What is cellulitis?
Cellulitis is caused by a bacterial infection of the dermis layer of the skin and the deeper subcutaneous tissues.
Often the infection is due to a break or puncture to the skin which allows bacteria to enter, however in some cases no obvious break to skin integrity can be located.
What are the most common site of infection for cellulitis?
- Legs ( typical presentation is of unilateral leg symptoms following a break in the skin)
- Face
- although can occur in any area of the skin
What is the epidemiology of Cellulitis?
Very common infection presenting to primary, secondary and emergency care
Incidence of 24.6/1000
What are the risk factors for Cellulitis?
- Wounds to the skin
2.Diabetes - Old age
- Insect bites
- Obesity
- Fungal infections between toes
- Skin conditions such as eczema
- Chronically swollen legs (e.g. lymphoedema)
- Chronic venous insufficiency
- Varicose veins
- Intravenous drug user
- Immunosuppression
- Previous cellulitis
What are the most common causative organisms for cellulitis?
Group A beta-haemolytic streptococci – Streptococcus pyogenes
Staphylococcus aureus
What are the lesser common causative organisms for cellulitis?
- Streptococcus pneumonia
- Haemophilus influenza – Often in infants prior to Hib vaccination
- Gram negative bacilli
- Anaerobes
What are the clinical presentations of cellulitis?
- Erythema - blends into surrounding skin
- Tracking can occur along blood vessels and tends to spread more quickly than generalised erythema
- Pain
- Swelling
- Warmth of affected skin
- Often a site of skin damage - Ulcer, wound, bite mark, injection site
What are systemic symptoms of cellulitis?
- Fever
- Malaise
- Nausea
- rigors
- Confusion in the elderly
What are five differential for cellulitis?
- DVT
- Varicose eczema
- Ruptured Baker’s cyst
- Necrotising fasciitis
- Metastatic cancer (Carcinoma erysipelatoid’s)
What investigations are used in primary care?
They aren’t usually required as a diagnosis can be made of clinical history and examination alone.
If there is an obvious wound in the skin this can be swabbed
What investigations are used in secondary care?
- Bloods - Raised WCC, CRP, fasting glucose, lipids and cholesterol
- Blood cultures - Identify the causative organism and direct antibiotic choice
- X-ray, CT, MRI - If concerns for deeper infection and/or foreign body in situ
What is the general management for cellulitis?
- Analgesia
- Elevated legs
- Requirement for Tetanus vaccination
When should a patient be sent to the hospital with cellulitis?
- Significantly unwell with symptoms such as tachycardia, tachypnoea, hypotension, vomiting, or acute confusion
- Unstable co-morbidities such as uncontrolled diabetes
- Contaminated wound
- Limb threatening infection due to vascular compromise
- Sepsis or life threatening complications such as necrotizing fasciitis
- Very young (<1 years) or frail
- Immunocompromised
- Gross limb swelling
- Facial cellulitis
- Periorbital cellulitis
What is the first-line treatment for mild/minor cellulitis in primary care?
PO Flucloxacillin 500mg QDS for 7 days
Or if penicillin allergic
PO Erythromycin 500 QDS or Clarithromycin 500 mg BD for 7 days
What is first-line treatment for cellulitis in hospital?
Flucloxacillin 1 gram QDS IV (For 48 hours, then r/v if can be stepped down to oral)
Or if penicillin allergic
Clindamycin 600mg QDS IV (For 48 hours, then r/v if can be stepped down to oral)
If case may have been contaminated by fresh or salt water consult microbiology
What are the 4 acute complications associated with cellulitis?
- Abscess formation
- Sepsis
- Myositis/osteomyelitis
- Necrotizing fasciitis - consider if pain not being eased by analegsia
What are 2 chronic complications associated with cellulitis?
- Persistent leg ulceration
- Chronic lymphoedema
What is the usual prognosis for cellulitis?
Vast majority of patients will make a complete and uncomplicated recovery
Recurrence rates of cellulitis have been reported between 11-16%
What is erysipelas?
Superficial infection that extends into the lymphatics with erythematous lesions, indurated with sharply-demarcated margins, and have erythematous, ascending streaks
What are the top 3 bacterial causes of cellulitis?
1) Staphylococcus aureus
2) Group A Strep (Strep pyogenes)
3) Group C Strep (Strep dysgalacitiae)
In what patients should MRSA be considered as a cause of cellulitis?
patient with recent hospital admissions or on antibiotics
Give 7 clinical presentations associated with cellulitis:
1) erythema
2) warm/hot to the touch
3) tense skin
4) thickened skin
5) oedematous
6) bullae
7) a golden-yellow crust
What would a golden-yellow crust in cellulitis indicate?
Staphylococcus aureus
Give 3 systemic features associated with cellulitis:
1) fevers
2) malaise
3) rigors
