We studied 23 clinical and environmental strains of Sporothrix schenckii sensu lato collected from 1984 to 2017 in Argentina. The molecular identification (partial sequencing of a fragment of the calmodulin gene) of the strains was performed. For the yeast and mycelial phases, the in vitro susceptibility testing by a microdilution reference method was determined against eight antifungal drugs. Strains studied were identified as S. schenckii sensu stricto 13 (56.5%), S. brasiliensis 8 (34.7%) and S. globosa 2 (8.7%). The most active antifungal drugs tested for the yeast and mycelial phases expressed as geometric mean (GM) value of the minimal inhibitory concentration (MIC) (μg mL ) were terbinafine (0.07 and 0.24), posaconazole (0.13 and 0.58), itraconazole (0.38 and 1.10) and ketoconazole (0.22 and 0.89), while fluconazole (110.10 and 131.92) and flucytosine (2.96 and 79.03) were the less active. For voriconazole and amphotericin B the GM-MIC values were acceptably low for the yeast phase (0.39 and 0.72 μg mL ), while the mycelial phase showed values ≥2-fold higher (8.76 and 1.88 μg mL ), P < .05. Here, we described S. schenckii sensu stricto, S. brasiliensis and S. globosa, these species were isolated from humans, animals and soil and are circulating in Argentina since at least 1984.
The in vitro activities of three antifungal drugs alone and in combination were evaluated against five isolates of Cryptococcus neoformans using time-kill curves (TKC). The isolates were from AIDS patients who had either died or had failed to show a clinical response during amphotericin B (AMB) treatment. AMB, fluconazole (FCZ) and flucytosine (5FC), and combinations of the drugs (AMB plus 5FC, AMB plus rifampicin (RIF) and FCZ plus 5FC), were evaluated. With all five isolates AMB did not show fungicidal activity; instead, a persistent or tolerant effect was observed. Combinations of AMB plus 5FC and AMB plus RIF showed a clear synergic effect, except for one isolate tested with AMB plus RIF. In contrast, the FCZ plus 5FC combination did not inhibit growth of any isolate.
This is the first study using dog infection to assess the presence of endemic fungal pathogens in Argentina. Our results suggest that H. capsulatum is the main dimorphic fungal pathogen in the Interfluvio Teuco-Bermejito area. Therefore, the diagnosis of histoplasmosis should be taken into account in patients living in this geographic region who show pulmonary or mucocutaneous symptoms compatible with the disease.
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