Cutaneous Fungal Infection

Question 1

cutaneous fungal infections affect…

Answer 1

epidermis only

Question 2

three groups of cute fungi

Answer 2

dermatophytes, malassezia, candida

Question 3

dermatophytes infect which tissues

Answer 3

keratinized- stratum corneum, nail, hair

Question 4

cause of tinea pedis

Answer 4

trichophyton rubrum - athletes foot

Question 5

3 patterns of tinea pedis infection

Answer 5

interdigital- scaling and redness b/w toes maybe w/ maceration (white scale from moist skin)

moccasin-lateral borders of feet, heels, soles; maybe vesicles and erytema at margins or onychomycosis (nail fungal infection)
-maybe hand invovement

vesiculobullous type- grouped vesicles or bullae on arch or instep, can be itchy or painful
-delayed hypersensitivity immune response to dermatophyte

Question 6

dx of tinea pedis

Answer 6

KOH testing under microscope

Question 7

tx for tinea pedis

Answer 7

topical antifungals until resolution, then continue for at least 2 weeks

Question 8

3 topical antifungals

Answer 8

imidazole- fungistatic

allylamines- fungicidal

ciclopirox- cidal and static

Question 9

complications of tinea pedis

Answer 9

lower leg cellulitis- risk factor is immunocompromise

tinea corporis

Question 10

onychomycosis and tx

Answer 10

fungal infection of nailbed

poor response to topicals, use oral terbinafine or azoles for 3 months (need to avoid w/ liver problems)

Question 11

tinea corporis is..

Answer 11

ringworm

dermatophytosis of skin usually trunk and limbs, w/ itching and asymmetric distribution

Question 12

dx of tinea corporis

Answer 12

KOH scrapings from red scaly margin- active border w/ central clearing

Question 13

why scrape before steroids?

Answer 13

might be fungal (tinea) rather than inflammatory- could result in tinia incognito and further spread

Question 14

tx of tinea corporis

Answer 14

topical tx like tinea pedis

oral terbinafine or fluconazole for severe/widespread cases

only need 1-2 weeks when only body or skin

Question 15

tinea capitis

Answer 15

dermatophytosis of scalp and hair, common in AA children

Question 16

spread of tinea capitis

Answer 16

direct contact w/ animals, humans, fomites

most common cause is microsporum canis (from animals)

most common in US is trichophyton tonsurans (human to human)

Question 17

pres of tinea capitis

Answer 17

non inflammatory- black dot (hairs coming out but breaking off at surface), seborrheic

inflammatory- kerion

broken hair, lymphadenopathy in nearby nodes

typically 4-8 yrs

Question 18

kerion

Answer 18

inflammatory tinia capitis- painful boggy mass w/ broken follicles, can result from untreated tinia capitis

often secondary bacterial infections

risk of scarring

Question 19

tx of tinea capits

Answer 19

topicals ineffective

griseofulvin is first choice in US

terbinafine has shorter tx course but more hepatotoxicity

Question 20

involvement of skin folds indicates..

Answer 20

less likely contact dermatitis, more likely infectious

Question 21

pres of diaper candidiasis

Answer 21

beefy red erosions and margional scaling

satellite papules and pustules

suspect w/ no improvement from zinc oxide pastes

Question 22

pathogenesis of diaper candidiasis

Answer 22

wet/dirty diapers not changed regularly- urease enzymes in feces

disruption of epidermal barrier allows candida entry

Question 23

tx of diaper candidiasis

Answer 23

nystatin or imidazole cream or ointment

hydrocortisone maybe w/ major inflammation, limited time

avoid high potency steroids, prevents effective dx testing, KOH can be negative

oral nystatin w/ thrush present, recurrence

Question 24

other causes of apparent diaper candidiasis

Answer 24

immunodeficiency, zinc deficiency

atopic dermatitis, psoriasis, irritant dermatitis (spares folds), tinea cruris

Question 25

irritant diaper dermatitis pres

Answer 25

erythema, erosion, spared folds, mainly convex areas

severe cases can show ulcerated papules w/ islands of re epithelizations

Question 26

tx of irreitant diaper dermatitis

Answer 26

barrier creams like zinc oxide paste

frequent diaper changes, looser fitting

address diarrhea, consider candidiasis

Question 27

candidal intertrigo- def, dx, pres

Answer 27

infection of large skin folds, warm moist areas

KOH exam show pseudohyphae

more burning than itching

Question 28

tx of candidal intertrigo

Answer 28

topical antifungals- nystatin, imidazoles

NOT allylamines

prevention: hygiene, dry, weight loss

systemic imidazoles for extensive

Question 29

examples of dermatophytes

Answer 29

trichophyton, microsporum, epidermophyton