Fungal Skin Infections Flashcards
What are the 3 most common types of fungal skin infections?
1) Dermatophyte Infections
2) Yeast: Pityriasis Versicolor
3) Yeast: Cutaneous Candidasis
How do dermatophytes cause infection and how are they transmitted?
Live on dead keratin cells and do not invade living tissues thereby only affecting the top layer of the epidermis, hair, nails and skin
Infections are transmitted through direct contact with infected persons, soil or animals
Commonly called ringworm or tinea
What are the goals of therapy for dermatophyte infections? (4)
1) eradicate causative organism
2) resolve lesion and symptoms
3) prevent spread
4) prevent secondary complications
What are some of the common characteristics for infections caused by dermatophytes?
- usually unilateral lesions; scaly patches or reddened areas
- itchy, scaling skin and hair loss
- round erythematous or hyper-pigmented patches
Who needs further assessment when presenting with a dermatophyte infection?
- infection with unclear etiology
- immunocompromised patients
- responding poorly to or are intolerant of topical therapy
- experiencing extensive, disabling, multifocal or inflammatory disease
What are the non-pharm options for a dermatophyte infection?
- keep skin clean and dry to discourage proliferation
- cool water compresses 1 min on, 1 min off for 15-20 minutes 3x day to dry skin through evaporation
- wear lose fitting clothing to allow adequate ventilation
- NOT ENOUGH EVIDENCE –> non-medicated powders applied several times per day to reduce moisture in skin folds
What are the topical pharmacological therapies available for dermaophyte infections? (7) Which of these is the shortest duration of treatment and which are safe in pregnancy?
- ciclopirox (no human data, low risk to mother and child)
- clotrimazole (considered safe)
- ketoconazole (no human data in pregnancy, safe in breastfeeding)
- miconazole (FIRST LINE safe)
- terbinafine –> SHORTEST duration of treatment (limited evidence, risk considered low)
- tolnaftate (limited evidence but risk considered low in pregnancy)
- undecylenic acid –> effective but not enough evidence for pharmacotherapeutic comparison (not preferred in pregancy)
What is an INAPPROPRIATE recommendation for the treatment of dermatophyte infections?
Nystatin
What is an important counselling point when recommending a treatment for a dermatophyte infection?
Even though there is improvement in redness, scaling, itch and irritation within 2-3 days of starting therapy, full treatment course must be completed to prevent recurrence
What is the optimal dosage regimen for treatment of fungal infections?
Not determined due to lack of quality evidence
Usually for a minimum of 2 weeks or until 1 week after the skin clears
Terbinafine treatment is recommended to be applied QD for 1 week
How do yeast infections of tinea versicolor cause s/s?
Infects the stratum corneum where sebaceous glands are present; primarily a cosmetic problem where the lesions may not tan or darken on exposure to sunlight in the same manner as surrounding skin
What are the common characteristics of the yeast infection: tinea versicolour?
- commonly asymptomatic
- multiple white to reddish-brown macules that may coalesce to form large patches of various colours
- fine scale is apparent when scratched
- not due to poor hygiene
NOT CONSIDERED CONTAGIOUS
What are the nonpharmacologic therapies for yeast infections: tinea versicolor?
- avoid application of oil to the skin; could cause conversion of species to pathogenic form
- keep skin clean and dry to discourage fungal proliferation
- wear lose fitting clothing
What are the topical pharmacologic therapies used for a tinea versicolor infection?
1) Ketoconazole, 65% cure rate, most extensively studied (oral not recommended due to hepatotoxicity)
2) Terbinafine, 45% cure rate, less studied (oral is ineffective)
3) Clotrimazole, miconazole, ciclopirox have equivalent efficacy
Oral products are fluconazole and itraconazole; used when people are intolerant or unable to use topical therapies
What is the preventitive pharmacoogical therapy for tinea versicolor?
High rate of recurrence suggests prophylactic treatment with topical or oral therapy on an intermittent basis is often necessary
1-2x month applications of selenium sulfide suspension is often recommended, evidence is lacking
Itraconazole 200mg 1x/month has been used successfully
How long might it take for the resolution of scaling with pityrasis versicolor with treatment? What about pigmentary changes?
Scaling –> promptly
Pigmentary changes –> may take weeks to months to resolve
How does cutaneous candidasis cause s/s and where is it most common?
Develop in warm, moist conditions where skin pH is increased and competing bacteria are removed by antibiotic treatments or when glucose in sweat increases
Occurs often in individuals who often have their hands in water
What are some of the characteristics of the presentation of cutaneous candidasis?
- painful reddened and swollen nail folds
- often colonized along with bacteria; may cause secondary infection
- beefy red edematous macerated patches with irregular scalloped boarders
- papules and pustules can form outside of borders
- pruritus and soreness are common
When would you have to refer someone presenting with cutaneuous candidasis?
patients with widespread, systemic or persistent, recurrent infection
those who are immunocompromised
What are the pharmacologic therapies for cutaneous candidasis?
Many topical agents are effective: azole antifungals like clotrimazole, ketoconazole, miconazole, and others like ciclopirox, nystatin and terbinafine are all considered safe and effective.
Most evidence is for:
- clotrimazole
- nystatin
- miconazole
If there is inflammation, low to mid potency TCS can be used sparingly 1-2x day for 1-2 weeks in conjunction with an antifungal
When should improvement of s/s be seen when treating cutaneous candidasis?
Substantial improvement within 1 week
Persistent infection may be a sign of immunosuppression and patients should be investigated further
What is the only NHP that has shown some benefit in the treatment of fungal skin infections?
Tea tree oil
