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Cellulitis
Cellulitis

Cellulitis

Cellulitis is an acute, non-necrotising inflammation of the deep dermis and subcutaneous tissue layers. It usually affects the lower limbs.

Erysipelas is a similar infection but is more superficial, as it involves the upper dermis and superficial lymphatics. It can be considered a subset of cellulitis.

🦠 Causative agents

There are 2 main causative agents:

  1. Strep. pyogenes
  2. S. aureus

Both of these organisms enter the dermis and subcutaneous tissue through skin breakage.

Other causative agents include: h. influenzae, strep. pneumoniae.

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😷 Presentation

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There may be well-demarcated or diffuse:

  1. Erythema
  2. Swelling
  3. Tenderness
  4. Warmth

A wound/skin trauma may also be noticeable.

Systemic symptoms include:

  • Fever/chills
  • Malaise

🔍 Investigations

Cellulitis is diagnosed off of a clinical diagnosis. Further investigations are not required. Swabs for cultures and blood tests may be done if there is a concern for septicaemia.

🔢 Classification

NICE uses the Eron classification to guide the management of patients with cellulitis:

I
No signs of systemic toxicity and the individual has no uncontrolled co-morbidities.
II
Systemically unwell patient OR Systemically well + co-morbidity that may complicate or delay resolution of the infection (e.g. PAD, chronic venous insufficiency, morbid obesity)
III
Significant systemic upset (acute confusion, tachycardia, tachypnoea, hypotension) OR Unstable co-morbidities that may interfere with response to treatment OR Limb-threatening infection due to vascular compromise
IV
Sepsis OR Severe, life-threatening infection such as NF.

🧰 Management

💊
Management of cellulitis in children ≥1 month:

The management of cellulitis of course depends on the class/severity of the disease.

  1. Class I
  • 🥇 Flucloxacillin is first-line.
  • 🥇 Clarithromycin - if the child has a true penicillin allergy.
  • 🥈 Co-amoxiclav - if flucloxacillin is unsuitable.
  • Erythryomycin to be used during pregnancy.

If there is an infection near the eyes or nose → seek specialist advice and prescribe:

  • 🥇 Co-amoxiclav or clarithromycin
  • Clarithromycin + metronidazole - if anaerobes are suspected.
  1. Class II
  • Short-term hospitalisation (up to 48 hours)
  • Outpatient parenteral antibiotic therapy (OPAT).
  1. Class III/IV
  • Urgent hospital admission
  • IV antibiotics (4 C’s)
    • Co-amoxiclav
    • Cefuroxime
    • Clindamycin
    • Ceftriaxone

      • The same protocol applies for the patients mentioned in the criteria section.

      The reason we give IV antibiotics is to prevent cavernous sinus thrombosis (Class V Chandler’s classification).

Other things that need to be done are:

  1. Risk factor management such as wound treatment.
  2. Management of comorbidities - such as uncontrolled diabetes/hypertension.
  3. Lifestyle advice such as weight loss and use of emollients to prevent dry skin and cracking.
🏥
Urgent hospital admission:

Criteria for admission and IV antibiotics includes the following:

  • Eron class III or IV
  • Severe rapidly deteriorating cellulitis
  • <1 year old or frail
  • Immunocompromised
  • Significant lymphoedema
  • Facial cellulitis or periorbital cellulitis

🚨 Complications

  • Sepsis
  • Necrotising fasciitis
  • Persistent limb ulceration
  • Recurrent cellulitis