Fungal skin infections Flashcards
pathophysiology of dermatophye infections
- dermatophyte = unbrella term for Microsporum, Trichophyton and Epidermophyton
- survive on dead keratin and do not invade living tissue
- affect top layer of epidermis, hair, nails and skin
*mucosal layers not affected because lack a keratin layer
-also known as ringworm or tinea (fungus)
what are the goals of therapy for dermatophyte infection
Eradicate causative organism
Resolve lesion and symptoms
Prevent spread of infection
Prevent secondary complications (e.g., postinflammatory hyperpigmentation, scarring)
when to refer payents with a dermatophyte infection
- expericing tinea capitis, tinea barbae or tinea manuum: systemic therapy req bc topcal agents dont penetrate hair follicles or thick palmar skin
- experiencing infection with unclear etiology
- immuncompromised
- presoning poorly or intolerant to topical therapy
experiencing extensive, disabling, multifocal or inflammatory disease
non pharm therapy for dermatophyte infections
- keep skin clean: bathe daily, avoid excessive rubbig with towels, electric hair dryer on cool setting can be helpful, use warm compress (1 min on 1 min off) for 15-20 min TID
- wear loose fititng clothing of breathable moisture whicking fabic
- apply non medicated powders several times daily to reduce moisture in skin folds and rubbing (but no evidence for this)
*corn starc h could theoretically encourage fungal growth by acting as food source for yeast
- avoid dirrect/indirect contact w/ infected persons, dot share clothing with infected persons
monitoring dermatophyte infections
improvement in redness, scaling, itch and irritation may occur within 2–3 days of starting therapy, the full treatment course must be completed to prevent recurrence.
what is Pityriasis Versicolor
yeast infections
aka Tinea Versicolor
pathophysiolog of Pityriasis Versicolor
- infection of stratum corneum of skin where subaceous glands are present
- years involved are Malassezia species
- normally colonize skin but can cause an opportunistic infection
- affects ~3% of the general population and is primarily a cosmetic problem
- recurrence rates = 80%
goals of therapy for Pityriasis Versicolor
Eradicate or reduce yeast to re-establish normal balance of microbial flora
Reduce or eliminate skin lesions and symptoms
Prevent recurrences of infection
patient assessment of Pityriasis Versicolor
*etiology of the infection is unclear, patients require further assessment to confirm diagnosis
non pharm therapy for pityriasis versicolor
- same as dermatophyte
* also avoid applciation of oil to skin -> Malassezia species can convert to a pathogenic form in the presence of oil and hot, humid environments.
preventitive therapy for pityriasis versicolor
- high rate of recurrence (up to 80% within 2y after treatment)
- Prophylactic treatment with topical or oral therapy on an intermittent basis is often necessary, albeit based on limited evidence.
- preventative treatment with once -twice monthyl application of selenium sulfide suspenstion is often recommended to reduce recurrence but limited evidence
- medicated shampoos have also been used with zinc pyrithione, salicylic acid or sulfur
Cutaneous Candidiasis
yeast infection that develop in warm, moist environemnts such as intertrigo, ncreased skin pH, competing bacteria removed by antibiotic treatmens to glucose content in sweat increases
- > Candidal intertrigo is often colonized w/ bacteria
- > candidal paronchia: occurs in individuals who ahve hands in water frequently (painful swollen reddened nail folds, and lead to depressions og nail plate
goals of therapy of Cutaneous Candidiasis
eradicate or reduce yeast to re-establish normal balance of microbial flora
Eliminate or reduce lesions and symptoms
Prevent spread of infection
Prevent recurrences
assesment of cutaneous candidiasis
Patients with widespread, systemic or persistent, recurrent infection or those who are immunocompromised require further assessment and/or treatment by an appropriate health-care practitioner.
monitoring therapy of cutaneous candidiasis
- Substantial improvement should be evident within 1 week of topical treatment.
