Peer-reviewed veterinary case report
Malassezia yeast antifungal resistance and virulence in dogs and cats
By Brilhante, Raimunda Sâmia Nogueira et al.·Published in Veterinary microbiology·2018·Department of Pathology and Legal Medicine, Brazil·View original on PubMed →
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Original publication title: Malassezia pachydermatis from animals: Planktonic and biofilm antifungal susceptibility and its virulence arsenal.
Plain-English summary
A study found that the yeast Malassezia pachydermatis, which can cause ear infections and skin issues like seborrheic dermatitis in dogs and cats, has various levels of resistance to antifungal medications. Researchers tested 25 strains of this yeast and discovered that while some antifungals like ketoconazole and fluconazole were effective, all strains were strong at forming biofilms, which can make infections harder to treat. The yeast also produced harmful substances that can increase its ability to cause disease. This highlights the importance of effective treatment options for pets suffering from infections caused by this yeast.
People also search for: dog ear infection treatment · cat skin problems antifungal · Malassezia pachydermatis in pets
Abstract
The yeast Malassezia pachydermatis is a component of the microbiota of dogs and cats, however it can cause otitis and seborrheic dermatitis in these animals. The objective of this study was to determine the antifungal susceptibility, and evaluate virulence and pathogenicity of 25 M. pachydermatis strains from animals. Susceptibility to ketoconazole, fluconazole, itraconazole, voriconazole, terbinafine, and amphotericin B was evaluated by broth microdilution assay. In addition, biofilm-forming ability, protease, phospholipase, hemolysin and melanin production and adhesion to epithelial cells by this yeast species were assessed. Finally, strain pathogenicity was investigated using the nematode Caenorhabditis elegans. Concerning the planktonic susceptibility, minimum inhibitory concentrations varied from <0.03 to>64 μg/mL for azole derivatives, 1 to >16 μg/mL for amphotericin B and 0.03 to 0.25 μg/mL for terbinafine. All strains were classified as strong biofilm producers, and ketoconazole, fluconazole and amphotericin B presented the best inhibitory effect against mature biofilms. All fungal isolates produced proteases, whereas 14/25 strains were positive for phospholipase production. Hemolytic activity was not observed and 18/25 strains showed dark pigmentation in the presence of L-DOPA. Regarding adhesion to epithelial cells, a low adhesion rate was observed in 10/12 evaluated strains. C. elegans mortality rate reached 95.9% after 96 h of exposure of the worms to M. pachydermatis. This yeast species produces important virulence factors and presents high pathogenicity, corroborating its clinical importance.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/29885800/