D‐Glucosamine is an important building block of major structural components of the fungal cell wall, namely chitin, chitosan and mannoproteins. Other amino sugars, such as D‐mannosamine and D‐galactosamine, relatively abundant in higher eukaryotes, rarely occur in fungal cells and are actually absent from yeast and yeast‐like fungi. The glucosamine‐containing sugar nucleotide UDP‐GlcNAc is synthesized in yeast cells in a four‐step cytoplasmic pathway. This article provides a comprehensive overview of the present knowledge on the enzymes catalysing the particular steps of the pathway in Candida albicans and Saccharomyces cerevisiae, with a special emphasis put on mechanisms of the catalysed reactions, regulation of activity and perspectives for exploitation of enzymes participating in UDP‐GlcNAc biosynthesis as potential targets for antifungal chemotherapy. Copyright © 2006 John Wiley & Sons, Ltd.

Bacteria of the genus Staphylococcus are common pathogens responsible for a broad spectrum of human and animal infections and belong to the most important etiological factors causing food poisoning. Because of rapid increase in the prevalence of isolation of staphylococci resistant to many antibiotics, there is an urgent need for the development of new alternative chemotherapeutics. A number of studies have recently demonstrated the strong potential of peptidoglycan hydrolases (PHs) to control and treat infections caused by this group of bacteria. PHs cause rapid lysis and death of bacterial cells. The review concentrates on enzymes hydrolyzing peptidoglycan of staphylococci. Usually, they are characterized by high specificity to only Staphylococcus aureus cell wall components; however, some of them are also able to lyse cells of other staphylococci, e.g., Staphylococcus epidermidis-human pathogen of growing importance and also other groups of bacteria. Some PHs strengthen the bactericidal or bacteriostatic activity of common antibiotics, and as a result, they should be considered as component of combined therapy which could definitely reduced the development of bacterial resistance to both enzymes and antibiotics. The preliminary research revealed that most of these enzymes can be produced using heterologous, especially Escherichia coli expression systems; however, still much effort is required to develop more efficient and large-scale production technologies. This review discusses current state on knowledge with emphasis on the possibilities of application of PHs in the context of therapeutics for infections caused by staphylococci.

The antimicrobial activity of plant oils and extracts has been recognized for many years. In this study the activity of Thymus vulgaris, Citrus limonum, Pelargonium graveolens, Cinnamomum cassia, Ocimum basilicum, and Eugenia caryophyllus essential oils (EOs) distributed by Pollena Aroma (Nowy Dwór Mazowiecki, Poland) was investigated against a group of 183 clinical isolates of C. albicans and 76 isolates of C. glabrata. All of the oils exhibited both fungistatic and fungicidal activity toward C. albicans and C. glabrata isolates. The highest activity was observed for cinnamon oil, with MIC (Minimum Inhibitory Concentration) values in the range 0.002–0.125% (v/v). The MIC values of the rest of the oils were in the range 0.005% (or less) to 2.5% (v/v). In most cases MFC (Minimum Fungicidal Concentration) values were equal to MIC or twice as high. Additionally, we examined the mode of action of selected EOs. The effect on cell wall components could not be clearly proved. Three of the tested EOs (thyme, lemon, and clove) affected cell membranes. At the same time, thyme, cinnamon, and clove oil influenced potassium ion efflux, which was not seen in the case of lemon oil. All of the tested oils demonstrated the ability to inhibit the transition of yeast to mycelium form, but the effect was the lowest in the case of cinnamon oil.

The aim of our work was to check if one of the products of natural origin, namely honey bee propolis, may be an alternative or supplement to currently used antifungal agents. The activity of 50 ethanolic extracts of propolis (EEPs), harvested in Polish apiaries, was tested on a group of 69 clinical isolates of C. albicans. Most of the EEPs showed satisfactory activity, with minimum fungicidal concentrations (MFC) mainly in the range of 0.08–1.25% (v/v). Eradication of biofilm from polystyrene microtitration plates in 50% (MBEC₅₀, Minimum Biofilm Eradication Concentration) required concentrations in the range of 0.04% (v/v) to more than 1.25% (v/v). High activity was also observed in eradication of biofilm formed by C. glabrata and C. krusei on the surfaces of PVC (Polyvinyl Chloride) and silicone catheters. EEPs at subinhibitory concentrations inhibited yeast-to-mycelia morphological transformation of C. albicans in liquid medium and mycelial growth on solid medium. A synergistic effect was observed for the action of EEP in combination with fluconazole (FLU) and voriconazole (VOR) against C. albicans. In the presence of EEP at concentrations as low as 0.02%, the MICs of FLU and VOR were 256 to 32 times lower in comparison to those of the drug alone. Evidence for the fungal cell membrane as the most probable target of EEPs are presented.