Cellulitis is a common bacterial infection of the skin, which can affect all ages. It usually affects a limb but can occur anywhere on the body. Symptoms and signs are usually localised to the affected area but patients can become generally unwell with fevers, chills and shakes.
Predisposing factors
- Problems with venous or lymphatic drainage of the area
- Previous injury to the limb (e.g. trauma, surgical wounds, radiotherapy, surgery)
- Diabetes
- Alcoholism
- Obesity
- Swelling of the legs
- Pregnancy
- Tinea pedis (or athlete's foot) in the toes of the affected limb
Clinical features
Some or all of the following features may be seen over the affected skin.
- Redness
- Swelling
- Increased warmth
- Tenderness
- Blistering
- Abscess
If there is no increased warmth over the skin it is unlikely to be cellulitis.
Lymphangitis is a red line originating from the cellulitis and leading to tender swollen lymph glands draining the affected area (e.g. in the groin with a leg cellulitis). It is caused by infection within the lymph vessels.
After successful treatment, the skin may flake or peel off as it heals.
Causes
Cellulitis is caused by a bacterial infection of the skin. The most common infecting organisms are Streptococcus pyogenes (two thirds of cases) and Staphylococcus aureus (one third). Rare causes include Pseudomonas aeruginosa, particularly following a puncture wound involving the foot or hand, and Haemophilus influenzae in children with facial cellulitis.
Diagnosis
The diagnosis of cellulitis is based on the clinical features. Investigations are rarely needed or useful. Blood cultures may be of use if a patient is very unwell. Occasionally further investigations are required to rule out other possible diagnoses such as deep vein thrombosis of the leg, radiation damage following radiotherapy, or inflammatory breast cancer.
Treatment
Most patients can be treated with oral antibiotics at home, usually for 5 to 10 days. However if there are signs of systemic illness or extensive cellulitis, treatment may require intravenous antibiotics. Treatment for uncomplicated cellulitis is usually for 10 to 14 days but antibiotics should be continued until all signs of infection have cleared (redness, pain and swelling) - sometimes for several months.
Oral antibiotics used commonly are penicillin, flucloxacillin, cefuroxime or erythromycin. The usual intravenous antibiotics used are penicillin-based antibiotics (e.g. penicillin G or flucloxacillin) or cephalosporins (e.g. cefotaxime or cefazolin) for a few days. Sometimes oral probenecid is added to maintain antibiotic levels in the blood. In situations where a broader antibiotic cover is required, for example a diabetic patient with a foot ulcer complicated by cellulitis, amoxicillin and clavulanic acid may be used. Clindamycin and vancomycin are alternative antibiotics in patients with serious penicillin or cephalosporin allergy.
Patients with recurrent cellulitis should
- Avoid trauma, wear long sleeves and pants in high risk activities e.g. gardening
- Keep skin clean and well moisturised, with nails well tended
- Avoid having blood tests taken from the affected limb
- Treat fungal infections of hands and feet early
- Keep swollen limbs elevated during rest periods to aid lymphatic circulation
Some patients with very frequent cellulitis may benefit from chronic suppressive antibiotic treatment.
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Author: Dr Amy Stanway MB ChB,
Department of Dermatology, Health Waikato, Private Bag 3200, Hamilton, New Zealand.
Created 2001. Last updated 25 Dec 2007. © 2007 NZDS. Disclaimer.
