Cellulitis

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Cellulitis is an infection of skin, specifically the dermis and subcutaneous tissues usually following a break in the skin such as infected wound or prick by a pin, nail, thorn, insect bite or cracks between the toes from athlete’s foot. 

It may affect any part of the body, but it affects the legs mostly. Obesity and leg swelling are risk factors. It is important to rule out acute osteomyelitis, necrotizing fasciitis and Deep Vein Thrombosis (DVT).

Cause

  • Streptococcus pyogenes (the commonest cause)
  • Staphylococcus aureus

Symptoms

  • Pain over area affected
  • Swelling of the affected parts
  • Reddening or darkening of the overlying skin
  • Blistering 
  • Ulcers 
  • Fever 
  • Rigors
  • Malaise
  • Vomiting
  • Confusion

Signs

  • Swelling of affected part
  • Blisters
  • Localised tenderness and skin colour change
  • Localised warmth
  • Ulcers including the web spaces  
  • Enlarged and tender regional lymph nodes 
  • Underlying pus
  • Offensive wound
  • Fever

Investigations

  • FBC, ESR 
  • CRP
  • Blood culture
  • Fasting blood glucose
  • Gram stain and culture of discharge
  • X-ray of affected part

TreatmentTreatment Objectives

  • To relieve pain  
  • To control and eradicate the infection
  • To treat predisposing conditions
  • To prevent complications like ulceration and osteomyelitis 

Non-pharmacological treatment

  • Rest and elevate the affected part if possible
  • Clean and dress any open wounds
  • Incision and drainage if pus forms
  • Debridement 
  • Split skin graft (if indicated)  

Pharmacological treatment 

See sections below

Referral Criteria

Refer all cases with treatment failure, complications or ulceration requiring debridement and grafting to a plastic or general surgeon

1st Line Treatment

Evidence Rating: [C]

  • Amoxicillin, oral,

Adults

500 mg-1 g 8 hourly for 7 days

Children

6-12 years; 250 mg 8 hourly for 7 days

1-5 years; 125 mg 8 hourly for 7 days

< 1 year; 62.5 mg 8 hourly for 7 days

And

  • Flucloxacillin, oral,

Adults

500 mg 6 hourly for 7 days 

Children

> 10 years;  250-500 mg 6 hourly for 7 days   

2-10 years; 125-250 mg 6 hourly for 7 days

< 2 years;  62.5-125 mg 6 hourly for 7 days 

2nd Line Treatment

Evidence Rating: [C]

  • Co-amoxyclav, oral,

Adults 

625 mg 8-12 hourly for 5-7 days 

Children

11-18 years; 625 mg 8-12 hourly for 5-7 days

6-10 years; 457 mg 8-12 hourly for 5-7 days

1-5 years; 228 mg 8-12 hourly for 5-7 days

< 1 year; 114 mg 8-12 hourly for 5-7 days

For Individuals with penicillin allergy

Evidence Rating: [C]

  • Erythromycin, oral,

Adults 

250-500 mg 6 hourly for 7 days

Children 

8-18 years; 250-500 mg 6 hourly for 7 days

2-7 years; 250 mg 6 hourly for 7 days

< 2 years; 125 mg 6 hourly for 7 days

Or

  • Clindamycin, oral,

Adults

150-300 mg 6-8 hourly for 7 days

Children

12-18 years;150-300 mg 6 hourly for 7 days

1 month-11 years; 3-6 mg/kg 6 hourly for 7 days

1st Line Treatment 
  • Amoxicillin + Clavulanic Acid, IV

Adults

1.2 g 12 hourly, increased to 1.2 g 8 hourly in severe infections

Children

12-18 years; 600 mg to 1.2 g 12 hourly, increased to 1.2 g 8 hourly in severe infections

3 months-12 years; 30 mg/kg 12 hourly, increased to 30 mg/kg 8 hourly in severe infections

7 days-3 months; 30 mg/kg 8 hourly

Preterm and < 7 days; 30 mg/kg 12 hourly 

Then 

  • Amoxicillin + Clavulanic Acid, oral

Adults

1 g 12 hourly 

Children

> 12 years; 500/125 mg 12 hourly 

4-12 years; 5 ml of 400/57 mg suspension 12 hourly 

1-4 years; 5 ml of 200/28 mg suspension 12 hourly 

3 months-1 year; 20 mg/kg (of amoxicillin) 12 hourly 

< 3 months; 15 mg/kg (of amoxicillin) 12 hourly 

And

Evidence Rating: [B]

  • Cloxacillin, IV

Adults

500 mg 6 hourly 

Children 

5-12 years; 250 mg 6 hourly 

1-5 years; 125 mg 6 hourly 

< 1 year; 62.5 mg 6 hourly 

Then

  • Flucloxacillin, oral

Adults

500 mg 6 hourly 

Children 

5-12 years; 250 mg 6 hourly 

1-5 years; 125 mg 6 hourly 

< 1 year; 62.5 mg 6 hourly 

2nd Line Treatment 

  • Amoxicillin + Clavulanic Acid, IV

Adults

1.2 g 12 hourly, increased to 1.2 g 8 hourly in severe infections

Children

12-18 years; 600 mg to 1.2 g 12 hourly, increased to 1.2 g 8 hourly in severe infections

3 months-12 years; 30 mg/kg 12 hourly, increased to 30 mg/kg 8 hourly in severe infections

7 days-3 months; 30 mg/kg 8 hourly 

Preterm and < 7 days; 30 mg/kg 12 hourly 

Then 

  • Amoxicillin + Clavulanic Acid, oral

Adults

1 g 12 hourly 

Children

> 12 years; 500/125 mg 12 hourly 

4-12 years; 5 ml of 400/57 mg suspension 12 hourly 

1-4 years; 5 ml of 200/28 mg suspension 12 hourly 

3 months-1 year; 20 mg/kg (of amoxicillin) 12 hourly 

< 3 months; 15 mg/kg (of amoxicillin) 12 hourly 

And

  • Clindamycin, IV

Adults

300 mg 6 hourly or 600 mg 8 hourly 

Children

3-6 mg/kg 6 hourly 

Then 

  • Clindamycin, oral

Adults

150-300 mg 6-8 hourly 

Children

12-18 years; 150-300 mg 6 hourly 

1 month-11 years; 3-6 mg/kg 6 hourly 

For methicillin resistant Staph. aureus  

Evidence Rating: [B]

  • Vancomycin, IV

Adults

1 g 12 hourly by slow infusion over 1 hour (max. 2 g daily)

Children

1 month-12 years; 10 mg/kg per day in divided doses 6-12 hourly (max. 1 g daily)