Skin disease and dermatophytes

Question 1

Pyogenic skin infection - causes

Answer 1

Strep pyogenes and staph aureus

Clinical patterns:
-Impetigo
-Ecthyma [form of impetigo - small punched out ulcers]
-Cellulitis
-Folliculitis

Question 2

Phytodermatitis

Answer 2

Plant allergen or allergen-induced by action of sunlight on plant product
Acute
Often vesicular
Linear lesions

Question 3

Cutaenous larva migrans

Answer 3

Caused by animal hookworm
Migratory, intensely pruritic
Can have follicular and bullous forms
Cross-reaction with strongyloides serology

Treatment - ivermectin or albendazole

Question 4

Scabies - organism and transmission

Answer 4

Ectoparasite mite = sarcoptes scabiei var hominis

Symptoms due to hypersensitivity to mite, eggs or faeces

Transmission:
Skin to skin contact
Fomites and bedding
NO IMMUNITY

Question 5

Scabies - clinical features

Answer 5

Pruritus
Burrows
Papules/nodules/vesciles
Web spaces of hands
Excoriations
Soles of feet - more affected in infants

Question 6

Scabies - crusted scabies

Answer 6

Hyperkeratosis
Itch may not be a prominent features
Associated with HIV and HTLV-1

Question 7

Scabies - diagnosis

Answer 7

Clinical
Identification of mite [or eggs]
Dermatoscope - delta wing sign

Question 8

Scabies - treatment

Answer 8

Treat whole family/close contacts
Medications:
-Topical = 5% permethrin cream, benzyl benzoate or 0.5% malathion lotion
-Oral = ivermectin [CI = loa loa, pregnancy, children <15kg]

Question 9

Scabies - complications

Answer 9

Secondary bacterial infections
Post-streptococcal GN
Bullous disease
Erythroderma
Widespread skin loss - particularly immunosuppressed

Question 10

Scabes - Mass drug administration

Answer 10

Community prevalence of scabies >10%
2 doses of oral ivermectin
3-5 rounds of MDA
stop if prevalence <2%

Question 11

Dermatophytes - organisms

Answer 11

Fungi that digest keratin
Cause supreficial disease affecting hair, nails and skin

Anthropophilic = trichophyton spp
Zoophilic = microsporum spp
Geophilic = microsporum spp

Question 12

Dermatophytes - diagnostic tests

Answer 12

Clinical
Fluorescence [Wood’s lamp] = helpful for M canis [not all species fluoresce]
Culture = for diagnostic uncertainty/infection resistance

Question 13

Tinea pedis

Answer 13

Fine scaly plaques - on plantar foot, web spaces
Macerated skin

Question 14

Tinea manuum

Answer 14

Fine silver scale with accentuation in palmar creases
Can have active border

Question 15

Tinea capatis

Answer 15

Patchy non-scarring alopecia [can scar if long duration]
Short broken hairs
Fine scaly plaques
Kerion = inflammatory tinea - oedematous plaques with erythema and pus

Question 16

Tinea cruris

Answer 16

Genital - fine scaly plaque with active border

Question 17

Tinea faciei/barbae

Answer 17

Face/hair follicles = fine scaly plaque

Question 18

Tinea unguium/onchomycosis

Answer 18

Nail infection:
-Onycholysis
-Subungual debris
-Nail thickening

Question 19

Dermatophytes - treatment for tinea

Answer 19

Topical = clotrimazole 1% cream, terbinafine 1% cream

Oral = griseofulvin, itraconazole, fluconazole

Sytemics for extensive disease, involvement of hair and nails

Question 20

Candidiasis

Answer 20

Yeast infections
Occuring in moist areas/body folds
Erythema/maceration +/- pustules

Treatment = Nystatin, clotrimazole, terbinafine 1%, fluconazole, itraconazoles

Question 21

Tinea versicolor

Answer 21

Yeast infeciton - Malassezia spp
Truncal rash - with hypo/hyperpigmented macules and patches

Treatment phase = azole cream/shampoo or oral antifungal

Prophylaxis phase = shampoo once weekly for 1 year

Pigment changes persist for 12 months