Infection: Species Malassezia Part -2

Predisposig factors

• Factors responsible for mycelial transition : warm, humid environment, oral contraceptive use, heredity, systemic corticosteroid, immunosuppression, hyperhidrosis, occlusion, malnourished state, Diabetes mellitus, Cushing disease, occlusion dressing & antibiotic therapy.

• The increase in humidity, temperature, and CO2 tension appear to be important factors that make the skin susceptible to infection.

Gupta AK et al: Skin diseases associated with Malassezia species. J Am Acad Dermatol 51:785, 2004Gupta AK, Bluhm R, Summerbell R: Pityriasis versicolor. J Eur Acad Dermatol Venereol 16:19, 2002

PV in Children

• M. pachydermatis- neonate

• M. sympodialis with neonatal cephalic pustulosis

Hypopigmentation in PV

• Malassezia synthesizes compound Pityriacitrin that absorbs ultraviolet light.

• Metabolites: Azaleic acid, & Dicarboxylic acid cause hypopigmentation by inhibiting tyrosinase and injuring melanocytes.

Microscopically: Malassezia sp.

• Have long and short septate.

• Occasionally branching hyphae with a “spaghetti and meatballs” appearance

Number of Pityrosporum in skin

• Malassezia furfur is abundant in normal skin (504,000 organisms/cm2 vs. 922,000 in individuals with dandruff and 665,000 in patients with seborrheic dermatitis).

Colour of TV

• Malassezia synthesizes pityriacitrin that absorbs ultraviolet light.

•

• Metabolites like as azaleic acid, a dicarboxylic acid, cause hypopigmentation by inhibiting tyrosinase and injuring melanocytes.

Mayser P et al: Pityriacitrin—an ultraviolet-absorbing indole alkaloid from the yeast Malassezia furfur. Arch Dermatol Res 294:131, 2002

Pathogenesis

• Ability of Malassezia to produce phospholipase, which directly correlates with skin infection.

D D

• IGH

• Guttate LSA• Epidermodyplasia verrusiformis• Erythrasma

• Evolving PRP

Infection: Species Malassezia Part -3Coming soon

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