Susceptibility of Malassezia pachydermatis Clinical Isolates to Allopathic Antifungals and Brazilian Red, Green, and Brown Propolis Extracts

Abstract

Clinical mycoses treatment is associated with issues such as negative side effects, high cost, prolonged treatment, and resistant strain selection. Malassezia pachydermatis is the most frequently isolated yeast in cases of canine otitis and dermatitis. The number of fungal strains exhibiting primary resistance to several drugs in vitro is increasing. Propolis has a diverse chemical composition and well-known therapeutic properties against mycoses. An alternative method for producing propolis extracts using supercritical fluid has higher selectivity, yielding extracts with fewer pollutant residues. This study therefore aimed to evaluate the in vitro susceptibility profile of M. pachydermatis clinical isolates to precharacterized supercritical and ethanolic extracts. Three types of Brazilian propolis extracts (green, red, and brown) and commercial allopathic antifungals were used in this investigation. We used the microdilution broth technique to evaluate the susceptibility profile of the yeasts. The minimum inhibitory concentration (MIC) of the brown propolis ethanolic extract was ≥16 µg/mL for all isolates. The MICs of fluconazole, ketoconazole, itraconazole, and amphotericin B ranged from 8 to >64 µg/mL, 0.032-4 µg/mL, 0.0313-16 µg/mL, and 1-2 µg/mL, respectively. The MICs of ethanolic red propolis extracts were lower than those of supercritical red propolis extracts. However, the green propolis ethanolic extract had more pronounced fungicidal activity. Isolates with lower susceptibility to commercial fungicides were inhibited by red and green propolis extracts. These results indicate that propolis can potentially be used in in vivo experiments as a promising therapeutic agent against M. pachydermatis infections.

New Insights for Red Propolis of Alagoas—Chemical Constituents, Topical Membrane Formulations and Their Physicochemical and Biological Properties

“…The propolis is a natural product complex formed by a mixture of wax, pollen, salivary secretions, resinous, gummy and balsamic substances collected from various plant sources and biotransformed by different species of bees [ 4 ]. In Brazil, there are 13 types of propolis and their classification is made according to geographic location, botanical origin, color and physicochemical proprieties [ 5 ].…”

Brazilian Brown Propolis: an Overview About Its Chemical Composition, Botanical Sources, Quality Control, and Pharmacological Properties

“…More than 70% of the strains used in this study were itraconazole resistant. Deegan et al ( 2019 ) compared the activity of BP ethanolic extract against Malassezia pachydermatis and some commercially antifungal agents. BP displayed a MIC value > 16 mg/ml, but it did not exhibit lethality (MFC) at the highest tested concentrations.…”

Comparison of the Biological Potential and Chemical Composition of Brazilian and Mexican Propolis

“…The increase in mycosis and the appearance of resistant fungal strains in patients has been increasingly observed throughout the world. This has generated the search and development of new compounds that meet the requirements of an antifungal and in that sense, Mexico and Brazil have studied the antifungal properties of ethanolic extracts of propolis in different species of yeast [104] and filamentous fungi [105,106].…”