Skin and Soft Tissue Infections Flashcards
What are the infections associated with the following depth of skin?
What are the causative organisms for impetigo, erysipelas, cellulitis and necrotising fascitis?
Impetigo - s. aureus (less commonly due to strep pyogenes)
Erysipelas - strep pyogens
Cellulitis - Strep pyogenes, staph aureus (uncommon), H. influenza (rare)
Necrotising fascitis (strep pyogenes or mixed bowel flora)
What are the signs of impetigo?
Superficial skin infection, multiple vascular lesions on an erythematous base
Golden crust is highly suggestive of this diagnosis
Which age group is impetigo common in?
Age 2-5 years of age
Where does impetigo normally occur?
Usually occurs on exposed parts of the body including face, extremities and scalp
What are predisposing factors for impetigo?
–Skin abrasions
–Minor trauma
–Burns
–Poor hygiene
–Insect bites
–Chickenpox
–Eczema
–Atopic dermatitis
What is the treatment for impetigo?
Small areas can be treated with topical antibiotics alone
Large areas need topical treatment and oral antibiotics (flucloxacillin)
Where does erysipelas affect?
Affects the upper dermis
What are the other features of erysipelas besides infeciton of the upper dermis?
Painful, red area (no central clearing)
Associated fever
Regional lymphadenopathy and lymphangitis
Typically has distinct elevated borders
Most commonly due to strep pyogenes
Where is erysipelas likely to occur?
Most cases involve the lower limbs (70-80%)
5-20% affect the face
- Tends to occur in areas of pre-existing lymphoedema, venous stasis, obesity, paraparesis, diabetes mellitus
- May involve intact skin
- High recurrence rate (30% within 3 years)
What layerof the skin does cellulitis affect?
It is a diffuse skin infection involving deep dermis and subcutaneous fat
How does cellulitis differ from erysipelas?
Cellulitis has no distinct elevated borders
What is the most likely causative organism for cellulitis?
Strep pyogenes and staph aureus
What are the symptoms that can occur in conjunction with cellulitis?
Fever
Regional lymphadenopthy and lymphangitis
Possible source of bacteraemia
What re the predisposing factors for cellulitis?
Diabetes mellitus
Tinea pedis
Lymphoedema
Patients can have lymphangitis and/or lymphadenitits
What is the treatment for erysipelas and celulitis?
- A combination of anti-staphylococcal and anti-streptococcal antibiotics
- In extensive disease, admission for intravenous antibiotics and rest
What are the hair assocaited infections?
- Folliculitis
- Furunculosis
- Carbuncles
What is the difference between folliculitis, furuncles and carbuncles?
Folliculitis - erythema and a psutule in a single follicle
Furuncle - red tender nodule surrounding a follicle with one draining point
Carbuncle - abscess of several follciels with several drainage points
Describe the appearance of folliculitis
Small red papules
Central area of purulence that may rupture and drain
Up to 5 mm in diameter
What is the most common organism for folliculitis?
Staph aureus
It is a benign condition, constitutional symptoms not often seen
What tissue layer does furunculosis spread into?
Extends into the dermis and subcutaneous tissue
Where does furunculosis usualy affect?
•Usually affected moist, hairy, friction-prone areas of body (face, axilla, neck, buttocks)
What is the most common organism that can cause furunculosis?
Staph aureus is the most common organism
What are the risk factors for furunculosis?
–Obesity
–Diabetes mellitus
–Atopic dermatitis
–Chronic kidney disease
–Corticosteroid use
How are carbuncles formed?
When infection extends to involve multiple furuncles
Where are carbuncles found?
•Often located back of neck, posterior trunk or thigh
Describe the abscess found in a carbuncle
Multi-septated abscess
What is the treatment of hair associated infections?
Folliculitis - no treatment or topical antibiotics
Furunculosis - no treatment or topical antibiotics, if not improving oral antibiotics might be necessary
Carbuncles often require admission to hospital, surgery and intravenous antibiotics.