New Clinical and Laboratory Standards Institute (CLSI)-endorsed epidemiological cut-off values (ECVs) for amphotericin B, itraconazole, terbinafine, and posaconazole, for the filamentous phase of Sporothrix brasiliensis, S. schenckii and S. globosa have been reported by dos Santos and colleagues. The percentage of non-wild-type (NWT, often resistant) isolates with minimum inhibitory concentrations (MICs) above the established ECVs was also determined for each drug and species. The findings are summarized in the table below.
Table 1. Epidemiological cutoff values for Sporothrix species and percentage non-wild type
| Sporothrix species | ECV (µg/mL) | %NWT |
| AmB | ||
| Sporothrix brasiliensis | 8 | 0 |
| Sporothrix schenckii | 4 | 2.3 |
| Sporothrix globosa | 8 | 3.1 |
| Posa | ||
| Sporothrix brasiliensis | 4 | 1.0 |
| Sporothrix schenckii | 4 | 19.5 |
| Sporothrix globosa | 4T | 7.5 |
| Itra | ||
| Sporothrix brasiliensis | 4 | 3.7 |
| Sporothrix schenckii | 4 | 8.3 |
| Sporothrix globosa | – | – |
| Terb | ||
| Sporothrix brasiliensis | 0.12 | 4.4 |
| Sporothrix schenckii | 0.5T | 0 |
| Sporothrix globosa | 0.2T | 0 |
A total of 3,504 MIC values for six antifungal agents (amphotericin B, itraconazole, posaconazole, voriconazole, isavuconazole, and terbinafine) were obtained from 19 international laboratories. Four of seven antifungals met the CLSI M57 guidelines criteria for determining ECVs. Overall, besides establishing validated ECVs for key antifungals against Sporothrix species complex, the study suggests antifungal resistance surveillance should start, given the significant proportion of Sporothrix schenckii isolates (19.5%) being NWT for posaconazole.
