Urszula Czyzewska

Fatty acid profile and influence of oxythiamine on fatty acid content in Malassezia pachydermatis, Candida albicans and Saccharomyces cerevisiae.

Malassezia pachydermatis and Candida albicans are fungi involved in the skin diseases and systemic infections. The therapy of such infections is difficult due to relapses and problems with pathogen identification. In our study, we compare the fatty acids profile of M. pachydermatis, C. albicans and S. cerevisiae to identify diagnostic markers and to investigate the effect of oxythiamine (OT) on the lipid composition of these species. Total fatty acid content is threefold higher in C. albicans and M. pachydermatis compared with S. cerevisiae. These two species have also increased level of polyunsaturated fatty acids (PUFA) and decreased content of monounsaturated fatty acids (MUFA). We noted differences in the content of longer chain (>18) fatty acids between studied species (for example a lack of 20 : 1 in S. cerevisiae and 22 : 0 in M. pachydermatis and C. albicans). OT reduces total fatty acids content in M. pachydermatis by 50%. In S. cerevisiae, OT increased PUFA whereas it decreased MUFA content. In C. albicans, OT decreased PUFA and increased MUFA and SFA content. The results show that the MUFA to PUFA ratio and the fatty acid profile could be useful diagnostic tests to distinguish C. albicans, M. pachydermatis and S. cerevisiae, and OT affected the lipid metabolism of the investigated species, especially M. pachydermatis.

Comparison of lipid profiles of Malassezia pachydermatis strains isolated from dogs with otitis externa and without clinical symptoms of disease

Malassezia pachydermatis can cause infections of the skin and mucous membranes, especially in animals. It becomes a problem also in medicine. It is considered that metabolic disorders as well as hormonal and immunological status of the host promote diseases caused by M. pachydermatis. Here we consider whether specific features of fungi could also favour infections. We checked whether there are differences in lipid profiles between strains obtained from dogs with otitis externa and strains obtained from healthy dogs. Lipid profiles were determined using thin layer chromatography and gas chromatography–mass spectrometry. All analyses were carried out on 32 strains derived from dogs with otitis externa and 31 strains isolated from dogs without symptoms of disease. The results show that strains isolated from dogs without symptoms of otitis externa are characterised by a higher content of fatty acids. They contain significantly more behenic and lignoceric acids on medium without addition of lipids, and more oleic acid and total monounsaturated fatty acids on medium with lipids supplementation. These strains have also a higher content of esters of ergosterol and triglycerides. Data obtained show differences which may be specific features of M. pachydermatis‐specific strains related to the ability of infection, which could be not directly related of the host condition.

Thiamine antivitamins – an opportunity of therapy of fungal infections caused by Malassezia pachydermatis and Candida albicans

Severe skin diseases and systemic fungaemia are caused by Malassezia pachydermatis and Candida albicans respectively. Antifungal therapies are less effective because of chronic character of infections and high percentage of relapses. Therefore, there is a great need to develop new strategies of antifungal therapies. We previously found that oxythiamine decreases proliferation of yeast (Saccharomyces cerevisiae), therefore we suggest that thiamine antivitamins can be considered as antifungal agents. The aim of this study was the comparison of thiamine antivitamins (oxythiamine, amprolium, thiochrome, tetrahydrothiamine and tetrahydrooxythiamine) inhibitory effect on the growth rate and energetic metabolism efficiency in non‐pathogenic S. cerevisiae and two potentially pathogenic species M. pachydermatis and C. albicans. Investigated species were cultured on a Sabouraud medium supplemented with trace elements in the presence (40 mg l−1) or absence of each tested antivitamins to estimate their influence on growth rate, enzyme activity and kinetic parameters of pyruvate decarboxylase and malate dehydrogenase of each tested species. Oxythiamine was the only antivitamin with antifungal potential. M. pachydermatis and S. cerevisiae were the most sensitive, whereas C. albicans was the least sensitive to oxythiamine action. Oxythiamine can be considered as supportive agent in superficial mycoses treatment, especially those caused by species from the genus Malassezia.

