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infectious disease caused by Malassezia spp.
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Malassizia infection prepared by: Aras sulaiman A.supervised by: Dr. Asia A.
Introduction:
• Yeasts of the genus Malassezia (synonym: Pityrosporum)are obligatory or nonobligatory lipophilic, normal flora organisms of the skin of warm-blooded hosts.
• under appropriate conditions, they cause superficial infections of the skin and associated structures.
• The most commonly described human infection due to a member of the genus is pityriasis versicolor, a chronic, superficial disease of the stratum comeum layer of the epidermis containing the typical hyphal elements and yeast cells of Malassezia furfur in tissue .
• Malassezia yeasts were first described in the 19th century as budding yeasts found on the skin of patients with dandruff.
• They are named after Louis-Charles Malassez, a French scientist who identified the yeasts in the outer layer of the epidermis of patients with seborrheic dermatitis.
• The different Mal assezia species are distinguished based on their morphology, growth characteristics, enzyme activities, as well as by molecular methods . Malassezia are dimorphic fungi.
Distribution of Malassezia on normal skin • Malassezia are common lipid dependent fungi that
grow on the sebaceous areas of human skin, including the face, scalp, and upper trunk.
• Although Malassezia are a part of the normal human skin flora, they may also cause or exacerbate several skin diseases, including tinea versicolor, Pityrosporum folliculitis, and seborrheic dermatitis…
Scientific classification
Kingdom: Fungi
Division: Basidiomycota
Subdivision:Ustilaginomycotina
Class: Exobasidiomycetes
Order: Malasseziales
Family: Malasseziaceae
Genus: Malassezia
Scientific classification
Currently there are 11 recognized species:Malassezia dermatis Sugita et al., 2002.M. furfurM. globosaM. japonica Sugita et al., 2002. M. nanaM. obtusaM. pachydermatisM. restrictaM. slooffiaeM. sympodialisM. yamatoensis
Species
Description of the disease1- Pityriasis versicolor:• Pityriasis versicolor (PV) This is a chronic, superficial fungal
disease of the skin characterised by well-demarcated white, pink, beige, or brownish lesions, often combining.
• The colour varies according to the normal pigmentation of the patient, exposure of the area to sunlight, and the severity of the disease.
• The mycelial phase of the fungus is predominant in the lesions. M. globosa is the main species isolated from the lesions.
Etiological Agents: – Various species of Malassezia: • M. furfur • M. globosa • M. sympodialis • M. sloofiae • M. restricta
2-Dandruff• is excessive shedding of dead skin cells
(flakes) from the scalp in faster rate and in larger quantities than normal
• These flakes get trapped with oil, clump together and become noticeable
• The exact causes of dandruff are M. restricta
3-Seborrheic dermatitis
• Seborrheic dermatitis (SD): is a chronic dermatitis with greasy scales in seborrheic areas in children and adults.
• M. sympodialis and M. restricta are the Malassezia species found commonly in SD lesions.
4- Malassezia folliculitis
• : This is characterised by follicular papules and pustules localised to the back, chest and upper arms, sometimes the neck, and more seldom the face.
• These are itchy and often appear after sun exposure. Scrapings or biopsy specimens show numerous yeasts occluding the mouths of the infected follicules.
5-Fungaemia (Systemic infections caused by Malassezia).• Such patients may also develop small
embolic lesions in the lungs or other organs. • Diagnosis requires special culture media and
blood drawn back through the catheter is the preferred specimen. Culture of the catheter tip is also recommended
6-Confluent and reticulate papillomatosis
7-Neonatal cephalic pustulosis
• Previously considered as neonatal acne, it is a newly described benign clinical entity occurring in neonates. There is a non-follicular pustular eruption involving the face, neck and scalp.
8-Malassezia dermatitis in dogs
Risk factor Pregnancy Malnutrition Immunosuppression (including use of tumor
necrosis factor inhibitors) Oral contraception Excess heat and humidity (heavy clothing with
perspiration) Age: adolescents and young adults Skin: more common in people with naturally oily
or excessively sweaty skin
Diagnosis
• Morphology• Biochemical and cultural properties• Laboratory diagnosis
Treatment
• Ketoconazole
Selenium Sulfide for Dandruff and Seborrheic Dermatitis
Ciclopirox olamine cream
Miconazole Nitrate Cream
Tea Tree Oil Shampoo contains 2% pure Tea Tree Oil
Pyrithione Zinc 1%