2023 Volume 72 Issue 2 Pages 191-196
Malassezia is a yeast-like fungus that is endemic to human and animal skin. It can be pathogenic bacteria for various diseases such as tinea versicolor, Malassezia folliculitis, seborrheic dermatitis, atopic dermatitis, and others. Malassezia is a lipid-requiring fungus and difficult to isolate by conventional culture methods. The morphological and biochemical findings of Malassezia spp. are similar, making it very difficult to identify the species on the basis of phenotype alone. Therefore, molecular biological methods to identify fungi at the species level are used, but few laboratories are available. Recently, selective culture media have been developed, allowing for easy cultivation. However, there are only a few studies on the analysis of the isolation of Malassezia in detail. In this study, we analyzed the frequency of isolation, identification of fungi at the species level by molecular biological methods, and detection of fungi in various types of the sample using a selective culture medium. The results showed a ninefold increase in the separation frequency when using the selective medium compared with cultivation in the olive oil-stratified medium. Malassezia spp. were detected in five types of sample: otorrhea (20/43), skin (10/43), nasal swabs (9/43), sputum (3/43), and eye discharge (1/43) using 43 clinical isolates and preserved strains. All the Malassezia spp. detected were identified at the species level using molecular biological techniques. These results indicate that the selective medium increases the frequency of fungal isolation and, when combined with molecular biological techniques, identifies the species. In the future, it will be necessary to further improve the culture method and establish a simple and rapid identification method using a mass spectrometer.
