to C. gattii growth inhibition, even of isolates less susceptible to classical antifungal drugs, also pointing to mechanisms related to their variable susceptibility behavior.
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. bmsoares@gmail.com
Betânia Maria
BM
Soares
Orley Araújo
OA
Alves
Marcus Vinícius Lucas
MV
Ferreira
José Cláudio Faria
JC
Amorim
Gerdal Roberto
GR
Sousa
Lívio de Barros
Lde B
Silveira
Renato Araújo
RA
Prates
Thiago Vinícius
TV
Avila
Ludmila de Matos
Lde M
Baltazar
Daniele da Glória
Dda G
de Souza
Daniel Assis
DA
Santos
Luzia Valentina
LV
Modolo
Patrícia Silva
PS
Cisalpino
Marcos
M
Pinotti
D000935:Antifungal Agents / Q000627:therapeutic use; D003453:Cryptococcosis / Q000532:radiotherapy; D056285:Cryptococcus gattii / Q000528:radiation effects*; D006801:Humans; D010778:Photochemotherapy; D010787:Photosensitivity Disorders; D014048:Tolonium Chloride / Q000627:therapeutic use
D000935:Antifungal Agents; D014048:Tolonium Chloride