Cellulitis: Aetiology
Cellulitis is an acute, spreading bacterial infection of the dermis and subcutaneous tissue, usually complicating a wound, ulcer, or dermatitis.
Affected skin becomes tender, warm, erythaematous and swollen. Any age group may be affected and numerous organisms can cause it.
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Erysipelas
Erysipelas is an acute superficial cellulitis with invasion of the lymphatics. It is generally caused by Streptococci, especially Streptococcus pyogenes. Lesions are classically well-demarcated, fiery red and raised. A ‘peau d’orange’ appearance (dimpling) is due to tethering of hair follicles within the oedematous dermis. Infants and the elderly are more commonly affected.
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Common causes of cellulitis
The common causes of cellulitis are shown in Table 1.
| Common causes | Type of infection |
|---|---|
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Atypical causes of cellulitis
The atypical causes of cellulitis are shown in Table 2.
| Atypical organisms | Common source of organisms |
|---|---|
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Learning bite
Atypical organisms can cause severe, rapidly progressive cellulitis with marked systemic features.