Bimodal distribution of azole susceptibility in Sporothrix brasiliensis isolates in Brazil

is an emerging zoonotic fungal pathogen that can be difficult to treat. Antifungal susceptibility testing was performed on the mold phase of a convenience sample of 61 spp. isolates from human and cat sporotrichosis cases in Brazil using the Clinical and Laboratory Standards Institute standard M38. A bimodal distribution of azole susceptibility was observed with 50% (28/56) of isolates showing elevated itraconazole minimum inhibitory concentrations ≥16 µg/mL. Phylogenetic analysis found the resistant isolates were not clonal and were distributed across three different clades. Single nucleotide polymorphism (SNP) analysis was performed to identify potential mechanisms of resistance. Two of the 28 resistant isolates (MIC ≥16 mg/L) had a polymorphism in the cytochrome P450 gene, , corresponding to the well-known G448S substitution inducing azole resistance in . SNPs corresponding to other known mechanisms of azole resistance were not identified in the remaining 26 resistant isolates.