cutaneous fungal infections Flashcards
What is Tinea versicolor also known as?
- Pityriasis versicolor
What is Tinea versicolor?
- common superficial skin infection that may become chronic
- superficial yeast infection caused by Pityrosporum ovale aka Malassezia furor
- Malassezia is normally found on human skin (overgrowth)
- organism oxidizes fatty acids in the skin and inhibits tyrosinase in the melanocytes leading to loss of pigmentation
Pathogenesis of Malassezia?
transformation of Malassezia from yeast cells to a pathogenic mycelial form is assoc with the development of clinical disease
- not related to poor hygiene
Who commonly gets Tinea versicolor and what are the risk factors?
- very common,
- mostly common in teens (>15), and young adults, athletes
- RFs: heat, humidity, excessive sweating, use of topical skin oils, HIV infection
How is Tinea versicolor characterized?
- by hypo pigmented lesions on the trunk that are asymptomatic
- sometimes can be pruritic
- velvety tan, pink or white macules
- hypo pigmented areas that don’t tan with rest of the skin
- 4-5 mm or confluent
- Trunk, upper arms, neck and groin
- lesions may scale if scraped (looks like dry skin)
Lab findings of tinea versicolor?
- skin scrapings seen on KOH prep show budding spores and large hyphae “spaghetti and meatballs” (KOH kills epithelial cells)
- fungal culture not helpful
- DDX: vitiligo, seborrheic dermatitis (seen in HIV), pityriasis alba
Tx of Tinea versicolor?
DOC: Selenium sulfide lotion or shampoo 2.5% (Rx)
- apply once daily
- apply with a cotton ball, allow to dry 15 min prior to bathing
- once daily for 7 days
- to prevent recurrence maintenance therapy 2x a month (have chronic recurring condition)
- other txs:
tablets: Fluconazole (Diflucan) -> 300 mg tablets or Intraconazole (sporanox) tablets 200 mg
or Ketoconazole shampoo
Maintenance therapy for Tinea versicolor?
- up to 80% of cases will have recurrence in subsequent 2 years w/o maintenance therapy
- Selenium sulfide lotion or shampoo 2x monthly
- pt education: may take months for hypopigmented areas to normal (they may not ever)
3 species of fungi that cause human infection? (dermatophytes)
- Trichophyton
- Microsporum
- Epidermophyton
localized sxs of dermatophytes do to the fact that they grow in skin, hair and nails?
- digest keratin
so see scaling, nails thicken, and crumble and will see hair loss
Risk factors for Tinea?
- warm, moist, occluded environments, family hx, compromised immune system, alteration in normal flora
- spread by contact: humans, animals, inanimate objects
Where are Tinea infections located in the epidermis?
- in the stratum corneum (superficial 1/2) and are caused by a variety of fungal species
- caused by dermatophytes:
Trichophyton rubrum
Trichophyton tonsurans
Trichophyton mentagrophytes
Microsporum canis
Epidermophyton floccosum
Classification of Tinea?
- Tinea corporis: body “ring worm”
- Tinea cruris: groin “jock itch”
- Tinea pedis: feet “athlete’s foot”
- Tinea capitis: scalp
- Tinea unguium: nails
sxs of a Tinea infection?
- generally include localized pruritus, burning and stinging
- if inflammatory reaction may have erythema and vesicles in addition to sxs listed above
Dx of Tinea infection?
- microscopic eval: skin margin scraping and KOH prep
- fungal culture: takes 2 weeks (do when it is recurrent infection)
- Wood’s lamp: will ID microsporum species
Tinea Corporis?
- Face, limbs, and trunk
ring shaped lesion with well demarcated margins - central clearing
- scaly, erythematous border
- transmitted by contact by humans, animals, sports equipment
-tx: topical azole antifungal (apply 1-2 x daily for 2-4 weeks) continue for a week after lesions clear
Tinea cruris?
- groin, inguinal folds, spares the scrotum
- borders distinct
- lesions are large, erythematous, macular with central clearing
- hallmark: pruritus with burning
Tx: topical azole antifungal
(Better to use powder, already a moist area)
Tinea pedis?
interdigital: scaling, maceration, fissures b/t toes
plantar: diffuse scaling of soles
acute vesicular: vesicles and bull on the sole of foot, great toe and instep
tx: topical azole antifungal (dry spray, allow feet to be exposed to air)
Tinea capitis?
- most cases in children
- inflamed scaly, alopecic patches
- diffuse scaling with round alopecic patches due to broken hair shafts
- tender, pustular nodules
- tx: griseofulvin for 8 weeks, or terbinafine for up to 4 weeks (cannot use topical therapy: must be systemic therapy)
Tinea unguium
- also known as onychomycosis
- typically toenails but can affect fingernails as well
- oncholysis may occur
- infection usually moves distal to proximal
- usually asymptomatic
- tx with oral terbinafine (lamisal) 250 mg qday x 6 wks for fingernails and 12 weeks for toenails (have to have systemic tx)
(monitor LFTs, and CBC)
alt: itraconazole (sporanox)
- are a variety of topical Rx meds that are available but they have limited efficacy (50%)
- systemic antifungals are very toxic and there are a lot of drug interactions -> just let go fungal infections in elderly sometimes
Cutaneous candidiasis?
intertrigo: axillae, under breasts, groin, intergluteal folds
balantitis: glans penis
candidal folliculitis: follicular pustules
candidal paronychia: nail folds
Thrush: mouth and tongue
diaper dermatitis
** will be more inflamed and red compared to Tinea (this will be in a round pattern)
RFs for candidiasis?
- infection
- recent abx therapy
- diabetes
- systemic and topical steroids
- immunosupression
- warm, moist conditions
- break in the skin
Tx of candidiasis?
- Thrush: oral lozenge or swish and swallow -> nystatin, and clotrimazole
cutaneous:
powder for macerated areas (Nystatin)
topical clotrimazole (lotrimin), ketoconazole
-if failure of topical therapy: oral fluconazole (Diflucan)
