Skin infection

Question 1

What type of organism most commonly cause skin infections?

Answer 1

Gram positive cocci

Such as Staph. aureus and Strep. pyogenes

Question 2

What is cellulitis?

Answer 2

A spreading infection involving the deep subcutaneous layer

Question 3

Where does cellulitis occur?

Answer 3

Lower limbs, usually

Question 4

Risk factors for cellulitis?

Answer 4

Lymphoedema

Having an accessible site of entry for the bacteria:

• leg ulcer
• trauma
• tinea pedis (athlete’s foot)
• venous insufficiency
• leg oedema
• obesity

Question 5

What is tinea pedis?

Answer 5

Athlete’s foot

Question 6

Clinical features of cellulitis?

Answer 6

Erythema of area
Poorly demarcated margins
Swelling
Warmth
Tenderness

A low grade fever

Question 7

What is erysipelas?

Answer 7

Similar to cellulitis but it affects more superficial layers

It is mostly seen on the face

Question 8

What bacteria mostly causes erysipelas?

Answer 8

Group A
Beta haemolytic
Streptococci

Question 9

Clinical features of erysipelas?

Answer 9

Raised skin, erythematous

Margin is sharply demarcated from normal surrounding skin

Question 10

Diagnosis of cellulitis?

Answer 10

Clinical
Ask about risk factors
No point doing bloods etc.

Question 11

Management of cellulitis?

Answer 11

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

Question 12

What is necrotising fasciitis?

Answer 12

A deep seated infection of the subcutaneous tissue

Results in a severe spreading infection that destroys fascia and fat

Initially it spares the skin

Question 13

Which has a higher mortality: cellulitis or necrotising fasciitis?

Answer 13

Necrotising fasciitis

Has a high mortality

Question 14

Clinical features of necrotising fasciitis?

Answer 14

Spreading erythema
Crepitation when you put pressure on skin

Systemic toxicity
Severe pain at infection site

Question 15

Two types of necrotising fasciitis?

Answer 15

Type 1: occurs in people who’ve had recent surgery and diabetics

Type 2: occurs in previously healthy people

Question 16

What organisms commonly cause type 1 necrotising fasciitis?

Answer 16

Usually a mixture or aerobes and anaerobes

Question 17

What organisms commonly cause type 2 necrotising fasciitis?

Answer 17

Group A streptococci

Question 18

What is the treatment of necrotising fasciitis?

Answer 18

Urgent surgical debridement!

Followed by aggressive broad spectrum antibiotics
- benzylpenicillin + clindamycin

Question 19

What is gas gangrene?

Answer 19

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

Question 20

Treatment of gas gangrene?

Answer 20

Urgent surgical debridement

Broad spectrum antibiotics IV

Question 21

What are dermatophytes?

Answer 21

Fungus that cause infection of the outer layers of skin, hair and nails

Question 22

What are ‘tinea’?

Answer 22

Ringworm! A type of fungus, not a worm!

Question 23

Where can tinea infect?

Answer 23

Tinea pedis: athletes foot
Tinea cruris: groin
Tinea corporis: whole body
Tinea faciei: face
Tinea manuum: hands
Tinea capitis: scalp
Tinea unguium: nails

Question 24

How is ringworm spread?

Answer 24

Direct skin contact

Indirect: through water, towels

Question 25

Diagnosis of ringworm?

Answer 25

Take a scraping from the lesion and analyse

Question 26

Treatment of ringworm?

Answer 26

Topical anti-fungals

Oral if more widespread

Question 27

What type of microbe is candida albicans?

Answer 27

Yeast

Question 28

Where does candida albicans infect?

Answer 28

Warm, moist regions of skin: groin, interdigital clefts

Also mucosal surfaces: mouth, genital tract