The antifungal activities of 14 selected essential oils (at the concentrations of 0.5 %, 5 %, and 30 %) against the yeast Malassezia pachydermatis (18 isolates and one reference strain) were investigated. The isolates of M. pachydermatis were obtained from swabs of external ear canals of healthy dogs using sterile swabs. The determination of the efficacy was based on a modified disc diffusion method (CLSI M44-A2). The best antifungal efficacy (100 %) was shown by clove, cinnamon and oregano at the concentration of 30 %; less significant efficacy was shown at the concentration of 5 % (38 %, 33 % and 5 %, respectively). Satureja inhibited the growth of Malassezia (efficacy of 16 %) only at the concentration of 30 %. Bergamot, lavender, juniper, cedar, sage, tea-tree, grapefruit, pine, chamomile and yarrow essential oils were not able to form inhibition zones as defined in the methodology used (greater or equal to 15 mm) in all concentrations used. Therefore, according to the interpretation criterion, they were considered ineffective. In all cases, the concentration of 0.5 % was not effective against the growth of Malassezia yeasts.

Yeasts from the genus Malassezia belongs to normal commensal skin flora of warm-blooded vertebrates. These yeasts may act as opportunistic pathogens and cause skin diseases in humans and animals under certain conditions. The identification of Malassezia species is based on the phenotypic or genotypic diagnostics. The methods used for the phenotypic identification is determined by: the growth on Sabouraud agar, growth on selective media (Leeming-Notman agar, Dixon agar, Chrom Malassezia agar), the ability to utilise different concentrations of Tween, monitoring of the growth on CEL agar (soil enriched with castor oil) and TE agar (Tween-esculine agar), and the catalase test. The genotypic identification uses molecular methods like: the pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), amplified fragment lenght polymorphism (AFLP), denaturing gradient gel electrophoresis (DGGE), and the DNA sequence analysis.

The Malassezia genus is represented by several lipophilic yeasts, normally present on the skin of many warm-blooded vertebrates, including humans. The aim of this study was to investigate the occurrence of Malassezia yeasts in dogs with skin lesions (dermatitis, interdigital dermatitis and inflammation of anal sacs) and otitis externa. The presence of Malassezia spp. was investigated in a group of 300 dogs exhibiting clinical manifestations. The isolates of Malassezia were identified by using phenotypic (biochemical-physiological and morphological characteristics) and genotypic methods (PCR, RFLP-AluI, BanI and MspA1I) which allowed their precise identification. Malassezia yeasts were isolated from 84 specimens obtained from 76 positive dogs. M. pachydermatis was the most frequently isolated species (79 isolates) in this study. M. furfur was identified in four dogs and M. nana in one dog. The prevalence of isolated Malassezia spp. was 25.3 % in dogs with skin lesions; from which 36.0 % were dogs suffering from otitis externa, 24.5 % from dogs having dermatitis, 16.4 % from dogs with interdigital dermatitis and 14.3 % from dogs having inflammation of the anal sacs. A higher prevalence of Malassezia spp. was observed in animals with pendulous ears in comparison with dogs having erect ears.

The genus Malassezia belongs to Basidiomycota and includes 16 species, from which M. pachydermatis is the most common in dogs. M. pachydermatis is a member of the normal mycobiota of the skin and mucosal sites of dogs. Under certain conditions, these yeasts can be opportunistic pathogens and involved skin and ear canal infections of these animals. Topical and oral antifungal agents are used for the therapy of Malassezia dermatitis and otitis. With the expanding use of antifungal agents, resistant strains of Malassezia are increasingly detected. In this study, the susceptibility of 40 M. pachydermatis isolates to fluconazole, itraconazole, ketoconazole, clotrimazole and nystatin were evaluated in vitro based on the modified standard disk diffusion method M44-2A.

The cereals are a suitable substrate for the growth of microscopic filamentous fungi. Micromycetes are capable of reducing the nutritional value of feedstuff and they can produce several mycotoxins. The most frequent genera of microscopic filamentous fungi are Fusarium, Penicillium, Alternaria and Aspergillus. The contamination by microscopic fungi and mycotoxins was determinated in 56 samples of feed cereals originating from the Slovak Republic. The most common genera of fungi detected in the feed cereals included: Alternaria (67.8 %), Fusarium (44.6 %), Penicillium (39.2 %), Mucor (30.3 %), Rhizopus (28.5 %), Cladosporium (21.4 %), Scopulariopsis (8.9 %) and Aspergillus (1.7 %). Deoxynivalenol was present in 24 samples (42.8 %) and zearalenone in 15 samples (26.7 %). The values of both mycotoxins did not reach the regulatory limits and thus they do not pose a risk to livestock nutrition.