Skin infection Flashcards
What type of organism most commonly cause skin infections?
Gram positive cocci
Such as Staph. aureus and Strep. pyogenes
What is cellulitis?
A spreading infection involving the deep subcutaneous layer
Where does cellulitis occur?
Lower limbs, usually
Risk factors for cellulitis?
Lymphoedema
Having an accessible site of entry for the bacteria:
- leg ulcer
- trauma
- tinea pedis (athlete’s foot)
- venous insufficiency
- leg oedema
- obesity
What is tinea pedis?
Athlete’s foot
Clinical features of cellulitis?
Erythema of area Poorly demarcated margins Swelling Warmth Tenderness
A low grade fever
What is erysipelas?
Similar to cellulitis but it affects more superficial layers
It is mostly seen on the face
What bacteria mostly causes erysipelas?
Group A
Beta haemolytic
Streptococci
Clinical features of erysipelas?
Raised skin, erythematous
Margin is sharply demarcated from normal surrounding skin
Diagnosis of cellulitis?
Clinical
Ask about risk factors
No point doing bloods etc.
Management of cellulitis?
Phenoxymethylpenicillin
PLUS
Flucloxacillin
Given IV followed by 2 weeks oral if infection is widespread
Give prophylaxis if recurrent
Try to reduce patient’s risk factors to prevent recurrence
What is necrotising fasciitis?
A deep seated infection of the subcutaneous tissue
Results in a severe spreading infection that destroys fascia and fat
Initially it spares the skin
Which has a higher mortality: cellulitis or necrotising fasciitis?
Necrotising fasciitis
Has a high mortality
Clinical features of necrotising fasciitis?
Spreading erythema
Crepitation when you put pressure on skin
Systemic toxicity
Severe pain at infection site
Two types of necrotising fasciitis?
Type 1: occurs in people who’ve had recent surgery and diabetics
Type 2: occurs in previously healthy people
What organisms commonly cause type 1 necrotising fasciitis?
Usually a mixture or aerobes and anaerobes
What organisms commonly cause type 2 necrotising fasciitis?
Group A streptococci
What is the treatment of necrotising fasciitis?
Urgent surgical debridement!
Followed by aggressive broad spectrum antibiotics
- benzylpenicillin + clindamycin
What is gas gangrene?
Infection of the deep tissues with Clostridium species
The toxins released by the bacteria cause muscle necrosis with severe pain, tissue swelling, gas production, sepsis
Very severe
Treatment of gas gangrene?
Urgent surgical debridement
Broad spectrum antibiotics IV
What are dermatophytes?
Fungus that cause infection of the outer layers of skin, hair and nails
What are ‘tinea’?
Ringworm! A type of fungus, not a worm!
Where can tinea infect?
Tinea pedis: athletes foot Tinea cruris: groin Tinea corporis: whole body Tinea faciei: face Tinea manuum: hands Tinea capitis: scalp Tinea unguium: nails
How is ringworm spread?
Direct skin contact
Indirect: through water, towels
