Skin Infections Flashcards
erythema ill-defined on right leg on the tibial aspect
cellulitis
affects subcutaneous layer of the dermis
Group A ß - hemolytic streptococcus (Strep)
or Staph
Other if immunocompromised = Gram -ve rods, fungal
find site of entry (e.g. gardening, cut leg, shaving leg)
check webs of feet (e.g. athletes foot)
Cellulitis Risk Factors
Diabetic
Alcohol
IVDU
eczema
malignancy
venous stasis
PVD
Systemic steroids
biologics
immunosuppressed
Ix for cellulitis
Skin swab = negative, except children H. Influenza
Bloods = often only slightly raised inflammatory markers
Blood cultures = negative
Cellulitis mx
Demarcation
Elevation
Dressings may be needed
Abx = flucloxacillin, benzylpenicillin
Cellulitis complications
Recurrent lymphedema
Group a strep = glomerulonephritis
Bacterial endocarditis = ?metallic valve
Lipodermatosclerosis = affects both legs (brown deposits on left leg)
Venous insufficiency
cellulitis?
unitlateral or bilateral?
acute or chronic?
Lipodermatosclerosis mechanism
Venous hypertension, fibrin and vascular cuffing, ischaemic fat necrosis → fibrosis, haemosiderin deposit in the skin
tx = venous system
cellulitis vs lipodermatosclerosis
What is this?
onset of minutes , colour, pain, haemorrhage, bullae, raised CK
NECROTISING FASCIITIS
flesh eating bacteria
emergency
ix = CK, XR (osteomyelitis)
tx = debridement, get surgeons involved
Unilateral
Erysipelas = unilateral
caused by strep pyogenes in upper subcutaneous fat
Cellulitis vs erysipelas
4 month history of rash
face only
scale
seborrhoea dermattits
M. Furfur
symmetrical, sebum areas, HIV if severe?
tx = azole antifungals, maintenance, steroids
impetigo
fast spread, honeycomb crusting appearance, face and hands, initially vesicular, no prodrome unlike with HSV
staph infection
tx = none, topical, systemic if widespread
blistering conditions
erythema multiform = target pattern
what is this?
cold sore = HSV
prodrome, site, recurrence
recurrence = skin immunosuppression (UV radiation), stress, fever, common cold, altered immune states, altered hormonal milieu (menstruation)
eczema herpeticum
hx of cold sores, medical emergency, well-punched out lesions all over face and may get around the body
get ophthalmology review as can get herpes keratitis
HSV tx
systemic = aciclovir (oral/IV), IV for eczema herpeticum
HSV and VZV
stored in dorsal root ganglion
shingles can affect trunk as well (reaction of VZV, prodrome)
what is this?
pityriasis versicolor
Malasezzia furfur
predisposing factors = high humidity, high rate of sebum production
clinical diagnosis
ringworm
ix = skin swab
tx = anti-staph topical or systemic, antibacterial wash, eradicate nasal carriage if recurrent
candidiasis thrush
direct microscopy = hyphae
fungal cultures
dermatopathology = PAS stains
scabies
transmission = close prolonged contact
incubation = 2 to 6 weeks
rash usually in flexor areas
tx = lyclear (permethrin), derbac (malathion), wash all bedding and clothes (>50 degrees), treat all close family members
