Effect of antimicrobial photodynamic therapy associated with antifungals against multidrug-resistant Candida auris in vitro and in vivo studies in Galleria mellonella

• Grant number: 23/13826-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: November 01, 2023
• End date: October 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics
• Principal Investigator: Cristina Kurachi
• Grantee: Lívia Mara Alves Figueiredo Godoi
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 13/07276-1 - CEPOF - Optics and Photonic Research Center, AP.CEPID

Abstract

The Candida auris species is considered an emerging pathogen, it was first reported in 2009 in Asia, and has rapidly expanded as an important cause of serious infections around the world. In Brazil, the first C. auris yeasts were identified in December 2020. Unlike other Candida species, C. auris colonizes the skin, has a high transmissibility rate and a high degree of resistance to antifungals. In 2022, the World Health Organization classified this fungal species as a priority for the development of new urgent therapeutic strategies. Antimicrobial photodynamic therapy (aPDT) is currently considered a promising alternative for treating multidrug-resistant (MDR) microorganisms, such as C. auris. The application of this therapy to fungal infections causes damage to the fungal cell membrane, which can increase its permeability and sensitivity to antifungals. Therefore, the present study aims to evaluate the effect of aPDT associated with antifungals on MDR C. auris strains through in vitro and in vivo studies in the G. mellonella experimental model. To this end, clinical strains of MDR C. auris, identified by molecular biology or MALDI-TOF, will be subjected to the minimum inhibitory concentration test for Fluconazole and Caspofungin. The strains will be investigated for their ability to form aggregates. The effects of aPDT mediated by methylene blue and Photodithazine® associated with the use of antifungals will be verified on strains of C. auris MDR, in planktonic culture and biofilms, by the colony forming units counting assay. Next, these effects will be tested in the in vivo model of G. mellonella systemically infected by MDR C. auris strains, using survival curve assays, larval health index and recovery of larval fungal load. The data obtained from tests on planktonic cultures, biofilms, larval health index and recovery of CFU/ g of larvae will be subjected to normality tests, and will be analyzed by ANOVA and Tukey, if considered parametric, or by Kruskal-Wallis and Dunn, if not parametric. For survival curve assays in G. mellonella, the Kaplan-Meier method will be used, with Log-rank (Mantel-Cox). The GraphPad Prism 9.0 program will be used for all statistical analyses, with a significance level of 5%. (AU)