Erysipelas and cellulitis

Last updated: October 2020

Acute skin infections, due to bacteria (usually Group A beta-haemolytic streptococcus and sometimes Staphylococcus aureus, including methicillin resistant S. aureus–MRSA) that enter through a break in the skin.

The main risk factors are: venous insufficiency, obesity, oedema or lymphoedema, history of erysipelas or cellulitis, immunosuppression and cutaneous inflammation (e.g. dermatosis, wound).

Erysipelas is a superficial infection (affecting the dermis and superficial lymph vessels), while cellulitis affects the deeper tissues (deep dermis layers and subcutaneous fat).

Generally, these infections affect the lower extremities and sometimes the face. If the orbital and periorbital tissues are infected, see Periorbital and orbital cellulitis, Chapter 5. If the infection is perifollicular, see Furuncles and carbuncles, Chapter 4.

Clinical signs

• Warm, tender, swollen well–demarcated erythematous plaque.
• Fever, lymphadenopathy and lymphangitis.
• Look for a portal of entry (bite, ulcer, wound, intertrigo, eczema, fungal infection, etc.).
• In case of intense pain disproportionate to the skin lesion, hypoesthesia, rapidly progressing local signs, crepitation, skin necrosis or critically ill appearing patient, consider necrotising fasciitis that is a surgical emergency (see Necrotising infections of the skin and soft tissues, Chapter 10).
• Other complications: septicaemia (see Septic shock, Chapter 1), acute glomerulonephritis, osteomyelitis, septic arthritis.
• The main differential diagnoses include: contact dermatitis, stasis dermatitis due to venous insufficiency, venous thrombosis and erythema migrans characteristic of Lyme disease.

Paraclinical investigations

• Ultrasound: can detect signs of cellulitis and rule out an underlying abscess, deep vein thrombosis or a foreign body.
• Radiography: can detect a foreign body, underlying osteomyelitis (or gas in the subcutaneous tissue in case of a necrotising infection, nevertheless the absence of gas does not rule out this diagnosis).
• Test for proteinuria with urine dipstick 3 weeks after infection to look for glomerulonephritis.

Treatment

• In all cases:
  • Outline the area of erythema with a pen in order to follow the infection a Citation a. The erythema will regress if the treatment is effective. If the erythema spreads consider a treatment failure (MRSA or a necrotising infection). .
  • Bed rest, elevation of affected area (e.g. leg). 
  • Treatment of pain (Chapter 1). Avoid NSAIDs that may increase the risk of necrotising fasciitis.
  • Administer antibiotics: either orally or IV depending on severity.
  • Treat portal of entry and comorbidities.
  • Check and/or catch up tetanus vaccination (see Tetanus, Chapter 7).
  • In case of necrotising fasciitis, septic arthritis or osteomyelitis: urgent transfer to a surgical centre, initiate IV antibiotic treatment while awaiting transfer.

• Hospitalize for the following: children younger than 3 months, critically ill appearing patient b Citation b. Critically ill appearing child: weak grunting or crying, drowsy and difficult to arouse, does not smile, disconjugate or anxious gaze, pallor or cyanosis, general hypotonia. , local complications, debilitated patient (chronic conditions, the elderly) or if there is a risk of non-compliance with or failure of outpatient treatment. Treat other patients as outpatients.

• Outpatient antibiotherapy c Citation c. For penicillin-allergic patients, clindamycin PO for 7 to 10 days (children: 10 mg/kg 3 times daily; adults: 600 mg 3 times daily).  : 
  cefalexin PO for 7 to 10 days
  Children 1 month to under 12 years: 25 mg/kg 2 times daily
  Children 12 years and over and adults: 1 g 2 times daily
  or
  amoxicillin/clavulanic acid (co-amoxiclav) PO for 7 to 10 days. 
  Use formulations in a ratio of 8:1 or 7:1. The dose is expressed in amoxicillin:
  Children < 40 kg: 25 mg/kg 2 times daily
  Children ≥ 40 kg and adults:
  Ratio 8:1: 2000 mg daily (2 tablets of 500/62.5 mg 2 times daily)
  Ratio 7:1: 1750 mg daily (1 tablet of 875/125 mg 2 times daily)

In the event of worsening clinical signs after 48 hours of antibiotic treatment, consider IV route.

• Inpatient antibiotherapy d Citation d. For penicillin-allergic patients, clindamycin IV infusion (children: 10 mg/kg 3 times daily; adults: 600 mg 3 times daily). :
  • First line therapy: 
    cloxacillin IV infusion over 60 minutes e Citation e. Cloxacillin powder for injection should be reconstituted in 4 ml of water for injection. Then dilute each dose of cloxacillin in 5 ml/kg of 0.9% sodium chloride or 5% glucose in children less than 20 kg and in a bag of 100 ml of 0.9% sodium chloride or 5% glucose in children 20 kg and over and in adults.
    Children 1 month to under 12 years: 12.5 to 25 mg/kg every 6 hours
    Children 12 years and over and adults: 1 g every 6 hours 
    or
    amoxicillin/clavulanic acid (co-amoxiclav) by slow IV injection (3 minutes) or IV infusion (30 minutes). The dose is expressed in amoxicillin:
    Children under 3 months: 30 mg/kg every 12 hours 
    Children 3 months and over: 20 to 30 mg/kg every 8 hours (max. 3 g daily)
    Adults: 1 g every 8 hours

If there is clinical improvement after 48 hours (afebrile and erythema and oedema have improved) switch to cefalexin or amoxicillin/clavulanic acid PO at the doses indicated above to complete 7 to 10 days of treatment.

• If there is no clinical improvement after 48 hours, consider MRSA: 
  clindamycin IV infusion over 30 minutes f Citation f. Dilute each dose of clindamycin in 5 ml/kg of 0.9% sodium chloride or 5% glucose in children less than 20 kg and in a bag of 100 ml of 0.9% sodium chloride or 5% glucose in children 20 kg and over and in adults.
  Children 1 month and over: 10 mg/kg every 8 hours
  Adults: 600 mg every 8 hours

After 48 hours, change to clindamycin PO at the doses indicated above to complete 7 to 10 days of treatment.