''Malassezia furfur'' (formerly known as ''Pityrosporum ovale'') is a species of

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

(a type of

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

) that is naturally found on the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

surfaces of humans and some other mammals. It is associated with a variety of dermatological conditions caused by fungal infections, notably

seborrhoeic dermatitis Seborrhoeic dermatitis (also spelled seborrheic dermatitis in American English) is a long-term skin disorder. Symptoms include flaky, scaly, greasy, and occasionally itchy and inflamed skin. Areas of the skin rich in oil-producing glands are ...

and

tinea versicolor Tinea versicolor (also pityriasis versicolor) is a condition characterized by a skin eruption on the trunk and proximal extremities. The majority of tinea versicolor is caused by the fungus '' Malassezia globosa'', although '' Malassezia furfur' ...

. As an opportunistic pathogen, it has further been associated with

dandruff Dandruff is a skin condition of the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, is known as s ...

, malassezia folliculitis,

pityriasis versicolor Pityriasis commonly refers to flaking (or scaling) of the skin. The word comes from the Greek πίτυρον 'bran'. Classification Types include: * Pityriasis alba, dry, fine-scaled, pale patches on the face * Pityriasis lichenoides chronica, c ...

(alba), and malassezia

intertrigo Intertrigo, commonly called “skin fold dermatitis”, refers to a type of inflammatory rash (dermatitis) of the superficial skin that occurs within a person's body folds. These areas are more susceptible to irritation and subsequent infection d ...

, as well as catheter-related fungemia and

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

in patients receiving

hematopoietic Haematopoiesis (; ; also hematopoiesis in American English, sometimes h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells. In a healthy adult human, roughly ten ...

transplants.

Background

''Malassezia furfur'' is a fungus that lives on the superficial layers of the

dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...

. It generally exists as a

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit f ...

organism forming a natural part of the human skin

microbiota Microbiota are the range of microorganisms that may be commensal, mutualistic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found ...

, but it can gain pathogenic capabilities when morphing from a

to a hyphal form during its life cycle, through unknown molecular changes. This can lead to its uncontrolled proliferation and a subsequent imbalance of the residential skin flora. Some

virulence factor Virulence factors (preferably known as pathogenicity factors or effectors in botany) are cellular structures, molecules and regulatory systems that enable microbial pathogens (bacteria, viruses, fungi, and protozoa) to achieve the following: * c ...

s or properties which may increase the fungus' ability to acquire an infectious nature include the formation of

biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...

s, increased adherence to surfaces, and hydrophobicity and also can form hyphae (long, cylindrical filaments) Infections with pathogenic ''M. furfur'' occur on the trunk or the limbs and present clinically as pigmented

macule A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this sys ...

s that can merge in the form of scaling plaques. Many of these lesions resolve spontaneously in most patients. The pathogen most frequently affects children compared to people of other age groups. It has been associated with numerous dermatological conditions, including

, and tinea circinata, all of which affect the skin. Some other diseases can also arise due to an infection with the fungus, such as catheter-related fungemia and

in patients receiving hematopoietic cell transplants.

Morphology and characteristics

''Malassezia furfur'' is a unicellular organism which varies in size between 1.5 and 4.5 × 2.0–6.5

micrometers The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

. The cells have a bottle-like shape due to a small protrusion visible at the end of each cell. Cells are difficult to grow in a lab since they require specific conditions.

Treatment

Topical application of

antifungal medication An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cry ...

s such as

ketoconazole Ketoconazole, sold under the brand name Nizoral, among others, is an antiandrogen, antifungal drug, antifungal, and antiglucocorticoid medication used to treat a number of fungal infections. Applied to the skin it is used for fungal skin inf ...

, cyclopirox olamine, piroctone olamine,

zinc pyrithione Zinc pyrithione (or pyrithione zinc) is a coordination complex of zinc. It has fungistatic (inhibiting the division of fungal cells) and bacteriostatic (inhibiting bacterial cell division) properties and is used in the treatment of seborrhoeic ...

, or sulfur compounds are commonly prescribed to treat diseases caused by ''Malassezia furfur''.

References

Bibliography

* {{Taxonbar, from=Q311343 Mycosis-related cutaneous conditions Fungal pathogens of humans Parasitic fungi Yeasts Fungi described in 1853 Fungus species