Molecular-based assessment of diversity and population structure of Sporothrix spp. clinical isolates from Espirito Santo-Brazil

Background Sporotrichosis is a subcutaneous mycosis caused by Sporothrix species that affects humans and animals. Little information on the genetic diversity and population structure of the pathogen is available for Brazil, which is needed to design effective strategies to tackle the advance of sporotrichosis in endemic areas. Objectives We assessed the genetic diversity and mating-type distribution of Sporothrix isolates recovered from human and feline cases of sporotrichosis in Espirito Santo-Brazil to better understand the population structure, epidemiology and diversification of this pathogen, as well as to explore the possible routes of transmission involved in the ongoing outbreaks. Methods In all, 75 Sporothrix isolates were identified with phenotypic characteristics. Then, fungal DNA extraction was performed, and the species-specific PCR technique was applied, using markers directed to the calmodulin gene. The mating-type idiomorph of species was identified by PCR using primers targeting the MAT1-1 and MAT1-2 loci. Results Among the 75 Sporothrix isolates, 76% were confirmed as S brasiliensis and 24% as S schenckii sensu stricto. S brasiliensis was more prevalent in the metropolitan area and S schenckii s. str. in the mountainous region of the state. In both species, the presence of the two sexual idiomorphs was detected, suggesting that they are heterothallic species. Conclusions Our data suggest that sporotrichosis takes on an epidemic-urban character involving S brasiliensis. This species in Espirito Santo is likely to originate from Rio de Janeiro, as most isolates harbour the same MAT 1-2 locus. We confirm that S brasiliensis has significantly broadened its area of occurrence, an essential feature of emerging pathogens.

Automated summary

This study assessed the genetic diversity and mating-type distribution of Sporothrix isolates recovered from human and feline cases of sporotrichosis in Espirito Santo, Brazil. The results showed that S brasiliensis was more prevalent in urban areas, likely originating from Rio de Janeiro, and has significantly broadened its area of occurrence. The presence of both sexual idiomorphs in both species suggests they are heterothallic, indicating a potential for genetic diversification and adaptation in these emerging pathogens.