FUNGAL SKIN INFECTIONS Flashcards
What is Tinea?
A superficial fungal infection of the skin caused by Dermatophytes
What are dermatophytes?
A fungus that infects keratinous tissue and are able to invade the hair, skin and nails of a living host
What is Tinea capitis?
A dermatophite fungal infection of the scalp
“Scalp ringworm”
What is Tinea corporis?
A dermatophite fungal infection of the trunk/legs/arms
“Ring worm”
What is Tinea pedis?
A dermatophite fungal infection of the feet
“Athlete’s foot”
Most common cause of Tinea capitis?
Trichophyton tonsurans
May also be caused by microsporum canis acquired from cats or dogs
Presentation of Tinea capitis?
Scaling and hair loss (scarring Alopecia mainly in children)
If untreated a raised, pustular, spongy/boggy mass called a Kerion may form
Diagnosis of Tinea capitis?
Scalp scrapings
Wood’s lamp - microsporum canis shows green fluorescence
Management of Tinea capitis?
Oral antifungal - terbinafine for Trichophyton tonsurans infections, griseofulvin for microsporum infections
Topical ketoconazole shampoo for the first 2 weeks to reduce transmission
What can cause Tinea corporis?
Trichophyton rubrum
Trichophyton verrucosum - from contact with cattle
How does Tinea corporis present?
As a well-defined annular, erythematous lesion with pustules and papules
Management of Tinea corporis?
Oral fluconazole
How does Tinea pedis present?
Itchy, peeling skin between the toes
What is onychomycosis?
A fungal nail infection
Is onychomycosis more likely to involve the toenails or fingernails?
Toenails
Causative organisms of onychomycosis?
Dermatophites in 90% - mainly Trichophyton rubrum
Yeasts e.g. candida - 10%
Non-dermatophite moulds
Risk factors for fungal nail infections?
Increasing age
diabetes mellitus
Psoriasis
Repeated nail trauma
Features of fungal nail infections?
‘Unsightly’ nails
Thickened, rough, opaque nails
Investigtaions for fungal nail infections?
Nail clippings and scrapings of the affected nail - microscopy&culture
Management of mild, limited fungal nail infections?
Do not require Tx of asymptomatic
If dermatophyte or candida infection is confirmed…
If limited involvement - topical amorolfine 5% nail lacquer - 6 months for fingernails or 9-12 for toenails
Management of extensive nail infection with dermatophytes?
Oral terbinafine 6 weeks-3 months for fingernails, or 3-6 months for toenails
Management of extensive nail infection with candida?
Oral itraconazole
‘Pulsed’ weekly therapy
What causes seborrheoic dermatitis?
Chronic dermatitis caused by an inflammatory reaction to a proliferation of Malassezia furfur
Features of seborrheoic dermatitis?
Eczematous lesions on sebum-rich areas: scalp, periorbital, auricular, nasolabial folds
Otitis external and blepharitis may develop
What disorders is seborrheoic keratosis associated with?
HIV
Parkinson’s disease
Management of scalp seborrheoic dermatitis?
Ketoconazple 2% shampoo
OTC preparations containing zinc pyrithione (‘Head&Shoulders’) and tar (Neutrogena T/Gel) can be used
Selenium sulphide and topical corticosteroids may also be useful
What is Pityriasis versicolor?
A superficial cutaneous fungal infection caused by malassezia furfur
Most commonly affects the trunk and causes hypopigmented/brown/pink patches with some scale and mild pruritus
Often more noticeable following a suntan
Predisposing factors for pityriasis versicolor?
occurs in healthy individuals
immunosuppression
malnutrition
Cushing’s
Management of pityriasis versicolor?
Topical antifungal - ketoconazole shampoos is most cost effective for large areas
What is jock itch?
Tinea cruris
Tinea fungal infection in the groin, inner thighs and gluteal cleft
What is Tinea incognito?
A fungal skin infection where the clinical appearance has been altered by inappropriate treatment, usually a topical steroid cream
The more steroid applied, the more extensive the fungal infection becomes, and the less recognisable
This is why you should never give topical steroids if considering a fungal infection
