Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies

FLORENCIA D. ROJAS; SUSANA B. CORDOBA; MARIA DE LOS A. SOSA; LAURA C. ZALAZAR; MARIANA S. FERNÁNDEZ; MARÍA E. CATTANA; LILIANA R. ALEGRE; ALFONSO J. CARRILLO-MUÑOZ; GUSTAVO E. GIUSIANO

MYCOSES

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 60 p. 104 - 111

0933-7407

All Malassezia species are lipophilic, thus modifications are required in susceptibility testing methods to ensure their growth. Antifungal susceptibility of Malassezia species using agar and broth dilution methods has been studied. Currently, few tests using disk diffusion methods are being performed. Objectives: The aim of this study was to evaluate the in vitro susceptibility profile of Malassezia yeasts against antifungal agents using broth microdilution and disk diffusion methods, then to compare both methodologies. Fifty Malassezia isolates were studied. Broth microdilution method was performed as described in a reference document and an agar disk diffusion test was performed using antifungal tablets and disks. To support growth of these yeasts culture media were supplemented. To correlate both methods, linear regression analysis was performed and categorical agreement was determined. The strongest linear association was observed for fluconazole and miconazole. The highest agreement between both methods was observed for ITZ and VCZ and the lowest for AMB and FLC. Although modifications made to disk diffusion method allowed to obtain susceptibility data for Malassezia yeasts, variables cannot be associated through a linear correlation model, indicating that inhibition zone values cannot predict MIC value. According to the data obtained in this study, disk diffusion assay may not represent an alternative to determine antifungal susceptibility of Malassezia yeasts.