EVALUATION OF ETEST AND BROTH MICRODILUITION METHODS FOR ITRACONAZOLE SUSCEPTIBILITY TESTING OF Sporothrix schenckii

Abstract

The frequent occurrence of resistant isolated fungi against antifungal drugs stimulated advances in the antifungigram techniques, which were standardized by CLSI. However, the methods have been inefficient and impractical to be executed in clinical laboratories. Within this context, commercial techniques have been developed, being ETEST one of them. ETEST has proved to be easier to execute when compared to the techniques approved by the CLSI. This study used the ETEST and the microdilution method, performed according to CLSI, for determining the in vitro susceptibility of isolates of Sporothrix schenckii against itraconazole. The CLSI uses RPMI 1640 medium and the reading of MIC after the period of incubation of 72h at 35ºC. MIC was determined by the ETEST, being Sabouraud dextrose agar used as medium, and the reading performed after 72 hours of incubation at 35ºC. The variance analysis, analyzed by T-paired test, did not demonstrate statistical differences among the CIM values obtained by the microdilution technique in broth (MIC among 0.219 and 0.875 µg/mL) and ETEST (MIC among 0.032 and 2.0 µg/mL). However, the correlation coefficient (R) was negative, probably because of the small number of samples. These results show the necessity of further studies to assess the application of ETEST to evaluate the susceptibility of S. schenckii against the itraconazol.

KeyWords: Broth microdiluition, sporotrichosis, Sporothrix schenckii, susceptibility.