Skin Infections & Rashes Flashcards
What factors are important?
- Overall appearance of skin
- Rash distribution/location
- Rash pattern
- Local organization of lesion
- Lesion morphology (shape, size, warmth, tenderness, blanching)
Macule
flat, less than 1cm
Papule
elevated, less than 1cm
Plaque
elevated, flat top, more than 1cm
Nodule
domed/rounded, more than 1cm
Pustule
discrete, pus-filled lesion
Vesicle
elevated, less than 1cm, serous fluid
Bulla
elevated, greater than 1cm, serous fluid
Petechiae
purpuric macules, up to 2mm, don’t blanch
Palpable purpura
elevated, firm, hemorrhagic papules or plaques
Maculopapular
Combination of macules and papules
Morbilliform
measles-like
scarlatiniform
resembling scarlet fever; sandpaper appearance
Which diagnostic studies are relevant for rashes?
- Culture
- Histopathology
- Serology
What skin abnormalities are associated with primary bacterial infection?
Cellulitis, furuncles, skin lesions
What mechanisms are involved in the pathogenesis of bacterial infections?
- local replication/local inflammation
- circulating exotoxins (SSSS)
- immunologic mechanisms
- manifestation of DIC (disseminated intravascular coagulation)
What does cellulitis look like?
- Area of edema, warmth, redness
- Infection of SQ tissue and dermis
- Swollen LN, fever, chills, malaise possible
- Pathogens: Staph. aureus, Strep. pyogenes
What pathogens should be considered?
Both mouth and skin flora
Common pathogens: pasteurella, anaerobes, Staph. aureus, GAS
Often polymicrobial
What pathogens cause periorbital cellulitis?
Sinus and skin flora
Common: Strep. pneumoniae, H. influenzae, M. catarrhalis, S. aureus
RULE OUT ORBITAL CELLULITIS
erysipelas
Superficial form of cellulitis with LN involvement
Pathogen: Strep. pyogenes (GAS)
necrotizing fasciitis
- progressive, rapidly spreading infection of deep fascia
- secondary necrosis of SQ tissues
- Strep. pyogenes, other bacteria
- Rx: surgical debridement
furuncle
boil, most commonly caused by Staph. aureus
impetigo
honey-crust scabs on baby’s face caused by GAS or Staph. aureus
bullous impetigo
flaccid bullae caused by staph. aureus
