Susceptibility of Malassezia pachydermatis to azole antifungal agents evaluated by a new broth microdilution method


  • Maria Lúcia Einchenberg UFRGS
  • Carin Elisabete Appel
  • Vanessa Berg
  • Adriana Cunha Muschner
  • Márcia de Oliveira Nobre UFRGS
  • Daniel da Matta Escola Paulista de Medicina
  • Sydney Hartz Alves UFSM
  • Laerte Ferreiro UFRGS



Susceptibilidade antifúngica, Malassezia pachydermatis, Microdiluição em caldo, Otite externa, Cetoconazol, Fluconazol, Itraconazol


Malassezia pachydermatis




is considered an opportunistic pathogen of the outer ear duct in dogs and cats. This yeast can also be found in the skin, rectum, anal sacks and vagina. Eighty-two samples of this yeast isolated from dogs with the symptoms of external otitis from the Porto Alegre region were tested for their susceptibility to antifungal agents using the Broth Microdilution Method. The testing antifungal agents were Ketoconazole, Fluconazole and Itraconazole. Experimental essays determined that Sabouraud dextrose broth supplemented with 1% Tween 80 was the most appropriate medium for culture, for a ten-fold dilutions for the inocula, and 48 hours as the interval of readings. The ranges of the Minimal Inhibitory Concentrations (MICs) for the 82 samples were (a) Ketoconazole, from 0.015 to 0.25 mg/mL (mean of 0.08 mg/mL), (b) Fluconazole, from 1 to 32 mg/mL (mean of 9.22 mg/mL), and (c) Itraconazole, from 0.007 to 0.125 mg/mL (mean of 0.05 mg/mL). The isolates of M. pachydermatis showed an excellent level of susceptibility to antifungal azole agents, with all strains being susceptible to Itraconazole, and with only 2.4 % and 3.7% being resistant to Fluconazole and Kketoconazole, respectively. The use of the broth microdilution method allows the assessment of the susceptibility of large numbers of samples from M. pachydermatis isolates to the most common antifungal agents. The proposed procedure is easy to perform and considerably inexpensive compared with other existing tests, which makes this a method of choice for laboratorial use. A standardization of procedures currently used in veterinary mycology laboratories is required. Consistent results among laboratories could greatly benefit the establishment of proper comparisons between studies on antifungal susceptibility and therapeutic trials.


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Author Biographies

Maria Lúcia Einchenberg, UFRGS

Carin Elisabete Appel

Fellowship students.

Vanessa Berg

Fellowship students.

Adriana Cunha Muschner

Fellowship students.

Márcia de Oliveira Nobre, UFRGS

Programa de Pós-Graduação em Ciências Veterinárias, FAVET/UFRGS.

Daniel da Matta, Escola Paulista de Medicina

Laboratório de Micologia Especial da Escola Paulista de Medicina, São Paulo, Brazil.

Sydney Hartz Alves, UFSM

Laboratório de Pesquisas Micológicas (LAPEMI) da Universidade Federal de Santa Maria (UFSM), Santa Maria, Brazil

Laerte Ferreiro, UFRGS

Setor de Micologia do Departamento de Patologia Clínica Veterinária (DPCV) - FAVET/UFRGS.



How to Cite

Einchenberg, M. L., Appel, C. E., Berg, V., Muschner, A. C., Nobre, M. de O., Matta, D. da, Alves, S. H., & Ferreiro, L. (2018). Susceptibility of Malassezia pachydermatis to azole antifungal agents evaluated by a new broth microdilution method. Acta Scientiae Veterinariae, 31(2), 75–80.




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