Abstract:

Objective To investigate intraspecific and interspecific variation within Malassezia isolates from patients with pityriasis versicolor by random amplified polymorphic DNA （RAPD） analysis, to learn the difference between RAPD analysis and physiological and biochemical methods in the typing of Malassezia species, and to explore the relationship between RAPD patterns and Malassezia species. Methods A total of 47 Malassezia isolates were obtained from 34 patients with pityriasis versicolor, and they were classified into 5 species by morphological, physiological and biochemical features, i.e., M. furfur, M. obtusa, M. globosa, M. restricta and M. sympodialis. Genomic DNA was extracted from the 47 clinical isolates and 10 reference strains （including 7 species） of Malassezia. PCR was performed using 4 random primers including S22, S24, S25 and S33. RAPD patterns were analyzed by NTSYS software and dendrogram was autogenerated. Results Genomic DNA of most strains was successfully amplified with four primers, especially with primers S22 and S24 that resulted in rather stable and clear DNA bands. A total of 82 fragments were amplified from all tested strains. These strains showed both interspecific and intraspecific variation. Multiple strains were isolated from different body sites of 4 patients and identified into different species by biochemical and morphological typing; those strains from same hosts occupied contiguous positions in the dendrogram and exhibited a high genetic convergence. Conclusion The phenomenon that different strains from a co-host show a high genetic convergence indicates that species specificity and evolution of Malassezia are closely related to its hosts.