If topical corticosteroids are used (with antifungals) to control an inflammatory candidal intertrigo, patients should be monitored closely for the development of a hidden bacterial infection or striae.
what medications are effective for treatment of infections caused by dermatophytes or yeasts
Allylamines: Terbinafine (lamisil)
Azoles: Clotrimazole (canesten), Ketoconazole (ketoderm), Miconazole (micatin)
Hydroxypyridone: ciclopriox (loprox, stieprox)
* cause Irritation, erythema, itching, stinging some can cause hypersensitivity rxns
thiocarbamates for fungal ifnections
- can treat tinea corporis or cruris
- ineffective in treating cutanous candidiasis
selenium sulfide for fungal ifnections
can treat pityriasis versicolor and used for its prevention
undecylenic acid for fungal infections
- can treat tinea corporis and cruris
- ineffective in treatment of cutaneous candidiasis
what topical antifungals are safe during pregnancy
- clotrimazole, miconazole (first line), nystatin
limited data likely safe if use in small area: ciclopirox, selenium sulfide, tolnaftate
what topical antifungals do not have human evidence for use in pregnancy
Zinc pyrithione and Undecylenic
what anifungals are safe for breastfeeding
- clotrimazole, ketoconazole, miconazole, nystatin
no humand ata but low risk “Selenium sulfide(most unliekly to psoe risk), terbinafine, tolnaftate, undecyclenic acid
Intea barbae
- in coarse hair of beard area, ocassionally mustache
- unlilateral lesions, sppear as scaly patches or reddened areas with perifollulcular papules, pustules or swollen inflamed purulent mass and hair
- risk: adult males or hirsute women, farm workers, direct/indiect contact w/ ifnected person, mosit condiiotns, impaired immune states, genetic predisposition
Tinea capitis
- scalp hair follucles adjacent to skin
- “black dot tinea capitis” most common, annular patch of itchy scaling skin and hiar loss, hairs can break off
“Gray patch intea capitis” contraccted from cats and dogs causes loss of hair sheath in affected area. hair turns grey breaks 1-2 mm above scalp
risk factors: primarily affects children, african american/hispanic children, low socioeconomic crowded env, direct/indirect contact, mosit condiitons, impaired immunity
Tinea corporis
- usually smooth and hairless areas fo trunk//limbs (excluding face, ahnds, feet and groin)
- typicall round, erythateous or hyperpigmented lesions, scal with a clearing central portion and riased vesicular border that advances circumferentially outwards
risk factors; atheltes in sports w/ skin-to-skin contact, direct/indirect contact w/ infected persons, mosit conditions, impaired immunity, genetic predisposiiton
Tinea cruris
- symmetrical involing groin area (medial and upper parts of thigh and pubic area)
- occasionally the anal cleft is affected
- unlikelt yeast infections, crotum and penis are usually spared
- annular erthematous or hyperpigmented patch with scales and central celaring
- puriritus is common
risk factors: males, individuals with infection on feet which is spread to groin while putting on underwear, direct or indrect contact w/ ifnected person, moist conditons invluding occlusive cltohing, humid climates, impaired immunity, genetic predisposiiton
Tinea manuum
- palmar surface of hand more often than the back of hand
- lesions:
- > palmar: diffuse dryness and hyperkeratosis
- > dorsal: usually dry, mild diffuse scales on erythmatous or hyperpigmented base
risk: if ahve intea peditis, direct/infect contact, mosit, impaired immune, genetic predis
Pityriasis versicolor
- found on back, chest, upper arms
- commonyl asymptomatic
multiple white-reddish brown macules that may coalesce to form alrge patches of varous colours ranging form white to tan
- fine scale is apparent when scracthed
risk facotrs: postpubertial chidlrena nd young adults, warm, humid climates, genetic predispostion, immunodeficiency, malnutrition, oily skin, oral contraceptive use
not due to poor hygiene and not considered contagious
cutaneous candidiasis
- occurs in moist areas, any skinfold such as gluteal fold, axillae, interdigital spaces, area under breasts or adbominal folds
- beef red, edematous macerated patches with irregula scalloped borders
- papules and pustules form outside the borders
- pruritis and soreness are common
risk factors: diabetes mellitus, malignancy, obesity, neutropenia, HIV, infection, psoriasis, contact dermatitis, corticosteroid use, antiobioics, tropical env
not considered contagous
