Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies.
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 disc diffusion methods are being performed. The aim was to evaluate the in vitro susceptibility of Malassezia yeast against antifungal agents using broth microdilution and disc diffusion methods, then to compare both methodologies. Fifty Malassezia isolates were studied. Microdilution method was performed as described in reference document and agar diffusion test was performed using antifungal tablets and discs. To support growth, culture media were supplemented. To correlate methods, linear regression analysis and categorical agreement was determined. The strongest linear association was observed for fluconazole and miconazole. The highest agreement between both methods was observed for itraconazole and voriconazole and the lowest for amphotericin B and fluconazole. Although modifications made to disc diffusion method allowed to obtain susceptibility data for Malassezia yeast, variables cannot be associated through a linear correlation model, indicating that inhibition zone values cannot predict MIC value. According to the results, disc diffusion assay may not represent an alternative to determine antifungal susceptibility of Malassezia yeast.
Departamento de Micología, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
Florencia D
FD
Rojas
Departamento de Micología, Instituto Nacional de Enfermedades Infecciosas, ANLIS "Dr. Carlos G. Malbrán", Buenos Aires, Chaco, Argentina.
Susana B
SB
Córdoba
Departamento de Micología, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
María
M
de Los Ángeles Sosa
Cátedra de Matemática Aplicada, Facultad de Humanidades, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
Laura C
LC
Zalazar
Departamento de Micología, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
Mariana S
MS
Fernández
Departamento de Micología, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
María E
ME
Cattana
Departamento de Micología, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
Liliana R
LR
Alegre
Departamento de Microbiología, ACIAM, Barcelona, Spain.
Alfonso J
AJ
Carrillo-Muñoz
Departamento de Micología, Instituto de Medicina Regional, Universidad Nacional del Nordeste, Resistencia, Chaco, Argentina.
Gustavo E
GE
Giusiano
D000362:Agar; D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D003470:Culture Media; D015725:Fluconazole / Q000494:pharmacology; D017964:Itraconazole / Q000494:pharmacology; D008290:Malassezia / Q000187:drug effects* / Q000254:growth & development; D008825:Miconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D065819:Voriconazole / Q000494:pharmacology
D000935:Antifungal Agents; D003470:Culture Media; D017964:Itraconazole; D008825:Miconazole; D000666:Amphotericin B; D015725:Fluconazole; D000362:Agar; D065819:Voriconazole
disc diffusion; lipid-dependent yeast; minimal inhibitory concentration