ID Derm Part 2 Flashcards
What are the three groups of cutaneous fungi that can cause superficial infections?
Dermatophytes
Malassezia Spp.
Candida Spp.
**superficial cutaneous and limited to the epidermis
What tissues do dermatophytes infect?
keratinized tissues
stratum corneum
nail or hair
tinea capitis
dermatophytosis of the scalp and associated hair
most cases caused by Trichophyton tonsurans
most common worldwide is Microsporum canis
multiple patchy alopecic areas of different sizes and shapes - hair shafts are broken off near scal surface
kerion
painful inflammatory booggy mass with broken hair follicles
may discharge pus
higher risk of carring
treatment for tinea capitis
systemic treatment
griseofulvin
terbinafine
tinea pedis (athlete’s foot)
may have fine scales on the soles and between toes
vesicles often appear on bottom/sides of foot
interdigital caling and scaling on the bottom of the feet
interdigital type, moaccasin type, and vesiculobullous type
onychomycosis
potential complication of tinea pedis
chronic fungal infection of the nailbed
responds poorly to topical antifungals
tinea corporis
aka “ringworm”
annular lesions with central clearing is typical
centrifugal spread after 1-3 week incubation period
caused by:
- T. rubrum
- M. canis
- T. mentagrophytes
tinea facei
facial involvement excluding beard and musctache areas
scaling present in fewer than 2/3 of cases
tinea versicolor
not a dermatophytosis
caused by overgrowth of species of Malassezia
tends to recur annually in the summer months
characterized by variable colored often round patches, most commonly in the trunk
treatment of versicolor
2.5 selenium sulfide shampoo
topical antifungals dialy for 2 weeks
oral antifungals for recalcitrant disease
diaper candidiasis
satellite papules and pustules help differentiate this from other eruptions
rash does not improve with application of barrier creams
urease enzymes present in feces release ammonia from urine, which cause acute irritant effect and disrupt epidermal barrier
cutaneous candidiasis
C. albicans most common
part of normal flora of mucous membranes
treat with topical antifungals
candidal intertrigo
candidiasis of large skin folds
may arise in groin, armpits, between buttocks, under large pendulous breasts and overhanging abdominal folds
sporotrichosis
sporothrix schenickii
subcutaneous infection by fungus
grows in decaying vegetable matter
dermal nodule appears then a chain of secondary nodules on the course of the lymphatics
blastomycosis
chronic mycosis, most cases in Great Lakes region in US
skin lesions are common from dissemination in face and extremities
thick walled refractile spheres with broad based buds
superficial pyodermas
infections in the epidermis, just below the stratum corneum (impetigo) or the hair follicles (folliculitis)
S. aureus is the most common
Group B strep is a common cause in babies
bullous impetigo
bacterial infection caused by S. aureus
caused by secreted exotoxin - exfoliative toxins that cause blistering by binding to desmoglein-1
staphylococcal scalded skin syndrome
focus of infection secretes toxin into the blood
leads to widespread superfiical blisters
wound cultures from erosions are negative
What exotoxins cause staph scalded skin syndrome?
epidermolytic/exfoliative toxins A and B
bind to desmoglein-1
scarlet fever
caused by S. pyogenes
exotoxins SPE-A, B, C
produced by group A strep
delayed-type skin reactivity to strep products
beefy-red pharynx, tonsillitis, submandibular LAD
white strawberry tongue in first several days and red-strawberry tongue after 4-5 days
sandpaper erythema and circumoral pallor
pastia’s lines - linear petechia in antecubital axillary folds
cellulitis
infection of dermis that often begins with a wound or fungal infection
erythematous, tender plaque
more common in lower leg
80% caused by group A strep and S. aureus or ther infections
therapy for cellulitis
begin antibiotics immediately with coverage for gram positive bacteria
erysipelas
superficial cellulitis with marked dermal lymphatic involvement
main pathogen is group A strep
