Virulence factors of Malassezia strains isolated from pityriasis versicolor patients and healthy individuals

Abstract

Over the last decade, Malassezia species have emerged as increasingly important pathogens associated with a wide range of dermatological disorders and bloodstream infections. The pathogenesis of Malassezia yeasts is not completely clear, but it seems to be strictly related to Malassezia strains and hosts and needs to be better investigated. This study aimed to assess the enzymatic activities, biofilm formation and in vitro antifungal profiles of Malassezia spp. from pityriasis versicolor (PV) and healthy patients. The potential relationship between virulence attributes, the antifungal profiles and the origin of strains was also assessed. A total of 44 Malassezia strains isolated from patients with (n = 31) and without (n = 13) PV were employed to evaluate phospholipase (Pz), lipase (Lz), and hemolytic (Hz) activities and biofilm formation. In addition, in vitro antifungal susceptibility testing was conducted using the CLSI broth microdilution with some modifications. A high percentage of strains produced Pz, Lz, Hz and biofilm regardless of their clinical origin. The highest number of strains producing high enzymatic activities came from PV patients. A correlation between the intensity of hydrolytic activities (Lz and Pz activities) and the Hz activity was detected. Positive associations between Lz and the low fluconazole susceptibility and Hz and biofilm formation were observed. These results suggest that enzyme patterns and biofilm formation along with antifungal profiles inter-play a role in the pathogenicity of Malassezia spp. and might explain the implication of some Malassezia spp. in invasive fungal infections and in the development of inflammation.

Lay summary: There is still little information on the virulence factors of Malassezia spp., despite their implication in severe diseases. Phospholipase, lipase, and hemolytic activities, biofilm formation and decreased antifungal susceptibility seem to contribute to their virulence in susceptible hosts.

Keywords: Malassezia species; pityriasis versicolor; antifungal susceptibility; healthy individuals; virulence factors.