Phylogenetic Characteristics of Different Candida Species and Their Impact on the Clinical Picture of Patients With Invasive Candidiasis. What Has Changed During the COVID Pandemic?

Antimicrobial susceptibility testing (AST) of C. parapsilosis strains causing candidemia between 2018 and 2021 has shown a reduced susceptibility to azoles in general, with high rates of fluconazole resistance. This phenotypic profile is most expressed in C. parapsilosis strains; a profile that hasn't been frequently encountered in the past. According to several epidemiological studies, C. parapsilosis strains tend to show echinocandin resistance which drives us to believe that we are facing an outbreak that urges a thorough analysis of the resistances in question.

We have activated a surveillance program to verify whether this episode is of an epidemic nature or rather a sporadic one. Our first concern is that of the emerging fluconazole resistance in C. parapsilosis, which could be attributed to the following phenomena:

• A prolonged treatment with the antifungal in question,
• The well documented point mutation in the ERG11 gene,
• Over-expression of the CDR1 and MDR1 genes which encode for the activity of efflux pumps located on the fungal cell's membrane.

We aimed to:

• Study the incidence of various Candida species causing candidemia to design a local epidemiological framework.
• Determine the most commonly isolated Candida species in BSIs to achieve a better understanding of their phenotypic and genotypic characteristics. This can aid in the choice of an appropriate antifungal treatment with a more accurate prediction of clinical outcomes.
• Studying the potential of different Candida species to produce biofilm which can prove to be highly advantageous, especially in persistent Candida-related infections despite a targeted antifungal treatment.