Bacterial Skin and Soft Tissue Infections

Question 1

What is the definition of cellulitis?

Answer 1

Cellulitis is an infection of the deep dermis and subcutaneous tissue

Question 2

What are the risk factors for cellulitis?

Answer 2

Diabetes
Venous insufficiency
Chronic oedema / lymphoedema
Eczema
Obesity
Toe web abnormalities

Question 3

What associated skin changes can occur in cellulitis?

Answer 3

Peu d/orange
Dermal necrosis
Blistering
Superficial bleeding

Question 4

What constitutional symptoms can occur in cellulitis?

Answer 4

Fever
Malaise
Lymphadenopathy / lymphangitis
Hypotension / tachycardia

Question 5

When is a skin swab required in the investigation of cellulitis?

Answer 5

When an atypical organism is suspected

Question 6

When should a patient with cellulitis be admitted to hospital?

Answer 6

They are elderly
They are immunosuppressed
They have significant co-morbidites
They have systemic symptoms
There is suspicion of atypical organism

Question 7

What are the potential complications of cellulitis?

Answer 7

Sepsis

Chronic oedema

Question 8

What is the management of cellulitis?

Answer 8

Empirical antibiotics (fluxcloxacillin, vancomycin)
Supportive care - analgesia, VTE prophylaxis, fluid management, wound care

Question 9

What are the risk factors for necrotising fascitis?

Answer 9

Recent surgery
Cutaneous trauma
Hospitalisation
IVDU
Immunosupression
Ulcerative conditions

Question 10

Describe the different subtypes of necrotising fascitis?

Answer 10

Type 1 - polymicrobial infection usually with Ana anaerobe and a facultative anaerobe
Type 2 - mono microbial infection, commonly group a strep
Type 3 - mono microbial infection, usually a gram negative bacteria
Type 4 - moonomicrobial infection with fungus usually in immunocompromised patients

Question 11

Describe the appearance of necrotising fascitis?

Answer 11

Severe, disproportionate pain -> anaesthesia over infection site
Oedema and erythema
Associated skin changes - Crepitus, vesicles, bullae, grey discolouration
Systemic signs of infection

Question 12

What is the most common causative organism of erysipelas?

Answer 12

Strep pyogenes

Question 13

What antibiotics are typically used in the treatment of erysipelas?

Answer 13

Penicillins
Clindamycin
Erythromycin

Question 14

What is the definition of impetigo?

Answer 14

A common superficial, highly contagious, blistering bacterial infection of the skin

Question 15

What areas of the skin are typically affected by bullous impetigo?

Answer 15

Skin folds - axillae, groin etc.

Question 16

What groups of patients typically develop bullous impetigo?

Answer 16

Newborn babies

Immunocompromised adults

Question 17

What are the most common causative organisms of impetigo?

Answer 17

Group A strep
Staph aureus (s.aureus is the cause of bullous impetigo)

Question 18

What more serious condition can bullous impetigo evolve into?

Answer 18

Staphylococcal scalded skin syndrome

Question 19

What is the management of impetigo?

Answer 19

Usually no treatment as it will usually self-resolve
In some cases topical antibiotics are used and if severe or refractory oral antibiotics are used
Good skin hygiene is important

Question 20

What is staphylococcal scalded skin syndrome?

Answer 20

A blistering skin infection caused by s.aureus

Question 21

What is pathophysiology of staphylococcal scalded skin syndrome?

Answer 21

epidermylotic exotoxin A and B are released by staph aureus and cause detachment within the epidermal layer due to the breakdown of desmosomes

Question 22

Describe the presentation of staphylococcal scalded skin syndrome?

Answer 22

Fever, irritability and widespread erythema
Within 12-48 hours widespread fluid-filled blisters forms on face, buttocks and intertriginous areas (but NOT mucosa) and these are easily breakable
Nikolsky’s sign is positive

Question 23

What is the most common infectious cause of folliculitis?

Answer 23

S.aureus

Question 24

Describe the appearance of folliculitis?

Answer 24

Multiple erythematous folliculocentric papules and pustules.
Often puritic.
Painful furnaces develop if the infection spreads more deeply.
Often resolves with hyperpigmentation in darker skin types

Question 25

Describe the management of folliculitis.

Answer 25

Usually no treatment required as it is usually a self-limiting conditions
Topical benzoyl peroxide alongside good skin hygiene may be used
In severe cases, oral antibiotics are used.
Incision and drainage is required if an abscess develops.