Fungal Infections in Macular Rash

Question 1

Malassezia fufur

Answer 1

Fungal Infections in Macular Rash
• *dimorphic fungus
• *lipophilic
• human reservoir
• normal microbiota 90-100% adults
• skin, hair follicles
• overgrowth under certain conditions including oily skin, warm humid climate, glucocorticoid treatment
• *not a dermatophyte even though disease called tinea versicolor
- causes * Tinea versicolor = pityriasis versicolor
• benign infection of keratinized epithelial cells in stratum corneum
– induration and scaling
• superficial hyper- or hypopigmented macules or patches, usually trunk
– pigments range from pink to yellow-brown
LAB/DIAGNOSIS
• lipid requirement in media (steroid olive oil)
• skin scrapings→ KOH→ +/- stain→ **“spaghetti and meatballs”

Question 2

Dermatophytoses

Answer 2

Fungal Infections in Macular Rash
• filamentous fungi
o branching, septate hyphae
o size, shape, structure, abundance, arrangement of asexual conidia diagnostic
o not normal microbiota, found in soil, animals
• many species w/in 3 genera: Microsporum (hair, skin), *Trichophyton (hair, skin, nap; most common), Epidermophyton (skin, nail)
- causes *TINEAS
• most common fungal infections of humans
VIRULENCE
• carbohydrate-specific adhesins: attachment to epithelial cells
• *keratinolytic- keratinases (most famous virulence factor)
DIAGNOSIS
- Microsporum canis fluoresces (blue-green) w/ Wood lamp
• skin biopsies -all dermatophytes gross morphology similar
o septate hyphae
o chains of conidia
• microscopic appearance of conidia in KOH preparations
o *size, shape, structure, abundance, arrangement of *asexual conidia diagnostic

Question 3

Hortaea weneckii

Answer 3

Fungal Infections in Macular Rash
• (dimorphic/polymorphic) fungus
• *black-pigmented
• *Halophilic (love salt)
• mostly tropics, subtropics
• soil, plants
• direct inoculation
CAUSES
• solitary, irregular, brown to black macule
• usually *palms, soles