Skin and soft tissue infections

Question 1

What is cellulitis?

Answer 1

Cellulitis is an acute spreading infection of the skin with visually indistinct borders that principally involves the dermis and subcutaneous tissue.

Question 2

What organisms commonly cause cellulitis?

Answer 2

B haemolytic strep (group A) and staph aureus

Question 3

What are Sx of cellulitis?

Answer 3

• Erythema
  
  • Dull pain or tenderness
  • Warmth
  • Blistering
  • Erosions and ulceration
  • Swelling/oedema

May be systemic symptoms if severe

Question 4

What are risk factors for cellulitis?

Answer 4

• Previous episode(s) of cellulitis
  
  • Venous disease (e.g. gravitational eczema, leg ulceration and/or lymphoedema)
  • Current or prior injury (e.g. trauma/surgical wounds)
  • Immunodeficiency
  • Diabetes
  • Chronic kidney disease
  • Chronic liver disease
  • Obesity
  • Pregnancy

Question 5

What Ix in cellulitis?

Answer 5

None normally needed.

Can do routine bloods (WCC/CRP), cultures, and skin swabs if systemically unwell

Question 6

What is Rx of cellulitis?

Answer 6

• Analgesia e.g. paracetamol, ibuprofen
• Ensure adequate oral intake or IV fluids if required
• Marking the edge of erythema to monitor spread/regression
Antibiotics e.g. flucloxacillin (or doxy) 7 days oral, IV if unwell

Question 7

What is erysipelas?

Answer 7

Erysipelas is a distinct form of superficial cellulitis with notable lymphatic involvement. It is raised and sharply demarcated from uninvolved skin.

usually affects face

Question 8

What is impetigo?

Answer 8

Impetigo is a superficial bacterial skin infection which is highly contagious and common in children

Question 9

What are Sx of impetigo?

Answer 9

• Golden encrusted skin lesions with inflammation localised to the dermis, giving erythematous base.
• Often well-defined localised lesions
Occur on nose and face

Question 10

What are causes of impetigo?

Answer 10

Staph aureus and group A strep

Question 11

What is Rx of cellulitis?

Answer 11

• Topical 
		○ Fusidic acid 
		○ Given in localised infections 
	• Oral antibiotics
		○ Flucloxacillin 
		○ Given for 7 days if severe.

Question 12

What is tinea?

Answer 12

A superficial fungal skin infection which invades and grows in dead keratin of the skin and nails.

Question 13

What Ix for tinea?

Answer 13

Clinical diagnosis, but can do skin scrapings and scalp brushing

Question 14

What Rx for tinea?

Answer 14

Topical anti-fungal e.g. terbanifine, ketonacazle shampoo, systemic terbanifine in more severe infections

Question 15

What is a soft tissue abscess?

Answer 15

Infection within the dermis or fat layers with the development of walled off infection and pooled pus.

Question 16

How is soft tissue abscess treated?

Answer 16

• Lysing and surgical drainage
○ There is limited antibiotics penetration into the abscess
○ Antibiotics shouldn’t be required if abscess is fully drained and there is no surrounding cellulitis.
• PVL toxin; virulence factor for causing boils and abscesses, necrotising infections. May change antibiotics choice. Clindamycin stop production of toxin

Question 17

What is necrotising fasciitis?

Answer 17

A rapidly progressive infection of the deep fascia causing necrosis of the subcutaneous tissue.

Question 18

What are the 2 types of NF?

Answer 18

type 1 = polymicrobial. Older people, existing wounds, scrotal

type 2 = monomicrobial, usually strep pyogenes, in younger people with healthy tissue after a cut

Question 19

What are risk factors for NF?

Answer 19

• Recent wound or bite, or surgery
  
  • Diabetes
  • Immuno-compromised individuals
  • Alcohol XS
  • IVDU
  • Chronic kidney disease
  • NSAIDS

Question 20

What Ix for NF?

Answer 20

Treat immediately/call surgeons if suspected.

Can do bloods, blood cultures, gram stain of exudate

MRI scan can show extent of NF, but can delay treatment

Question 21

What Rx for NF?

Answer 21

Surgical debridement

Antibiotics: benzypenicillin + flucloxacillin + gentamicin + clindamycin + metrondiazole

IVIG if type 2 NF caused by group A strep may help

Question 22

What are Sx of NF?

Answer 22

Pain out or proportion to symptoms

Erythema, painless ulcers, black necrotic skin, crepitus if over a joint

Systemic Sx e.g. fever, hypotension, tachycardia