Microsatellite Genotyping of Clinical and Environmental <i>Aspergillus flavus</i>

Abstract

Background: Aspergillus flavus is one of the primary causes of human aspergillosis. Several molecular methods have been developed to genotype Aspergillus species. Microsatellite length polymorphism (MLP) analysis enables discrimination between fungal strains and assessment of their genetic diversity. Fungal biofilms are resilient communities that protect against antifungals and immune responses. The limited genotypic data on A. flavus populations highlights the novelty of this study, which utilizes microsatellite markers to clarify the genetic diversity and population structure of clinical and environmental isolates. Objectives: In this study, we determined the genotypic pattern, antifungal susceptibility profiles, and biofilm formation in clinical and environmental A. flavus. Methods: DNA from 50 A. flavus isolates was used for molecular identification using the calmodulin gene. Isolates were genotyped using six microsatellite markers specific to A. flavus, employing the MLP technique. Antifungal susceptibility profiles were determined against eight antifungal agents following Clinical and Laboratory Standards Institute (CLSI) M38 3rd edition guidelines. Biofilm formation ability was assessed for all isolates. Results: Forty-nine different genotypes were detected with the six polymorphic loci among the 50 A. flavus isolates. Genotypic analysis revealed a high degree of genetic diversity, although two environmental isolates were found to be genotypically identical. The combined discriminatory power for all six markers was 0.9777. All isolates were wild-type for caspofungin and voriconazole. Only one environmental isolate showed resistance to amphotericin B. Luliconazole had the lowest geometric mean (GM) minimum inhibitory concentrations (0.0126 μg/mL). Biofilm formation was observed in 76% of all isolates. Conclusions: The MLP typing serves as a valuable technique for analyzing the genetic composition of A. flavus isolates. A notable degree of genetic diversity (49 genotypes) was identified among the evaluated isolates. Of all the antifungal agents assessed, voriconazole and caspofungin demonstrated the greatest in vitro effectiveness.