Skin and Soft Tissue Infections

Cellulitis is an infection of the skin and the soft tissues underneath. The skin normally acts as a very effective physical barrier between the environment and soft tissues. When a patient presents with cellulitis look for a breach in the skin barrier and a point of entry for the bacteria. This may be due to skin trauma, eczematous skin, fungal nail infections or ulcers.


The skin will demonstrate changes:

  • Erythema (red discolouration)
  • Warm or hot to touch
  • Tense
  • Thickened
  • Oedematous
  • Bullae (fluid-filled blisters)
  • A golden-yellow crust can be present and indicate a staphylococcus aureus infection


The most common causes are:

  • Staphylococcus aureus
  • Group A Streptococcus (mainly streptococcus pyogenes)
  • Group C Streptococcus (mainly Streptococcus dysgalactiae)

 Other causes

  • MRSA

Eron Classification

This is the classification system NICE recommends for the assessment of the severity of cellulitis:

  • Class 1 – no systemic toxicity or comorbidity
  • Class 2 – systemic toxicity or comorbidity
  • Class 3 – significant systemic toxicity or significant comorbidity
  • Class 4 – sepsis or life-threatening

Admit the patient for intravenous antibiotics if they are class 3 or 4. Also consider admission for frail, very young or immunocompromised patients.



Flucloxacillin is very effective against staph infections and also works well against other gram positive cocci. It is usually the first choice in treating cellulitis and can be given oral or intravenous.


  • Clarithromycin
  • Clindamycin
  • Co-amoxiclav


Last updated March 2019