Sporothrix brasiliensis, S. globosa, and S. mexicana, three new Sporothrix species of clinical interest

Abstract

Sporothrix schenckii is the species responsible for sporotrichosis, a fungal infection caused by the traumatic implantation of this dimorphic fungus. Recent molecular studies have demonstrated that this species constitutes a complex of numerous phylogenetic species. Since the delineation of such species could be of extreme importance from a clinical point of view, we have studied a total of 127 isolates, most of which were received as S. schenckii, including the available type strains of species currently considered synonyms, and also some close morphological species. We have phenotypically characterized all these isolates using different culture media, growth rates at different temperatures, and numerous nutritional tests and compared their calmodulin gene sequences. The molecular analysis revealed that Sporothrix albicans, S. inflata, and S. schenckii var. luriei are species that are clearly different from S. schenckii. The combination of these phenetic and genetic approaches allowed us to propose the new species Sporothrix brasiliensis, S. globosa, and S. mexicana. The key phenotypic features for recognizing these species are the morphology of the sessile pigmented conidia, growth at 30, 35, and 37 degrees C, and the assimilation of sucrose, raffinose, and ribitol.

FIG. 1.

One of the 5,000 most parsimonious trees obtained from heuristic searches based on analysis produced from the combined data set. Bootstrap support values above 90% are indicated at the nodes. Type strains are indicated with boldface type.

FIG. 2.

Morphology of the sessile conidia of the S. schenckii species complex. (A) S. brasiliensis CBS 120339 (clade I). (B and C) S. schenckii (clade II) and FMR 8608 (clade IIa) (B) and FMR 8677 (clade IIb) (C). (D) S. globosa CBS 120340 (clade III). (E) S. mexicana CBS 120341 (clade IV). Bars, 10 μm.