Isolation, identification and phenotypic characterization of clinical isolates of the Sporothrix schenckii Complex

Abstract

Sporotrichosis, caused by fungi belonging to the Sporothrix schenckii complex, is widely distributed around the globe, especially in tropical and subtropical regions. Traumatic inoculation is the usual route of acquisition. This infectious disease used to be restricted to farmers and armadillo’s hunters due to vegetable manipulation injuries. However, studies in Brazil have reported frequent outbreaks associated with feline transmission, characterizing sporotrichosis as a zoonotic infection. This study aimed to isolate, purify and evaluate in vitro virulence factors (colony growth and melanin production at different glucose concentrations), as well as, antifungal susceptibility testing to itraconazole (ITZ) and amphotericin B (AmB) of 40 clinical isolates obtained from patients living in Rio Grande do Norte state, Brazil. In our study, 75% of the patients were female and two clinical forms of infection were predominant, cutaneous-fixed and lymphocutaneous. We also report a case of primary pulmonary sporotrichosis leading to patient’s death. The molecular screening revealed that 12 strains were identified as S. brasiliensis. All the isolates were susceptible to both antifungal drugs tested, with MIC values ranging from 0.0312 to 0.5 μg/mL for ITZ and 0.125 and 1 μg/mL for AmB. There was no remarkable conclusion for colony growth, but a low number of strains produced melanin. Our study shows a prevalence of cases of sporotrichosis in female patients and S. brasiliensis as an etiological agent of infection in the region. In addition, the isolates demonstrated a satisfactory antifungal susceptibility profiling, with low MIC values to the antifungal drugs tested.