The yeast Malassezia pachydermatis, an opportunistic pathogen that inhabits the skin of various domestic and wild animals, is capable of producing a biofilm that plays an important role in antifungal resistance. The aim of this research study was to find the intensity of biofilm production by M. pachydermatis strains isolated from the ear canal of healthy dogs, and to determine the susceptibility of planktonic, adhered and biofilm-forming cells to three azole antifungals—itraco-nazole, voriconazole and posaconazole— that are most commonly used to treat Malassezia infections. Out of 52 isolates, 43 M. pachydermatis strains (82.7%) were biofilm producers with varying levels of intensity. For planktonic cells, the minimum inhibitory concentration (MIC) range was 0.125–2 µg/mL for itraconazole, 0.03–1 µg/mL for voriconazole and 0.03–0.25 µg/mL for posaconazole. Only two isolates (4.7%) were resistant to itraconazole, one strain (2.3%) to voriconazole and none to posaconazole. For adhered cells and the mature biofilm, the following MIC ranges were found: 0.25–16 µg/mL and 4–16 µg/mL for itraconazole, 0.125–8 µg/mL and 0.25–26 µg/mL for voriconazole, and 0.03–4 µg/mL and 0.25–16 µg/mL for posaconazole, respectively. The least resistance for adhered cells was observed for posaconazole (55.8%), followed by voriconazole (62.8%) and itraconazole (88.4%). The mature biofilm of M. pachydermatis showed 100% resistance to itraconazole, 95.3% to posaconazole and 83.7% to voriconazole. The results of this study show that higher concentrations of commonly used antifungal agents are needed to control infections caused by biofilm-forming strains of M. pachydermatis.

The aim of this study was to reveal the potentially genotoxic effect of zearalenone on bovine lymphocytes by comet assay in vitro. The bovine lymphocytes were exposed to various zearalenone concetrations (50; 10; 2; 0.4 and 0.08 ppm). The viability and DNA damage of lymphocytes was monitored after 2 h, 24 h, 48 h and 72 h. After 2 hours of zearalenone exposure, statistically significant DNA damage occurred at all tested concentrations of 0.08 ppm (12.2±1.25; p<0.05), 0.4 ppm (12.7±0.88; p<0.01), 2 ppm (12.0±0.51; p<0.01), 10 ppm (11.2±0.47; p<0.01) and at 50 ppm (14.2±0 61; p<0.001). Significantly greater DNA damage was also found after 24 h, 48 h and 72 h. The obtained results showed that zearalenone may induce DNA damage of the bovine lymphocytes.

A current problem in candidiasis treatment is increasing resistance to azoles, which are often prescribed to patients. The study underlines the high resistance of yeasts to fluconazole, which achieved high MIC (minimal inhibitory concentration) values both alone and in combination with essential oils (EOs). Antifungal activity of Hyssopus officinalis, Thymus vulgaris, Salvia officinalis and Rosmarinus officinalis EOs was determined against 13 clinical isolates of Candida albicans and reference strain Candida albicans ATCC 10231. The synergistic effect was investigated for the combination of itraconazole and fluconazole with Hyssopus officinalis and Thymus vulgaris EOs. Based on the fractional inhibitory concentration index, the synergistic effect was achieved in all of the samples exposed to itraconazole with Hyssopus officinalis (FICI 0.3±0.06). On the other side, the additive effect was proven in use of itraconazole with Thymus vulgaris (FICI 0.75±0.35) and fluconazole with both EOs tested (FICI 0.81±0.19; 0.88±0.57) This study shows the importance of monitoring the synergistic effect of antifungals combined with EOs, because it is a possible solution for reducing the resistance and improving the disease prognosis.

In this study, the biodegradation of zearalenone (ZEN) by cell suspensions of various Lactobacillus species (Lb. fermentum 2I3 (L1), Lb. reuteri L26 (L3), Lb. plantarum L81 (L4), Lb. reuteri 2/6 (L5), Lb. plantarum CCM 1904 (L6)), Bacillus subtilis CCM 2794 (Bs), and Bacillus licheniformis CCM 2206 (Bl); was investigated in vitro. All lactobacilli cell suspensions showed very good degradation efficiency (57.9—100 %) for zearalenone at the concentration 0.01 ppm. At higher concentrations of zearalenone, their biodegradation activity decreased significantly (0—13.9 %). Bacillus subtilis CCM 2794 was able to degrade zearalenone at concentrations of: 0.01 ppm (100 %), 0.1 ppm (74.5 %), and at higher concentrations of ZEN (1 ppm; 10 ppm), the degradation was 11.7 % and 0 %, respectively. For Bacillus licheniformis CCM 2206, no biodegradation of zearalenone was observed at the concentration of 10 ppm, but slight degradation (4.5—8.8 %) was found at lower zearalenone concentrations.

Systemic fungal diseases and antifungal resistance represent a serious problem in human medicine and contribute to increased patient mortality. The most common causes of these diseases are opportunistic yeasts of the genus Candida. C. albicans is considered to be the main pathogen, together with C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei. Azole antifungals predominate in the treatment of the systemic mycoses. For antifungal resistance in Candida spp. some genes and their mutations are responsible, the genes ERG11, CDR1, CDR2 and MDR1 being considered the most important. The main target of azole antifungals is the process of ergosterol synthesis. Due to ergosterol crucial functions and its unique structural properties, the synthesis of ergosterol and its individual steps represent the target of most clinically available antifungals. The biofilm appears to be a significant virulence factor of the yeast Candida spp. It allows hematogenous dissemination of cells, prevents the effect of antifungals on all cells during treatment and leads to a high level of antimicrobial resistance. The antifungal resistance in candidiasis often has a multifactorial origin, which must be considered in the treatment of systemic mycoses and in the development of new antifungals.