Potential of a antimicrobial photodynamic therapy in the development of resistance in Candida albicans

Author(s)

Luana Mendonça Dias Santana

• Document type: Master's Dissertation
• Press: Araraquara. 2020-05-26.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2020-04-09
• Advisor: Ana Claudia Pavarina

Abstract

The fungus Candida albicans, in situations of immune imbalance in the host, can become an opportunistic pathogen and cause infections. Because of the resistance that microorganisms have developed to conventional drugs, Antimicrobial Photodynamic Therapy (aPDT) has shown promising results as an alternative therapy. The main goal of this study was to evaluate the potential of aPDT to develop resistance in C. albicans in association with Photodithazine (PDZ-25 µg/L; 660 nm; 18 J/cm2) and Curcumin (CUR-40 µg/L; 455 nm; 18 J/cm2) grown with and without Fluconazole (8 µg/L). C. albicans (ATCC 90028), in planktonic and biofilm cultures, were submitted to successive applications of aPDT (10 applications), as well as cycles of recovery and re-cultivation of colonies that survived treatment until no longer viable cells were present for application recovery and continuation. Plating was performed on Sabourand Dextrose Agar plates supplemented or not with Fluconazole, and values of colony forming units per milliliter (CFU/mL) were determined. The reactive oxygen species (ROS) production test was performed in the first and last cycles of aPDT. The biomolecular profile of surviving cells as applications 1, 4 and 7 of PDZ-mediated aPDT was investigated using the RT-qPCR test. PDZ-mediated treatment of aPDT (P+L+) was observed to reduce approximately 6.8 log10 in planktonic cultures and approximately 6.2 log10 in C. albicans biofilm in both methodologies used. In the aPDT (C+L+) treatment group in combination with the CUR, viability was increased by approximately 1 log10 in C. abicans biofilms. In the control group of the experiment (PL-), in the successive applications methodology, no statistical difference was observed between the applications (p> 0.05). The results showed lower viability of C. albicans planktonic cultures and biofilms grown on fluconazole plates when compared to plates without antifungal. The latest successive applications of aPDT produced more ROS compared to the first application. aPDT overexpressed the SOD1 gene and reduced expression of the CAP1 and ERG11 gene. The type of culture influences susceptibility to aPDT, since different amounts of applications were necessary for its inactivation. The type of culture influences susceptibility to aPDT, since different amounts of applications were necessary for its inactivation. The aPDT was potentiated by the fluconazole antifungal, independent of the model and photosensitizer tested. C. albicans (ATCC 90028) in planktonic culture and biofilm is susceptible to repeated applications of PDZ-mediated aPDT, however, when CUR-mediated, biofilms showed increased viability after cycles. (AU)

• FAPESP's process: 18/14874-6 - Potential of antimicrobial photodynamic therapy in the development of resistance in Candida albicans
• Grantee: Luana Mendonça Dias Santana
• Support Opportunities: Scholarships in Brazil - Master