Y5 - Cutaneous fungal infection (incl. dermatophytosis, pityriasis versicolor) Flashcards
def of D
a superficial fungal infection with variable presentation depending on site
what are dermatophytes
fungal organisms which require keratin for growth
where can dermatophytes cause infection
in the hair, skin, and nails
how are dermatophytes spread
direct contact
what is the most common organism causing D
Tinea pedis
- most common superficial fungal infection
- 70% of adults
what is the most common superficial fungal infection
tinea pedis
what is onychomycosis
a superficial fungal infection affecting the nails
who does tinea capitis commonly affect
pre-adolescent children
who does tinea cruris commonly affect
adolescents and adult men
what are individuals with tinea barbae infection likely to have been in contact with
infected farm animals
what are anthropophilic organisms
spread from one person to another
what are geophilic organisms
spread from soil to humans
what are zoophilic organisms
spread from animals to humans
aetiology of D
the skins normal mechanism of protection (dryness and shedding of cells) may be interrupted by trauma, irritation, or maceration
host factors of D
genetic susceptibility (atopy) immunosuppression
local factors of D
sweating
occlusion
occupational exposure
what bacteria normally infects the nail
tinea unguium
signs and symptoms of D
RFs Hx of skin, hair, or nail lesion skin discomfort scalp lesions or alopecia red, scaling lesions of beard, moustache, limbs
what causes scalp lesions and alopecia
tinea capitis
what are RFs for D
exposure to infected people, animals, or soil chronic corticosteroid use hot weather obesity hyperhidrosis
investigations
potassium hydroxide microscopy
-hyphae (branching, rod-shaped filaments or uniform width with septa)
management for tinea capitis infection
systemic antifungal therapy -griseofulvin for >2yrs -terbinafine for >4yrs antifungal shampoo -selenium sulfide topical
management for tinea barbae, tinea manuum, or Majocchi’s granuloma
- griseofulvin
- terbinafine
management for tinea faciale, tinea corporis, or tinea pedis
topical allylamine antifungal therapy
-terbinafine
management for tinea unguium
systemic terbinafine therapy
-terbinafine
complications of D
kerion
-painful boggy scalp mass due to untreated tinea capitis
prognosis of D
good
-onychomycosis is most difficult to treat
def of PV
a common superficial fungal infection of the stratum corneum
what is pityriasis versicolor also known as
tinea versicolor
what causes PV
a change to the mycelial state of dimorphic yeasts of the genus malassezia
what does PV cause
hypo or hyperpigmented coalescing scaly macules on the trunk and upper arms
when is PV most common
in the summer months
epi of PV
common
adolescents and young adults
aetiology
a superficial fungal infection resulting from a change in the mycelial state of dimorphic lipophilic yeasts of the genus malassezia which colonise the stratum corneum and are normal skin flora
where are yeasts of malassezia commonly found
in rich sebaceous liquids
what are the most common malassezia species in PV
M globosa
M sympodialis
is PV contagious
no
what characterises PV
altered pigmentatin
signs and symptoms of PV
RFs
- asymptomatic
- dyspigmentation
- flat macules or patches
- more common over areas of high density sebaceous glands
what are RFs of PV
adolescence/young adults
greasy skin
hyperhidrosis
corticosteroid use
what is more common hypo or hyperpigmentation
hypopigmentation
what is common with hyperpigmented lesions
pityriasiform scale
investigations of PV
microscopy exam with KOH preparation
-short hyphae and budding yeast with spaghetti and meatballs appearance
management of PV
pyrithione zinc topical with UV light
complications of PV
dyschromia
-pigmentary abnormalities as treatment can take up to 6 weeks to resolve
prognosis
disease will persist if untreated
