Low genotypic diversity and first reports of clinical Sporothrix from retrospective samples in South Africa

Abstract

Sporotrichosis is a fungal infection caused by Sporothrix species. Some of the largest outbreaks of this disease have been recorded in South Africa, and the country is considered an endemic region for the pathogen. Previous work in the 1990s considered the etiological agents of the disease, with strains stored in various culture collections. In this study, we reconsidered the identity of these strains by polymerase chain reaction amplification and sequencing of three gene regions (ITS, BenA, and CaM) and assessed their genetic diversity by microsatellite typing. The results showed that the population included four species, S. schenckii (n = 69), S. globosa (n = 1), S. pallida (n = 1), and an uncharacterised taxon (n = 2). The mating type distribution of the S. schenckii population was predominantly of the MAT1-2 idiomorph (92%). Microsatellite markers revealed only four multi-locus genotypes, of which a single genotype represented 85% of the isolates. The results provide evidence for asexual proliferation of S. schenckii lineages in South Africa, and raise questions as to how they have been dispersed. Furthermore, the results highlight uncertainties regarding the relative significance of the other species reported here.

PLAIN LANGUAGE SUMMARY : Sporotrichosis is a mammalian cutaneous traumatic infection caused by pathogenic Sporothrix fungi. Using genetic markers, we report several Sporothrix species in South Africa for the first time, and reveal the wide distribution of a closely related genetic lineage in the country.