Fungi and infestations Flashcards
What are dermatophyte infections?
invade and multiply in stratified squamous epithelium.
Microsporum, trichophyton (most common) and epidermophyton
Human to human, animal to human, soil to human
Ring worm, tinea
What is tinea curis?
Involves groin region, M>W
T. rubrum
Well demarcated pruritic erythematous plaque on the inner aspect of one or both thighs and can extend to the pubic, suprapubic, perianal and buttock regions.
What is tinnea manuum?
asymmetrical involvement with scaling, much more prominent in one hand than the other
What is tinea pedis?
Athletes foot
white maceration between the toe webs
With more widespread bilateral involvement, this is sometimes referred to as moccasin feet.
What is onychomycosis?
Distal white discolouration, loss of nail plate, onycholysis with the nail lifting up from its bed and hyperkeratosis. This may be mistaken for psoriasis
What is tinea capitis?
Microsporum and Trichophyton. Children are particularly prone
Patchy hair loss with varying degrees of scale, erythema and pustules. Infected hairs tend to break at the base, leaving stubble.
Occasionally, there is invasion of the visible epidermis, which leads to a very pronounced inflammatory response, resulting in a boggy, painful swelling with associated alopecia and regional lymphadenopathy. This is known as a kerion.
What are the investigations used for fungal infections?
Skin scrapings
Nail clippings including the sub-ungual debris
Hair samples
Certain fungi fluoresce under UV light examination known as a Wood’s light.
How are fungal infections treated?
Topical anti-fungal agents such as one of the Azoles (Miconazole) or topical Terbinafine
systemic agent such as Terbinafine (measure liver function, 2-4 weeks skin, 3 months finger nail, 4 months+ toe nail Itraconazole (nail, scalp, hair)
Griseofulvin is licensed for use in children (not effective, tinnea <12 yrs, may induce photosensitive rash)
Ketoconazole (topical and shampoo, can lead to gynaecomastia)
How is candidiasis managed?
polyenes such as Nystatin or Amphotericin B if it is a systemic infection.
Topical Azoles: Clotrimazole or oral Fluconazole.
What is pityriasis versicolor?
development of finely scaling yellowish or brown macules, most commonly seen on the trunk
Hypopigmented or hyperpigmented depending on the racial skin type.
Mild scaling
People return from a holiday abroad with hypopigmentation at the site of the lesions.
Relapse is common
topical agent: Miconazole. Older treatments include Selenium sulphide shampoo which is applied overnight and washed off on three consecutive days.
Extensive disease Itraconazole daily for a week
What is seborrhoeic dermatitis?
Face, scalp (young children cradle cap) (adults dandruff), Flexures Topical azoles Low potency steroid for rapid treatment Recurrence is common Tacrolimus and Pimecrolimus
How does scabies present?
itchy spots which become excoriated with time.
sites involved are finger webs, flexures, axillae, breasts in women, ankles and insteps
Crusted scabies, high mite load
Treatment: Permethrin or Malathion. This should be left applied to the skin for at least twelve hours (overnight). Repeated 7 days after
Itching may persist after and lead to eczema
