Part 1: Understanding the role of Malassezia spp. in skin disorders: Malassezia yeasts as commensal or pathogenic organisms of human and animal skin

ABSTRACT

Introduction

Malassezia spp. are a group of lipid-dependent basidiomycetes yeasts acting as commensal organisms of the human and animal skin. However, under some not well-defined circumstances, these yeasts may switch to opportunistic pathogens triggering a number of skin disorders with different clinical presentations. The genus comprises of 18 lipid-dependent species with a variable distribution in the hosts and pathologies thus suggesting a host- and microbe-specific interactions.

Area covered

This review highlighted and discussed the most recent literature regarding the genus Malassezia as a commensal or pathogenic organisms highlighting Malassezia-associated skin disorders in humans and animals and their antifungal susceptibility profile. A literature search of Malassezia associated skin disorders was performed via PubMed and Google scholar (up to May 2023), using the different keywords mainly associated with Malassezia skin disorders and Malassezia antifungal resistance.

Expert opinion

Malassezia yeasts are part of the skin mycobiota and their life cycle is strictly associated with the environment in which they live. The biochemical, physiological, or immunological condition of the host skin selects Malassezia spp. or genotypes able to survive in a specific environment by changing their metabolisms, thus producing virulence factors or metabolites which can cause skin disorders with different clinical presentations.

KEYWORDS:

• Antifungal resistance
• Atopic dermatitis
• Malassezia folliculitis
• pityriasis versicolor
• seborrheic dermatitis
• Malassezia spp
• skin disorders

Article highlights

• The assessment of the role of Malassezia yeasts in skin disorders which is still an object of debate and need more studies.

• Malassezia species are part of microbiota of human and animal skin.

• The Malassezia genus comprise of 18 species showing and host species specificity or a skin disorder specificity.

• The Malassezia colonization begin after birth and increases with the age.

• Malassezia spp. distribution vary according to the host geographical origin, body sites and pathology.

• Within individual spp. different genotypes were detected and they were associated with severity of Malassezia associated infection.

• Azole resistance phenomena were detected in some Malassezia spp. coming from hosts with skin disorders.

• The biochemical, physiological or immunological condition of the host skin select Malassezia spp. or genotypes able to survive in a specific environment that can drive the change of Malassezia metabolism, the production of virulence factors and the reduction of drug susceptibility.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.