Could the determination of Aspergillus fumigatus mating type have prognostic value in invasive aspergillosis?

The Emergence of New Sporothrix brasiliensis Genotypes in Current Epidemic of Sporotrichosis in Southeastern Brazil

BACKGROUND

Zoonotic sporotrichosis caused by Sporothrix brasiliensis has become the main subcutaneous mycosis in Brazil. Minas Gerais (MG) is located in southeast Brazil and since 2015 has experienced an epidemic of zoonotic sporotrichosis.

OBJECTIVES

This study aimed to reconstruct the epidemiological scenario of sporotrichosis from S. brasiliensis in recent epizooty in the Metropolitan Region of Belo Horizonte (MRBH), MG.

METHODS

A total of 95 Sporothrix spp. isolates (Sporothirx brasiliensis n = 74, S. schenckii n = 11 and S. globosa n = 10) were subjected to Amplified Fragment Length Polymorphism (AFLP) genotyping and mating-type analysis to determine genetic diversity and population structure. Of these, 46 S. brasiliensis isolates were recovered from animals (cats n = 41 and dogs n = 5) from MRBH.

RESULTS

Our study describes the high interspecific differentiation power of AFLP-based genotyping between the main phylogenetic Sporothrix groups. S. brasiliensis presents high genetic variability and pronounced population structure with geographically focused outbreaks in Brazil. The genetic groups include older genotypes from the prolonged epidemic in Southeast (Rio de Janeiro and São Paulo), South (Rio Grande do Sul), Northeast (Pernambuco) and new genotypes from the MRBH. Furthermore, we provide evidence of heterothallism mating strategy in pathogenic Sporothrix species. Genotypes originating in Rio de Janeiro and Pernambuco carry the predominant MAT1-2 idiomorph as opposed to genotypes from Rio Grande do Sul, which have the MAT1-1 idiomorph. We observed an overwhelming occurrence of MAT1-1 among MRBH isolates.

CONCLUSION

Our study provides clear evidence of the predominance of a genetic group profile circulating in animals in Minas Gerais, independent of that disseminated from Rio de Janeiro. Our data can help us understand the genetic population processes that drive the evolution of this fungus in Minas Gerais and contribute to future mitigation actions for this ongoing epidemic.

Strengthening the One Health Agenda: The Role of Molecular Epidemiology in Aspergillus Threat Management

The United Nations’ One Health initiative advocates the collaboration of multiple sectors within the global and local health authorities toward the goal of better public health management outcomes. The emerging global health threat posed by Aspergillus species is an example of a management challenge that would benefit from the One Health approach. In this paper, we explore the potential role of molecular epidemiology in Aspergillus threat management and strengthening of the One Health initiative. Effective management of Aspergillus at a public health level requires the development of rapid and accurate diagnostic tools to not only identify the infecting pathogen to species level, but also to the level of individual genotype, including drug susceptibility patterns. While a variety of molecular methods have been developed for Aspergillus diagnosis, their use at below-species level in clinical settings has been very limited, especially in resource-poor countries and regions. Here we provide a framework for Aspergillus threat management and describe how molecular epidemiology and experimental evolution methods could be used for predicting resistance through drug exposure. Our analyses highlight the need for standardization of loci and methods used for molecular diagnostics, and surveillance across Aspergillus species and geographic regions. Such standardization will enable comparisons at national and global levels and through the One Health approach, strengthen Aspergillus threat management efforts.

Insight into the Significance of Aspergillus fumigatus cyp51A Polymorphisms

Triazole antifungal compounds are the first treatment choice for invasive aspergillosis. However, in the last decade the rate of azole resistance among Aspergillus fumigatus strains has increased notoriously. The main resistance mechanisms are well defined and mostly related to point mutations of the azole target, 14-α sterol demethylase (cyp51A), with or without tandem repeat integrations in the cyp51A promoter. Furthermore, different combinations of five Cyp51A mutations (F46Y, M172V, N248T, D255E, and E427K) have been reported worldwide in about 10% of all A. fumigatus isolates tested. The azole susceptibility profile of these strains shows elevated azole MICs, although on the basis of the azole susceptibility breakpoints, these strains are not considered azole resistant. The purpose of the study was to determine whether these cyp51A polymorphisms (single nucleotide polymorphisms [SNPs]) are responsible for the azole susceptibility profile and whether they are reflected in a poorer azole treatment response in vivo that could compromise patient treatment and outcome. A mutant with a cyp51A deletion was generated and became fully susceptible to all azoles tested. Also, three cyp51A gene constructions with different combinations of SNPs were generated and reintroduced into an azole-susceptible wild-type (WT) strain (the ΔakuB^KU80 strain). The alternative model host Galleria mellonella was used to compare the virulence and voriconazole response of G. mellonella larvae infected with A. fumigatus strains with WT cyp51A or cyp51A with SNPs. All strains were pathogenic in G. mellonella larvae, although they did not respond similarly to voriconazole therapeutic doses. Finally, the full genomes of these strains were sequenced and analyzed in comparison with those of A. fumigatus WT strains, revealing that they belong to different strain clusters or lineages.