Study on degradation process of famotidine hydrochloride in aqueous samples

The kinetics of famotidine (FAM) transformation under the influence of various factors, important from the environmental point of view, was investigated in aqueous solutions. The degradation processes using UV, H2O2, UV/H2O2, H2O2/Fe2+, and UV/H2O2/Fe2+ were studied. Direct photolysis and H2O2-assisted photolysis showed a pseudo-first-order kinetics, while the Fenton and the photo-Fenton processes fit second-order kinetics. The provided experiments proved a high resistance of FAM to direct photolysis. Its stability depends highly on the pH of the reaction solutions. The rate of FAM direct photolysis in acidic solutions was almost negligible. The reaction rate of FAM photolysis at pH 8–9 was 3.7 × 10−3 min−1 with DT50 about 3 h 7 min. It was found that the presence of H2O2 in the reaction environment enhances the rate of photolysis of FAM. The observed rates of reaction were 5.1 × 10−3 min−1 and 3.7 × 10−3 min−1 in acidic and basic solutions, respectively. The used Fenton systems appeared to be the most efficient in FAM removal. The rate of reaction depends on concentration of Fe2+ and H2O2. It was observed that the presence of UV-light enhances the reaction rate by two to six times in comparison to the classical Fenton system. Additionally, FAM behavior in natural water under solar irradiation was examined. The irradiation experiments were carried out in batch experiments with simulated sunlight.

Genetic relationships and population structure of Malassezia pachydermatis strains isolated from dogs with otitis externa and healthy dogs

ABSTRACT Malassezia pachydermatis causes infections of the skin and mucous membranes, especially in animals. It is commonly accepted that symptom manifestation depends on the physiological status of the host (different metabolic, hormonal, and immunological disorders). However, it should be considered whether distinct strains of M. pachydermatis could have different pathogenic potential and maintain opposite relations with the host, such as commensalism or parasitism. The scope of this study was to explore the population structure, genetic diversity, and phylogenetic relationships of M. pachydermatis strains isolated from dogs with clinical symptoms of otitis externa and from healthy dogs in order to investigate their relationships and evolutionary history. For all tests, a group of 30 strains derived from dogs with otitis externa and 34 strains from healthy dogs were used. The level of genetic diversity was initially assessed by polymerase chain reaction (PCR)-based random amplification of polymorphic DNA (RAPD-PCR), whereas evolutionary history was assessed by comparison of the nucleotide sequences of the internal transcribed spacer ITS1 region of nuclear rDNA. RAPD-PCR fingerprinting revealed a high level of genetic polymorphism in both tested groups (85% of unique profiles), but clinical isolates usually grouped together with other strains from otitis externa cases. Sequencing analysis identified 17 distinct genotypes with 59 polymorphic sites within both populations; however, putatively virulent strains were more closely related, indicating a probable correlation between the genotype and the virulence potential. Therefore, the hypothesis that M. pachydermatis virulence depends solely on the host’s properties should be reconsidered including evolutionary and epidemiological data.

Spores and vegetative cells of phenotypically and genetically diverse Bacillus cereus sensu lato are common bacteria in fresh water of northeastern Poland

Gram-positive rods Bacillus cereus sensu lato (sl) are common in natural habitats and food products. It is believed that they are restricted to spores; however, their ecology in aquatic habitats is still poorly investigated. Thus, the aim of the study was to assess the rain-dependent fluctuations in the concentration of B. cereus sl vegetative cells and spores, with evaluation of their phylogenetic and population structure in relation to the toxicity and psychrotolerance. We proved that vegetative cells of B. cereus sl are widely distributed in fresh water of rivers and lakes, being as common as spores. Moreover, heavy rain has a huge impact on their concentration in undisturbed environments. The diversity of B. cereus sl reflects the multiple sources of bacteria and the differences between their distinct environments. Next, their diverse genetic structure and phenotypes better fit their ecological properties than their taxonomic affiliation.