The effect of arachidonic acid on lipid metabolism and biofilm formation of two closely related Candida species

Candida albicans and C. dubliniensis are two closely related species that are important opportunistic pathogens causing serious infections. These serious infections are increasing because of the increase in immunocompromised patients. Candida albicans and C. dubliniensis share many phenotypic characteristics that make it difficult to differentiate between them, especially in a clinical sample. As a result several identification techniques, based on phenotypic characteristics, have been developed to differentiate between these Candida species. The aim of this study was to use current identification techniques to characterise selected C. albicans and C. dubliniensis strains in order to select strains that are phenotypically dissimilar. The methods used in this study include fluorescence on methylene blue agar plates, chlamydospore production on tobacco and sunflower seed husk agar plates, the germ tube test and growth at elevated temperatures. The growth of planktonic cells as well as biofilm production was also determined by the Klett-Summerson photoelectric colorimeter and by the use of crystal violet stain respectively. Virulence factors that have been studied include the production of hydrolytic enzymes i.e. lipase and phospholipase activity as well as the percentage hydrophobicity. The results obtained indicated that there is overlap in phenotypic characteristics of these species. However, it was possible to select three phenotypically dissimilar strains.